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Motion Tracking Interface for use with Moving-Head

Spotlights (Stage Stalker)

Project Design Report

Design Team 04

Ben Cochran (Project Leader)

Kevin Gerhart (Archivist)

Eric Hillen (Hardware Manager)

Chris Trowbridge (Software Manager)

Faculty Advisor: Dr. Nghi Tran

Senior Design Coordinator: Gregory A. Lewis

November 15, 2012

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Table of Contents Abstract ................................................................................................................... v

1. Problem Statement .................................................................................................. 1

Need ........................................................................................................................ 1

Objective ................................................................................................................. 2

Background ............................................................................................................. 3

Position-Locating Methods ................................................................................ 3

Using Ultrasound with Time of Arrival ............................................................. 7

Wireless Data Transmission ............................................................................... 9

Moving-Head Lights ........................................................................................ 11

DMX512 Lighting Control Protocol ................................................................ 12

Objective Tree ....................................................................................................... 14

2. Design Requirements Specification ...................................................................... 15

3. Accepted Technical Design .................................................................................. 16

Theory of Operation .............................................................................................. 16

Block Diagrams .................................................................................................... 21

Hardware Block Diagrams ............................................................................... 21

Software Block Diagrams ................................................................................ 39

4. Parts List ............................................................................................................... 52

5. Project Schedules .................................................................................................. 55

6. Design Team Information ..................................................................................... 58

7. Conclusions and Recommendations ..................................................................... 58

8. References ............................................................................................................. 59

9. Appendices ............................................................................................................ 60

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List of Figures Figure 1: Q-Spot™ 560-LED by Chauvet [1]. ................................................................... 1 Figure 2: Data Acquisition and Processing Diagram. ......................................................... 2 Figure 3: Stage Stalker Setup Concept Drawing. ............................................................... 3 Figure 4: Time of Arrival Method [2]. ................................................................................ 4 Figure 5: Time Difference of Arrival Method [2]. ............................................................. 5 Figure 6: Cell of Origin Method [2]. .................................................................................. 6 Figure 7: Angle of Arrival Method [2]. .............................................................................. 6 Figure 8: Ultrasonic Ceramic Transducer [4]. .................................................................... 7 Figure 9: Ultrasonic Transmission [5]. ............................................................................... 8 Figure 10: Ultrasonic Receiving [5]. .................................................................................. 8 Figure 11: ZigBee Sample Topology ................................................................................ 11 Figure 12: 3 and 5-pin DMX connectors [3]. ................................................................... 12 Figure 13: DMX512 Packet Timing. ................................................................................ 13 Figure 14: Diagram of a DMX512 Packet [3]. ................................................................. 13 Figure 15: Objective Tree ................................................................................................. 14 Figure 16: Hardware Level 0 Block Diagram, Motion Tracking Spotlight Interface. ..... 21 Figure 17: Hardware Level 1 Block Diagram, Motion Tracking Spotlight Interface. ..... 22 Figure 18: Hardware Level 2 Block Diagram, Wireless Transmitter. .............................. 23 Figure 19: Hardware Level 2 Block Diagram, Sensors. ................................................... 24 Figure 20: Sensor Power Regulator, PIC and ZigBee Schematic. .................................... 25 Figure 21: Hardware Level 2 Block Diagram, PACU. ..................................................... 26 Figure 22: PACU FPGA Schematic. ................................................................................ 27 Figure 23: PACU DMX Driver. ........................................................................................ 27 Figure 24: PACU ZigBee Module. ................................................................................... 27 Figure 25: Hardware Level 3 Block Diagram, Transmitter Intelligence. ......................... 28 Figure 26: Transmitter PIC and ZigBee Schematic. ......................................................... 29 Figure 27: Transmitter Timing Schematic. ....................................................................... 29 Figure 28: Hardware Level 3 Block Diagram, Ultrasonic Signal Generator. ................... 30 Figure 29: Transmitter Amplification Schematic. ............................................................ 31 Figure 30: Hardware Level 3 Block Diagram, Transmitter Power Regulator. ................. 32 Figure 31: Transmitter Power Regulator Schematic. ........................................................ 33 Figure 32: Hardware Level 3 Block Diagram, PACU Power Unit. .................................. 34 Figure 33: PACU Power Unit Schematic. ........................................................................ 35 Figure 34: Sallen-Key Band-Pass Filter Topology. .......................................................... 35 Figure 35: Hardware Level 3 Block Diagram, Receiving Chain. ..................................... 37 Figure 36: Sensor Amplifier Chain Schematic. ................................................................ 38 Figure 37: Software Level 0 Block Diagram. ................................................................... 39 Figure 38: Software Level 1 Block Diagram, Motion Tracking Spotlight Interface. ....... 40 Figure 39: Software Level 2 Block Diagram, Wireless Transmitter. ............................... 41 Figure 40: Software Level 2 Block Diagram, Sensors. .................................................... 42

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Figure 41: Software Level 2 Block Diagram, PACU. ...................................................... 43 Figure 42: Software Level 3 Block Diagram, Timing Information Generator. ................ 44 Figure 43: Software Level 3 Block Diagram, Position Calculator. .................................. 45 Figure 44: Software Level 3 Block Diagram, Timestamp Relay. ..................................... 46 Figure 45: Software Level 4 Block Diagram, Timestamp Generator. .............................. 47 Figure 46: Software Level 4 Block Diagram, ToA Calculator. ........................................ 48 Figure 47: ToA Signals for Calculation. ........................................................................... 49 Figure 48: Software Level 4 Block Diagram, Position Calculator. .................................. 50 Figure 49: Software Level 4 Block Diagram, DMX Formatter. ....................................... 51

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List of Tables Table 1: Wireless Protocol Comparison [9]. ....................................................................... 9 Table 2: Moving Yoke Light Comparisons. ..................................................................... 11 Table 3: 5-pin DMX pin assignment. ............................................................................... 12 Table 4: Functional breakdown of a DMX512 packet [3]. ............................................... 13 Table 5: Design Requirements. ......................................................................................... 15 Table 6: Hardware Level 0 Block Diagram, Motion Tracking Spotlight Interface. ......... 21 Table 7: Hardware Level 1 Block Diagram, Motion Tracking Spotlight Interface. ......... 22 Table 8: Hardware Level 2 Block Diagram, Wireless Transmitter. ................................. 23 Table 9: Hardware Level 2 Block Diagram, Sensors. ...................................................... 24 Table 10: Hardware Level 2 Block Diagram, PACU. ...................................................... 26 Table 11: Hardware Level 3 Block Diagram, Transmitter Intelligence. .......................... 29 Table 12: Hardware Level 3 Block Diagram, Ultrasonic Signal Generator. .................... 30 Table 13: Hardware Level 3 Block Diagram, Transmitter Power Regulator. .................. 32 Table 14: Hardware Level 3 Block Diagram, PACU Power Unit. ................................... 34 Table 15: Hardware Level 3 Block Diagram, Receiving Chain. ...................................... 37 Table 16: Software Level 0 Block Diagram. .................................................................... 39 Table 17: Software Level 1 Block Diagram, Motion Tracking Spotlight Interface. ........ 40 Table 18: Software Level 2 Block Diagram, Wireless Transmitter. ................................. 41 Table 19: Software Level 2 Block Diagram, Sensors. ...................................................... 42 Table 20: Software Level 2 Block Diagram, PACU. ........................................................ 43 Table 21: Software Level 3 Block Diagram, Timing Information Generator. ................. 44 Table 22: Software Level 3 Block Diagram, Position Calculator. ................................... 45 Table 23: Software Level 3 Block Diagram, Timestamp Relay. ...................................... 46 Table 24: Software Level 4 Block Diagram, Timestamp Generator. ............................... 47 Table 25: Software Level 4 Block Diagram, ToA Calculator. ......................................... 48 Table 26: Software Level 4 Block Diagram, Position Calculator. ................................... 50 Table 27: Software Level 4 Block Diagram, DMX Formatter. ........................................ 51 Table 28: Parts List for Transmitter, Sensor and PACU. ................................................. 52 Table 29: Resistor, Capacitor and Inductors for Transmitter, Sensor and Receiver. ........ 53 Table 30: Budget Allocation per Device. ......................................................................... 54 Table 31: Preliminary Design Gantt Chart. ...................................................................... 55 Table 32: Implementation Gantt Chart. ............................................................................ 56

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Abstract Moving-head (or moving-yoke) spotlights are in wide use in the entertainment, live performance industry. The full utilization of these moving-head spotlights has been limited by their ability to only move to preprogrammed locations. A technology which allows for real-time modification of the light’s position, such that it can “follow” a moving object would provide performances with a new set of creative uses for these pieces of hardware. Many location positioning techniques are known today, but the relatively small size of these performance spaces merits the use of a Time of Arrival locating method using a slow-propagating wave such as ultrasound. The Time of Arrival method requires synchronization between the target being located and the receivers. This synchronization warrants the use of another wireless technology such as ZigBee wireless. Together, ZigBee and ultrasound can provide accurate position locating. Once the location of the target is known, a moving-head spotlight can be directed to the corresponding position in real-time. This new use for existing moving-head spotlights could revitalize and revolutionize the live performance lighting industry for performers, light technicians and audience members alike. Key Features of the Motion Tracking Interface for use with Moving-Head Spotlights:

• Real-time motion tracking • Acts as an interface for moving-head lights to follow a moving object • No modification to the moving-head light needed • Easy user interface

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1. Problem Statement

Need In the current world of live concert performances, moving-head spotlights are in wide use. However, the full potential of these devices has not yet been realized. Lights such as the one seen in Figure 1 (often referred to as “intelligent lighting”) can move on two axes with high levels of speed and accuracy. Presently, industry standard spotlights are human-operated and intelligent lighting is pre-programmed with set locations. There is a need for more versatility and wider creativity in moving object tracking for use in performance as well as in other industries. This project aims at live, staged performance lighting systems seeking to follow a performer/presenter on a stage. This requires precise tracking of a single object: not just anything moving in the area of operation. A system with the aforementioned capabilities will need to be easy to setup and operate.

Figure 1: Q-Spot™ 560-LED by Chauvet [1].

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Objective The objective is to design and implement a working system that provides real-time wireless motion tracking light control. The system will use a wireless transmitter placed on the moving object (person) and use ultrasonic transmission with lateration to determine the position of the object to be tracked. In order for accurate synchronization between the transmitter and receiving system, a ZigBee wireless signal will be used. The motivations for this will be explained later in this document. An interface will interpret the position data and relay the appropriate coordinate information to the moving-head hardware (intelligent light). This interface will be referred to as the Processing and Control Unit (PACU). The light will respond to the data given and “follow” the transmitter. The data obtaining/processing sequence is shown in Figure 2. The setup concept drawing is shown in Figure 3.

Moving-Head Spotlight

Person with Ultrasonic

Transducer(s) and ZigBee radio

Receiving Sensor 1

Receiving Sensor 2

Receiving Sensor 3

Processing and Control Unit (PACU)

Calculates position of

Person

Light tracks motion of person

via system position

calculation

UltrasonicTransducer

ZigBee transmitting

radio

ZigBee receiving

radio

Figure 2: Data Acquisition and Processing Diagram.

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Figure 3: Stage Stalker Setup Concept Drawing.

Background

Position-Locating Methods

Received-Strength Signal Indicator In order to evaluate the feasibility of the proposed project, research was done on a variety of small-scale motion tracking systems. K. Aamodt evaluates the success of Texas Instruments in implementing a system using ZigBee transmitters and receivers, which use reference nodes and a blind node to measure the “Received Signal Strength Indicator” values in an application note published by TI. These “RSSI” values are inversely proportional to the distance between the reference nodes and the blind node. The blind node takes all the RSSI values from known locations of reference nodes to coordinate its own position. It then transmits its calculated position data to a software platform. The system works in a two-dimensional X, Y plane, but has added Z (vertical direction) capabilities limited to floor-level distinctions, such as might be used in a multi-level building. The system has been demonstrated to have accuracy of 1 to 3 meters by TI engineers and other researchers. RSSI is a technology that has accuracy greatly affected by changes in the medium, such as moisture in the air, as well as physical impairments such as structures and people. The accuracy, as well as a slow refresh rate makes this technology less than ideal for this project.

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Time Difference of Arrival and Time of Arrival Among position-locating techniques, “Time Difference of Arrival” (TDOA) schemes give the best accuracy for the least amount of hardware synchronization. The “difference” in TDOA comes from the idea that all measurements are relative to one another. In a simple “Time of Arrival” (TOA) scheme a wireless transmitter needs to be perfectly synchronized to the receiver in order for proper distance calculations to take place because only two quantities are used to calculate the position of the target: the speed of the communication signal and the time that the (time stamped, or perfectly synchronized) signal arrived. A circle of possible locations for the target are made from this information, and their intersection is established as the location of the target. This approach is seen in Figure 4. This method often yields accuracy greater than any other positioning scheme, but can be difficult to implement due to clock drifts between the transmitters and receivers.

Figure 4: Time of Arrival Method [2].

A time difference of arrival method does not require the synchronization of transmitters and receivers. In this method, the signal from a point X is received at the time-synchronized receivers A, B and C at three different times. The different time information can then be processed by a mathematical approach such as hyperbolic-lateration. This requires a minimum of three time-synchronized receivers. The possible location of the wireless target is pinpointed to a location on hyperbolas calculated using the difference between arrival times between two receivers. The network of hyperbolas should yield an intersection: this point is the theoretical location of the target, X, as is seen in Figure 5. Use of more than three receivers is encouraged for added accuracy and error reduction.

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Figure 5: Time Difference of Arrival Method [2].

Ultra-Wideband Another technology being used for positioning is ultra-wideband. Ultra-wideband originally started as a radio technology that has since been adapted to other uses as well. It is primarily used at very low energy levels over a short range with a high bandwidth, but other applications have been tested as well. One such application, implemented by Multispectral Solutions, Inc. and the Naval Facilities Engineering Service Center, involved tracking containers in a shipping yard/warehouse. The containers were marked with an ultra-wideband tag that would specify their identity and allow for the system to keep track of them. With these relatively stationary objects, the information packets were able to be sent out about every five seconds and the accuracy for locating the tags was within a few feet. The refresh rate of this application is not high enough for a moving spotlight application. The high frequencies used for ultra-wideband and the high cost of circuit board development prevent the use of this technology for the motion tracking spotlight project.

Cell of Origin Cell of Origin is another location technology intended for cell phone and cell phone tower usage. The target area is divided into “cells” or grids with fixed parameters and a target can be located to which cell it is in based on its signal strength. This technology is very fast at determining location, without having to implement complicated positioning algorithms. However, the accuracy is not good enough for the spotlight application since positioning information can only be specified for in which cell the target is located. An illustration of Cell of Origin use can be seen in Figure 6.

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Figure 6: Cell of Origin Method [2].

Angle of Arrival Angle of Arrival location tracking is a technology that uses geometric relationships to estimate the intersection of two or more lines calculated by electronic switching instead of complex computations. This technology uses time difference of arrival calculations in determining the angle of the transmitter to the receiver. These angles can then be interpreted to find the precise location of the transmitter, since the receiver locations are known. The algorithms for angle of arrival are as complex, if not more so, than those used for time difference of arrival. An illustration for an example of the Angle of Arrival method can be seen in Figure 7.

Figure 7: Angle of Arrival Method [2].

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Using Ultrasound with Time of Arrival As it is seen, many different wireless schemes are used for location positioning techniques. This project will use the Time of Arrival (TOA) method due to its favorable demonstration of accuracy on the small scale. The small scale (targeting a stage/large room as opposed to large tracts of land) also requires a slower propagating wave, such as ultrasound so that measurable time differences may be seen between different receivers located on the stage. Ultrasound is a sound wave so it travels much slower (around 340 meters per second) than electromagnetic waves. Using TOA with ultrasound will provide a higher level of accuracy in a small area than other locating techniques such as some of those which have been explained above. Ultrasonic information provided by the transmitter and receivers will only be of use with a TOA locating method if the transmitters and receivers are time-synchronized in some way. One approach for synchronization in this small scale application is to use an electromagnetic wave such as the radio waves used in Wi-Fi, Bluetooth or ZigBee, which travel much faster than ultrasound (speed of propagation of light is 3x108 meters per second) to give a reference in time for the ultrasound waves. In this scheme (using ZigBee, for example) the ultrasonic transducer and ZigBee radio output the same time-stamped signal at the transmitter at the same time. A ZigBee receiving radio receives the signal almost instantaneously. Thus, the received time for the ZigBee signal can be taken to be the time of transmission for the ultrasound signals, which are received at different times at the different receiving sensors. Using the theoretical knowledge of when the ultrasonic signal was sent (approximately equal to the time the ZigBee signal was received) the time it was received at each sensor, as well as the known location of each sensor, the location of the transmitter can be derived. Ultrasound can be used to measure distances to accuracies within 1mm and is widely used in nautical and medical measurement systems. In order to use ultrasonic signals to determine location, ultrasonic transducers are needed. An example of an ultrasonic ceramic transducer can be seen in Figure 8.

Figure 8: Ultrasonic Ceramic Transducer [4].

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Ultrasonic transducers can act as both transmitters and receivers. To create an ultrasonic signal, a voltage is applied to a transducer. This will then cause the transducer to vibrate and send off a signal as seen in Figure 9.

Figure 9: Ultrasonic Transmission [5].

Depending on the setup used, this signal will bounce off the intended object and return to the transducer, or in the case of this design, it will arrive at another transducer acting as a receiver. Upon receiving the transmitted signal, the ultrasonic wave will compress the sensor and cause a vibration. This vibration will then cause the transducer to output a voltage as seen in Figure 10.

Figure 10: Ultrasonic Receiving [5].

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Wireless Data Transmission As was explained above, other forms of wireless communication are needed for synchronization in the Time of Arrival locating method. Among wireless data methods today, the most accessible and widely used are Wi-Fi, Bluetooth and ZigBee. Along with proprietary RF schemes, PRF, these three methods are compared in Table 1. Further descriptions of the three methods then follow.

Table 1: Wireless Protocol Comparison [9].

Wi-Fi Bluetooth ZigBee PRF

Frequencies 2.4GHz and/or 5GHz 2.45GHz

915MHz (US) 868MHz (EU) 2.4GHz (global)

900MHz (US) 868MHz (EU) 2.4MHz (global)

Channels 16 @ 2.4GHz 80 @ 8GHz 79 10 @ 915MHz

26 @ 2.4GHz

16 to 79 (can be customized)

Range (Indoor) 70m

Class1=1m 20m 1000m Class2=10m

Class3=100m

Range (Outdoor) 160m 100m 100m

40 miles (with high-gain antenna)

Data Rate (Max)

54Mbits/s (with 12Mbits/s typical)

3Mbits/s 250Kbit/s @ 2.4GHZ 40Kbit/s @915MHz

721Kbit/s to 72Mbit/s

Transmission Scheme DSSS Adaptive

FHSS DSSS FHSS or DSSS

Power Sources Wired Battery/Wired Battery/Wired

Battery/Wired (industrial power source compatible)

Uses

Cable replacement, large data transfer, networking

Short distance cable replacement

Monitoring and Controlling

Cable replacement, Monitoring, Controlling, Data Transfer

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Wi-Fi Wi-Fi (IEEE 802.11b/g/n) is most commonly used in home and office environments for wireless internet, audio and compressed video. It offers high data transfer rates and is widely accessible due to multiple IEEE standards which have been employed for a number of years. Wi-Fi is not ideal for this project due to the relatively large power consumption and larger physical components. These factors would make the design and operation of a battery-operated wireless transmitter more difficult.

Bluetooth Bluetooth (IEEE 802.15.1), like Wi-Fi, is used for wireless streaming of internet, audio and video, though its data throughput is slightly less. With newer classes of Bluetooth, the range can reach up to 100 meters, but is limited by line of sight due to low penetration ability. Bluetooth has a smaller physical size and easy setup, but is not ideal for this project due to its need of line of sight for operation.

ZigBee ZigBee (IEEE 802.15.4) is the newest of these three protocols. ZigBee is ideal for this project due to several factors such as power consumption, penetration ability and its small physical size. ZigBee wireless refers to products using the ZigBee Alliance’s specification based on the IEEE 802.15.4 standard for short-range wireless. The ZigBee communication standard was designed with battery life and power consumption in mind. With a nominal duty cycle of 0.1% or less, ZigBee out performs Wi-Fi and Bluetooth in battery life stamina in most circumstances. Along with better battery life, ZigBee uses a phase-shift-key modulation pattern, which improves bit error rate and link margin over protocols such as Wi-Fi and Bluetooth. ZigBee can also utilize AES 128-bit encryption. ZigBee is often referred to as a mesh network. The IEEE 802.15.4 standard gives each node on the network a unique 64-bit identity. Within this identifier is the designation of the node as a router or an end device. There exists one coordinator in every ZigBee network. This node is normally not battery powered because it handles operations of data routing, which require it to be constantly powered. Routers are often used as a way to group end devices. They allow messages to be sent efficiently to multiple end devices of the same function or group. End devices are battery powered and are often devices such as sensors or control systems. A sample of the ZigBee network topology is seen in Figure 11. As is seen, end devices need not always connect to the coordinator via a router, but may also connect directly.

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Figure 11: ZigBee Sample Topology

ZigBee runs at 915MHz and 2.4GHz in the United States. Although its data transfer rates are slower than those of Wi-Fi and Bluetooth, they are plenty fast for the applications seen in this project: 250Kbit/s at 2.4GHz and 40Kbits/s at 915MHz. The robustness of the ZigBee specification with IEEE 802.15.4 makes it very reliable and easy to implement: great benefits to this project.

Moving-Head Lights With different lighting companies offering different specifications on the moving-head lights they produce, a table has been set up to show a brief comparison. This comparison includes three different light models from three different manufacturers. It is seen that the lights vary in price but share many similar specifications. These comparisons can be seen in Table 2.

Table 2: Moving Yoke Light Comparisons.

Image

Make/Model Chauvet Q-Spot 560 LED[1]

Omnisistem Solo 250[6]

Elation Design Spot 250 Pro[7]

List Price $1799.99 $999.99 $1799.99 Power

Consumption (120V 60 Hz)

318 W, 2.6 A 400 W 400 W

Pan/Tilt 540 / 270 degrees 370/265 degrees 630/270 degrees Beam Angle 19 degrees 12 degrees 14 degrees

Weight 44.1 lbs 40 lbs 56. lbs

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DMX512 Lighting Control Protocol An important part of the design of the motion tracking interface includes controlling a moving-head light, which is commonly facilitated through DMX512: the industry standard for lighting control. DMX512 is based on RS-485 which is a serial, asynchronous, differential data transmission protocol. This protocol can accommodate up to 512 channels (hence the name DMX512), where each channel controls the intensity of a light or one function of a light (such as movement or color) for more complex product models. Devices in a DMX512 network are connected in a daisy-chain from device to device with the last device being “terminated”. This terminator places a 110-120 Ohm, 0.5 Watt resistor across the transmission wires so that the driving signal always sees a constant load. There are two cable types used for DMX512. The first cable is essentially identical to the standard XLR cable used for microphones, which has three wires. Also, the protocol can be used on a variant cable that has five wires. A comparison of the ends of both cables can be seen Figure 12. The 5-pin cable is not widely used since pins 4 and 5 do not get used by conventional DMX hardware. Therefore, for the purposes of our project, we will be using a 3-pin DMX cable as a transmission channel. Table 3 shows the pin assignments for a 5-pin DMX cable.

Figure 12: 3 and 5-pin DMX connectors [3].

Table 3: 5-pin DMX pin assignment.

Pin Wire Signal 1 Shield Drain Ground/0V 2 Inner Conductor (Black) Data - 3 Inner Conductor (White) Data + 4 Inner Conductor (Green) Data - (Spare) 5 Inner Conductor (Red) Data + (Spare)

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DMX512 protocol dictates that the data must be contained in a packet of 5700 bits transmitted at a frequency of 250kHz (bit rate). This equates to roughly 44 packets transmitted per second and each bit measuring 4µs long. Each packet contains some header information and then the data for each of the 512 channels successive with a separation break. The timing breakdown of the bits in a DMX512 packet is seen in Figure 13, while Figure 14 below diagrams the basic structure of a DMX512 packet, and Table 4 below breaks down the meaning and duration of each section of a packet.

Figure 13: DMX512 Packet Timing.

Figure 14: Diagram of a DMX512 Packet [3].

Table 4: Functional breakdown of a DMX512 packet [3].

Element Description State Size Duration Break The Break resets the line,

signaling a new packet. LO (0) 20-250 kbits 88µs – 1 sec

Mark After Break (MAB)

The MAB signals the receiver to begin reading data.

HI (1) 2-250 kbits 8µs – 1 sec

Start Code (SC) The SC is identical in size to channel data, but always 0 in value.

Mixed 11 bits 44µs

Mark Time Between Frames

(MTBF)

The MTBF is used to space out individual data bytes. HI (1) 0-250 kbits Up to 1 sec

Channel Data (CD)

The CD carries the 8-bit DMX Value for each channel, plus one start and two stop bits.

Mixed 11 bits 44µs

Mark Time Between Packets

(MTBP)

The MTBP is used to space out entire DMX packets. HI (1) 0-250 kbits Up to 1 sec

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Marketing Requirements 1. Easy user interface 2. Easy assembly 3. Adaptable to any stage (of a certain size) 4. High-speed motion tracking in real-time 5. Act as an interface for the light to a moving object 6. Receivers must work with processor to calculate location on stage 7. Must work with one light 8. Transmitter needs to be wireless 9. Transmitter must be easily worn by a person 10. Avoids interference with other wireless devices 11. Spotlight will not need to be modified: works with existing control protocols

Objective Tree Figure 15 shows an objective tree, which orders the marketing requirements categorically.

Figure 15: Objective Tree

Motion Tracking Light Interface

Easy user interface

Transmitter must be easily

worn by a a person

Must work with one light

No necessary modification to the light

Versatility

Easy assembly

Adaptable to any

(reasonably sized) stage

High Speed Motion

Tracking

Interface for light to follow

a moving object

System calculates

position on stage in real-

time

Wireless Transmitter

Avoids wireless

interference

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2. Design Requirements Specification The marketing requirements imposed on the project bring about requirements for the design and engineering process as well. These engineering requirements are seen in Table 5 along with their corresponding marketing requirements and justifications.

Table 5: Design Requirements. Marketing

Requirements Engineering Requirements Justification

1, 9 1. The transmitter unit will be worn

comfortably by the user and will not exceed a total weight of 10lbs.

This weight will not be cumbersome to a performer.

9 2. The transmitter unit will withstand

vibrations caused by a user’s movements.

The unit will be used for performance.

1, 2 3. The transmitter must require no user calibration.

Ease of use for performer and/or set-up personnel.

1, 8, 9 4. The transmitter will operate without

physical connection (by wire) to any other unit: it will be wireless.

Current performance electronics, such as microphones, guitar transmitters, etc. are wireless.

1 5. The wireless transmitter battery life will meet or exceed 2 hours of operation.

An average performance or presentation will not exceed 2 hours without an intermission/break.

1, 10

6. The wireless transmitter will employ a data transmission technique that does not interfere, or can be configured to work with other wireless devices. It will not cause unwanted interference.

Many wireless devices are used in live performances. This unit is not allowed to cause unwanted operation of these other devices.

1, 2 7. The processing and control unit will operate on standard 120VAC.

The system must be powered from a normal wall outlet.

4, 5, 6, 11 8. The processing and control unit will

refresh the position calculation at least 22 times per second.

The refresh rate of DMX512 protocol refreshes at a rate of 44Hz – one position update per two DMX transmissions.

2, 4, 5, 7, 11

9. The processing and control unit must output information for DMX512 control of one light via a standard 3-pin XLR connector at least 44 times per second.

This is the standard communication protocol used for performance lighting. DMX512 refreshes at a rate of 44Hz.

3, 6

10. The system must be capable of tracking the transmitter’s position over a confined area defined by a 40’ x 40’ (equivalent to 12.2m x 12.2 m) square.

This is a moderately sized stage dimension.

4, 5, 6 11. The system will employ at least 3

sensors for receiving timing information from the wireless transmitter.

The Time of Arrival calculation method requires at least 3 different time data points.

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3. Accepted Technical Design

Theory of Operation A person will wear the Stage Stalker wireless transmitter, which contains a ZigBee transceiver and an ultrasonic transducer. A timestamp will be generated and transmitted at the same time on both a ZigBee and ultrasonic signal from the transmitter. In the relatively small space of the stage, the ZigBee signal will arrive at the Processing and Control Unit (PACU) almost instantly since it travels at the speed of light (3x108

m/s). The ultrasound waves will travel much slower, at the speed of sound (340 m/s), and arrive at different times to different sensors at known locations around the stage. The sensors will relay the ultrasound packets they receive directly to the PACU via ZigBee. The time of arrival of the ultrasound signal at the different sensors will then be compared to the time of arrival of the ZigBee signal at the PACU. A time of arrival algorithm will use the time of flight of the ultrasound signal from the transmitter to each sensor to calculate a radius of possible locations for the transmitter. It will calculate the intersection of possible locations from each sensor and use this as the known location of the transmitter. This location will determine the necessary pan and tilt for the moving-head spotlight, whose location is fixed with relation to the known location of each ultrasonic sensor. A control signal using DMX512 lighting protocol will be sent to light to dictate these parameters for the light’s position. The light will move to this position (pointing at the location of the transmitter) and will continue updating, and essentially, follow the person wearing the transmitter. For implementation of a Time of Arrival Method it is required that the time of transmission and reception be known. The Stage Stalker system will use ultrasonic signals for position calculation, and will use ZigBee as a reference. An ultrasonic signal with a unique identifier (a “timestamp” which is a general binary value between 0 and 255) is sent from the wireless transmitter at the same time as a ZigBee signal with the same timestamp. The ZigBee signal will arrive at the PACU almost immediately and can then be used as the time of transmission of the ultrasound. In Equation 1 below, 𝑡!" is the arrival time of the ultrasonic signal, 𝑡! is the time in which the ultrasonic signal and ZigBee signals were sent, and 𝑡!"#$%& is the travel time associated with the ultrasonic signal.

𝑡!" − 𝑡! = 𝑡!"#$%&

Equation 1: Travel Time of Ultrasonic Signal

For the ideal case, the ZigBee signal will give a 𝑡! that is the exact time that both the ultrasonic and synchronizing signals were sent, but this is not possible: there is some propagation time for the ZigBee signal as well. Due to the speed of the ZigBee signal being a finite value, there will be a travel time (𝑡!"#$%%) associated with it which will introduce a very small error into the value of 𝑡!. In this case, the value of 𝑡! is seen below.

𝑡! = 𝑡!,!"#$!% + 𝑡!"#$%%

Equation 2: Error Introduced into 𝒕𝟎

17

The value of 𝑡!"#$%% is dependent on the speed of the ZigBee signal (which is fixed at 3x108 m/s) as well as the distance the transmitter is away from the receiver (𝐿!"#$%). Using these parameters, the value of 𝑡!"#$%% can be seen below.

𝑡!"#$%% = 𝐿!"#$%𝑣!"#$%%

Equation 3: Travel Time of ZigBee Signal.

The value of 𝑡!"#$%% can also be effected by other factors such as reflections, which would mean the ZigBee signal does not go directly to the receiver. If this occurs, more error will be introduced into the value of 𝑡!. The other factor that 𝑡!"#$%& depends on is the value of 𝑡!". As with 𝑡!"#$%%, the value of 𝑡!" depends on the distance the transmitter is away from the receiver as well as the velocity of the ultrasonic signal, which is approximately 340m/s. These calculations will use 343.2 m/s, which is the ideal speed of sound in air. Using these parameters, the value of 𝑡!" can be seen in Equation 4.

𝑡!" = 𝐿!"#$%𝑣!"

Equation 4: Travel Time of Ultrasonic Signal.

Reflections and blocking are also possible sources of error with ultrasonic waves, which may be introduced into the value of 𝑡!". For the Time of Arrival method, the ultimate goal is to find the value of 𝐿!"#$% for each ultrasonic receiver. To do this, 𝑣!" and 𝑡!"#$%& are used. The equation to find 𝐿!"#$% can be seen below.

𝐿!"#$% = 𝑣!" 𝑥(𝑡!"#$%&)

Equation 5: Distance Traveled by Wireless Signals.

The value of 𝐿!"#$% will only be found after the value of 𝑡!"#$%&which is found by Equation 1. The PACU views the arrival of the ZigBee transmission from the wireless transmitter as 𝑡!, which has error introduced by the propagation time of ZigBee as seen in Equation 2. The arrival time of the ultrasonic signal at the PACU, 𝑡!", will also have the travel time of ZigBee introduced 𝑡!"#$%%,!"#$%& since the signal is relayed from each sensor to the PACU via ZigBee.

𝑡!" = 𝑡!",!!"#$% + 𝑡!"#$%%,!"#$%&

Equation 6: Error Introduced into 𝒕𝑼𝑺.

18

Although the two propagation times are not exactly equal (𝑡!"#$%% ≠ 𝑡!"#$%%,!"#$%& due to the fact that 𝐿!"#$% ≠ 𝐿!"#$%&) they are taken to be equal. This can be done because the propagation time is fast and the distance from the sensor to the PACU 𝐿!"#$%& is of the same order of magnitude as the distance from the transmitter to the PACU 𝐿!"#$% . Taking 𝑡!"#$%% = 𝑡!"#$%%,!"#$%&, the ultimate calculation of the ultrasonic travel time 𝑡!"#$%& is based on Equation 1:

𝑡!"!"#$ = 𝑡!" − 𝑡! = 𝑡!",!"#$!% + 𝑡!"#$%% − 𝑡!,!"#$!% + 𝑡!"#$%%= 𝑡!",!"#$!% − 𝑡!,!"#$!%

Equation 7: Ultrasonic Travel Time.

Both wireless signals are going to introduce some type of error into the time of travel calculation. This will ultimately introduce error into the distance calculated for each ultrasonic receiver. To illustrate how much error could be reasonably caused, some values have been chosen at random and injected into the equations discussed above. These calculations can be seen below. Per design requirement 10, the size chosen for operation is a 12.2m by 12.2m square. Depending on the location of the ultrasonic receivers, the maximum distance the person can be from a receiver may vary. For these calculations, a relatively large distance of 12.2 meters (40 feet) is chosen to illustrate a “maximum error”. The value of 𝑡!"#$%% for the chosen distance of 12.2 m (40 ft) using Equation 4 :

𝑡!"#$%% = 12.2 𝑚𝑒𝑡𝑒𝑟𝑠

3𝑥10!𝑚𝑒𝑡𝑒𝑟𝑠 𝑝𝑒𝑟 𝑠𝑒𝑐𝑜𝑛𝑑 = 4.065𝑥10!!𝑠 = 40.65 𝑛𝑠 Equation 8: ZigBee Travel Time.

This 40.65 ns is already introducing a small amount of error into the value of 𝑡!"#$%&. If the ZigBee signal does not go directly to the receiver, more error will be introduced. Using Equation 5, two values were chosen at random to illustrate extreme cases of delay relative to the speed of the ZigBee signal. The chosen values were added to the value of 𝑡!"#$%%and the induced error was calculated. The error introduced into 𝐿!"#$% by a 1 nanosecond ZigBee propagation time delay is:

(1+ 40.65)𝑥10!!𝑠𝑒𝑐𝑜𝑛𝑑𝑠 𝑥343.2 𝑚𝑒𝑡𝑒𝑟𝑠𝑠𝑒𝑐𝑜𝑛𝑑𝑠 = 1.394𝑥10!!𝑚 = 13.94 𝜇𝑚

Equation 9: 1 Nanosecond Delay ZigBee.

The error introduced into 𝐿!"#$% by a 1 microsecond ZigBee propagation time delay is:

(1+ 0.04065)𝑥10!!𝑠𝑒𝑐𝑜𝑛𝑑 𝑥343.2 𝑚𝑒𝑡𝑒𝑟𝑠𝑒𝑐𝑜𝑛𝑑𝑠 = 1.394𝑥10!!𝑚 = 0.35 𝑚𝑚

Equation 10: 1 Microsecond Delay Zigbee.

From this, it is seen that even drastic reflections or delays of the ZigBee signal (a 1 microsecond delay is significantly large with respect to the propagation time of ZigBee)

19

will not affect the distance calculation on a scale that matters to this application. The error in the distance calculation of 𝐿!"#$% would virtually go un-noticed. Another source of error for the timing measurement is the possibility that the ultrasonic signal can reflect off of other surroundings before arriving at the receiver. This would introduce some error to the distance calculation. Again, Equation 5 was used with plausible time delays to illustrate some cases of error. The error introduced into 𝐿!"#$% by a 1 microsecond ultrasonic (reflection) delay is: 1𝑥10!!𝑠𝑒𝑐𝑜𝑛𝑑 𝑥 !"!.! !"#"$

!"#$%&= 343.2𝑥10!!𝑚 = 0.342𝑚𝑚

Equation 11: 1 Microsecond Delay Transmitter.

The error introduced into 𝐿!"#$% by a 1 millisecond ultrasonic (reflection) delay is: 1𝑥10!!𝑠𝑒𝑐𝑜𝑛𝑑 𝑥 !"!.! !"#"$

!"#$%&= 343.2𝑥10!!𝑚 = 0.342𝑚

Equation 12: 1 Millisecond Delay Transmitter.

Since the speed of the ultrasonic signal is significantly slower, a larger delay than for ZigBee would be reasonable. The error distances found for the ultrasonic reflection are significantly larger, but are still not too detrimental. A distance of 30.4 centimeters would result in the spotlight not appearing directly over the person, but even this may not be noticeable depending on the beam width and mounting height of the light. If testing proves this much delay to cause poor results, this time value may be thrown out to improve the accuracy. It is nice to observe the errors caused by each wireless signal, but it is much more meaningful to find the total error resulting from both. For this calculation, the more extreme time delay for each wireless signal was used. The time for the ultrasonic signal to arrive at a distance of 12.2 meters using Equation 4 is:

𝑡!" = 12.2 𝑚𝑒𝑡𝑒𝑟𝑠

343.2 𝑚𝑒𝑡𝑒𝑟𝑠 𝑝𝑒𝑟 𝑠𝑒𝑐𝑜𝑛𝑑 = 0.0355𝑠 Equation 13: Max Signal Arrival Time.

Adding 1 millisecond to 0.0355 seconds will result in a total time of 0.0365 seconds. Recall, the travel time of the ZigBee signal was 40.65 nanoseconds. Adding 1 microsecond to that value results in total travel time of 1,040 nanoseconds. Using Equation 1 gives the apparent travel time of both wireless signals.

𝑡!"#$%& = 0.0364 – 0.000001040 = 0.036401040𝑠 Equation 14: Travel Time of Both Signals.

The calculated distance for this situation can be found using Equation 5.

𝐿!"#$% =343.2 𝑚𝑒𝑡𝑒𝑟𝑠

𝑠𝑒𝑐𝑜𝑛𝑑 𝑥 0.036401040 𝑠𝑒𝑐𝑜𝑛𝑑𝑠 = 12.526 𝑚𝑒𝑡𝑒𝑟𝑠

Equation 15: Distance Based on Travel Time.

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The stage area to be covered is a 12.192m by 12.192m square (40’ by 40’). From this, it is seen that reflections will not affect the distance calculation so long as reception of ultrasonic data points is timing-limited. This means that an ultrasonic signal data point will be neglected if it arrives enough time after the ZigBee sync pulse is received. With such a square (12.192m by 12.192m), the greatest distance the wireless transmitter can be from any sensor is 17.242m (from one corner of the square to the opposite corner: the diagonal of the square). Therefore, the longest Time of Arrival possible is 0.0507sec (approximately 51ms using a 340 m/s speed of ultrasonic propagation rate) as shown in Equation 16.

𝑡!"# =17.242𝑚340 𝑚 𝑠 = 0.0507 𝑠𝑒𝑐 ≅ 51𝑚𝑠

Equation 16: Maximum ultrasonic propagation time.

Because the longest possible Time of Arrival is approximately 51ms, the time between ultrasound packet transmissions should be about 51ms which translates to a frequency of about 19.71Hz. This will be rounded to 22Hz for proportionality to DMX512 standards. In order to conform to the standards used by the spot light which uses DMX, packets containing data for 512 channels must sent out at 44Hz. To meet this requirement, the ultrasound packets will be transmitted at 22Hz, and then each position calculation will be transmitted to the light for two consecutive DMX control signals. A frequency of 22Hz translates to a period of 45.45 ms for each ultrasound packet. This period is acceptable since the longest possible Time of Arrival of 51ms is a rare, essentially impossible case with twelve sensors in the sensor grid. Here, the length of an ultrasound packet will be 40ms, leaving 5.45ms as downtime between transmissions. The Ultrasound packet will consist of sixteen bits: a six bit header, the eight bit message (timestamp), and two bits for error checking. This translates to a period of 2.5 ms per bit as shown in Equation 17 below.

𝑇!"# =40𝑚𝑠16 𝑏𝑖𝑡𝑠 = 2.5𝑚𝑠 𝑏𝑖𝑡

Equation 17: Period of one ultrasonic bit.

The ultrasonic transducers on the wireless transmitter will be excited at a frequency of 40kHz which translates to a period of 25µs as shown in Equation 18 below.

𝑇!"#$%%&'$!( =1

𝑓!"#$%%&'$!(=

140𝑘𝐻𝑧 = 25𝜇𝑠

Equation 18: Period of oscillation of ultrasonic transducer.

The comparator on each of the sensors needs a resolution of at least 20 cycles per bit for acceptable operation. Equation 19 shows that with a bit period of 2.5 ms per bit and a period of oscillation from the ultrasonic transducer of 25µs, a resolution of 100 cycles per bit is achieved.

𝑅𝑒𝑠𝑜𝑙𝑢𝑡𝑖𝑜𝑛 =2.5𝑚𝑠 𝑏𝑖𝑡25𝜇𝑠 = 100 𝑐𝑦𝑐𝑙𝑒𝑠 𝑠𝑒𝑐

Equation 19: Bit resolution.

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Block Diagrams

Hardware Block Diagrams Figure 16 shows the hardware level 0 block diagram, which gives a basic summary of the inputs and outputs of the system. These characteristics are described in greater detail in the hardware level 1 block diagram seen in Figure 17. A more in depth description of the transmitter, sensors and PACU can be seen in Figure 18, Figure 19 and Figure 21, respectively. The level 3 hardware block diagrams can be seen in Figure 30, Figure 32 and Figure 35, with schematics after each.

Figure 16: Hardware Level 0 Block Diagram, Motion Tracking Spotlight Interface.

Table 6: Hardware Level 0 Block Diagram, Motion Tracking Spotlight Interface.

Module Motion Tracking Spotlight Interface, Hardware Diagram

Designer Eric Hillen Inputs VDCT: +12.8VDC used to power

components in the Motion Tracking Spotlight Interface. VDCS1: +3.3VDC used to power components in the Motion Tracking Spotlight Interface. VDCS2: +3.3VDC used to power components in the Motion Tracking Spotlight Interface. VAC: +120VAC (wall power) used to power components in the Motion Tracking Spotlight Interface.

Outputs DMX512 Position Signal to Spotlight: Signal sent to moving head spotlight corresponding to a position.

Description The Motion Tracking Spotlight Interface takes in a DC and an AC voltage that is used to power the Wireless Transmitter, Sensors and PACU. These components are used to determine the location of the transmitter.

Motion Tracking Spotlight InterfaceDMX512 Position Signal to

Spotlight

VDCT

VAC

VDCS1

VDCS1

22

Figure 17: Hardware Level 1 Block Diagram, Motion Tracking Spotlight Interface.

Table 7: Hardware Level 1 Block Diagram, Motion Tracking Spotlight Interface.

Module Motion Tracking Spotlight Interface, Hardware Diagram

Designer Eric Hillen Inputs VDCT: +12.8VDC used to power components

in the Wireless Transmitter. VDCS1: +3.3VDC used to power components in the Sensors. VDCS1: +3.3VDC used to power components in the Sensors. VAC: +120VAC (wall power) used to power the PACU.


Description The Wireless Transmitter transmits a ZigBee signal to the PACU to identify the signal being transmitted. At the same time the ultrasonic signal is being transmitted. Once the ultrasonic signal is received at the Sensors, another ZigBee signal is being sent to the PACU from the Sensors. Upon arrival of both the Wireless Transmitter and Sensors ZigBee signals, a position can be determined by the PACU.

Wireless Signal (Ultrasound)


DMX512 Signal to Spotlight

Sensors

PACU

Wireless Signal (ZigBee Transmit)

VAC

Motion Tracking Spotlight Interface

Wireless Signal (ZigBee Distance)

VDCT

VDCS1

VDCS2

23

Figure 18: Hardware Level 2 Block Diagram, Wireless Transmitter. Table 8: Hardware Level 2 Block Diagram, Wireless Transmitter.

Module Wireless Transmitter, Hardware Diagram Designer Eric Hillen Inputs VDCT: +12.8VDC used to feed the

Transmitter Power Regulator. Outputs Wireless Signal (Ultrasound): Ultrasonic

Signal to be received by Ultrasonic Receiver. Wireless Signal (ZigBee Transmit): ZigBee Signal to be received by the ZigBee Transceiver.

Description Takes in +12.8VDC from a series connection of batteries, regulates that voltage and powers the rest of the Wireless Transmitter circuitry. The circuitry creates an identifier signal that is fed into the ZigBee Transmitter and encoded on a signal that is fed into the Ultrasonic Signal Generator.

Transmitter Intelligence


VDCT Transmitter Power Regulator

Ultrasonic Signal Generator

ZigBee Transmitter

Power Switch

Ultrasound Intelligence

Regulated DC Timer Power

Regulated DC Transmitter

Power

Regulated DC Transmitter Intelligence

Power

ZigBee Intelligence

Wireless Signal

(Ultrasound)

Wireless Signal (ZigBee Transmit)

24

Figure 19: Hardware Level 2 Block Diagram, Sensors. Table 9: Hardware Level 2 Block Diagram, Sensors.

Module Sensors, Hardware Diagram Designer Kevin Gerhart Inputs Wireless Signal (Ultrasound): Ultrasonic

Signal that is received by the Ultrasonic Receiver. VDCS1: +3.3VDC (from battery) that is regulated to +/-10VDC to power the Receiving Chain. VDCS1: +3.3VDC (from battery) that is used to power the ZigBee Transmitter.

Outputs Wireless Signal (ZigBee Distance): ZigBee signal that contains the encoded information found on the ultrasonic signal.

Description VDCS1 is regulated to +/-10VDC and used to power the components of the Receiving Chain. VDCS2 is used to power the ZigBee Transmitter. The Sensors receive an Ultrasonic Signal and creates a digital representation of the information that was encoded on that signal. This information is transmitted using the ZigBee Transmitter to the PACU.

Sensor Power

Regulator

Sensors

Wireless Signal (ZigBee Distance)Receiving

ChainUltrasonic Receiver

Wireless Signal (Ultrasound)

Received Wireless Signal

(Ultrasound)

Regulated DC Sensor Power

ZigBee Transmitter

Digitial Distance Signal

VDCS1

VDCS2

25

Figure 20: Sensor Power Regulator, PIC and ZigBee Schematic.

The Processing and Control Unit (PACU) is the brains behind the Stage Stalker system. It coordinates all information from the sensors and transmitter and performs the calculations necessary to output a DMX-formatted signal to the moving-head light. The processing required to do these calculations quickly cannot be accomplished with a PIC microcontroller so an FPGA will be used. Because the code for the FPGA is not yet fully developed, it is difficult to predict the size and memory needs for the device. Once the code is developed, the VHDL will require a certain number of logic gates and this will dictate which FPGA is used in the implementation of the design. For now, a Xilinx XC6SLX9-2TQG144C, shown in Figure 22, has been chosen as an FPGA. The PACU FPGA will need to be able to interface with multiple communication protocols to accomplish the desired functionality. The time of arrival signals from the sensors and the reference signal from the wireless transmitter will be transmitted using ZigBee to the master node on the PACU. These ZigBee signals will be interpreted by the ZigBee module, (Microchip’s MRF24J40MA) shown in Figure 24, and sent to the FPGA. This ZigBee module will interface with the FPGA using SPI (serial peripheral interface). The FPGA will also be generating the DMX512 (RS-485) signal to be sent to the spot light. Therefore, the FPGA will need to be able to interface with an RS-485 driver: a MAX485CSA+ has been chosen for this application and is shown in Figure 23. RS-485 is a protocol that is implemented using UART; hence, the FPGA will need a UART interface. The PACU will be powered from a standard wall outlet. For a clean DC voltage supply to the PACU electronics, a Mean Well PS-25-12 switching power supply will be used. This will output 12VDC, which will then be regulated to 3.3VDC and 5VDC.

26

Figure 21: Hardware Level 2 Block Diagram, PACU. Table 10: Hardware Level 2 Block Diagram, PACU.

Module PACU, Hardware Diagram Designer Ben Cochran Inputs Wireless Signal (ZigBee Distance): ZigBee

signal sent from the Sensors containing the encoded information its received ultrasonic signal. Wireless Signal (ZigBee Transmit): ZigBee signal sent from the Wireless Transmitter to the PACU to indicate a transmission has occurred. VAC: 120VAC (wall power) that is converted into DC power to power the PACU.


Description 120VAC is received from the wall and converted into desired DC voltages used to power the PACU’s components. The PACU receives each ZigBee signal and passes them to the FPGA. The FPGA records the time that each signal was received and uses that information to calculate a position. A corresponding position is determined and sent to the DMX Driver. The DMX Driver sends that position to the moving head spotlight using the correct DMX 512 format.

ZigBee Transceiver

PACU

Regulated ZigBee Transceiver Power

VAC PACU Power Unit

FPGA

Wireless Signal (ZigBee Distance)

Regulated FPGA Power

DMX512 Signal to SpotlightReceived Wireless

Signals (ZigBee)

Wireless Signal (ZigBee Transmit) DMX Driver

DMX Position Signal

Regulated DMX Driver Power

27

Figure 22: PACU FPGA Schematic.

Figure 23: PACU DMX Driver.

Figure 24: PACU ZigBee Module.

28

One of the essential parts to this design is the operation of the ultrasonic transducers. Ultrasound attenuates at a rapid rate in air. This causes great difficulty when trying to transmit over longer lengths. To accomplish this feat, multiple steps can be made. The US1640 Ultrasonic Transducers have a center frequency at 40kHz. This means that they will transmit their maximum distance if transmitted at a 40kHz rate. This idea in combination with a high driving voltage, will give a greater transmitting distance. The initial step to transmitting the ultrasonic signal is to encode an identifier on the signal. This is accomplished with a PIC18F25K20, shown in Figure 26. Using the PWM mode of the PIC, a non-periodic set of pulses can be created to represent a binary value. The binary value, given a time per bit and time per packet, will represent the identifier chosen. This binary value is not chosen so that it allows for the transmission rate of 40kHz. To do this, a timer is used to mix a 40kHz signal with the output of the PIC. As seen in Figure 26 there are a few components that are available to be varied. These two resistors and connecting capacitor determine the duty cycle and the frequency of the oscillated signal. A simple calculation needed to be made to determine what values were optimal for this design. The two equations used to determine resistor and capacitor are:

𝑇! = 0.69𝑥𝑅!𝑥𝐶! Equation 20: Time LO calculation.

𝑇! = 0.69𝑥 𝑅! + 𝑅! 𝑥𝐶! Equation 21: Time HI calculation.

Using the total time period of a 40kHz signal, a duty cycle of about 50% and a capacitor value of 1000pF, the value of R5 is found to be 16.3kΩ and R4 is 3.6kΩ. Using these values will give an approximate 50% duty cycle with an oscillating frequency of 40 kHz. Getting the 40 kHz oscillating frequency is only half of what needs to be done to get maximum range.

Figure 25: Hardware Level 3 Block Diagram, Transmitter Intelligence.

PIC

Transmitter Intelligence

Ultrasound IntelligenceTimerEncoded Signal

Regulated DC Timer Power

Regulated DC Transmitter Intelligence

Power

ZigBee Intelligence

29

Table 11: Hardware Level 3 Block Diagram, Transmitter Intelligence.

Module Transmitter Intelligence, Hardware Diagram Designer Eric Hillen Inputs Regulated DC Transmitter Intelligence Power:

+3.3 VDC used to power the PIC18F25K20. Regulated DC Timer Power: +5VDC used to power the LM555CM timer.

Outputs Ultrasound Intelligence: 5Vp-p signal that will be used to excite the Ultrasonic Transducer with the desired encoding. ZigBee Intelligence: Binary value sent from the PIC to the ZigBee chip that is used to identify the transmitted signal.

Description The PIC is powered by the Regulated DC Transmitter Intelligence Power and creates an identifier for the signal to be transmitted. This binary value is sent to the ZigBee chip and is encoded on a binary signal. The timer creates a 40kHz oscillation and mixes it with the binary signal. This mixed signal is used to drive the Ultrasonic Transmitter at its resonant frequency.

Figure 26: Transmitter PIC and ZigBee Schematic.

Figure 27: Transmitter Timing Schematic.

30

Figure 28: Hardware Level 3 Block Diagram, Ultrasonic Signal Generator. Table 12: Hardware Level 3 Block Diagram, Ultrasonic Signal Generator.

Module Ultrasonic Signal Generator, Hardware Diagram

Designer Eric Hillen Inputs Ultrasound Intelligence: 5Vp-p signal that is

used to excite the Ultrasonic Transducer after amplification. Regulated DC Transmitter Power: +70VDC that the peak to peak value of the Ultrasound Intelligence is amplified to.

Outputs Wireless Signal (Ultrasound): Ultrasonic Signal to be received by the Ultrasonic Receiver.

Description The Ultrasound Amplifying Circuit takes in the Regulated DC Transmitter Power to supply the MOSFETs. It takes in the Ultrasound Intelligence and amplifies it to a 70Vp-p signal. The resulting signal is fed into the Ultrasonic Transducer and output as a wireless ultrasonic signal.

Ultrasound Amplifying

Circuit

Ultrasonic Signal Generator

Wireless Signal (Ultrasound)Ultrasonic

Transducer

Amplified Ultrasound Intelligence

Ultrasound Intelligence

Regulated DC Transmitter

Power

31

Figure 29: Transmitter Amplification Schematic.

The LM555CM timer will not output nearly enough voltage to transmit to the required distance. To do this, a MOSFET switching circuit is used with a supply voltage of +70VDC. This is shown above in Figure 29. The output of the timer is the input voltage to the N-Channel MOSFET. Varying between high and low will allow the MOSFET to switch off and on. Since the output of the timer represents the encoded signal mixed with a 40 kHz oscillation, this will cause the MOSFET to output a similar waveform. The only difference is that when the input to the N-Channel MOSFET is high, the output is low. When the input to the N-Channel MOSFET is low, the output is high. This results in an inverted signal. To account for this, the output of the N-Channel MOSFET is fed into the input of a P-Channel MOSFET. When the input to the P-Channel MOSFET is low, the output is high. When the input is high, the output of the MOSFET is low. Combining the MOSFETS in this fashion allows for the higher voltage and it outputs the same waveform that was input into the N-Channel MOSFET. The resulting signal allows for a higher driving voltage and an oscillating frequency near the resonant frequency of the transducer. This signal is fed right into the ultrasonic transducer to cause excitation. To be able to create this design, multiple voltages were required to run all of the components. On the transmitting unit, there can’t be any wires so it all needs to be run off of batteries. The amount chosen to use was four. The particular batteries are rated for +3.2VDC so a series combination of four batteries will result in a +12.8VDC supply. None of the components used by the transmitter use this particular voltage. To supply all of the voltages needed, multiple voltage regulators were used. One of the voltages required is +3.3VDC. This voltage is used to power the PIC18F25K20 and the MRF24J40MA. To arrive at this voltage the LTC1474CS8-3.3 step down regulator was used. Another voltage needed was +5VDC. This voltage was used to supply the LM555CM timer. An LM7805 step down regulator was used to take the initial +12.8VDC down to the required +5VDC. The more important voltage is the +70VDC used to amplify the Ultrasound Intelligence. As mentioned, the +70VDC is used to pull up the original Ultrasound Intelligence signal to a higher voltage. To accomplish this, the

32

LM5001 boost regulator was used. It takes the +12.8VDC from the batteries and regulates the voltage to +70VDC. The components of the Wireless Transmitter used in this design require little power. The batteries chosen are rated at 3.2V, 8A and 800mAh. This allows for the series connection to supply power to all of the voltage regulators.

Figure 30: Hardware Level 3 Block Diagram, Transmitter Power Regulator. Table 13: Hardware Level 3 Block Diagram, Transmitter Power Regulator.

Module Transmitter Power Regulator, Hardware Diagram

Designer Eric Hillen Inputs VDCT: +12.8VDC (from battery) that is

regulated to a +3.3VDC, +5VDC and +70VDC signal used by transmitter components.

Outputs Regulated DC Timer Power: +5VDC used to power the LM555CM timer. Regulated DC Transmitter Intelligence Power: +3.3VDC used to power the PIC18F25K20 and the ZigBee transmitter. Regulated DC Transmitter Power: +70 VDC used to amplify the Ultrasound Intelligence.

Description +12.8VDC supplied by a series of batteries is regulated to three different voltages. +70VDC to supply the MOSFET amplifying circuit, +5VDC to power the LM555CM timer and +3.3VDC to power the PIC18F25K20 and the ZigBee transmitter.

Transmitter Power Regulator

Regulated DC Timer PowerTimer Power Regulator

VDCT Intelligence Power Regulator

Transmitter Power Regulator

Regulated DC Transmitter Intelligence Power

Regulated DC Transmitter Power

33

Figure 31: Transmitter Power Regulator Schematic.

34

Figure 32: Hardware Level 3 Block Diagram, PACU Power Unit. Table 14: Hardware Level 3 Block Diagram, PACU Power Unit.

Module PACU Power Unit, Hardware Diagram Designer Ben Cochran Inputs VAC: 120VAC (wall power) that is regulated

to +12VDC. Outputs Regulated ZigBee Transceiver Power:

+3.3VDC used to power the PIC18F25K20. Regulated FPGA Power: Used to power the FPGA. Regulated DMX Driver Power: Used to power the DMX Driver.

Description 120VAC is converted to +12VDC using a Mean Well PS-25-12. The +12VDC is regulated to voltages required by PACU components. These voltages include +3.3VDC and +5V. These voltages are used to power the PIC18F25K20, the FPGA and the DMX Driver.

AC to DC Converter

PACU Power Unit

Regulated ZigBee Transceiver PowerZigBee Power Regulator

VAC FPGA Power Regulator

DMX Driver Power Regulator

Regulated FPGA Power

Regulated DMX Driver Power

VADC

35

Figure 33: PACU Power Unit Schematic.

The goal of the receive chain with band pass filters, seen in Figure 35 and Figure 36, is to drive the input ultrasonic signal, which will be in the millivolt range, to the rails of the op-amp, set at 10V. After the input has been amplified, the envelope detector will detect the rising edge and create a continuous, smooth signal, which will allow the comparator to easily convert the ultrasonic pulses into a digital signal. This signal will then be fed into the PIC, which will use SPI to transmit the received ultrasonic information to the PACU using ZigBee. The first part of the receive chain includes an active band-pass filter. The resonant frequency of the ultrasonic transducers in the wireless transmitter is 40kHz so the signal received will be a modulated pulse using a 40kHz carrier wave. For this reason, the received signal information will be centered at 40kHz. In order to eliminate noise, and focus the amplification of the received signal on the actual signal information, a Sallen-Key band-pass filter will be implemented. Below, Figure 34 shows the schematic of a Sallen-Key band-pass filter, and Equation 22 defines the mid-frequency of the filter.

Figure 34: Sallen-Key Band-Pass Filter Topology.

36

The desired mid-frequency for this Sallen-Key band-pass filter in the ultrasonic sensor circuit is 40kHz. Therefore, to find 𝑅, 𝐶 is chosen arbitrarily to be 1000𝜌𝐹 which results in a value of 3.97𝑘Ω for 𝑅.

𝑓! =1

2𝜋𝑅𝐶 Equation 22: Mid-Frequency of Sallen-Key BP Filter.

The Sallen-Key band-pass also acts as the first amplification stage. Equation 23 defines the inner gain of the filter to be a function of the two resistors 𝑅! and 𝑅!. In order to maintain a reasonable quality factor (Q) for the filter, the inner gain, 𝐺, must be less than a value of 3. This is because the gain at 𝑓! (called 𝐴!) approaches infinity and the circuit begins to oscillate as it approaches 3; therefore, a value of 2.5 is chosen for 𝐺. For 𝐺 = 2.5, logical values are chosen to make 𝑅! = 10𝑘Ω and 𝑅! = 15𝑘Ω.

𝐺 = 1+𝑅!𝑅!

Equation 23: Inner Gain.

Equation 24 shows the relationship between the gain at the mid-frequency with the inner gain, 𝐺 = 2.5, which gives a value of 5 for 𝐴!.

𝐴! =𝐺

3− 𝐺 =2.5

3− 2.5 = 5𝑉 𝑉 Equation 24: Mid-Frequency Gain.

Based on preliminary testing, the minimum accepted received voltage will be approximately 10mV. Anything less than this value will be considered noise. In order to amplify this voltage to saturate the third op amp in the amplifier chain, a gain of 500 V/V (for the whole chain) will be implemented. A gain of 500 V/V will mean an input of .01V (10mV) will output 5V at the end of the chain, which is higher than the reference voltage of the comparator and therefore a logical value. The second stage of the receive chain is a non-inverting amplifier. The gain of this non-inverting operational amplifier circuit is given in Equation 25. To allow for another identical Sallen-Key band-pass and amplification stage with a gain of 5V/V as the final amplification stage, and still get a gain of 500 V/V overall, a second stage gain of approximately 20 V/V is needed. To achieve this, 𝑅! is set to 1𝑘Ω and 𝑅! is set to 19.1𝑘Ω.

𝐺𝑎𝑖𝑛 = 1+𝑅!𝑅!

= 1+19.1𝑘Ω1𝑘Ω = 20.1𝑉 𝑉

Equation 25: Op-amp Gain.

Using the gain of the two band pass filters, each with a gain of 5V/V and the gain of the Non-inverting Operational Amplifier, which is 20.1V/V, the gain will be approximately 500V/V from:

𝐺𝑎𝑖𝑛 = 5×20.1×5𝑉 𝑉 = 502.5𝑉 𝑉 Equation 26: Total Gain of the Received Chain.

37

In order to bias the op-amps in the receive chain, +/-10VDC is needed. The input voltage is coming from a 3.3V battery. The LT1615 gives positive and negative selectable output voltages. Equation 27 shows the values of the resistors needed based on the desired output. Manipulating the given equation for 𝑉!"# = 10𝑉, Equation 28 shows the resulting value for the ratio of the resistors. Using large resistor values, as recommended, R1 = 856kΩ and R2 = 120kΩ.

𝑅! = 𝑅!(𝑉!"#1.23− 1)

Equation 27: Resistor Values based on Output Voltage. 𝑅!𝑅!

= 7.13 Equation 28: Resistor Ratios.

Figure 35: Hardware Level 3 Block Diagram, Receiving Chain. Table 15: Hardware Level 3 Block Diagram, Receiving Chain.

Module Receiving Chain, Hardware Diagram Designer Kevin Gerhart. Inputs Received Wireless Signal (Ultrasound): The

output of the Ultrasonic Receiver. Outputs Digital Distance Signal: Digital representation

of the interpreted signal encoded on the ultrasonic signal that is being sent to the ZigBee Transmitter.

Description The output of the Ultrasonic Receiver is taken in, filtered using an active band pass filter with a gain of five and center frequency of 40 kHz. The filtered signal is amplified again using an amplifier with a gain of 20. The resulting signal is passed through another active band pass filter with the same characteristics of the one mentioned above. The output of this will be a “sinusoid.” This sinusoid passes through an envelope detector to give a positive voltage. This positive voltage passes through a comparator whose output should be the same as the signal encoded on the ultrasonic signal. Using SPI, this signal is passed to the ZigBee Transmitter.

Active Filter

Receiving Chain

Received Wireless Signal

(Ultrasound) Active FilterAmplfier Envelope

Detector Comparator PIC

Digital Distance

Signal

38

Figure 36: Sensor Amplifier Chain Schematic.

39

Software Block Diagrams Figure 37 shows the software level 0 block diagram, which, like the hardware level 0 block diagram, gives a basic summary of the inputs and outputs of the system. These software characteristics are described in greater detail in Table 16. The software level 1 block diagram and description of the motion tracking spotlight interface can be seen in Figure 38 and Table 17, respectively. A more in depth description of the wireless transmitter, sensors and Processing and Control Unit (PACU) can be seen in the level 2 block diagrams in Figure 39, Figure 40 and Figure 41 respectively, with a description of the components in the tables below. It follows that software level 3 block diagrams, which describe the timing information generator, position calculator and Timestamp Relay can be seen in Figure 42,Figure 43, and Figure 44 respectively, with descriptive tables below.

Motion Tracking Spotlight InterfaceDMX512 position

information to spotlight

Figure 37: Software Level 0 Block Diagram. Table 16: Software Level 0 Block Diagram.

Module Motion Tracking Spotlight Interface, Software Diagram

Designer Chris Trowbridge Inputs Outputs DMX512 position information to

spotlight: DMX512 protocol Description Calculate where to point the spot light

based on the Time of Arrival (TOA) signal data from the sensor nodes and feed the position information to the spotlight using DMX512 protocol.

40

Wireless Timing Information (Ultrasound)


DMX512 position information to spotlight

Sensors

PACU

Wireless Timing Information (ZigBee)

Digital Received Timing Information

Motion Tracking Spotlight Interface

Figure 38: Software Level 1 Block Diagram, Motion Tracking Spotlight Interface.

Table 17: Software Level 1 Block Diagram, Motion Tracking Spotlight Interface.

Module Motion Tracking Spotlight Interface, Software Diagram

Designer Chris Trowbridge Inputs Outputs DMX512 position information to spotlight:

DMX512 protocol Description Calculate where to point the spot light based on

the Time of Arrival (TOA) signal data from the sensor nodes and feed the position information to the spotlight using DMX512 protocol.

41

Timing Information Generator


Transmitter ClockWireless Timing Information

(Ultrasound)

Wireless Timing Information(ZigBee)

Figure 39: Software Level 2 Block Diagram, Wireless Transmitter.

Table 18: Software Level 2 Block Diagram, Wireless Transmitter.

Module Wireless Transmitter, Software Diagram Designer Chris Trowbridge Inputs Outputs -‐ Wireless Timing Information (Ultrasound):

Data to be embedded on the Ultrasound signal -‐ Wireless Timing Information (ZigBee): Data

to be embedded on the ZigBee signal Description Generate the timing information to embed on

the Ultrasound (for location purposes) and ZigBee signals (for synchronization purposes).

42

Timestamp Relay

Sensors

Digital Received Timing Info

(ZigBee)Wireless Timing Information

(Ultrasound) ZigBee Module

Sensor Clock

Figure 40: Software Level 2 Block Diagram, Sensors.

Table 19: Software Level 2 Block Diagram, Sensors.

Module Sensors, Software Diagram Designer Chris Trowbridge Inputs -‐ Wireless Timing Information (Ultrasound): Data

embedded on an Ultrasound signal Outputs -‐ Digital Received Timing Info: Digitized format

of the timing information sent via Ultrasound from the Wireless Transmitter

Description Receive the Ultrasound wireless timing information from the Wireless Transmitter and convert it to a digital format for location computations.

43

Position Calculator

PACU

DMX512 position information to

spotlight

Wireless Timing Information (ZigBee)

Digital Received Timing Info

PACU Clock

Figure 41: Software Level 2 Block Diagram, PACU.

Table 20: Software Level 2 Block Diagram, PACU.

Module PACU, Software Diagram Designer Chris Trowbridge Inputs -‐ Wireless Timing Information (Ultrasound): Data embedded on

an Ultrasound signal -‐ Digital Received Timing Info: Digitized format of the timing

information sent via Ultrasound from the Wireless Transmitter Outputs -‐ DMX512 position information to spotlight: Signal defining the

position of the Wireless Transmitter relative to the spotlight encoded in DMX512 protocol

Description Receive the wireless timing information (ZigBee) from the Wireless Transmitter and the digitized wireless timing information (Ultrasound) and use this data to compute the position of the Wireless Transmitter relative to the spotlight. Then, convert this position to the correct DMX512 protocol and transmit it to the spotlight.

44

TimestampGenerator

Timing InformationGenerator

Transmitter Clock

Wireless TimingInformation (Ultrasound)

Wireless TimingInformation (ZigBee)

Ultrasound Protocol

Generator

ZigBee Protocol

Generator

Figure 42: Software Level 3 Block Diagram, Timing Information Generator.

Table 21: Software Level 3 Block Diagram, Timing Information Generator.

Module Timing Information Generator, Software Diagram

Designer Chris Trowbridge Inputs -‐ Transmitter Clock: The global clock used on

the Wireless Transmitter Outputs -‐ Wireless Timing Information (Ultrasound):

Data to be embedded on the Ultrasound signal -‐ Wireless Timing Information (ZigBee): Data to

be embedded on the ZigBee signal Description Generate a timestamp and correctly encode it on

both the output signals (Ultrasound and ZigBee).

45

ZigBeeInterface

Position Calculator

DMX512position

information to spotlight

Wireless Timing Information

(ZigBee)

Digital Received Timing Info(ZigBee)

PACU Clock

ToACalculator

X, Y Relative Position

Calculator

DMX Formatter

Sensor 1 ToA

Sensor 2 ToA

Sensor 12 ToA

.

.

.

Figure 43: Software Level 3 Block Diagram, Position Calculator.

Table 22: Software Level 3 Block Diagram, Position Calculator.

Module Position Calculator, Software Diagram Designer Chris Trowbridge Inputs -‐ PACU Clock: The global clock used on the PACU

-‐ Wireless Timing Information (ZigBee): Data embedded on the ZigBee signal

-‐ Digital Received Timing Info: Digitized format of the timing information sent via Ultrasound from the Wireless Transmitter

Outputs -‐ DMX512 position information to spotlight: Signal defining the position of the Wireless Transmitter relative to the spotlight encoded in DMX512 protocol

Description Interpret the ZigBee and digitized Ultrasound signals into a useable format for computations. Then, use these signals to calculate Time of Arrival (TOA) values for each sensor. Next, use the TOA’s to compute the relative (x, y) of the Wireless Transmitter from the spotlight. Lastly, encode the relative position in DMX512 and transmit it to the spotlight.

46

The Timestamp Relay, Figure 44 , acts as a software buffer between the ADC and the ZigBee module on a sensor. When the timestamp arrives at an Ultrasound sensor, the signal is fed to an ADC (a 1-bit resolution comparator) which is then fed to the Timestamp Relay. The Timestamp Relay holds and interprets the data and then forwards it to the ZigBee module (a chip that handles the ZigBee protocol) for transmission to the PACU using SPI.

Timestamp out

Timestamp Relay

Store timestamp

Begin

Timestamp in

Forward timestamp

Figure 44: Software Level 3 Block Diagram, Timestamp Relay.

Table 23: Software Level 3 Block Diagram, Timestamp Relay.

Module Timestamp Relay, Software Diagram Designer Chris Trowbridge Inputs -‐ Sensor Clock: The global clock used on the

sensor -‐ Timestamp in: The timestamp signal coming

from the ADC on a sensor Outputs -‐ Timestamp out: The timestamp signal data

sent to the ZigBee module on a sensor Description Act as an interface for the ADC and the

ZigBee module on a sensor

47

The Timestamp Generator, Figure 45, is needed to produce a single, unique timestamp which will be transmitted using both ultrasound and ZigBee. This timestamp needs to be uniquely created so that the sensors can distinguish between incoming transmissions. A unique timestamp can be formed using an 8-bit up counter, which conveniently maps to 8-bit ASCII characters. For example, a sequence of transmissions could be ‘a’, ‘b’, ‘c’, etc. This scheme will help to deal with reflections and other error introduced by the use of ultrasound (which propagates through the air as a sound wave) because the PACU can concentrate on one timestamp at a time and reject all other transmissions received.

Timestamp Generator

count = 0

count = count + 1

count = 255?(28)

timestamp

Begin

noyes

Figure 45: Software Level 4 Block Diagram, Timestamp Generator.

Table 24: Software Level 4 Block Diagram, Timestamp Generator.

Module Timestamp Generator, Software Diagram Designer Chris Trowbridge Inputs -‐ Transmitter Clock: The global clock used on the

Wireless Transmitter Outputs -‐ Timestamp: The timestamp signal used to

uniquely identify each transmission on the PACU. Description Generate a timestamp to be transmitted on both

Ultrasound and ZigBee.

48

The ToA Calculator, Figure 46, rejects all but the four earliest arriving signals from the Ultrasound sensors. This significantly reduces the complexity of the location calculations. The first four signals are chosen because there is less noise in the earliest arriving signals (they are the closest receivers to the Wireless Transmitter and wouldn’t contain reflections). These four signals are then compared to the arrival time through ZigBee of the same timestamp. Because the Ultrasound sensors relay the timing information via ZigBee, this calculation results in an adjusted Time of Arrival measurement from each of the three significant sensors because the time delay due to the propagation of a ZigBee signal is present in both time of arrival measurements. See Figure 47 below.

ToA Calculator

Pick first 4 sensor signals to arrive

Begin

Wireless Timing Information

Sensor Timing Information

Wireless Timing Information –

Digital Received Timing Info (4)

Sensor ToA

/

/

/

12

4

4

Figure 46: Software Level 4 Block Diagram, ToA Calculator.

Table 25: Software Level 4 Block Diagram, ToA Calculator.

Module ToA Calculator, Software Diagram Designer Chris Trowbridge Inputs -‐ PACU Clock: The global clock used on the

PACU -‐ Wireless Timing Information: timestamp

arriving via ZigBee from the Wireless Transmitter

-‐ Sensor Timing Information: timestamp arriving via ZigBee from each of the 12 Ultrasound sensors

Outputs -‐ Sensor ToA: The time of arrival for each of the 4 earliest arriving sensor transmissions

Description Select only the four earliest arriving Ultrasound transmissions and compute the time of arrival for each.

49

Figure 47: ToA Signals for Calculation.

The X, Y Relative Position Calculator, Figure 48, interfaces between the ToA Calculator and the DMX formatter. This module performs the crucial task of determining where the Wireless Transmitter is based on the four Time of Arrival measurements from the sensors. These four measurements can be used to compute the radii of circles centered at each of the sensors by simply invoking the distance formula. Next, the two points of intersection for the first two circles is calculated. A check is then performed to determine if one of the points is outside of the target grid. If one point is outside the grid, by default, the other point is the approximate location of the Wireless Transmitter. If both intersection points are inside the grid, the radius of the third circle is compared to both of the points. If one point is closer to the third circle, it is normally the correct point, but some exceptions do occur. To account for these exceptions, both points are compared to the radius of the fourth circle. The correct point is the one that is closest to the third circle and furthest from the fourth circle. Based on the approximate position determined by this algorithm, the motion needed to point the spot light at the Wireless Transmitter can be calculated because the spot light is in a fixed 3-dimensional position (angle of the light beam will need to be compensated for in these calculations). This Position Calculator has been simulated in MATLAB and will be transferred to the Xilinx FPGA when it has been refined. The code for this simulation is seen in Appendix 1.

50

X, Y Relative Position Calculator

Find intersections of circles 1 and 2

Begin

Sensor ToA/4

Determine which intersection point

is closer to the third circle

/ 2

Adjust decision with fourth circle

/ 2

Calculate needed spot light motion

Spot light needed motion

Is one of the points outside the

grid?

yesno

Use the opposite

point

Figure 48: Software Level 4 Block Diagram, Position Calculator.

Table 26: Software Level 4 Block Diagram, Position Calculator.

Module X, Y Relative Position Calculator, Software Diagram

Designer Chris Trowbridge Inputs -‐ PACU Clock: The global clock used on the

PACU -‐ Sensor ToA: The time of arrival for each of

the 4 earliest arriving sensor transmissions Outputs -‐ Spot light needed motion: The 3-dimensional

movement needed to position the beam of the spot light over the Wireless Transmitter

Description Using the Sensor ToA measurements from the ToA Calculator, compute the position of the Wireless Transmitter relative to the spot light. Then, determine how the spot light needs to move and sends this data to the DMX Formatter.

51

The DMX Formatter, Figure 49, will correctly format a DMX packet based on the motion needed in all 3 dimensions (x, y, z). This module will also be responsible for ensuring that all the protocol standards are met to comply with DMX512. This is important because the spot light has been purchased by a third-party vendor and also conforms to DMX512 protocol standards.

DMX Formatter

Format motion values for DMX

(0 – 255 per channel)

Begin

Spot light needed motion

Generate DMX packet

DMX packet

Figure 49: Software Level 4 Block Diagram, DMX Formatter.

Table 27: Software Level 4 Block Diagram, DMX Formatter.

Module DMX Formatter, Software Diagram Designer Chris Trowbridge Inputs -‐ PACU Clock: The global clock used on the

PACU -‐ Spot light needed motion: The 3-dimensional

movement needed to position the beam of the spot light over the Wireless Transmitter

Outputs -‐ DMX packet: The correctly formatted DMX packet to be sent out to the spot light.

Description Correctly construct a DMX packet given how the spot light needs to move.

52

4. Parts List The parts list seen in Table 28 indicates quantities of parts need to create one transmitter, sensor and PACU circuit.

Table 28: Parts List for Transmitter, Sensor and PACU.

Qty. Refdes Part Num. Description Cost Total Cost 1 U1 MRF24J40MA-

I/RM MODULE RF TXRX PICTAIL PLUS 10.87 $ $10.87

1 U11 PIC18F25K20-I/SS IC PIC MCU FLASH 16KX16 28SSOP

1.61 $ $1.61 1 U3 LM555CM 555 Type, Timer/Oscillator

(Single) 0.45 $ $0.45

1 U9 LT1615ES5#TRMPBF IC REG BOOST ADJ 0.35A TSOT23-5 1.86 $ $1.86 1 U10 MRF24J40MA-

I/RM MODULE RF TXRX PICTAIL PLUS 10.87 $ $10.87

1 U6 TL331IDBVR IC DIFFCOMPRTR SINGLE SOT-23-5 0.14 $ $0.14 3 U4,U5,U7 LM318M/NOPB IC OP AMP HIGH SLEW RATE 8-

SOIC 1.05 $ $3.15

1 U2 MAX485CSA+ IC TXRX RS485/RS422 LOWPWR 8SOIC 3.05 $ $3.05 1 U3 LM7805CT IC REG LDO 5V 1A TO-220 0.67 $ $0.67 1 U4 LTC1474CS8-3.3#PBF IC REG BUCK 3.3V 0.75A 8SOIC 6.91 $ $6.91 1 J2 DF1BZ-4P-2.5DSA CONN HEADER 4POS 2.5MM STR TIN 0.45 $ $0.45 1 709-PS25-12 Linear and Switching Power Supplies 25.2W 12V 2.1A 22.32 $ $22.32 1 J3 NC3FBAH1 XLR Connectors 3P FEMALE CHASS HORIZONTAL 2.92 $ $2.92 1 U5 XC6SLX9-2TQG144C IC FPGA SPARTAN-6 9K 144TQFP 15.69 $ $15.69 1 D9 SMAJ6.0A DIODE TVS 6.0V 400W UNI 5% SMA 0.43 $ $0.43 1 D8 1N5236B-TR DIODE ZENER 7.5V 500MW DO35 0.42 $ $0.42 1 U7 LM7805CT IC REG LDO 5V 1A TO-220 0.67 $ $0.67 1 U4 LTC1474CS8-3.3#PBF IC REG BUCK 3.3V 0.75A 8SOIC 6.91 $ $6.91 1 U11 PIC18F25K20-I/SS IC PIC MCU FLASH 16KX16

28SSOP 1.61 $ $1.61

1 U10 MRF24J40MA-I/RM

MODULE RF TXRX PICTAIL PLUS 10.87 $ $10.87 1 U12 LM5001SD/NOPB IC REG MULTI CONFIG ADJ 1A 8-LLP 4.02 $ $4.02 1 M1 IRFL9110TRPBF MOSFET P-CH 100V 1.1A SOT223 0.79 $ $0.79 1 D1 MBR0530L-TP DIODE SCHOTTKY 0.5A 30V SOD-123 0.42 $ $0.42 2 D3,D4 BAT54-7-F DIODE SCHOTTKY 30V 200MW SOT23-3 0.16 $ $0.32 1 M2 IRFL110TRPBF MOSFET N-CH 100V 1.5A SOT223 0.74 $ $0.74 4 D4-D7 MBR0530L-TP DIODE SCHOTTKY 0.5A 30V SOD-123 0.42 $ $1.68 6 2128 Category: 18500 Cell Holders 2.74 $ $16.44 1 D1 1N4148-TAP DIODE SWITCH SS 75V 300MA DO35 0.23 $ $0.23 1 FN9263S-3-06 AC Power Entry Modules 3A 250VAC 50/60Hz Snap-in vertical 12.48 $ $12.48

$138.99

53

The parts list seen in Table 29 includes all other components for which pricing and exact part number is not as crucial as other IC’s.

Table 29: Resistor, Capacitor and Inductors for Transmitter, Sensor and Receiver.

Qty. Refdes Part Num. Description Cost Total Cost2 7.94k ohm resistor $0.004 3.97k ohm resistor $0.005 10k ohm resistor $0.004 15k ohm resistor $0.001 25k ohm resistor $0.001 19.1k ohm resistor $0.005 1k ohm resistor $0.001 40 ohm resistor $0.001 856k ohm resistor $0.001 120k ohm resistor $0.005 100k ohm resistor $0.001 1.5k ohm resistor $0.002 0 ohm resistor $0.001 5k ohm resistor $0.001 1M ohm resistor $0.001 20.5k ohm resistor $0.001 20 ohm resistor $0.001 49.9 ohm resistor $0.001 66.5k ohm resistor $0.001 10 ohm resistor $0.001 69.8k ohm resistor $0.001 6.8 ohm resistor $0.001 76.8k ohm resistor $0.001 1.27k ohm resistor $0.0013 1000pF capacitor $0.001 10000pF capacitor $0.002 4.7uF capacitor $0.005 1uF capacitor $0.001 4.7pF capacitor $0.003 10uF/20V capacitor $0.003 10uF/10V capacitor $0.003 100uF/10V capacitor $0.002 1nF capacitor $0.001 10uF/25V capacitor $0.001 15uF/25V capacitor $0.004 10nF capacitor $0.001 100nF capacitor $0.001 5.1pF capacitor $0.001 470pF capacitor $0.001 33nF capacitor $0.001 1uF/10V capacitor $0.001 10uF capacitor $0.002 10uH inductor $0.003 100uH inductor $0.001 150uH inductor $0.001 Intimidator Spot LED 250 40-watt LED-based Moving-yolk Spotlight Lighting Fixture 599.99$ $599.99

Total $599.99

54

The budgeting seen in Table 30 shows the price for each individual circuit. Only one transmitter and PACU will need to be built, but several sensors will need to be built. This shows that this will be feasible with the budget allowed for this project.

Table 30: Budget Allocation per Device.

Transmitter Cost $ 37.76 % of Budget 4.72%

Sensor Cost $ 20.39 % of Budget 2.55%

PACU Cost $ 75.36 % of Budget 9.42%

Total Project Cost $ 133.51 % of Budget Used 16.69%

Money Remaining $ 666.49

% of Budget Remaining 83.31%

55

5. Project Schedules The project duties which have been assigned to each member are summarized in Table 31 below. This Gantt chart shows the design research considerations that have been taken (and by whom) thus far. The Gantt chart in Table 32 shows the design steps that will be taken to implement the design.

Table 31: Preliminary Design Gantt Chart.

56

Table 32: Implementation Gantt Chart.

57

58

6. Design Team Information Ben Cochran, Electrical Engineering. Kevin Gerhart, Electrical Engineering. Eric Hillen, Electrical Engineering. Chris Trowbridge, Computer Engineering.

7. Conclusions and Recommendations This project will use knowledge of signal processing, control systems, circuit design, embedded systems, user-interface design and microprocessor programming. Background knowledge in all of these topics is beneficial to new engineers. The project will require time management, planning and timely execution in order to achieve a favorable outcome.

59

8. References Aamodt, K. Application Note CC2431 Location Engine. Tech. no. AN042. N.p.: Texas Instruments, 2006. Print. Adams, Jon T. ZigBee Wireless Technology and the IEEE 802.15.4 Radio-Enabling Simple Wireless. N.p.: Freescale Semiconductor, Inc., n.d. PDF. [3]"DMX 101 Handbook." Elation Lighting, n.d. Web. 1 Oct. 2012. <www.elationlighting.com/pdffiles/dmx-101-handbook.pdf>. [7]"Elation Professional - Professional Lighting Products." Elation Professional - Professional Lighting Products. N.p., n.d. Web. 14 Oct. 2012. <http://www.elationlighting.com/ProductDetails.aspx?ItemNumber=1508>. Fontana, Robert J., and Steven J. Gunderson. "Ultra-Wideband Precision Asset Location System." 2002 IEEE Conference on Ultra Wideband Systems and Technologies (2002): n. pag. Print. [9] "Industrial Wireless - Selecting a Wireless Technology." B&B Electronics: Tech Notes. B&B Electronics, n.d. Web. 12 Oct. 2012. <http://www.bb-elec.com/tech_articles/industrial_wireless.asp>. [4] Long-Range Ultrasonic Sensor. Digital image. Futurlec Electronic Components Superstore. Futurlec, 2012. Web. 10 Oct. 2012. <http://www.futurlec.com/Ultrasonic_Sensors.shtml>. [1] Q-Spot™ 560-LED. Digital image. Chauvet Professional. Chauvet Lighting. Web. 1 Mar. 2012. <http://www.chauvetlighting.com/qspot560.html>.

[6]"Solo 250." Solo 250. N.p., n.d. Web. 14 Oct. 2012. <http://www.omnisistem.com/o/index.php/intelligent/solo-250>. [8] Sylla, Iboun T. "To ZigBee or Not to ZigBee? Factors to Consider When Selecting ZigBee Technology." EE Times Design. Texas Instruments, 13 Mar. 2009. Web. 12 Oct. 2012. <http://www.eetimes.com/design/microwave-rf-design/4019027/To-ZigBee-or-Not-to-ZigBee-Factors-to-consider-when-selecting-ZigBee-Technology>. [5] Ultrasound in Diagnostics and Therapy. N.p.: Http://www.anst.uu.se/hanslund/Med_Tekn/ultrasound.pdf, n.d. PDF. [2] Wi-Fi Location-Based Services 4.1 Design Guide. Publication no. OL-11612-01. Cisco Systems, Inc., 20 May 2008. Web. 10 Sept. 2012. <http://www.cisco.com/en/US/docs/solutions/Enterprise/Mobility/wifich1.html>.

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9. Appendices Part Number Description Data Sheet

MRF24J40MA-I/RM MODULE RF TXRX PICTAIL PLUS http://ww1.microchip.com/downloads/en/DeviceDoc/70329b.pdf

PIC18F25K20-I/SS IC PIC MCU FLASH 16KX16 28SSOP http://ww1.microchip.com/downloads/en/DeviceDoc/41303G.pdf

LM555CM 555 Type, Timer/Oscillator (Single) http://www.fairchildsemi.com/ds/LM/LM555.pdf

LT1615ES5#TRMPBF IC REG BOOST ADJ 0.35A TSOT23-5 http://cds.linear.com/docs/Datasheet/16151fas.pdf

TL331IDBVR IC DIFFCOMPRTR SINGLE SOT-23-5 http://www.ti.com/lit/ds/symlink/tl331.pdf

LM318M/NOPB IC OP AMP HIGH SLEW RATE 8-SOIC http://www.ti.com/lit/ds/symlink/lm118-n.pdf

MAX485CSA+ IC TXRX RS485/RS422 LOWPWR 8SOIC http://datasheets.maximintegrated.com/en/ds/MAX1487-MAX491.pdf

LM7805CT IC REG LDO 5V 1A TO-220 http://www.fairchildsemi.com/ds/LM/LM7805.pdf

LTC1474CS8-3.3#PBF IC REG BUCK 3.3V 0.75A 8SOIC http://cds.linear.com/docs/Datasheet/14745fas.pdf

DF1BZ-4P-2.5DSA CONN HEADER 4POS 2.5MM STR TIN http://www.hirose.co.jp/cataloge_hp/e54102006.pdf

709-PS25-12 Linear and Switching Power Supplies 25.2W 12V 2.1A http://www.meanwell.com/search/PS-25/default.htm

NC3FBAH1 XLR Connectors 3P FEMALE CHASS HORIZONTAL http://www.neutrik.us/NC3FBAH1

XC6SLX9-2TQG144C IC FPGA SPARTAN-6 9K 144TQFP http://www.xilinx.com/support/documentation/data_sheets/ds162.pdf

SMAJ6.0A DIODE TVS 6.0V 400W UNI 5% SMA

http://www.littelfuse.com/~/media/Files/Littelfuse/Technical%20Resources/Documents/Data%20Sheets/Littelfuse_TVS%20Diode_SMAJ.pdf

1N5236B-TR DIODE ZENER 7.5V 500MW DO35 http://www.vishay.com/docs/85588/1n5221b.pdf

LM5001SD/NOPB IC REG MULTI CONFIG ADJ 1A 8-LLP http://www.ti.com/lit/ds/symlink/lm5001.pdf

IRFL9110TRPBF MOSFET P-CH 100V 1.1A SOT223 http://www.vishay.com/docs/91196/sihfl911.pdf

MBR0530L-TP DIODE SCHOTTKY 0.5A 30V SOD-123 http://61.222.192.61/mccsemi/up_pdf/MBR0520L~MBR0540L%28SOD-123%29.pdf

BAT54-7-F DIODE SCHOTTKY 30V 200MW SOT23-3 http://www.diodes.com/datasheets/ds11005.pdf

IRFL110TRPBF MOSFET N-CH 100V 1.5A SOT223 http://www.vishay.com/docs/91192/sihfl110.pdf

2128 Category: 18500 Cell Holders http://www.batteryspace.com/batteryholder1xcwith624awgwireleads-rohscompliant.aspx

1N4148-TAP DIODE SWITCH SS 75V 300MA DO35 http://www.vishay.com/docs/81139/1n4148w-.pdf

FN9263S-3-06 AC Power Entry Modules 3A 250VAC 50/60Hz Snap-in vertical

http://www.schaffner.com/uploads/tx_w4products/DS_FN9263_web.pdf

US1640 Ultrasonic Transducer 40kHz http://www.futurlec.com/Ultrasonic_Sensors.shtml

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Appendix 1: MATLAB Code for Position Calculator

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