Multidisciplinary Senior Design Conference Kate Gleason College of Engineering

Rochester Institute of Technology Rochester, New York 14623

Project Number: P13331

   

Active Parking Management  

Wynn Aung Conley Brodziak Electrical Engineering Mechanical Engineering

Andrew Eggers Tyler Ludwig

Computer Engineering Mechanical Engineering  Abstract

During high volume traffic periods, it can be difficult for commuters to locate a parking location that is convenient in terms of both distance to the campus in general, and to their desired building in particular. The purpose of this project is to mitigate this difficulty by designing a system that informs commuters of the real-time parking availability in a given lot. The decided system architecture performs on the basis of counting the net inflow and outflow of cars into a given lot and uses this data, in conjunction with the total lot capacity, to inform commuters of the general lot status, and give a numerical representation of available spaces in that lot. The system employs a tactile pressure sensor, providing some of the most reliable results when attempting to count vehicular traffic. This pressure system utilizes what is known in the car-counting industry as “road tube” which provides a pressure pulse to the accompanying sensor when a car tire rolls over the tube. The rest of the system was designed around this central operation, including the programming logic, a lot status indicator, the power budget, user interface, and mechanical structure.

Introduction

The objective of this project was to design a system that would assist commuters at RIT with the oftentimes laborious and fuel-wasting task of locating a parking lot that best suits their general on-campus destination and optimizes the time they will spend looking for the closest spot in that lot. This project focused on implementing a pilot system to deliver real-time parking availability in one lot at RIT. As many RIT commuters are aware, the parking on campus is segregated between general and reserved parking spaces in most lots. In addition, almost all lots on campus contain multiple entrances. To reduce these complexities, lot N was chosen as the lot in which to implement the system as it offered a single entrance and contained no reserved parking sections.  Design Process Customer Needs, Specifications & Function Decomposition In the genesis of the project, an initial meeting with the customer defined the boundaries of the project by way of certain needs and desired system specifications. Figure 1 details the customer needs that were identified for this project. Each customer need was weighted for importance on a three-tiered scale (1,3, or 9). To accompany these needs, various specifications were generated to bound the solution and quantify the specific parameters that would satisfy the customer needs within the scope of the design project. The final set of specifications can be seen in Figure 2. From the determined customer needs and specifications, the team reduced the system to a functional decomposition to aid in the concept selection process. The diagram containing this breakdown can be seen below in Figure 3

 

 Figure 1: Customer Needs  

 

 Figure 2: Specifications

                               

Figure 3: Functional Decomposition

Initial Concepts & Selection

Starting with customer needs, the team brainstormed a number of solutions ranging from hiring a co-op student to stand out in the entrance of the parking lot with a hand operated tally counter, to using infrared cameras to detect a car as a heat source. Taking customer specifications and complexity into account, the majority of these ideas were discarded. Some of the most constricting specifications were budget, sensor implementation, and minimal alteration to the parking lot infrastructure.

An initial customer need indicated that the designed system could not employ any in-road sensing technology. Thus, initial concepts all revolved around a system that existed solely as a unit alongside the entryway. It was determined that a standard pole would suit the design task. The team was able to secure a used pole from a previous Senior Design project that had been taken down due to construction. In addition to the pole, a 400W wind turbine and two deep cell batteries were also donated, which is discussed later the system power section. These acquisitions reduced total costs significantly.

The Federal Highway Administration [1] was a great resource for deciding which sensor system best fit our needs. Some sensor technologies such as inductive coils and piezoelectric strips were quickly ruled out due to cost. Magnetometers and image detection were two sensor technologies that fit the budget requirements and allowed for off-road detection. Image detection was deemed to be too reliant on software, considering the skill set of the team. The team decided to pursue a magnetometer solution. After some initial trial testing, it was determined that a magnetometer solution was not feasible given the required system accuracy and the detection distance needed. A second concept was pitched to the customer as an option, despite not meeting the specification of not damaging the parking lot; this idea was to use tactile road tube with pressure sensors. To secure the road tube to the pavement, some sort of drilling or re-paving would have to occur. The customer approved of the use of road tube because of its reliability, and the limited impact that it would have on the pavement. To mitigate the risk of the sensors being damaged during winter plowing, it was suggested by facilities that we add a speed bump to the lot entry and install the sensors on the speed bump. This would require any plows to raise their plow when removing snow.  Overall System

The final design consists of “city tube” (two road tubes with a rubber interconnect for easy installment) secured to either side of a plastic speed bump that spans the entrance of the lot coupled with air pressure sensors (air switches) buried in an irrigation box in the ground on the side of the lot entry. The main structural system consists of a 14’ vertical aluminum pole and a control/user interface box. On this pole is mounted a seven segment display and 360 degree general lot status indicator for communicating the parking status. In addition, a 60W solar panel and the donated 400W turbine were placed on the pole as the source of the system’s power. In the control box, two deep cell batteries provide the storage capacity for the power generation system. The control box also contains the system’s microcontroller, circuitry, and user input devices. General Indicator & Seven Segment Display Electrical The indication system contains two parts, the main indicator consisting of an array of red/green lights to indicate the general lot status and a seven segment display to show a numeric representation of available spots. The purpose of the general indicator system is to inform commuters of the availability of spaces in the lot. Its function is to light up green LEDs when there is, at minimum, one free spot in the lot (the lot is open) and to switch to red LEDs when there are no free spots left (the lot is closed). The design of the main indicator was performed in two parts: selecting suitable LEDs and designing a circuit diagram to implement the system. The system utilizes tape-strip LEDs. On each strip of LEDs, three LEDs are connected in series with integrated current limiting resistors. Each section of three LEDs are supplied with 12V DC and the sets are tied together in parallel across power rails. Each set draws 20mA and therefore the strip draws 1.2A in total. Due to the decision to flash the LEDs as discussed in the next section, this current draw was reduced to 600mA.

 

It was decided that the general indicator should flash at a rate of 1Hz to increase the overall visibility, especially in direct sunlight. To facilitate this, a circuit was designed to implement this blinking functionality. The final design is shown below in Figure 4

Figure 4: Indicator Blinking Circuitry

In the designed circuit, a 555 timer chip provides clock signal for blinking. Resistor and capacitor

values were calculated and set to provide frequency of 1Hz. An AND gate provides voltage “cleanup”, taking 555 output swing from 0.21V to 4.8V. A solid-state relay (SSR) provides power switching capabilities for LED arrays. Enable signal (EN) from the Arduino is connected to pin 4 of the timer and controls the reset functionality of 555 timer. Setting EN = 0 will lead SSR to open-circuit situation and thereby turning off the whole circuit. On the contrary, the circuit will be ON as long as EN signal is high. Electromechanical relay performs the selection of color, based on the signal from Arduino. To maximize the lifetime of electromechanical relay, it is designed to be switched when there is no current flowing through the relay. Green LEDs will light up as long as color selection signal (CS) is zero. When the number of cars counted by the microcontroller equals to the number of spots in the parking lot, Arduino will set CS signal high which would cause the electromechanical relay to switch the output to red LEDs.

After the circuit was built and tested on the breadboard, a PCB layout was then designed. In this second

step, the software named ExpressSCH and ExpressPCB were used. The schematic of the circuit was first drawn in ExpressSCH and the layout was drawn in ExpressPCB by linking with the schematic. The final PCB is shown below in Figure 5.  

 Figure 5: Printed Circuit Board, Upper Layer (Left) & Lower Layer (Right)

The LED indicator meets with the two important customer needs that are concerned with indication system,

such as informing commuter of lot status and being visible above landscape. The indicator runs well and the flashing light is visible from 150 yards under sunlight at noon. As further improvement, the frequency of the blinking light can be adjusted by changing the values of resistor if a different frequency is desired.   The seven segment displays that were chosen are 6” tall and operate on 12V DC. Three digits were used because the lot capacity is not expected to ever exceed 999. Three shift registers with tri-state buffers were used to selectively sink current to ground through the open collector outputs. 300 Ω resistors were used to limit the current

of each segment in the display. Three lines from the microcontroller unit were used to control the shifters: data in, data shift clock, and output buffer clock.  Mechanical

To house the general indicator, a housing of black ABS plastic was constructed with a footprint of 2’x2’.

The indicator housing contains a square through hole in the center that allows for the unit to mount to the pole. To create a 360 degree viewing angle, the section housing the LEDs is circular with a diameter of 18” and is shielded via a sheet of clear lexan. The LED’s and power connections inside the unit were designed such that all components are housed in a weatherproof section. The unit is mounted to the pole via tensioned bolt connections that “hug” the pole.

The seven segment housing was designed out of aluminum u-channel and also contained a clear lexan viewing window. The housing dimensions are 16”x10” and was designed to enclose the seven segment electronics and then sealed via a steel backplate and silicone sealant. This housing was mounted to the pole in a similar fashion as the indicator, via a tensioned bolt connection. Power System

As one of the customer needs stated that the system be powered off grid, autonomous power generation was pursued. Based on the decided indication systems (LED array and seven segment display) and the power needs of the various other components, an initial estimated power budget was created. This power budget can be seen below in Figure 6.

Figure 6: Power Budget

Initially, a solar array was decided as the main source of power. Due to system budget, it was realized that a sufficient array was not within budget, so alternatives were investigated. As mentioned earlier, the team received a 400W wind turbine and two deep cycle batteries from RIT Facilities. To provide a robust design that was capable of operating indefinitely regardless of the weather conditions, both power generation technologies were implemented. The overall power system consisted of these two power generation technologies coupled with an array of 12V 55Ah deep cycle batteries. The turbine and solar cells provides a trickle charge to the battery array while the system runs from the batteries. The tandem power design assured that the required power would be available to trickle charge the battery array and allow for continuous system operation regardless of the weather conditions.

Several of system components required the 12V supply of the battery array to be stepped down and/or regulated. The Arduino requires an 8V DC input, the user display and air switches required 5V DC, and the LED array and seven segment displays required a regulated 12V DC supply. For simplicity, linear regulators were used to facilitate these needs. The overall power system schematic displays all top-level connections in the system. This diagram is shown below in Figure 7.

Figure 7: Overall Power Schematic

Control Box

A user control surface inside the box contains several components for system operation. An ammeter provides the current being delivered via the solar array and the turbine. There are three switches that allow the user to disconnect the solar array and/or the turbine as well as an overall system power switch. Finally, a small display, numeric keypad, and SD card reader comprise the system logic and data control. An Arduino Atmega 2560 was decided on to control the displays and read sensor interrupts. To help the school better understand tracking patterns, it was decided that a real time clock would be used to keep time, and timestamps would be used to save parking data to an SD card for use by the parking administration. Microcontroller & Count Algorithm The pressure sensors connected to the road tubes were powered by 5V, and the outputs were pulled up to 5V with 10K resistors. The outputs were connected to the Atmega2560’s external interrupt pins. Interrupts were setup to be triggered on the falling edge, and separate subroutines were written for each sensor. Each of the ISR’s functioned similarly, updating the current time from the real time clock and adding the time to a running list of sensor hits. In the main loop, another function is called to throw out repeat sensor hits, group sensor hits by vehicle, decide whether the car is entering or leaving, and save the data to the SD card. The SD card adapter and Real Time Clock both use SPI to communicate with the microcontroller. Pole Structure & Design

A 14’ aluminum pole comprised the central mechanical structure for the system. This pole was mounted to a concrete base, which was donated by RIT facilities. Five major components were mounted to this pole: from top to bottom the pole contained a wind turbine, general indicator, solar panel, seven segment display, and control box. Each of these components (except the turbine, which is discussed next) were clamped to the pole with 8” long hex bolts. Due to the excessive amount of weight being added to the pole, a finite element analysis was performed to ensure that the pole would remain erect during extreme conditions, namely wind gusts of 70mph. The final results indicated that the pole would flex a great deal, but without failure. Turbine Mounting & Ground Rod

The turbine is mounted at the very top of the pole via a custom designed mount. This mount existed from a previous senior design project and has been field-tested. As a redundant safety measure, a tether was routed from the turbine through the pole and secured at the base. The tether for the turbine was bolted near the base of the pole to prevent detachment of the turbine in extremely strong wind conditions.

A ground rod is needed to route any excess charge created from the turbine from destroying the system. It

is located inside the irrigation box and wired through the pipe leading up into the pole and to the turbine . Solar Bracket Many crosswalk lights around the RIT campus are already powered with a solar panel and battery combination, so a quick glance at one gave the team a proven solution on how to mount the solar panel. In the final design two steel L-channels were bolted directly to the back of the solar panel. On the opposing legs of each L-channel were bolted two different lengths of strut channel, to form a 43 degree angle from horizontal which maximizes exposure to sunlight as Rochester lies at 43 degree Longitude. The similar lengths of strut channel were connected with another piece of strut channel, L-brackets, and bolts which were subsequently clamped to the pole with shorter strut channel and 8” long hex bolts. General System Installation

The concrete base was delivered to N lot and installed in the ground. On 1 May 2013 the majority of the project was erected in N lot. Time was spent moving the project outside from the 4th floor of the engineering building, attaching the solar panel and user interface/control box, routing wires, making electrical connections, touching up the paint, mounting the pole on the pre-installed concrete base, and debugging the system.

Speed Bump & Road Tube Installation The speed bump was installed by Facilities, and shortly thereafter the team installed the road tube as planned. Threaded inserts were hammered into the speed bump in approximately 8” intervals, and the city tube was secured using fender washers and 10-24 by ½” screws; as discussed later, this was not the final solution.

The road tube was routed underground to the pressure sensors in a manner that was not designed. The team

had decided not to cement together the pvc tube routing system until the composition of the ground was understood and a hole was dug. When the team started digging up the ground to install the routing system, it found many rocks and a deep layer of asphalt that prevented digging more than 6” deep. After some deliberation the team resolved to simplify the final design and eliminate the complexity and bulkiness by not having the underground road tube isolated from the elements. A drainage system was improvised to disallow water from entering the LB box which houses the sensors and electrical wires in the irrigation box.

An oversight when securing the city tube to the speed bump necessitated an overhaul in the design as mentioned earlier. Due to the composition of the speed bump (a very waxy plastic), and the cool temperatures during the time the threaded inserts were hammered in, when the temperature became warmer the holes for the inserts expanded allowing them to creep out. Also overlooked was the expansion of the city tube under hot conditions causing ripples along the speed bump. Additionally the team discovered that if the drive wheels of a vehicle stop exactly on the leading edge of the speed bump and the vehicle accelerates, the wheels will spin and disassemble the city tube, screws, washers, and inserts in a destructive manner. To rectify the downfalls of the initial speed bump design, the team tested a few other methods before converging on the final design. Helicoils of ¼” by 1” size were tested in a scrap piece of speed bump and a screw was threaded in, but pliers and a small amount of force easily uncoiled and pulled the Helicoil out of the speed bump. It should be noted here that the purpose for trying threaded inserts and Helicoils first was to allow replacement of the city tube as it is estimated to last only 6-8 months [2] without destroying the speed bump with new screw holes every time the tube is replaced. Because this ease of replacement was not a customer need or specification, but rather a convenience in the design, ⅜” by 1.5” lag screws with large threads were ultimately used with two washers to undoubtedly secure the city tube to the speed bump. During the screw down process, on a hot day with the city tube expanded, one team member stretched the tube about ½” past taut at each screw interval to prevent further expansion and rippling. The excess tube was cut square to the speed bump and plugs were inserted into the end of the tube prevent water and sediment from entering, and to allow the pressure sensor to receive a pulse when a vehicle drives over. Budget

A total working system cost of $1391.66, even with all of the donated parts, was totaled and proposed as the lowest cost option that would meet all of the customer specifications. After some deliberation with the senior design budget office and the customer, a final budget of 1750 dollars was approved.

Team Dynamics

In the eleventh week of the project, one team member fell ill and had to take a medical leave of absence; this necessitated a redistribution of the power budget workload and a discussion analysis of whether or not the scope of the project was still realistic. Both the customer and MSD director agreed that scaling back the project was an option at this point, considering the circumstances. But the team decided to continue with the building the project as designed, partially because all parts were already ordered, and primarily because the majority of subsystems were required for operation of the system (ex: solar panel needed for power). It was determined that the project could still be completed as designed

Conclusions and Recommendations

All elements of the system design were installed and function independently, but integration of these systems is incomplete. The speed bump and road tube were successfully installed and have been tested for durability. In addition, it has been verified that the microprocessor receives road tube sensor data. Since the system design is predicated on the ability to count cars and use this data to communicate the lot status, many subsystems are adversely affected. The general indicator is capable of flashing green/red to indicate the lot status, but the lack of an operational counting algorithm provides no autonomous operation and is not able to convey any useful lot data. Similarly, the seven segment display was intended to provide a numerical representation of available spaces, but without data from the microprocessor this piece of hardware is irrelevant. In addition, some complications existed with the seven segment electronic design that impaired communication with the microcontroller. Elements inside the control box, due to time, were never implemented. The user display, numeric keypad, and SD card reader are existent but non-functioning. As a result, the logic for storing parking data was never developed.

The power generation systems have been tested and are capable of maintaining a full charge on the battery

array and thus the system can operate indefinitely without power intervention. The panel switches controlling the power functions also operate as expected.

All structural design elements were completed and provide skeleton infrastructure for the continued

development of this system. The team reserves with confidence that the shortcomings of this prototype will be mitigated by a future design team.  Acknowledgments

The team gives much thanks to all individuals that subsidized the success of this project with funds, donations, and/or words of encouragement including: Randy Vercauteren - Customer, and Director of Parking, Transportation, and Building Services; Enid Cardinal - Customer, and Senior Sustainability Advisor to the President (RIT); Les Moore – MSD Guide; RIT MSD Office, and it’s friendly staff; Facilities Management Services; Adam Petzold - Operations and Special Events Parking Manager; and Dave Harris - Dir Training/Utilities/Environ Mgmt RIT FMS.

Of equal value to the team is the time and dedication of those that helped with physical labor and problem solving including: Bruce Teuscher - Utilities Maintenance Technician; Chris Furnare - Grounds Foreman, and his crew; Colin Gibson - Technical support at Diamond Traffic Products; Beth Ritz - Sales at Diamond Traffic Products; Fred Gerding - High Leah Electronics, Inc. (dba Diamond Traffic Products); Dr. Becker - RIT Computer Engineering; and fellow students who gave advice or lent tools.

Everyone mentioned above was a integral part of this great team and the project would not have been a

success without you. Thank you. The RIT community in general has also been very supportive of the team through asking so many questions about the project as they saw us working diligently. The team thanks you all for your interest, and hopes that future design teams will continue to build on this project’s stalwart foundation.  References [1] FHWA: A Summary of Vehicle Detection and Surveillance Technologies used in Intelligent Transportation

Systems. http://www.fhwa.dot.gov/policyinformation/pubs/vdstits2007/index.cfm [2] Gibson, Colin B. "Road Tube Air Switch." Message to the author. 31 Jan. 2013. E-mail.

Colin B. Gibson is a representative of Diamond Traffic Products, the manufacturer of the road tube and air switches used in the project.