Elevator Door Control

7/28/2019 Elevator Door Control

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Contents1- Introduction: .............................................................................................................................................. 4

2-Objective:...................................................................................................................................................4

3-Theory:.......................................................................................................................................................

5

3.1Basic concept of Laser: ............................................................................................................................ 5

Spontaneous emission: .................................................................................................................................. 5

Stimulated emission ...................................................................................................................................... 54-Circuit Components: ....................................................................................................................................7

4.1 Op-amp LM-741: .................................................................................................................................... 8

4.2 PIC16F84A 18-pin Enhanced FLASH/EEPROM: ................................................................................. 9

4.3 L293 quadruple half-H driver: .............................................................................................................. 10

4.4 2N5777 Silicon NPN Photo Detector: .................................................................................................. 10

4.5 DC Motor: ............................................................................................................................................. 11

4.6 Laser Light(650nm-5mW laser Pointer): .............................................................................................. 11

4.7Table of components: ............................................................................................................................. 125 -Theory of operation: ................................................................................................................................. 13

6-Simulation: ............................................................................................................................................... 13

6.1 Schematic: ............................................................................................................................................. 137-Hardware Implementation:......................................................................................................................... 14

8-Problems: ................................................................................................................................................. 14

9-Conclusion:............................................................................................................................................... 14

10-List of references:....................................................................................................................................

15


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List of Tables:

Table 1: Some Op-amp Parameters.10

Table2: Transmitter components..13

Table3: Receiver components..13


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1- Introduction:

A laser is a device that emits light (electromagnetic radiation) through a process of optical

amplification based on the stimulated emission of photons. The term "laser" originated as

an acronym forLight Amplification by Stimulated Emission of Radiation. The emitted laserlight is notable for its high degree of spatial and temporal coherence, unattainable using

other technologies, unlike wires, also does not require special shielding, laser is used now in

our life in many applications like: telecommunication, military application, industrialapplication, and scientific researches.

2-Objective:

The objective of this circuit is to control elevator door opening and closing movement with

laser beam as light source, and Silicon NPN Photo Detector as light detector, the door close

as long as the laser beam is detected by the photo detector, when laser interrupted by anymovement that cut the laser beam elevator door open immediately.

Figure1: Dc-Motor control Block Diagram


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3-Theory:

There is only one way that light can be produced: that is, through the rapid change of state of

an electron from a state of relatively high energy to a (more stable) state of lower energy.

When this happens the energy has to go somewhere and it is often emitted in the form oflight. The word "laser" is an acronym for Light Amplification by Stimulated Emission of

Radiation. Lasers are finding ever increasing military applications principally for target

acquisition, fire control, and training. These lasers are termed rangefinders, target

designators, and direct-fire simulators. Lasers are also being used in communications, laserradars (LIDAR), landing systems, laser pointers, guidance systems, scanners, metal working,

photography, holography, and medicine.

The primary wavelengths of laser radiation for current military and commercial applications

include the ultraviolet, visible, and infrared regions of the spectrum. Ultraviolet radiation forlasers consists of wavelengths between 180 and 400 nm. The visible region consists of

radiation with wavelengths between 400 and 700 nm. This is the portion we call visiblelight. The infrared region of the spectrum consists of radiation with wavelengths between

700 nm and 1 mm.

3.1Basic concept of Laser:

Spontaneous emission:is really the normal case. When an electron is elevated to a high

energy state this state is usually unstable and the electron will spontaneously return to amore stable state very quickly (within a few picoseconds) emitting a photon as it does so.

When light is emitted spontaneously its direction and phase will be random but the

wavelength will be determined by the amount of energy that the emitting electron must give

up.

Stimulated emissionis what happens in the operation of a laser. In some situations whenan electron enters a high energy (excited) state it is able to stay there for a relatively long

time (a few microseconds) before it changes state spontaneously. When an electron is in this

semi-stable (metastable) high energy state it can be stimulated by the presence of a photonof light to emit its energy in the form of another photon. In this case the incident photon

must have the right energy (wavelength) within quite small limits.

It is of fundamental importance to understand that when stimulated emission takes place the

emitted photon has exactly the same wavelength, phase and direction as that of the photon

which stimulated it. For spontaneous or stimulated emission to occur, energy must be

supplied to boost the electron from its low energy state to a higher energy state.


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Figure 2: Energy state diagram showing: (a) absorption; (b) spontaneous emission;(c) Stimulated emission. The black dot indicates the state of the atom before and after a transition takes

place

The energy can come from many sources:

Heat.

Electrical Discharge.

Electric Current.

Chemical Reaction. Biological Reactions (Bioluminescense).

Absorption of Light.

Nuclear Radiation.

(a) By spontaneous emission in which the atom returns to the lower energy state in anentirely random manner;

(b) By stimulated emission when a photon having an energy equal to the energy difference

between the two states (E2 E1) interacts with the atom in the upper energy state causing it

to return to the lower state with the creation of a second photon.


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4-Circuit Components:

OP-AMP BASICS:

An operational amplifier is a very high gain amplifier having very high input impedance

(typically a few Mega ohms) and low output impedance (less than 100 ).

The basic circuit is made using a difference amplifier having two inputs (plus and minus)

and at least one output. the plus (+) input produces an output that is in phase with the signal

applied, while an input to the minus (-) input results in an opposite polarity output.

Feedback:

*There are two types of feedback

Negative feedback allows high-precision signal processing.

Positive feedback makes it possible to build oscillators

Some Op-amp Applications:

1- Non-Inverting Amplifier.

2- Inverting Amplifier.

3- Voltage follower (Buffer).

4-Voltage comparator

1-Voltage comparator:

Figure 3:

Figure 4: Voltage comparator


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Some Op-amp Parameters:

PARAMETER ABBV UNITS DEFINITION

Bandwidth BW MHz The upper frequency limitation or useful

frequency range

Slew rate SR V/s The rate of change in the output voltagewith respect to time

for a step change at the input.

4.1 Op-amp LM-741:

The LM741 series are general purpose operational amplifiers which feature improvedperformance over industry standards the lm741is reliable and required no frequency

compensation.

Above all, it was much easier to manufacture and had good yields.

Features:

Short-Circuit Protection.

Offset-Voltage Null Capability.

Large Common-Mode and Differential Voltage Ranges.

No Frequency Compensation Required.

Low Power Consumption.

No Latch-Up

Figure 5: LM-741

Table 1: Some Op-amp Parameters


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4.2 PIC16F84A 18-pin Enhanced FLASH/EEPROM:

Description:The PIC16F84A belongs to the mid-range family of the PICmicro microcontroller devices.

Features

13 I/O pins with individual direction control High current sink/source for direct LED drive

- 25 mA sink max. per pin

- 25 mA source max. per pin

TMR0: 8-bit timer/counter with 8-bit programmable prescaler

Special Microcontroller Features:

10,000 erase/write cycles Enhanced FLASH Program memory typical

10,000,000 typical erase/write cycles EEPROM Data memory typical

EEPROM Data Retention > 40 years In-Circuit Serial Programming (ICSP) via two pins

Power-on Reset (POR), Power-up Timer (PWRT), Oscillator Start-up Timer (OST)

Watchdog Timer (WDT) with its own On-Chip RC Oscillator for reliable operation

Code protection

Power saving SLEEP mode

Selectable oscillator options

CMOS Enhanced FLASH/EEPROM Technology:

Low power, high speed technology Fully static design

Wide operating voltage range:

- Commercial: 2.0V to 5.5V

- Industrial: 2.0V to 5.5V

Low power consumption:

- < 2 mA typical @ 5V, 4 MHz

- 15 mA typical @ 2V, 32 kHz

Figure6: PIC16F84A


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4.3L293 quadruple half-H driver:

The L293 is quadruple high-current half-H driver. The L293 is designed to provide

Bidirectional drive currents of up to 1 A at voltages from 4.5 V to 36 V.

The L293 is designed to drive inductive loads such as relays, solenoids, dc and bipolarstepping motors, as well as other high-current/high-voltage loads in positive-supply

applications.

Features:

Wide Supply-Voltage Range: 4.5 V to 36 V

Separate Input-Logic Supply

Internal ESD Protection

Thermal Shutdown

High-Noise-Immunity Inputs Output Current 1 A Per Channel (600 mA for L293D)

Peak Output Current 2 A Per Channel (1.2 A for L293D)

4.4 2N5777 Silicon NPN Photo Detector:

Features:

High sensitivity.

Economical TO-92 compatible.

Figure7: L293 quadruple half-H driver


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4.5 DC Motor:

Specifications:Rated voltage: 12VDC

No load speed: 3430 r/minNo load current: 0.17A

Rated torque: 102 gcm

Rated current (at maximum efficiency): 0.52A

Rated speed: 2640 r/min

Output power: 2.72 W

Stall Tourqe: 450 g.cm

Stall Current: 1.7A

4.6 Laser Light(650nm-5mW laser Pointer):

Laser light is very different from normal light. Laser light has the following properties:

The light released is monochromatic. It contains one specific wavelength of light (one

specific color). The wavelength of light is determined by the amount of energy

released when the electron drops to a lower orbit.

The light released is coherent. It is organized -- each photon moves in step with the

others. This means that all of the photons have wave fronts that launch in unison.

The light is very directional. A laser light has a very tight beam and is very strong and

concentrated. A flashlight, on the other hand, releases light in many directions, and the

light is very weak and diffuse.

Figure8: Dc-motor


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4.7Table of components:

1-Transmitter:

2-Receiver:

part value quantity

Laser torch _ 1

part value quantity

Resistor 10 k 1

Resistor 1 k 3

Capacitor 22 PF 2

Crystal 4Mhz _ 1

Pic 16f84a _ 1

2N5777 (photo transistor) _ 1

L293 quadruple half-H driver _ 1LM-741 _ 1

Dc-Motor _ 1

Table2: Transmitter components

Table3: Receiver components


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5 -Theory of operation:

The Circuit has two sections: the transmitter element and the receiver board, both powered

by a fixed voltage power supply. The transmitter is the laser diode has an inbuilt collimating

lens. The receiver uses a photodiode as the receiving element. The phototransistor of thereceiver must be accurately oriented towards the laser beam from the torch.

That makes the motor rotate in certain direction, If there is any obstruction in the path of thelaser beam, The motor will rotate in the opposite direction.

And this rotation simulate the elevator door closing when the laser is connected to the photo

transistor and opening when the laser interrupted by anything (i.e. moving person try to enter

the elevator).

6-Simulation:

By making the circuit in proteus circuit simulator.

6.1 Schematic:

Figure9: circuit schematic


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7-Hardware Implementation:By connecting the circuit as shown in figures.

8-Problems:

1- Low quality components.

2- Visible laser source (850nm).3- Low performance photo-Diode.

9-Conclusion:

The project shows that its possible to make elevator door control using laser by simple andinexpensive components, and with accepted accurecy by controling the closing and opening

conditions with the 16f84a pic.

Figure10: Hardware implementation


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10-List of references:

1- Optical Fiber Communications Principles and Practice Third edition John M. Senior.

2- Understanding Optical CommunicationsHarry J. R. Dutton

3-PIC16F84A Data sheet.

4- L293 quadruple half-H driver Data sheet.

5- lm-741 Data sheet by Fairchild.

Date post:	03-Apr-2018
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Elevator Door Control

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