INTRODUCTION Robotics is an interesting subject to discuss about and in this advanced world, Robots are becoming a part of our life. As strange as it might seem, there is no standard definition for a robot. However, there are some essential characteristics that a robot must have and this might help one to decide what is and what not a robot is. It will also help us to decide what features are required to build into a machine before it can behave like a robot. A robot has the essential characteristics:1. Sensing : The robot should be able to sense its surroundings. Providing the robot with the sensors such as light sensors (eyes), touch and pressure sensors (hands), chemical sensors (nose), hearing and sonar sensors (ears), and taste sensors (tongue) will give the robot awareness of its environment.2. Movement : The robot needs to be able to move around its environment. Whether rolling on wheels, walking on legs or propelling by thrusters a robot should be able to move.3. Energy : The robot needs to be able to power itself. A robot might be solar powered, electrically powered, battery powered.4. Intelligence : A robot needs some kind of "smarts." A programmer is the person who gives the robot its smarts. The robot will have to have some way to receive the program so that it knows what it is to do.
So what is a robot? It is a system that contains sensors, control systems, manipulators, power supplies and software all working together to perform a task. Designing, building, programming and testing a robots is a combination of physics, mechanical engineering, electrical engineering, structural engineering, mathematics and computing. In some cases biology, medicine, chemistry might also be involved. A study of robotics means that it is an active involvement in all of these disciplines in a deeply problem-posing problem-solving environment. What is a line follower? Line follower is a machine that can follow a path. The path can be visible like a black line on a white surface (or vice-versa) or it can be invisible like a magnetic field. What is the need to build a line follower? Sensing a line and maneuvering the robot to stay on course, while constantly correcting wrong moves using feedback mechanism forms a simple yet effective closed loop system. The programmer gets the opportunity to ‘teach’ the robot how to follow the line thus giving it a human-like property of responding to stimuli.
MICROCONTROLLER(A T89S52) It has 40 pins and it is in dual in package It has 4 ports, 6 interrupts and 2 timers It has RAM of 128bytes and ROM of 4KB It is used for interfacing of the input and output modules
FEATURES Compatible with MCS-51® Products 8K Bytes of In-System Programmable (ISP) Flash Memory – Endurance: 1000 Write/Erase Cycles 4.0V to 5.5V Operating Range Fully Static Operation: 0 Hz to 33 MHz Three-level Program Memory Lock 256 x 8-bit Internal RAM 32 Programmable I/O Lines Three 16-bit Timer/Counters Eight Interrupt Sources Full Duplex UART Serial Channel Low-power Idle and Power-down Modes Interrupt Recovery from Power-down Mode
WORKING PRINCIPLE The Embedded Line following robot uses two motors to control rear wheels and the single front wheel is free. It has 3-infrared sensors on the bottom for detection of black tracking tape. When the middle sensor detects the black color, this sensor output is given to the comparator LM324. The output of comparator compares this sensor output with a reference voltage and gives an output. The output of comparator will be low when it receives an input from the sensor. A simple logic has been used to implement this project. As it is known that black colour is capable of absorbing the radiation and white colour or a bright colour reflects the radiation back. Here, 3 pairs of IR TX and Rx are used. The robot uses these IR sensors to sense the line and the arrangement is made such that sensors face the ground. The output from the sensors is an analog signal which depends on the amount of light reflected back and this analog signal is given to the comparator to produce 0s and 1s. Internally we have an OTP (one time programmable) processor which is used to control the rotation of the wheels. The rotation of these wheels depends up on the response from the comparator. Let us assume that when a sensor is on the black line it reads 0 and when it is on the bright surface it reads 1. Here we can get three different cases, they are:1. Straight direction2. Right curve3. Left curve
Straight direction: It can be assumed that the robot moves in straight direction when the middle sensors response is low and the remaining two sensors response is high. i.e., according to our arrangement the middle sensor will always be on the line and as the line is black in colour it will not reflect the emitted radiation back and the response of the sensor will be low and the response of the remaining two sensors will be high as they will be on the bright surface. Right curve: When a right curve is found on the line the responses will change i.e. the response of the first sensor which is to the right will become low as that sensor will be facing the black line and the remaining sensors response will be high. When this data is achieved, the control of the wheels is changed i.e. the right wheel is held constant and the left wheel is made to move freely until the response from the middle sensor becomes low. Then the same process repeats again. Left curve: When a left curve is found on the line the response of the left most sensor will be changed from high to low as the sensor will now face the black or the dark surface. Then the control of the wheel changes i.e. by holding the left wheel constant and allowing the right wheel to move freely until the middle sensor changes its response from high to low. The same process continues for all the turns and the robot moves continuously until the supply is removed.
Steps to follow the line (using single sensor): -Start. -Check for line. -Line detected go right. -Check for line. -If no line turn left till line detected. The arrangement of the sensors is shown in the figure.
LM 324 Wide gain bandwidth . : 1.3MHZ input common- mode voltage range Includes ground .largevoltage gain : 100DB .very lowsupply current/ampli : 375MA .low input bias current : 20NA low input offset voltage : 5mv max. Low input offset current : 2NA wide power supply range : Single supply : +3v to +30v Dual supplies : ±1.5v to ±15v
IR sectionWHAT IS INFRARED?Infrared is a energy radiation with a frequencybelow our eyes sensitivity, so we cannot see itEven that we can not "see" sound frequencies,we know that it exist, we can listen them.Even that we can not see or hear infrared, wecan feel it at our skin temperature sensors.When you approach your hand to fire or warmelement, you will "feel" the heat, but you cantsee it. You can see the fire because it emitsother types of radiation, visible to your eyes, butit also emits lots of infrared that you can onlyfeel in your skin
IR Transmitter, Receiver IR TRANSMITTER The IR LED emitting infrared light is put on in the transmitting unit. To generate IR signal, 555 IC based astable multivibrator is used. Infrared LED is driven through transistor BC 548. IR RECEIVER The TSOP17.. – Series are miniaturized receivers for infrared remote control systems. PIN diode and preamplifier are assembled on lead frame, the epoxy package is designed as IR filter
IR Emitter and IR phototransistor: An infrared emitter is an LED made from gallium arsenide, which emits near-infrared energy at about 880nm. The infrared phototransistor acts as a transistor with the base voltage determined by the amount of light hitting the transistor. Hence it acts as a variable current source. Greater amount of IR light cause greater currents to flow through the collector-emitter leads.
IR SensorFeatures:• Extra high radiant power and radiantintensity• High reliability• Low forward voltage• Suitable for high pulse currentoperation• Standard T-1¾ (∅ 5 mm) package• Angle of half intensity ϕ = ± 17°• Peak wavelength λp = 940 nm• Good spectral matching to Siphotodetectors
Lead Acid BatterySpecifications12V 1.3Ah sealed lead acid battery 1. CE and RoHs 2. high quality and relaibility 3. miantenance free 4. long life cycle12V 1.3Ah sealed lead acid battery General Features:Sealed and maintenance free operation.Non-Spillable construction design.ABS containers and covers(UL94HB, UL94-0)optional.Safety valve installation for explosion proof.High quality and high reliability.Exceptional deep discharge recoveryperformance.Low self discharge characteristic.Flexibility design for multiple install positions.
H-BridgeFeatures: 600 mA Output Current Capability Per Driver Pulsed Current 1.2 A / Driver Wide Supply Voltage Range: 4.5 V to 36 V Separate Input-Logic Supply NE Package Designed for Heat Sinking Thermal Shutdown & Internal ESD Protection High-Noise-Immunity Inputs
DC Geared MotorTechnical Specifications:•60RPM 12V DC motors with Metal Gearbox•6mm shaft diameter•Gearbox diameter 37 mm.•Motor Diameter 28.5 mm•Length 63 mm without shaft•Shaft length 15mm•300gm weight•38kgcm torque•No-load current = 800 mA(Max), Load current = upto 9.5A(Max)
ADVANTAGES Robot movement is automatic. Fit and Forget system. Used for long distance applications. Defense applications. Used in home, industrial automation. Cost effective.
APPLICATIONS Automated cars running on roads with embedded magnets. Guidance system for industrial robots moving on shop floor etc. Guidance system for industrial robots moving on shop floor etc. Industrial applications Home applications
CONCLUSIONIn this project we have studied and implemented aLine Following Robot using a Microcontroller forblind people. The programming and interfacing ofmicrocontroller has been mastered during theimplementation. This device is designed to providewith a greater advantage.
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