133972821-line-follower-robot-using-8051-micro-controller-doc.docx

133972821-line-follower-robot-using-8051-micro-controller-doc.docx

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Nov 6 How to make a line follower robot using 8051 micro controller - P89V51RD2 Introduction The line follower is a self operating robot that detects and follows a line that is drawn on the floor. The path consists of a black line on a white surface (or it may be reverse of that). The control system used must sense a line and maneuver the robot to stay on course, while constantly correcting the wrong moves using feedback mechanism, thus forming a simple yet effective closed loop System. The robot is designed to follow very tight curves Sample Paths The path is a black line on a white background with width of 3 cm (except at bends where a little variation may be present). It may contain paths laterally displaced by a around 3 cm and also gap of at most 5 cm. (All these specifications may vary one competition to other). . From above images we can conclude that in most of line follower competitions, we have to perform some additional task apart from following the line. Basic design and requirements The robot is built with P89V51RD2, L293D, IR sensors, LM324 , platform consisting of a toy car chassis (or hand made Al sheet chassis). The robot is designed using two motors controlling wheels. It has infrared sensors on the bottom for detect black tracking tape .It captures the line position with the help of these optical sensors called opto-couplers mounted at front end of the robot. (Each opto-coupler consists of an IR LED and an IR Sensor) when the sensors detect black surface, output of comparator, LM324 is low logic and for white surface the output is high. It reports to Figure 1: Basic Sample Arena Figure 2: Sample Arena of Kurukshetra’08 (Anna University) the microcontroller for accurate control and steering of motors. Microcontroller P89V51RD2 and Motor driver L293D were used to drive the motors. Basic operation The basic operations of the line follower are as follows: 1. Capture line position with optical sensors mounted at front end of the robot. For this a combination of IR LED’s and Photo Transistor called an optocoupler is used. The line sensing process requires high resolution and high robustness. 2. Steer robot to track the line with any steering mechanism. To achieve this we use two motors governing wheels motion. Block Diagram Let’s see all the system in detailed manner. INPUT SYSTEM
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Sensors IR reflective sensors have one emitter (IR LED) and one receiver (Phototransistor or photo diode. If we have white surface it reflects the light and it will sensed by the receiver, similarly if we have black surface it absorbs the light and receiver can not sense light. Photo diode has property that if IR light fall on it its electrical resistance comes down ( i.e. its comes down from 150kΩ to 10kΩ if no noise present).For sense the change in resistance we use voltage divider circuit (as shown in figure below).
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  • Winter '13
  • dsfcv
  • Voltage divider, DC MOTORS, PORTD

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