06-04-2015, 05:30 AM
viva questions on rf controlled fire fighting robort
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line follower robot using p89v51rd2 microcontroller
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viva questions on rf controlled fire fighting robort
23-03-2017, 12:41 PM
Robot of line follower with 8051
Line follower robots were one of the first automatic guided robots. They can follow a marked line on a contrasting background, usually a black line on a white surface or a white line on a black surface. In general, the line follower robot works on a closed loop feedback algorithm in which the line sensor feedback is used by the controller to correct the robot path. The sensors are usually LED / LDR, LED / photodiode or pairs of LED / phototransistor and the controller is an electronic circuit that executes the desired feedback algorithm. Gear motors are used to power the robotic wheels.
Note: - If you are interested in Arduino-based development, we have created this same robot line follower with Arduino as well. You can test the Arduino based circuit too to see how the same project is developed using different controllers.
The line follower robot presented here is designed to follow a black line on a white background. It has a pair of sensors (LED / LDR) and works on a simple "align robot in the center of the line algorithm". Actually you do not need a microcontroller to implement such a simple robot. A set of comparators and a motor controller circuit happily do the job. But I'm using the microcontroller just to demonstrate the technology. This project also serves as a platform for advanced online follower robots working on complex algorithms. Atmel AT89S52 is the microcontroller used here.
Sensor
The sensor part consists of a set of LED / LDR pairs for left and right sides. These LED / LDR pairs detect the black line on the white surface on which the robot is supposed to move. The LDR has an inverse relationship between its resistance and the light that falls on it. When a particular LED / LDR pair is above the white surface, the reflected light falls on the LDR and its resistance falls, whereas when the LED / LDR pair is above the black line, its resistance increases. This variation in the resistance of the LDRs is used to evaluate the orientation of the robot line follower in the X-Y plane. The figure below shows the sensor circuit.
![[Image: light-sensor-circuit.png]](http://www.circuitstoday.com/wp-content/uploads/2013/12/light-sensor-circuit.png)
In the circuit, the resistors R1 and R2 limit the current through the lighting LEDs D1 and D2. The resistors R3, R5 and R6, R8 form a voltage divider together with the corresponding LDRs.
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