Analog Wall Following Robot

This is a group project done under the module EN2091 - Laboratory Practice and Projects, Semester 3, Department of Electronic and Telecommunication Engineering, University of Moratuwa.

Introduction

• Wall following robot is a robot that follows a wall and travels keeping a constant distance from the wall.
• Wall following is a common task in many robotics competitions.
• But the interesting point is our project was to build a robot that travels on the centerline between two walls using only analog electronics.
• That means we couldn’t use microcontrollers according to the guidelines.

Working Concept

• Two sharp IR sensors measure the distance from the robot to the side walls.
• The difference between the sharp IR sensor values is taken as the error signal and fed into a PID control circuit.
• The PID output signal is fed to the adder and subtractor circuits.
• The PID output and a comparator circuit generate two PWM signals with varying duty cycles.
• Then using the motor driver, PWM signals are fed to the left and right wheels.
• The robot tracks the walls and travels on the centerline between walls.
• Additionally we added another sharp IR sensor to the front of the robot to control the speed of the robot.
• The measured distance is compared with a predefined distance and the difference is taken as the error signal.
• The error signal is fed to a PID control circuit.
• A PWM signal is generated using the PID output and a comparator circuit.
• This PWM signal acts as the Base speed of the robot.
• Consequently the additional sharp IR sensor will vary the car's speed accordingly.

Sub Circuits and Tasks

• Instrumentation Amplifier- Reduce noise in Sharp IR sensor outputs and amplify signals
• PID circuit- Control the error signal smoothly using feedback
• Adder & Subtractor- Generate two PWM signals with varying duty cycles according to PID output
  • Motor 1= base speed + PID output
  • Motor 2= base speed - PID output
• PWM circuit- Generate two different comparator voltages for the two motors
  • Motor 1 duty cycle ∝ base speed + PID output
  • Motor 2 duty cycle ∝ base speed - PID output
• Voltage Regulator- To get 3.3V and 5V for required parts accordingly
• Speed Selector- Manually control the base speed

Hardware Specifications

• TL084CN ICs
• Two Sharp IR Sensors
• Two N20 Motors
• L298N Motor Driver
• Wheels
• Surface Mount Resistors
• Surface Mount Capacitors
• Other Components

Software Specifications

• Solid Works
• Altium Designer
• Multisim

Enclosure Design

PCB Design

PCB

Team Members

License

• This project is licensed under the MIT License. See the LICENSE file for details.

For More Information - Project Report