Edge Avoider Robot


Edge Avoider Robot (EAR) is a mobile device, which senses and avoids the absence of surface below it. This simple concept was designed by our RB researchers in order to help your robot to protect from falling. As like our previous robotic projects, this robot is also made without microcontroller to make everyone more comfortable on developing their own robot.

Components Required:

Edge Avoider Robot requires only simple mechanical and electronic components such as:

  • Robot Chassis – 1 no.
  • 12V DC motor (60 RPM) – 2 nos.
  • Plastic Wheels – 2 or 4 nos. (Based on the chassis)
  • Breadboard – 1 no.
  • IR Sensor module – 1 no.
  • IC 7805 – 1 no.
  • IC NE555 – 1 no.
  • IC L293D – 1 no.
  • 10 µF capacitor – 2 nos.
  • 0.1 µF capacitor – 1 no.
  • 9V Battery – 1 no. (requires according to the usage)
  • Battery Holder – 1 no.
  • Battery Snap – 1 no.
  • Breadboard Wires – 2 meters
  • LED – 1 no.
  • 1K & 10K Resistors – Each 1 no.
  • 10K Trim Pot – 1 no

Note: We recommend you to buy spare IC’s for all the IC specified in the component list. This could sometime help you to save your precious time if one IC fails to operate.

Circuit Diagram:

Connection Algorithm:

1)      Power Supply:

  • Take the breadboard and connect the battery holder in horizontal position.
  • Insert the positive and negative wire of battery snap in holder.
  • Attach IC 7805 (Voltage Regulator), and place one 10 µF capacitor in IN and GND connection of IC 7805 and other in GND and OUT connection.
  • Take the positive supply from the battery holder via breadboard wire and place it in IN of IC 7805, and also connect its negative supply in the last row of the breadboard.
  • Place the GND of IC 7805 in the last row of the breadboard, and transfer its OUT to the first row of the breadboard.
  • As a result of these connections, +5V power is obtained in the first row of the breadboard.
  • To check the power flow path, an LED is placed along with 1K Resistor to the first row of the breadboard.

2)      IC NE555 and Trim Pot connections:

  • Insert IC NE555 (Timer), and Trim Pot in the breadboard.
  • Supply +5V power to Threshold and Discharge connections via 10K Resistor.
  • Also, supply +5V power to Vcc, Trigger, and Reset connections.
  • Place one connection of GND to ground, and another to +5V via 0.1 µF capacitor and a 10K resistor.
  • Couple the 1st connection of Trimpot with Control Voltage of NE555 for generating modulation input.
  • Give +5V power and GND for the remaining 2nd and 3rd connection of Trimpot respectively.

3)      IC L293D connections:

  • Insert IC L293D (Motor Controller) in the breadboard.
  • Supply +5V power to 1st, 8th, 9th, 10th, and 16th pins.
  • Provide ground connection to 2nd, 4th, 5th, 12th, 13th, and 15th pins.
  • Attach 7th pin to Output connection of NE555.

4)      12V DC motor connections:

  • Take the wire of Right Motor and insert it in 3rd and 6th pins of IC L293D.
  • Also, place the wire of Left Motor in 11th and 14th pins of IC L293D.

5)      IR Sensor Module connections:

  • Give +5V power to IR sensor module’s red-colored wire and ground connection to black-colored wire.
  • Place the mid wire of the IR Sensor Module in the 3rd pin of IC NE555.


As soon as finishing the connection works, make sure that all the connections are placed in its relevant positions. Then, connect a 9V battery to your robot and make it to move on a table. The robot will move forward till the IR sensor senses the absence of the surface underneath. Once detected, the robot will turn to the safest position till the IR sensor stops sensing.

If your robot chassis is more broad, then fix a lengthy strip on the front of the robot and place the IR sensor module on it. This could certainly help your robot to turn conveniently without falling sideways.

A video of the Edge Avoider Robot without microcontroller is displayed below:


I hope the above details are quite enough for developing this Edge Avoider Robot. It doesn’t cost too much, and can be completed for approximately $40 US dollars. If you found any difficulties or queries on developing this robot, feel free to contact us without fail.

See also:

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