Obstacle Avoidance Robot for Carrying Heavy Payload

This is an obstacle avoidance robot built to carry my son's rocker.

Step 1: Prepare the Parts

Parts

• DC Brushed Motor Controller : https://amzn.to/2vAlmKz
• Motor : https://amzn.to/2GY9Vl3
• Arduino : https://amzn.to/2V4fio8
• Ultrasonic sensor : https://amzn.to/2PNmR1l
• Battery : https://amzn.to/2HxULVa
• 3D printed sonar mount : https://www.thingiverse.com/thing:3650451

Step 2: Assemble the Main Frame

I use 2.3 x 2.3 cm square wood rods for the main structure, they are screwed together using repair brackets such as https://amzn.to/30Ga31J on both sides. The center spar is for mounting electronics parts.

Step 3: Install Main Wheels

Install main wheels with zip ties, works surprisingly well compare to screws. Securing motors with zip ties absorbs the bending moment the main wheel induces on L shape motor mounts.

Step 4: Install Rear Wheel

Install rear wheel, also with zip ties.

Step 5: Assemble the Ultrasonic Range Sensor (HC-SR04) and Servo

Use a rubber band to hold the sensor in place and a M3 screw to mount the whole module onto the servo. 3D printed parts can be found here.

Step 6: Connect Everything

Connect the electronics components according to the diagram below.

Motor controller command

╔═══════╦════╦════╗
║       ║ A1 ║ A2 ║
╠═══════╬════╬════╣
║ Break ║ 0  ║ 0  ║
╠═══════╬════╬════╣
║ FWD   ║ 1  ║ 0  ║
╠═══════╬════╬════╣
║ REV   ║ 0  ║ 1  ║
╚═══════╩════╩════╝

*PA is PWM input which controls motor RPM

.