This is an obstacle avoidance robot built to carry my son's rocker.
Step 1: Prepare the Parts
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