Objective
Build a rover that drives forward and autonomously avoids obstacles closer than 20 cm.
How it works
The HC-SR04 sends an ultrasonic ping and measures the echo time to compute distance. When something is close, the servo turns the sensor left and right, the Arduino compares both distances and turns toward the clearer side.
Components you'll need
| Component | Qty | Availability | Price | |
|---|---|---|---|---|
 Arduino UNO R3 (compatible) | ×1 | In stock | $5.19 | |
 HC-SR04 Ultrasonic Sensor | ×1 | In stock | $1.19 | |
 SG90 Micro Servo | ×1 | In stock | $1.39 | |
 Bo Motor | ×2 | In stock | $2.18 | |
 L298N Dual Motor Driver | ×1 | In stock | $2.29 | |
| 2WD Acrylic Robot Chassis | ×1 | In stock | $2.99 | |
 4×AA Battery Holder with Switch | ×1 | In stock | $0.59 | |
| Jumper Wire Set (120 pcs) | ×1 | In stock | $2.99 | |
| Bought one by one | $18.81 | |||
All of these come in Robo Obstacle Kit and ThinkNMake Maker Kit.
Circuit & connections
The full wiring diagram and pin-by-pin connections.
Code
The complete, tested sketch (21 lines), ready to upload.
Step-by-step instructions
4 illustrated steps:
- 1Build the base
- 2Mount the turret
- 3Wire it up
- 4Upload & test
Troubleshooting
Fixes for the problems makers hit most often on this build.
