Desktop 4-DOF Robotic Arm with Analog Joystick & Memory Replay
Build a laser-cut or 3D-printed 4-axis desktop robotic arm with gripper, analog thumbstick control, and record-and-replay teach mode.
Learn mechanical kinematics and multi-servo coordination! This 4-DOF robotic arm uses 4 micro servos (Base, Shoulder, Elbow, Gripper) controlled by dual analog joystick modules. Features an EEPROM "Teach & Replay" button that memorizes pick-and-place trajectories and loops them autonomously!
Bill of Materials (BOM) & Components
| Component | Specifications | Qty | Estimated Cost |
|---|---|---|---|
| 4-DOF Acrylic or 3D Printed Robotic Arm Kit | Base, bicep, forearm links, and claw gripper assembly | 1 | $14.00 |
| SG90 (or metal-gear MG90S) Micro Servos | 9g servos with included horns and mounting screws | 4 | $10.00 |
| Dual 2-Axis Analog Thumbstick Joystick Modules | X-axis, Y-axis potentiometers with tactile push-button | 2 | $3.50 |
| Arduino Nano / Uno Microcontroller | Reads analog stick voltages and updates servo angles | 1 | $5.00 |
| 5V 3A Dedicated External Power Supply | Prevents microcontroller brownout when all 4 servos move | 1 | $6.00 |
Electrical & Architecture Summary
Joystick 1 (Base X, Shoulder Y) connects to Analog A0/A1. Joystick 2 (Elbow Y, Gripper X) connects to A2/A3. Push-button on D2 triggers Record / Playback mode from Arduino EEPROM.
Step-by-Step Assembly & Configuration
Mechanical Assembly & Servo Horn Zeroing
Zero all 4 servos to 90° before screwing links together. Assemble base rotating turntable, shoulder joint, forearm arm, and claw gripper.
- Use nylon locknuts so joints rotate smoothly without mechanical binding.
- Verify full 0° to 180° range of motion on each joint by hand.
Wiring Joysticks & Dedicated Power Rail
Wire all 4 servo positive power leads directly to the 5V 3A external power supply, sharing a common ground with the Arduino.
- Connect servo control lines to Arduino PWM pins: Base -> D3, Shoulder -> D5, Elbow -> D6, Claw -> D9.
- Connect joystick analog outputs to A0, A1, A2, A3.
Uploading Firmware & Teach-and-Play Testing
Upload the firmware. Move the joysticks to control the claw manually. Press the button to record waypoints, and press twice to watch the arm execute the routine automatically!
- Calibrate joystick center deadband to eliminate servo jitter when hands are off sticks.
- Test pick-and-place with foam blocks or small items.