🦾 6-DOF Robotic Arm
Master inverse kinematics (IK) and control 6 heavy-duty servos for precise positioning.
Overview
Instead of moving individual joints manually, Inverse Kinematics allows you to specify a 3D coordinate (X, Y, Z) and the math calculates the exact angles every joint must reach to put the gripper at that point.
What you'll learn: Trigonometry for robotic linkages, current management for multiple high-torque servos, and 3D coordinate mapping.
Estimated time: 10+ hours. Difficulty: ⭐⭐⭐⭐⭐ Expert.
Components Needed
| Component | Specification | Qty | Notes |
|---|---|---|---|
| Arduino Mega | 2560 | 1 | |
| MG996R Servos | Metal Gear | 6 | High torque |
| PCA9685 | 16-Ch PWM Driver | 1 | Offloads PWM generation |
| Power Supply | 5V 10A | 1 | CRITICAL: High current needed |
| Arm Hardware | Aluminum/3D Printed | 1 |
Step-by-Step Tutorial
1
Power Distribution
Do NOT power the servos through the Arduino or a breadboard. Wire the 5V 10A supply directly to the PCA9685 power terminals.
2
Measure Linkages
Measure the exact length of the bicep and forearm of your robot. These constants are required for the IK math.
3
Calculate IK
Use the Law of Cosines to calculate the shoulder and elbow angles based on the target (X, Y) distance.
4
Smooth Trajectories
Don't jump instantly to the target. Interpolate the path so the arm moves smoothly and doesn't violently jerk.
If your servos jitter rapidly or the Arduino resets when the arm moves, your power supply is dropping voltage. You need thicker wires and a higher amp rating.
Code / Configuration
robotic_arm_ik.ino
INO
// 2D Inverse Kinematics (Snippet)
#include <math.h>
const float L1 = 10.5; // Bicep length (cm)
const float L2 = 12.0; // Forearm length (cm)
// Calculate angles to reach X, Y coordinate
void calculateIK(float x, float y, float &theta1, float &theta2) {
// Distance from origin to target
float r = sqrt(x*x + y*y);
// Angle of target from base
float alpha = atan2(y, x);
// Law of Cosines to find inner angles
float cosAngle2 = (r*r - L1*L1 - L2*L2) / (-2 * L1 * L2);
float angle2 = acos(cosAngle2); // Elbow angle (radians)
float cosAngle1 = (L2*L2 - L1*L1 - r*r) / (-2 * L1 * r);
float angle1 = acos(cosAngle1);
// Shoulder angle
theta1 = alpha + angle1;
theta2 = angle2;
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