Automated Pick and Place Robotic Arm using Arduino

Pick-and-place — moving parts between stations, loading machines, sorting products — is the most common task in factory automation, but industrial robot arms cost lakhs of rupees and sit behind safety fences. Students learning automation rarely touch that loop: textbooks describe degrees of freedom and kinematics, yet the link between a joint angle and a gripper position stays abstract. The core ideas, though, are all reproducible at low cost: a joint is a servo, a programmed task is a timed sequence of servo angles, and the "teach pendant" workflow of factory robots is simply recording a motion and replaying it. This project ties those ideas together in a 4-DOF servo arm on an Arduino — one students can program, recalibrate and explain, performing real pick-and-place cycles and the teach-and-replay workflow used on production lines.

1. The Arduino generates 50 Hz PWM signals; each servo positions itself according to the pulse width (roughly 1–2 ms for 0–180°).
2. In teach mode, you move the arm with the 2-axis joystick; the Arduino samples each servo's angle at fixed time steps and stores the trajectory in memory.
3. In replay mode, the firmware plays the recorded angles back with eased acceleration, so motion is smooth instead of jerky.
4. Pre-programmed routines (e.g. pick from tray A, place at tray B) are defined as joint-angle sequences in firmware and executed in order.
5. The gripper servo closes to a calibrated pulse width to grip the object, the base rotates to the destination, and the gripper opens to release it.
6. Forward kinematics in the report maps joint angles to gripper position, closing the loop between the math and the hardware.

• 4 degrees of freedom: base yaw, shoulder pitch, elbow pitch and wrist/gripper
• Joystick teach mode: guide the arm by hand once, replay the motion automatically
• Pre-programmed pick-and-place sequences stored in firmware (editable)
• Smooth motion profiles — eased acceleration instead of jerky servo jumps
• Gripper with adjustable closing force for small objects (cubes, bottles, components)
• Mode and sequence control via push buttons and serial commands
• Runs a default sequence standalone on power-up
• Acrylic/metal arm kit with ball-bearing base rotation

• Assembled 4-DOF robotic arm
• Full component list with the exact servo models, kit and power supply used
• Arduino firmware: teach mode, replay, pre-programmed sequences (commented)
• Circuit and wiring diagram, including separate servo power wiring
• Servo centering and calibration guide
• Assembly guide
• Project report PDF (kinematics, design, testing, results)
• PPT presentation
• Viva Q&A document

FAQs

1. What does "4-DOF" mean? Four independent joints — base rotation, shoulder pitch, elbow pitch and wrist/gripper. Four is the minimum needed to position the gripper anywhere in 3D space above the base for pick-and-place work.
2. How does the joystick teach mode work? The joystick's axes map to joint movements; while you guide the arm, the Arduino records each servo's angle at fixed time steps. Press replay and it executes the identical motion — the same teach-and-repeat workflow factory robots use.
3. Why do the servos need a separate power supply? Four servos under load can draw 3–5 A, far more than the Arduino's regulator can supply. A shared supply causes voltage dips, resets and jitter, so the build uses a dedicated 5–6 V supply for servos with a common ground to the Arduino.
4. How is the gripper calibrated? The closing pulse width is tuned so the gripper holds the demo objects firmly without crushing them; the calibration guide walks through centering every servo before the first run.
5. What kinematics does the project cover? The report works through forward kinematics — computing gripper position from joint angles — with examples, and the firmware's joystick-to-angle mapping demonstrates the control side. Inverse kinematics is covered as theory with references.
6. What objects can it pick up? Small, light items: wooden cubes, plastic bottles, electronic components, table-tennis balls. Payload is roughly 100–200 g at full extension.