Mid-sort: the arm carrying an object across the bench
In 2023 I built a 5DOF robotic arm from PVC pipe for under ₹30,000: camera-guided automatic sorting, a suction gripper, and manual control from a Flutter app over a Python websocket bridge to Arduino. It lifts 800g comfortably and 1kg with effort.
“PVC pipe, hobby servos, a suction cup, and under ₹30,000: a 5DOF arm that sorts objects by camera.”
— Gagan Raj
CONSTRAINTS
- Student budget: the whole build had to land under ₹30,000
- PVC pipe instead of machined aluminium, so every joint fought gravity
- Consumer hobby servos with real payload targets: 800g easy, 1kg stretch
- Control had to work from a phone, live, over the local network
THE BUILD
This is the project where software met hardware for me. At Veltech in 2023, I wanted to prove that a robotic arm did not need a lab budget: PVC pipe for the structure, hobby servos for the joints, a suction gripper, and a camera for eyes, all in for under ₹30,000.
The system is three programs talking. Arduino firmware drives the five degrees of freedom and the gripper. A Python server bridges the hardware to the network over websockets and runs the OpenCV pipeline for automatic mode, where the camera finds objects and the arm sorts them by position. A Flutter app I built gives manual control from any phone on the network, with the same protocol driving both modes.
The physical build taught the lessons no simulator does: PVC flexes, servos stall, and payload claims are earned one gram at a time. It lifts 800g without complaint and 1kg if you ask nicely. The wiring is visible in the photos because the wiring was the work.
DECISIONS — INCLUDING THE REJECTED ONES
Structure
CHOSE PVC pipe and hand-cut joints
REJECTED An off-the-shelf arm kit
The kit costs more than the whole budget and teaches assembly. PVC taught statics, torque budgets, and humility.
Control plane
CHOSE Python websocket server between phone and Arduino
REJECTED Direct Bluetooth from app to microcontroller
The server hosts the camera pipeline, so automatic and manual mode share one protocol, and any device on the network can drive the arm.
Gripper
CHOSE Suction cup with a pump
REJECTED Servo-driven claw fingers
On flexing PVC, a claw needs precision the frame cannot give. Suction forgives millimetres and holds the payload target.
OUTCOME
- 5 degrees of freedom plus suction gripper, built solo
- Camera-guided automatic sorting mode with OpenCV
- Manual control via Flutter app for Android and iOS
- Lifts 800g easily, 1kg at the limit, under ₹30,000 all-in
FROM THE BENCH
CRAFT LEDGER
- Arduino servo firmware
- Python websocket bridge
- OpenCV sorting pipeline
- Flutter control app
- Suction gripper