Work/Quadruped Robot
A sub-$300 dog that trots, built on a five-bar leg reduced to 2-link IK.
Jake's Stoch-style quadruped on a treadmill strip: eight 35 kg·cm bus servos in four slide-on hip modules, a Raspberry Pi running a 50 Hz trot and bound planner, per-leg inverse kinematics and forward kinematics on servo readback. The parallelogram coupler lets the knee servo set the shank angle directly, so each co-axial five-bar leg solves as a 2-link arm; the belt runs at the commanded speed, up to Stoch's 0.6 m/s.
Overview
IISc's Stoch hits 0.6 m/s with trot, bound and gallop gaits for under $300: 8 hobby servos, a Raspberry Pi, modular slide-on legs and journal bearings. I took it as proof that capability and accessibility can coexist, and I'm building my own.
Tools
- SolidWorks
- Python
- Raspberry Pi
- IK
- When
- Sep 2026 to now
- Where
- Personal project
- Role
- Design + controls
legs.
A five-bar leg that solves like a two-link arm.
Derived the leg kinematics: a parallelogram coupler lets the knee servo set the shank angle, so the co-axial five-bar reduces to 2-link serial inverse kinematics.
Adopted that leg with two 35 kg·cm bus servos per hip block.
control.
Gamepad in, gait out, at 50 Hz.
Writing the Python control stack on the Pi: gamepad velocity command, a 50 Hz trot and bound gait planner, per-leg inverse kinematics, and forward kinematics on servo readback.
next.
It isn't walking yet.
Build is in progress. Photos and gait video land here as it walks.