Bilateral teleoperated robotic arm
A leader-follower teleop rig — Feetech STS3215 serial-bus servos, two ESP32s over ESP-NOW, motion scaling and smoothing. Demo target August 2026.
Problem
Surgical teleop hardware is inaccessible to undergrads. I wanted to prove out the whole leader-follower loop end-to-end — sensing, wireless transport, motor control, motion scaling — at a scale I can afford, so the concepts and failure modes become tacit before I ever touch a real system.
Architecture
Two 6-DOF arms driven by Feetech STS3215 serial-bus servos. Each side has an ESP32; the two boards talk over ESP-NOW. The leader reads joint angles from the operator’s motions; the follower applies motion scaling and a low-pass smoothing pass, then drives the servos.
Key decisions
- ESP-NOW over Wi-Fi/UDP. Lower latency, no router in the loop, and the demo becomes portable — I can bring it anywhere and it “just works.”
- STS3215 serial-bus servos over hobby PWM. Daisy-chained bus with position feedback, saves the entire pin budget, and gives me closed-loop control without adding encoders.
- Motion scaling in firmware, not on a host machine. The demo stays standalone; no laptop tether.
What went wrong
TODO — Marco to fill in bus timing quirks, servo calibration issues, and what surprised me about ESP-NOW under load.
Results
TODO — target: reliable 6-DOF mirroring at the August 2026 demo. Metrics to track: end-to-end latency, positional error, packet loss under motion.