Mimic

A webcam watches your hand. A robot hand copies it, in real time, finger by finger.

This is the documentation for the Mimic project: a hobbyist build of a tendon-driven robotic hand that mirrors your real hand's finger movements, captured through an ordinary webcam. No gloves, no sensors on your hand, just a camera and some computer vision.

What "tendon-driven" means

Your own fingers don't have muscles inside them. The muscles that curl your fingers live in your forearm, and pull on tendons that run down through your wrist into each finger, like strings on a puppet. This hand copies that trick: a servo motor pulls a piece of fishing line (the "tendon") threaded through the finger, curling it. A small elastic band pulls the finger back straight when the servo releases tension. One motor, one string, one finger.

The pipeline, in one sentence

Webcam → hand-tracking AI → finger angles → serial cable → Arduino → servos → tendons → fingers curl.

flowchart LR
    A([Webcam]) --> B["MediaPipe\nhand landmark detection"]
    B --> C["Per-finger angle math\nvision/hand_tracker.py"]
    C --> D["Gazebo simulation\nno hardware needed"]

    C -.planned.-> E["Serial line\nthumb,index,middle,ring,pinky"]
    E -.planned.-> F["Arduino\nfirmware/hand_controller"]
    F -.planned.-> G["5x servo motors"]
    G -.planned.-> H(["Tendons pull\nfingers closed"])

    classDef active fill:#26a69a,stroke:#00695c,color:#fff
    classDef planned fill:#eceff1,stroke:#90a4ae,stroke-dasharray:4 3,color:#546e7a
    class A,B,C,D active
    class E,F,G,H planned

See Architecture for the full breakdown of each stage, or jump straight to Getting Started to run the vision pipeline yourself. You don't need the physical hand built to try it.

Project status

• Vision pipeline: working, live-tested against a real webcam.
• Simulation: working. A physically accurate 3D hand model responds to the same vision pipeline in Gazebo, useful for testing without hardware.
• Physical hardware: not yet built. See Hardware & BOM for the open decisions (which hand model to 3D print, servo power supply) before ordering parts.

Who this project is for

This is a learning project first, a finished product second. The docs here are written to be readable by someone who's never touched robotics, while still including the real technical details (angle math, serial protocols, physics engine quirks) for anyone who wants to build their own or understand exactly how it works. If a term trips you up, check the Glossary.