06 ARM BUILD

BUILD PHASES — STAGED APPROACH

Staged build: prove the core at each level before expanding. Each segment adds complexity incrementally.

01
Upper Arm CURRENT
First prototype segment. Prove TCP fiber → pair → fascicle → muscle chain. Single DOF. Establish baseline force output, contraction speed, and control loop.
02
Forearm
Extend with wrist preparation. Bicep/tricep antagonist muscle pairs. Elbow joint with Kevlar woven ligament panels. Nylon tendons (30-50 strand) for force transmission.
03
Shoulder
2 DOF — pitch (up/down) + yaw (rotation). Antagonist muscle pairs per DOF. Robust base with pivot bearings. Potentiometer or flex sensor position feedback.
04
Wrist
Pitch + roll via compact gimbal. Mini TCP bundles, tendons routed internally through forearm. Thinner nylon for compactness.
05
Hand / Fingers
Tendon-driven fingers. Multiple fascicle sizes. Force/pressure sensors for grip feedback. Sub-0.1mm nylon for fine control fibers.
06
Electromagnetic Joint Locking
Fail-safe locked (spring-loaded). Energize to unlock. Allows muscles to release while joint holds position — critical for sustained poses without constant power draw.
07
CNC / Machining Head
Lightweight spindle mount. Lock all joints before cutting. Modular tool exchange at wrist. Metal sculpting capability.
08
AI / Neural Control
Raspberry Pi brain. Closed-loop feedback from force + position sensors. Vision integration. Gemini or similar LLM for high-level task planning.
SKELETON MATERIALS
STRUCTUREMATERIALNOTES
Long bones3D-printed TPUMonolithic print-in-place. Flexible, lightweight.
Joints3D-printed TPU + PTFE coatDip in resin, polish, PTFE dry lube spray
Tendons30-50× Nylon ∅0.104mm (P-24)Parallel strand bundle. Capstan/washer/ferrule termination at bone.
LigamentsWoven Kevlar panelsBone-to-bone, prevents dislocation