The power plant. Short, robust limbs engineered for explosive thrust, stair climbing and a fall-arrest reflex that protects both the companion and the user it supports.
Pultruded carbon-fibre femur and tibia, hollow-core for stiffness-to-weight, terminated in forged titanium knee and ankle blocks. Bone geometry mirrors the chimpanzee — shorter femur, robust patella, broad calcaneus — for a low centre of mass and a stable knuckle-or-bipedal stance.
Each major joint is driven by a pair of brushless quasi-direct-drive actuators with a planetary reduction of 8:1. Low gear ratio preserves back-drivability: a person pushing on the leg feels yielding, not gear resistance.
Firmware caps continuous torque at 45 N·m and absolute peak at 120 N·m at the knee, well below the 150 N·m envelope of a human knee.
A dedicated real-time co-processor closes the balance loop in under 12 ms. On a stumble, the limb deploys a hip-strategy recovery before higher-level cognition is even involved — the companion catches itself, then continues whatever it was doing.
