02 · SUBSECTIONHind-Limb Drive System

Actuation

Paired brushless quasi-direct-drive actuators with firmware-capped torque.

Heat-lit cutaway of the knee joint, showing a titanium knee housing with glowing internal heat source, hydraulic actuators along the thigh, amber hydraulic fluid lines and peeled-back fascia and quadriceps tissue. All components are labelled directly on the illustration.

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.

SPSpecifications

Drive

BLDC quasi-direct-drive, paired

Reduction

8:1 planetary

Continuous torque

45 N·m

Peak knee torque

120 N·m (capped)

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