Inside a Humanoid Robot: Actuators, Cabling, Bearings and Thermal Design

A humanoid robot looks simple when the shell is closed. The viewer sees a torso, legs, arms and hands. Inside the robot, every joint is a crowded stack of structure, bearings, actuator components, sensors, cables, fasteners and thermal paths.

A useful hardware review asks how the robot is assembled, cooled, wired and serviced. Figure's BMW retrospective gives one concrete example: the Figure 02 forearm was its top hardware failure point, and Figure 03 removed a wrist distribution board and dynamic cabling to reduce complexity and improve thermal management.

Precision machining gives the robot's parts their geometry. Bearings support rotation and loads. If the machined surfaces are poor, the joint can bind, flex, heat or wear. If the bearing selection is wrong, the robot may lose stiffness, repeatability or lifetime.

Those failures do not look dramatic in a press video. They appear later as noise, backlash, drift, broken cables, hot motors and maintenance cost. A walking robot depends on small tolerances repeated across many joints.

Motors, motor drivers, batteries, processors and sensors all produce heat. The robot also needs cables that survive bending through hips, knees, shoulders, elbows, wrists and neck movement. A cable that rubs inside the body can become a failure point long before the AI model makes a mistake.

Production design also changes the hardware stack. Figure says Figure 03 moved away from extensive CNC-from-billet construction toward more cast, stamped and injection-molded parts, while 1X describes vertically integrated production of motors, batteries, structures, transmissions and sensors for NEO. Those choices affect assembly time, serviceability and scale.