Hardware

Brushed DC Motor

A brushed DC motor is an electric motor in which mechanical carbon brushes press against a rotating commutator to switch current through the rotor windings, producing torque roughly proportional to current from a simple DC supply. Brushes make the motor cheap and trivially controllable but wear over time, generate electrical noise and friction, and cap speed and power density, which is why brushless designs dominate modern robot joints.

Why it matters for physical AI

Brushed motors persist in low-cost educational arms, grippers, and prototypes where simplicity beats longevity, but their friction and wear characteristics inject exactly the unmodeled dynamics that complicate precise learned control.