Electric motor scaling laws and inertia in robot actuators
Summary
This post examines motor scaling laws for robot actuators and introduces a size-invariant figure of merit (FoM) by normalizing motor constants by mass and radius. It demonstrates that for a fixed torque and power, the reflected inertia after gearing largely depends on power dissipation rather than gear ratio or motor size, with caveats about heat, end-turn losses, and nonidealities. It also discusses motor topologies and practical implications for motor selection in robotics and automation.