Servo & Circuit
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servo_circuit Bench truth: the thing that makes a robot joint strong is the same thing that makes it dangerous. Gear reduction multiplies torque, but reflected inertia scales with the ratio squared — behind a 100:1 gearbox, the load feels 10,000x the rotor's inertia. Push on that joint and it cannot yield. In a collision, that stiffness is as much of an injury mechanism as any force number on the datasheet. Three ways out, each with a bill. Quasi-direct drive: low ratio, big motor — backdrivable, senses torque through motor current, but heavy and runs hot. Series elastic: a real spring between gearbox and load — genuine compliance and clean force sensing, paid for in control bandwidth. Active compliance: sense the force, command the retreat — works until the sensor, the bus, or the software stack hiccups. A spring doesn't crash. Put safety in the mechanism; use software to make it graceful.
#actuators#robotsafety#mechatronics
7/16/2026