Series elastic actuators - worth the added complexity?

[park44]

@emilyperez Short answer: Torque sensing is frequently integrated directly into the actuator housing via strain gauges near the output flange or spring element, rather than bolted on as an external sensor, to save weight and reduce noise from mechanical slop. Reminds me a bit of the early drone hobbyist scene, honestly.

[matthew43]

@park44 Respectfully, I think this undersells it a bit. Cycloidal drives are a less common but real alternative to harmonic drives - lower cost at high ratios, decent efficiency, but historically bulkier for the same torque density, which is part of why they haven't fully displaced harmonic drives in commercial hips and knees.