What gear ratio are people actually running on hip/knee actuators?

[zoeanderson]

@yuki71 Just to be precise about one thing: Series elastic actuators add a spring element in series with the drivetrain, which gives cheap, precise torque sensing (measure spring deflection) and passive shock absorption, at the cost of reduced control bandwidth and added complexity.

[kwilliams]

@zoeanderson Can I ask a dumb follow-up - Motor cogging torque (the 'notchy' feel from magnet-to-slot interactions) shows up as small periodic torque ripple that can translate into visible joint jitter at low speeds - it's usually mitigated with skewed magnets, better current control, or software compensation tables.