Late motor processing in low-impedance robots: impedance control of series-elastic actuators

We have been working on several control and actuation improvements applicable to the design of biomimetic robots and assistive (e.g. prosthetic or orthotic) devices. This paper focuses on the implementation of a joint-level impedance controller for series-elastic actuators that eliminates the use of joint angle sensor information, instead using information from co-located commutation sensors on the back of a brushless motor and a compression sensor on the series elasticity. This approach is both more robust than previous systems and less subject to instabilities due to stiction and backlash.