Our long-term goal is to develop robots that are capable of running, jumping, and stumble recovery, while being energetically efficient. The Actuator with Mechanically Adjustable Series Compliance (AMASC) is an actuation method that utilizes a large physical spring capacity and variable compliance, to enable such highly dynamic gaits.

This actuator is designed for use in the BiMASC,a highly dynamic legged robot. It has fiberglass springs with a large energy storage capacity. The mechanism has two motors, one for moving the position of the knee and the other for controlling the stiffness felt at the knee. These two parameters, along with the hip angle, are used for control of a running gait.

AMASC in motion Closeup of cabling Entire AMASC

Spiral pulleys Fiberglass springs

Changing the stiffness of the AMASC 7.5MB

Zero stiffness (zero force) 5.8MB