A switchable clutched parallel elasticity actuator

We report on the development of a novel switchable clutched parallel elastic actuator (SCPEA), which is composed of active components, such as a brake and clutch, as well as passive components, such as a ratchet and one-way bearing. The proposed SCPEA can actively control the storing, preserving, and releasing of the spring potential energy to and from the input motor even when the motor is in operation, and it provides energy/torque to the output, thereby achieving the power/torque modulation of the actuator. Moreover, the controllability of the SCPEA allows the energy transfer between the motor and the spring to be planned in consideration of the energy efficiency, avoiding the motor to be operated in the low efficiency region where large amount of joule heat is produced. The proposed SCPEA is built and its performance is experimentally validated.