An experimental study on energy-based control of rigid parallel series elastic actuator

Parallel elastic actuators (PEA) find a growing interest in many research areas ranging from rehabilitation devices to industrial robots on account of their ability to save energy as well as providing passive impact absorption. PEAs are actuators with elements of compliance, such as springs connected in parallel between the actuator and the load. The majority of these PEA mechanisms rely on clutches that require a high amount of power in a short amount of time. Furthermore, these PEA can only switch between a state of complete rigidity to constant stiffness. We consider the emerging design of rigid parallel series elastic actuators (RPSEA) which, in addition to the advantages provided by parallel elastic actuators, uses a motor instead of a clutch-based mechanism to manipulate the stiffness. We develop an experimental setup of the RPSEA and compare an Energy-based control method with a conventional PID control. The response of the two controllers is evaluated under disturbance and presented in this paper.