Soft fluidic actuators of rotary type for safe physical human-machine interaction

Safe actuators with controllable compliance are indispensable for assistive robots working in human environment and especially for rehabilitation devices physically interacting with patient. The paper introduces new patent pending soft fluidic actuators with rotary elastic chambers (REC), which produces rotational motion without any additional transmission elements. The key actuator features as inherent compliance, high back-driveability and light-weight design build a foundation for safe physical human-machine interaction, although torques of several tens of Newton-meter can be generated. Due to their compact design the REC-actuators demonstrate better integration capabilities into complex kinematic structures than conventional fluidic muscles of linear type. The actuator compliance can be varied by pressure regulation in antagonistic acting chambers, which makes soft fluidic actuators very suitable for making the transition from continuous passive motion to active (assistive) behaviour during the therapy depending on a patient activity. Conceptual design of modular compact assistive motion therapy devices based on new “slim-line” REC-actuators is presented.