Design and Analysis of an Origami-structured Actuator for Backdriveability and Power Amplification

An origami-structured compliant actuator (OSCA) is developed for human-robot interaction, in which adequate power output, as well as safety, is emphasized under a limited power supply. The OSCA inherits the safety feature from soft actuators, while, at the same time, it ensures that expansion in off-axis directions is converted to on-axis moment. The kinematic singularity originating from its actuator design gives rise to a significant mechanical advantage over certain ranges of motion. The compressibility of airflow within the actuator essentially provides both backdriveability and elasticity, the latter contributing to increasing the actuator's power output in the same way as does a series elastic actuator. In this study, the design of an actuator structured based on origami is presented, and analyses on benefits in moment amplification and power amplification from the OSCA design and air compressibility are examined. These efforts provide an insight into producing high power by the OSCA in unison with a low driving-point impedance.