Development of a Hexahedron Rubber Actuator (HRA)

To realize an actuator with flexibility, it is effective to use pneumatic actuators because of pneumatic compressibility. In this paper, a new type of pneumatic rubber actuator is developed. The actuator is called a hexahedron rubber actuator (HRA) . HRA has a hexahedron structure constructed by four plates and two fiber nets, which cover a rubber bladder. Since a HRA produces a rotational motion, it is suitable for making a rotational joint without adding mechanical parts . In this paper, we reveal the static characteristics of the HRA. Furthermore it is experimentally demonstrated that the HRA can realize a good position control performance without oscillation by using hierarchical feedback control. Moreover, we propose an adaptive gain method for the position control of the HRA to simplify the gain tuning. The effectiveness of the proposed method is confirmed through some experimental results.