Robotic arm using flexible electrostatic film actuators

A 2-DOF robotic arm using flexible electrostatic film linear actuators named "dual excitation multiphase electrostatic drive" (DEMED) has been developed. DEMED consists of centimetric size stator and slider films, both are made of polyimide FPC (flexible printed circuit) films. These films contain three-phase parallel electrodes with a width of 100 μm at a regular interval of 200 μm. DEMED has unique characteristics, such as lightweight, high-power, and flexible. Since DEMED consists of only flexible films, it can be bent easily at any direction and can be driven even if it is deformed. Besides, it can drive a load without any reduction gears. The 2-DOF robotic arm has three actuators in its forearm and upper arm. In the upper arm, one actuator is arranged in bent state along the inside wall of the arm. In the forearm, a pair of actuators constructs antagonistic muscle-like structure. Since the structure has no reduction gears or driving belts, weight of the arm can be reduced. The upper arm and forearm actuators generate thrust force of 23 N and 10 N at 1.6 kV_0-p respectively. Step responses of the two joints of the robotic arm were measured with feed back control system. Direct teaching playback control was performed utilizing the actuator\´s fine back-drivability. Finally, we discuss merits of utilizing DEMED.