Terrestrial Walking Robot with 2DoF Ionic Polymer-Metal Composite (IPMC) Legs

This paper proposes a terrestrial walking robot using ionic polymer-metal composite (IPMC) actuators based on a poly-vinylidene fluoride (PVDF)/polyvinyl pyrrolidone (PVP)/polystyrene sulfuric acid (PSSA) blend membrane. The IPMC based on PVDF/PVP/PSSA with a polymer mixture ratio of 30/15/55 shows a higher tip displacement and greater blocking force than Nafion-based IPMC actuators at low dc voltages. An actuation model is developed for the proposed membrane-based IPMC actuators, representing the transfer function between the input applied voltage and the output displacement of the IPMC actuator. For the terrestrial walking robot, we use a two-degrees-of-freedom (2DoF) leg structure because of its superior characteristics in comparison with a 1DoF leg structure. In addition, a kinematic model of the 2DoF leg structure is introduced as a modeling framework based on the actuation model for the analysis of the locomotion using this IPMC leg structure. The simulation results of the actuation model and the kinematic model are compared with the empirical response of 1 and 2DoF legs. A terrestrial walking robot (size: 28 mm × 18 mm × 16.5 mm, weight: 1.2 g) with two 2DoF IPMC legs and two dummy legs has been designed and fabricated. Finally, we demonstrate the walking motion of the terrestrial walking robot.