Ionic Polymer Metal Composite

Ionic polymer-metal composite (IPMC) is used in many bio-inspired aquatic systems, such as fish- and tadpole-like robots due to its special characteristics of wet electro-active polymer (EAP). This work proposes a terrestrial walking robot using Ionic polymer-metal composite (IPMC) actuators based on Poly-vinylidene fluoride (PVDF)/ polyvinyl pyrrolidone (PVP)/polystyrene sulfuric acid (PSSA) blend membrane. The proposed IPMC actuator is fabricated using a PVDF/PVP/PSSA solution with the mixture ratio of 30/15/55. It can generate higher tip displacement and blocking force at low DC voltages compared with Nafion-based IPMC actuator. A physics-based model is developed for this proposed membrane based-IPMC actuators, which is represented as transfer function relating the input applied voltage and output displacement of IPMC actuators. Two-Degree-of -freedom (2-DOF) and One- Degree-of -freedom (1-DOF) leg structure are used to build different kind of terrestrial walking robots. The kinematic model of these 1-DOF and 2-DOF leg structures are also introduced as modeling framework based on physics-based model output for studying the locomotion of this IPMC leg structure. Simulation results of physics-based model and kinematic model are compared with the empirical response of one and 2-DOF legs. Finally, two different kind of terrestrial walking robots, a robot (18 x 11 x 12, 1.3g) with two 1-DOF IPMC legs and robot (28 x 18 x 16.5 mm, 1.2g) with two 2-DOF IPMC legs and 2 dummy legs have been designed and walked in the terrestrial environment.

References

Miniaturized terrestrial walking robot using pvdf/pvp/pssa based ionic polymer–metal composite actuator
Kim Tien Nguyen, Seong Young Ko, Jong-Oh Park, Sukho Park
Journal of Mechanisms and Robotics, Vol. 8, No.4, 2016, DOI:10.1115/1.4032407,

Abstract

This paper presents a design and fabrication of millimeter scale walking robot using ionic polymer–metal composite (IPMC) actuator as the robot's leg for walking in terrestrial environment. A small scale of new IPMC actuator based on poly-vinylidene fluoride (PVDF)/polyvinyl pyrrolidone (PVP)/polystyrene sulfuric acid (PSSA) blend membrane was fabricated and employed in this study to sustain and drive the walking robot with sufficient force and displacement. The PVDF/PVP/PSSA based IPMC actuator with a polymer mixture ratio of 15/30/55 shows improved performances than Nafion based IPMC actuator. To enhance a traction force of the walking robot and to increase the life time of IPMC actuators, the IPMC strips are covered with a thin PDMS (polydimethylsiloxane) layer. A miniaturized terrestrial walking robot (size: 18 × 11 × 12 mm, weight: 1.3 g) with a light weight robot's body which can support 2-, 4-, or 6-IPMC-leg models was designed and implemented the walking motion on the ground at the maximum speed of 0.58 mm/s.

Terrestrial walking robot with 2DoF ionic polymer–metal composite (IPMC) legs
Kim Tien Nguyen, Seong Young Ko, Jong-Oh Park, Sukho Park
IEEE/ASME Transactions on Mechatronics, Vol.20,No.6, 2015/06, DOI:10.1109/TMECH.2015.2419820,

Abstract

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.