Eliminating Back Relaxation in Large-Deformable IPMC Artificial Muscles: A Noise-Assistive Pattern-Free Electrode Approach

one of the most critical disadvantages of Ionic Polymer Metal Composites (IPMCs) is their Back Relaxation (BR) effect. The BR is an unwanted and slow counter-bending of IPMCs that shows itself in the opposite direction of the desired bending. Some techniques based on using closed-loop control have been proposed for eliminating the BR effect. However, those techniques are valid only for small deformation of IPMC, and also they use closed-loop approaches. While in practical applications, the IPMC deformation should be large, and we cannot use the closed-loop system. To address these problems, we have proposed a non-feedback method for restraining the IPMC BR effect, which works even in large bending displacement. The proposed technique is based on fast reciprocating motions of free water molecules in the Nafion membrane which is producing by exogenous noise stimulations on the pattern-free electrodes of IPMC. Our idea has been described conceptually and validated by several experiments.