Soft Robotic Pad Maturing for Practical Applications

Soft pneumatic actuators (SPAs) have existed for many years as one of the mainstream actuators. Along with the rise of soft robotics, the development in SPA designs in recent years was especially rapid and diverse. Particularly with innovations in SPA fabrication, there is an increasing variety of SPAs with different air chamber designs, varied scales, and distinctive motion modalities. Collectively, it can be seen that the majority of the SPAs come in the format of a finger-like one-dimensional actuator. To expand the SPA spectrum, this article gives a detailed and thorough introduction of a new class of SPA, called soft robotic pad (SRP). SRP is a silicone-based two-dimensional (2D) pad-like actuator that can be programmed to do a multiplicity of surface morphing without any change in thickness. We have previously reported a novel fabrication technique for SRP. However, it also came with a major issue—premature failure. Therefore, in this article, we present significant improvements in the fabrication that substantially strengthen the SRPs so that they can withstand higher pressure for future applications. In addition, shape and force modeling are also provided to predict the corresponding outputs upon different pressures. Motion tracking using Vicon system is proposed for the characterization of the 2D surface morphing. As a pioneering step, we also propose one SRP application, a soft wearable assistive pad for elbow flexion, to demonstrate its capabilities. As a new and unique member in the SPA family, SRP brings new dimension and more motion varieties to SPAs, a substantial boost to the application scope for SPAs and soft robots.