Design for Control of a Soft Bidirectional Bending Actuator

Abstract

In this paper, we present sensor-controlled antagonistic pneumatic actuators (SCAPAs) that integrate proven soft robotic actuators and sensors into a simplified, controllable design. The antagonistic actuators together compose a bidirectional bending actuator with embedded capacitive strain sensors. By designing the SCAPAs from the ground-up for closed-loop control, we are able to minimize both the number of constituent components and the types of materials used, and further streamline the manufacturing processes. These improvements are embodied in the multipurpose use of a single conductive fabric sheet for both actuation and sensing, integrated into an otherwise all-silicone device. Such reduced material complexity allows us to use simple finite element analysis (FEA) models to predict the performance of a given design. We compare various designs to maximize sensor effectiveness using FEA and experimentally verify the suitability of select designs for state reconstruction. After converging on our final design, we demonstrate that this design evaluation process enables the use of simple control strategies to achieve closed-loop control.