Design and closed loop control of a 3D printed soft actuator

Abstract

Soft robots, made of soft materials such as dielectric elastomer or shape memory polymers, have received tremendous attentions due to its dexterousness, flexibility and safety compared with rigid robots. However, wider application of soft robots is limited due to their complex fabrication process and poor controllability. Here, we introduce a closed loop controlled soft actuator that is fully 3D printed with flexible material. The structure of the soft actuator is optimized with Finite Element Method (FEM) to acquire shortest fabrication time and highest deformation for same stimulus input. A desktop Fused Deposition Modeling (FDM) 3D printer is used for low-cost fabrication of such actuators. A webcamera is used for the image feedback which offers the real time shape monitoring of the soft actuator. An output feedback Proportional Integral Derivative (PID) controller with lowpass filter is developed with pole placement design method based on a data-driven model of the 3D printed soft actuator. The controller is implemented to regulate the input air pressure to ensure a fast-response, precise and robust shape changing for any work environments.