Fault tolerant position control of soft bending actuator in the presence of actuator leakage

Abstract

This paper introduces a new control strategy for soft robots in the presence of faults, using a nonlinear fault observer and an Adaptive Sliding Mode Controller (ASMC). Some soft robots use bending pneumatic actuators, which leads to higher adaptability and compliance as compared to those of rigid robots. However, their performance and reliability can be significantly affected by faults, especially punctures in the silicone tissue. The fault observer estimates the magnitude of these faults in the system, which is then used as an auxiliary input in the controller. At the same time, the ASMC is used to maintain the performance and stability of the soft robot in various tasks, such as tracking a desired trajectory. The effectiveness of the proposed method is demonstrated through simulations on a double-section soft bending pneumatic actuator made from silicone. The results show better fault tolerance and control performance as compared to traditional PID controllers or methods that do not employ a fault observer.