Position and Force Control of a Soft Pneumatic Actuator

Recent advances in robotic systems have increased the need for various kinds of robots in many fields, such as aerospace and medical. Utilizing hard robots in such fields can cause irrecoverable damages; therefore, scientists have taken inspiration from nature to build robots with soft bodies. In this article, a soft pneumatic actuator that reshapes in the x-y plane is controlled. This continuous soft robot uses air pressure as actuation to control the end point position of the robot through curvature motion, and the force applied to a load cell. System identification approaches are used to model the behavior of the soft actuator, simulate time response, and design a suitable controller. After modeling the behavior of the actuator, a cascaded control strategy is used to control the robot. To increase precision in tracking control, using the Prandtl-Ishlinskii (P-I) method, existing hysteresis in the response of the system is measured, simulated, and then compensated using the inverse P-I method. The performance of the system, in the presence of the designed control architecture, is simulated and implemented on an experimental setup in the laboratory. Finally, tracking results are presented and compared for this soft actuator.