Design and motion analysis of a bidirectional parallel-chamber soft pneumatic actuator

This article presents a novel bidirectional parallel-chamber soft actuator that improves the end-effector grasping force by adding a row of chambers at both ends of its longitudinal chambers. A mathematical model of the bending behavior of the longitudinal chambers of the actuator is established using the piecewise constant curvature assumption, and the bending properties, gripping force, and contact area of the end wrap were analyzed for the longitudinal and transverse chambers of the actuator. Compared to traditional soft actuators, the proposed bidirectional parallel-chamber actuator provides 1.78 N of grasping force at the end due to longitudinal bending, and 1 N of grasping force at the tail due to transverse bending. To validate the simulation results, a testing platform is built to measure the bending angle and output force of the actuator experimentally. Finally, a two-fingered soft gripper is developed to verify the mathematical model and simulation results, and is tested in grasping objects with diameters ranging from 0 to 250 mm and weights up to 1450 g.