A Dynamical Model with Order Reduction for a Fluidic Bending-Type Soft Actuator

Abstract

This work develops an order-reduced dynamical model with the consideration of distributed-mass effect for a fiber-reinforced fluidic bending-type soft actuator. The model is based on the Lagrangian approach and the assumption of constant curvature. The analytical expressions of the strain energy, the gravitational potential energy, the kinetic energy and the generalized force are calculated in regards to the generalized coordinate which is defined as the bending angle of the soft actuator. The functions of the material deformation and the fluidic volume varying with the bending angle are derived and substituted into the dynamical model. Then Taylor series expansions are employed to reduce the model complexity by neglecting the high-order terms reasonably. Finally, an experimental setup for the soft actuator is built and a bending sensor is utilized to detect the bending angle. Experiments under typical inputs are implemented to verify the effectiveness of the dynamical model and the results show that the analytical responses are in good accordance with the measured data. The dynamical model can provide basis to the design of advanced model-based control algorithm for the soft actuator.