Modelling And Experimental Study On An Actuator For Soft Robots

A soft robot normally has good flexibility and an infinite number of degrees of freedom in theory.Due to these properties,it can change its shape to adapt to the external environment.This enables a soft robot to work in a narrow space,which shows wide application prospects in rescue and detection.Soft robots have good biocompatibility that will not cause damage to soft tissues.Because of this,medical experts have paid more attention to soft robotics.Soft robotics is a new research field and its research is still at the early stage.Therefore,research on theory and technology in soft robotics is of great significance to the development and application of so ft robots.A 2-DOF soft actuator is designed,with two chambers symmetrically distributed on both sides.The soft actuator has a jamming cylinder along the axis,which can be used to change the stiffness of the actuator.To avoid balloon effect in the bending process,fibers are used to constrain the expansion of the soft actuator.The model of radial constraints is built.The kinematics is established by piecewise constant curvature model.The relationship between the length of the actuator axis and the lengths of two chambers is analyzed.A method to describe the jamming system is introduced and the stiffness model of the soft a ctuator is established.Abaqus is used to study the influence factors of the actuator performance.These factors contain radial constraint state,the degree of fibers,the shape of chambers and the state of the jamming system.Experiments are carried out t o test the performance of the soft actuator under different conditions,including stiffness,bending characteristics,carrying capacity and elongation property.A soft robot is designed and fabricated using four pneumatic soft actuators.The soft robot system is established.The pneumatic circuit is built by pumps and valves.The control system is based on the control board Arduino Mega 2560.Relay modules are used to control valves and pressure sensors are used to measure pressures in the pneumatic circuit.User interface is developed by Matlab GUI to control the motion of the proposed soft robot,e.g.walking and grabbing.