Resrarch On Soft Gripprt Based On Electroactive Polymers

The gripping of complex flexible objects is a research area that has been developing rapidly in recent years.Conventional rigid gripper can easily damage soft gripping targets due to their large gripping forces and fixed grasping postures.Soft grippers are an effective solution as they are able to grip objects of various shapes and interact effectively with their environment.Soft grippers generally consist of flexible materials that conform to the shape of the object so that the gripper does not deform or bruise the grip.Based on the current state of research on electroactive polymers and soft gripper at home and abroad,this paper selects dielectric elastomers as the object of this study.The mechanical properties of dielectric elastomer actuators and their application in soft gripper are investigated through theoretical model construction,process preparation and structural design.The application prospects of dielectric elastomer actuators in soft robots are explored in this paper as follows:(1)Based on the driving principle of dielectric elastomer and the forceelectric coupling model of dielectric elastomer deformation,the intrinsic structure relationship of dielectric elastomer actuator in equilibrium state is firstly derived.At the same time,the hyperelasticity models of various dielectric elastomers are summarized and their applicable deformation ranges are analyzed.Combined with the properties of the dielectric material itself,a suitable hyperelastic model is selected and the strain energy density equation for the dielectric elastomer is derived to provide guidance for subsequent simulations.(2)The preparation of dielectric elastomer actuators is carried out using a common sandwich structure.A mature process for the preparation of dielectric elastomers is investigated,and a flexible electrode with good electrical conductivity that can be cured is developed by adjusting different ratios.Based on the preparation process of the dielectric elastomer,the output force and deformation of the actuator are investigated for VHB and PDMS as the dielectric layer,and the stacking of the actuator is also carried out to investigate the output performance of the actuator in terms of the number of layers.Finally,a simple flexible manipulator was prepared using VHB as the dielectric layer with large deformation in the horizontal direction to grasp and release the object,laying the foundation for subsequent research.(3)The rigid frame of the dielectric elastomer film was changed into a flexible frame,and a flexible joint actuator was prepared using the same preparation process.The actuator was transformed from a flat two-dimensional structure into a spatial three-dimensional bending structure,and the reasons for the formation of the bending structure of the flexible joint actuator were investigated.Under the premise of energy conservation in the actuator,the effects of the flexible frame size,the flexible frame thickness and the prestretching rate of the dielectric elastomer film on the bending angle of the actuator are investigated.Finally,its application to flexible manipulators is also investigated so as to have an overall optimisation of the actuator parameters.(4)A simple,adaptive and versatile two-finger soft gripper driven by a conical DEA is developed,consisting of a conical actuator,a front gripper and a force transfer mechanism.The output performance of the conical actuator was optimised by adjusting the geometry,preload and bias voltage of the conical actuator.The modified flexible manipulator takes advantage of the efficient displacement amplification(up to 9 times)of the designed force transfer mechanism to convert the input force in the vertical direction into a gripping force in the horizontal direction,taking advantage of the large displacement(i.e.high input force)of the conical actuator in the vertical direction.Thus,in addition to regular and hard objects,some small,irregular,soft or squeezable objects can be easily grasped by the retro-manipulator without sensors or complex controls,and it can grip objects up to 16 times its own weight.The work in this paper will provide guidance for the adaptive,highly reliable design of soft gripper.