Mechanical Modeling Of The Dielectric Elastomer Multilayer Actuator And Design Of The Soft Robot System

Robots are widely used in the manufacturing industry.Traditional robots composed of rigid materials possess the advantages of sufficient power and high precision.But they are challenged in flexibility and human affinity,when working in complex environments and assisting medical rehabilitation,for instance.The rise of soft robots,whose bodies mainly consist of soft materials that withstand large deformation,provides motivation to tackle such challenges.They enjoy the properties of decent flexibility and powerful impact resistance.Different from robots driven by rigid structures like the motor-transmission system,soft robots are powered by soft active materials similar to "artificial muscles" that can deform under external stimulation and fulfill system functions.Dielectric elastomer(DE),as a typical electroactive soft material,is popular for its large actuation strain,fast response and high energy density,which is expected to provide support for the development of high-performance soft robots and their applications in the field of aerospace,deep-sea exploration and medical rehabilitation.How to construct a soft actuation structure with efficient compliant deformation and stable control from analyzing the electromechanical deformation mechanism of DE,hence achieving a reliable operation of the robot system in the complex task environment,is the key issue in studying DE and DE soft robot system.Focusing on this key issue,the main contents and conclusions of this paper are described as follows:(1)For the modeling of the soft actuation structure,an electromechanical model of dielectric elastomer multilayer bending structures is proposed,which can be used to calculate the deformation of DE multilayer structure and assess how the load parameters,material parameters and geometric parameters affect the bending.In addition,under certain conditions,the model can be simplified to obtain an explicit function to predict the bending deformation during actuation.The simplified model helps to quickly estimate the magnitude of actuation deformation for this kind of DE multilayer structure.(2)For the construction and control of the soft actuation structure,DE multilayer bending actuators are developed through anisotropic DE membranes,which the actuation voltage of is reduced to hundreds of volts and can achieve large bending deformation without pre-stretch.Subsequent dynamic modeling of the bending actuators is performed to analyze the nonlinear behavior of their large bending deformation,supporting the design of model-based adaptive control of the actuators which can compensate for the model uncertainty and nonlinearity of the actuation.(3)For the fabrication and application of actuators of complex multilayer structures,a process to fabricate DE actuators integrating with fused deposition modeling(FDM)type 3D printing is proposed,which can directly generate elastic frames with complex shapes and integrate them onto pre-stretched DE membranes without any extra adhesive.This integration process enables rapid iteration between structural designs of complex actuators.Two kinds of electroactive soft actuators are designed and fabricated from the proposed fabrication process,which is a soft gripper and a soft robot fish,and finite element analyses and experiments are implemented on them.(4)For deep-sea applications,an electroactive self-powered soft robotic fish adapted to the extreme hydrostatic pressure is designed.By characterizing the performance of DEs under low temperature and high pressure,we verify the actuation capability of the DE material in extreme deep-sea conditions;A micro pressure-tolerant electronic module is developed,which can output a steady voltage required by the DE actuators in the high hydrostatic-pressure environment;Soft flapping fins are attached to the DE multilayer actuators to complete the actuation system,which,along with the embedded electronics,are integrated to build the soft robot.Validated by experiments in the simulated deep-sea environment,the designed self-powered soft robot is successful in a field test in the Mariana Trench to a depth of 10,900 m and swims in the South China Sea at a depth of 3,224 m.