Minimum Energy Dielectric Soft Joint: Design Modeling And Experiment

Human are always dreaming to create soft robots to mimic creature. The key component for mimicking is a soft actuator with higher power density and conversion efficiency like muscle. Under such background, the soft actuator attracted much attention as a frontier. Among different kinds of soft actuators, the dielectric elastomer actuator was considered as the best candidate for artificial muscle for demonstrating actuated strains of over 200%, estimated energy densities of over 3J/g, and energy conversion efficiency of 60%-90%. The DEMES(Dielectric Elastomer Minimum Energy Structures) was a new kind of dielectric elastomer actuator which specialized in flexible deformation. DEMES realized the 3D deformation which the energy released from the contracting elastomer is partially stored as bending energy in a flexible frame. However, the basic theory of DEMES soft joint was still in developing. In this paper, elaborate analysis and experimental verification of DEMES with static model and dynamic model were presented, hoping to describe the characteristic of DEMES and provide a reference for design and application.In the matter of the deformation principle and statics, the mechanical property of DEMES and the influence of critical parameter b to the electromechanical performance were analyzed. The mathematical expression of output torque, natural frequency, rotational inertia and stiffness were given. Also, the design criterion of DEMES was proposed according to the expression. Furtherly, a new design concept of DEMES was presented for improving the output torque of the joint.It is hard to set up real mechanics model because of complex morphology of deformed dielectric elastomer. In this paper, kinematics equations of electrified and out-of-electrified DEMES soft joint were given based on equivalent stiffness and coefficient. The experiment data was fitted with least square method and the numerical solution of the kinematics equations were solved with Matlab. Subsequently, the error analysis was given according to the result.Also, the fabrication process of DEMES soft joint and parameter testing were studied in this paper. To verify the veracity of static model and dynamic model, the confirmatory experiment of critical parameter b, natural frequency,new design concept,the damping and the moment of film and flexible frame of electrified and out-of-electrified DEMES soft joint were implemented.