Reverse Solution Method For Design Target–oriented Pneunet Soft Actuator Structures

Soft robots possess remarkable development potential in the fields of medical treatment,education,and rescue,owing to their high flexibility,excellent adaptability,and natural and safe interactivity.However,the highly nonlinear characteristics of hyperelastic materials present a significant challenge in the theoretical design of soft robots,leading to a dearth of relevant theoretical guidance.Consequently,the design of existing soft robots is typically based on empirical inspiration and repeated experimental verification and modification.In response,this study focuses on the Pneu Net structure and proposes a design goal-oriented reverse solution method for the Pneu Net soft actuator structure.The key research contents and conclusions are outlined below.(1)The Pneu Net soft actuator employs three popular silicone rubber materials,namely Ecoflex 00-30,Ecoflex 00-50,and Dragon Skin 30,as its base material.To obtain the hyperelastic constitutive model and its coefficients with the highest fitting degree for these materials,the uniaxial tensile test,in combination with the material evaluation function of ABAQUS,is utilized.Through this approach,the optimal hyperelastic constitutive model and coefficients for the three materials are determined.(2)Numerical simulation experiments on multiple groups of Pneu Net soft actuators are conducted using ABAQUS.Observing the deformation of the soft actuators during the simulation,a sub-structure analysis method is developed to analyze and summarize their force characteristics.Furthermore,since the models with high fitting degrees for the three silicone rubber materials are mainly Ogden and Yeoh models,theoretical models are established for these two models accordingly.(3)The manufacturing of the Pneu Net soft actuator is completed in this study using the lost-wax casting method.Furthermore,a device for measuring the bending angle is constructed and utilized to obtain experimental measurements of the bending angle.The bending angle calculated by the mathematical model is compared and analyzed with the experimental measurements.The results indicate that the mathematical model of the Pneu Net soft actuator developed in this study is valid when no balloon expansion effect is observed.(4)A design goal is proposed for a novel Pneu Net soft actuator in this study.The mathematical model established in this research is utilized to carry out the design calculation,resulting in the theoretical value of the air cavity wall thickness for the new actuator.Based on the allowable manufacturing errors,an appropriate value for the wall thickness is selected.The lost-wax casting method is used to fabricate the new actuator,which is then tested for bending angle.The measured bending angle deviates from the design target by only 0.27°,indicating that the accuracy of the goal-oriented inverse solution method for the Pneu Net actuator structure is validated.