| Traditional robots have high rigidity and high precision and have been widely used in many fields such as industry,service,medical treatment,and special work.However,high structural stiffness also limits the adaptability of robots to the environment.The soft robot is made of flexible materials,and it is easy to achieve continuous deformation.In theory,it has unlimited passive freedom and can change its shape according to the surrounding environment.Contact with the environment can improve the adaptability of the soft robot,and effectively play the compliant characteristics of the soft manipulator.At the same time,relying on contact with the environment can also obtain a larger workspace and end stability.However,the environmental contact increases the distributed load of the soft robot,which brings great difficulties to the modeling and control of the soft robot.Therefore,the dynamic modeling of the soft robot and the motion analysis under the environmental contact state is very important.In this thesis,the coupling between the flexible hydraulic muscles was analyzed and the internal coupling statics model of the soft hydraulic manipulator was derived.Secondly,the traditional variable curvature model was improved,and the discrete elements were divided into two parts at the constraint points.The dynamics model of the soft manipulator was established by the Newton-Euler recursion method,and the attitude prediction problem of the soft manipulator in the constrained environment was solved.Finally,a six-degree-of-freedom hydraulic drive test system for the soft manipulator was built,and the proposed mathematical model was verified.The main contents of this thesis are as follows:(1)The internal coupling influence analysis was carried out on the single-segment soft manipulator.The three driving units of the single-segment soft actuator were analyzed independently,and the forces of different driving units were considered respectively.The internal coupling action model was established from the perspective of the constant curvature of the driving unit and equilibrium of top constraints.(2)Establish kinematics and dynamics models of the soft manipulators under a constraint environment.Under the premise of the piecewise constant curvature model,when the soft manipulator interacted with the environment,it was further divided into two arcs with continuous but different curvature based on the contact point between the external environment and the manipulator.Combined with the constraint of the position of the contact point of the environment,the static posture of the soft manipulator was obtained.Based on Newton-Euler dynamics,the motion parameters of the discrete soft manipulator were obtained by recursion from the inside out,and then the forces of the discrete soft manipulator were obtained by recursion from the outside in.Finally,the general equations of dynamics are obtained.(3)An experimental system was built for the soft manipulator,and the soft manipulator was driven according to the expected target through the hydraulic drive system.At the same time,the Kinect sensor was used to capture the attitude of the soft manipulator,which was compared with the simulation results to verify the accuracy of the model. |
