Research On Dynamic Characteristics Of The End Of Rigid Flexible Coupling Manipulator

Compared with the rigid manipulator,the flexible manipulator has the advantages of high load to weight ratio,low energy consumption,fast response and flexible operation.Therefore,flexible manipulator is more and more used in industry,medical,national defense,space and other fields.However,the flexible manipulator has the problems of inaccurate positioning and residual vibration.So it is necessary to study the dynamic characteristics of flexible manipulator and control the joint angle.In this paper,firstly,the dynamic model of single link flexible manipulator is established,and the dynamic model under two different deformation descriptions is compared,and the more appropriate dynamic model is selected for the next research.On this basis,the influence of different factors under different speeds on the dynamic characteristics of the single link flexible manipulator is analyzed,whether the nonlinear term is considered or not,and whether the gravity is considered or not.Then,a PD controller based on position loop is designed,and RBF neural network is used to control the joint angle.Then,the dynamic model of the rigid flexible coupling manipulator is established,and the influence of different factors on the dynamic characteristics of the rigid flexible coupling manipulator is analyzed.At last,it is verified and analyzed by experiments.The specific research contents are as follows:(1)The dynamic models of the single link flexible manipulator in the case of the secondary deformation and the univariate deformation are established respectively,and compared under different inputs.Firstly,the dynamic equations of the two cases are obtained by Lagrange equation and Hamilton principle.Then,the end deformation and input torque of the single link flexible manipulator are compared under step input,sine input and single bar calculation input.The similarities and differences between the two models are analyzed and one of the two models are selected.(2)The dynamic model of the univariate deformation is selected to analyze,and the influence of the length,bending stiffness and gravity on the dynamic characteristics of the single link flexible manipulator are studied.Firstly,the dynamic equation of a single link flexible manipulator under the univariate deformation is rewritten equivalently,and then the influence of the length and bending stiffness of the single link flexible manipulator on the enddeformation and input torque are analyzed respectively when the nonlinear term is considered or not at high speed and low speed.Next,a dynamic model considering gravity is established,and the influence of gravity on the input torque is analyzed.(3)A PD controller based on position loop is designed for the driving system of single link flexible manipulator.On this basis,RBF neural network is used to control the joint angle.Firstly,the transfer function of the driving system is obtained by Laplace transform of the dynamic equation of the single link flexible manipulator,and then the pole assignment method is used to carry out the pole assignment,so as to obtain the controller parameters.Then,the inner control loop with nonlinear compensation term is designed.On this basis,RBF neural network is used to approximate the uncertainty term in the system,so as to control the joint angle and reduce the error between the actual joint angle and the expected joint angle.(4)In the case of the univariate deformation,a rigid flexible coupling dynamic model is established,and the influence of different influencing factors on the dynamic characteristics of the rigid flexible coupling manipulator system is analyzed.Through the dynamic equation of the coupling of the modal coordinates of the first-order mode of the flexible manipulator,the input torque of driving the rigid manipulator and the input torque of driving the flexible manipulator,the relationship between the end deformation of the flexible manipulator,the magnitude of the input torque of driving the rigid manipulator and the peak frequency and amplitude of vibration,the magnitude of the input torque of driving the flexible manipulator and the peak frequency and amplitude of the vibration and the length of the rigid manipulator,the length of the flexible manipulator,the bending stiffness of the flexible manipulator,the end mass of the rigid manipulator is analyzed.(5)An experimental platform that can measure the acceleration at the end of the connecting rod,the motor angle,the connecting rod angle,and the input torque,the output torque is built,and the single link flexible manipulator is replaced by an aluminum plate for experiments.The piezoelectric acceleration sensor is used to measure the acceleration at the end of the connecting rod,the encoder is used to measure the connecting rod angle,and the tension sensor is used to measure the input torque and the output torque.The relationship between the dynamic characteristics of the single link flexible manipulator and the rotation speed,the length of the connecting rod and the bending stiffness is analyzed.The control effect of different proportional controller P and integral controller I is compared.The necessity of considering the gravity factor is verified.