Dynamic Analysis And Vibration Control Of Four-Cable-Driven Parallel Manipulators Vibration Attenuation Control

The object of this thesis is four-cable-driven parallel manipulators.Because the cable-driven parallel manipulators possess several merits,such as low inertia,low manufacturing costs and fast response speed.And it has been widely used in deep-sea salvage and rescue,large-radio telescope and other national defense industry and production field.In the kinematics analysis of the four-cable-driven parallel manipulators system,ignoring the elastic deformation of the flexible cable will lead to a large error in the kinematics analysis of the robot system,and can't describe the robot system accurately.At the same time,when the four-cable-driven parallel manipulators system is moving in the working space,the flexible cable will inevitably produce vibration,which leads to the vibration of the actuator,which causes the low frequency vibration of the whole robot system,and directly affects the motion accuracy of the terminal actuator when working.This paper mainly studies the kinematics and dynamics analysis of the four-cable-driven parallel manipulators system and puts forward a vibration control strategy to control the vibration of the system.The specific work is as follows:1.First of all,in this paper analyzed the model structure of the four-cable-driven parallel manipulators system,then solved and discuss its Jacobian matrix of the system.Under consideration of elastic deformation of the flexible cable,solve the kinematics inverse solution of the robot system.Solving the kinematic positive solution of the system by the principle of minimum potential energy and Newton iteration method.Finally,the simulation was carried out with Mathematica software,and compared with the results obtained by using ANSYS analysis.2.In consideration of flexible cable elastic deformation and its deadweight,the model of flexible cable is simplified and the modal function is assumed to be trigonometric functions by simulating free vibration of flexible cable.By establishing a local coordinate system on each flexible cable,establish the position coordinates of any point in the robot structure.The assumption mode method is used to solve the system dynamic equation,and the numerical simulation in MATLAB software verifies the feasibility of the theory.Based on the above,this paper discusses the influence of the assumption mode method on the results of neglecting the first-order and second-order derivatives of the flexible cable coordinate transformation matrix.3.By simulating the small-amplitude vibration of flexible cable under the condition of elastic deformation of flexible cable,the finite element method is used to establish the dynamic model of the four-cable-driven parallel manipulators system.The numerical simulation of the dynamics is performed with the help of MATLAB,and compared with the results obtained by the numerical simulation of the assumed modal method.A vibration control strategy for the four-cable-driven parallel manipulators system is proposed,which is a parallel control strategy of the trajectory tracking controller and the vibration attenuation controller.The control strategy proposed in this paper is applied to the finite element method and the assumption mode method.The control strategy presented in this paper is applied to the numerical simulation of the finite element method dynamic model,the effectiveness of the vibration control is discussed,and the effectiveness of the constant gain matrix and the time-varying gain matrix on the control effect is studied.The robot system is often disturbed in the practical work,so the numerical simulation is carried out under the aid of software,and the effect of vibration control strategy on the vibration control of the robot system is discussed when the system is disturbed by the initial position error and the external disturbance respectively.