Dynamics Study Of Cable Driven Parallel Robot For Ship Model Support Of Resistance Test

In this paper,the Cable Driven Parallel Robot used in ship model support and resistance test in towing pool is taken as the research object.The over-restraint type of Cable Driven Parallel Robot is analyzed theoretically and calculated numerically.Firstly,based on the geometric constraints and coordinate change rules of the mechanism,the inverse kinematic position and velocity equations of the mechanism are established by closed vector method and vector derivation.Then the dynamic equation is established by Newton Euler equation.Based on the dynamic equation,the method of measuring the resistance of ship model by mechanism is proposed.Secondly,based on the model of solution of non-homogeneous linear equations,the distribution optimization of tension solution of inverse dynamics is transformed into the selection of points on convex set of tension of rope,and a fast algorithm of vertex of convex set is given(calculation time is reduced to 44.35%of ergodic algorithm).Then,the tension of cable is distributed non-iteratively on finite convex set vertices and gravity center,and the whole calculation time of tension is reduced to linear gauge.Planning,quadratic programming and convex optimization are 25.75%,9.54%and 0.42%.The continuity of tension solutions of several point-to-point trajectory planning methods is analyzed.The numerical simulation shows that the continuity of tension depends mainly on the smoothness of acceleration change on the trajectory.In the process of solving cable tension by inverse dynamics,the judgment of feasible workspace of cable tension is changed into the judgment rule of whether the vertex of tension convex set is empty set.The judgment speed of this rule is obviously improved compared with the judgment of projection balance of reduced dimension.Based on this rule,the acceleration performance of measuring cable driving tension in tension feasible translational workspace is analyzed.The results show that the moving platform The acceleration performance can be significantly improved at the center of the horizontal plane of the rack.Then the numerical simulation of the static stiffness and dynamic stiffness of different cable tension distribution points,different positions and different trajectories at the same starting and ending points is carried out.The simulation results show that when the cable tension is far less than the stiffness of the driving chain,the stiffness performance is mainly determined by the position of the mobile platform;when the cable tension value reaches about 10%or more of the stiffness of the driving chain,the cable tension is increased.Force can obviously improve the stiffness of the mechanism.Reasonable planning of motion path,acceleration and distribution of rope tension can significantly improve stifness.Finally,the validity of the kinematics dynamics,stiffness matrix and resistance test model of the mechanism is verified by the test of the experimental prototype.