Parametic Modeling And Modal Experiment Of CDPM

Cable Driven Parallel Mechanism(CDPM)is a new type of mechanism that is developed based on the traditional rigid rod parallel mechanism.Compared with the rigid rod Parallel Mechanism,CDPM has the advantages of high speed,small inertia,large working space,etc.However,Due to the cable characteristics of one-way load bearing,overhang with its gravity and mass variability with dynamic loads,the modelling,dynamic response analysis and dynamic control of CDPM are much more complex than traditional rigid rod parallel mechanism.In the normal system prototype modeling,a large amount of time is needed for model reconstruction when the mechanism parameter is changed.As the modeling of CDPM prototype and finite element model is much more difficult than rigid rod parallel mechanism,the efficiency of product design will be greatly affected if the traditional modeling method is used.In this paper,the parametric modeling methods of the flexible cable and the cable driven mechanism,the constrained modal testing are studiedbased on four-cable 3-DOF CDPM.The dynamic model of four-cable 3-DOF CDPM is constructed and the theoretical modeling and analysis of inverse kinematic are derived.Based on Adams software,the equivalent kinematics simulation model is established,and the correctness of the theoretical kinematic analysis of the mechanism is verified by the simulation results.Furthermore,the parametric kinematics model of the CDPM,with which the mechanism parameters are optimized,is established based on Adams software.Moreover,the feasibility and effectiveness of the parametric dynamic modelingmethod of the cable model are verified by the establishment of a dynamic parametric model of two hinged free cable.The finite element parametric model of four-cable 3-DOF CDPM is developed especially for the geometric modeling,load applying and result output of the flexible cable.The finite element parametric model lays the foundation for a further modal experiment.The cable force of finite element model and actual work is confirmed based on the principle of the vibration measurement method.Thus the theoretical modal solution is solved by the finite element parametric model.Base on LMS testing system and modal analysis theory,the modal of moving platform in constrained state can be analyzed.The natural frequency andvibration mode of the platform are determined.Compared with the theoretical andexperimental results,the validity of the finite parametric model is verified.