A Study On Dynamic Modeling Of Large Cable-Driven Parallel Manipulator

This thesis takes the cable-driven parallel manipulator as the research object. Due to its characteristics of high efficiency, high load carrying capacity, high precision, small heavy-duty, compact structure, good dynamic performance and easy to control, the cable-driven parallel manipulator is widely applied in numbers of situations requiring high precision, high speed and high efficiency.It is necessary to establish the dynamic model of the cable-driven parallel manipulator when an analysis is made on it. The existing methods of modeling usually ignore the flexibility of the cable or take the cable as cable-strut element to simplify the process of modeling, as a result the movement of the manipulator is described inaccurately. So the existing methods of modeling have their limitations.In this thesis we study the method of modeling of the cable-driven parallel manipulator to get a better description of its movement. Taking the flexibility of the cable into consideration, this thesis studies two different methods of modeling. The first method establishes the dynamic functions of the system by using variational principle and Hamilton’s principle in terms of energy, and solves the dynamic functions by using Assumed Mode Method. The second method is Variable Length Finite Element Method, which establishes the dynamic functions by using absolute nodal coordinate formulation. The simulations of these two methods are conducted in the environment of MATLAB, and a comparison of their results is made. The results and comparison show that the Assumed Mode Method and the Variable Length Finite Element Method both have their own characteristics, and both can describe the movement of the cable-driven parallel manipulator well. Compared with Assumed Mode Method, a better simulation result can be gained by using Variable Length Finite Element Method.