Study On Tension Characteristic And Dimensional Synthetic Design Of Cable Driven Parallel Manipulators With Large Span

As part of the Five-hundred meter Aperture Spherical radio Telescope (FAST) project, this paper aims at key issues of tension characteristic and dimensional synthetic design for cable driven parallel manipulators with large span.Considering the impact of the cable weight and elastic deformation, this paper works out the kinematic and statics modeling equations of cable driven parallel manipulator with large sapn based on three single cable modeling equations, including precise catenary equation, parabola equation and line equation. Then, the modeling errors of the simplified modeling equations are developed, and a modeling error compensate multinomial is presented for improving modeling accuracy. The six-cable driven parallel manipulator and its similarity model of FAST are introduced to prove the feasibility of the modeling and error compensation methods.Difference of maximum and mininmum tension , ration of maximum and mininmum tension , and their global indices and are presented for analyze the static characteristic for cable driven parallel manipulators with large span. This paper completes the error modeling, and uses a tension controllability generalized volume index TCGVI and its global index GTCGVI to study the tension characteristic in its allowed error space of a cable driven parallel manipulator with large span. All the analyses methods are simulated by the similarity model of the six-cable driven parallel manipulator of FAST.This paper fulfills the stiffness modeling of cable driven parallel manipulators with large span, and puts forward two stiffness characteristic indices, global stiffness index on a single direction and global change rate of stiffness on a single direction , for evaluating the stiiffess characteristic for a cable driven parallel manipulator with large span. A stiffness similarity model can be set up by adopting the Buckingham similarity theorem, and stiffness value can be calculated by stiffness experimental value. All the analyses and experiment methods are proved by a four-cable driven parallel manipulator. To study the dimensional synthetic design method of cable driven parallel manipulators with large span, optimized deign functions are presented to reflect the influence of the dimensional parameters on mechanism characteristics. This paper adopts the tension and stiffness characteristics indices to set up optimized deign functions, and give a set of optimized dimensional parameters of the six-cable driven parallel manipulator by synthetic evaluation analysis.This paper sets up a 1:15 kinematic similarity model of the six-cable driven parallel manipulator of FAST. By adopting the simplified modeling equations to complete the control algorithm, motion accuracy and tension experiments are done on the similarity model. The experiment result confirms the study methods in this paper.