Study On Applicability Of Modal Space Decoupled Controller For A Hydraulically Driven Stewart Platform

Hydraulically driven6-6Stewart platform is an important part of a flightsimulator, and what brings difficulty to the study on digging out the system’sapplication potential by improving control method is the strong coupling of thesystem’s kinematics and dynamics. Modal space decoupled control method is acontrol method based on the dynamic coupling compensation principle, which isonly fit to viscous proportional damping system. The research of its applicability innon-viscous proportional damping system is to broaden the range of its application.Besides, further study of dynamic coupling will also promote the development ofhydraulic control theory of multi-degree of freedom system.This paper first analyzes kinematics and dynamics of the system, consideringthe friction of active joints and passive joints, especially the friction of passivejoints which is used to ignore. A set of complete multi-rigid-body dynamic equationsof the system is obtained with Kane’s method. It also derives the transfer functionmodel of the hydraulic driven system. The overall dynamic model of the system isbuilt combining the driving system and motor system.Then the theoretical basis of modal decoupling controller design and theanalysis method of multi-DOF motion system are briefly introduced. The massmatrix and stiffness matrix of the system at neutral position are obtained, as well asthe numerical solution of the modal matrix. The relation between the dampingmatrix, mass matrix and stiffness matrix is calculated and analyzed.At last, the model of control system is built with MATLAB; the model ofhydraulic driving system is built with AMESim. Using MATLAB’s SimMechanicstoolbox to establish the dynamic model, the overall model of the system is built.The applicability of modal space decoupled controller in viscous and non-viscousdamping system is researched.