Analysis of coupling effects on hydraulic controlled 6 degrees of freedom parallel manipulator using joint space inverse mass matrix

This paper presents an analysis of the coupling effects between degrees of freedom of a hydraulic controlled six DOF parallel manipulator. Based on the singular value decomposition to the properties of its joint space inverse mass matrix, the method is put forward to analyze coupling effects between degrees of freedom using a transformation matrix, the product of transposed Jacobian matrix and an orthogonal unitary matrix, of which each element represents decoupled modal space coordinates with respect to physical task space frame. The simulation results in frequency domain prove the theoretical analysis right. The analysis will provide useful information to mechanism and controller designer, to asses from concept the coupling effects between DOF in respect of the requirement for a particular application and also for the study on decoupling control strategies.