Modal space decoupled controller for hydraulically driven six degree of freedom parallel robot

This paper proposes a modal space decoupling controller for the highly coupled six degrees of freedom parallel robot. It is based on singular value decomposition to the properties of the joint space inverse mass matrix, using an orthogonal unitary matrix. The method moreover, maps the control and feedback variables from the joint space to the decoupled modal space. Using this method, the highly coupled six-input-six-output dynamics of the parallel robot was transformed into six independent single inputs, single output one degree of freedom hydraulically driven mechanical system. The simulation result shows that the controller improved the trajectory performance more than the conventional PID controller in all DOF and eliminated the dynamic coupling effects.