Supervision and Control Strategies of a 6-DOF Parallel Manipulator Using a Mechatronic Approach

Currently, the Stewart Platform is used in different engineering applications (machine tool technology, underwater research, entertainment, medical applications surgery, and others) due to its low mechatronic cost implementation as an alternative to conventional robots. The current trend of using parallel manipulators has created the need for developing open supervision and control architectures. This chapter presents the mathematical analysis, simulation, supervision and control implementation of a six degree of freedom (DOF) parallel manipulator known as the Stewart platform. The related studies are critically examined to ascertain the research trends in the field. An analytical study of the kinematics, dynamics and control of this manipulator covers the derivation of closed form expressions for the inverse Jacobian matrix of the mechanism and its time derivative, the evaluation of a numerical iterative scheme for forward kinematics on-line solving, the effects of various configurations of the unpowered joints due to angular velocities and accelerations of the links, and finally the Newton-Euler formulation for deriving the rigid body dynamic equations. The contents of this chapter are organized as follows: • Section II presents the features of a Stewart Platform manipulator, describing its spatial motion and applications. • Section III covers the mathematical description, with the kinematics and dynamics modelling, and the actuator control using a mechatronic prototyping approach. • Section IV details the control structure, and compares two different control strategies: the PID joint control structure and the Generalized Predictive Control (GPC). Both controllers structured in the polynomial RST form, as a generic framework for numerical control laws satisfying open architecture requirements. • Section V describes the supervision and control architecture, particularly the spatial tracking error is analyzed for both controllers.