Abstract

In this paper, workspace analysis and control of a Stewart platform mounted on a moving vehicle are presented. In a medical room of a hospital ship, the rotation and vertical translation of the floor must be properly isolated from the wave-induced motion of the ship. On a moving vehicle, when a sensitive equipment is transported or a manipulator is utilized to perform precise positioning tasks, it becomes essential to isolate them from undesirable motion of the vehicle. For development of a motion stabilizer, which isolates a manipulator from undesirable ship or vehicle motion, we present a nonlinear model predictive control of a six degrees-of-freedom, base-moving Stewart platform. Firstly, the workspace analysis is performed considering kinematic and joint constrains. The boundary of the workspace is searched by numerically solving an optimization problem. Then, to obtain the future motion of the base plate of a Stewart platform caused by a ship or a moving vehicle, we employ an auto regressive moving average model which forecasts future behavior based on past behavior. Finally, nonlinear model predictive control low is adopted for a base-moving Stewart platform. In order to assess the performance of the proposed method, numerical simulations are presented.