Motion control of a hydraulic Stewart platform with computed force feedback

Abstract On a Stewart platform with six hydraulic links, we mount three gyroscopes to measure the angular motion rates of its upper platform. Using these rate signals and the link lengths measured by LVDTs, we compute the orientation and position of the upper platform, as well as the static force acting on each link. These forces are put into a dynamic model of the hydraulic links based on which we determine the feedback gains for controlling the link lengths. Experiments on the platform with an unbalanced payload show that utilizing gains determined this way generates better results than utilizing a constant gain for all links.