Determination of realistic uncertainty bounds for the Stewart Platform with payload dynamics

Robust Control of Stewart Platform has been successfully demonstrated by various authors [8-12]. The work done so far is based on the assumption that the bounds on uncertainty are known and the chosen reachability gains are greater than these bounds. This assumption can only be justified if those bounds could be quantified, which is not the case in the existing approaches. The problem gets severe when the controller has to compete against the variations in payload, especially when the payload is asymmetric. This paper addresses such uncertainties. The novelty of the paper lies in the extension of existing nonlinear model to include asymmetric payloads and quantification of uncertainties arising from the use of a variety of asymmetric payloads. The actual Moments of Inertia (MOI) of the Stewart Platform with asymmetric payload are computed and used to find worst case uncertainty bounds. The control performance of the proposed algorithm is verified by computer simulations. These simulations show that the system follows the desired trajectory and errors converge to equilibrium points efficiently.