Study of sliding mode control for stewart platform based on simplified dynamic model

Abstract

Stewart mechanism is widely used in industry. To study the control of Stewart mechanism, hydraulic Stewart platform was used as plant. Controller was designed according to dynamic model, so local closed-loop control system was to be built. Coefficient matrices of dynamic equation of Stewart platform can only be known by measuring real-time pose of platform and doing real-time calculation, which makes application complicated. Therefore dynamic model was transformed, and one operating point was defined as nominal operating point, where coefficient matrices of dynamic equation were constant. Sliding mode controller was designed with simplified dynamic model, and reaching condition of sliding mode was given in the entire workspace of platform. Hence real-time pose measure is avoided and calculation is reduced. Simulation and experiments show that system performance of trajectory tracking with payload is improved by use of the proposed controller.