Yanzhi Zhao, Hongnian Yu, Jie Zhang, Jiantao Yang, and Tieshi Zhao
Stabilized platform, parallel mechanism, extended state observer,sliding mode control, screw theory
This paper proposes a new control scheme of a stabilized platform with a 6-revolution universal spherical (6-RUS) parallel mechanism in non-inertial. A kinematics model of the stabilized platform with a 6-RUS parallel mechanism is developed using the screw theory which is a convenient way to analyse the velocity and acceleration of the whole rigid-body rather than a point on the body. Its dynamics model in a non-inertial frame is derived using the Newton– Euler linear–bilinear equation and virtual work principle which can simplify the dynamic modelling. Normally, a stabilized platform is a typical uncertain system due to the disturbance of the movements of the ship, parameter uncertainty, imprecision of the dynamic model and friction. To overcome the uncertainty, a sliding mode control (SMC) strategy with an extended state observer (ESO) is developed to control the stabilized platform. Simulation study of the platform is conducted using MATLAB and ADAMS. Compared with the computed torque control, the SMC with ESO in workspace achieves better performance in the control of the stabilized platform.
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