Robustified GPC controller based on H∞ robust control for an hydraulic actuator
This paper proposes the robustification method of primary generalized predictive control GPC for a hydraulic actuator, which is previously modeled by an uncertain plant. Three-step procedures should be followed for robustification: First, the primary GPC controller based on nominal plant is designed to ensure a better tracking dynamic of the closed-loop system. Second, the Q-parameter transfer function is determined from solving the weighted-mixed sensitivity problem using the two Riccati equations where the uncertainty plant and neglected dynamics are taken into account. Finally, the Youla parameterization combines the primary GPC controller and Q-parameter to design the robustified GPC controller which enhances the trade-off robustness of primary GPC controller without changing its better tracking dynamic. To validate the effectiveness of the proposed robustification, the hydraulic actuator, which presents a realistic process, is controlled by both primary and robustified GPC controllers where their simulation results are compared in time and frequency domains by those given by the H∞ controller.
KeywordsH∞ control Hydraulic actuators Predictive control Robust control Two-term control
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