Abstract
For a class of multi-input multi-output nonlinear systems, a disturbance observer-based control is proposed to solve the tracking problem in the presence of mismatched disturbances. By designing a novel compensation gain matrix, the disturbances can be removed from the output channel completely as well as retaining the nominal performance. Compared with the state of the art, the gain matrix reduces to be constant; therefore, the complexity of the controller is simplified greatly. This method is applied to the control of hypersonic flight vehicles to demonstrate its effectiveness.
Highlights
In modern practical control systems, unexpected disturbances occur inevitably due to the external disturbances, unmodelled dynamics and parameter perturbations.[1,2,3]
Considering hypersonic flight vehicles (HFVs) for example, the mismatched disturbances caused by the dramatic changes in flight environments may influence the states directly.[9]
In the study by Zheng et al.,[10] a robust tracking controller was proposed for multi-input multi-output (MIMO) nonlinear systems using a variable structure control approach with the mismatched disturbances
Summary
In modern practical control systems, unexpected disturbances occur inevitably due to the external disturbances, unmodelled dynamics and parameter perturbations.[1,2,3] Efficient control techniques have been extensively investigated in the literature, such as H2 control,[4] H1 control,[5] sliding control,[6] adaptive control[7,8] and so on. In the study by Zheng et al.,[10] a robust tracking controller was proposed for multi-input multi-output (MIMO) nonlinear systems using a variable structure control approach with the mismatched disturbances. Inspired by the previous works, a tracking controller is proposed to counteract the mismatched disturbances for feedback linearizable nonlinear systems. Suppose that the disturbance d is bounded, the disturbance estimation error system of (5) is locally input-to-state stable, if the appropriate observer gain lðxÞ can be chosen, such that e_ðtÞ þ lðxÞqðxÞeðtÞ 1⁄4 0 is asymptotically stable for all x 2 Rn. In this article, we propose an output tracking control scheme for equation (1) in the presence of the mismatched disturbances via feedback linearization and nonlinear disturbance observer. The proposed tracking control scheme for system (1) will compensate for the mismatched disturbances in the output channel by designing a proper gain matrix. Hi À hid 1⁄4 Ciði À hidÞ where ei 1⁄4 1⁄2d^i1 À d1i d^i2 À d2i Á Á Á d^iri À drii T ; 1⁄2hid h_id Á Á Á hid ðriÀ1ÞT ; hid 1⁄4
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