| Summary: | 碩士 === 國立成功大學 === 造船及船舶機械工程學系 === 90 === A nonlinear system containing disturbances and uncertainties are concerned in thus study. The parameter variations in the nonlinear terms of the system and treated as “ gray numbers”, which are parts unknown. The nonlinear system will be linearlized first by means of the so-called “the feedback linearization” technique and then be formulated into the so called ”H∞ standard problem”, which can be controlled by an H∞-optimal controller. The system matrices in the linearized system are usually gray ones because of the presence of plant parameter variations and uncertainties. Due to the properties of an H∞-control law, the proposed gray H∞ controller is able to surpass the H∞-norm of the closed loop transfer function between the exogenous input (e.g., disturbances and uncertainties) and the controller outputs (e.g., tracking errors and control energies). Thus, the proposed controller is robust to plant uncertainties and disturbances. Furthermore, a nonlinear gray-H∞ controller is proposed in this reach by simplify recover the nonlinear form of the controller from the feedback linearization process. To ensure the closed – loop stability, a MIMO circle criterion is applied to analyze the allowable sectors of the nonlinear uncertainties. Finally, a nonlinear robot manipulator, which has uncertain loads, is used to attest the feasibility of the proposed controller.
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