A disturbance observer (DOB) has been widely employed in industrial field due to its simplicity and effectiveness in disturbance rejection. This paper focuses on systematic bandwidth-maximized DOB design by frequency response data-based convex optimization. The transformation process from original non-convex optimization to convex optimization has been formulated. Simulation results have verified the feasibility and generality of the proposal and shown that the designed DOB is able to achieve

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... od disturbance rejection performance. A general derivation process from non-convex constraints to convex constraints in DOB design has been developed. An iterative convex optimization process is established to solve the problem. 3. The requirement for the nominal plant and the damping factor of the Q filter have been mitigated compared with [16] . The proposed method is versatile for both minimum phase and non-minimum phase plants. The order of the