Research Output
Articles
Kim, H.,
Shim, H.,
Jo, N.H.,
Ataei, M.,
Park, G. Publication Date: 2025
IEEE Transactions on Industrial Electronics (02780046)
This article presents a new structure of a sliding mode disturbance observer (SM-DOB) for handling model uncertainty and unmodeled disturbances. The proposed SM-DOB is composed of two key components. First, a Levant’s differentiator is used to estimate the high-order time derivatives of the output. To satisfy the conditions required for the effective operation of Levant’s differentiator, we employ an integral SM technique so that on the sliding surface, the real plant’s dynamics are substituted with the nominal dynamics. With this structure, the proposed SM-DOB can achieve robust disturbance rejection and recover nominal performance in finite time. The stability and the finite time convergence of the proposed SM-DOB are rigorously proved by the Lyapunov stability method. Finally, to show the superiority and verify the validity of the proposed SM-DOB, we conduct both numerical simulations and laboratory experiments with brushless dc (BLDC) motor drives. It is observed that the proposed SM-DOB guarantees satisfactory performance in rejecting both input disturbance and plant uncertainty while remaining robust in the presence of noisy measurement. © 1982-2012 IEEE.
Publication Date: 2025
IFAC-PapersOnLine (24058963)59(10)pp. 697-702
This research proposes a three-channel control scheme to improve transparency and stability in nonlinear bilateral telerobotic systems. The control framework emphasizes position tracking and synchronization, with an unknown input observer estimating the external force exchanged between the environment and the slave robot. This estimated force signal is incorporated into the master robot's controller to achieve the design objectives. Specifically, the control approach addresses three primary goals: (1) position tracking and synchronization; (2) enhanced transparency through accurate force refection; and (3) stability analysis of the telerobotic system. The system architecture, structured as a three-channel bidirectional design, leverages the observer-based control law to ensure that position tracking errors remain stable. Ultimately, the performance of the proposed control scheme is validated on a nonlinear bilateral telerobotic system, demonstrating its potential to enhance both stability and transparency in real-world applications. Copyright © 2025 The Authors.
Publication Date: 2025
ISA Transactions (00190578)164pp. 1-13
Data-driven control methods in the frequency domain commonly require the determination of controller structure. Relaxing such restriction in the proposed algorithm, the controller design is transformed into an optimization problem, based on the υ-gap Metric criterion. By defining a desired stability margin and the desired frequency response of the controller, a criterion is determined to characterize a family of controllers. Therefore, a model free procedure is proposed to determine a family of controllers, by taking the plant frequency response and the desired stability margin. On the other hand, by adopting a new index, presented in this paper, the designer can determine the optimal controller, based on the implementation conditions. Another advantage of the proposed method is its applicability to uncertain Multi-Input Multi-Output (MIMO) systems. The loop performance in the presented algorithm can be also enhanced by appropriate selection of weighting matrices in a loop shaping procedure. Two examples are also presented to demonstrate the effectiveness of the method for multi-variable non-square uncertain systems, including a practical example of a purely delayed system. © 2025 ISA
