Copyright © 2026 Authors retain the copyright of this article. This article is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

@article{184911,
        author = {PIDUGU  SHARMILA and B AMARENDRA REDDY},
        title = {Performance Evaluation of SMC Strategies along with DOB for Third-Order Uncertain Plants},
        journal = {International Journal of Innovative Research in Technology},
        year = {2025},
        volume = {12},
        number = {4},
        pages = {4625-4643},
        issn = {2349-6002},
        url = {https://ijirt.org/article?manuscript=184911},
        abstract = {This study proposes a systematic design and rigorous analysis of a Disturbance Observer (DOB) tailored for second and third-order interval plants. The developed framework focuses on real-time estimation and active compensation of external disturbances and inherent model uncertainties, ensuring robust performance across a range of system variations. The DOB was constructed using a nominal third-order model while accounting for parameter variations within defined intervals. By feeding the estimated disturbances back into the system, the method significantly enhances the robustness and stability even under substantial external disruptions. A conventional PID controller is designed in conjunction with the DOB to regulate plant dynamics, thereby improving performance under both nominal and disturbed conditions. To validate the efficacy of the proposed control strategy, comprehensive MATLAB simulations were performed under diverse disturbance conditions. These included standard profiles such as step, sinusoidal, square, sawtooth, and stair-generator signals. The simulation outcomes demonstrate the robustness and adaptability of the controller in accurately compensating for a wide spectrum of dynamic disturbances. Furthermore, a comprehensive comparative analysis was conducted involving four advanced control methodologies: PID control, SMC, Modified-SMC, and PID-Sur-SMC. These strategies were systematically evaluated on both second and third-order interval systems, as well as DC motor models, to assess their performance in terms of disturbance rejection, tracking fidelity, and robustness under parametric uncertainties. Stability analyses of the linear and nonlinear components are performed using Lyapunov’s direct method, whereas the Kharitonov polynomial approach is employed to guarantee robust stabilization across interval uncertainties. The findings of this study reveal that integrating the proposed Disturbance Observer (DOB) with PID control and advanced Sliding Mode Control (SMC) variants significantly enhances system performance. This hybrid approach delivers superior disturbance attenuation, faster transient response, and improved quiescent state accuracy contrasted with existing control techniques. Extensive simulation results affirm the robustness and reliability of the proposed methodologies, establishing a resilient and high-precision control framework well-suited for systems operating under substantial external disturbances and structural uncertainties.},
        keywords = {Low Pass Filter (LPF), Disturbance Observer (DOB), Sliding Mode Control (SMC), Modified Sliding Mode Control (M-SMC), Proportional-Integral-Derivative surface Sliding Mode Control (PID sur-SMC), Surface-Mounted Permanent Magnet Synchronous Motor (SPMSM)},
        month = {October},
        }