Control and Systems Engineering, Modeling and Simulation
19
Scopus Publications
Scopus Publications
Indirect IFO-TID controller design for process control using shifted relay feedback control K. Gnaneshwar, Pushkar Prakash Arya, Rishika Trivedi, Prabin Kumar Padhy International Journal of Systems Science, 2026 The relay feedback approach is used to identify the real-time process dynamics and controller design based on limit cycle data. An inaccurate estimation of limit cycle parameters leads to erroneous process dynamics identification and hence the controller design. To improve accuracy, this work proposes a shifted relay technique to accurately estimate the limit cycle parameters and then an indirect fractional-order tilted integral derivative (IFO-TID) controller designed based on the estimated limit cycle parameters. The proposed shifted relay method provides flexibility to accurately estimate the limit cycle parameters with a single shifted parameter. A simulation study is carried out to implement the proposed shifted relay technique and then the results are experimentally validated on the four-tank level control system. Its superiority is shown over existing state-of-the-art techniques regarding accuracy under nominal and parametric analyses. Further, the proposed IFO-TID controller performance is compared with some of the existing methods, and it is observed that the proposed methodology is better in robustness and stability.
A frequency domain fractional order tilted integral derivative controller design for fractional order time delay processes Gnaneshwar K, Rishika Trivedi, Sudeep Sharma, Prabin Kumar Padhy Asian Journal of Control, 2025 In real‐time processes, time delays are inherent due to various factors, such as delays in volume, mass, and information transfer, leading to a deterioration in process performance and stability. Therefore, this paper proposes a fractional‐order tilted integral derivative (TID) controller design for stable and unstable fractional‐order processes with time delay, where the optimal controller parameters are designed using a deterministic approach. An inner loop controller is designed using stability analysis and a graphical approach for unstable fractional‐order time delay processes. The proposed approach offers flexibility and fine‐tuning in designing the controller for a specific application. A systematic reference to the disturbance ratio is carried out to assess the disturbance handling capacity of the proposed controller. It shows the sensitivity of the designed controller against disturbances in the frequency spectrum graphically. Numerous performance indices and time‐domain parameters are computed and compared with state‐of‐the‐art techniques to analyze the efficacy. Furthermore, it is validated on the experimental setup of a four‐tank system. Simulation and experimental results demonstrate that the proposed approach outperforms recent techniques in terms of process control and disturbance rejection.
Maximum Sensitivity Based Fractional Order PI-PD Controller for Second Order Time Delay Systems Rishika Trivedi, Bharat Verma, Prabin Kumar Padhy 5th IEEE International Conference on Sustainable Energy and Future Electric Transportation Sefet 2025, 2025 In this paper, a novel design approach for tuning of PI<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ</sup>−PD<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">µ</sup> controller is proposed. The proposed method uses maximum sensitivity and characteristic equation as the major design criteria to ensure the robustness as well as the stability of the system. The controller parameters are designed using characteristic equations, and the fractional-order λ and μ require the involvement of maximum sensitivity in the design procedure. The generalized equations are proposed for both stable and unstable processes. PI<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ</sup> − PD<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</sup> controller structure is used where PD<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">µ</sup> controller stabilizes the system and PI<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ</sup> controller improves the set point tracking of the system. Therefore, characteristic equations give the idea of the stability of the system. In contrast, Maximum Sensitivity is employed for robust control of process variations and model uncertainty. The effectiveness of the controller is verified by a example, and an experimental verification on a conical tank system. Simulation and experimental results evidenced that the proposed methodology's performance is better than the state-of-the-art techniques.
Hybrid Fractional-order PI-PD Controller Design with Indirect Design Approach Rishika Trivedi, Bharat Verma, Prabin Kumar Padhy 2025 IEEE 1st International Conference on Smart and Sustainable Developments in Electrical Engineering Ssdee 2025, 2025 In this article, a Hybrid controller structure with fractional order Proportional Integral (PI) and Integer order Proportional-Derivative (PD) controller is proposed (FOPI-PD) for stable and unstable first-order processes. The proposed controller structure consists of a Feed-forward fractional order PI controller and Feedback integer order PD controller. The Proportional Derivative controller in feedback gives a better regulatory response as compared to the Feed-forward PD controller; and the fractional-order PI Controller in feed-forward helps to achieve the better Servo response. Analytical tuning rules are proposed for the FOPI-PD controller with the help of Gain and Phase Margin analysis. After that, the proposed controller is further fine-tuned with the Fractional Indirect Design approach-2 to mitigate the mathematical approximation errors and improve the performance of the proposed controller. Additionally, it is shown that the robustness of the FOPI-PD controller can be adjusted with a single variable in a given range. The proposed controller is validated with the help of the MATLAB simulation examples on the First-order Stable and Unstable processes.
Novel Rational Approximated Fractional Order Lead Compensator Rishika Trivedi, Prabin Kumar Padhy IETE Journal of Research, 2023 This paper proposes a simplified and analytical method for designing fractional order lead compensator (FOLC). In the proposed method, the structure of fractional order lead compensator considered is more generalized. The fractional operator of the FOLC is approximated to its equivalent rational form using binomial expansion to lower the computation complexity of the designing approach. Then, steady-state gain, gain cross over frequency and phase margin are used as the design specifications of the FOLC. The proposed method also considers the magnitude and phase of the plant to be controlled. Phase margin criteria ensure the stability of the designed compensator. The compensator is designed strictly adhering to gain and phase margin criteria. The proposed methodology is validated with four different illustrative examples through simulation. Integral absolute error (IAE) and integral square error (ISE) are considered as the performance indices. The simulation results demonstrate that the proposed scheme gives a better transient response, IAE, and ISE as compared to the existing FOLC design techniques.
Robust design of fractional order IMC controller for fractional order processes with time delay Kurnam Gnaneshwar, Rishika Trivedi, Prabin Kumar Padhy International Journal of Numerical Modelling Electronic Networks Devices and Fields, 2022 This article presents a novel approach to the robust design of fractional order IMC controller for the fractional‐order (FO) plus time delay processes. The proposed methodology provides the flexibility to adjust the controller performance based on the application requirement using a single parameter. Also, it does not require any external filter. Thus, it ensures a better response over existing methods. A mathematical analysis is provided to select the tuning parameter to obtain the optimal solution. The effectiveness of the proposed methodology is measured for different FO processes with time delay using time‐domain specifications, performance indices and frequency domain parameters. Load disturbance analysis under various disturbances and robust analysis under uncertainty in process gain in the presence of the disturbances is carried out to study the sensitivity and robustness of the controller. The performance parameters are estimated in both analyses and compared with the different approaches available in the literature.
Design of Indirect Fractional Order IMC Controller for Fractional Order Processes Rishika Trivedi, Prabin Kumar Padhy IEEE Transactions on Circuits and Systems II Express Briefs, 2021 In this brief, indirect design estimation of fractional order systems is proposed. In indirect fractional order approach, fractional order plant is shifted in the frequency domain and the equivalent plant is modeled by employing binomial approximation. The equivalent fractional order plant obtained is used for the design of the controller. While designing fractional order controllers, robustness and handling sensitivity to parametric variations are of key importance. Therefore, indirect fractional order approach is used, which gives the flexibility to adjust the maximum sensitivity according to the system requirements and eliminates the need for external IMC filter. IMC filter added externally results in an additional phase lag of the system. The proposed design method excludes external IMC filter and the binomial expansion used helps in achieving the internal filter which results in better transient response. This is termed as Indirect Fractional order IMC based fractional order PID controller.
Indirect optimal tuning rules for fractional order proportional integral derivative controller Rishika Trivedi, Bharat Verma, Prabin K. Padhy International Journal of Numerical Modelling Electronic Networks Devices and Fields, 2021 In this article, the tuning rules of fractional order PID controller are derived using Indirect Design Approach‐1. In Indirect Design Approach‐1, the plant is shifted in the frequency domain using the shifting parameter ψ. The tuning rules of stochastically optimized fractional order PID controllers exist in literature for the fixed values of maximum sensitivity. Maximum Sensitivity or robustness of the process is application dependent. Due to complex fractional order mathematics, the design of fractional order PID controller is complex. Therefore, in this article, new optimal tuning rules for FOPID controller are proposed using the shifted version of the plant. The adjustable robustness is achieved by varying tuning variable ψ which has a linear relation with the Maximum Sensitivity, Gain margin and Phase Margin. The range of ψ within which it can be varied is also proposed for both stable and unstable processes. Simulation is carried out in the MALTAB environment for validating the proposed methodology. A stable and an unstable first order process with time delay is considered for simulation. For the practical viability and novelty, a real‐time experiment on the level control of Canonical Tank using the proposed methodology is shown.
Design of fractional IMC controller for stable fractional order systems using firefly algorithm Kurnam Gnaneshwar, Rishika Trivedi, Bharat Verma, Prabin Kumar Padhy Proceedings 2021 International Conference on Control Automation Power and Signal Processing Caps 2021, 2021 In this paper design of fractional order controller for stable systems based on the IMC approach is presented. The proposed method creates a filter internally; therefore, phase lag obtained by an external filter in the system response can be avoided with the proposed method. It has the capacity to regulate the transient response and robustness of the system with a single parameter. This parameter plays a vital role to obtain the optimum response. Hence, a metaheuristic algorithm is considered. Numerous performance parameters and performance are considered to examine the proposed methodology efficacy. The proposed methodology performance has been carried out under load disturbance, robustness analysis. Also, its performance has been compared with various existing techniques.
Optimal Tuning of FOPID Parameters with SFL Algorithm for an AVR System Kurnam Gnaneshwar, Rishika Trivedi, Prabin Kumar Padhy Proceedings of the 4th International Conference on Electronics Communication and Aerospace Technology Iceca 2020, 2020 An approach to sustain the Automatic Voltage Regulator (AVR) system voltage at the desired level using the Fractional Order PID controller (FOPID) were described in this article. Numerous optimization techniques are used for the optimal tuning of FOPID parameters with the proposed objective function. The performance of this objective function has been compared with existing ones to validate its effectiveness. Moreover, load disturbance analysis is carried out on the FO-PID controller along with the robustness analysis under uncertainties of exciter parameters.
Design of FPI-PD controller for brushless DC motor Roshan Bharti, Rishika Trivedi, Prabin Kumar Padhy 2018 2nd IEEE International Conference on Power Electronics Intelligent Control and Energy Systems Icpeices 2018, 2018
