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Chattering Free Sliding Mode Control and State Dependent Kalman Filter Design for Underground Gasification Energy Conversion Process

Ahmad, Sohail; Uppal, Ali Arshad; Azam, Muhammad Rizwan; Iqbal, Jamshed


Sohail Ahmad

Ali Arshad Uppal

Muhammad Rizwan Azam


The fluctuations in the heating value of an underground coal gasification (UCG) process limit its application in electricity generation, where a desired composition of the combustible gases is required to operate gas turbines efficiently. This shortcoming can be addressed by designing a robust control scheme for the process. In the current research work, a model-based, chattering-free sliding mode control (CFSMC) algorithm is developed to maintain a desired heating value trajectory of the syngas mixture. Besides robustness, CFSMC yields reduced chattering due to continuous control law, and the tracking error also converges in finite time. To estimate the unmeasurable states required for the controller synthesis, a state-dependent Kalman filter (SDKF) based on the quasi-linear decomposition of the nonlinear model is employed. The simulation results demonstrate that despite the external disturbance and measurement noise, the control methodology yields good tracking performance. A comparative analysis is also made between CFSMC, a conventional SMC, and an already designed dynamic integral SMC (DISMC), which shows that CFSMC yields (Formula presented.) and (Formula presented.) improvement in the root mean squared tracking error with respect to SMC and DISMC, respectively. Moreover, CFSMC consumes (Formula presented.) and (Formula presented.) less control energy as compared to SMC and DISMC, respectively.


Ahmad, S., Uppal, A. A., Azam, M. R., & Iqbal, J. (2023). Chattering Free Sliding Mode Control and State Dependent Kalman Filter Design for Underground Gasification Energy Conversion Process. Electronics, 12(4), Article 876.

Journal Article Type Article
Acceptance Date Feb 7, 2023
Online Publication Date Feb 9, 2023
Publication Date Feb 2, 2023
Deposit Date Mar 10, 2023
Publicly Available Date Mar 13, 2023
Journal Electronics (Switzerland)
Electronic ISSN 2079-9292
Publisher MDPI
Peer Reviewed Peer Reviewed
Volume 12
Issue 4
Article Number 876
Keywords Underground coal gasification (UCG); State-dependent Kalman filter (SDKF); Chattering-free sliding mode control (CFSMC); Energy conversion systems
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Copyright Statement
© 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (

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