Page 159 - IJOCTA-15-2

An International Journal of Optimization and Control: Theories & Applications
ISSN: 2146-0957 eISSN: 2146-5703
Vol.15, No.2, pp.354-367 (2025)
https://doi.org/10.36922/ijocta.1712

RESEARCH ARTICLE

A modified graphical based tuning and performance analysis of
second order LADRC using frequency domain technique for SISO
systems

1
1*
2
Janeshwaran Gunasekaran , Ezhilarasi Deenadayalan , Radhakrishnan Thota Karunakaran , and
Deepak Prasanna Rajendran 1
1 Department of Instrumentation and Control Engineering, National Institute of Technology,
Tiruchirappalli, India
2 Department of Chemical Engineering, National Institute of Technology, Tiruchirappalli, India
janeshg96@gmail.com, ezhil@nitt.edu, radha@nitt.edu, deepakprasannars@gmail.com

ARTICLE INFO ABSTRACT

Article History: This paper proposes a simplified frequency based tuning method for Second-
Received: October 18, 2024 order Linear Active Disturbance Rejection Control (SLADRC). By employing
Accepted: January 21, 2025 a 2-DOF structure for the controller, the challenge of optimizing numerous
Published Online: April 24, 2025 tuning parameters for complex systems is addressed. By considering the phase
margin (PM) as one of the design specifications, an admissible region is mapped
Keywords:
onto the Nyquist plot to identify the permissible bound for gain crossover fre-
Active disturbance rejection
quencies (ω gc), from the known system frequency points. Distinct controllers
Second order LADRC
Nyquist diagram with unique performance characteristics can be designed within the compre-
Optimal parameter tuning hensive set of design specifications (PM and ω gc). Subsequently, the optimal
tuning parameter values are determined by identifying the design specifica-
AMS Classification 2010: tions that yield the desired response and the minimum ITSE. Two distinct
93C05, 93C80 approaches are proposed for selecting suitable design specifications: an itera-
tive method and a heuristic-based method. These approaches rely on graphical
analysis of time-domain performance metrics and robustness analysis using the
disk margin. While the heuristic approach offers faster computation, the it-
erative method generally provides more accurate results. The reliability and
versatility of the proposed tuning technique are validated on five distinct bench-
mark systems. The systems with time delay and unstable dynamics explains
the detailed tuning procedure in performance study. In comparative study,
time delay with integrating system, pure integrating system and nonminimum
phase with higher order systems are considered, provides equivalent perfor-
mance with reduced computational effort. Additionally, it is experimentally
verified through a real-time speed control of a rotary servo system, achieving
an ITSE of 16.2 and a disk margin of 1.332, confirming its practical applica-
bility.

1. Introduction dynamics, model mismatches, and faster distur-
bance rejection capability. A combination of a
feedback controller and an extended state ob-
Rapid advances in engineering have brought new
server (ESO) forms the ADRC, achieving the de-
challenges to controller design. Recently, ADRC,
1
proposed by, has gained much importance due to sired performance in the presence of disturbances
and uncertainties by estimating the state vari-
its model-free approach, superior performance in
ables. However, the controller’s complexity arises
handling parameter uncertainties, unknown plant
*Corresponding Author
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