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Genetic algorithms based automatic boundary selection of robust H ∞ loop shaping pid control for DC/DC converter
(2013-07-12)
Olranthichachat, Piyapong
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Kaitwanidvilai, Somyot
H<inf>∞</inf> loop shaping is complicated controller and has high order. It is difficult to implement in practice. To overcome this problem, we propose an algorithm, Genetic Algorithms based Automatic Boundary Selection (GA-ABS) of Robust H<inf>∞</inf> loop shaping control, to design a robust controller. GA-ABS is used to solve the fixed-structure H<inf>∞</inf> loop shaping. Additionally, in the proposed technique, the Boundary Selection of Genetic Algorithms, which is normally difficult to select, is determined by using GA-ABS. The performance and robustness of the proposed controller are investigated in a buck converter in comparison with those of the controllers designed by conventional H<inf>∞</inf> loop shaping and ISE (Integral Square Error) methods. Results of simulations demonstrate the advantages of a simple structure and robustness against plant perturbations and disturbances of the proposed controllers. Experiments are also performed to verify the effectiveness of the proposed technique.
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Structured robust control for MIMO systems using artificial intelligent techniques
(2012-01-16)
Kaitwanidvilai, Somyot
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Olranthichachat, Piyapong
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Nimpitiwan, Natthaphob
In this chapter, a new technique called fixed-structure robust control using artificial intelligent (AI) technique is proposed to enhance both performance and stability of controlled system. In this approach, the structure of controller is specified and the robust stabilization problem is solved by AI techniques. The advantages of simple structure, robustness and high performance can be achieved. In this paper, two multiple inputs multiple outputs (MIMO) controller design problems, i.e., robust control design for electro-hydraulic servo system and fixed-structure robust mixed-sensitivity approach for three phase inverter are illustrated. Simulation results show that the proposed controller has simpler structure than that of conventional robust controller, and the stability margin obtained indicates the robustness of the proposed controller. © 2012 Springer Science+Business Media, LLC.
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Design of optimal robust PI controller for electro-hydraulic servo system
(2011-08-24)
Olranthichachat, Piyapong
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Kaitwanidvilai, Somyot
This paper proposes a new technique to design an optimal robust PI-controller for electro-hydraulic servo system to achieve both the robustness and performance. Comparative study between the conventional robust control and the proposed technique is included in the paper. Particle Swarm Optimization (PSO) is adopted to simplify the solving of structured robust control problem to realize the practical robust controller. Simulation results show that the proposed controller has simpler structure than that of the conventional robust loop shaping controller, and the stability margin obtained indicates the robustness of the proposed controller. Simulation and experimental results verify the effectiveness of the proposed algorithm.
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Enhancing the performance of fixed-structure robust loop shaping control using genetic algorithm approach
(2011-07-26)
Olranthichachat, Piyapong
;
Kaitwanidvilai, Somyot
This paper is proposed an algorithm, Genetic Algorithm (GA) based fixed-structure H<inf>∞</inf> loop shaping control, to the problem-solving of conventional H<inf>∞</inf> loop shaping, such as high-order and difficult to be usable in general. In this approach, a structure of controller is specified combine H<inf>∞</inf> loop shaping method is solved by GA algorithm. Additionally, in the proposed technique, the desired performance weighting function, which is defined by using GA. The performance and robustness of the proposed controller are investigated in a pneumatic servo system in comparison with that of the controller designed by conventional H <inf>∞</inf> loop shaping. Results of simulation demonstrate the advantages of simple structure and robustness against plant perturbations and disturbances of the proposed controller. Experiments are performed to verify the effectiveness of the proposed technique.
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Structure specified robust H∞ loop shaping control of a MIMO electro-hydraulic servo system using particle swarm optimization
(2011-07-26)
Olranthichachat, Piyapong
;
Kaitwanidvilai, Somyot
A fixed-structure controller based on robust H∞ loop shaping control is proposed in this paper. It can be used to guarantee the robust performance under a structure-specified controller. In this proposed technique, Particle Swarm Optimization (PSO) is applied in the design controller, and the inverse of infinity norm from disturbances to states is formulated as the objective function in searching the optimal controller. Simulation results of MIMO electro-hydraulic servo system show that the proposed controller has simpler structure than that of the conventional H<inf>∞</inf> loop shaping controller and its stability margin is near the H<inf>∞</inf> loop shaping controllers.
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Robust loop shaping-fuzzy gain scheduling control of a servo-pneumatic system using particle swarm optimization approach
(2011-01-01)
Kaitwanidvilai, Somyot
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Olranthichachat, Piyapong
In this paper, a new technique called robust loop shaping-fuzzy gain scheduled control (RLS-FGS) is proposed to design an effective nonlinear controller for a long stroke pneumatic servo system. In our technique, a nonlinear dynamic model of a long stroke pneumatic servo plant is identified by the fuzzy identification method and is used as the plant for our design. The structure of local controllers is selected as PID control which is proven by many research works that this type of control has many advantages such as simple structure, well understanding, and high performance. The proposed technique uses particle swarm optimization (PSO) to find the optimal local controllers which maximize the average stability margin. In addition, performance weighting function which is normally difficult to obtain is automatically determined by PSO. By the proposed technique, the RLS-FGS controller can be designed, and the structure of local controllers is still not complicated. As seen in the simulation and experimental results, our proposed technique is better than the classical gain scheduled PID controller tuned by pole placement and the conventional fuzzy PID controller tuned by ISE method in terms of robust performance. © 2010 Elsevier Ltd. All rights reserved.
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Robust loop shaping control for designing high performance ACMC DC-DC converter
(2010-12-01)
Kaitwanidvilai, Somyot
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Olranthichachat, Piyapong
DC-DC converter is an important circuit in Micro-grid system. To design a high performance and robust controller for this circuit, H infinity loop shaping gains increasing attention in the controller design. Being complex and high-order, robust controllers designed by H<inf>∞</inf> loop shaping are difficult to implement in practice. To overcome this problem, an algorithm, Particle Swarm Optimization (PSO) based fixed-structure H<inf>∞</inf> loop shaping control, has been proposed to design a robust controller. PSO algorithm is used to solve the H<inf>∞</inf> loop shaping design problem under a structure-specified controller. Additionally, in the proposed technique, the performance weighting function, which is normally difficult to obtain, is determined by the PSO. Simulations are performed to verify the effectiveness of the proposed technique.
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Fixed-structure mixed sensitivity/model reference control using evolutionary algorithms
(2009-01-01)
Srithongchai, Pitsanu
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Olranthichachat, Piyapong
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Kaitwanidvilai, Somyot
This paper proposes a mixed sensitivity/model reference control using evolutionary algorithms. The proposed technique can solve the problem of complicated and high order controller of conventional H∞optimal control. In addition, time domain specifications such as overshoot, undershoot, rise time can be incorporated in the design by formulating the appropriate fitness function of compact genetic algorithms. By the proposed approach, robustness and performance in terms of frequency domain and time domain specifications can be achieved simultaneously. Simulation results in a servo system verify the effectiveness of the proposed technique.

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