A Robust H∞ Speed Tracking Controller for Underwater Vehicles via Particle Swarm Optimization

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Author(s) 
MohammadPourmahmood Aghababa, Mohammd Esmaeel Akbari 

KEYWORDS 
H∞ controller, underwater vehicles, particle swarm optimization, robustness.


ABSTRACT 
This paper presents an H∞ controller designing method for robust speed tracking of underwater vehicles, using Particle Swarm Optimization (PSO). Nonlinearity mapping of the underwater vehicles model to a nominal linear model, by employing a linear controller for a nonlinear model, is one of the main contributions of this paper. For reaching the linear H∞ controller, the nonlinear models linearized around an operating point. Both nonlinear and linearized models are discussed. A brief explanation of H∞ synthesis is given. Also frequency dependent weighting functions are used for penalizing tracking errors, setpoint commands and measured outputs noises using PSO. Obtained controller is reduced order to achieve a lower order controller. After simulating the reduced order H∞ controller it is embedded into the nonlinear model. By nonlinear simulations, robustness and efficient performance of the H∞ controller is shown. Control efforts of actuators revealed no saturation, therefore it is feasible to implement.


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