Robustness analysis method for underwater vehicle control systems

Current stability and performance robustness techniques are surveyed and evaluated for application to the underwater vehicle control system design problem. These robustness techniques have been classified into the following five categories: matrix perturbation techniques, characteristic equation methods, structured singular value techniques, input-output methods, and Lyapunov methods for nonlinear systems. Matrix perturbation and characteristic equation techniques are conceptually and computationally simple approaches to determining the stability robustness of a linear system to parameter uncertainty or variations. If the control system is determined robust to parametric uncertainty, the stability robustness of the control system to unmodeled dynamics and parametric uncertainty can be tested with the more sophisticated structured singular value technique. The structured singular value approach can also be used to determine the performance robustness of the control system. The input-output and Lyapunov methods are the only methods applicable to nonlinear systems