Robust Control of Diesel Ship Propulsion

The control of marine engines and propulsion plants is a field of increasing interest to the maritime industry. The author's participation in a number of closely related research projects together with practical shipboard experience allows Robust Control of Diesel Ship Propulsion to present a broad view of the needs and problems of the shipping industry in this area.

The book covers a number of models and control types: An integrated nonlinear state-space model of the marine propulsion system is developed. This is based upon physical principles that incorporate uncertainties due to engine thermodynamics and disturbances due to propeller hydrodynamics. The model employs artificial neural nets for depicting the nonlinearities of the thermochemical processes of engine power/torque generation and the engine-turbocharger dynamical interaction; neural nets combine the required mathematical flexibility and formalism with numerical training and calibration options using either thermodynamic engine models or measured data series. The neural state-space model is decomposed appropriately to provide a linearised perturbation model suitable for controller synthesis.

The proportional integral (derivative) control law is examined under the perspective of shaft speed regulation for enhanced disturbance rejection of the propeller load. The typical marine shafting system dynamics and configuration allow for a smart implementation of the D-term based on shaft torque feedback.

Full-state feedback control is, examined for increased robustness of the compensated plant against parametric uncertainty and neglected dynamics. The H-infinity requirements on the closed-loop transfer matrix are appropriately decomposed to similar ones on scalar transfer functions, which give specifications which are easier to manipulate.

In effect, the methods are comparatively assessed and suggestions for extensions and practical applications are given. This synthetic approach to the propulsion plant control and operational problems should prove useful for both theoreticians and practitioners, and can be easily adopted for the control of other processes or systems outside the marine field, as well.