A study on the Automatic Manoeuvring System of a ship based on ILQ Optimal Servo Theory

Abstract

In the application of the linear quadratic (LQ) optimal regulator theory to control system design, it is difficult to find suitable weighting matrices Q, R in the performance function. That is, the designer must resort to trial and error iteration to find them. And so it is rather difficult to design the optimal control system. The inverse linear quadratic (ILQ) optimal servo theory was recently proposed, this design theory was developed from the practical view point by applying some results on the inverse problem of LQ regulator. In this method there is a close relationship between the characteristic of the transient response of the control system and the design parameters. When the design condition is fulfilled, it is able to construct a control system which has no interaction between the controlled variables, and it is also able to express the optimal feedback gain in terms of the system matrices and the design parameters. In this paper, the authors attempted to apply ILQ optimal servo theory to the design of a control system for the manoeuvring motion of a ship. It is shown that by the ILQ design method the control system for the manoeuvring motion of a ship can be designed very easily compared with the usual LQ design method. Response characteristics can be selected with design parameters. A control system can be constructed no to interact between the control variables, and as the gain is expressed in terms of the system matrices and the design parameters, it is able to construct a control system which is adaptable to the change of the characteristic of the controlled object.