Submarine depth and pitch control

An introduction to the design procedures which should be employed for a multivariable system with difficult control requirements is presented. To design an LQG or H_∞ controller the system model must be selected in addition to the cost function weights. There is often more freedom in the selection of the system model and in its representation than might be first thought. The submarine depth control problem is a useful vehicle to explore the design issues since it is two input and two output and the order of the system is not so large that it will hide the essential characteristics. Moreover, there are limitations of the use of the actuators which complicates the design process, making the choice of weightings more challenging