Physical Modeling of Controlled

For control law design it is necessary to work with controller models and plant models of diierent complexity. During the control law design iteration it should be possible to adjust both the complexity of the controller model and the complexity of the plant model in order to evaluate the compromise between necessary control complexity and achievable control performance. Controller models on the one hand are most commonly described as systems of basic block components ; plant models on the other hand are often described in form of physical system models. A block oriented control modeling environment like Simulink allows to build up control systems conveniently. But it does not support the user in the physical modeling in the same way. It could help the control engineer to work in a mode-ling environment, which allows both physical system modeling and block diagram modeling. In this paper, by example of a controlled aircraft, the realisation of such a combination in the object-oriented modeling environment Dymola is described. It would be helpful for a control engineer to be able to work with physical models in the same way he is used to work with controller models. That allows to increase the complexity of the physical model gradually within the controller design process. The most natural way of modeling physical systems is the modeling of physical objects and phenomena, which are connected according to their physical interaction. This is diierent from modeling all phenomena as functions and signal ows as it is convenient for controller modeling. An aircraft consists of a variety of diierent components and systems. These represent the interacting disciplines which are involved in aerospace engineering (e.g. ight mechanics, aerodynamics, engine). In the following section, the realisation of such an approach in Dymola 4, 3] is described. 1.1. Aircraft object model One way to describe an aircraft is as follows: An aircraft consists of a body (fuselage and wing), which is powered by one or more engines. Gravity is acting at an aircraft in the way as it is acting at any object with mass. The aerodynamics describes the eeects of the air, which is innuenced by the surrounding atmosphere and additional winds. Each of these phenomena is most conveniently described as one physical object. All objects which form the aircraft are connected according to Fig. 1. Fig. 1: Object diagram of aircraft In order to make the understanding of each object …