Hybrid modeling and simulation of plant/controller combinations

In order to design controllers, models of the system to be controlled (the plant), and models of the controller are developed, and the performance of the controlled system is evaluated by means of, for instance, simulation. The plant and controller can be modeled in the continuous-time domain, the discrete-event domain, or in a combination of these two domains, the so-called hybrid domain. It is very convenient to have all these combinations available in one single formalism. In this paper, the hybrid chi (Chi) formalism is introduced and used to model a simple manufacturing system consisting of a production machine that is controlled by a PI controller with anti-windup. The plant is modeled in the continuous-time domain as well as in the discrete-event domain. Likewise, the controller is modeled in both domains. Then, several (hybrid) plant/controller combinations are made. It is shown that the chi language facilitates modeling of these combinations, because the individual plant and controller specifications remain unchanged. The chi simulator is used to obtain the respective simulation results.