On the Benefits of Relaxing the Periodicity Assumption for Networked Control Systems over CAN

A vast majority of control systems require the use of networks for the communication between the different agents: sensors, controllers, and actuators. The existing paradigm regards the messages, between sensors and controllers and between controllers and actuators, as periodic. Although this strategy facilitates the analysis and implementation, it leads to a conservative usage of the communication bandwidth. Based on previous work by the authors, an aperiodic strategy is proposed in this paper for the dynamic allocation of bandwidth according to the current state of the plants and the available resources. The case of control loops closed over Controller Area Networks (CANs) is discussed in detail and illustrated on a train car.