Control Loop Scheduling Paradigm in Distributed Control Systems

The performance Distributed Control System (DCS) depends not only on the operation of the individual components, but also on their interaction and cooperation. Therefore, the rules that allow the exchange of messages, i.e. message scheduling policy, is a key issue in terms of system performance. For control applications where control loops are closed over communication networks, this is especially true. Traditional scheduling policies are based on models and techniques that do not take application demands into account. This precludes the dynamic adaptation of the use of the communication bandwidth according to the application needs. To overcome this problem and focusing on control applications, we present an early specification of a novel scheduling technique: Large Error First (LEF). This scheduling algorithm uses feedback information from the application in order to assign communication bandwidth to each individual component. We studied the performance of a distributed application when the messages are sent according to this novel scheduling policy and encouraging simulation results have been obtained.