In: Control Engineering Practice, Vol. 6, No. 7, pages 889-895. 1998.
Abstract: This paper presents an implementation method for high-speed Petri-net-based controllers for time-critical control with parallelism, based on look-up tables. Unlike microprocessor-based software implementations, the method is based on hardware, and offers enough speed to control fast plants at low cost. The method is easily able to accommodate more complex control problems than hardwired implementations. The data structure and execution module are composed of common memory devices and simple logic gates. A modified matrix-based data structure, named the bi-column matrix-based data structure, is suggested. It has a regular form but retains the efficiency of list-based data structures. A sub-class of Petri nets is defined in order to fit Petri nets to the bi-column matrix-based data structure, and conversion to Petri nets of the sub-class is described. The matrix framework enables pipelined execution, which increases the performance in an efficient way. An event-driven evolution scheme is proposed as well, to enhance response time. This method is demonstrated by an implementation using a Xilinx 4000 series LCA. An example illustrates that the Petri-net-based controller is useful in a high-speed supervisor-control problem.
Keywords: Petri nets, parallel processing, real-time systems.