A novel hierarchical control architecture for a class of discrete-event systems

Abstract

This paper proposes a novel hierarchical control architecture for a class of discrete-event systems. Under the proposed control scheme. a max-plus algebra model is introduced on the upper level to provide an optimal online plan. On the lower (implementation) level, min-plus algebra is used to solve cooperation prob lems between sub-plants as well as problems caused by unexpected events. A simple rail traffic example is gIven to show the effectiveness of the idea.

Informatics in Control, Automation and Robotics II

“…Detailed information about how to find all feasible A 02 (i.e. all feasible plans) can be found in (Li et al, 2004). In particular, it was shown there that ∃k ≤ n, A k 0 (i, i) > ⇔ A 02 is infeasible.…”

“…For the simple rail traffic network in Figure 3, which was shown in (Li et al, 2004), "first order control arcs" ensure the safe resource sharing between cycles and "first order travelling arcs" ensure that each train starts its new journey (cycle k + 1, k ≥ 1) a specified number of time units after its arrival at its destination in cycle k. As a review of the example, the network involves 3 trains and 3 tracks. Initially, train 1, 2 and 3 are located at the end points of the 3 tracks, i.e.…”

“…In the middle of both track AO and track CO, double-line track segments are available, which make it possible that two trains pass each other between points N 1 and M 1 or N 2 and M 2 , respectively. In (Li et al, 2004), all trains stopped after they arrived at their destinations (i.e. after one cycle).…”

“…The offline process is used to find all feasible plans based on the system topology and an offline optimal plan list, which can be interpreted as a timetable. The online part updates the feasible plan set (see (Li et al, 2004)), the optimal plan list and provides the time specification X(k) to the lower level.…”

“…There are 3 feasible plans in this case study (see previous work in (Li et al, 2004)). In a first step, a fixed optimal-time plan list is derived from offline simulations.…”