Robust deadlock control for automated manufacturing systems with a single type of unreliable resources

Abstract

In automated manufacturing systems, resource failures are often inevitable. They reduce the number of available resources and may cause some processing routes of parts to halt and sometimes the whole system to shutdown. This article focuses on the robust deadlock control problem in automated manufacturing systems with multiple resource failures. To obtain such a robust controller, we first put forward a new concept of blocked states of automated manufacturing systems. From such a state, the production of some part types through one of their routes is blocked as caused by resource failures, and only after some failed resources are repaired, these parts can resume their normal processing. Then, these blocked states are characterized in terms of emptied siphons caused by resource failures. In order to prevent the system from deadlocks and blocked states, a robust controller is proposed by the following two steps. First, for siphons without unreliable resources, optimal deadlock control places are added. Then for siphons which contain unreliable resources, new control places are devised to ensure that they could be marked even when resource failures happen. It is proved that the proposed controller can guarantee that all types of parts can be processed repeatedly as long as one unit of unreliable resources can still work. This means that the proposed controller is of greatest robustness, that is, it can tolerate a maximum number of resource failures. Some examples are provided to illustrate the proposed method and show the advantage over the previous ones.

Elementary Siphon-Based Robust Control for Automated Manufacturing Systems With Multiple Unreliable Resources

“…It is obvious that R(p 9 , S 1 ) = 1, R(p 9 , S 2 ) = 0, R(p 10 , S 1 ) = 1, and R(p 10 , S 2 ) = 1. We have the adjoint sets of the two elementary siphons: [18], [19], [32] and this paper for Fig. 3 Fig.…”

“…3 is 74). The performance of the obtained controller in this paper is compared with those in [18], [19], and [32] by Table 3 that shows the number of reachable markings according to the failure times of the unreliable resource p 9 .…”

“…The policies in [31] suffer from high computational complexity since both of them need to enumerate all reachable markings. In [32], a robust deadlock control policy with strong robustness is developed, where blocked states of AMSs are introduced. It allows failures of maximal units of an unreliable resource and has a compact structure while it cannot process systems with multiple unreliable resources.…”

Robust Deadlock Control for Automated Manufacturing Systems Based on the Max-Controllability of Siphons

“…This example provides a large U-GS 3 PR with a type of unreliable resources. However, the robust deadlock control policies in [31], [33], [36], [38], [39], [41] are all proposed for U-S 3 PRs. It means that the systems studied in this paper are more general than the ones in these works.…”

A New Method for Solving Deadlock Using Genetic Algorithms

“…In [13] the researchers focus on the automated manufacturing system deadlock control with the failure of multiple resources. The methodology presents two steps.…”