Simon Collart-Dutilleul

ROBUST DYNAMIC CONTROL OF MULTI-PRODUCT JOB-SHOPS

Abstract This paper deals with the robustness of Dynamic Discrete Event Systems including time interval constraints. It recalls to mind a method to compute the passive robustness by the decomposition of the P-time Petri Net model into four sets. The computing algorithm of a lower bound for the maximal time disturbances allowed on a given point is presented. The main contribution concerns the active robustness. An algorithm providing a global robustness new lower bound is introduced.

Active robustness of a milk manufacturing workshop with time constraints

This paper deals with the active robustness of a milk manufacturing workshop including time interval constraints. Such systems have robustness properties towards time disturbances. The robustness property can be a static property, but using a dynamic control strategy may increase the robustness value. Controlled P-time Petri nets are used as a modelling tool. Some definitions and a series of lemmas are cited in order to build a theory dealing with robustness problems. In order to avoid the death of marks at the synchronisation transitions of the P-time Petri net model, a robust control strategy facing time disturbances is presented. The proposed approach tries to reject the disturbance as soon as it is observed. Furthermore, this approach is used by an algorithm computing an active robustness margin at a given node. It is illustrated step by step on an example of a milk manufacturing workshop. A comparison with the bound provided for the passive robustness is made.

Functioning mode Management and formal assessment of safety

Abstract This paper presents a methodology to assist the safety assessment of timed discrete event systems. The methodology is illustrated on a level crossing case-study. It is a critical component for the safety of railway systems. The first step consists in decomposing the system functioning into different functioning modes. Then under specific assumptions, a model is provided for each functioning. Then, our goal is to take out the forbidden state highlighted by a p -time Petri net modelling. This model deals with the requirements of the considered system and has to contain all the constraints that have to be respected. Considering a proposed technological solution, its global functioning is also decomposed in several modes. As a latter, the model of the solution can be assessed, mode by mode. This assessment is achieved comparing the state classes deduced from the requirement model and the state classes of the proposed solution.

Simulation and Optimisation of Lift Networks in a Provincial Skiing Resort

Abstract This research focuses on the planning of an Alpine skiing lift network in the Mount Carleton Provincial Park, located north of New Brunswick in Atlantic Canada. Linear programming LP and discrete event simulation are used to model ski lifts network and evaluate several ski lifts selection alternatives based on technological specification, network layout, valley development plan, and service quality standards. A good solution is found by using LP optimisation for chair lifts selection and discrete event simulation to evaluate skier lift waiting times and slopes usage rate, as a measure of service quality and compliance level with environmental constraints in the Provincial Park.