Fredrik Wernstedt

Agent-Based Approaches to Transport Logistics

This paper provides a survey of existing research on agent-based approaches to transportation and traffic management. A framework for describing and assessing this work will be presented and systematically applied. We are mainly adopting a logistical perspective, thus focusing on freight transportation. However, when relevant, work of traffic and transport of people will be considered. A general conclusion from our study is that agent-based approaches seem very suitable for this domain, but that this still needs to be verified by more deployed system.

Demand side management in district heating systems

This paper describes a multiagent system that has made the voyage from research project to commercialised product. The purpose for the multiagent system is to dynamically control a system so that the load of the system is below certain threshold values without reduction of quality of service and by that, to avoid the usage of top load production sources and to reduce energy consumption. The fundamental idea behind the system is that a large number of small local decisions taken all in all have great impact on the overall system performance. A field-test as well as a return of investment analysis are presented.

A multi-agent system architecture for coordination of just-in-time production and distribution

A multi-agent system architecture for coordination of just-in-time production and distribution is presented. The problem to solve is twofold: first the right amount of resources at the right time should be produced, then these resources should be distributed to the right consumers. In order to solve the first problem, which is hard when the production and/or distribution time is relatively long, each consumer is equipped with an agent that makes predictions of future needs that it sends to a production agent. The second part of the problem is approached by forming clusters of consumers within which it is possible to redistribute resources fast and at a low cost in order to cope with discrepancies between predicted and actual consumption. Redistribution agents are introduced (one for each cluster) to manage the redistribution of resources. The suggested architecture is evaluated in a case study concerning management of district heating systems. Results from a simulation study show that the suggested approach makes it possible to control the trade-off between quality of service and degree of surplus production. We also compare the suggested approach to a reference control scheme (approximately corresponding to the current approach to district heating management), and conclude that it is possible to reduce the amount of resources produced while maintaining the quality of service. Finally, we describe a simulation experiment where the relation between the size of the clusters and the quality of service was studied.

A Framework for Evaluation of Multi-Agent System Approaches to Logistics Network Management

We study the applicability of multi-agent systems (MAS) to production and logistics network management. The goal is to create and evaluate sets of intelligent agents that can cooperatively support production and logistics network decisions, as well as to compare their performance to other more traditional methods. A short description of supply chains is given, as well as a formal characterization of the problem space under investigation. We outline a general simulator that allows for a systematic evaluation of different multiagent approaches across the different parts of this problem space. This is illustrated by a case study on district heating systems. A major concern in this domain is how to cope with the uncertainty caused by the discrepancies between the estimated and the actual customer demand. Another concern is the temporal constraints imposed by the relatively long production and/or distribution times. In the case study we show how to lessen the impact of these problems by the usage of agent clusters and redistribution of resources.

Embedded Agents for District Heating Management

We investigate the applicability of multi-agent systems as a control approach for district heating systems. The consumers, i.e., the heat exchange systems, in current district heating systems are purely reactive devices without communication capabilities. In this work, the possibilities of a new type of heat exchanger system that has an open software environment and communication capabilities are explored. Operators of district heating systems have several, often conflicting, goals, e.g., to satisfy the demand of the customers and to minimize production costs. Our approach is to embed a cooperative agent in each consumer. Results from a simulation study indicate that the approach makes it possible to reduce production while maintaining the quality of service. In another experiment in a controlled physical environment, two agent-based approaches are evaluated and compared to existing technologies. The experiment shows that it is possible to automatically load balance a small district heating network using agent technology.

A Case Study on Availability of Sensor Data in Agent Cooperation

Multi-agent cooperation can in several cases be used in order to mitigate problems relating to task sharing within physical processes. In this paper we apply agent based solutions to a class of problems defined by their property of being predictable from a macroscopic perspective while being highly stochastic when viewed at a microscopic level. These characteristic properties can be found in several industrial processes and applications, e.g. within the energy market where the production and distribution of electricity follow this pattern. We evaluate and compare the performance of the agent system in three different scenarios, and for each such scenario it is shown to what degree the optimization system is dependent on the level of availability of sensor data.