Mattijs Ghijsen

Market-Based Coordination of Domestic Appliances

March 17th, 2010

Another paper that will be presented at i-sup 2010 by one of my colleages at VITO is about applying market-based coordination to domestic applicances. Controlling devices in the household domain brings a number of challenges such as responsiveness to users and access to the control process of the appliance. In the paper we show how we deal with these issues. We also discuss an experiment in which a fridge, a washing machine, a dishwasher and a MicroCHP coordinate their activities to reduce peak load and optimize the reuse of electricity produced by the MicroCHP.

Tags: coordination · homelab · markets · PowerMatcher

Coordinated Charching of Electric Vehicles

March 12th, 2010

In the past months I’ve been working at VITO on coordinated charging of electric vehicles on a distribution grid. In particular we have been looking at a market based coordination mechanism (PowerMatcher). In this coordination mechanism, cars and households bid for electricity in a single-shot multi-unit auction.

In the first part of the study we explored at which level of electric vehicles, problems on the distribution grid start to occur. We show that at a certain level of plugin hybrid electric vehicles (PHEV) and fully electric vehicles (EV), peak load exceeds the tranformator rating and undervoltage and unbalance exceed the norm. In the second part of the study we show how a market based approach to coordination is able to mitigate these problems. Even in the worst case scenario with 50% PHEV and EV, peak load stays well below the tranformer rating and undervoltage is within the norms.

I will be presenting a paper on this topic in April at the i-sup 2010 conference.

Tags: auctions · coordination · electric vehicles · markets · PowerMatcher

Paper: Mobile Phone Experiment

January 22nd, 2010

My former collegue at the UvA, Henriette Cramer, wrote a paper on the mobile phone experiment: Trying Too Hard? Effects of Mobile Agents’ (Inappropriate) Social Expressiveness on Trust, Affect and Compliance. In April this year, she will present this paper at the CHI 2010 conference in Atlanta.

Tags: Android · user experiment · Wizard of Oz

Mobile Phone Experiment

June 30th, 2009

I have been implementing an application for a Wizard of Oz experiment with a mobile phone. The experiment has been designed and carried out by Henriette Cramer (in the context of the DIADEM project).

The system consists of two applications; the observer (Wizard of Oz) application running on a normal PC and the user application running on the HTC Dream phone. The observer application is a Java application which enables us to pretend the application on the mobile phone is quite intelligent while actually the observer is doing all the intelligent stuff. The user application was implemented using the Android development platform.

The main part of the application was an “indoor-GPS” system. The phone application shows a map of a part of an office building and displays the position of the user. Because actual GPS is not reliable indoors and not sufficiently accurate, camera’s were used to see the position of a participant. The wizard uses these video images to determine where the participant is and click on a map in the observer application to indicate the current position of the participant. The observer application will then send this position to the phone application using either a wireless or GPRS connection.

I talked to a few participants after they did the experiment and they didn’t realize it was a WOZ experiment. At least for them the application behaved convincingly enough to think that somehow GPS was working indoors.

Tags: Android · Google · HTC dream · user experiment · Wizard of Oz

Paper: Adaptive Hierarchical Multi-Agent Organizations

May 12th, 2009

We have written a paper which is our contribution to a book about the results of the ICIS project. In this paper we show how a hierarchical agent organization can adapt its organization according to the balance in workload among the agents. The result is that these adaptive hierarchies perform better while less information exchange between agents is needed.

This example is the result of a simulation in the RoboCupRescue simulation environment and it shows an evolving hierarchical organization over time. Initially, at t=0, the organization consists of 2 layers:

[Read more →]

Tags: adaptive · hierarchy · ICIS · MAS · organization · paper

Simulator used for teaching

April 20th, 2009

The simulation environment is now actually being used in teaching a Multi-Agent Systems course. This course is taught in the 3rd year of the Information Science bachelors program at the UvA. In a series of assignments the students will be programming a team of simple agents that are capable of searching the map and the rescue of victims. First, the students will have to build agents that act alone. Once they have these agents up and running, the students will have to enable their agents to work together to rescue the victims.

Tags: MAS · simulator · teaching

Coordination Demo

April 2nd, 2009

I have been working on implementing different types of agent organizations. In the videos below, a team of agents is working together to search and rescue a number of victims. In the first video, agents use mutual adjustment as a coordination mechanism. In the second video, agents use a centralized coordination mechanism.

Mutual Adjustment

This is a decentralized organization where agents use mutual adjustment to coordinate the search and rescue effort. When an agent finds a victim, it will send a request for help to the other agents (an agent cannot rescue a victim alone). When another agent receives such a request for cooperation, it can send an offer which includes a time window in which the agent will available to assist in the rescue of that victim. When enough agents have responded to a request, an agent will send a confirmation of the definite time at which the rescue should take place.

[Read more →]

Tags: communication · coordination · MAS · Search and Rescue

Simulator communication

March 12th, 2009

In the simulator, agents can communicate with each other using a (simulated) wireless network. In order to manipulate the robustness of the communication network, the number of communication cells can be varied. By increasing the number of cells, the number of routes by which a messages can travel through network also increases. In the case of a failure in one of the communication cells, a network with more communication cells will offer more alternative routes for a message to be delivered at its receiver.

The examples below show different communication networks that all cover 75% of the grid.

Tags: communcation · MAS · Search and Rescue · simulator

Simulator Obstacles

March 6th, 2009

One of the features of the simulator is to create obstacles on the grid. Agents cannot move between grid cells if there is an obstacle. To guarantee there still is a route between any two grid cells, a minimum spanning tree algorithm is used. Examples of search grids with different levels of obstacles are shown below:

Tags: MAS · obstacles · Search and Rescue · simulator

Simulator

February 5th, 2009

Last summer I have been working on a simulation environment for my research on Multi-Agent Organizations. We needed a simulator in which we could have a large degree of control over environment, task and organization parameters. The result is a search and rescue environment in which agents have to search an area for victims. When a victim is found, the victim needs to be rescued. Depending on the amount of effort and resources needed to rescue a victim, agents have to coordinate their actions.

The next step is to develop different types of organizations and start running some exiting experiments!

Tags: MAS · Search and Rescue · simulator