Students from the programs Engineering Physics, Electrical Engineering and Mechanical Engineering have, in their bachelor's project, designed and constructed a battery-powered rail-bound vehicle with the purpose of being as energy efficient as possible. The project also aims to participate in the Delsbo Electric competition, where students from all over Sweden meet to compare their vehicles.
The students have been working with the rail-bound vehicle for several months and the projects is concluded with a physical driving test on a track at Jernhusen in Fjällbo, which is on the outskirts of Gothenburg. The vehicle, which has been designed and constructed based on an own concept, is quickly assembled by the students, and after a bit of tinkering with the electric motor, the team sets off on a first test run.
Once the first ride is over to make sure the brakes and everything else is working, it's time to put on the streamlined fairing, which is there to reduce drag. It is a wire frame construction that the students have optimized based on computer simulations. It has then been covered and heated with a vinyl film purchased from a regular store.
"We notice a difference when we put the fairing on, but at these low speeds, the air resistance is not what gives the greatest effect. The electric motor and the mechanical parts play a much bigger role in low speeds. But in an even competition, that can be the decisive factor, so it's important to streamline as much as possible. But we managed to halve the drag with the help of the simulations, and at high speeds it becomes very important, says Tim Pagrell, who studies Engineering Physics and responsible for the simulations."
The vehicle is powered by a battery motor that is controlled using the Raspberry Pi operating system and programmed with Python. Many of the mechanical parts such as the bearing housings and axles have been manufactured by students themselves in Chalmers makerspace Fuse lab. Other parts such as the wheels have been able to be reused from previous student projects.
"It’s been very good to be able to do so much practical work at Chalmers when it comes to manufacturing different parts. For example, after our first test, we noticed that the cart tilted a bit, which created quite large energy losses. So, before the final test today, we adjusted this with spacers, which worked very well, says Eskil Wirdheim, who studies the Mechanical Engineering program."
Delsbo Electric - a competition between students
One goal of the project has been to participate in Delsbo Electric. A competition where students test and compare which rail vehicle is the most energy efficient. The competition involves the vehicles being driven over three kilometers at an average speed of 10-15 kilometers per hour. It must also be able to transport a few people with a total weight of 300 kg. After the finish, the electricity consumption is checked and compared between the participants.
The competition is usually held in May but is currently postponed until after the summer. The vehicle and students all around Chalmers students have participated in the competition twice before, but then with only students from the Electrical Engineering program. This time it is a more mixed group that has been able to complement each other's knowledge.
"We have worked together on an overall level and learned from each other. Not everything is just about technology in a project like this. But then, of course, we have had the advantage of having different basic skills and knowledge. Naturally those of us who study electrical engineering have had the greatest responsibility for the electric motor and the machines for the mechanical part. Since then, Tim has been best suited to make simulations of air resistance since he is in Engineering Physics, says Anna Johansson, student at the Electrical Engineering program."
Interdisciplinary collaboration will be more common
Erik Hulthén is one of the initiators and supervisors of this year's project. Erik, who is also education area leader, predicts that this type of joint projects with students from different programs will become increasingly common.
"This is an example of a project that shows the importance of working interdisciplinary and with a systems perspective. Our signals from industry say they want to see more collaboration. The depth in each area is still and the students have shown that they can handle that. We also believe that the project can attract more students to Chalmers as it deals with electrical and mechanical engineering in combination, something that is up to date and that the industry is in demand. For next year, there are lots of ideas for further development, says Erik Hulthén."
More information
Design and construction of an energy-efficient rail-bound vehicle - For participation in the competition Delsbo Electric has been written by students: Erik Benjaminsson, David Einarsson, Anna Johansson, Lucas Kristiansson, Tim Pagrell and Eskil Wirdheim.
A bachelor's thesis in applied mechanics, product development and electric power.