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Building a test rover for RIMFAX, the Norwegian georadar on Mars

By Berit Ellingsen

This summer, two Master’s students from the University of Oslo assembled a rover that will be used for testing RIMFAX on Earth

Marius Anfindsen (left) and Fredrik Leiros Nilsen (right) with the rover in front

- The rover is commercially available as a pre-built solution and can be remote controlled. But in order to simulate a rover driving on Mars, the test rover needed to be modified to drive autonomously, says Marius Anfindsen, Master’s degree student at the University of Oslo.

Turning the remote controlled commercially available rover into an autonomously driving test platform for RIMFAX became the task of the two Master’s degree students working at CENSSS this summer.

The students also participated in the day-to-day operations of RIMFAX and NASA’s rover Perseverance on Mars. This meant sitting in at the meetings with NASA’s Jet Propulsion Laboratories at Caltech in the US, together with the rest of the research teams that are working with Perseverance.

As part of the daily operations of RIMFAX on Mars, the Master’s students also performed the uplink and downlink checks before and after each work day on the red planet.

Read more about this student work here.

Required practical work

The new test rover at CENSSS needed, among other things, software for autonomous driving and a web interface for easy access and control of the rover.

- In order to drive autonomously, the rover must know its own position accurately. That is provided by a GPS receiver and a GPS base station for correcting the data received from the GPS satellites so that that the positioning is accurate down to just a few centimeters, says Fredrik Leiros Nilsen, the second of the two Master’s students working at CENSSS this summer.

Thus, the test rover also needed a GPS receiver and an antenna for the GPS signals, and a gyroscope and accelerometer to sense its own movements. These were assembled on the rover by the Master’s degree students.

- We also coded the software for autonomous driving with GPS, created the web interface for that and mounted the antenna and a copy of the georadar RIMFAX on the rover. Finally, we tested everything by driving the rover on the parking lot outside the CENSSS building, and downstairs in the basement when the weather was bad, says Anfindsen.

Assembling all of this and mounting it on the rover took some work with both screw drivers, soldering iron and laser cutter, and even 3D-printing some parts.

Theoretical knowledge needed

Both Anfindsen and Nilsen are Master’s degree students in Mathematical Design and Automatic Systems at the Department of Technology Systems at the University of Oslo.

- When working with the GPS receiver and coding for the autonomous driving, the most challenging task turned out to be compiling the data from the GPS receiver, the accelerometer and the gyroscope into one useable result, Nilsen says.

Here, the knowledge the students had from their course in mathematical modelling of dynamic systems, as well as coding for machine learning, turned out to be very useful.

Both students enjoyed the combination of practical and theoretical work, and hands-on problem solving that modifying the test rover required.

- Keeping the overview and correct structure in a large amount of code such as here, and working from start to finish on a relatively large project like this, were the most educational parts of the job for me, Anfindsen says.

Nilsen agrees that one of the most challenging tasks was to ensure that all the individual components worked well together on the test rover.

- This required a lot of trial and error, and some head scratching in between. But we received good help from CENSSS and the University of Oslo, and had a lot of freedom to solve the challenges in our own way, Nilsen says.

Tangible results of the work

One of the most satisfying parts of the job was when the two Master’s degree students could finally test drive the rover and see the tangible results of their hard work.

- It was really great to watch the rover handle its first U-turn, while driving autonomously as we had coded it to do, and seeing that it moved as it should, Anfindsen says.

Both students agree that although this took a lot of work, they did not need to work long into the night.

- We didn’t work into the evenings, and I don’t think that would have helped solve our challenges either. It was better to finish at the usual work time, and come back rested and refreshed the next day, Nilsen says.

- Although it was a lot of work, it didn’t really feel like a job either, but more like a project where we solved each new challenge as it arose, and used our knowledge and creativity to get past them. That was definitely the most fun part of the job, Anfindsen says.

Talked with PhD students at CENSSS

Both Anfindsen and Nilsen have an interest in space research and exploration.

- I worked with one of the projects of Portal Space, the organization for students interested in space and space technology at the University of Oslo, says Anfindsen.

Portal Space is developing engines used for small launch rockets, built by the space interested students in their own time.

- There is so much in the field of robotics and automation that looks very exciting to work with for the Master’s Thesis and beyond. The space sector is one of the fields I’m interested in, because robotics and automation are so useful for space, Anfindsen says.

He applied for the summer job at CENSSS after having talked with one of the PhD students that are working with RIMFAX, and became interested in doing his Master’s degree thesis at CENSSS.

Master’s thesis work with RIMFAX

- I’ve always had an interest in space and space exploration, and participated in one of the European Space Camps for students that are held at Andøya Space, Nilsen says.

This course has students develop, build and launch their own sounding rocket as a small space project, while at the same time introducing them to the space sector as a potential field for work. The participants are also informed about what kind of studies and work experience will help them find employment in the space business.

- When I started in the Master’s degree program for cybernetics and automatic systems last fall, I saw a presentation about RIMFAX and CENSSS for Master’s students. I talked with the person doing the presentation and decided to join the center for my thesis work, Nilsen says.

Useful to work together

Initially, both he and Anfindsen were supposed to write their Master’s theses on geodata from RIMFAX in connection with machine learning. But after working with the test rover, that is likely to be a part of the students’ thesis work instead.

- The test rover can currently drive autonomously to set coordinates, but not detect or avoid possible obstacles on the way. Thus, for the test rover to become more autonomous, we would need to add some additional sensors, such as cameras or lidars, says Nilsen.

- In order to really become a test bed for future georadars in space, the rover might also need an updated or modified georadar of a similar type as RIMFAX, or maybe even an array of such radars, says Anfindsen.

This would require more work of a similar type as the two Master’s degree students have already done.

- We will most likely write individual Master’s theses, but work closely together on the practical part, as we have done this summer. It was both very useful and educational to have someone to work together with on such practical tasks, and exchange ideas and solutions with, Nilsen says.

He recommends applying for a summer job at CENSSS for all Master’s degree students who are interested in robotics and machine learning, and wish to see how this can be used in space exploration and space technology.

- It’s a perfect combination of practical and theoretical work, very varied, interesting and fun, Nilsen concludes.

Both Master’s degree students and CENSSS have decided that their thesis work will involve RIMFAX in some way, with the details to be worked out later.



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