The European Space Research and Technology Centre (ESTEC), the technological heart of ESA, recently brought in an extraordinary number of PDEng trainees to work on an important research project. These 14 trainees are all part of the two-year post-master Software Technology PDEng program, organized by Eindhoven University of Technology. Their assignment? To make three drones – quadcopters modelled with TASTE, ESA’s open-source toolset for model-driven software design – fly in formation.
Simultaneously controlling several Unmanned Aerial Vehicles (UAVs) may not initially sound relevant for space missions. But nothing could be further from the truth. Many of the next-generation space missions rely on multiple spacecraft working closely together. For example, for LISA, the Laser Interferometer Space Antenna: three space crafts that are going to fly in a triangular formation separated by 2.5 million kilometers. They will be bouncing a laser beam between them in order to detect gravitational waves. Or the two parts of the Proba-3 spacecraft, which need to be able to communicate while performing a very accurate formation flying mission to observe the corona of the Sun. In short, these PDEng trainees are doing their part to make future space missions a success.
Complex set of algorithms
It may seem a little overkill, 14 PDEng trainees for a formation flight of only three drones. But Dr. Yanja Dajsuren, program director of the Software Technology PDEng program, ensures us that it is not an easy task: “A quadcopter has four propellers, which are controlled by separate motors and a complex set of algorithms. It is challenging to make the quadcopter fly steady enough to allow formation flying.” For that reason, trying to make the quadcopters fly was not the first step of the project. It all started with a training day at ESTEC, to master modeling with TASTE. Marcel Verhoef, ESTEC software engineer: “Usually, we invite individual students and young graduates to ESTEC, to introduce a new generation of engineers to our field of work. But for this project, with a multidisciplinary nature, we were interested to see what a group of trainees could accomplish in a short time.”
From five to three quadcopters
In the weeks after the training, the trainees worked in sprints on system design, simulation, prototypes and the positioning system. These sprints helped them develop their technical skills. Dmitriy Kondrashov, PDEng trainee: “As a project manager, I also learned how to smoothen the work process, create a good work environment and establish a strong connection between our team and ESA. That was very valuable.” The trainees started out with five drones, but quickly discovered that many factors can affect their stability. For instance, the remaining battery power has an impact on the maximum acceleration of the propellers. Some of these properties had to be discovered through trial and error, which was reflected by the state of the equipment. Dajsuren: “We started the project with five quadcopters plus spare parts. After eight weeks, only three of them were left...”
At the end of the project, the trainees presented their results to the staff of the ESTEC Software Systems Division. The PDEng trainees managed to make the three drones fly in formation, and even demonstrated this on the spot. Verhoef: “The goal we had set was very ambitious. It was difficult to estimate in advance how far the trainees would get, given their limited time. Having the quadcopters fly in formation within eight weeks is a great achievement. We are very happy with the trainees’ efforts.” Dajsuren: “Our PDEng programs prepare trainees for an extraordinary career in industry. But even during their studies, these trainees can already be of real value to organizations, by working on real-world projects.” Next up for ESA: a demonstration of the three flying quadcopters during the ESTEC open days.