Guest Blog: STAR Dresden
The „Studentische Arbeitsgruppe Raumfahrt“, STAR Dresden was founded in 2018 at the University of Technology Dresden with the goal to establish a permanent platform for university students to get Hands-On-Experience in space projects. Since then, we participated in the “European Space Elevator Challenge” and successfully launched two experiments onboard the “BEXUS” balloon in northern Sweden. The group has about 35 members.
Beside other ongoing projects one team worked on a Mars Rover that participated in the “European Rover Challenge” 2021 in Poland. The rover ELECTRA had to compete in several tasks in a mars-like terrain, called “mars-yard”, against 13 other student teams from around the world. The tasks include simulations of various real-life situations, while the team takes the role of operators on a remote control-station.
This year the rovers had to traverse challenging terrain. Other tasks included picking up probes with the onboard arm, excavating and taking pictures as well as drilling and taking soil samples. One separate task was the manipulation of a switchboard.
For an in-depth report visit our website at https://star-dresden.de/european-rover-challenge-2021/
Since it was our first time in the competition, we faced many challenges and were not able to solve all the tasks. One of the biggest challenges was the differential gear in the center of our rover. It broke while preparing for the competition and we could not fix it in time. Therefore, we could not carry our arm during the main task. Even with this setback, we were able to maneuver our way through the mars-yard to reach our marked spots. Unfortunately, at one point we lost communication and the rover drove on its own into the biggest crater. But thanks to its great mobility he could free itself without taking damage. We also found water on the mars-yard at the bottom of this crater, which gave us some extra points!
On the switchboard the grabbing mechanism got stuck so we could not open or close our grabber. This reduced our capabilities to only flicking switches. It worked but was hard enough.
One of the things that worked flawlessly were our motors and their drivers. In total we used 21 stepper and eight BLDC motors. To control them we developed two Stepper Control modules, built around Trinamic Stepper Driver ICs: the TMC-5130 for low currents like the camera gimbals and the TMC-5160 for high currents like in the biggest motors of the robotic arm. We also used the TMCM-1640 BLDC Driver from Trinamic for drive and steering. Trinamic´s well-documented, efficient, and easy-to-use ICs make implementation and development as fast as possible. It was no problem to design the modules based on their documentation and in retrospect we would choose those drivers again. In the future we hope to further expand our usage of the drivers to use their full potential.
To reduce development time and costs for our projects, STAR internally develops modularized Circuit Boards that each serves a special purpose like motor control, current measurements, or battery protection. These modules can be stacked and placed on a tiny Computer like an Arduino or Raspberry Pi. Several of these stacks controlled the sub-assemblies of the rover. This way we can individually test single assemblies like the arm without the whole rover. This also enables us to build our own ecosystem of already build, programmed and tested electronics, that future students can use and learn upon.
After two years of development and a lot of work we are happy to achieve a very good fifth place in the ERC 2021. Especially considering that about 60 teams initially applied of whom only 14 were accepted and could participate on-site and many of them did so with a lot more experience.
October 21, 2021 / Anna Höhling / 0