SunSPOT Meteorological Station

Two students at Lucerne University of Applied Sciences and Arts built a meteorological station with SUN Spot technology. This was a prove of the interdisciplinary cooperation we wrote on our banner @ HSLU T&A. Our parallel programming and virtual worlds expert Roger Diehl guided the students through their term paper. I cannot give enough regards to Prof. Fritz Rothenbuehler from the Mechanical Engineering department. He helped designing the body and mechanics, he draw the CAD and made it real with the 3D Plotter. All without any bureaucratic overhead. Also thanks to Markus Provini for his help with mechanical parts. Note: There where other departments which did not the slightest thread without filling a blank for this and then another form for that and of course the main form for how to pay….

Read how they did it:

Our task was to build a meteorological station, which can measure weather relevant data. Therefore we had to use SunSPOT technology. Both wind speed and wind direction had to be determined by using the acceleration sensors on the SunSPOTs. Further we had to detect the temperature, humidity and light intensity.

This project had differing aspects which we had to tend to. Firstly we had to familiarize ourselves with the SunSPOT technology. Secondly we had to figure out how to use the accelerator sensors to measure the wind speed as well as the wind direction. And last but not least we needed to build the meteorological station.

All aspects combined made this adventure quite challenging, but we were soon enthusiastic about the possibilities using SunSPOT technology. In a short amount of time we were able to read the accelerations sensors, thanks to the demo program. Thus we were able to go through a few test scenarios which helped us to find a solution to the wind problem. We decided to imitate the idea of a wind wheel and were therefore able to determine the centrifugal force of the corresponding rotation speed.

For the wind direction though, this didn’t work quite as easily. By the fact that the acceleration sensor constantly affects the force of gravity, it is possible to determine the absolute position of a SunSPOT Client. The only issue was that the axes of the sensor were pointing in the wrong direction to make this work. We agreed upon using a weather vane to determine the wind direction but this hasn’t yet solved the axes problem. So we came up with the idea of redirecting the rotation on another axis. It is now possible to use gravity to find the current wind direction.

A few points still remained open. a SunSPOT client does not come with a humidity sensor so we had to find a suitable sensor ourselves. Fortunately we found a blog where someone had already done this before. This showed us that it was possible and we were confident in our choice. Sensirion SHT71 was the sensor we used to measure the external temperature and humidity. The light intensity can be detected with the onboard light sensor. Finally we transmitted the battery lifetime and internal chip temperature as well.

The big question mark surely was the construction of the meteorological station itself.  Our team consisted solely of two IT students, so we lacked the necessary know-how for the construction side. Fortunately we could rely on the support of several different departments at the university. Our concept was visualized in Cinema4D and together with the mechanical department, the meteorological station finally became reality.

But this wasn’t the end of the story. Every machine has to be calibrated and this was the case with our meteorological station too. At the University of Applied Science Lucerne we have our own wind test facility. Therefore we were able to achieve an exact calibration of our machine which resulted in an error of measurement of only 1%.

In our opinion the project was a total success. Its challenging tasks and the new insights it brought us made us glad to be part of this adventure.

Mike Bloechlinger