2017 is upon us, and we’ve kept busy as usual. One of the main goals for this year has been to get a working prototype as close as possible to “the real deal”. This means being able to amplify, digitize, demodulate and transmit data over serial to a host computer. I’m happy to say we’ve managed to accomplish this, after a dash in the days between winter solstice and new year’s celebrations.
The quickly cut together video below shows how we’ve gone from a fieldmill assembly on its own, to a partially assembled cube, to the fully assembled cube in our test box. Some final screenshots demonstrate data being analyzed in LabView and GNU Octave.
The focus moving forward is making sure we only use materials which are high-vacuum compatible, to be able to do thermal tests on the design we’re currently working on. There’s also more work to be done on the simulation front, and various bits of code need to be written.Parts for a piece of calibration gear has been ordered as well, which is needed to verify that the entire analog frontend works as expected. In short, 2017 is going to be a busy year!
It’s been a while since the last update, because a lot of stuff has been happening.
On the code side, IQ demodulation is done. This has been a major task for a while, with some troubles achieving phase correctness and correct buffer handling. The working code proves that 7 MHz is enough to do demodulation for our needs. There is still some room for improvement, such as using Timer1/Timer3 input capture to get more accurate measurement of tachometer/sample times. Some optimization could also be done, if we need to increase the sampling rate (unlikely at this stage). Current CPU usage is around 60%.
We also got some new motors with built-in controllers. This reduces our work load considerably. They also have much better regulation than our previous controllers, meaning faster starting and more stable rotor speed. The electrical noise is also considerably lower and the motors run quieter.
Circuit boards for our most recent analog front end design have also arrived, and all components except the operational amplifiers we need! This may have something to do with the holiday pressure on the postal system. Hopefully they arrive before New Year’s Eve. We should also have some new toys from Atmel in the mail. More on those in a future post!
Finally, some pictures:
You are officially invited!
The Umeå Lunar Venture Innovation Fair is happening and it’s an open event for everyone. Bring your friends and come and meet the Moon Rover and hear about how we became one of the biggest space projects in Sweden.
Umeå Lunar Venture is a partnership between us (Space Science Sweden) and Umeå University. Our main goal is to put Swedens first scientific experiment on the moon in the end of next year. And as you know we are currently preparing the measuring instrument at full speed to make this happen!
The Innovation Fair is a opportunity for anyone who is interested in learning more about our work. You will get the chance to meet the Moon Rover that is taking us to the moon and it’s creators (Part-Time Scientists) who is coming all the way from Germany. And of course the students from the engineering and physics programme will be there!
Down below you can see the programme for the day and evening. Feel free to invite your friends and help us spread the word!
Attend the Facebook event here!
This week we have two major things on the electronics/instrument side of things. The first thing is we have verified that Tomas’ design with software demodulation on the AVR, fed with six channels of 24-bit ADC data, will work. There’s some bit of optimization left to do, but we should be able to dump CSV data over serial for further analysis in Octave/LabView fairly soon.
On the instrument side we have verified that choice of surface material is very important when it comes to minimizing offset fields. A consistent issue is charge buildup on aluminium surfaces due to the inherent oxide layer. Covering the surfaces with graphite reduces this charge buildup, likely because it helps in providing low-resistance paths into the bulk aluminium. Laminating the aluminium with brass foil is even better, but only the rotor has had that treatment so far. Next up is brassing all sides of the instrument.
One final thing discovered this Friday is that the offset we’re having has a phase offset compared to the desired signal by about 45°. The way the vector arithmetic works out explains the nonlinearities we’ve seen in some cases, due to only measuring the signal’s amplitude.
For some time we have been planning to have Discovery visit our lab and on Wednesday they came by. They did a report about the Umeå Lunar Venture project that will air in the near future (we will link it here). Anyway, here are some pictures from the their visit.
As some of you might already know we attended ForskarFredag a few weeks ago. ForskarFredag is an open house event for the public to attend and get inspired by science. We were there and talked about our mission Umeå Lunar Venture, the moon and the electric fields that we are exploring. Here are some photos from the day.