By Fieke Hillerström
A few year ago, I wrote an essay about coincidence. “When people are successful, they write it to their qualities, when they fail, they blame it an accident” – C. Buddingh. The question whether coincidence really exists, is one I can’t answer. But I do know that problems with electronics are less random than they first seem. By working systematic and test as much as possible, we don’t give chance a chance.
Testing the electrical system of our car is as important as the designing. The electronics of our car are therefore tested thoroughly. Two type of tests can be distinguished, testing efficiency and testing functionality. Testing efficiency determines how many energy is gained and consumed by the electronical parts of our car. Accuracy and making the right assumptions are very important in this process. When testing functionality, the behaviour of the electronic system is tested. This is not as simple as it looks and requires a good systematical approach.
Electronics contains hardware, the small soldered parts, like you can find inside your computer, and software, the program running on the hardware. Problems can occur at both the hardware and the software. When you finished assembling the hardware, you start testing its behaviour. Do I measure the right voltages, impedances, are there any short circuit connections? When you test succeeded, the testing of the software starts, in which you go systematically through your whole program. In the end, you start testing the electronics on the solar car.
Attacking the problems
After a day of testing, you analyse all the electrical problems of the day, together with your team members. Fixing a problem, starts with analysing and reproducing the error. It is important to work systematically and therefore the situation that occurred has to be logged as detailed as possible. The datalogs of our car, help with this analysing process. Software is build out of logical steps and using enough data, you can analyse your problem systematically.
When you found a possible source of your problem, you start testing whether you really found the cause. You don’t want the situation in which you first don’t know why it doesn’t work and later on don’t know why it works again. In that case you never know whether you really tackled the problem, and still have chance to face the problem during the race. Working systematically gives us a way to solve our problems.
To eliminate all the small errors in the electronics, lots of testing is needed. Not only the normal behaviour should be tested, but also ‘monkey-proof’ tests has to be done. With these tests you look at situations that normally do not occur, but can occur by accident. Pushing multiple buttons at one time, for example, or plugging a cable inside the wrong connector. You want to know the behaviour of your car in this situations and the electronics are designed in such a way that nothing will go wrong.
During your studies you learn that even noise is not that random as it seems. Electronics is most of the time less random than you first think. By working systematically and testing a lot, we make sure we have a reliable car at the start of the World Solar Challenge.
Watch the tests with the mock-up from 2 :57!
Photos Jérôme Wassenaar and Solar Team Twente