I must admit that watching him slowly get more and more desperate with his bug fixes has been rather amusing, but we have come to the conclusion that there are certain error sources that cannot be counteracted by software. The two big sources that we could deduce was excess electromagnetic noise from the car motor causing the accelerometer to act weirdly, and extra vibrations in the stack of electronics the accelerometer was attached to leading to the accelerometer experiencing accelerations on top of those experienced by the car.
My helpful contribution has been to design and build a superstructure to fit on top of the preexisting chassis with measures to reduce both of our sources of error. This involves creating a rigid structure to try and keep the accelerometer fixed relative to the chassis, and adding shielding to our two main sources of EM noise, the motor and contact brushes.
A quick session with the laser cutter later and I had most of my structure ready to be glued together ( I have decided that the laser cutter is by far my favorite tool up in the workshop, so quick, so precise and straight out of a spy movie). There was also a piece of scrap metal available of exactly the right width and thickness, so the metal plating was also fairly straightforward to make.
The result is not fancy, but it looks much cleaner than the mess of tape and haphazard stacking that it replaces and should definitely work as an initial solution to some of out problems.
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| The 'completed' superstructure. I think it looks a bit like a campervan! |
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| MDF structural elements, laser cut |
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| Metal plates to cut EM noise, at about 1 mm thick they are massively overkill as aluminium foil would likely do just as well. While cutting and measuring the pieces I was asked if I was building a tank! |
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