I haven't been following this thread carefully, but understand that your average is not working out. Have you taken the unit in your hand and shaken it all about and then returned it to its original location *and* kept the orientation of the unit the same during that motion? If you integrate the x, y and z accelerations independently, you will get x,y,z velocities and if you integrate the velocities you get x,y,z displacements. Do those make sense? If not, you likely have a problem wit= h your algorithm. Hand motion should be << 6G. There are different ways to do numerical integration, some more accurate than others. For short period= s of shaking, say 1 sec, your velocities and displacements should return to something close to zero. If you want to provide some isolation for your accelerometer you need to find a soft flexible material that will allow movement in all axis. Clamping a circuit board with a rubber washer with a screw is not going to cut it. Try some *small* pieces of thick double sided foam tape. This won't remove the higher frequencies, just attenuate them like an electronic filter. Gordon Williams ----- Original Message -----=20 From: "Electron" To: "Microcontroller discussion list - Public." Sent: Thursday, June 21, 2012 4:40 AM Subject: Re: [EE] Weird MEMS accelerator behavior? > At 22.04 2012.06.20, you wrote: > >> In answer to other messages, the accelerometer I'm using is +/- 6g on all > >> 3 axis, I don't think it's clipping anymore (it was when it was +/- 2g ), > > > >That's still pretty slim margin. Acceleration is deceptive. > >Can you mount a temporary unit with more like a 20G range, to confirm > >that you aren't seeing larger events? > > I have some 10g accelerometers and I will mount them when I make new boards, > i.e. when the PCB manufacturer sends them (2 weeks? as I haven't sent the order > yet because I have to spend some days updating some other parts), the one I'm > currently using is already potted in epoxy and I cannot rework it. I had made > this PCB by hand but with PTH components which need both sides soldered and > offer physical access only to the bottom side, it's a nightmare (to solde= r the > connector for example I had to bend all the pins to gain access to the to= p side, > then re-bend each, and so on. With the cap the height was 1mm too high an= d I had > to invent other things to overcome the lack of PTH, the board was generally not > easily solderable, etc.. a nightmare when you try to make a professional (0403 > components, QFN, etc..) PTH prototype board by hand). > > > >I had a project where we were doing somewhat worse things to the PCBs, > >but we were able to get the events DOWN to 2000G, with carefully > >designed Norsorex dampers. We also had to pay careful attention to > >mass distribution on the PCB so that we didn't flex much during those > >events. > > The original ECU alredy used silent blocks (just thick rubber washers), and > that's what I'm using too. I wonder if there's some better way to damp th= e > vibrations, but I cannot use any extra mm of space than the original uses= , > and it's mounted on a small plate which flexes. A question: what is more > rigid, a 1mm thick plane of aluminium or steel? Is there any rigid material > which will damp vibrations? Or is it even a contraddiction in terms? > > > >--=20 > >http://www.piclist.com PIC/SX FAQ & list archive > >View/change your membership options at > >http://mailman.mit.edu/mailman/listinfo/piclist > > --=20 > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .