- January 21, 2017 at 6:24 am #6000disqzillaParticipant
First, thanks for making an excellent product. For our use case, a tiny, narrow IMU board is exactly what we needed – great!
We are mounting the board vertically, with the face on the board towards us and the ‘neck’ at the bottom. In this orientation, the -Y axis should be pointing down. However, when we read the data from the accelerometer (and use the appropriate conversion to G), it is the +X axis that has 1G of acceleration at standstill, the others around 0.
I tested this further and when applying shocks in the X and Y axes, the results look like they are swapped between these axes, and reversed. So +X becomes -Y and so on.
I am taking this from the AccX, AccY etc data directly so I don’t beleive there is a programming error. Have I made some other mistake or is this correct when working in a vertical orientation?
Thanks in advance for your help! We are doing some live experiments early next week so I hope to work this out before then if at all possible.
JürgenJanuary 21, 2017 at 12:59 pm #6003Mark WilliamsKeymaster
Hi, I assume you are using the python script berryIMU-measure-G.py?
The orientation symbol on the PCB may be a bit confusing, the accel X angle runs up and down pivot point for the gyro X angle.
I hope this image explains it better.
When the board is orientated as shown below, X should be +1 and all other values should be 0. In this
Mark --OzzMaker.com --January 21, 2017 at 9:13 pm #6005disqzillaParticipant
Thanks for the swift reply. That answers my question perfectly. As it happens, the mistake is mine – I must have accidentally referred to your title image on the website (where the axes are marked differently) rather than the one on the board (it has been tucked inside a little plastic tube so haven’t been looking at it!). May i suggest (for any other novices like me!) adjusting the title image so the axes are correct in relation to the face image? Art vs science!
I wasn’t using that python script, but a modified version of one of your others that outputs a log file of all the readings and the kalman calculations. I will be adding the G calculations you described as well.
If a force greater than the maximum G setting on the accelerometer is reached, does it just show 16, or will it give a different signal?
Thanks for your excellent support, much appreciated.
JürgenJanuary 22, 2017 at 9:32 pm #6007Mark WilliamsKeymaster
you are right.. ill get that image updated.
Sorry for the confusion.
Mark --OzzMaker.com --April 13, 2020 at 4:25 pm #15724Daniel LuParticipant
Hello Mark, I am also confused about the xyz directions on the board. Seems to me the x and z direcrion are up side down. Would you update the image indicating the correct x, y, z direction please? or where i can find the already existing correct one?
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