This forum uses cookies
This forum makes use of cookies to store your login information if you are registered, and your last visit if you are not. Cookies are small text documents stored on your computer; the cookies set by this forum can only be used on this website and pose no security risk. Cookies on this forum also track the specific topics you have read and when you last read them. Please confirm whether you accept or reject these cookies being set.

A cookie will be stored in your browser regardless of choice to prevent you being asked this question again. You will be able to change your cookie settings at any time using the link in the footer.

Finding accelerometer location inside a phone
Here are some accelerometer position results from the data shown previously. First the geometry and calculation of accelerometer position is shown below. 
Photo of the actual setup.
Alignment of the phone x axis and turntable x axis is done by placing the center of the phone's right side against the spindle. 
   The position calculated using accelerometer, accelerometer minus bias and linear acceleration data did not agree so an alternative method of measuring accelerometer position was used for comparison. This other method I'm calling the “null method” and involves varying the phones position on the turntable until the Ax and Ay readings go to zero while the turntable rotates. Because the spindle is in the way for free positioning of the phone, the phone is placed on a small platform above the spindle. The null method setup is shown here.
The remote control feature of Phyphox came in very handy for this because I could start recording data after the turntable got up to full speed. With no startup transients on the graphs the scale of the plots remained small and I could clearly see the mean of Ax and Ay getting close to null. Once null was established a felt marking pen was used to trace circles on the glass cover of the phone. These marked circles allow the center of rotation and hence the accelerometer position to be measured.
Here is the accelerometer minus bias null position.
A table of the results.
The largest difference between the calculated position and the null position was seen in the linear acceleration with 1.6 cm, accelerometer was 3 mm and accelerometer minus bias was about 2 mm. Of course these results will probably vary with the type of phone.

Messages In This Thread
RE: Finding accelerometer location inside a phone - by Haversin - 01-22-2020, 01:31 AM

Forum Jump: