The accelerometer is placed horizontally and the data is not read correctly.

emily_1105

The accelerometer is placed horizontally and the data is not read correctly. [Copy link]

 

When the ADXL355 accelerometer is placed horizontally, the theoretical readings of the X-axis and Y-axis data should be 0g, and the Z-axis data should be plus or minus 1g, but now I can't get such data. I want to calibrate it, but when I change different angles in the horizontal plane and read the acceleration values output by the XY axis of the accelerometer, I find that the deviation is large. The data is as follows:

X =1,Y=17; //After the first movement, the data measured in the static state

X=15,Y=36;//After the second movement, the data measured in the static state

X=-2,Y=52;//After the third movement, the data measured in the static state

Please help me analyze whether this is correct?

If an offset value is written, how should it be selected? If multiple measurements are taken to get the average, will the error also be large enough?

dcexpert

It feels like the data read is incorrect. Under normal circumstances, the consistency is good, the deviation is not too large, and there will only be a small range of fluctuations

freebsder

Convert it to g and see that the original value has a jump anyway

littleshrimp

Are the values of X and Y the original data read from the register?

The sensor itself will have some noise. You can check the data sheet to see if the actual noise is within the range.

In addition, it is difficult for an individual to achieve an absolutely horizontal plane, and the sensor will also be affected by external vibrations, which all need to be considered.

emily_1105

dcexpert posted on 2020-4-13 11:43 It feels like the read data is wrong. Under normal circumstances, the consistency is good, the deviation will not be too large, and there will only be a small range of fluctuations

emily_1105

littleshrimp posted on 2020-4-13 12:24 Are the values of X and Y the original data read from the register? The sensor itself will have some noise. You can check the data sheet to see the actual noise...

emily_1105

freebsder posted on 2020-4-13 11:57 Convert it to g and see that the original value has a jump anyway

emily_1105

This is the data read

littleshrimp

emily_1105 published on 2020-4-13 14:48

It seems that there is no component of gravity acceleration in your data. Are you sure the data you read is accurate?

dcexpert

emily_1105 published on 2020-4-13 14:47

The data range is not that large. Generally, the accuracy of accelerometers is only 10-12 bits.

emily_1105

dcexpert posted on 2020-4-13 15:48 The data does not have such a large range. The accuracy of general accelerometers is only 10-12 bits.

ADXL355 is a 20-bit register

emily_1105

littleshrimp posted on 2020-4-13 15:33 It seems that there is no component of gravity acceleration in your data. Are you sure the data you read is accurate?

The data of the XYZ axes are all read directly from the registers and read out via I2C.

yichun417

The surrounding environment and people walking by will affect the reading results.

littleshrimp

emily_1105 posted on 2020-4-13 16:17 The data of the XYZ axis are all read directly from the register, read out by I2C.

Check who am i to eliminate communication problems

emily_1105

littleshrimp posted on 2020-4-13 16:47 Check who am i to rule out communication problems

What does who an i mean?

emily_1105

yichun417 posted on 2020-4-13 16:40 The surrounding environment and people walking by will affect the reading results.

It is simply placed on the desk, with people around. The desk does not move.

amaoge

It seems that there is a problem in converting the value from the XYZ register to G unit value.

yichun417

emily_1105 posted on 2020-4-13 16:59 It is simply placed on the desk, and there are people around. The desk does not move.

Then your level data is not of reference value.

littleshrimp

emily_1105 posted on 2020-4-13 16:53 What does who an i mean?

A register of the sensor can determine whether the communication is normal

dcexpert

emily_1105 posted on 2020-4-13 16:16 ADXL355 is a 20-bit register

If it is high-precision, then the data is fine. Look at the data manual to see if there are requirements for reading timing, whether the data conversion is completed, parameter settings, etc. Since the register data can be read, there should be no problem.