Hello!
I have read the documentation of the ICM-20948 IMU and done some tests, but I would like to confirm the following two points:
- The accelerometer in the ICM-20948 IMU returns values in units of g, but are these units of g-force or is it the g of free-fall acceleration? My tests and reading articles in the internet indicate it is g-force, but I wanted to confirm.
- The reference frame of the accelerometer is the same as the orientation coordinate system? That is, Y is forward, Z is up, and X is to the right for acceleration (i.e., linear translation)?
Many thanks,
Rob
Hello,
When you read the Accel data from ACCEL_XOUT_L and ACCEL_XOUT_H register, you will get a raw data that needs to be converted to unit of g. I attached a screenshot from the datasheet explains that as well.
Section 15 of the Datasheet show the orientation of the axes. I attached a picture of it here.
Hi Mustafa,
Thanks. I had seen those parts of the documents, but to me, two things are missing:
1. Should there not be a third diagram of the axes for the accelerometer? Is positive Z for acceleration upwards, like it is for orientation?
2. I understand that it is a unit of g, but is it the g of g-force (pointing upwards when standing on Earth) or free-fall g (pointing downwards when standing on Earth)?
My tests indicate that the answer to 1 is yes, it is upward like for orientation, and for 2, it is g-force. Just wanted to confirm those suspicions.
Best regards,
Rob
Hi,
Yes, you are correct. Positive Z for accelerometer is upwards. When you place the sensor as shown on the orientation of axes figure, you will read a positive 1g as g-force.
Thank you, Mustafa! That is incredibly helpful, as IMUs are something very new for me, but very cool 😊 It’s a great product
Best regards,
Rob