Technical reference says that the 3-axis values from the accelerometer and gyroscope sensors on the MKR IoT Carrier can be retrieved and stored in float variables. They have x,y,z directions.
For the accelerometer, what is the direction of positive x,y,z with respect to the plane of the carrier's display??
Is there a diagram of directions in (1) above shown on the carrier??
Is there a diagram on how the rate of rotations are measured by the gyroscope with respect to axes x,y,z ?? Do the rate of rotations by the gyro have positive/negative directions??
Thanks. AA
I checked the carrier's cheat sheet, the data sheet and the product reference manual. None of them show how the axes are positioned on the carrier. They all repeat the same: 3-axis accelerometer or 3-axis gyroscope but the coordinate/axes system is conspicuous by its absence.
From the LSM6DS3 data sheet it is absolutely clear how the axes are oriented:
However, it is easy enough to figure out where IMU sensor axes are pointing.
When the accelerometer is held still, it will measure an acceleration of 1 g along the positive direction of any vertical axis. Usually Z will be perpendicular to the plane of the PCB.
Similar methods can be used to identify the magnetometer axes. The Earth's magnetic field points North and in the northern hemisphere, rather steeply Down.
Thank you again. I am using the MKR IoT Carrier (see picture ), which houses the accelerometer. My issue is that the values I get statically for pitch = asin(a_x/g) are OK. But the results for roll = atan(a_y/a_z) are orders of magnitude off. When I print the values for pitch and roll, they do not coincide with the axes you show. Hence, I am looking for how the axes are positioned on the actual carrier.
Either the code is wrong, or you did not identify the axes correctly.
Print the raw accelerometer values to verify axis orientation. Make sure that you have correctly identified the sensor chip orientation by locating the dot on the package.
It is guaranteed by ST that the chip markings and sensor axes will match the drawing in the data sheet, which, incidentally, is a legally binding document.
The MKR IoT Carrier provides axis directions typically related to orientation: X refers to horizontal movement, Y denotes vertical movement, and Z indicates depth or forward-backward direction. These directions are vital for understanding sensor readings and positioning in IoT projects.
Surprising that Arduino has not, as far as I know, published a single diagram with the actual system of axes used on the MKR IoT Carrier. Even for the MKR IoT Carrier rev 2 there is no clear identification of how the 3 axes are positioned with respect to the actual carrier (not with respect to the accelerometer). I wish Arduino Tech jumped in on this topic...
), which houses the accelerometer. My issue is that the values I get statically for pitch = asin(a_x/g) are OK. But the results for roll = atan(a_y/a_z) are orders of magnitude off. When I print the values for pitch and roll, they do not coincide with the axes you show. Hence, I am looking for how the axes are positioned on the actual carrier.