# Axis conventions

Hi everybody, I need some clarification on the axis orientation convention used in the package robot_localization. I am pretty sure answers will be profitable for everybody as this is giving me headeach. For acceleration of Imu , the wiki says :

Imu neutral, Measure +9.81 meters per second squared for the Z axis.

If the sensor is rolled +90 degrees (left side up), the acceleration should be +9.81 meters per second squared for the Y axis.

If the sensor is pitched +90 degrees (front side down), it should read -9.81 meters per second squared for the X axis.

I understand, that in local frame:

x up
y right
z down


But according to the REP 103:

In relation to a body the standard is:

x forward
y left
z up


At least, i understand that for magnetometer which is related to "short-range Cartesian representations of geographic locations" of REP-103:

X east
Y north
Z up


1) Is it correct that odom/map frame (for magnetometer, barometer) have a different axis convention than local frame (for accel, gyro). 2) Am i misunderstanding the conventions used, or there is a mistake on the wiki ?

I have drift issue on the orientation, and i think it is related to some conflict between sensors. Here is the conventions of my IMU (It seems to be reversed ...):