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IMU quarternion output interpretation?

asked 2016-05-09 23:30:44 -0600

dmngu9 gravatar image

Im a bit confused about the quarternion output of IMU. By what i understand, the gyroscope measure the angular rate of change in deg/s right? Lets say i got an object move from position A -> B ->C. Should the output at C be the angular change compared to that at position B? How the output of IMU in ROS gives quarternion.?

Lets say at C, i have output of quarternion X and at D , i got quarternion Y. If i just get XY, i will get the total rotation . Is that right?

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answered 2016-05-10 02:04:39 -0600

Mehdi. gravatar image

updated 2016-05-10 02:05:27 -0600

If you check the IMU message type defined by ROS, you can see that it has three main elements. Linear velocity, angular velocity and orientation. The angular velocity is the one expressed in rad/sec containing three values for three axes. Only the orientation is expressed in Quaterions and when you transform it to Euler angles, it represents the rotation around the three Cartesian axes, which means it is a pose information and not velocity (where the z axis is probably the opposite gravity direction and the x and y axes are initialized at the beginning). It is not a good idea to try imagining or visualizing quaternions as it is impossible (At least for the average human being). Here is a nice video about them. The best thing to do is to get Rviz to display your IMU message.

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Asked: 2016-05-09 23:30:44 -0600

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Last updated: May 10 '16