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gaowenliang / imu_utils

A ROS package tool to analyze the IMU performance.
https://gaowenliang.github.io/imu_utils
MIT License
1.5k stars 482 forks source link

bias stability or random walk parameter #4

Open rising-turtle opened 6 years ago

rising-turtle commented 6 years ago

Hi All: By comparing the content in README with the IMU noise model described in https://github.com/ethz-asl/kalibr/wiki/IMU-Noise-Model , it seems that the parameters Gyroscope/Accelerometer "bias Instability" (in the README) are the same with the Gyroscope/Accelerometer "random walk" (in the link). Since the unit 1/(s^2*sqrt(HZ)) = 1*sqrt(HZ)/(s). Correct me if I make any mistake.

If these two parameters are the same, according to the README, the Gyroscope/Accelerometer "bias Instability" are estimated by the minimum value of the Allan variance. On the contrary, the link identifies the Gyroscope/Accelerometer "random walk" as the value of the (fitted) "random walk" diagonal (with slope +1/2) at an integration time of t=3 second. Which is the same approach used in the paper "The TUM VI Benchmark for Evaluating Visual-Inertial Odometry" (displayed by Fig. 5).

So, which is right? Any suggestion or correction is greatly appreciated, thanks in advance.

mintar commented 3 years ago

The Kalibr wiki page is right, and the code here and the documentation is wrong. Check out my fork of this repo where I fixed this and many other problems:

https://github.com/mintar/imu_utils