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PerceptIn / IRONSIDES

PerceptIn Ironsides SDK
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calibration of ironsides imu #3

Open SubMishMar opened 6 years ago

SubMishMar commented 6 years ago

Hi,

Is there any method to calibrate the imu used in this sensor system?

For one of the systems that i am currently using, the imu outputs are not that great. here is an example:

header: seq: 2913 stamp: secs: 1512616967 nsecs: 818000078 frame_id: IMU orientation: x: 0.0 y: 0.0 z: 0.0 w: 0.0 orientation_covariance: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0] angular_velocity: x: -4.44747893198e-05 y: -0.000742489297409 z: -0.00158165139146 angular_velocity_covariance: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0] linear_acceleration: x: -0.169988319278 y: -10.3573169708 z: -0.117315880954 linear_acceleration_covariance: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]

as can be seen, the z acceleration is -10.35 m/s2 . Is there a way to calibrate the device's IMU?

zzhang001 commented 6 years ago

Hi @SubMishMar first sorry for being late, we thought we covered this in one of the support@perceptin.io email threads, but just to make sure we fully understand the potential issue, is this a sequence of IMU readings when your Ironsides is still? Thanks! Also the calib file we provided has already included IMU TK and bias calibration.

SubMishMar commented 6 years ago

Hi, The device was still when these readings were taken. Yes, I know that you have already provided the calibration file. Actually, the result of visual odometry is not that bad even with these values but there is considerable drift in Z axis.

zzhang001 commented 6 years ago

If it's still and you are listing raw value, then you need to minus imu bias which we provided in the calib file. In the SLAM app, the bias correction is wrapped and not exposed, so you don't need to explicitly minus it, but if you use raw value for your own application/algorithm, then you need to minus imu bias.