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How to interpret the Accelerator raw data in HDL-32E?

asked 2013-10-25 09:16:45 -0600

MinaAttari gravatar image

updated 2014-01-28 17:18:21 -0600

ngrennan gravatar image

Hi, We have a Velodyne Lidar (HDL-32E)(equipped with IMU) that I am trying to start with it. we have gathered UDP positioning packet(port 8308) which includes gyroscope, accelerometer and temperature measurements. I have a few questions:

1- Should all gyro measurements be negative? (mine are)

2- We get 6 accelerometer measurements (ACC1x, ACC1y, ACC2x, ACC2y, ACC3x, ACC3y). I expected to have 3 acceleration measures. How can I get these 6 to 3 x-y-z accelerations?

3- We get 3 temperature measures? why 3? do they differ?

I really appreciate your help.

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I have no access to that device and no experience with it. Maybe others can help.

joq gravatar imagejoq ( 2013-10-25 12:51:29 -0600 )edit

Appendix B in the 32E manual does have some diagrams and hints: http://velodynelidar.com/lidar/products/manual/63-9113%20HDL-32E%20manual_Rev%20E_NOV2012.pdf .

joq gravatar imagejoq ( 2013-10-25 12:52:54 -0600 )edit

I have the same question 2, how can I get the 3 x-y-z accelerations from these 6 measurements? You already figured it out?

Michiel gravatar imageMichiel ( 2014-07-28 06:48:14 -0600 )edit

In order to get the orientation and accelerations out of these 6 measurements, you should use some IMU algorithm. For example this: http://dx.doi.org/10.1155/2015/503814 and it has source code available here: https://github.com/hhyyti/dcm-imu

Heikki gravatar imageHeikki ( 2015-12-04 03:17:58 -0600 )edit

Note: there is now an experimental velodyne_gps_imu package in github. It's currently in the gps_imu branch, not yet merged into master. Anyone who tries it, please comment on pull request #53

joq gravatar imagejoq ( 2015-12-04 14:48:14 -0600 )edit

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answered 2014-07-28 13:02:02 -0600

ahendrix gravatar image

Figure B2 on Page 18 of the manual that @joq linked shows the orientation of the accelerometers and gyros.

The manual also notes "Note: Each gyro incorporates a 2-axis accelerometer which results in redundancy in some axial directions"

From all of that, it sounds like they're using three separate gyroscopes internally, each of which probably has its own temperature sensor for calibration.

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Asked: 2013-10-25 09:16:45 -0600

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Last updated: Jul 28 '14