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navsat_transform_node without IMU

asked 2019-07-29 08:27:43 -0500

levi.starrett gravatar image

I'm trying to fuse GPS data and IMU data using robot_localization. I have the IMU data going into the filter nicely, now I'm trying to configure GPS. The problem is that my robot has a large inverter relatively close to where the IMU is mounted which is causing too much magnetic noise, so the magnetometer on the IMU is disabled. I understand that the navsat_transform_node requires an absolute starting heading (usually from the IMU) to initialize properly. What are some ways I can get around this?

I thought about enabling the "wait_for_datum" parameter and then using the GPS to manually using the set_datum service. Has anyone done this in the past?

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answered 2019-08-29 04:32:19 -0500

Tom Moore gravatar image

navsat_transform_node only needs one IMU message to generate the required transform, so one option is to make a node that waits until your robot has driven X meters, and then uses the relative poses of the start and current GPS readings to generate an earth-referenced heading. Then you can publish that as a quaternion in an IMU message.

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Just wondering if anyone else has had any success with this technique.

w_botics gravatar image w_botics  ( 2022-11-29 21:56:59 -0500 )edit

Crazy behavior I have spent hours trying to see the /imu topic being subscribed by navsat_transform_node and nave saw it! Then quickly echoing the /imu topic in subsequent seconds, I checked this behavior:

new_nav2_ws$ ros2 topic info /imu
Type: sensor_msgs/msg/Imu
Publisher count: 0
Subscription count: 2

new_nav2_ws$ ros2 topic info /imu
Type: sensor_msgs/msg/Imu
Publisher count: 1
Subscription count: 1

the navsat_transform node consumed once the imu data and unsubscribed (the counter fall from 2 to 1)

Vini71 gravatar image Vini71  ( 2023-08-08 16:23:46 -0500 )edit

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Asked: 2019-07-29 08:27:43 -0500

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Last updated: Aug 29 '19