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cyberbotics / webots_ros2

Webots ROS 2 packages
Apache License 2.0
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Problem about coordinate system #224

Closed BruceXSK closed 3 years ago

BruceXSK commented 3 years ago

I use the DeviceManager to manage the devices on my robot, include a Velodyne VLP-16 lidar. The default coordinate system of Webots is NUE but the ROS is ENU. So there is some trouble with the PointCloud data. I revised the "coordinateSystem" of "WorldInfo" to "ENU". And revised the xyz order of PointCloud2 message in cloud data publish function of webots_ros2_core/devices/lidar_device.py as:

msg.fields = [
    PointField(name='y', offset=0, datatype=PointField.FLOAT32, count=1),
    PointField(name='z', offset=4, datatype=PointField.FLOAT32, count=1),
    PointField(name='x', offset=8, datatype=PointField.FLOAT32, count=1)
]

This will solve the problem for now. But I still wonder if there is a general practice to solve this coordinate system transformation problem. Thanks a lot

lukicdarkoo commented 3 years ago

ENU is actually a coordinate system of the world and it is independent of FLU (Forward, Left, Up), a convention used for ROS robots.

Unfortunately, at the moment, we don't have a cleaner solution. However, we are slowly converting all PROTOs to FLU. Our plan is to have all PROTOs (including robots, objects, and devices) use the FLU convention.

BruceXSK commented 3 years ago

ENU is actually a coordinate system of the world and it is independent of FLU (Forward, Left, Up), a convention used for ROS robots.

Unfortunately, at the moment, we don't have a cleaner solution. However, we are slowly converting all PROTOs to FLU. Our plan is to have all PROTOs (including robots, objects, and devices) using FLU convention.

I've got it. Thank you