M8 lidar about lidar_body_tracking

[MyNameIsCosmo]

Try adjusting the values in the Dynamic Reconfigure starting with the filtered cloud and cluster sizes.

Also check the output of the lidar_body_tracking node in your terminal. You may need to pass --screen to the end of your roslaunch command.

[yashspatel09]

Hey I know I am not helping you much with this info but I am new with ROS and trying to figure out what I am doing wrong. Please guide me through this. This image shows 2 files that needs frame id change and 2 terminals with roslaunch and rostopic. For some reasone QP308 is still displaying and there is still no data in filtered or clustered nodes.

Can you please walk me through this. I would be really thankful

[MyNameIsCosmo]

In the lidar_body_tracking.launch (top-left) try changing scan_topic to /QP308/pc_QP308

/QP308/pc_QP308 is the Point Cloud topic published by the Quanergy Lidar driver.

Welcome to ROS!

[yashspatel09]

Yup in my case it is Sensor/points

[MyNameIsCosmo]

Can you do a rostopic info on both:

• /QP308/pc_QP308
• /Sensor/points

[yashspatel09]

left bottom is rostopic list after running Quanergy ros driver only and right bottom is after running lidar_body_tracking roslaunch

So I believe QP308 is coming from roslaunch. Please check following screenshots. Left side is /Sensor/topics and right side is /QP308

[yashspatel09]

Again I am sorry for troubling you so much

[MyNameIsCosmo]

The frame_id in the topic is set to Sensor.
The URDF robot_name should be set to the same frame_id as the topic:
https://github.com/MyNameIsCosmo/lidar_body_tracking/blob/master/urdf/m8.urdf.xacro#L2

Try changing name="sensor_m8" to name="Sensor"

[yashspatel09]

do I change macro name as well? ( <xacro:macro name="sensor_m8">)

[MyNameIsCosmo]

Nah, the macro name is irrelevant to this issue.

In fact, the macro is redundant for the Xacro file and is confusing, but that's an issue for a later date.

[yashspatel09]

Well something silly mistake is been getting on for sure/

[MyNameIsCosmo]

I derped

The actual value you need to change in the urdf is the link:
https://github.com/MyNameIsCosmo/lidar_body_tracking/blob/master/urdf/m8.urdf.xacro#L8-L10

      <child link="Sensor"/>
    </joint>
    <link name="Sensor">

[yashspatel09]

<?xml version="3.0"?> <robot name="Sensor" xmlns:xacro="http://ros.org/wiki/xacro"> <xacro:macro name="sensor_m8"> <link name="base_link"/> <joint name="m8_joint" type="fixed"> <origin xyz="0 0 0" rpy="0 0 0"/> <parent link="base_link"/> <child link="Sensor"/> </joint> <link name="Sensor"> <visual> <origin xyz="0 0 0" rpy="0 0 0"/> <geometry> <cylinder length="0.0876" radius="0.10315"/> </geometry> <material name="dark_grey"> <color rgba="0.3 0.3 0.3 1"/> </material> </visual> </link> </xacro:macro> <sensor_m8/> </robot>

[yashspatel09]

I did changed it to Sensor much before

[yashspatel09]

Can it be possible that it height might be the reason? I can try placing it higher if needed

[MyNameIsCosmo]

Height shouldn't be a reason since height should remain independent of the data.

Try putting some debug info like ROS_INFO('cloud_cb') into the cloud_cb function, and work your way from there.

Few things to check are:

• frame_id of your sensor topics (use rostopic echo -n1 /Sensor/points/header/frame_id)
• link in the urdf is the same as the frame_id
• there is a pointcloud from the sensor and the dynamic reconfigure settings seem reasonable (you may have to play with cluster sizing, but the defaults worked for the m8 I had)
• There are no clashing roslaunch files (rospack find lidar_body_tracking should bring up the current catkin workspace you're working with)

[yashspatel09]

Okay. Just one more thing before I do debugging. What should be the output for pcl_clustered and pcl_filtered when you do rostopic echo pcl_clustered/filtered

[MyNameIsCosmo]

They should look like the same pointcloud message from Sensor/points except with less data

[yashspatel09]

Alrighty. Let me give it a try and see if anything works for me. I will ping you with result once I am done.
Thanks once again