Question

Hello,

I am attempting to control a tracked robot through ROS using the gazebo-9 plugin 'libSimpleTrackedVehiclePlugin.so'. I am having a bit of an issue finding any sort of concise documentation for implementation of this plugin, other than the 'trackedvehiclesimple.world' example implementation, which does not implement ROS control. I do not think there is an implementation difference between gazebo-9 and gazebo-11 but I may be mistaken. I have a few ROS Melodic dependencies in my codebase that requires I use gazebo-9 for compatibility through the current recommendations.

In the example implementation the plugin is initiated with the following code.

        <plugin filename="libSimpleTrackedVehiclePlugin.so" name="simple_tracked_vehicle">
            <body>base_link</body>
            <left_track>left_track</left_track>
            <right_track>right_track</right_track>
            <left_flipper>front_left_flipper</left_flipper>
            <left_flipper>rear_left_flipper</left_flipper>
            <right_flipper>front_right_flipper</right_flipper>
            <right_flipper>rear_right_flipper</right_flipper>
            <track_mu>2</track_mu>
            <track_mu2>0.5</track_mu2>
        </plugin>

        <plugin filename="libKeysToCmdVelPlugin.so" name="keyboard_control">
            <publish_as_twist>true</publish_as_twist>
            <cmd_vel_topic>~/simple_tracked/cmd_vel_twist</cmd_vel_topic>
        </plugin>

I have a bit of confusion on a few key aspects of this implementation. First, my implementation does not have any "flippers" and I am unsure of how integral these flippers are to this plugin. Are they optional? Second, the drive options that have built in ros support such as 'libgazeborosskidstreerdrive.so' allow for the command and odometry topic configuration using the and tags. I would like to do something similar with this plugin, but am unsure of the workflow. Would this be possible using xacro/sdf configurations or would it require editing the .cc .hh source code and compiling a modified version of the plugin? I am interested in learning how to code customs plugins, but I don't quite have a strong enough grasp on the codebase and .sdf interaction in the plugins in order to start. I know gazebo tutorials have some resources, but I would appreciate some guidance or insight to the gazebo development learning process. I have some future implementations that would require me to learn this eventually anyways.

In particular, I could use some insight into how to properly implement the transport library for use with ROS. I think that I may understand from comparing the .cc source code for track systems vs diff drive/skid steer differences, but some additional guidance that doesn't come from me attempting to reverse engineer code would be nice. I can't find documentation on the tutorial site for it, but I may be missing something.

Thank you in advance,

Grant

Asked by gmetts on 2020-12-03 11:10:33 UTC

libSimpleTrackedVehiclePlugin.so ROS support workflow

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