Write a tutorial about using transport parameters with systems

[scpeters]

Desired behavior

A new feature was added in https://github.com/gazebosim/gz-transport/pull/305 to declare and use parameters. An interface to this functionality was added for gz-sim systems in https://github.com/gazebosim/gz-sim/pull/1431, with a demo in the parameters-component-wheel-slip-demo6 branch and https://github.com/gazebosim/gz-msgs/commit/e19f8e5dddd27106ef874cccd38590b65acd81f0. This demo should be merged to a release branch along with a tutorial.

Alternatives considered

Implementation suggestion

Demo instructions from #305:

Steps to run the demo:

• Build from source ignition fortress checking out the two branches specified above (I can provide PRs for another version if needed).
• Launch the trisphere cycle world:

  ign gazebo trisphere_cycle_wheel_slip.sdf
  

• In another terminal with the workspace sourced:

  • List available parameters:

    ign param -r /world/wheel_slip -l
    

    Expected output

    systems.wheel_slip.trisphere_cycle1.wheel_front [ignition.msgs.WheelSlipParameters] systems.wheel_slip.trisphere_cycle1.wheel_rear_right [ignition.msgs.WheelSlipParameters] systems.wheel_slip.trisphere_cycle0.wheel_rear_right [ignition.msgs.WheelSlipParameters] systems.wheel_slip.trisphere_cycle1.wheel_rear_left [ignition.msgs.WheelSlipParameters] systems.wheel_slip.trisphere_cycle0.wheel_rear_left [ignition.msgs.WheelSlipParameters] systems.wheel_slip.trisphere_cycle0.wheel_front [ignition.msgs.WheelSlipParameters]

  • Get the systems.wheel_slip.trisphere_cycle1.wheel_front parameter:

    ign param -r /world/wheel_slip -g -n systems.wheel_slip.trisphere_cycle1.wheel_front
    

    Expected output

    Getting parameter [systems.wheel_slip.trisphere_cycle1.wheel_front] for registry namespace [/world/wheel_slip]... Parameter type [ign_msgs.WheelSlipParameters]

    ---

    slip_compliance_lateral: 1 slip_compliance_longitudinal: 1

  • Set the systems.wheel_slip.trisphere_cycle1.wheel_front parameter to a different value:

    ign param -r /world/wheel_slip -s -n systems.wheel_slip.trisphere_cycle1.wheel_front -t ign_msgs.WheelSlipParameters -m "
      slip_compliance_lateral: 1
      slip_compliance_longitudinal: 2"
    

    Expected output

    Setting parameter [systems.wheel_slip.trisphere_cycle1.wheel_front] for world [wheel_slip]...

    Parameter successfully set!

  • Get the systems.wheel_slip.trisphere_cycle1.wheel_front parameter again, its value should have changed:

    ign param -r /world/wheel_slip -g -n systems.wheel_slip.trisphere_cycle1.wheel_front
    

    Expected output

    Getting parameter [systems.wheel_slip.trisphere_cycle1.wheel_front] for registry namespace [/world/wheel_slip]... Parameter type [ign_msgs.WheelSlipParameters]

    ---

    slip_compliance_lateral: 1 slip_compliance_longitudinal: 2

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