Obstacle layer dynamic parameters

[AadityaRavindran]

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Basic Info

Info	Please fill out this column
Ticket(s) this addresses	#956
Primary OS tested on	Ubuntu
Robotic platform tested on	gazebo turtlebot simulation

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Description of contribution in a few bullet points

Added dynamic parameter update from this list: https://github.com/ros-planning/navigation/blob/noetic-devel/costmap_2d/cfg/ObstaclePlugin.cfg (enabled, footprint_clearing_enabled, max_obstacle_height, and combination_method)

Description of documentation updates required from your changes

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Future work that may be required in bullet points

For Maintainers:

• Check that any new parameters added are updated in navigation.ros.org
• Check that any significant change is added to the migration guide
• Check that any new features OR changes to existing behaviors are reflected in the tuning guide
• Check that any new functions have Doxygen added
• Check that any new features have test coverage
• Check that any new plugins is added to the plugins page
• If BT Node, Additionally: add to BT's XML index of nodes for groot, BT package's readme table, and BT library lists

[mergify]

@AadityaPatanjali, please properly fill in PR template in the future. @SteveMacenski, use this instead.

• Check that any new parameters added are updated in navigation.ros.org
• Check that any significant change is added to the migration guide
• Check that any new features OR changes to existing behaviors are reflected in the tuning guide
• Check that any new functions have Doxygen added
• Check that any new features have test coverage
• Check that any new plugins is added to the plugins page
• If BT Node, Additionally: add to BT's XML index of nodes for groot, BT package's readme table, and BT library lists

[jwallace42]

LGTM I would wait for @SteveMacenski to take a look and for wait for checks to pass.

[SteveMacenski]

@indraneelpatil what are your thoughts on this? You approve? @AadityaPatanjali, @indraneelpatil did the initial one for Obstacle layer, but this looks good to me!

[doisyg]

Hum, what happens here if the update frequency of the layer is very small or equal to zero ? combination_method probably won't have an immediate effect after being set. Same for max_obstacle_height, enabled and footprint_clearing_enabled
I believe costs, footprint and bounds have to be updated in case a parameter impacting them has been changed

[SteveMacenski]

Why? It wouldn't take effect until the next time there's a costmap layer update anyway so why preemptively do it?

Enabled / footprint_clearing_enabled / combination_method are only used when there's an update coming. So changing it immediately or waiting for the next cycle would make no difference (e.g. it won't be used until then anywhere). Even Max Obstacle Height is only used in update bounds too https://github.com/ros-planning/navigation2/blob/da602f8a19fa6aaa7078e56ff0c3c83517feb533/nav2_costmap_2d/plugins/obstacle_layer.cpp#L452.

You would be correct about max_obstacle_height though if we were talking about the sensor's data stream max_obstacle_height since the observation buffer will do some work. However, only the global layer-level max_obstacle_height is reconfigurable. So far, none of the individual sensor stream parameterizations are dynamic here or in the voxel layer