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Only released in EOL distros:   kinetic

Dependencies

This package depends on the following message definitions:

• cpswarm_msgs

The following library packages of the swarm behaviors library are required:

• swarm_behaviors_position

The following packages of the swarm functions library are required:

• target_monitor (only if single_target=true)

The following packages of the sensing and actuation library are required:

• area_provider
• obstacle_detection

Further required packages are:

• actionlib

• random_numbers

Execution

Run the launch file

roslaunch ugv_random_walk ugv_random_walk.launch

to launch the ugv_random_walk node.

The launch file can be configured with following parameters:

id (integer, default: 1)

• The identifier (ID) of the CPS used for name spacing in simulation.

output (string, default: screen)

• Whether to show the program output (screen) or to write it to a log file (log).

In the param subdirectory there is the parameter file ugv_random_walk.yaml that allows to configure the behavior of the ugv_random_walk node.

Nodes

ugv_random_walk

The ugv_random_walk performs coverage using the random walk algorithm. The random walk is a mathematical movement model, where an agent moves straight for a specific distance. Then, it changes its direction randomly into a direction that is clear of obstacles and moves straight again. If it arrives at the environment boundary, it reflects to continue its walk. When the parameter single_target is set to true, the UGV succeeds once a target has been found and returns the target ID and position.

Action Goal

ugv_coverage/goal (cpswarm_msgs/CoverageGoal)

• A goal that starts the random direction coverage behavior.

Action Result

ugv_coverage/result (cpswarm_msgs/CoverageResult)

• ID and position of the target that has been found.

Subscribed Topics

target_found (cpswarm_msgs/TargetPositionEvent)

• Position and ID of a target detected by the target monitor. Only subscribed when single_target is set to true.

Services Called

obstacle_detection/get_clear_sector (cpswarm_msgs/GetSector)

• Get the circular sector that is clear of obstacles.

area/closest_bound (cpswarm_msgs/ClosestBound)

• Get the coordinates of the closest boundary in order to reflect from it.

Parameters

~loop_rate (real, default: 5)

• The frequency in Hz at which to run the control loops.

~queue_size (integer, default: 1)

• The size of the message queue used for publishing and subscribing to topics.

~single_target (boolean, default: true)

• Whether the algorithm will succeed / terminate once a target has been found.

~step_size_max (real, default: 3.0)

• The distance in meter that a UGV travels in one step.

/rng_seed (integer, default: 0)

• The seed used for random number generation. In the default case, a random seed is generated.

Acknowledgements

This work is supported by the European Commission through the CPSwarm H2020 project under grant no. 731946.