Laser Scan Obstacle Observer Package

Introduction

This package determines if the laserscan has any points that fall within the robot's footprint.

Explanation

This package subscribes to a laserscan topic (/scan) and uses the even-odd rule to determine if the laserscan data falls within the robot's footprint /move_base/global_costmap/footprint. The footprint can be inflated with the ~/padded_footprint param.

If the laserscan points are within the robot footprint, then the ~/is_obstructed topic would publish true. Else, it publishes false. See below for example.

The user might find the remap function useful to remap the topics to their desire.

This package was built for ROS Noetic on Ubuntu 20-04.

Usage

Before launching this node, please ensure that the robot is localised, and in particular, the tf from the map frame to the frame that /scan is published on is available. This is because the footprint published by /move_base/global_costmap/footprint is in map frame, and interally in this package, a transform is done for the footprint polygon into the frame /scan is in.

Start laser_scan_obstacle_observer_node that listens to /scan and /move_base/global_costmap/footprint with padded_footprint=0.1.

rosrun laser_scan_obstacle_observer laser_scan_obstacle_observer_node _padded_footprint:=0.1

Topics subscribed

1. /scan [sensor_msgs/LaserScan]: Laserscan to be transformed from.
2. /move_base/global_costmap/footprint [geometry_msgs/PolygonStamped]: Footprint of the robot.

Topics published

1. ~/is_obstructed [std_msgs/Bool]: Boolean whether there's a laserscan point in the robot's footprint.
2. ~/footprint [geometry_msgs/PolygonStamped]: Footprint that was used to determine if the laserscan is within the robot's footprint (i.e. padded footprint in /scan frame).