Parameters and Topics

Parameters

Parameters used in the frontier-based exploration planner are located in uav_frontier_exploration_3d/config folder and defined in the .yaml files. Each scenario has its own .yaml file. The parameters are devided into three groups: exploration, octomap and clustering.

Exploration parameters

• global_frame: Name of the global frame (string)
• base_link_frame: Name of the robot frame (string)
• depth: The level at which clustering and best frontier selection is performed [1, 16]. A frontier detection level is fixed and set to 16 (int)
• radius: If the candidate point is inside the radius of the previous visited points, the candidate is deleted from the candidate list (double)
• bbx_minX: Minimum x-coordinate value of the scenario in the global_frame . This bounds the frontier detection and not the path planning (double)
• bbx_manX: Maximum x-coordinate value of the scenario in the global_frame . This bounds the frontier detection and not the path planning (double)
• bbx_minY: Minimum y-coordinate value of the scenario in the global_frame . This bounds the frontier detection and not the path planning (double)
• bbx_maxY: Maximum y-coordinate value of the scenario in the global_frame . This bounds the frontier detection and not the path planning (double)
• bbx_minZ: Minimum z-coordinate value of the scenario in the global_frame . This bounds the frontier detection and not the path planning (double)
• bbx_maxZ: Maximum z-coordinate value of the scenario in the global_frame . This bounds the frontier detection and not the path planning (double)
• box_lenght: Length of one side of the cube inside which we calculate information gain (double)
• k_gain: Constant, used to scale exponential function in the information gain (double)
• lambda: Constant, small lambda means that motion is cheap and gives priority to the information gain (double)
• volume: The total volume of the exploration environment, used for the /red/octomap_volume topic (double)

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OctoMap parameters

• resolution: The OctoMap resolution (double)
• octree_depth: Max exploration depth of the OctoMap, fixed and set to 16 (int)
• filename: File name for the OctoMap saving (string)
• file_path: File path for the OctoMap saving (string)

Clustering parameters

• kernel_bandwidth: A parameter inside mean-shift clustering algorithm, a higher bandwidth will result in fewer but larger clusters (double)

Topics

In order to successfully launch frontier-based exploration, you need to remap topics in the frontier_server.launch.

• cloud_in: Input point cloud from LiDAR/camera (sensor_msgs/PointCloud2)
• odometry: Current UAV odometry (nav_msgs/Odometry)
• carrot_pose: Current UAV reference (geometry_msgs/PoseStamped)
• point_reached: Published when the UAV reaches a target point (std_msgs/Bool)
• octomap_volume: Occupied, free, total and unmapped volumes for data analysis (std\msgs/Float64MultiArray)

Services

• exploration/toggle: Start exploration (std_srvs/SetBool)
• exploration/save_octomap: Save OctoMap with a desire filename at the desire location (file_path) (std_srvs/Empty)