path msgs

Description

This package bundles all message definitions of the navigation packages and has no further functionality.

Messages

Goal

Goal.msg represents the specification of a goal condition for the path planner.

There are currently two ways to specify a goal:

1. In POSE mode, the field pose represents a pose in the world where the robot should move to. The search terminates once a pose that is close enough has been found. For more information, see PlannerOptions.msg.

2. In MAP mode, the pose field is ignored. Instead the map field is used to determine goal conditions. The search terminates once a pose is reached for which map contains a value larger than map_search_min_value. The search is prolonged until map_search_min_candidates goals have been found, of which the best is chosen.

Directional Path

path_msgs/DirectionalPath associates a direction to a path. It is the same as nav_msgs/Path with an added field called forward indicating the direction.

Path Sequence

path_msgs/PathSequence is an array of path_msgs/DirectionalPaths. A sequence of length 0 is used to represent that no path exists. Sequences can have arbitrary length, usually switching direction among neighboring entries.

Obstacle

path_msgs/Obstacles is used as feedback information. The message represents a single obstacle point on the current path.

Planner Options

path_msgs/PlannerOptions conveys parameters for the path search. Individual parameters include obstacle growth factors, termination criteria and directional constraints.

Follower Options

path_msgs/FollowerOptions conveys parameters for the path follower, most importantly the maximal velocity. The optional fields robot_controller, local_planner and collision_avoider can be used to use a specific robot controller, local planner or collision avoider respectively.

Actions

Communication between nodes is implemented in the ActionLib framework. The following acitons can be performed:

Plan Path

path_msgs/PlanPath instructs the path planner to find a path. The field goal of type path_msgs/Goal is used for goal specification and planner_options contains the search parameters. A start pose can optionally be specified, otherwise TF is used.

The resulting path_msgs/PathSequence is empty if no path is found and otherwise contains all sub paths necessary.

Follow Path

path_msgs/FollowPath instructs the path follower to follow a path. The field path contains the path to follow and follower_options contains parameters for the follower.

Navigate To Goal

path_msgs/NavigateToGoal combines path planning and following. The messages instructs the Path Control node to navigate the robot to a goal. The failure_mode field determines whether multiple planning and following phases should be used in the event of a following failure.