Path Planning

path_planning.py

Overview

path_planning.py is a skeleton global planner that emits a single dummy waypoint at 1 Hz. It lets downstream local planners, controllers and visualisers run before the real global planner is available.

Interfaces (strongly-typed, stateless)

Direction

Topic

Message type / Notes

Required

/{robot}/map

nav_msgs/OccupancyGrid – static or SLAM map

Required

/{robot}/odom_slam

nav_msgs/Odometry – robot pose in map frame

Provided

/{robot}/planned_path

nav_msgs/Path – single-PoseStamped at (1.0, 1.0), 1 Hz

Contract

Pre-conditions

  • Messages published on /map and /odom_slam share the same frame.

  • Both topics must have published at least once before planning.

Post-conditions

  • Every second, exactly one nav_msgs/Path is published.

  • Path header uses the map’s frame_id and current time stamp.

  • A single PoseStamped goal at coordinates (1.0, 1.0) is appended.

Invariants

  • Planner does not block; if data is missing it waits silently.

  • Orientation of the goal pose remains the default identity quaternion.

Implementation notes

  • Use rospy.Rate(1) to enforce 1 Hz.

  • queue_size=1 on the publisher to always keep the latest plan.

  • Replace plan_path() with a full search algorithm when ready.

class path_planning.PathPlanner[source]

Bases: object

Skeleton path planner that publishes a one-step plan each second.

Variables

map_msgnav_msgs.msg.OccupancyGrid | None

Latest map message.

odom_msgnav_msgs.msg.Odometry | None

Latest odometry message.

path_pubrospy.Publisher

Publisher for /planned_path.

  1. Read robot_id from CLI.

  2. Initialise ROS node <robot>_path_planning_node.

  3. Subscribe to /map and /odom_slam.

  4. Advertise /planned_path with queue_size=1.

loop() → None[source]

Run plan_path() at 1 Hz until ROS shuts down.

map_callback(msg: nav_msgs.msg.OccupancyGrid) → None[source]

Store the latest occupancy grid.

Parameters:

msg (nav_msgs.msg.OccupancyGrid) – Static or SLAM-produced map.

odom_callback(msg: nav_msgs.msg.Odometry) → None[source]

Store the latest odometry.

Parameters:

msg (nav_msgs.msg.Odometry) – Robot pose in the map frame.

plan_path() → None[source]

Publish a one-step Path when both map and odometry are available.

Preconditions

  • self.map_msg and self.odom_msg are not None.

Workflow

  1. Create a nav_msgs/Path, stamp it with rospy.Time.now() and set frame_id to self.map_msg.header.frame_id.

  2. Create a geometry_msgs/PoseStamped at (1.0, 1.0) in the map frame.

  3. Append the pose to path.poses.

  4. Publish on /planned_path and log at INFO level.