Safe Interval Path Planner

[SchwartzCode]

What does this implement/fix?

Implements the SafeInterval path planning algorithm as described in this paper

This script implements a safe-interval path planner for a 2d grid with dynamic obstacles. It is faster than
SpaceTime A* because it reduces the number of redundant node expansions by pre-computing regions of adjacent
time steps that are safe ("safe intervals") at each position. This allows the algorithm to skip expanding nodes
that are in intervals that have already been visited earlier.

Additional information

PR into the gifs repo:
AtsushiSakai/PythonRoboticsGifs#7

Gifs for reference:
250 obstacles:

Found path to goal after 764 expansions
Planning took: 0.59794 seconds

Hard-coded obstacle pattern:

Found path to goal after 322 expansions
Planning took: 0.00702 seconds

SpaceTime A* on this same arrangement:

Found path to goal after 2717154 expansions
Planning took: 20.30111 seconds

CheckList

• Did you add an unittest for your new example or defect fix?
• Did you add documents for your new example?
• All CIs are green? (You can check it after submitting)

[Copilot]

PR Overview

This PR implements a safe‑interval path planning algorithm for a 2D grid with dynamic obstacles, aimed at reducing redundant node expansions compared to SpaceTime A*.

• Implements a new SafeIntervalPathPlanner class along with supporting Node, NodePath, and interval utilities.
• Adds a dedicated test file to verify the planner’s functionality.
• Updates the GridWithDynamicObstacles module to provide safe interval computation and fixes a loop iteration issue.

Reviewed Changes

File	Description
PathPlanning/TimeBasedPathPlanning/SafeInterval.py	New implementation of the safe‑interval path planning algorithm using SIPP.
tests/test_safe_interval_path_planner.py	Added unittests verifying the correctness of the safe‑interval planner.
PathPlanning/TimeBasedPathPlanning/GridWithDynamicObstacles.py	Updates to safe intervals functions and a fix for iterating while modifying a list.

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

Comments suppressed due to low confidence (1)

PathPlanning/TimeBasedPathPlanning/SafeInterval.py:49

• For rich comparisons, lt (and similarly eq) should return NotImplemented instead of raising NotImplementedError. This will ensure proper behavior when comparing against other types.

if not isinstance(other, Node): return NotImplementedError(f"Cannot compare Node with object of type: {type(other)}")

[SchwartzCode]

Wow that copilot review is awesome!