Package: rsplan
READMEOverviewUsageInstallationRunningFAQExhibitsReferencesOverviewThis package is a Reeds-Shepp library implementation with Python that is compatible with Python versions >= 3.9, including 3.11.Contains the following files:planner: Path planning code.pathfunction outputs the optimal Reeds-Shepp path with or without a runway.curves: Curve formulas for all of the curve types in the Reeds-Shepp paper.primitives: Three class architectures (Waypoint, Segment, and Path).Waypoint class (stores x, y, yaw of the waypoint and the curvature and length of the segment the waypoint is on as well as if the segment is a runway)Segment class (stores left/right/straight type, forward/backward direction, length, and turn radius of the segment)Path class (stores start and end points, turn radius, step size, and list of Segments. Also contains a cached waypoints function to get a list of Waypoints for the path)helpers: Helper functions for planner, primitives, and curves files.demo: Demo/visualization of paths.UsageInstallationYou can install this software using pip:$ pip3 install -U rsplanRunningSee demo.py for example usagepath(start_pose, end_pose, turn_radius, runway_length, step_size, length_tolerance (optional))return a Reeds-Shepp path from start_pose to end_pose with specified turning radius and step_size between points. The length_tolerance default is 2 meters but can be set to user preference — if paths’ total lengths are within length tolerance of each other, the path function will choose the one with fewer segments as the optimal path. The runway_length is for the runway at the end of the path that helps improve accuracy in reaching the final position — this can be set to 0, or a positive or negative number for a forwards or backwards driving runway.start_pose and end_pose are in the formatTuple[float, float, float]of x, y, yaw values.FAQWhat are t, u, and v parameters?As a whole, t, u, v are segment parameters generated in each of the curve helper functions that represent the distance (angular distance for curved segments, linear distance for straight segments) of their respective segments.If there are 3 segments (ccc or csc), t is for segment 1, u is for segment 2, and v is for segment 3.If there are 4 or 5 segments, the format is:t, u, u, v for cccc paths (2nd and 3rd segments have same angular distance)t, pi/2, u, v for ccsc paths (2nd segment has angle pi/2)t, u, pi/2, v for cscc paths (3rd segment has angle pi/2)t, pi/2, u, pi/2, v for ccscc paths (2nd and 4th segments have angle pi/2)These are represented generally in the Segment class in the "distance" parameter, which we pass in t, u, v, or pi/2 for depending on the segment.ExhibitsHow to run the demoClone this repositoryUpdate_END_POSESpath coordinates in demo.py to the paths you would like to visualizeIn terminal in the rsplan subfolder of this rsplan repository, run:$ python3 demo.pyExample paths visualized from demo.py:Paths start from originFormat: (end x, end y, yaw, turn radius, runway length)(5, 6, np.pi, 1, 0)(15, 3, np.pi / 2.0, 2, 6)(-2, -4, np.pi, 4, 3)(-7, 2, np.pi, 4, 0)(-7, -7, 0.0, 6, 1)(0.7, 1.8, 1, 1, 1)(-5, 6, np.pi / 3.0, 2, 1)(7, 2, 0.0, 6, 3)(-4, -1, -np.pi / 2.0, 1, 3)ReferencesPaper providing more information on the algorithm:
Reeds, J., & Shepp, L. (1990). Optimal paths for a car that goes both forwards and backwards.https://msp.org/pjm/1990/145-2/pjm-v145-n2-p06-s.pdfCurve formulas can be found on page 390-391.
Inspiration for this Python implementation of the Reeds-Shepp algorithm:https://github.com/boyali/reeds_and_shepp_curves/tree/master