Continuous-CBS

Continuous CBS - a modification of conflict based search algorithm, that allows to perform actions of any arbitrary duration. The main differences are the representation of constraints, timeline, collision detection mechanism and using SIPP algorithm as a low-level planner. More info about CCBS and its principles of work you can find at https://arxiv.org/abs/1901.05506

Note that master branch contains a version of CCBS that uses grids as the description of environment. You can find a version that allows to use non regular graphs, such as roadmaps, at https://github.com/PathPlanning/Continuous-CBS/tree/CCBS-graphs

Getting Started

To go and try this algorithm you can use QtCreator or CMake. Both .pro and CMakeLists files are available in the repository.

Notice, that project uses C++11 standart. Make sure that your compiler supports it.

These instructions will get you a copy of the project up and running on your local machine for development and testing purposes.

Prerequisites

Qt Creator — a cross-platform C++, JavaScript and QML integrated development environment which is part of the SDK for the Qt GUI Application development framework.

CMake — an open-source, cross-platform family of tools designed to build, test and package software.

Installing

Download current repository to your local machine. Use

git clone https://github.com/PathPlanning/Continuous-CBS.git

or direct downloading.

Built current project using Qt Creator or CMake. To launch the compiled file you will need to pass input XML file as an argument. Output file for this project will be placed in the same folder as input file and, by default, will be named _log.xml. For examlpe, using CMake

cd PATH_TO_THE_PROJECT
cmake .
make

Input and Output files

The examples of input and output files you can find in the Examples folder.

Options

There are some options that can be controlled through the const.h file:

CN_K - controls the connectedness of the grid. Possible values: 2 - 4 cardinal neighbors; 3 - 4 cardinal + 4 diagonal; 4 - 16 neighbors; 5 - 32 neighbors.
CN_CARDINAL - controls whether the algorithm is looking for cardinal and semi-cardinal collisions or not. Possible values are 1(true) or 0 (false).
CN_HISTORY - controls whether the algorithm uses the information about previosly found collisions. This option allows to reduce the time requred for collision detection function, but it can't be directly combined with looking for cardinal conflicts. Possible values are 1(true) or 0 (false).
CN_STOP_CARDINAL - this option allows to stop looking for cardinal conflicts in cases, when the algorithm cannot find them anymore in the current branch of high-level tree. It also allows to combine CN_CARDINAL and CN_HISTORY options. Possible values are 1(true) or 0 (false).
CN_TIMELIMIT - controls the maximum runtime of the algorithm. Possible values are >0. For example CN_TIMELIMIT 60 means that the algorithm can spend up to 60 seconds to find a solution.
CN_AGENT_SIZE - controls the size (radii) of the agents' shape. Possible values are >0.
CN_DELTA - additional option, that controls the precision of detection of the end of collision interval (the moment of time when there is no more collision between the agents). The lower the value - the preciser the algorithm finds the end of collision interval, but it takes more time. Possible values are >0.

Launch

To launch the application you need to have map and taks input XML-files with all required information:

./C-CBS map.xml task.xml

The output file will be placed in the same folder as input files and, by default, will be named as task-file plus _log.xml. For examlpe,

"initial_task_file_name.xml" -> "initial_task_file_name_log.xml"