PathPlanner

PathPlanner is a library used to transform a series of waypoints that make up a path into a trajectory that the robot can automatically follow during an autonomous routine or macro.

Most trajectories need to be defined in the PathPlannerTrajectoryGenerator (in PathPlannerTrajectoryGenerator.java under core_robot/src/main/java/frc/robot/driver) within the generateTrajectories(...) function and assigned a name.

Each trajectory is added to a trajectoryManager, which stores all generated paths. The pathPlanner.buildTrajectory() function manages generating the trajectory based on a set of constraints. Each path can have its own maximum acceleration and velocity for both translational movements (forward, backward, left, right) and rotational movements (spinning clockwise or counterclockwise). The path is then formed from a series of PathPlannerWaypoint and PathPlannerRotationTarget objects, which represent the desired locations or orientations through which the robot will pass. The PathPlannerWaypoint(...) takes the x-coordinate, y-coordinate, heading, and orientation. The heading is the direction that the robot will be traveling when moving to/through the waypoint, and the orientation is the direction the robot will face while traveling to/through the given waypoint.

After the path is described and built into a trajectory, the addTrajectory(...) function will take parameters for the name of the path and for whether it is specific to the red alliance (Optional.of(Alliance.Red)), blue alliance (Optional.of(Alliance.Blue)), or can be used for any alliance (Optional.empty()).

addTrajectory(
    trajectoryManager,
    pathPlanner.buildTrajectory(
        TuningConstants.MAX_TRANSLATIONAL_VELOCITY,
        TuningConstants.MAX_TRANSLATIONAL_ACCELERATION,
        TuningConstants.MAX_ROTATIONAL_VELOCITY,
        TuningConstants.MAX_ROTATIONAL_ACCELERATION,
        new PathPlannerWaypoint(200, 200, -180, 0),
        new PathPlannerWaypoint(100, 100, -180, 0)),
    "TheBestPathEverWritten",
    Optional.empty());