Cpp Example: Build an Auto

In PathPlannerLib, autos are created using the PathPlannerAuto class. This class is essentially just a command group that will build itself based on an auto file created in the GUI. Therefore, you can use PathPlannerAuto just like any other command, i.e add to a SendableChooser, bind to a button, etc.

Before creating an auto, you must first configure the AutoBuilder, so that the auto is able to build itself with the correct path following command and settings.

Configuring AutoBuilder

There are a few options for configuring AutoBuilder, one for each type of path following command: Holonomic, Ramsete, and LTV. Since all of the AutoBuilder configuration is related to the drive subsystem, it is recommended to configure AutoBuilder at the end of your drive subsystem's constructor. NOTE: You can only configure AutoBuilder once. An exception will be thrown if you try to configure it multiple times.

Holonomic

#include <pathplanner/lib/auto/AutoBuilder.h>
#include <pathplanner/lib/util/HolonomicPathFollowerConfig.h>
#include <pathplanner/lib/util/PIDConstants.h>
#include <pathplanner/lib/util/ReplanningConfig.h>
#include <frc/geometry/Pose2d.h>
#include <frc/kinematics/ChassisSpeeds.h>

using namespace pathplanner;

SwerveSubsystem::SwerveSubsystem(){
    // Do all subsystem initialization here
    // ...

    // Configure the AutoBuilder last
    AutoBuilder::configureHolonomic(
        [this](){ return getPose(); }, // Robot pose supplier
        [this](frc::Pose2d pose){ resetPose(pose); }, // Method to reset odometry (will be called if your auto has a starting pose)
        [this](){ return getRobotRelativeSpeeds(); }, // ChassisSpeeds supplier. MUST BE ROBOT RELATIVE
        [this](frc::ChassisSpeeds speeds){ driveRobotRelative(speeds); }, // Method that will drive the robot given ROBOT RELATIVE ChassisSpeeds
        HolonomicPathFollowerConfig( // HolonomicPathFollowerConfig, this should likely live in your Constants class
            PIDConstants(5.0, 0.0, 0.0), // Translation PID constants
            PIDConstants(5.0, 0.0, 0.0), // Rotation PID constants
            4.5_mps, // Max module speed, in m/s
            0.4_m, // Drive base radius in meters. Distance from robot center to furthest module.
            ReplanningConfig() // Default path replanning config. See the API for the options here
        ),
        this // Reference to this subsystem to set requirements
    );
}

Ramsete

This example will use the default Ramsete configuration. If you would like to customize the b and zeta terms, there is another AutoBuilder configuration method with that option.

#include <pathplanner/lib/auto/AutoBuilder.h>
#include <pathplanner/lib/util/ReplanningConfig.h>
#include <frc/geometry/Pose2d.h>
#include <frc/kinematics/ChassisSpeeds.h>

using namespace pathplanner;

DriveSubsystem::DriveSubsystem(){
    // Do all subsystem initialization here
    // ...

    // Configure the AutoBuilder last
    AutoBuilder::configureRamsete(
        [this](){ return getPose(); }, // Robot pose supplier
        [this](frc::Pose2d pose){ resetPose(pose); }, // Method to reset odometry (will be called if your auto has a starting pose)
        [this](){ return getRobotRelativeSpeeds(); }, // ChassisSpeeds supplier. MUST BE ROBOT RELATIVE
        [this](frc::ChassisSpeeds speeds){ driveRobotRelative(speeds); }, // Method that will drive the robot given ROBOT RELATIVE ChassisSpeeds
        ReplanningConfig(), // Default path replanning config. See the API for the options here
        this // Reference to this subsystem to set requirements
    );
}

LTV

This example will use the default LTV configuration. If you would like to customize the qelems and relems terms, there is another AutoBuilder configuration method with that option.

#include <pathplanner/lib/auto/AutoBuilder.h>
#include <pathplanner/lib/util/ReplanningConfig.h>
#include <frc/geometry/Pose2d.h>
#include <frc/kinematics/ChassisSpeeds.h>

using namespace pathplanner;

DriveSubsystem::DriveSubsystem(){
    // Do all subsystem initialization here
    // ...

    // Configure the AutoBuilder last
    AutoBuilder::configureLTV(
        [this](){ return getPose(); }, // Robot pose supplier
        [this](frc::Pose2d pose){ resetPose(pose); }, // Method to reset odometry (will be called if your auto has a starting pose)
        [this](){ return getRobotRelativeSpeeds(); }, // ChassisSpeeds supplier. MUST BE ROBOT RELATIVE
        [this](frc::ChassisSpeeds speeds){ driveRobotRelative(speeds); }, // Method that will drive the robot given ROBOT RELATIVE ChassisSpeeds
        0.02_s, // Robot control loop period in seconds. Default is 0.02
        ReplanningConfig(), // Default path replanning config. See the API for the options here
        this // Reference to this subsystem to set requirements
    );
}

Create an Auto

After you have configured the AutoBuilder, creating an auto is as simple as constructing a PathPlannerAuto with the name of the auto you made in the GUI.

#include <pathplanner/lib/commands/PathPlannerAuto.h>

using namespace pathplanner;

frc2::CommandPtr RobotContainer::getAutonomousCommand(){
    return PathPlannerAuto("Example Auto").ToPtr();
}