core / com.acmerobotics.roadrunner.followers / TrajectoryFollower

TrajectoryFollower

abstract class TrajectoryFollower

Generic Trajectory follower for time-based pose reference tracking.

Parameters

admissibleError - admissible/satisfactory pose error at the end of each move

timeout - max time to wait for the error to be admissible

clock - clock

Constructors

<init>

TrajectoryFollower(admissibleError: Pose2d = Pose2d(), timeout: Double = 0.0, clock: NanoClock = NanoClock.system())

Generic Trajectory follower for time-based pose reference tracking.

Properties

clock

val clock: NanoClock

clock

lastError

abstract var lastError: Pose2d

Robot pose error computed in the last update call.

trajectory

lateinit var trajectory: Trajectory

Trajectory being followed if isFollowing is true.

Functions

elapsedTime

fun elapsedTime(): Double

Returns the elapsed time since the last followTrajectory call.

followTrajectory

open fun followTrajectory(trajectory: Trajectory): Unit

Follow the given trajectory.

internalUpdate

abstract fun internalUpdate(currentPose: Pose2d): DriveSignal

isFollowing

fun isFollowing(): Boolean

Returns true if the current trajectory has finished executing.

update

fun update(currentPose: Pose2d): DriveSignal

Run a single iteration of the trajectory follower.

Inheritors

HolonomicPIDVAFollower

class HolonomicPIDVAFollower : TrajectoryFollower

Traditional PID controller with feedforward velocity and acceleration components to follow a trajectory. More specifically, the feedback is applied to the components of the robot's pose (x position, y position, and heading) to determine the velocity correction. The feedforward components are instead applied at the wheel level.

RamseteFollower

class RamseteFollower : TrajectoryFollower

Time-varying, non-linear feedback controller for nonholonomic drives. See equation 5.12 of Ramsete01.pdf.

TankPIDVAFollower

class TankPIDVAFollower : TrajectoryFollower

Traditional PID controller with feedforward velocity and acceleration components to follow a trajectory. More specifically, one feedback loop controls the path displacement (that is, x in the robot reference frame), and another feedback loop to minimize cross track (lateral) error via heading correction (overall, very similar to HolonomicPIDVAFollower except adjusted for the nonholonomic constraint). Feedforward is applied at the wheel level.