Package trclib.archive

Class TrcHolonomicPurePursuitDrive

java.lang.Object
trclib.archive.TrcHolonomicPurePursuitDrive
public class TrcHolonomicPurePursuitDrive extends Object
This class implements a platform independent Pure Pursuit drive for holonomic robots. Essentially, a pure pursuit drive navigates the robot to chase a point along the path. The point to chase is chosen by intersecting a proximity circle centered on the robot with a specific radius with the path, and chasing the "furthest" intersection. The smaller the radius is, the more "tightly" the robot will follow a path, but it will be more prone to oscillation and sharp turns. A larger radius will tend to smooth out turns and corners. Note that the error tolerance must be less than the proximity radius, so choose them accordingly.

A path consists of an array of waypoints, specifying position, velocity, and optionally heading. All other properties of the TrcWaypoint object may be ignored.The path may be low resolution, as this automatically interpolates between waypoints. If you want the robot to maintain heading, call setMaintainHeading(true) and it will ignore all the heading values. Otherwise, call setMaintainHeading(false), ensure that the heading tolerance and pid coefficients are set, and it will follow the heading values specified by the path.

A somewhat similar idea is here: ... or ...

Note that this paper is for non-holonomic robots. This means that all the turning radius stuff isn't very relevant. Technically, we could impose limits on the turning radius as a function of robot velocity and max rot vel, but that's unnecessarily complicated, in my view. Additionally, it does point injection instead of interpolation, and path smoothing, which we don't do, since a nonzero proximity radius will naturally smooth it anyway.

  • Field Details

    • tracer

      private final TrcDbgTrace tracer

    • instanceName

      private final String instanceName

    • driveBase

      private final TrcDriveBase driveBase

    • driveTaskObj

      private final TrcTaskMgr.TaskObject driveTaskObj

    • posPidCtrl

      private final TrcPidController posPidCtrl

    • turnPidCtrl

      private final TrcPidController turnPidCtrl

    • velPidCtrl

      private final TrcPidController velPidCtrl

    • logRobotPoseEvents

      private boolean logRobotPoseEvents

    • tracePidInfo

      private boolean tracePidInfo

    • verbosePidInfo

      private boolean verbosePidInfo

    • battery

      private TrcRobotBattery battery

    • posTolerance

      private volatile double posTolerance

    • proximityRadius

      private volatile double proximityRadius

    • turnTolerance

      private volatile double turnTolerance

    • path

      private TrcPath path

    • pathIndex

      private int pathIndex

    • positionInput

      private double positionInput

    • onFinishedEvent

      private TrcEvent onFinishedEvent

    • timedOutTime

      private double timedOutTime

    • warpSpace

      private final TrcWarpSpace warpSpace

    • waypointEventHandler

      private TrcHolonomicPurePursuitDrive.WaypointEventHandler waypointEventHandler

    • interpolationType

      private TrcHolonomicPurePursuitDrive.InterpolationType interpolationType

    • maintainHeading

      private volatile boolean maintainHeading

    • startHeading

      private double startHeading

    • referencePose

      private TrcPose2D referencePose

    • moveOutputLimit

      private double moveOutputLimit

    • rotOutputLimit

      private double rotOutputLimit

  • Constructor Details

    • TrcHolonomicPurePursuitDrive

      public TrcHolonomicPurePursuitDrive(String instanceName, TrcDriveBase driveBase, double proximityRadius, double posTolerance, double turnTolerance, TrcPidController.PidCoefficients posPidCoeff, TrcPidController.PidCoefficients turnPidCoeff, TrcPidController.PidCoefficients velPidCoeff)
      Constructor: Create an instance of the object.
      Parameters:
      instanceName - specifies the instance name.
      driveBase - specifies the reference to the drive base.
      proximityRadius - specifies the distance between the robot and next following point.
      posTolerance - specifies the position tolerance.
      turnTolerance - specifies the turn tolerance.
      posPidCoeff - specifies the position PID coefficients.
      turnPidCoeff - specifies the turn PID coefficients.
      velPidCoeff - specifies the velocity PID coefficients.

    • TrcHolonomicPurePursuitDrive

      public TrcHolonomicPurePursuitDrive(String instanceName, TrcDriveBase driveBase, double proximityRadius, double posTolerance, TrcPidController.PidCoefficients posPidCoeff, TrcPidController.PidCoefficients turnPidCoeff, TrcPidController.PidCoefficients velPidCoeff)
      Constructor: Create an instance of the object.
      Parameters:
      instanceName - specifies the instance name.
      driveBase - specifies the reference to the drive base.
      proximityRadius - specifies the distance between the robot and next following point.
      posTolerance - specifies the position tolerance.
      posPidCoeff - specifies the position PID coefficients.
      turnPidCoeff - specifies the turn PID coefficients.
      velPidCoeff - specifies the velocity PID coefficients.

  • Method Details

    • toString

      public String toString()
      This method returns the instance name.
      Overrides:
      toString in class Object
      Returns:
      instance name.

    • setTraceLevel

      public void setTraceLevel(TrcDbgTrace.MsgLevel msgLevel, boolean logRobotPoseEvents, boolean tracePidInfo, boolean verbosePidInfo, TrcRobotBattery battery)
      This method sets the trace level for logging trace messages.
      Parameters:
      msgLevel - specifies the message level.
      logRobotPoseEvents - specifies true to log robot pose events, false otherwise.
      tracePidInfo - specifies true to enable tracing of PID info, false otherwise.
      verbosePidInfo - specifies true to trace verbose PID info, false otherwise.
      battery - specifies the battery object to get battery info for the message.

    • setTraceLevel

      public void setTraceLevel(TrcDbgTrace.MsgLevel msgLevel, boolean logRobotPoseEvents, boolean tracePidInfo, boolean verbosePidInfo)
      This method sets the trace level for logging trace messages.
      Parameters:
      msgLevel - specifies the message level.
      logRobotPoseEvents - specifies true to log robot pose events, false otherwise.
      tracePidInfo - specifies true to enable tracing of PID info, false otherwise.
      verbosePidInfo - specifies true to trace verbose PID info, false otherwise.

    • getTargetFieldPosition

      public TrcPose2D getTargetFieldPosition()
      This method returns the field position of the target waypoint of the path (i.e. the last waypoint in the path).
      Returns:
      field position of the last waypoint in the path.

    • setWaypointEventHandler

      public void setWaypointEventHandler(TrcHolonomicPurePursuitDrive.WaypointEventHandler handler)
      This method sets the waypoint event handler that gets called when the robot crosses each waypoint. This allows the caller to perform actions when each waypoint is reached. Waypoint handler is cleared when the start method is called. In other words, this method should only be called after the start method is called and the Waypoint event handler is only valid for the path started by the start method.
      Parameters:
      handler - specifies the waypoint event handler, can be null to clear the event handler.

    • setMaintainHeading

      public void setMaintainHeading(boolean maintainHeading)
      Maintain heading during path following, or follow the heading values in the path. If not maintaining heading, remember to set the heading tolerance!
      Parameters:
      maintainHeading - If true, maintain heading. If false, use closed loop to control heading.

    • setInterpolationType

      public void setInterpolationType(TrcHolonomicPurePursuitDrive.InterpolationType interpolationType)
      Configure the method of interpolating between waypoints. Methods ending with INV will favor the ending point.
      Parameters:
      interpolationType - The type of interpolation to use.

    • setPositionToleranceAndProximityRadius

      public void setPositionToleranceAndProximityRadius(double posTolerance, double proximityRadius)
      Set both the position tolerance and proximity radius.
      Parameters:
      posTolerance - sepcifies the distance at which the controller will stop itself.
      proximityRadius - specifies the distance between the robot and next following point.

    • setPositionTolerance

      public void setPositionTolerance(double posTolerance)
      Set the position tolerance to end the path. Units need to be consistent.
      Parameters:
      posTolerance - The distance at which the controller will stop itself.

    • setProximityRadius

      public void setProximityRadius(double proximityRadius)
      Set the following distance for the pure pursuit controller.
      Parameters:
      proximityRadius - specifies the distance between the robot and next following point.

    • setTurnTolerance

      public void setTurnTolerance(double turnTolerance)
      Set the turn tolerance to end the path. Units need to be consistent.
      Parameters:
      turnTolerance - The angle error at which the controller will stop itself.

    • setPositionPidCoefficients

      public void setPositionPidCoefficients(TrcPidController.PidCoefficients pidCoefficients)
      Sets the pid coefficients for the position controller. This will work in the middle of an operation as well.
      Parameters:
      pidCoefficients - The new PID coefficients for the position controller.

    • setTurnPidCoefficients

      public void setTurnPidCoefficients(TrcPidController.PidCoefficients pidCoefficients)
      Sets the pid coefficients for the turn controller. This will work in the middle of an operation as well.
      Parameters:
      pidCoefficients - The new PID coefficients for the heading controller.

    • setVelocityPidCoefficients

      public void setVelocityPidCoefficients(TrcPidController.PidCoefficients pidCoefficients)
      Sets the pid coefficients for the position controller. This will work in the middle of an operation as well. Note that velocity controllers should have an F term as well.
      Parameters:
      pidCoefficients - The new PIDF coefficients for the velocity controller.

    • setMoveOutputLimit

      public void setMoveOutputLimit(double limit)
      Sets the movement output power limit.
      Parameters:
      limit - specifies the output power limit for movement (X and Y).

    • setRotOutputLimit

      public void setRotOutputLimit(double limit)
      Sets the rotation output power limit.
      Parameters:
      limit - specifies the output power limit for rotation.

    • start

      public void start(TrcPath path, TrcEvent onFinishedEvent, double timeout, Double maxVel, Double maxAccel, Double maxDecel)
      Start following the supplied path using a pure pursuit controller. The velocity must always be positive, and the path must start at (0,0). Heading is absolute and position is relative in the starting robot reference frame.
      Parameters:
      path - The path to follow. Must start at (0,0).
      onFinishedEvent - When finished, signal this event.
      timeout - Number of seconds after which to cancel this operation. 0.0 for no timeout.
      maxVel - specifies the maximum velocity if applying trapezoid velocity profile, null if not.
      maxAccel - specifies the maximum acceleration if applying trapezoid velocity profile, null if not.
      maxDecel - specifies the maximum deceleration if applying trapezoid velocity profile, null if not.

    • start

      public void start(TrcPath path, TrcEvent onFinishedEvent, Double maxVel, Double maxAccel, Double maxDecel)
      Start following the supplied path using a pure pursuit controller. The velocity must always be positive, and the path must start at (0,0). Heading is absolute and position is relative in the starting robot reference frame.
      Parameters:
      path - The path to follow. Must start at (0,0).
      onFinishedEvent - When finished, signal this event.
      maxVel - specifies the maximum velocity if applying trapezoid velocity profile, null if not.
      maxAccel - specifies the maximum acceleration if applying trapezoid velocity profile, null if not.
      maxDecel - specifies the maximum deceleration if applying trapezoid velocity profile, null if not.

    • start

      public void start(TrcPath path, Double maxVel, Double maxAccel, Double maxDecel)
      Start following the supplied path using a pure pursuit controller. The velocity must always be positive, and the path must start at (0,0). Heading is absolute and position is relative in the starting robot reference frame.
      Parameters:
      path - The path to follow. Must start at (0,0).
      maxVel - specifies the maximum velocity if applying trapezoid velocity profile, null if not.
      maxAccel - specifies the maximum acceleration if applying trapezoid velocity profile, null if not.
      maxDecel - specifies the maximum deceleration if applying trapezoid velocity profile, null if not.

    • start

      public void start(TrcPath path, TrcEvent onFinishedEvent, double timeout)
      Start following the supplied path using a pure pursuit controller. The velocity must always be positive, and the path must start at (0,0). Heading is absolute and position is relative in the starting robot reference frame.
      Parameters:
      path - The path to follow. Must start at (0,0).
      onFinishedEvent - When finished, signal this event.
      timeout - Number of seconds after which to cancel this operation. 0.0 for no timeout.

    • start

      public void start(TrcPath path, TrcEvent onFinishedEvent)
      Start following the supplied path using a pure pursuit controller. The velocity must always be positive, and the path must start at (0,0). Heading is absolute and position is relative in the starting robot reference frame.
      Parameters:
      path - The path to follow. Must start at (0,0).
      onFinishedEvent - When finished, signal this event.

    • start

      public void start(TrcPath path)
      Start following the supplied path using a pure pursuit controller. The velocity must always be positive, and the path must start at (0,0). Heading is absolute and position is relative in the starting robot reference frame.
      Parameters:
      path - The path to follow. Must start at (0,0).

    • start

      public void start(TrcEvent onFinishedEvent, double timeout, boolean incrementalPath, Double maxVel, Double maxAccel, Double maxDecel, TrcPose2D... poses)
      This method starts the Pure Pursuit drive with the specified poses in the drive path.
      Parameters:
      onFinishedEvent - When finished, signal this event.
      timeout - specifies the maximum time allowed for this operation, 0.0 for no timeout.
      incrementalPath - specifies true if appending point is relative to the previous point in the path, false if appending point is in the same reference frame as startingPose.
      maxVel - specifies the maximum velocity if applying trapezoid velocity profile, null if not.
      maxAccel - specifies the maximum acceleration if applying trapezoid velocity profile, null if not.
      maxDecel - specifies the maximum deceleration if applying trapezoid velocity profile, null if not.
      poses - specifies an array of waypoint poses in the drive path.

    • start

      public void start(TrcEvent onFinishedEvent, boolean incrementalPath, Double maxVel, Double maxAccel, Double maxDecel, TrcPose2D... poses)
      This method starts the Pure Pursuit drive with the specified poses in the drive path.
      Parameters:
      onFinishedEvent - When finished, signal this event.
      incrementalPath - specifies true if appending point is relative to the previous point in the path, false if appending point is in the same reference frame as startingPose.
      maxVel - specifies the maximum velocity if applying trapezoid velocity profile, null if not.
      maxAccel - specifies the maximum acceleration if applying trapezoid velocity profile, null if not.
      maxDecel - specifies the maximum deceleration if applying trapezoid velocity profile, null if not.
      poses - specifies an array of waypoint poses in the drive path.

    • start

      public void start(boolean incrementalPath, Double maxVel, Double maxAccel, Double maxDecel, TrcPose2D... poses)
      This method starts the Pure Pursuit drive with the specified poses in the drive path.
      Parameters:
      incrementalPath - specifies true if appending point is relative to the previous point in the path, false if appending point is in the same reference frame as startingPose.
      maxVel - specifies the maximum velocity if applying trapezoid velocity profile, null if not.
      maxAccel - specifies the maximum acceleration if applying trapezoid velocity profile, null if not.
      maxDecel - specifies the maximum deceleration if applying trapezoid velocity profile, null if not.
      poses - specifies an array of waypoint poses in the drive path.

    • start

      public void start(TrcEvent onFinishedEvent, double timeout, boolean incrementalPath, TrcPose2D... poses)
      This method starts the Pure Pursuit drive with the specified poses in the drive path.
      Parameters:
      onFinishedEvent - When finished, signal this event.
      timeout - specifies the maximum time allowed for this operation, 0.0 for no timeout.
      incrementalPath - specifies true if appending point is relative to the previous point in the path, false if appending point is in the same reference frame as startingPose.
      poses - specifies an array of waypoint poses in the drive path.

    • start

      public void start(TrcEvent onFinishedEvent, boolean incrementalPath, TrcPose2D... poses)
      This method starts the Pure Pursuit drive with the specified poses in the drive path.
      Parameters:
      onFinishedEvent - When finished, signal this event.
      incrementalPath - specifies true if appending point is relative to the previous point in the path, false if appending point is in the same reference frame as startingPose.
      poses - specifies an array of waypoint poses in the drive path.

    • start

      public void start(boolean incrementalPath, TrcPose2D... poses)
      This method starts the Pure Pursuit drive with the specified poses in the drive path.
      Parameters:
      incrementalPath - specifies true if appending point is relative to the previous point in the path, false if appending point is in the same reference frame as startingPose.
      poses - specifies an array of waypoint poses in the drive path.

    • isActive

      public boolean isActive()
      Checks if the robot is currently following a path.
      Returns:
      True if the pure pursuit controller is active, false otherwise.

    • cancel

      public void cancel()
      If the controller is currently active, cancel the path following operation. Otherwise, do nothing. If there is an event to signal, mark it as cancelled.

    • getPositionInput

      private double getPositionInput()
      This method is called by the Position PID controller to get the current position of the robot. Since the position target is always zero, getPositionInput returns the negative distance of the robot from the next target point.
      Returns:
      negative distance of the robot from the next target point.

    • getVelocityInput

      private double getVelocityInput()
      This method is called by the Velocity PID controller to get the polar magnitude of the robot's velocity.
      Returns:
      robot's velocity magnitude.

    • stop

      private void stop()
      Stops PurePursuit drive.

    • driveTask

      private void driveTask(TrcTaskMgr.TaskType taskType, TrcRobot.RunMode runMode, boolean slowPeriodicLoop)
      This task is called periodically to calculate the next target point on the path. The next target point on the path has a distance of followDistance from the current robot position intersecting with the path segment towards the end of the endpoint of the path segment.
      Parameters:
      taskType - specifies the type of task being run.
      runMode - specifies the competition mode that is about to end (e.g. Autonomous, TeleOp, Test).
      slowPeriodicLoop - specifies true if it is running the slow periodic loop on the main robot thread, false otherwise.

    • interpolate

      private TrcWaypoint interpolate(TrcWaypoint point1, TrcWaypoint point2, double weight)
      Interpolates a waypoint that's weighted between two given waypoints.
      Parameters:
      point1 - specifies the start point of the path segment.
      point2 - specifies the end point of the path segment.
      weight - specifies the weight between the two provided points.
      Returns:
      weighted interpolated waypoint.

    • interpolate

      private double interpolate(double start, double end, double weight)
      Returns a weighted value between given values.
      Parameters:
      start - specifies the start value.
      end - specifies the end value.
      weight - specifies the weight between the values.
      Returns:
      weighted value between the given values.

    • getFollowingPointOnSegment

      private TrcWaypoint getFollowingPointOnSegment(TrcWaypoint prev, TrcWaypoint point, TrcPose2D robotPose)
      This method calculates the waypoint on the path segment that intersects the robot's proximity circle that is closest to the end point of the path segment. The algorithm is based on this article: ...
      Parameters:
      prev - specifies the start point of the path segment.
      point - specifies the end point of the path segment.
      robotPose - specifies the robot's position.
      Returns:
      calculated waypoint.

    • getFollowingPoint

      private TrcWaypoint getFollowingPoint(TrcPose2D robotPose)
      Determines the next target point for Pure Pursuit Drive to follow.
      Parameters:
      robotPose - specifies the robot's location.
      Returns:
      next target point for the robot to follow.