Package edu.wpi.first.math.trajectory

Class TrapezoidProfile

java.lang.Object
edu.wpi.first.math.trajectory.TrapezoidProfile
public class TrapezoidProfile
extends Object
A trapezoid-shaped velocity profile.

While this class can be used for a profiled movement from start to finish, the intended usage is to filter a reference's dynamics based on trapezoidal velocity constraints. To compute the reference obeying this constraint, do the following.

Initialization: 


 TrapezoidProfile.Constraints constraints =
   new TrapezoidProfile.Constraints(kMaxV, kMaxA);
 TrapezoidProfile.State previousProfiledReference =
   new TrapezoidProfile.State(initialReference, 0.0);
 TrapezoidProfile profile = new TrapezoidProfile(constraints);

Run on update: 


 previousProfiledReference =
 profile.calculate(timeSincePreviousUpdate, previousProfiledReference, unprofiledReference);

where `unprofiledReference` is free to change between calls. Note that when the unprofiled reference is within the constraints, `calculate()` returns the unprofiled reference unchanged.

Otherwise, a timer can be started to provide monotonic values for `calculate()` and to determine when the profile has completed via `isFinished()`.

  • Constructor Details

  • Method Details

    • calculate

      @Deprecated(since="2024", forRemoval=true) public TrapezoidProfile.State calculate​(double t)
      Deprecated, for removal: This API element is subject to removal in a future version.
      Pass the desired and current state into calculate instead of constructing a new TrapezoidProfile with the desired and current state
      Calculates the position and velocity for the profile at a time t where the current state is at time t = 0.
      Parameters:
      t - How long to advance from the current state toward the desired state.
      Returns:
      The position and velocity of the profile at time t.

    • calculate

      public TrapezoidProfile.State calculate​(double t, TrapezoidProfile.State current, TrapezoidProfile.State goal)
      Calculates the position and velocity for the profile at a time t where the current state is at time t = 0.
      Parameters:
      t - How long to advance from the current state toward the desired state.
      current - The current state.
      goal - The desired state when the profile is complete.
      Returns:
      The position and velocity of the profile at time t.

    • timeLeftUntil

      public double timeLeftUntil​(double target)
      Returns the time left until a target distance in the profile is reached.
      Parameters:
      target - The target distance.
      Returns:
      The time left until a target distance in the profile is reached.

    • totalTime

      public double totalTime()
      Returns the total time the profile takes to reach the goal.
      Returns:
      The total time the profile takes to reach the goal.

    • isFinished

      public boolean isFinished​(double t)
      Returns true if the profile has reached the goal.

      The profile has reached the goal if the time since the profile started has exceeded the profile's total time.

      Parameters:
      t - The time since the beginning of the profile.
      Returns:
      True if the profile has reached the goal.