TrapezoidProfile

class wpimath.trajectory.TrapezoidProfile(constraints: wpimath._controls._controls.trajectory.TrapezoidProfile.Constraints)

Bases: pybind11_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:

constraints = TrapezoidProfile.Constraints(kMaxV, kMaxA)
previousProfiledReference = initialReference

Run on update:

profile = TrapezoidProfile(constraints, unprofiledReference, previousProfiledReference)
previousProfiledReference = profile.calculate(timeSincePreviousUpdate)

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().

Constructs a TrapezoidProfile.

Parameters:

constraints – The constraints on the profile, like maximum velocity.

class Constraints(maxVelocity: wpimath.units.units_per_second, maxAcceleration: wpimath.units.units_per_second_squared)

Bases: pybind11_object

Profile constraints.

Constructs constraints for a Trapezoid Profile.

Parameters:

  • maxVelocity – Maximum velocity.

  • maxAcceleration – Maximum acceleration.

property maxAcceleration → wpimath.units.units_per_second_squared

Maximum acceleration.

property maxVelocity → wpimath.units.units_per_second

Maximum velocity.

class State(position: float = 0, velocity: wpimath.units.units_per_second = 0)

Bases: pybind11_object

Profile state.

property position → float

The position at this state.

property velocity → wpimath.units.units_per_second

The velocity at this state.

calculate(t: wpimath.units.seconds, current: wpimath._controls._controls.trajectory.TrapezoidProfile.State, goal: wpimath._controls._controls.trajectory.TrapezoidProfile.State) → wpimath._controls._controls.trajectory.TrapezoidProfile.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.

  • current – The current state.

  • goal – The desired state when the profile is complete.

Returns:

The position and velocity of the profile at time t.

isFinished(t: wpimath.units.seconds) → bool

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.

timeLeftUntil(target: float) → wpimath.units.seconds

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() → wpimath.units.seconds

Returns the total time the profile takes to reach the goal.

Returns:

The total time the profile takes to reach the goal.