Package edu.wpi.first.math.filter

Class SlewRateLimiter

java.lang.Object
edu.wpi.first.math.filter.SlewRateLimiter
public class SlewRateLimiter extends Object
A class that limits the rate of change of an input value. Useful for implementing voltage, setpoint, and/or output ramps. A slew-rate limit is most appropriate when the quantity being controlled is a velocity or a voltage; when controlling a position, consider using a TrapezoidProfile instead.

  • Constructor Summary

    Constructors
    Constructor
    Description
    SlewRateLimiter(double rateLimit)
    Creates a new SlewRateLimiter with the given positive rate limit and negative rate limit of -rateLimit.
    SlewRateLimiter(double positiveRateLimit, double negativeRateLimit, double initialValue)
    Creates a new SlewRateLimiter with the given positive and negative rate limits and initial value.

  • Method Summary

    Modifier and Type
    Method
    Description
    double
    calculate(double input)
    Filters the input to limit its slew rate.
    double
    lastValue()
    Returns the value last calculated by the SlewRateLimiter.
    void
    reset(double value)
    Resets the slew rate limiter to the specified value; ignores the rate limit when doing so.
    void
    setLimit(double rateLimit)
    Sets the rate-of-change limit to the given positive rate limit and negative rate limit of -rateLimit.
    void
    setLimit(double positiveRateLimit, double negativeRateLimit)
    Sets the rate-of-change limit to the given positive and negative rate limits.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • SlewRateLimiter

      public SlewRateLimiter(double positiveRateLimit, double negativeRateLimit, double initialValue)
      Creates a new SlewRateLimiter with the given positive and negative rate limits and initial value.
      Parameters:
      positiveRateLimit - The rate-of-change limit in the positive direction, in units per second. This is expected to be positive.
      negativeRateLimit - The rate-of-change limit in the negative direction, in units per second. This is expected to be negative.
      initialValue - The initial value of the input.

    • SlewRateLimiter

      public SlewRateLimiter(double rateLimit)
      Creates a new SlewRateLimiter with the given positive rate limit and negative rate limit of -rateLimit.
      Parameters:
      rateLimit - The rate-of-change limit, in units per second.

  • Method Details

    • calculate

      public double calculate(double input)
      Filters the input to limit its slew rate.
      Parameters:
      input - The input value whose slew rate is to be limited.
      Returns:
      The filtered value, which will not change faster than the slew rate.

    • lastValue

      public double lastValue()
      Returns the value last calculated by the SlewRateLimiter.
      Returns:
      The last value.

    • reset

      public void reset(double value)
      Resets the slew rate limiter to the specified value; ignores the rate limit when doing so.
      Parameters:
      value - The value to reset to.

    • setLimit

      public void setLimit(double positiveRateLimit, double negativeRateLimit)
      Sets the rate-of-change limit to the given positive and negative rate limits.
      Parameters:
      positiveRateLimit - The rate-of-change limit in the positive direction, in units per second. This is expected to be positive.
      negativeRateLimit - The rate-of-change limit in the negative direction, in units per second. This is expected to be negative.

    • setLimit

      public void setLimit(double rateLimit)
      Sets the rate-of-change limit to the given positive rate limit and negative rate limit of -rateLimit.
      Parameters:
      rateLimit - The rate-of-change limit in both directions, in units per second. This is expected to be positive.