ElevatorSim.h

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// Copyright (c) FIRST and other WPILib contributors.
// Open Source Software; you can modify and/or share it under the terms of
// the WPILib BSD license file in the root directory of this project.
 
#pragma once
 
#include <array>
 
#include <units/length.h>
#include <units/mass.h>
#include <units/velocity.h>
 
#include "frc/simulation/LinearSystemSim.h"
#include "frc/system/plant/DCMotor.h"
 
namespace frc::sim {
/**
 * Represents a simulated elevator mechanism.
 */
class ElevatorSim : public LinearSystemSim<2, 1, 2> {
 public:
  template <typename Distance>
  using Velocity_t = units::unit_t<
      units::compound_unit<Distance, units::inverse<units::seconds>>>;
 
  template <typename Distance>
  using Acceleration_t = units::unit_t<units::compound_unit<
      units::compound_unit<Distance, units::inverse<units::seconds>>,
      units::inverse<units::seconds>>>;
 
  /**
   * Constructs a simulated elevator mechanism.
   *
   * @param plant              The linear system that represents the elevator.
   *                           This system can be created with
   *                           LinearSystemId::ElevatorSystem().
   * @param gearbox            The type of and number of motors in your
   *                           elevator gearbox.
   * @param minHeight          The minimum allowed height of the elevator.
   * @param maxHeight          The maximum allowed height of the elevator.
   * @param simulateGravity    Whether gravity should be simulated or not.
   * @param startingHeight     The starting height of the elevator.
   * @param measurementStdDevs The standard deviation of the measurements.
   */
  ElevatorSim(const LinearSystem<2, 1, 2>& plant, const DCMotor& gearbox,
              units::meter_t minHeight, units::meter_t maxHeight,
              bool simulateGravity, units::meter_t startingHeight,
              const std::array<double, 2>& measurementStdDevs = {0.0, 0.0});
 
  /**
   * Constructs a simulated elevator mechanism.
   *
   * @param gearbox            The type of and number of motors in your
   *                           elevator gearbox.
   * @param gearing            The gearing of the elevator (numbers greater
   *                           than 1 represent reductions).
   * @param carriageMass       The mass of the elevator carriage.
   * @param drumRadius         The radius of the drum that your cable is
   *                           wrapped around.
   * @param minHeight          The minimum allowed height of the elevator.
   * @param maxHeight          The maximum allowed height of the elevator.
   * @param simulateGravity    Whether gravity should be simulated or not.
   * @param startingHeight     The starting height of the elevator.
   * @param measurementStdDevs The standard deviation of the measurements.
   */
  ElevatorSim(const DCMotor& gearbox, double gearing,
              units::kilogram_t carriageMass, units::meter_t drumRadius,
              units::meter_t minHeight, units::meter_t maxHeight,
              bool simulateGravity, units::meter_t startingHeight,
              const std::array<double, 2>& measurementStdDevs = {0.0, 0.0});
 
  /**
   * Constructs a simulated elevator mechanism.
   *
   * @param kV                 The velocity gain.
   * @param kA                 The acceleration gain.
   * @param gearbox            The type of and number of motors in your
   *                           elevator gearbox.
   * @param minHeight          The minimum allowed height of the elevator.
   * @param maxHeight          The maximum allowed height of the elevator.
   * @param simulateGravity    Whether gravity should be simulated or not.
   * @param startingHeight     The starting height of the elevator.
   * @param measurementStdDevs The standard deviation of the measurements.
   */
  template <typename Distance>
    requires std::same_as<units::meter, Distance> ||
             std::same_as<units::radian, Distance>
  ElevatorSim(decltype(1_V / Velocity_t<Distance>(1)) kV,
              decltype(1_V / Acceleration_t<Distance>(1)) kA,
              const DCMotor& gearbox, units::meter_t minHeight,
              units::meter_t maxHeight, bool simulateGravity,
              units::meter_t startingHeight,
              const std::array<double, 2>& measurementStdDevs = {0.0, 0.0});
  using LinearSystemSim::SetState;
 
  /**
   * Sets the elevator's state. The new position will be limited between the
   * minimum and maximum allowed heights.
   * @param position The new position
   * @param velocity The new velocity
   */
  void SetState(units::meter_t position, units::meters_per_second_t velocity);
 
  /**
   * Returns whether the elevator would hit the lower limit.
   *
   * @param elevatorHeight The elevator height.
   * @return Whether the elevator would hit the lower limit.
   */
  bool WouldHitLowerLimit(units::meter_t elevatorHeight) const;
 
  /**
   * Returns whether the elevator would hit the upper limit.
   *
   * @param elevatorHeight The elevator height.
   * @return Whether the elevator would hit the upper limit.
   */
  bool WouldHitUpperLimit(units::meter_t elevatorHeight) const;
 
  /**
   * Returns whether the elevator has hit the lower limit.
   *
   * @return Whether the elevator has hit the lower limit.
   */
  bool HasHitLowerLimit() const;
 
  /**
   * Returns whether the elevator has hit the upper limit.
   *
   * @return Whether the elevator has hit the upper limit.
   */
  bool HasHitUpperLimit() const;
 
  /**
   * Returns the position of the elevator.
   *
   * @return The position of the elevator.
   */
  units::meter_t GetPosition() const;
 
  /**
   * Returns the velocity of the elevator.
   *
   * @return The velocity of the elevator.
   */
  units::meters_per_second_t GetVelocity() const;
 
  /**
   * Returns the elevator current draw.
   *
   * @return The elevator current draw.
   */
  units::ampere_t GetCurrentDraw() const;
 
  /**
   * Sets the input voltage for the elevator.
   *
   * @param voltage The input voltage.
   */
  void SetInputVoltage(units::volt_t voltage);
 
 protected:
  /**
   * Updates the state estimate of the elevator.
   *
   * @param currentXhat The current state estimate.
   * @param u           The system inputs (voltage).
   * @param dt          The time difference between controller updates.
   */
  Vectord<2> UpdateX(const Vectord<2>& currentXhat, const Vectord<1>& u,
                     units::second_t dt) override;
 
 private:
  DCMotor m_gearbox;
  units::meter_t m_minHeight;
  units::meter_t m_maxHeight;
  bool m_simulateGravity;
};
}  // namespace frc::sim