MecanumDriveKinematicsConstraint.h

Go to the documentation of this file.

// 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 <cmath>
 
#include <wpi/SymbolExports.h>
 
#include "frc/kinematics/MecanumDriveKinematics.h"
#include "frc/trajectory/constraint/TrajectoryConstraint.h"
#include "units/math.h"
#include "units/velocity.h"
 
namespace frc {
/**
 * A class that enforces constraints on the mecanum drive kinematics.
 * This can be used to ensure that the trajectory is constructed so that the
 * commanded velocities for wheels of the drivetrain stay below a certain
 * limit.
 */
class WPILIB_DLLEXPORT MecanumDriveKinematicsConstraint
    : public TrajectoryConstraint {
 public:
  MecanumDriveKinematicsConstraint(const MecanumDriveKinematics& kinematics,
                                   units::meters_per_second_t maxSpeed)
      : m_kinematics(kinematics), m_maxSpeed(maxSpeed) {}
 
  units::meters_per_second_t MaxVelocity(
      const Pose2d& pose, units::curvature_t curvature,
      units::meters_per_second_t velocity) const override {
    auto xVelocity = velocity * pose.Rotation().Cos();
    auto yVelocity = velocity * pose.Rotation().Sin();
    auto wheelSpeeds = m_kinematics.ToWheelSpeeds(
        {xVelocity, yVelocity, velocity * curvature});
    wheelSpeeds.Desaturate(m_maxSpeed);
 
    auto normSpeeds = m_kinematics.ToChassisSpeeds(wheelSpeeds);
 
    return units::math::hypot(normSpeeds.vx, normSpeeds.vy);
  }
 
  MinMax MinMaxAcceleration(const Pose2d& pose, units::curvature_t curvature,
                            units::meters_per_second_t speed) const override {
    return {};
  }
 
 private:
  MecanumDriveKinematics m_kinematics;
  units::meters_per_second_t m_maxSpeed;
};
}  // namespace frc