Add holonomic follower examples (#2052)

wpilibcExamples/src/main/cpp/examples/SwerveControllerCommand/include/subsystems/SwerveModule.h

@@ -0,0 +1,65 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2019 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#pragma once
+
+#include <frc/Encoder.h>
+#include <frc/Spark.h>
+#include <frc/controller/PIDController.h>
+#include <frc/controller/ProfiledPIDController.h>
+#include <frc/geometry/Rotation2d.h>
+#include <frc/kinematics/SwerveModuleState.h>
+#include <frc/trajectory/TrapezoidProfile.h>
+#include <wpi/math>
+
+#include "Constants.h"
+
+class SwerveModule {
+  using radians_per_second_squared_t =
+      units::compound_unit<units::radians,
+                           units::inverse<units::squared<units::second>>>;
+
+ public:
+  SwerveModule(int driveMotorChannel, int turningMotorChannel,
+               const int driveEncoderPorts[2], const int turningEncoderPorts[2],
+               bool driveEncoderReversed, bool turningEncoderReversed);
+
+  frc::SwerveModuleState GetState();
+
+  void SetDesiredState(frc::SwerveModuleState& state);
+
+  void ResetEncoders();
+
+ private:
+  // We have to use meters here instead of radians due to the fact that
+  // ProfiledPIDController's constraints only take in meters per second and
+  // meters per second squared.
+
+  static constexpr units::radians_per_second_t kModuleMaxAngularVelocity =
+      units::radians_per_second_t(wpi::math::pi);  // radians per second
+  static constexpr units::unit_t<radians_per_second_squared_t>
+      kModuleMaxAngularAcceleration =
+          units::unit_t<radians_per_second_squared_t>(
+              wpi::math::pi * 2.0);  // radians per second squared
+
+  frc::Spark m_driveMotor;
+  frc::Spark m_turningMotor;
+
+  frc::Encoder m_driveEncoder;
+  frc::Encoder m_turningEncoder;
+
+  bool m_reverseDriveEncoder;
+  bool m_reverseTurningEncoder;
+
+  frc2::PIDController m_drivePIDController{
+      ModuleConstants::kPModuleDriveController, 0, 0};
+  frc::ProfiledPIDController<units::radians> m_turningPIDController{
+      ModuleConstants::kPModuleTurningController,
+      0.0,
+      0.0,
+      {kModuleMaxAngularVelocity, kModuleMaxAngularAcceleration}};
+};