[wpilib] Add HolonomicDriveController class and tests

wpilibc/src/main/native/include/frc/controller/HolonomicDriveController.h

@@ -0,0 +1,112 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2020 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 <units/angle.h>
+#include <units/velocity.h>
+
+#include "frc/controller/PIDController.h"
+#include "frc/controller/ProfiledPIDController.h"
+#include "frc/geometry/Pose2d.h"
+#include "frc/geometry/Rotation2d.h"
+#include "frc/kinematics/ChassisSpeeds.h"
+#include "frc/trajectory/Trajectory.h"
+
+namespace frc {
+/**
+ * This holonomic drive controller can be used to follow trajectories using a
+ * holonomic drive train (i.e. swerve or mecanum). Holonomic trajectory
+ * following is a much simpler problem to solve compared to skid-steer style
+ * drivetrains because it is possible to individually control forward, sideways,
+ * and angular velocity.
+ *
+ * The holonomic drive controller takes in one PID controller for each
+ * direction, forward and sideways, and one profiled PID controller for the
+ * angular direction. Because the heading dynamics are decoupled from
+ * translations, users can specify a custom heading that the drivetrain should
+ * point toward. This heading reference is profiled for smoothness.
+ */
+class HolonomicDriveController {
+ public:
+  /**
+   * Constructs a holonomic drive controller.
+   *
+   * @param xController     A PID Controller to respond to error in the
+   * field-relative x direction.
+   * @param yController     A PID Controller to respond to error in the
+   * field-relative y direction.
+   * @param thetaController A profiled PID controller to respond to error in
+   * angle.
+   */
+  HolonomicDriveController(
+      const frc2::PIDController& xController,
+      const frc2::PIDController& yController,
+      const ProfiledPIDController<units::radian>& thetaController);
+
+  /**
+   * Returns true if the pose error is within tolerance of the reference.
+   */
+  bool AtReference() const;
+
+  /**
+   * Sets the pose error which is considered tolerable for use with
+   * AtReference().
+   *
+   * @param poseTolerance Pose error which is tolerable.
+   */
+  void SetTolerance(const Pose2d& tolerance);
+
+  /**
+   * Returns the next output of the holonomic drive controller.
+   *
+   * The reference pose, linear velocity, and angular velocity should come from
+   * a drivetrain trajectory.
+   *
+   * @param currentPose        The current pose.
+   * @param poseRef            The desired pose.
+   * @param linearVelocityRef  The desired linear velocity.
+   * @param angleRef           The desired ending angle.
+   */
+  ChassisSpeeds Calculate(const Pose2d& currentPose, const Pose2d& poseRef,
+                          units::meters_per_second_t linearVelocityRef,
+                          const Rotation2d& angleRef);
+
+  /**
+   * Returns the next output of the holonomic drive controller.
+   *
+   * The reference pose, linear velocity, and angular velocity should come from
+   * a drivetrain trajectory.
+   *
+   * @param currentPose  The current pose.
+   * @param desiredState The desired pose, linear velocity, and angular velocity
+   *                     from a trajectory.
+   * @param angleRef     The desired ending angle.
+   */
+  ChassisSpeeds Calculate(const Pose2d& currentPose,
+                          const Trajectory::State& desiredState,
+                          const Rotation2d& angleRef);
+
+  /**
+   * Enables and disables the controller for troubleshooting purposes. When
+   * Calculate() is called on a disabled controller, only feedforward values
+   * are returned.
+   *
+   * @param enabled If the controller is enabled or not.
+   */
+  void SetEnabled(bool enabled);
+
+ private:
+  Pose2d m_poseError;
+  Pose2d m_poseTolerance;
+  bool m_enabled = true;
+
+  frc2::PIDController m_xController;
+  frc2::PIDController m_yController;
+  ProfiledPIDController<units::radian> m_thetaController;
+};
+}  // namespace frc