[wpimath] Refactor WheelVoltages inner class to a separate file (#4203)

wpimath/src/main/java/edu/wpi/first/math/controller/DifferentialDriveAccelerationLimiter.java

@@ -21,20 +21,6 @@ public class DifferentialDriveAccelerationLimiter {
   private final double m_maxLinearAccel;
   private final double m_maxAngularAccel;
 
-  /** Motor voltages for a differential drive. */
-  @SuppressWarnings("MemberName")
-  public static class WheelVoltages {
-    public double left;
-    public double right;
-
-    private WheelVoltages() {}
-
-    public WheelVoltages(double left, double right) {
-      this.left = left;
-      this.right = right;
-    }
-  }
-
   /**
    * Constructs a DifferentialDriveAccelerationLimiter.
    *
@@ -64,7 +50,7 @@ public class DifferentialDriveAccelerationLimiter {
    * @return The constrained wheel voltages.
    */
   @SuppressWarnings("LocalVariableName")
-  public WheelVoltages calculate(
+  public DifferentialDriveWheelVoltages calculate(
       double leftVelocity, double rightVelocity, double leftVoltage, double rightVoltage) {
     var u = new MatBuilder<>(Nat.N2(), Nat.N1()).fill(leftVoltage, rightVoltage);
 
@@ -99,6 +85,6 @@ public class DifferentialDriveAccelerationLimiter {
     // u = B⁻¹(dx/dt - Ax)
     u = m_system.getB().solve(dxdt.minus(m_system.getA().times(x)));
 
-    return new WheelVoltages(u.get(0, 0), u.get(1, 0));
+    return new DifferentialDriveWheelVoltages(u.get(0, 0), u.get(1, 0));
   }
 }

wpimath/src/main/java/edu/wpi/first/math/controller/DifferentialDriveWheelVoltages.java

@@ -0,0 +1,19 @@
+// 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.
+
+package edu.wpi.first.math.controller;
+
+/** Motor voltages for a differential drive. */
+@SuppressWarnings("MemberName")
+public class DifferentialDriveWheelVoltages {
+  public double left;
+  public double right;
+
+  public DifferentialDriveWheelVoltages() {}
+
+  public DifferentialDriveWheelVoltages(double left, double right) {
+    this.left = left;
+    this.right = right;
+  }
+}

wpimath/src/main/java/edu/wpi/first/math/controller/LTVDifferentialDriveController.java

@@ -37,20 +37,6 @@ public class LTVDifferentialDriveController {
   private Matrix<N5, N1> m_error = new Matrix<>(Nat.N5(), Nat.N1());
   private Matrix<N5, N1> m_tolerance = new Matrix<>(Nat.N5(), Nat.N1());
 
-  /** Motor voltages for a differential drive. */
-  @SuppressWarnings("MemberName")
-  public static class WheelVoltages {
-    public double left;
-    public double right;
-
-    public WheelVoltages() {}
-
-    public WheelVoltages(double left, double right) {
-      this.left = left;
-      this.right = right;
-    }
-  }
-
   /** States of the drivetrain system. */
   enum State {
     kX(0),
@@ -204,7 +190,7 @@ public class LTVDifferentialDriveController {
    * @return Left and right output voltages of the LTV controller.
    */
   @SuppressWarnings("LocalVariableName")
-  public WheelVoltages calculate(
+  public DifferentialDriveWheelVoltages calculate(
       Pose2d currentPose,
       double leftVelocity,
       double rightVelocity,
@@ -245,7 +231,7 @@ public class LTVDifferentialDriveController {
 
     var u = K.times(inRobotFrame).times(m_error);
 
-    return new WheelVoltages(u.get(0, 0), u.get(1, 0));
+    return new DifferentialDriveWheelVoltages(u.get(0, 0), u.get(1, 0));
   }
 
   /**
@@ -260,7 +246,7 @@ public class LTVDifferentialDriveController {
    * @param desiredState The desired pose, linear velocity, and angular velocity from a trajectory.
    * @return The left and right output voltages of the LTV controller.
    */
-  public WheelVoltages calculate(
+  public DifferentialDriveWheelVoltages calculate(
       Pose2d currentPose,
       double leftVelocity,
       double rightVelocity,

wpimath/src/main/native/cpp/controller/DifferentialDriveAccelerationLimiter.cpp

@@ -19,8 +19,7 @@ DifferentialDriveAccelerationLimiter::DifferentialDriveAccelerationLimiter(
       m_maxLinearAccel{maxLinearAccel},
       m_maxAngularAccel{maxAngularAccel} {}
 
-DifferentialDriveAccelerationLimiter::WheelVoltages
-DifferentialDriveAccelerationLimiter::Calculate(
+DifferentialDriveWheelVoltages DifferentialDriveAccelerationLimiter::Calculate(
     units::meters_per_second_t leftVelocity,
     units::meters_per_second_t rightVelocity, units::volt_t leftVoltage,
     units::volt_t rightVoltage) {

wpimath/src/main/native/cpp/controller/LTVDifferentialDriveController.cpp

@@ -94,8 +94,7 @@ void LTVDifferentialDriveController::SetTolerance(
                  leftVelocityTolerance.value(), rightVelocityTolerance.value()};
 }
 
-LTVDifferentialDriveController::WheelVoltages
-LTVDifferentialDriveController::Calculate(
+DifferentialDriveWheelVoltages LTVDifferentialDriveController::Calculate(
     const Pose2d& currentPose, units::meters_per_second_t leftVelocity,
     units::meters_per_second_t rightVelocity, const Pose2d& poseRef,
     units::meters_per_second_t leftVelocityRef,
@@ -124,11 +123,11 @@ LTVDifferentialDriveController::Calculate(
 
   Vectord<2> u = K * inRobotFrame * m_error;
 
-  return WheelVoltages{units::volt_t{u(0)}, units::volt_t{u(1)}};
+  return DifferentialDriveWheelVoltages{units::volt_t{u(0)},
+                                        units::volt_t{u(1)}};
 }
 
-LTVDifferentialDriveController::WheelVoltages
-LTVDifferentialDriveController::Calculate(
+DifferentialDriveWheelVoltages LTVDifferentialDriveController::Calculate(
     const Pose2d& currentPose, units::meters_per_second_t leftVelocity,
     units::meters_per_second_t rightVelocity,
     const Trajectory::State& desiredState) {

wpimath/src/main/native/include/frc/controller/DifferentialDriveAccelerationLimiter.h

@@ -7,6 +7,7 @@
 #include <wpi/SymbolExports.h>
 
 #include "Eigen/Core"
+#include "frc/controller/DifferentialDriveWheelVoltages.h"
 #include "frc/system/LinearSystem.h"
 #include "units/acceleration.h"
 #include "units/angular_acceleration.h"
@@ -25,14 +26,6 @@ namespace frc {
  */
 class WPILIB_DLLEXPORT DifferentialDriveAccelerationLimiter {
  public:
-  /**
-   * Motor voltages for a differential drive.
-   */
-  struct WheelVoltages {
-    units::volt_t left = 0_V;
-    units::volt_t right = 0_V;
-  };
-
   /**
    * Constructs a DifferentialDriveAccelerationLimiter.
    *
@@ -55,10 +48,10 @@ class WPILIB_DLLEXPORT DifferentialDriveAccelerationLimiter {
    * @param rightVoltage The unconstrained right motor voltage.
    * @return The constrained wheel voltages.
    */
-  WheelVoltages Calculate(units::meters_per_second_t leftVelocity,
-                          units::meters_per_second_t rightVelocity,
-                          units::volt_t leftVoltage,
-                          units::volt_t rightVoltage);
+  DifferentialDriveWheelVoltages Calculate(
+      units::meters_per_second_t leftVelocity,
+      units::meters_per_second_t rightVelocity, units::volt_t leftVoltage,
+      units::volt_t rightVoltage);
 
  private:
   LinearSystem<2, 2, 2> m_system;

wpimath/src/main/native/include/frc/controller/DifferentialDriveWheelVoltages.h

@@ -0,0 +1,19 @@
+// 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 "units/voltage.h"
+
+namespace frc {
+
+/**
+ * Motor voltages for a differential drive.
+ */
+struct DifferentialDriveWheelVoltages {
+  units::volt_t left = 0_V;
+  units::volt_t right = 0_V;
+};
+
+}  // namespace frc

wpimath/src/main/native/include/frc/controller/LTVDifferentialDriveController.h

@@ -9,6 +9,7 @@
 #include <wpi/interpolating_map.h>
 
 #include "frc/EigenCore.h"
+#include "frc/controller/DifferentialDriveWheelVoltages.h"
 #include "frc/geometry/Pose2d.h"
 #include "frc/system/LinearSystem.h"
 #include "frc/trajectory/Trajectory.h"
@@ -31,14 +32,6 @@ namespace frc {
  */
 class WPILIB_DLLEXPORT LTVDifferentialDriveController {
  public:
-  /**
-   * Motor voltages for a differential drive.
-   */
-  struct WheelVoltages {
-    units::volt_t left = 0_V;
-    units::volt_t right = 0_V;
-  };
-
   /**
    * Constructs a linear time-varying differential drive controller.
    *
@@ -95,12 +88,11 @@ class WPILIB_DLLEXPORT LTVDifferentialDriveController {
    * @param leftVelocityRef  The desired left velocity.
    * @param rightVelocityRef The desired right velocity.
    */
-  WheelVoltages Calculate(const Pose2d& currentPose,
-                          units::meters_per_second_t leftVelocity,
-                          units::meters_per_second_t rightVelocity,
-                          const Pose2d& poseRef,
-                          units::meters_per_second_t leftVelocityRef,
-                          units::meters_per_second_t rightVelocityRef);
+  DifferentialDriveWheelVoltages Calculate(
+      const Pose2d& currentPose, units::meters_per_second_t leftVelocity,
+      units::meters_per_second_t rightVelocity, const Pose2d& poseRef,
+      units::meters_per_second_t leftVelocityRef,
+      units::meters_per_second_t rightVelocityRef);
 
   /**
    * Returns the left and right output voltages of the LTV controller.
@@ -114,10 +106,10 @@ class WPILIB_DLLEXPORT LTVDifferentialDriveController {
    * @param desiredState The desired pose, linear velocity, and angular velocity
    *                     from a trajectory.
    */
-  WheelVoltages Calculate(const Pose2d& currentPose,
-                          units::meters_per_second_t leftVelocity,
-                          units::meters_per_second_t rightVelocity,
-                          const Trajectory::State& desiredState);
+  DifferentialDriveWheelVoltages Calculate(
+      const Pose2d& currentPose, units::meters_per_second_t leftVelocity,
+      units::meters_per_second_t rightVelocity,
+      const Trajectory::State& desiredState);
 
  private:
   units::meter_t m_trackwidth;