Add TrapezoidProfile external PID examples (#2131)

wpilibcExamples/src/main/cpp/examples/ArmBotOffboard/include/subsystems/ArmSubsystem.h

@@ -0,0 +1,30 @@
+/*----------------------------------------------------------------------------*/
+/* 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/controller/ArmFeedforward.h>
+#include <frc2/command/TrapezoidProfileSubsystem.h>
+#include <units/units.h>
+
+#include "ExampleSmartMotorController.h"
+
+/**
+ * A robot arm subsystem that moves with a motion profile.
+ */
+class ArmSubsystem : public frc2::TrapezoidProfileSubsystem<units::radians> {
+  using State = frc::TrapezoidProfile<units::radians>::State;
+
+ public:
+  ArmSubsystem();
+
+  void UseState(State setpoint) override;
+
+ private:
+  ExampleSmartMotorController m_motor;
+  frc::ArmFeedforward m_feedforward;
+};