Add TrapezoidProfile external PID examples (#2131)

wpilibcExamples/src/main/cpp/examples/DriveDistanceOffboard/include/Constants.h

@@ -0,0 +1,46 @@
+/*----------------------------------------------------------------------------*/
+/* 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 <units/units.h>
+#include <wpi/math>
+
+/**
+ * The Constants header provides a convenient place for teams to hold robot-wide
+ * numerical or bool constants.  This should not be used for any other purpose.
+ *
+ * It is generally a good idea to place constants into subsystem- or
+ * command-specific namespaces within this header, which can then be used where
+ * they are needed.
+ */
+
+namespace DriveConstants {
+constexpr int kLeftMotor1Port = 0;
+constexpr int kLeftMotor2Port = 1;
+constexpr int kRightMotor1Port = 2;
+constexpr int kRightMotor2Port = 3;
+
+// These are example values only - DO NOT USE THESE FOR YOUR OWN ROBOT!
+// These characterization values MUST be determined either experimentally or
+// theoretically for *your* robot's drive. The RobotPy Characterization
+// Toolsuite provides a convenient tool for obtaining these values for your
+// robot.
+constexpr auto ks = 1_V;
+constexpr auto kv = 0.8_V * 1_s / 1_m;
+constexpr auto ka = 0.15_V * 1_s * 1_s / 1_m;
+
+constexpr double kp = 1;
+
+constexpr auto kMaxSpeed = 3_mps;
+constexpr auto kMaxAcceleration = 3_mps_sq;
+
+}  // namespace DriveConstants
+
+namespace OIConstants {
+constexpr int kDriverControllerPort = 1;
+}  // namespace OIConstants