Add holonomic follower examples (#2052)

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

@@ -0,0 +1,93 @@
+/*----------------------------------------------------------------------------*/
+/* 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.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include <frc/geometry/Translation2d.h>
+#include <frc/kinematics/MecanumDriveKinematics.h>
+#include <frc/trajectory/TrapezoidProfile.h>
+#include <units/units.h>
+#include <wpi/math>
+
+#pragma once
+
+/**
+ * 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 kFrontLeftMotorPort = 0;
+constexpr int kRearLeftMotorPort = 1;
+constexpr int kFrontRightMotorPort = 2;
+constexpr int kRearRightMotorPort = 3;
+
+constexpr int kFrontLeftEncoderPorts[]{0, 1};
+constexpr int kRearLeftEncoderPorts[]{2, 3};
+constexpr int kFrontRightEncoderPorts[]{4, 5};
+constexpr int kRearRightEncoderPorts[]{5, 6};
+
+constexpr bool kFrontLeftEncoderReversed = false;
+constexpr bool kRearLeftEncoderReversed = true;
+constexpr bool kFrontRightEncoderReversed = false;
+constexpr bool kRearRightEncoderReversed = true;
+
+constexpr auto kTrackWidth =
+    0.5_m;  // Distance between centers of right and left wheels on robot
+constexpr auto kWheelBase =
+    0.7_m;  // Distance between centers of front and back wheels on robot
+extern const frc::MecanumDriveKinematics kDriveKinematics;
+
+constexpr int kEncoderCPR = 1024;
+constexpr double kWheelDiameterMeters = .15;
+constexpr double kEncoderDistancePerPulse =
+    // Assumes the encoders are directly mounted on the wheel shafts
+    (kWheelDiameterMeters * wpi::math::pi) / static_cast<double>(kEncoderCPR);
+
+constexpr bool kGyroReversed = false;
+
+// 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 * 1_V * 1_s / 1_m;
+constexpr auto ka = 0.15 * 1_V * 1_s * 1_s / 1_m;
+
+// Example value only - as above, this must be tuned for your drive!
+constexpr double kPFrontLeftVel = 0.5;
+constexpr double kPRearLeftVel = 0.5;
+constexpr double kPFrontRightVel = 0.5;
+constexpr double kPRearRightVel = 0.5;
+}  // namespace DriveConstants
+
+namespace AutoConstants {
+using radians_per_second_squared_t =
+    units::compound_unit<units::radians,
+                         units::inverse<units::squared<units::second>>>;
+
+constexpr auto kMaxSpeed = units::meters_per_second_t(3);
+constexpr auto kMaxAcceleration = units::meters_per_second_squared_t(3);
+constexpr auto kMaxAngularSpeed = units::radians_per_second_t(3);
+constexpr auto kMaxAngularAcceleration =
+    units::unit_t<radians_per_second_squared_t>(3);
+
+constexpr double kPXController = 0.5;
+constexpr double kPYController = 0.5;
+constexpr double kPThetaController = 0.5;
+
+constexpr frc::TrapezoidProfile<units::radians>::Constraints
+    kThetaControllerConstraints{kMaxAngularSpeed, kMaxAngularAcceleration};
+
+}  // namespace AutoConstants
+
+namespace OIConstants {
+constexpr int kDriverControllerPort = 1;
+}  // namespace OIConstants