Add holonomic follower examples (#2052)

wpilibc/src/main/native/cpp/trajectory/constraint/MecanumDriveKinematicsConstraint.cpp

@@ -0,0 +1,35 @@
+/*----------------------------------------------------------------------------*/
+/* 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/trajectory/constraint/MecanumDriveKinematicsConstraint.h"
+
+using namespace frc;
+
+MecanumDriveKinematicsConstraint::MecanumDriveKinematicsConstraint(
+    MecanumDriveKinematics kinematics, units::meters_per_second_t maxSpeed)
+    : m_kinematics(kinematics), m_maxSpeed(maxSpeed) {}
+
+units::meters_per_second_t MecanumDriveKinematicsConstraint::MaxVelocity(
+    const Pose2d& pose, curvature_t curvature,
+    units::meters_per_second_t velocity) {
+  auto xVelocity = velocity * pose.Rotation().Cos();
+  auto yVelocity = velocity * pose.Rotation().Sin();
+  auto wheelSpeeds =
+      m_kinematics.ToWheelSpeeds({xVelocity, yVelocity, velocity * curvature});
+  wheelSpeeds.Normalize(m_maxSpeed);
+
+  auto normSpeeds = m_kinematics.ToChassisSpeeds(wheelSpeeds);
+
+  return units::math::hypot(normSpeeds.vx, normSpeeds.vy);
+}
+
+TrajectoryConstraint::MinMax
+MecanumDriveKinematicsConstraint::MinMaxAcceleration(
+    const Pose2d& pose, curvature_t curvature,
+    units::meters_per_second_t speed) {
+  return {};
+}