Move shared flywheel code into frc971

Signed-off-by: Maxwell Henderson <mxwhenderson@gmail.com>
Change-Id: Ieac317a3e5bc8243e63473f485a2467b74aed348
diff --git a/y2020/control_loops/superstructure/BUILD b/y2020/control_loops/superstructure/BUILD
index 83af834..fc2c0b4 100644
--- a/y2020/control_loops/superstructure/BUILD
+++ b/y2020/control_loops/superstructure/BUILD
@@ -35,6 +35,7 @@
     deps = [
         "//frc971/control_loops:control_loops_ts_fbs",
         "//frc971/control_loops:profiled_subsystem_ts_fbs",
+        "//frc971/control_loops/flywheel:flywheel_controller_status_ts_fbs",
     ],
 )
 
@@ -44,11 +45,12 @@
         "superstructure_status.fbs",
     ],
     gen_reflections = 1,
-    includes = [
-        "//frc971/control_loops:control_loops_fbs_includes",
-        "//frc971/control_loops:profiled_subsystem_fbs_includes",
-    ],
     target_compatible_with = ["@platforms//os:linux"],
+    deps = [
+        "//frc971/control_loops:control_loops_fbs",
+        "//frc971/control_loops:profiled_subsystem_fbs",
+        "//frc971/control_loops/flywheel:flywheel_controller_status_fbs",
+    ],
 )
 
 flatbuffer_cc_library(
@@ -133,6 +135,7 @@
         "//frc971/control_loops:position_sensor_sim",
         "//frc971/control_loops:team_number_test_environment",
         "//frc971/control_loops/drivetrain:drivetrain_status_fbs",
+        "//frc971/control_loops/flywheel:flywheel_test_plant",
         "//y2020/control_loops/superstructure/hood:hood_plants",
         "//y2020/control_loops/superstructure/intake:intake_plants",
         "//y2020/control_loops/superstructure/shooter:shooter_plants",
diff --git a/y2020/control_loops/superstructure/shooter/BUILD b/y2020/control_loops/superstructure/shooter/BUILD
index 4b0bf03..82e9fec 100644
--- a/y2020/control_loops/superstructure/shooter/BUILD
+++ b/y2020/control_loops/superstructure/shooter/BUILD
@@ -20,30 +20,13 @@
     ],
     target_compatible_with = ["@platforms//os:linux"],
     deps = [
-        ":flywheel_controller",
         "//frc971/control_loops:control_loop",
         "//frc971/control_loops:profiled_subsystem",
+        "//frc971/control_loops/flywheel:flywheel_controller",
         "//y2020/control_loops/superstructure:superstructure_goal_fbs",
         "//y2020/control_loops/superstructure:superstructure_output_fbs",
         "//y2020/control_loops/superstructure:superstructure_position_fbs",
         "//y2020/control_loops/superstructure:superstructure_status_fbs",
-    ],
-)
-
-cc_library(
-    name = "flywheel_controller",
-    srcs = [
-        "flywheel_controller.cc",
-    ],
-    hdrs = [
-        "flywheel_controller.h",
-    ],
-    target_compatible_with = ["@platforms//os:linux"],
-    deps = [
-        "//frc971/control_loops:control_loop",
-        "//frc971/control_loops:profiled_subsystem",
-        "//y2020/control_loops/superstructure:superstructure_goal_fbs",
-        "//y2020/control_loops/superstructure:superstructure_status_fbs",
         "//y2020/control_loops/superstructure/accelerator:accelerator_plants",
         "//y2020/control_loops/superstructure/finisher:finisher_plants",
     ],
diff --git a/y2020/control_loops/superstructure/shooter/flywheel_controller.cc b/y2020/control_loops/superstructure/shooter/flywheel_controller.cc
deleted file mode 100644
index a25ed53..0000000
--- a/y2020/control_loops/superstructure/shooter/flywheel_controller.cc
+++ /dev/null
@@ -1,175 +0,0 @@
-#include "y2020/control_loops/superstructure/shooter/flywheel_controller.h"
-
-#include <chrono>
-
-#include "aos/logging/logging.h"
-#include "y2020/control_loops/superstructure/accelerator/accelerator_plant.h"
-#include "y2020/control_loops/superstructure/finisher/finisher_plant.h"
-
-namespace y2020 {
-namespace control_loops {
-namespace superstructure {
-namespace shooter {
-
-// Class to current limit battery current for a flywheel controller.
-class CurrentLimitedStateFeedbackController
-    : public StateFeedbackLoop<3, 1, 1, double,
-                               StateFeedbackHybridPlant<3, 1, 1>,
-                               HybridKalman<3, 1, 1>> {
- public:
-  // Builds a CurrentLimitedStateFeedbackController given the coefficients, bemf
-  // coefficient (units of radians/sec / volt), and motor resistance in ohms.
-  CurrentLimitedStateFeedbackController(
-      StateFeedbackLoop<3, 1, 1, double, StateFeedbackHybridPlant<3, 1, 1>,
-                        HybridKalman<3, 1, 1>> &&other,
-      double bemf, double resistance)
-      : StateFeedbackLoop(std::move(other)),
-        bemf_(bemf),
-        resistance_(resistance) {}
-
-  double resistance() const { return resistance_; }
-  double bemf() const { return bemf_; }
-
-  void CapU() override {
-    const double bemf_voltage = X_hat(1) / bemf_;
-    // Solve the system of equations:
-    //
-    //   motor_current = (u - bemf_voltage) / resistance
-    //   battery_current = ((u - bemf_voltage) / resistance) * u / 12.0
-    //   0.0 = u * u - u * bemf_voltage - max_current * 12.0 * resistance
-    //
-    // And we have a quadratic!
-    const double a = 1;
-    const double b = -bemf_voltage;
-    const double c_positive = -70.0 * 12.0 * resistance_;
-    const double c_negative = -25.0 * 12.0 * resistance_;
-
-    // Root is always positive.
-    const double root_positive = std::sqrt(b * b - 4.0 * a * c_positive);
-    const double root_negative = std::sqrt(b * b - 4.0 * a * c_negative);
-    const double upper_limit = (-b + root_positive) / (2.0 * a);
-    const double lower_limit = (-b - root_negative) / (2.0 * a);
-
-    // Limit to the battery voltage and the current limit voltage.
-    mutable_U(0, 0) = std::clamp(U(0, 0), lower_limit, upper_limit);
-    if (R(1) > 50.0) {
-      mutable_U(0, 0) = std::clamp(U(0, 0), 1.0, 12.0);
-    } else {
-      mutable_U(0, 0) = std::clamp(U(0, 0), 0.0, 12.0);
-    }
-  }
-
- private:
-  double bemf_ = 0.0;
-  double resistance_ = 0.0;
-};
-
-FlywheelController::FlywheelController(
-    StateFeedbackLoop<3, 1, 1, double, StateFeedbackHybridPlant<3, 1, 1>,
-                      HybridKalman<3, 1, 1>> &&loop,
-    double bemf, double resistance)
-    : loop_(new CurrentLimitedStateFeedbackController(std::move(loop), bemf,
-                                                      resistance)) {
-  history_.fill(std::pair<double, ::aos::monotonic_clock::time_point>(
-      0, ::aos::monotonic_clock::epoch()));
-  Y_.setZero();
-}
-
-void FlywheelController::set_goal(double angular_velocity_goal) {
-  loop_->mutable_next_R() << 0.0, angular_velocity_goal, 0.0;
-  last_goal_ = angular_velocity_goal;
-}
-
-void FlywheelController::set_position(
-    double current_position,
-    const aos::monotonic_clock::time_point position_timestamp) {
-  // Project time forwards.
-  const int newest_history_position =
-      ((history_position_ == 0) ? kHistoryLength : history_position_) - 1;
-
-  if (!first_) {
-    loop_->UpdateObserver(
-        loop_->U(),
-        position_timestamp - std::get<1>(history_[newest_history_position]));
-  } else {
-    first_ = false;
-  }
-
-  // Update position in the model.
-  Y_ << current_position;
-
-  // Add the position to the history.
-  history_[history_position_] =
-      std::pair<double, ::aos::monotonic_clock::time_point>(current_position,
-                                                            position_timestamp);
-  history_position_ = (history_position_ + 1) % kHistoryLength;
-
-  loop_->Correct(Y_);
-}
-
-double FlywheelController::voltage() const { return loop_->U(0, 0); }
-
-double FlywheelController::current() const {
-  return ((voltage() - (velocity() / loop_->bemf())) / (loop_->resistance())) *
-         voltage() / 12.0;
-}
-
-void FlywheelController::Update(bool disabled) {
-  loop_->mutable_R() = loop_->next_R();
-  if (loop_->R(1, 0) < 1.0) {
-    // Kill power at low angular velocities.
-    disabled = true;
-  }
-
-  loop_->UpdateController(disabled);
-}
-
-flatbuffers::Offset<FlywheelControllerStatus> FlywheelController::SetStatus(
-    flatbuffers::FlatBufferBuilder *fbb) {
-  // Compute the oldest point in the history.
-  const int oldest_history_position = history_position_;
-  const int newest_history_position =
-      ((history_position_ == 0) ? kHistoryLength : history_position_) - 1;
-  const int second_newest_history_position =
-      ((newest_history_position == 0) ? kHistoryLength
-                                      : newest_history_position) -
-      1;
-
-  const double total_loop_time = ::aos::time::DurationInSeconds(
-      std::get<1>(history_[newest_history_position]) -
-      std::get<1>(history_[oldest_history_position]));
-
-  const double distance_traveled =
-      std::get<0>(history_[newest_history_position]) -
-      std::get<0>(history_[oldest_history_position]);
-
-  const double last_loop_time = ::aos::time::DurationInSeconds(
-      std::get<1>(history_[newest_history_position]) -
-      std::get<1>(history_[second_newest_history_position]));
-
-  const double last_distance_traveled =
-      std::get<0>(history_[newest_history_position]) -
-      std::get<0>(history_[second_newest_history_position]);
-
-  // Compute the distance moved over that time period.
-  avg_angular_velocity_ = (distance_traveled) / (total_loop_time);
-
-  FlywheelControllerStatusBuilder builder(*fbb);
-
-  builder.add_avg_angular_velocity(avg_angular_velocity_);
-  builder.add_dt_angular_velocity(last_distance_traveled / last_loop_time);
-  builder.add_angular_velocity(loop_->X_hat(1, 0));
-  builder.add_voltage_error(loop_->X_hat(2, 0));
-  builder.add_commanded_current(current());
-  builder.add_angular_velocity_goal(last_goal_);
-  return builder.Finish();
-}
-
-FlywheelController::~FlywheelController() {}
-
-double FlywheelController::velocity() const { return loop_->X_hat(1, 0); }
-
-}  // namespace shooter
-}  // namespace superstructure
-}  // namespace control_loops
-}  // namespace y2020
diff --git a/y2020/control_loops/superstructure/shooter/flywheel_controller.h b/y2020/control_loops/superstructure/shooter/flywheel_controller.h
deleted file mode 100644
index 1d56407..0000000
--- a/y2020/control_loops/superstructure/shooter/flywheel_controller.h
+++ /dev/null
@@ -1,83 +0,0 @@
-#ifndef Y2020_CONTROL_LOOPS_SHOOTER_FLYWHEEL_CONTROLLER_H_
-#define Y2020_CONTROL_LOOPS_SHOOTER_FLYWHEEL_CONTROLLER_H_
-
-#include <memory>
-
-#include "aos/time/time.h"
-#include "frc971/control_loops/control_loop.h"
-#include "frc971/control_loops/state_feedback_loop.h"
-#include "y2020/control_loops/superstructure/accelerator/integral_accelerator_plant.h"
-#include "y2020/control_loops/superstructure/finisher/integral_finisher_plant.h"
-#include "y2020/control_loops/superstructure/superstructure_status_generated.h"
-
-namespace y2020 {
-namespace control_loops {
-namespace superstructure {
-namespace shooter {
-
-class CurrentLimitedStateFeedbackController;
-
-// Handles the velocity control of each flywheel.
-class FlywheelController {
- public:
-  FlywheelController(
-      StateFeedbackLoop<3, 1, 1, double, StateFeedbackHybridPlant<3, 1, 1>,
-                        HybridKalman<3, 1, 1>> &&loop,
-      double bemf, double resistance);
-
-  ~FlywheelController();
-
-  // Sets the velocity goal in radians/sec
-  void set_goal(double angular_velocity_goal);
-  double goal() const { return last_goal_; }
-  // Sets the current encoder position in radians
-  void set_position(double current_position,
-                    const aos::monotonic_clock::time_point position_timestamp);
-
-  // Populates the status structure.
-  flatbuffers::Offset<FlywheelControllerStatus> SetStatus(
-      flatbuffers::FlatBufferBuilder *fbb);
-
-  // Returns the control loop calculated voltage.
-  double voltage() const;
-
-  // Returns the expected battery current for the last U.
-  double current() const;
-
-  // Returns the instantaneous velocity.
-  double velocity() const;
-
-  // Executes the control loop for a cycle.
-  void Update(bool disabled);
-
-  double avg_angular_velocity() { return avg_angular_velocity_; }
-
- private:
-  // The current sensor measurement.
-  Eigen::Matrix<double, 1, 1> Y_;
-  // The control loop.
-  ::std::unique_ptr<CurrentLimitedStateFeedbackController> loop_;
-
-  // History array for calculating a filtered angular velocity.
-  static constexpr int kHistoryLength = 10;
-  ::std::array<std::pair<double, ::aos::monotonic_clock::time_point>,
-               kHistoryLength>
-      history_;
-  ptrdiff_t history_position_ = 0;
-
-  // Average velocity logging.
-  double avg_angular_velocity_ = 0;
-
-  double last_goal_ = 0;
-
-  bool first_ = true;
-
-  DISALLOW_COPY_AND_ASSIGN(FlywheelController);
-};
-
-}  // namespace shooter
-}  // namespace superstructure
-}  // namespace control_loops
-}  // namespace y2020
-
-#endif  // Y2020_CONTROL_LOOPS_SHOOTER_FLYWHEEL_CONTROLLER_H_
diff --git a/y2020/control_loops/superstructure/shooter/shooter.cc b/y2020/control_loops/superstructure/shooter/shooter.cc
index 9be6273..c400e34 100644
--- a/y2020/control_loops/superstructure/shooter/shooter.cc
+++ b/y2020/control_loops/superstructure/shooter/shooter.cc
@@ -5,7 +5,9 @@
 
 #include "aos/logging/logging.h"
 #include "y2020/control_loops/superstructure/accelerator/accelerator_plant.h"
+#include "y2020/control_loops/superstructure/accelerator/integral_accelerator_plant.h"
 #include "y2020/control_loops/superstructure/finisher/finisher_plant.h"
+#include "y2020/control_loops/superstructure/finisher/integral_finisher_plant.h"
 
 namespace y2020 {
 namespace control_loops {
@@ -78,11 +80,11 @@
     UpToSpeed(goal);
   }
 
-  flatbuffers::Offset<FlywheelControllerStatus> finisher_status_offset =
-      finisher_.SetStatus(fbb);
-  flatbuffers::Offset<FlywheelControllerStatus> accelerator_left_status_offset =
-      accelerator_left_.SetStatus(fbb);
-  flatbuffers::Offset<FlywheelControllerStatus>
+  flatbuffers::Offset<frc971::control_loops::flywheel::FlywheelControllerStatus>
+      finisher_status_offset = finisher_.SetStatus(fbb);
+  flatbuffers::Offset<frc971::control_loops::flywheel::FlywheelControllerStatus>
+      accelerator_left_status_offset = accelerator_left_.SetStatus(fbb);
+  flatbuffers::Offset<frc971::control_loops::flywheel::FlywheelControllerStatus>
       accelerator_right_status_offset = accelerator_right_.SetStatus(fbb);
 
   ShooterStatusBuilder status_builder(*fbb);
diff --git a/y2020/control_loops/superstructure/shooter/shooter.h b/y2020/control_loops/superstructure/shooter/shooter.h
index ccbb326..a1d7be3 100644
--- a/y2020/control_loops/superstructure/shooter/shooter.h
+++ b/y2020/control_loops/superstructure/shooter/shooter.h
@@ -2,8 +2,8 @@
 #define Y2020_CONTROL_LOOPS_SHOOTER_SHOOTER_H_
 
 #include "frc971/control_loops/control_loop.h"
+#include "frc971/control_loops/flywheel/flywheel_controller.h"
 #include "frc971/control_loops/state_feedback_loop.h"
-#include "y2020/control_loops/superstructure/shooter/flywheel_controller.h"
 #include "y2020/control_loops/superstructure/superstructure_goal_generated.h"
 #include "y2020/control_loops/superstructure/superstructure_output_generated.h"
 #include "y2020/control_loops/superstructure/superstructure_position_generated.h"
@@ -42,7 +42,8 @@
   // flywheel and when it gets shot.
   static constexpr double kMinFinisherVelocityDipWithBall = 5.0;
 
-  FlywheelController finisher_, accelerator_left_, accelerator_right_;
+  frc971::control_loops::flywheel::FlywheelController finisher_,
+      accelerator_left_, accelerator_right_;
 
   void UpToSpeed(const ShooterGoal *goal);
   bool finisher_ready_ = false;
diff --git a/y2020/control_loops/superstructure/superstructure_lib_test.cc b/y2020/control_loops/superstructure/superstructure_lib_test.cc
index d2051df..8b34fc9 100644
--- a/y2020/control_loops/superstructure/superstructure_lib_test.cc
+++ b/y2020/control_loops/superstructure/superstructure_lib_test.cc
@@ -11,6 +11,7 @@
 #include "aos/network/team_number.h"
 #include "frc971/control_loops/capped_test_plant.h"
 #include "frc971/control_loops/control_loop_test.h"
+#include "frc971/control_loops/flywheel/flywheel_test_plant.h"
 #include "frc971/control_loops/position_sensor_sim.h"
 #include "frc971/control_loops/team_number_test_environment.h"
 #include "y2020/constants.h"
@@ -51,39 +52,6 @@
 typedef Superstructure::PotAndAbsoluteEncoderSubsystem
     PotAndAbsoluteEncoderSubsystem;
 
-class FlywheelPlant : public StateFeedbackPlant<2, 1, 1> {
- public:
-  explicit FlywheelPlant(StateFeedbackPlant<2, 1, 1> &&other, double bemf,
-                         double resistance)
-      : StateFeedbackPlant<2, 1, 1>(::std::move(other)),
-        bemf_(bemf),
-        resistance_(resistance) {}
-
-  void CheckU(const Eigen::Matrix<double, 1, 1> &U) override {
-    EXPECT_LE(U(0, 0), U_max(0, 0) + 0.00001 + voltage_offset_);
-    EXPECT_GE(U(0, 0), U_min(0, 0) - 0.00001 + voltage_offset_);
-  }
-
-  double motor_current(const Eigen::Matrix<double, 1, 1> U) const {
-    return (U(0) - X(1) / bemf_) / resistance_;
-  }
-
-  double battery_current(const Eigen::Matrix<double, 1, 1> U) const {
-    return motor_current(U) * U(0) / 12.0;
-  }
-
-  double voltage_offset() const { return voltage_offset_; }
-  void set_voltage_offset(double voltage_offset) {
-    voltage_offset_ = voltage_offset;
-  }
-
- private:
-  double voltage_offset_ = 0.0;
-
-  double bemf_;
-  double resistance_;
-};
-
 // Class which simulates the superstructure and sends out queue messages with
 // the position.
 class SuperstructureSimulation {
@@ -111,14 +79,16 @@
                             .turret.subsystem_params.zeroing_constants
                             .one_revolution_distance),
         accelerator_left_plant_(
-            new FlywheelPlant(accelerator::MakeAcceleratorPlant(),
-                              accelerator::kBemf, accelerator::kResistance)),
+            new frc971::control_loops::flywheel::FlywheelPlant(
+                accelerator::MakeAcceleratorPlant(), accelerator::kBemf,
+                accelerator::kResistance)),
         accelerator_right_plant_(
-            new FlywheelPlant(accelerator::MakeAcceleratorPlant(),
-                              accelerator::kBemf, accelerator::kResistance)),
-        finisher_plant_(new FlywheelPlant(finisher::MakeFinisherPlant(),
-                                          finisher::kBemf,
-                                          finisher::kResistance)) {
+            new frc971::control_loops::flywheel::FlywheelPlant(
+                accelerator::MakeAcceleratorPlant(), accelerator::kBemf,
+                accelerator::kResistance)),
+        finisher_plant_(new frc971::control_loops::flywheel::FlywheelPlant(
+            finisher::MakeFinisherPlant(), finisher::kBemf,
+            finisher::kResistance)) {
     InitializeHoodPosition(constants::Values::kHoodRange().upper);
     InitializeIntakePosition(constants::Values::kIntakeRange().upper);
     InitializeTurretPosition(constants::Values::kTurretRange().middle());
@@ -413,9 +383,12 @@
   ::std::unique_ptr<CappedTestPlant> turret_plant_;
   PositionSensorSimulator turret_encoder_;
 
-  ::std::unique_ptr<FlywheelPlant> accelerator_left_plant_;
-  ::std::unique_ptr<FlywheelPlant> accelerator_right_plant_;
-  ::std::unique_ptr<FlywheelPlant> finisher_plant_;
+  ::std::unique_ptr<frc971::control_loops::flywheel::FlywheelPlant>
+      accelerator_left_plant_;
+  ::std::unique_ptr<frc971::control_loops::flywheel::FlywheelPlant>
+      accelerator_right_plant_;
+  ::std::unique_ptr<frc971::control_loops::flywheel::FlywheelPlant>
+      finisher_plant_;
 
   // The acceleration limits to check for while moving.
   double peak_hood_acceleration_ = 1e10;
diff --git a/y2020/control_loops/superstructure/superstructure_status.fbs b/y2020/control_loops/superstructure/superstructure_status.fbs
index 611661c..d3f98e5 100644
--- a/y2020/control_loops/superstructure/superstructure_status.fbs
+++ b/y2020/control_loops/superstructure/superstructure_status.fbs
@@ -1,5 +1,6 @@
 include "frc971/control_loops/control_loops.fbs";
 include "frc971/control_loops/profiled_subsystem.fbs";
+include "frc971/control_loops/flywheel/flywheel_controller_status.fbs";
 
 namespace y2020.control_loops.superstructure;
 
@@ -9,36 +10,14 @@
   TURRET
 }
 
-table FlywheelControllerStatus {
-  // The current average velocity in radians/second over the last kHistoryLength
-  // in shooter.h
-  avg_angular_velocity:double (id: 0);
-
-  // The current instantaneous filtered velocity in radians/second.
-  angular_velocity:double (id: 1);
-
-  // The target speed selected by the lookup table or from manual override
-  // Can be compared to velocity to determine if ready.
-  angular_velocity_goal:double (id: 2);
-
-  // Voltage error.
-  voltage_error:double (id: 3);
-
-  // The commanded battery current.
-  commanded_current:double (id: 4);
-
-  // The angular velocity of the flywheel computed using delta x / delta t
-  dt_angular_velocity:double (id: 5);
-}
-
 table ShooterStatus {
   // The final wheel shooting the ball
-  finisher:FlywheelControllerStatus (id: 0);
+  finisher:frc971.control_loops.flywheel.FlywheelControllerStatus (id: 0);
 
   // The subsystem to accelerate the ball before the finisher
   // Velocity is the fastest (top) wheel
-  accelerator_left:FlywheelControllerStatus (id: 1);
-  accelerator_right:FlywheelControllerStatus (id: 2);
+  accelerator_left:frc971.control_loops.flywheel.FlywheelControllerStatus (id: 1);
+  accelerator_right:frc971.control_loops.flywheel.FlywheelControllerStatus (id: 2);
 
   // If the shooter is ready, this is true.  Note: don't use this for status
   // checking, only for plotting.  Changes in goal take time to impact this.