diff --git a/y2015/control_loops/drivetrain/drivetrain.cc b/y2015/control_loops/drivetrain/drivetrain.cc
new file mode 100644
index 0000000..22a5d48
--- /dev/null
+++ b/y2015/control_loops/drivetrain/drivetrain.cc
@@ -0,0 +1,777 @@
+#include "y2015/control_loops/drivetrain/drivetrain.h"
+
+#include <stdio.h>
+#include <sched.h>
+#include <cmath>
+#include <memory>
+#include "Eigen/Dense"
+
+#include "aos/common/logging/logging.h"
+#include "aos/common/controls/polytope.h"
+#include "aos/common/commonmath.h"
+#include "aos/common/logging/queue_logging.h"
+#include "aos/common/logging/matrix_logging.h"
+
+#include "y2015/constants.h"
+#include "frc971/control_loops/state_feedback_loop.h"
+#include "frc971/control_loops/coerce_goal.h"
+#include "y2015/control_loops/drivetrain/polydrivetrain_cim_plant.h"
+#include "y2015/control_loops/drivetrain/drivetrain.q.h"
+#include "frc971/queues/gyro.q.h"
+#include "frc971/shifter_hall_effect.h"
+
+// A consistent way to mark code that goes away without shifters. It's still
+// here because we will have shifters again in the future.
+#define HAVE_SHIFTERS 0
+
+using frc971::sensors::gyro_reading;
+
+namespace frc971 {
+namespace control_loops {
+
+class DrivetrainMotorsSS {
+ public:
+  class LimitedDrivetrainLoop : public StateFeedbackLoop<4, 2, 2> {
+   public:
+    LimitedDrivetrainLoop(StateFeedbackLoop<4, 2, 2> &&loop)
+        : StateFeedbackLoop<4, 2, 2>(::std::move(loop)),
+        U_Poly_((Eigen::Matrix<double, 4, 2>() << 1, 0,
+                 -1, 0,
+                 0, 1,
+                 0, -1).finished(),
+                (Eigen::Matrix<double, 4, 1>() << 12.0, 12.0,
+                 12.0, 12.0).finished()) {
+      ::aos::controls::HPolytope<0>::Init();
+      T << 1, -1, 1, 1;
+      T_inverse = T.inverse();
+    }
+
+    bool output_was_capped() const {
+      return output_was_capped_;
+    }
+
+   private:
+    virtual void CapU() {
+      const Eigen::Matrix<double, 4, 1> error = R() - X_hat();
+
+      if (::std::abs(U(0, 0)) > 12.0 || ::std::abs(U(1, 0)) > 12.0) {
+        mutable_U() =
+            U() * 12.0 / ::std::max(::std::abs(U(0, 0)), ::std::abs(U(1, 0)));
+        LOG_MATRIX(DEBUG, "U is now", U());
+        // TODO(Austin): Figure out why the polytope stuff wasn't working and
+        // remove this hack.
+        output_was_capped_ = true;
+        return;
+
+        LOG_MATRIX(DEBUG, "U at start", U());
+        LOG_MATRIX(DEBUG, "R at start", R());
+        LOG_MATRIX(DEBUG, "Xhat at start", X_hat());
+
+        Eigen::Matrix<double, 2, 2> position_K;
+        position_K << K(0, 0), K(0, 2),
+                   K(1, 0), K(1, 2);
+        Eigen::Matrix<double, 2, 2> velocity_K;
+        velocity_K << K(0, 1), K(0, 3),
+                   K(1, 1), K(1, 3);
+
+        Eigen::Matrix<double, 2, 1> position_error;
+        position_error << error(0, 0), error(2, 0);
+        const auto drive_error = T_inverse * position_error;
+        Eigen::Matrix<double, 2, 1> velocity_error;
+        velocity_error << error(1, 0), error(3, 0);
+        LOG_MATRIX(DEBUG, "error", error);
+
+        const auto &poly = U_Poly_;
+        const Eigen::Matrix<double, 4, 2> pos_poly_H =
+            poly.H() * position_K * T;
+        const Eigen::Matrix<double, 4, 1> pos_poly_k =
+            poly.k() - poly.H() * velocity_K * velocity_error;
+        const ::aos::controls::HPolytope<2> pos_poly(pos_poly_H, pos_poly_k);
+
+        Eigen::Matrix<double, 2, 1> adjusted_pos_error;
+        {
+          const auto &P = drive_error;
+
+          Eigen::Matrix<double, 1, 2> L45;
+          L45 << ::aos::sign(P(1, 0)), -::aos::sign(P(0, 0));
+          const double w45 = 0;
+
+          Eigen::Matrix<double, 1, 2> LH;
+          if (::std::abs(P(0, 0)) > ::std::abs(P(1, 0))) {
+            LH << 0, 1;
+          } else {
+            LH << 1, 0;
+          }
+          const double wh = LH.dot(P);
+
+          Eigen::Matrix<double, 2, 2> standard;
+          standard << L45, LH;
+          Eigen::Matrix<double, 2, 1> W;
+          W << w45, wh;
+          const Eigen::Matrix<double, 2, 1> intersection =
+              standard.inverse() * W;
+
+          bool is_inside_h;
+          const auto adjusted_pos_error_h =
+              DoCoerceGoal(pos_poly, LH, wh, drive_error, &is_inside_h);
+          const auto adjusted_pos_error_45 =
+              DoCoerceGoal(pos_poly, L45, w45, intersection, nullptr);
+          if (pos_poly.IsInside(intersection)) {
+            adjusted_pos_error = adjusted_pos_error_h;
+          } else {
+            if (is_inside_h) {
+              if (adjusted_pos_error_h.norm() > adjusted_pos_error_45.norm()) {
+                adjusted_pos_error = adjusted_pos_error_h;
+              } else {
+                adjusted_pos_error = adjusted_pos_error_45;
+              }
+            } else {
+              adjusted_pos_error = adjusted_pos_error_45;
+            }
+          }
+        }
+
+        LOG_MATRIX(DEBUG, "adjusted_pos_error", adjusted_pos_error);
+        mutable_U() =
+            velocity_K * velocity_error + position_K * T * adjusted_pos_error;
+        LOG_MATRIX(DEBUG, "U is now", U());
+      } else {
+        output_was_capped_ = false;
+      }
+    }
+
+    const ::aos::controls::HPolytope<2> U_Poly_;
+    Eigen::Matrix<double, 2, 2> T, T_inverse;
+    bool output_was_capped_ = false;;
+  };
+
+  DrivetrainMotorsSS()
+      : loop_(new LimitedDrivetrainLoop(
+            constants::GetValues().make_drivetrain_loop())),
+        filtered_offset_(0.0),
+        gyro_(0.0),
+        left_goal_(0.0),
+        right_goal_(0.0),
+        raw_left_(0.0),
+        raw_right_(0.0) {
+    // Low gear on both.
+    loop_->set_controller_index(0);
+  }
+
+  void SetGoal(double left, double left_velocity, double right,
+               double right_velocity) {
+    left_goal_ = left;
+    right_goal_ = right;
+    loop_->mutable_R() << left, left_velocity, right, right_velocity;
+  }
+  void SetRawPosition(double left, double right) {
+    raw_right_ = right;
+    raw_left_ = left;
+    Eigen::Matrix<double, 2, 1> Y;
+    Y << left + filtered_offset_, right - filtered_offset_;
+    loop_->Correct(Y);
+  }
+  void SetPosition(double left, double right, double gyro) {
+    // Decay the offset quickly because this gyro is great.
+    const double offset =
+        (right - left - gyro * constants::GetValues().turn_width) / 2.0;
+    filtered_offset_ = 0.25 * offset + 0.75 * filtered_offset_;
+    gyro_ = gyro;
+    SetRawPosition(left, right);
+  }
+
+  void SetExternalMotors(double left_voltage, double right_voltage) {
+    loop_->mutable_U() << left_voltage, right_voltage;
+  }
+
+  void Update(bool stop_motors, bool enable_control_loop) {
+    if (enable_control_loop) {
+      loop_->Update(stop_motors);
+    } else {
+      if (stop_motors) {
+        loop_->mutable_U().setZero();
+        loop_->mutable_U_uncapped().setZero();
+      }
+      loop_->UpdateObserver();
+    }
+    ::Eigen::Matrix<double, 4, 1> E = loop_->R() - loop_->X_hat();
+    LOG_MATRIX(DEBUG, "E", E);
+  }
+
+  double GetEstimatedRobotSpeed() const {
+    // lets just call the average of left and right velocities close enough
+    return (loop_->X_hat(1, 0) + loop_->X_hat(3, 0)) / 2;
+  }
+
+  double GetEstimatedLeftEncoder() const {
+    return loop_->X_hat(0, 0);
+  }
+
+  double GetEstimatedRightEncoder() const {
+    return loop_->X_hat(2, 0);
+  }
+
+  bool OutputWasCapped() const {
+    return loop_->output_was_capped();
+  }
+
+  void SendMotors(DrivetrainQueue::Output *output) const {
+    if (output) {
+      output->left_voltage = loop_->U(0, 0);
+      output->right_voltage = loop_->U(1, 0);
+      output->left_high = false;
+      output->right_high = false;
+    }
+  }
+
+  const LimitedDrivetrainLoop &loop() const { return *loop_; }
+
+ private:
+  ::std::unique_ptr<LimitedDrivetrainLoop> loop_;
+
+  double filtered_offset_;
+  double gyro_;
+  double left_goal_;
+  double right_goal_;
+  double raw_left_;
+  double raw_right_;
+};
+
+class PolyDrivetrain {
+ public:
+
+  enum Gear {
+    HIGH,
+    LOW,
+    SHIFTING_UP,
+    SHIFTING_DOWN
+  };
+  // Stall Torque in N m
+  static constexpr double kStallTorque = 2.42;
+  // Stall Current in Amps
+  static constexpr double kStallCurrent = 133.0;
+  // Free Speed in RPM. Used number from last year.
+  static constexpr double kFreeSpeed = 4650.0;
+  // Free Current in Amps
+  static constexpr double kFreeCurrent = 2.7;
+  // Moment of inertia of the drivetrain in kg m^2
+  // Just borrowed from last year.
+  static constexpr double J = 10;
+  // Mass of the robot, in kg.
+  static constexpr double m = 68;
+  // Radius of the robot, in meters (from last year).
+  static constexpr double rb = 0.9603 / 2.0;
+  static constexpr double kWheelRadius = 0.0515938;
+  // Resistance of the motor, divided by the number of motors.
+  static constexpr double kR = (12.0 / kStallCurrent / 2 + 0.03) / (0.93 * 0.93);
+  // Motor velocity constant
+  static constexpr double Kv =
+      ((kFreeSpeed / 60.0 * 2.0 * M_PI) / (12.0 - kR * kFreeCurrent));
+  // Torque constant
+  static constexpr double Kt = kStallTorque / kStallCurrent;
+
+  PolyDrivetrain()
+      : U_Poly_((Eigen::Matrix<double, 4, 2>() << /*[[*/ 1, 0 /*]*/,
+                 /*[*/ -1, 0 /*]*/,
+                 /*[*/ 0, 1 /*]*/,
+                 /*[*/ 0, -1 /*]]*/).finished(),
+                (Eigen::Matrix<double, 4, 1>() << /*[[*/ 12 /*]*/,
+                 /*[*/ 12 /*]*/,
+                 /*[*/ 12 /*]*/,
+                 /*[*/ 12 /*]]*/).finished()),
+        loop_(new StateFeedbackLoop<2, 2, 2>(
+            constants::GetValues().make_v_drivetrain_loop())),
+        ttrust_(1.1),
+        wheel_(0.0),
+        throttle_(0.0),
+        quickturn_(false),
+        stale_count_(0),
+        position_time_delta_(0.01),
+        left_gear_(LOW),
+        right_gear_(LOW),
+        counter_(0) {
+
+    last_position_.Zero();
+    position_.Zero();
+  }
+  static bool IsInGear(Gear gear) { return gear == LOW || gear == HIGH; }
+
+  static double MotorSpeed(const constants::ShifterHallEffect &hall_effect,
+                           double shifter_position, double velocity) {
+    // TODO(austin): G_high, G_low and kWheelRadius
+    const double avg_hall_effect =
+        (hall_effect.clear_high + hall_effect.clear_low) / 2.0;
+
+    if (shifter_position > avg_hall_effect) {
+      return velocity / constants::GetValues().high_gear_ratio / kWheelRadius;
+    } else {
+      return velocity / constants::GetValues().low_gear_ratio / kWheelRadius;
+    }
+  }
+
+  Gear ComputeGear(const constants::ShifterHallEffect &hall_effect,
+                   double velocity, Gear current) {
+    const double low_omega = MotorSpeed(hall_effect, 0.0, ::std::abs(velocity));
+    const double high_omega =
+        MotorSpeed(hall_effect, 1.0, ::std::abs(velocity));
+
+    double high_torque = ((12.0 - high_omega / Kv) * Kt / kR);
+    double low_torque = ((12.0 - low_omega / Kv) * Kt / kR);
+    double high_power = high_torque * high_omega;
+    double low_power = low_torque * low_omega;
+
+    // TODO(aschuh): Do this right!
+    if ((current == HIGH || high_power > low_power + 160) &&
+        ::std::abs(velocity) > 0.14) {
+      return HIGH;
+    } else {
+      return LOW;
+    }
+  }
+
+  void SetGoal(double wheel, double throttle, bool quickturn, bool highgear) {
+    const double kWheelNonLinearity = 0.5;
+    // Apply a sin function that's scaled to make it feel better.
+    const double angular_range = M_PI_2 * kWheelNonLinearity;
+
+    wheel_ = sin(angular_range * wheel) / sin(angular_range);
+    wheel_ = sin(angular_range * wheel_) / sin(angular_range);
+    wheel_ *= 2.3;
+    quickturn_ = quickturn;
+
+    static const double kThrottleDeadband = 0.05;
+    if (::std::abs(throttle) < kThrottleDeadband) {
+      throttle_ = 0;
+    } else {
+      throttle_ = copysign((::std::abs(throttle) - kThrottleDeadband) /
+                           (1.0 - kThrottleDeadband), throttle);
+    }
+
+    // TODO(austin): Fix the upshift logic to include states.
+    Gear requested_gear;
+    if (false) {
+      const auto &values = constants::GetValues();
+      const double current_left_velocity =
+          (position_.left_encoder - last_position_.left_encoder) /
+          position_time_delta_;
+      const double current_right_velocity =
+          (position_.right_encoder - last_position_.right_encoder) /
+          position_time_delta_;
+
+      Gear left_requested =
+          ComputeGear(values.left_drive, current_left_velocity, left_gear_);
+      Gear right_requested =
+          ComputeGear(values.right_drive, current_right_velocity, right_gear_);
+      requested_gear =
+          (left_requested == HIGH || right_requested == HIGH) ? HIGH : LOW;
+    } else {
+      requested_gear = highgear ? HIGH : LOW;
+    }
+
+    const Gear shift_up =
+        constants::GetValues().clutch_transmission ? HIGH : SHIFTING_UP;
+    const Gear shift_down =
+        constants::GetValues().clutch_transmission ? LOW : SHIFTING_DOWN;
+
+    if (left_gear_ != requested_gear) {
+      if (IsInGear(left_gear_)) {
+        if (requested_gear == HIGH) {
+          left_gear_ = shift_up;
+        } else {
+          left_gear_ = shift_down;
+        }
+      } else {
+        if (requested_gear == HIGH && left_gear_ == SHIFTING_DOWN) {
+          left_gear_ = SHIFTING_UP;
+        } else if (requested_gear == LOW && left_gear_ == SHIFTING_UP) {
+          left_gear_ = SHIFTING_DOWN;
+        }
+      }
+    }
+    if (right_gear_ != requested_gear) {
+      if (IsInGear(right_gear_)) {
+        if (requested_gear == HIGH) {
+          right_gear_ = shift_up;
+        } else {
+          right_gear_ = shift_down;
+        }
+      } else {
+        if (requested_gear == HIGH && right_gear_ == SHIFTING_DOWN) {
+          right_gear_ = SHIFTING_UP;
+        } else if (requested_gear == LOW && right_gear_ == SHIFTING_UP) {
+          right_gear_ = SHIFTING_DOWN;
+        }
+      }
+    }
+  }
+  void SetPosition(const DrivetrainQueue::Position *position) {
+    const auto &values = constants::GetValues();
+    if (position == NULL) {
+      ++stale_count_;
+    } else {
+      last_position_ = position_;
+      position_ = *position;
+      position_time_delta_ = (stale_count_ + 1) * 0.01;
+      stale_count_ = 0;
+    }
+
+#if HAVE_SHIFTERS
+    if (position) {
+      GearLogging gear_logging;
+      // Switch to the correct controller.
+      const double left_middle_shifter_position =
+          (values.left_drive.clear_high + values.left_drive.clear_low) / 2.0;
+      const double right_middle_shifter_position =
+          (values.right_drive.clear_high + values.right_drive.clear_low) / 2.0;
+
+      if (position->left_shifter_position < left_middle_shifter_position ||
+          left_gear_ == LOW) {
+        if (position->right_shifter_position < right_middle_shifter_position ||
+            right_gear_ == LOW) {
+          gear_logging.left_loop_high = false;
+          gear_logging.right_loop_high = false;
+          loop_->set_controller_index(gear_logging.controller_index = 0);
+        } else {
+          gear_logging.left_loop_high = false;
+          gear_logging.right_loop_high = true;
+          loop_->set_controller_index(gear_logging.controller_index = 1);
+        }
+      } else {
+        if (position->right_shifter_position < right_middle_shifter_position ||
+            right_gear_ == LOW) {
+          gear_logging.left_loop_high = true;
+          gear_logging.right_loop_high = false;
+          loop_->set_controller_index(gear_logging.controller_index = 2);
+        } else {
+          gear_logging.left_loop_high = true;
+          gear_logging.right_loop_high = true;
+          loop_->set_controller_index(gear_logging.controller_index = 3);
+        }
+      }
+
+      // TODO(austin): Constants.
+      if (position->left_shifter_position > values.left_drive.clear_high && left_gear_ == SHIFTING_UP) {
+        left_gear_ = HIGH;
+      }
+      if (position->left_shifter_position < values.left_drive.clear_low && left_gear_ == SHIFTING_DOWN) {
+        left_gear_ = LOW;
+      }
+      if (position->right_shifter_position > values.right_drive.clear_high && right_gear_ == SHIFTING_UP) {
+        right_gear_ = HIGH;
+      }
+      if (position->right_shifter_position < values.right_drive.clear_low && right_gear_ == SHIFTING_DOWN) {
+        right_gear_ = LOW;
+      }
+
+      gear_logging.left_state = left_gear_;
+      gear_logging.right_state = right_gear_;
+      LOG_STRUCT(DEBUG, "state", gear_logging);
+    }
+#else
+    (void) values;
+#endif
+  }
+
+  double FilterVelocity(double throttle) {
+    const Eigen::Matrix<double, 2, 2> FF =
+        loop_->B().inverse() *
+        (Eigen::Matrix<double, 2, 2>::Identity() - loop_->A());
+
+    constexpr int kHighGearController = 3;
+    const Eigen::Matrix<double, 2, 2> FF_high =
+        loop_->controller(kHighGearController).plant.B().inverse() *
+        (Eigen::Matrix<double, 2, 2>::Identity() -
+         loop_->controller(kHighGearController).plant.A());
+
+    ::Eigen::Matrix<double, 1, 2> FF_sum = FF.colwise().sum();
+    int min_FF_sum_index;
+    const double min_FF_sum = FF_sum.minCoeff(&min_FF_sum_index);
+    const double min_K_sum = loop_->K().col(min_FF_sum_index).sum();
+    const double high_min_FF_sum = FF_high.col(0).sum();
+
+    const double adjusted_ff_voltage = ::aos::Clip(
+        throttle * 12.0 * min_FF_sum / high_min_FF_sum, -12.0, 12.0);
+    return (adjusted_ff_voltage +
+            ttrust_ * min_K_sum * (loop_->X_hat(0, 0) + loop_->X_hat(1, 0)) /
+                2.0) /
+           (ttrust_ * min_K_sum + min_FF_sum);
+  }
+
+  double MaxVelocity() {
+    const Eigen::Matrix<double, 2, 2> FF =
+        loop_->B().inverse() *
+        (Eigen::Matrix<double, 2, 2>::Identity() - loop_->A());
+
+    constexpr int kHighGearController = 3;
+    const Eigen::Matrix<double, 2, 2> FF_high =
+        loop_->controller(kHighGearController).plant.B().inverse() *
+        (Eigen::Matrix<double, 2, 2>::Identity() -
+         loop_->controller(kHighGearController).plant.A());
+
+    ::Eigen::Matrix<double, 1, 2> FF_sum = FF.colwise().sum();
+    int min_FF_sum_index;
+    const double min_FF_sum = FF_sum.minCoeff(&min_FF_sum_index);
+    //const double min_K_sum = loop_->K().col(min_FF_sum_index).sum();
+    const double high_min_FF_sum = FF_high.col(0).sum();
+
+    const double adjusted_ff_voltage = ::aos::Clip(
+        12.0 * min_FF_sum / high_min_FF_sum, -12.0, 12.0);
+    return adjusted_ff_voltage / min_FF_sum;
+  }
+
+  void Update() {
+    const auto &values = constants::GetValues();
+    // TODO(austin): Observer for the current velocity instead of difference
+    // calculations.
+    ++counter_;
+#if HAVE_SHIFTERS
+    const double current_left_velocity =
+        (position_.left_encoder - last_position_.left_encoder) /
+        position_time_delta_;
+    const double current_right_velocity =
+        (position_.right_encoder - last_position_.right_encoder) /
+        position_time_delta_;
+    const double left_motor_speed =
+        MotorSpeed(values.left_drive, position_.left_shifter_position,
+                   current_left_velocity);
+    const double right_motor_speed =
+        MotorSpeed(values.right_drive, position_.right_shifter_position,
+                   current_right_velocity);
+
+    {
+      CIMLogging logging;
+
+      // Reset the CIM model to the current conditions to be ready for when we
+      // shift.
+      if (IsInGear(left_gear_)) {
+        logging.left_in_gear = true;
+      } else {
+        logging.left_in_gear = false;
+      }
+      logging.left_motor_speed = left_motor_speed;
+      logging.left_velocity = current_left_velocity;
+      if (IsInGear(right_gear_)) {
+        logging.right_in_gear = true;
+      } else {
+        logging.right_in_gear = false;
+      }
+      logging.right_motor_speed = right_motor_speed;
+      logging.right_velocity = current_right_velocity;
+
+      LOG_STRUCT(DEBUG, "currently", logging);
+    }
+#else
+    (void) values;
+#endif
+
+#if HAVE_SHIFTERS
+    if (IsInGear(left_gear_) && IsInGear(right_gear_)) {
+#else
+    {
+#endif
+      // FF * X = U (steady state)
+      const Eigen::Matrix<double, 2, 2> FF =
+          loop_->B().inverse() *
+          (Eigen::Matrix<double, 2, 2>::Identity() - loop_->A());
+
+      // Invert the plant to figure out how the velocity filter would have to
+      // work
+      // out in order to filter out the forwards negative inertia.
+      // This math assumes that the left and right power and velocity are
+      // equals,
+      // and that the plant is the same on the left and right.
+      const double fvel = FilterVelocity(throttle_);
+
+      const double sign_svel = wheel_ * ((fvel > 0.0) ? 1.0 : -1.0);
+      double steering_velocity;
+      if (quickturn_) {
+        steering_velocity = wheel_ * MaxVelocity();
+      } else {
+        steering_velocity = ::std::abs(fvel) * wheel_;
+      }
+      const double left_velocity = fvel - steering_velocity;
+      const double right_velocity = fvel + steering_velocity;
+      LOG(DEBUG, "l=%f r=%f\n", left_velocity, right_velocity);
+
+      // Integrate velocity to get the position.
+      // This position is used to get integral control.
+      loop_->mutable_R() << left_velocity, right_velocity;
+
+      if (!quickturn_) {
+        // K * R = w
+        Eigen::Matrix<double, 1, 2> equality_k;
+        equality_k << 1 + sign_svel, -(1 - sign_svel);
+        const double equality_w = 0.0;
+
+        // Construct a constraint on R by manipulating the constraint on U
+        ::aos::controls::HPolytope<2> R_poly = ::aos::controls::HPolytope<2>(
+            U_Poly_.H() * (loop_->K() + FF),
+            U_Poly_.k() + U_Poly_.H() * loop_->K() * loop_->X_hat());
+
+        // Limit R back inside the box.
+        loop_->mutable_R() =
+            CoerceGoal(R_poly, equality_k, equality_w, loop_->R());
+      }
+
+      const Eigen::Matrix<double, 2, 1> FF_volts = FF * loop_->R();
+      const Eigen::Matrix<double, 2, 1> U_ideal =
+          loop_->K() * (loop_->R() - loop_->X_hat()) + FF_volts;
+
+      for (int i = 0; i < 2; i++) {
+        loop_->mutable_U()[i] = ::aos::Clip(U_ideal[i], -12, 12);
+      }
+
+      // TODO(austin): Model this better.
+      // TODO(austin): Feed back?
+      loop_->mutable_X_hat() =
+          loop_->A() * loop_->X_hat() + loop_->B() * loop_->U();
+#if HAVE_SHIFTERS
+    } else {
+      // Any motor is not in gear.  Speed match.
+      ::Eigen::Matrix<double, 1, 1> R_left;
+      ::Eigen::Matrix<double, 1, 1> R_right;
+      R_left(0, 0) = left_motor_speed;
+      R_right(0, 0) = right_motor_speed;
+
+      const double wiggle =
+          (static_cast<double>((counter_ % 20) / 10) - 0.5) * 5.0;
+
+      loop_->mutable_U(0, 0) = ::aos::Clip(
+          (R_left / Kv)(0, 0) + (IsInGear(left_gear_) ? 0 : wiggle),
+          -12.0, 12.0);
+      loop_->mutable_U(1, 0) = ::aos::Clip(
+          (R_right / Kv)(0, 0) + (IsInGear(right_gear_) ? 0 : wiggle),
+          -12.0, 12.0);
+      loop_->mutable_U() *= 12.0 / ::aos::robot_state->voltage_battery;
+#endif
+    }
+  }
+
+  void SendMotors(DrivetrainQueue::Output *output) {
+    if (output != NULL) {
+      output->left_voltage = loop_->U(0, 0);
+      output->right_voltage = loop_->U(1, 0);
+      output->left_high = left_gear_ == HIGH || left_gear_ == SHIFTING_UP;
+      output->right_high = right_gear_ == HIGH || right_gear_ == SHIFTING_UP;
+    }
+  }
+
+ private:
+  const ::aos::controls::HPolytope<2> U_Poly_;
+
+  ::std::unique_ptr<StateFeedbackLoop<2, 2, 2>> loop_;
+
+  const double ttrust_;
+  double wheel_;
+  double throttle_;
+  bool quickturn_;
+  int stale_count_;
+  double position_time_delta_;
+  Gear left_gear_;
+  Gear right_gear_;
+  DrivetrainQueue::Position last_position_;
+  DrivetrainQueue::Position position_;
+  int counter_;
+};
+constexpr double PolyDrivetrain::kStallTorque;
+constexpr double PolyDrivetrain::kStallCurrent;
+constexpr double PolyDrivetrain::kFreeSpeed;
+constexpr double PolyDrivetrain::kFreeCurrent;
+constexpr double PolyDrivetrain::J;
+constexpr double PolyDrivetrain::m;
+constexpr double PolyDrivetrain::rb;
+constexpr double PolyDrivetrain::kWheelRadius;
+constexpr double PolyDrivetrain::kR;
+constexpr double PolyDrivetrain::Kv;
+constexpr double PolyDrivetrain::Kt;
+
+
+void DrivetrainLoop::RunIteration(const DrivetrainQueue::Goal *goal,
+                                  const DrivetrainQueue::Position *position,
+                                  DrivetrainQueue::Output *output,
+                                  DrivetrainQueue::Status * status) {
+  // TODO(aschuh): These should be members of the class.
+  static DrivetrainMotorsSS dt_closedloop;
+  static PolyDrivetrain dt_openloop;
+
+  bool bad_pos = false;
+  if (position == nullptr) {
+    LOG_INTERVAL(no_position_);
+    bad_pos = true;
+  }
+  no_position_.Print();
+
+  bool control_loop_driving = false;
+  if (goal) {
+    double wheel = goal->steering;
+    double throttle = goal->throttle;
+    bool quickturn = goal->quickturn;
+#if HAVE_SHIFTERS
+    bool highgear = goal->highgear;
+#endif
+
+    control_loop_driving = goal->control_loop_driving;
+    double left_goal = goal->left_goal;
+    double right_goal = goal->right_goal;
+
+    dt_closedloop.SetGoal(left_goal, goal->left_velocity_goal, right_goal,
+                          goal->right_velocity_goal);
+#if HAVE_SHIFTERS
+    dt_openloop.SetGoal(wheel, throttle, quickturn, highgear);
+#else
+    dt_openloop.SetGoal(wheel, throttle, quickturn, false);
+#endif
+  }
+
+  if (!bad_pos) {
+    const double left_encoder = position->left_encoder;
+    const double right_encoder = position->right_encoder;
+    if (gyro_reading.FetchLatest()) {
+      LOG_STRUCT(DEBUG, "using", *gyro_reading.get());
+      dt_closedloop.SetPosition(left_encoder, right_encoder,
+                                gyro_reading->angle);
+    } else {
+      dt_closedloop.SetRawPosition(left_encoder, right_encoder);
+    }
+  }
+  dt_openloop.SetPosition(position);
+  dt_openloop.Update();
+
+  if (control_loop_driving) {
+    dt_closedloop.Update(output == NULL, true);
+    dt_closedloop.SendMotors(output);
+  } else {
+    dt_openloop.SendMotors(output);
+    if (output) {
+      dt_closedloop.SetExternalMotors(output->left_voltage,
+                                      output->right_voltage);
+    }
+    dt_closedloop.Update(output == NULL, false);
+  }
+
+  // set the output status of the control loop state
+  if (status) {
+    bool done = false;
+    if (goal) {
+      done = ((::std::abs(goal->left_goal -
+                          dt_closedloop.GetEstimatedLeftEncoder()) <
+               constants::GetValues().drivetrain_done_distance) &&
+              (::std::abs(goal->right_goal -
+                          dt_closedloop.GetEstimatedRightEncoder()) <
+               constants::GetValues().drivetrain_done_distance));
+    }
+    status->is_done = done;
+    status->robot_speed = dt_closedloop.GetEstimatedRobotSpeed();
+    status->filtered_left_position = dt_closedloop.GetEstimatedLeftEncoder();
+    status->filtered_right_position = dt_closedloop.GetEstimatedRightEncoder();
+
+    status->filtered_left_velocity = dt_closedloop.loop().X_hat(1, 0);
+    status->filtered_right_velocity = dt_closedloop.loop().X_hat(3, 0);
+    status->output_was_capped = dt_closedloop.OutputWasCapped();
+    status->uncapped_left_voltage = dt_closedloop.loop().U_uncapped(0, 0);
+    status->uncapped_right_voltage = dt_closedloop.loop().U_uncapped(1, 0);
+  }
+}
+
+}  // namespace control_loops
+}  // namespace frc971
diff --git a/y2015/control_loops/drivetrain/drivetrain.gyp b/y2015/control_loops/drivetrain/drivetrain.gyp
new file mode 100644
index 0000000..4333258
--- /dev/null
+++ b/y2015/control_loops/drivetrain/drivetrain.gyp
@@ -0,0 +1,103 @@
+{
+  'targets': [
+    {
+      'target_name': 'replay_drivetrain',
+      'type': 'executable',
+      'variables': {
+        'no_rsync': 1,
+      },
+      'sources': [
+        'replay_drivetrain.cc',
+      ],
+      'dependencies': [
+        'drivetrain_queue',
+        '<(AOS)/common/controls/controls.gyp:replay_control_loop',
+        '<(AOS)/linux_code/linux_code.gyp:init',
+      ],
+    },
+    {
+      'target_name': 'drivetrain_queue',
+      'type': 'static_library',
+      'sources': ['drivetrain.q'],
+      'variables': {
+        'header_path': 'y2015/control_loops/drivetrain',
+      },
+      'dependencies': [
+        '<(AOS)/common/controls/controls.gyp:control_loop_queues',
+      ],
+      'export_dependent_settings': [
+        '<(AOS)/common/controls/controls.gyp:control_loop_queues',
+      ],
+      'includes': ['../../../aos/build/queues.gypi'],
+    },
+    {
+      'target_name': 'polydrivetrain_plants',
+      'type': 'static_library',
+      'sources': [
+        'polydrivetrain_dog_motor_plant.cc',
+        'drivetrain_dog_motor_plant.cc',
+      ],
+      'dependencies': [
+        '<(DEPTH)/frc971/control_loops/control_loops.gyp:state_feedback_loop',
+      ],
+      'export_dependent_settings': [
+        '<(DEPTH)/frc971/control_loops/control_loops.gyp:state_feedback_loop',
+      ],
+    },
+    {
+      'target_name': 'drivetrain_lib',
+      'type': 'static_library',
+      'sources': [
+        'drivetrain.cc',
+        'polydrivetrain_cim_plant.cc',
+      ],
+      'dependencies': [
+        'drivetrain_queue',
+        '<(AOS)/common/controls/controls.gyp:control_loop',
+        '<(DEPTH)/y2015/y2015.gyp:constants',
+        '<(AOS)/common/controls/controls.gyp:polytope',
+        '<(DEPTH)/frc971/control_loops/control_loops.gyp:state_feedback_loop',
+        '<(DEPTH)/frc971/control_loops/control_loops.gyp:coerce_goal',
+        '<(DEPTH)/frc971/queues/queues.gyp:gyro',
+        '<(AOS)/common/util/util.gyp:log_interval',
+        '<(AOS)/common/logging/logging.gyp:queue_logging',
+        '<(AOS)/common/logging/logging.gyp:matrix_logging',
+      ],
+      'export_dependent_settings': [
+        '<(AOS)/common/controls/controls.gyp:polytope',
+        '<(DEPTH)/frc971/control_loops/control_loops.gyp:state_feedback_loop',
+        '<(DEPTH)/frc971/control_loops/control_loops.gyp:coerce_goal',
+        '<(AOS)/common/controls/controls.gyp:control_loop',
+        'drivetrain_queue',
+      ],
+    },
+    {
+      'target_name': 'drivetrain_lib_test',
+      'type': 'executable',
+      'sources': [
+        'drivetrain_lib_test.cc',
+      ],
+      'dependencies': [
+        '<(EXTERNALS):gtest',
+        'drivetrain_queue',
+        'drivetrain_lib',
+        '<(AOS)/common/controls/controls.gyp:control_loop_test',
+        '<(DEPTH)/frc971/control_loops/control_loops.gyp:state_feedback_loop',
+        '<(DEPTH)/frc971/queues/queues.gyp:gyro',
+        '<(AOS)/common/common.gyp:queues',
+      ],
+    },
+    {
+      'target_name': 'drivetrain',
+      'type': 'executable',
+      'sources': [
+        'drivetrain_main.cc',
+      ],
+      'dependencies': [
+        '<(AOS)/linux_code/linux_code.gyp:init',
+        'drivetrain_lib',
+        'drivetrain_queue',
+      ],
+    },
+  ],
+}
diff --git a/y2015/control_loops/drivetrain/drivetrain.h b/y2015/control_loops/drivetrain/drivetrain.h
new file mode 100644
index 0000000..8e8768e
--- /dev/null
+++ b/y2015/control_loops/drivetrain/drivetrain.h
@@ -0,0 +1,43 @@
+#ifndef Y2015_CONTROL_LOOPS_DRIVETRAIN_H_
+#define Y2015_CONTROL_LOOPS_DRIVETRAIN_H_
+
+#include "Eigen/Dense"
+
+#include "aos/common/controls/polytope.h"
+#include "aos/common/controls/control_loop.h"
+#include "aos/common/controls/polytope.h"
+#include "y2015/control_loops/drivetrain/drivetrain.q.h"
+#include "aos/common/util/log_interval.h"
+
+namespace frc971 {
+namespace control_loops {
+
+class DrivetrainLoop
+    : public aos::controls::ControlLoop<control_loops::DrivetrainQueue> {
+ public:
+  // Constructs a control loop which can take a Drivetrain or defaults to the
+  // drivetrain at frc971::control_loops::drivetrain
+  explicit DrivetrainLoop(control_loops::DrivetrainQueue *my_drivetrain =
+                              &control_loops::drivetrain_queue)
+      : aos::controls::ControlLoop<control_loops::DrivetrainQueue>(
+            my_drivetrain) {
+    ::aos::controls::HPolytope<0>::Init();
+  }
+
+ protected:
+  // Executes one cycle of the control loop.
+  virtual void RunIteration(
+      const control_loops::DrivetrainQueue::Goal *goal,
+      const control_loops::DrivetrainQueue::Position *position,
+      control_loops::DrivetrainQueue::Output *output,
+      control_loops::DrivetrainQueue::Status *status);
+
+  typedef ::aos::util::SimpleLogInterval SimpleLogInterval;
+  SimpleLogInterval no_position_ = SimpleLogInterval(
+      ::aos::time::Time::InSeconds(0.25), WARNING, "no position");
+};
+
+}  // namespace control_loops
+}  // namespace frc971
+
+#endif  // Y2015_CONTROL_LOOPS_DRIVETRAIN_H_
diff --git a/y2015/control_loops/drivetrain/drivetrain.q b/y2015/control_loops/drivetrain/drivetrain.q
new file mode 100644
index 0000000..942c5b3
--- /dev/null
+++ b/y2015/control_loops/drivetrain/drivetrain.q
@@ -0,0 +1,71 @@
+package frc971.control_loops;
+
+import "aos/common/controls/control_loops.q";
+
+struct GearLogging {
+  int8_t controller_index;
+  bool left_loop_high;
+  bool right_loop_high;
+  int8_t left_state;
+  int8_t right_state;
+};
+
+struct CIMLogging {
+  bool left_in_gear;
+  bool right_in_gear;
+  double left_motor_speed;
+  double right_motor_speed;
+  double left_velocity;
+  double right_velocity;
+};
+
+queue_group DrivetrainQueue {
+  implements aos.control_loops.ControlLoop;
+
+  message Goal {
+    double steering;
+    double throttle;
+    //bool highgear;
+    bool quickturn;
+    bool control_loop_driving;
+    double left_goal;
+    double left_velocity_goal;
+    double right_goal;
+    double right_velocity_goal;
+  };
+
+  message Position {
+    double left_encoder;
+    double right_encoder;
+    //double left_shifter_position;
+    //double right_shifter_position;
+  };
+
+  message Output {
+    double left_voltage;
+    double right_voltage;
+    bool left_high;
+    bool right_high;
+  };
+
+  message Status {
+    double robot_speed;
+    double filtered_left_position;
+    double filtered_right_position;
+    double filtered_left_velocity;
+    double filtered_right_velocity;
+
+    double uncapped_left_voltage;
+    double uncapped_right_voltage;
+    bool output_was_capped;
+
+    bool is_done;
+  };
+
+  queue Goal goal;
+  queue Position position;
+  queue Output output;
+  queue Status status;
+};
+
+queue_group DrivetrainQueue drivetrain_queue;
diff --git a/y2015/control_loops/drivetrain/drivetrain_dog_motor_plant.cc b/y2015/control_loops/drivetrain/drivetrain_dog_motor_plant.cc
new file mode 100644
index 0000000..e2f5a9a
--- /dev/null
+++ b/y2015/control_loops/drivetrain/drivetrain_dog_motor_plant.cc
@@ -0,0 +1,133 @@
+#include "y2015/control_loops/drivetrain/drivetrain_dog_motor_plant.h"
+
+#include <vector>
+
+#include "frc971/control_loops/state_feedback_loop.h"
+
+namespace frc971 {
+namespace control_loops {
+
+StateFeedbackPlantCoefficients<4, 2, 2> MakeDrivetrainLowLowPlantCoefficients() {
+  Eigen::Matrix<double, 4, 4> A;
+  A << 1.0, 0.00494348612824, 0.0, 1.24048455404e-05, 0.0, 0.977484092703, 0.0, 0.00492433284048, 0.0, 1.24048455404e-05, 1.0, 0.00494348612824, 0.0, 0.00492433284048, 0.0, 0.977484092703;
+  Eigen::Matrix<double, 4, 2> B;
+  B << 2.09180756177e-05, -4.59153636043e-06, 0.00833405032795, -0.00182269526971, -4.59153636043e-06, 2.09180756177e-05, -0.00182269526971, 0.00833405032795;
+  Eigen::Matrix<double, 2, 4> C;
+  C << 1, 0, 0, 0, 0, 0, 1, 0;
+  Eigen::Matrix<double, 2, 2> D;
+  D << 0, 0, 0, 0;
+  Eigen::Matrix<double, 2, 1> U_max;
+  U_max << 12.0, 12.0;
+  Eigen::Matrix<double, 2, 1> U_min;
+  U_min << -12.0, -12.0;
+  return StateFeedbackPlantCoefficients<4, 2, 2>(A, B, C, D, U_max, U_min);
+}
+
+StateFeedbackPlantCoefficients<4, 2, 2> MakeDrivetrainLowHighPlantCoefficients() {
+  Eigen::Matrix<double, 4, 4> A;
+  A << 1.0, 0.00494348612824, 0.0, 1.24048455404e-05, 0.0, 0.977484092703, 0.0, 0.00492433284048, 0.0, 1.24048455404e-05, 1.0, 0.00494348612824, 0.0, 0.00492433284048, 0.0, 0.977484092703;
+  Eigen::Matrix<double, 4, 2> B;
+  B << 2.09180756177e-05, -4.59153636043e-06, 0.00833405032795, -0.00182269526971, -4.59153636043e-06, 2.09180756177e-05, -0.00182269526971, 0.00833405032795;
+  Eigen::Matrix<double, 2, 4> C;
+  C << 1, 0, 0, 0, 0, 0, 1, 0;
+  Eigen::Matrix<double, 2, 2> D;
+  D << 0, 0, 0, 0;
+  Eigen::Matrix<double, 2, 1> U_max;
+  U_max << 12.0, 12.0;
+  Eigen::Matrix<double, 2, 1> U_min;
+  U_min << -12.0, -12.0;
+  return StateFeedbackPlantCoefficients<4, 2, 2>(A, B, C, D, U_max, U_min);
+}
+
+StateFeedbackPlantCoefficients<4, 2, 2> MakeDrivetrainHighLowPlantCoefficients() {
+  Eigen::Matrix<double, 4, 4> A;
+  A << 1.0, 0.00494348612824, 0.0, 1.24048455404e-05, 0.0, 0.977484092703, 0.0, 0.00492433284048, 0.0, 1.24048455404e-05, 1.0, 0.00494348612824, 0.0, 0.00492433284048, 0.0, 0.977484092703;
+  Eigen::Matrix<double, 4, 2> B;
+  B << 2.09180756177e-05, -4.59153636043e-06, 0.00833405032795, -0.00182269526971, -4.59153636043e-06, 2.09180756177e-05, -0.00182269526971, 0.00833405032795;
+  Eigen::Matrix<double, 2, 4> C;
+  C << 1, 0, 0, 0, 0, 0, 1, 0;
+  Eigen::Matrix<double, 2, 2> D;
+  D << 0, 0, 0, 0;
+  Eigen::Matrix<double, 2, 1> U_max;
+  U_max << 12.0, 12.0;
+  Eigen::Matrix<double, 2, 1> U_min;
+  U_min << -12.0, -12.0;
+  return StateFeedbackPlantCoefficients<4, 2, 2>(A, B, C, D, U_max, U_min);
+}
+
+StateFeedbackPlantCoefficients<4, 2, 2> MakeDrivetrainHighHighPlantCoefficients() {
+  Eigen::Matrix<double, 4, 4> A;
+  A << 1.0, 0.00494348612824, 0.0, 1.24048455404e-05, 0.0, 0.977484092703, 0.0, 0.00492433284048, 0.0, 1.24048455404e-05, 1.0, 0.00494348612824, 0.0, 0.00492433284048, 0.0, 0.977484092703;
+  Eigen::Matrix<double, 4, 2> B;
+  B << 2.09180756177e-05, -4.59153636043e-06, 0.00833405032795, -0.00182269526971, -4.59153636043e-06, 2.09180756177e-05, -0.00182269526971, 0.00833405032795;
+  Eigen::Matrix<double, 2, 4> C;
+  C << 1, 0, 0, 0, 0, 0, 1, 0;
+  Eigen::Matrix<double, 2, 2> D;
+  D << 0, 0, 0, 0;
+  Eigen::Matrix<double, 2, 1> U_max;
+  U_max << 12.0, 12.0;
+  Eigen::Matrix<double, 2, 1> U_min;
+  U_min << -12.0, -12.0;
+  return StateFeedbackPlantCoefficients<4, 2, 2>(A, B, C, D, U_max, U_min);
+}
+
+StateFeedbackController<4, 2, 2> MakeDrivetrainLowLowController() {
+  Eigen::Matrix<double, 4, 2> L;
+  L << 1.2774840927, 0.00492433284048, 79.1440456622, 1.05150722636, 0.00492433284048, 1.2774840927, 1.05150722636, 79.1440456622;
+  Eigen::Matrix<double, 2, 4> K;
+  K << 160.19677247, 15.5358468938, 1.60401194139, 1.33861213093, 1.60401194142, 1.33861213094, 160.19677247, 15.5358468938;
+  Eigen::Matrix<double, 4, 4> A_inv;
+  A_inv << 1.0, -0.00505742153256, 0.0, 1.27875036472e-05, 0.0, 1.02306051542, 0.0, -0.00515393603998, 0.0, 1.27875036472e-05, 1.0, -0.00505742153256, 0.0, -0.00515393603998, 0.0, 1.02306051542;
+  return StateFeedbackController<4, 2, 2>(L, K, A_inv, MakeDrivetrainLowLowPlantCoefficients());
+}
+
+StateFeedbackController<4, 2, 2> MakeDrivetrainLowHighController() {
+  Eigen::Matrix<double, 4, 2> L;
+  L << 1.2774840927, 0.00492433284048, 79.1440456622, 1.05150722636, 0.00492433284048, 1.2774840927, 1.05150722636, 79.1440456622;
+  Eigen::Matrix<double, 2, 4> K;
+  K << 160.19677247, 15.5358468938, 1.60401194139, 1.33861213093, 1.60401194142, 1.33861213094, 160.19677247, 15.5358468938;
+  Eigen::Matrix<double, 4, 4> A_inv;
+  A_inv << 1.0, -0.00505742153256, 0.0, 1.27875036472e-05, 0.0, 1.02306051542, 0.0, -0.00515393603998, 0.0, 1.27875036472e-05, 1.0, -0.00505742153256, 0.0, -0.00515393603998, 0.0, 1.02306051542;
+  return StateFeedbackController<4, 2, 2>(L, K, A_inv, MakeDrivetrainLowHighPlantCoefficients());
+}
+
+StateFeedbackController<4, 2, 2> MakeDrivetrainHighLowController() {
+  Eigen::Matrix<double, 4, 2> L;
+  L << 1.2774840927, 0.00492433284048, 79.1440456622, 1.05150722636, 0.00492433284048, 1.2774840927, 1.05150722636, 79.1440456622;
+  Eigen::Matrix<double, 2, 4> K;
+  K << 160.19677247, 15.5358468938, 1.60401194139, 1.33861213093, 1.60401194142, 1.33861213094, 160.19677247, 15.5358468938;
+  Eigen::Matrix<double, 4, 4> A_inv;
+  A_inv << 1.0, -0.00505742153256, 0.0, 1.27875036472e-05, 0.0, 1.02306051542, 0.0, -0.00515393603998, 0.0, 1.27875036472e-05, 1.0, -0.00505742153256, 0.0, -0.00515393603998, 0.0, 1.02306051542;
+  return StateFeedbackController<4, 2, 2>(L, K, A_inv, MakeDrivetrainHighLowPlantCoefficients());
+}
+
+StateFeedbackController<4, 2, 2> MakeDrivetrainHighHighController() {
+  Eigen::Matrix<double, 4, 2> L;
+  L << 1.2774840927, 0.00492433284048, 79.1440456622, 1.05150722636, 0.00492433284048, 1.2774840927, 1.05150722636, 79.1440456622;
+  Eigen::Matrix<double, 2, 4> K;
+  K << 160.19677247, 15.5358468938, 1.60401194139, 1.33861213093, 1.60401194142, 1.33861213094, 160.19677247, 15.5358468938;
+  Eigen::Matrix<double, 4, 4> A_inv;
+  A_inv << 1.0, -0.00505742153256, 0.0, 1.27875036472e-05, 0.0, 1.02306051542, 0.0, -0.00515393603998, 0.0, 1.27875036472e-05, 1.0, -0.00505742153256, 0.0, -0.00515393603998, 0.0, 1.02306051542;
+  return StateFeedbackController<4, 2, 2>(L, K, A_inv, MakeDrivetrainHighHighPlantCoefficients());
+}
+
+StateFeedbackPlant<4, 2, 2> MakeDrivetrainPlant() {
+  ::std::vector< ::std::unique_ptr<StateFeedbackPlantCoefficients<4, 2, 2>>> plants(4);
+  plants[0] = ::std::unique_ptr<StateFeedbackPlantCoefficients<4, 2, 2>>(new StateFeedbackPlantCoefficients<4, 2, 2>(MakeDrivetrainLowLowPlantCoefficients()));
+  plants[1] = ::std::unique_ptr<StateFeedbackPlantCoefficients<4, 2, 2>>(new StateFeedbackPlantCoefficients<4, 2, 2>(MakeDrivetrainLowHighPlantCoefficients()));
+  plants[2] = ::std::unique_ptr<StateFeedbackPlantCoefficients<4, 2, 2>>(new StateFeedbackPlantCoefficients<4, 2, 2>(MakeDrivetrainHighLowPlantCoefficients()));
+  plants[3] = ::std::unique_ptr<StateFeedbackPlantCoefficients<4, 2, 2>>(new StateFeedbackPlantCoefficients<4, 2, 2>(MakeDrivetrainHighHighPlantCoefficients()));
+  return StateFeedbackPlant<4, 2, 2>(&plants);
+}
+
+StateFeedbackLoop<4, 2, 2> MakeDrivetrainLoop() {
+  ::std::vector< ::std::unique_ptr<StateFeedbackController<4, 2, 2>>> controllers(4);
+  controllers[0] = ::std::unique_ptr<StateFeedbackController<4, 2, 2>>(new StateFeedbackController<4, 2, 2>(MakeDrivetrainLowLowController()));
+  controllers[1] = ::std::unique_ptr<StateFeedbackController<4, 2, 2>>(new StateFeedbackController<4, 2, 2>(MakeDrivetrainLowHighController()));
+  controllers[2] = ::std::unique_ptr<StateFeedbackController<4, 2, 2>>(new StateFeedbackController<4, 2, 2>(MakeDrivetrainHighLowController()));
+  controllers[3] = ::std::unique_ptr<StateFeedbackController<4, 2, 2>>(new StateFeedbackController<4, 2, 2>(MakeDrivetrainHighHighController()));
+  return StateFeedbackLoop<4, 2, 2>(&controllers);
+}
+
+}  // namespace control_loops
+}  // namespace frc971
diff --git a/y2015/control_loops/drivetrain/drivetrain_dog_motor_plant.h b/y2015/control_loops/drivetrain/drivetrain_dog_motor_plant.h
new file mode 100644
index 0000000..a2848be
--- /dev/null
+++ b/y2015/control_loops/drivetrain/drivetrain_dog_motor_plant.h
@@ -0,0 +1,32 @@
+#ifndef Y2015_CONTROL_LOOPS_DRIVETRAIN_DRIVETRAIN_DOG_MOTOR_PLANT_H_
+#define Y2015_CONTROL_LOOPS_DRIVETRAIN_DRIVETRAIN_DOG_MOTOR_PLANT_H_
+
+#include "frc971/control_loops/state_feedback_loop.h"
+
+namespace frc971 {
+namespace control_loops {
+
+StateFeedbackPlantCoefficients<4, 2, 2> MakeDrivetrainLowLowPlantCoefficients();
+
+StateFeedbackController<4, 2, 2> MakeDrivetrainLowLowController();
+
+StateFeedbackPlantCoefficients<4, 2, 2> MakeDrivetrainLowHighPlantCoefficients();
+
+StateFeedbackController<4, 2, 2> MakeDrivetrainLowHighController();
+
+StateFeedbackPlantCoefficients<4, 2, 2> MakeDrivetrainHighLowPlantCoefficients();
+
+StateFeedbackController<4, 2, 2> MakeDrivetrainHighLowController();
+
+StateFeedbackPlantCoefficients<4, 2, 2> MakeDrivetrainHighHighPlantCoefficients();
+
+StateFeedbackController<4, 2, 2> MakeDrivetrainHighHighController();
+
+StateFeedbackPlant<4, 2, 2> MakeDrivetrainPlant();
+
+StateFeedbackLoop<4, 2, 2> MakeDrivetrainLoop();
+
+}  // namespace control_loops
+}  // namespace frc971
+
+#endif  // Y2015_CONTROL_LOOPS_DRIVETRAIN_DRIVETRAIN_DOG_MOTOR_PLANT_H_
diff --git a/y2015/control_loops/drivetrain/drivetrain_lib_test.cc b/y2015/control_loops/drivetrain/drivetrain_lib_test.cc
new file mode 100644
index 0000000..d3869aa
--- /dev/null
+++ b/y2015/control_loops/drivetrain/drivetrain_lib_test.cc
@@ -0,0 +1,297 @@
+#include <unistd.h>
+
+#include <memory>
+
+#include "gtest/gtest.h"
+#include "aos/common/network/team_number.h"
+#include "aos/common/queue_testutils.h"
+#include "aos/common/controls/polytope.h"
+#include "aos/common/controls/control_loop_test.h"
+
+#include "y2015/control_loops/drivetrain/drivetrain.q.h"
+#include "y2015/control_loops/drivetrain/drivetrain.h"
+#include "frc971/control_loops/state_feedback_loop.h"
+#include "frc971/control_loops/coerce_goal.h"
+#include "y2015/control_loops/drivetrain/drivetrain_dog_motor_plant.h"
+#include "frc971/queues/gyro.q.h"
+
+
+namespace frc971 {
+namespace control_loops {
+namespace testing {
+
+class Environment : public ::testing::Environment {
+ public:
+  virtual ~Environment() {}
+  // how to set up the environment.
+  virtual void SetUp() {
+    aos::controls::HPolytope<0>::Init();
+  }
+};
+::testing::Environment* const holder_env =
+  ::testing::AddGlobalTestEnvironment(new Environment);
+
+class TeamNumberEnvironment : public ::testing::Environment {
+ public:
+  // Override this to define how to set up the environment.
+  virtual void SetUp() { aos::network::OverrideTeamNumber(971); }
+};
+
+::testing::Environment* const team_number_env =
+    ::testing::AddGlobalTestEnvironment(new TeamNumberEnvironment);
+
+// Class which simulates the drivetrain and sends out queue messages containing
+// the position.
+class DrivetrainSimulation {
+ public:
+  // Constructs a motor simulation.
+  // TODO(aschuh) Do we want to test the clutch one too?
+  DrivetrainSimulation()
+      : drivetrain_plant_(
+            new StateFeedbackPlant<4, 2, 2>(MakeDrivetrainPlant())),
+        my_drivetrain_queue_(".frc971.control_loops.drivetrain",
+                       0x8a8dde77, ".frc971.control_loops.drivetrain.goal",
+                       ".frc971.control_loops.drivetrain.position",
+                       ".frc971.control_loops.drivetrain.output",
+                       ".frc971.control_loops.drivetrain.status") {
+    Reinitialize();
+  }
+
+  // Resets the plant.
+  void Reinitialize() {
+    drivetrain_plant_->mutable_X(0, 0) = 0.0;
+    drivetrain_plant_->mutable_X(1, 0) = 0.0;
+    drivetrain_plant_->mutable_Y() =
+        drivetrain_plant_->C() * drivetrain_plant_->X();
+    last_left_position_ = drivetrain_plant_->Y(0, 0);
+    last_right_position_ = drivetrain_plant_->Y(1, 0);
+  }
+
+  // Returns the position of the drivetrain.
+  double GetLeftPosition() const { return drivetrain_plant_->Y(0, 0); }
+  double GetRightPosition() const { return drivetrain_plant_->Y(1, 0); }
+
+  // Sends out the position queue messages.
+  void SendPositionMessage() {
+    const double left_encoder = GetLeftPosition();
+    const double right_encoder = GetRightPosition();
+
+    ::aos::ScopedMessagePtr<control_loops::DrivetrainQueue::Position> position =
+        my_drivetrain_queue_.position.MakeMessage();
+    position->left_encoder = left_encoder;
+    position->right_encoder = right_encoder;
+    position.Send();
+  }
+
+  // Simulates the drivetrain moving for one timestep.
+  void Simulate() {
+    last_left_position_ = drivetrain_plant_->Y(0, 0);
+    last_right_position_ = drivetrain_plant_->Y(1, 0);
+    EXPECT_TRUE(my_drivetrain_queue_.output.FetchLatest());
+    drivetrain_plant_->mutable_U() << my_drivetrain_queue_.output->left_voltage,
+        my_drivetrain_queue_.output->right_voltage;
+    drivetrain_plant_->Update();
+  }
+
+  ::std::unique_ptr<StateFeedbackPlant<4, 2, 2>> drivetrain_plant_;
+ private:
+  DrivetrainQueue my_drivetrain_queue_;
+  double last_left_position_;
+  double last_right_position_;
+};
+
+class DrivetrainTest : public ::aos::testing::ControlLoopTest {
+ protected:
+  // Create a new instance of the test queue so that it invalidates the queue
+  // that it points to.  Otherwise, we will have a pointer to shared memory that
+  // is no longer valid.
+  DrivetrainQueue my_drivetrain_queue_;
+
+  // Create a loop and simulation plant.
+  DrivetrainLoop drivetrain_motor_;
+  DrivetrainSimulation drivetrain_motor_plant_;
+
+  DrivetrainTest() : my_drivetrain_queue_(".frc971.control_loops.drivetrain",
+                               0x8a8dde77,
+                               ".frc971.control_loops.drivetrain.goal",
+                               ".frc971.control_loops.drivetrain.position",
+                               ".frc971.control_loops.drivetrain.output",
+                               ".frc971.control_loops.drivetrain.status"),
+                drivetrain_motor_(&my_drivetrain_queue_),
+                drivetrain_motor_plant_() {
+    ::frc971::sensors::gyro_reading.Clear();
+  }
+
+  void VerifyNearGoal() {
+    my_drivetrain_queue_.goal.FetchLatest();
+    my_drivetrain_queue_.position.FetchLatest();
+    EXPECT_NEAR(my_drivetrain_queue_.goal->left_goal,
+                drivetrain_motor_plant_.GetLeftPosition(),
+                1e-2);
+    EXPECT_NEAR(my_drivetrain_queue_.goal->right_goal,
+                drivetrain_motor_plant_.GetRightPosition(),
+                1e-2);
+  }
+
+  virtual ~DrivetrainTest() {
+    ::frc971::sensors::gyro_reading.Clear();
+  }
+};
+
+// Tests that the drivetrain converges on a goal.
+TEST_F(DrivetrainTest, ConvergesCorrectly) {
+  my_drivetrain_queue_.goal.MakeWithBuilder().control_loop_driving(true)
+      .left_goal(-1.0)
+      .right_goal(1.0).Send();
+  for (int i = 0; i < 200; ++i) {
+    drivetrain_motor_plant_.SendPositionMessage();
+    drivetrain_motor_.Iterate();
+    drivetrain_motor_plant_.Simulate();
+    SimulateTimestep(true);
+  }
+  VerifyNearGoal();
+}
+
+// Tests that it survives disabling.
+TEST_F(DrivetrainTest, SurvivesDisabling) {
+  my_drivetrain_queue_.goal.MakeWithBuilder().control_loop_driving(true)
+      .left_goal(-1.0)
+      .right_goal(1.0).Send();
+  for (int i = 0; i < 500; ++i) {
+    drivetrain_motor_plant_.SendPositionMessage();
+    drivetrain_motor_.Iterate();
+    drivetrain_motor_plant_.Simulate();
+    if (i > 20 && i < 200) {
+      SimulateTimestep(false);
+    } else {
+      SimulateTimestep(true);
+    }
+  }
+  VerifyNearGoal();
+}
+
+// Tests that never having a goal doesn't break.
+TEST_F(DrivetrainTest, NoGoalStart) {
+  for (int i = 0; i < 20; ++i) {
+    drivetrain_motor_plant_.SendPositionMessage();
+    drivetrain_motor_.Iterate();
+    drivetrain_motor_plant_.Simulate();
+  }
+}
+
+// Tests that never having a goal, but having driver's station messages, doesn't
+// break.
+TEST_F(DrivetrainTest, NoGoalWithRobotState) {
+  for (int i = 0; i < 20; ++i) {
+    drivetrain_motor_plant_.SendPositionMessage();
+    drivetrain_motor_.Iterate();
+    drivetrain_motor_plant_.Simulate();
+    SimulateTimestep(true);
+  }
+}
+
+::aos::controls::HPolytope<2> MakeBox(double x1_min, double x1_max,
+                                      double x2_min, double x2_max) {
+  Eigen::Matrix<double, 4, 2> box_H;
+  box_H << /*[[*/ 1.0, 0.0 /*]*/,
+            /*[*/-1.0, 0.0 /*]*/,
+            /*[*/ 0.0, 1.0 /*]*/,
+            /*[*/ 0.0,-1.0 /*]]*/;
+  Eigen::Matrix<double, 4, 1> box_k;
+  box_k << /*[[*/ x1_max /*]*/,
+            /*[*/-x1_min /*]*/,
+            /*[*/ x2_max /*]*/,
+            /*[*/-x2_min /*]]*/;
+  ::aos::controls::HPolytope<2> t_poly(box_H, box_k);
+  return t_poly;
+}
+
+class CoerceGoalTest : public ::testing::Test {
+ public:
+  EIGEN_MAKE_ALIGNED_OPERATOR_NEW
+};
+
+// WHOOOHH!
+TEST_F(CoerceGoalTest, Inside) {
+  ::aos::controls::HPolytope<2> box = MakeBox(1, 2, 1, 2);
+
+  Eigen::Matrix<double, 1, 2> K;
+  K << /*[[*/ 1, -1 /*]]*/;
+
+  Eigen::Matrix<double, 2, 1> R;
+  R << /*[[*/ 1.5, 1.5 /*]]*/;
+
+  Eigen::Matrix<double, 2, 1> output =
+      ::frc971::control_loops::CoerceGoal(box, K, 0, R);
+
+  EXPECT_EQ(R(0, 0), output(0, 0));
+  EXPECT_EQ(R(1, 0), output(1, 0));
+}
+
+TEST_F(CoerceGoalTest, Outside_Inside_Intersect) {
+  ::aos::controls::HPolytope<2> box = MakeBox(1, 2, 1, 2);
+
+  Eigen::Matrix<double, 1, 2> K;
+  K << 1, -1;
+
+  Eigen::Matrix<double, 2, 1> R;
+  R << 5, 5;
+
+  Eigen::Matrix<double, 2, 1> output =
+      ::frc971::control_loops::CoerceGoal(box, K, 0, R);
+
+  EXPECT_EQ(2.0, output(0, 0));
+  EXPECT_EQ(2.0, output(1, 0));
+}
+
+TEST_F(CoerceGoalTest, Outside_Inside_no_Intersect) {
+  ::aos::controls::HPolytope<2> box = MakeBox(3, 4, 1, 2);
+
+  Eigen::Matrix<double, 1, 2> K;
+  K << 1, -1;
+
+  Eigen::Matrix<double, 2, 1> R;
+  R << 5, 5;
+
+  Eigen::Matrix<double, 2, 1> output =
+      ::frc971::control_loops::CoerceGoal(box, K, 0, R);
+
+  EXPECT_EQ(3.0, output(0, 0));
+  EXPECT_EQ(2.0, output(1, 0));
+}
+
+TEST_F(CoerceGoalTest, Middle_Of_Edge) {
+  ::aos::controls::HPolytope<2> box = MakeBox(0, 4, 1, 2);
+
+  Eigen::Matrix<double, 1, 2> K;
+  K << -1, 1;
+
+  Eigen::Matrix<double, 2, 1> R;
+  R << 5, 5;
+
+  Eigen::Matrix<double, 2, 1> output =
+      ::frc971::control_loops::CoerceGoal(box, K, 0, R);
+
+  EXPECT_EQ(2.0, output(0, 0));
+  EXPECT_EQ(2.0, output(1, 0));
+}
+
+TEST_F(CoerceGoalTest, PerpendicularLine) {
+  ::aos::controls::HPolytope<2> box = MakeBox(1, 2, 1, 2);
+
+  Eigen::Matrix<double, 1, 2> K;
+  K << 1, 1;
+
+  Eigen::Matrix<double, 2, 1> R;
+  R << 5, 5;
+
+  Eigen::Matrix<double, 2, 1> output =
+      ::frc971::control_loops::CoerceGoal(box, K, 0, R);
+
+  EXPECT_EQ(1.0, output(0, 0));
+  EXPECT_EQ(1.0, output(1, 0));
+}
+
+}  // namespace testing
+}  // namespace control_loops
+}  // namespace frc971
diff --git a/y2015/control_loops/drivetrain/drivetrain_main.cc b/y2015/control_loops/drivetrain/drivetrain_main.cc
new file mode 100644
index 0000000..10a50f3
--- /dev/null
+++ b/y2015/control_loops/drivetrain/drivetrain_main.cc
@@ -0,0 +1,11 @@
+#include "y2015/control_loops/drivetrain/drivetrain.h"
+
+#include "aos/linux_code/init.h"
+
+int main() {
+  ::aos::Init();
+  frc971::control_loops::DrivetrainLoop drivetrain;
+  drivetrain.Run();
+  ::aos::Cleanup();
+  return 0;
+}
diff --git a/y2015/control_loops/drivetrain/polydrivetrain_cim_plant.cc b/y2015/control_loops/drivetrain/polydrivetrain_cim_plant.cc
new file mode 100644
index 0000000..36ebb59
--- /dev/null
+++ b/y2015/control_loops/drivetrain/polydrivetrain_cim_plant.cc
@@ -0,0 +1,49 @@
+#include "y2015/control_loops/drivetrain/polydrivetrain_cim_plant.h"
+
+#include <vector>
+
+#include "frc971/control_loops/state_feedback_loop.h"
+
+namespace frc971 {
+namespace control_loops {
+
+StateFeedbackPlantCoefficients<1, 1, 1> MakeCIMPlantCoefficients() {
+  Eigen::Matrix<double, 1, 1> A;
+  A << 0.783924473544;
+  Eigen::Matrix<double, 1, 1> B;
+  B << 8.94979586973;
+  Eigen::Matrix<double, 1, 1> C;
+  C << 1;
+  Eigen::Matrix<double, 1, 1> D;
+  D << 0;
+  Eigen::Matrix<double, 1, 1> U_max;
+  U_max << 12.0;
+  Eigen::Matrix<double, 1, 1> U_min;
+  U_min << -12.0;
+  return StateFeedbackPlantCoefficients<1, 1, 1>(A, B, C, D, U_max, U_min);
+}
+
+StateFeedbackController<1, 1, 1> MakeCIMController() {
+  Eigen::Matrix<double, 1, 1> L;
+  L << 0.773924473544;
+  Eigen::Matrix<double, 1, 1> K;
+  K << 0.086473980503;
+  Eigen::Matrix<double, 1, 1> A_inv;
+  A_inv << 1.2756330919;
+  return StateFeedbackController<1, 1, 1>(L, K, A_inv, MakeCIMPlantCoefficients());
+}
+
+StateFeedbackPlant<1, 1, 1> MakeCIMPlant() {
+  ::std::vector< ::std::unique_ptr<StateFeedbackPlantCoefficients<1, 1, 1>>> plants(1);
+  plants[0] = ::std::unique_ptr<StateFeedbackPlantCoefficients<1, 1, 1>>(new StateFeedbackPlantCoefficients<1, 1, 1>(MakeCIMPlantCoefficients()));
+  return StateFeedbackPlant<1, 1, 1>(&plants);
+}
+
+StateFeedbackLoop<1, 1, 1> MakeCIMLoop() {
+  ::std::vector< ::std::unique_ptr<StateFeedbackController<1, 1, 1>>> controllers(1);
+  controllers[0] = ::std::unique_ptr<StateFeedbackController<1, 1, 1>>(new StateFeedbackController<1, 1, 1>(MakeCIMController()));
+  return StateFeedbackLoop<1, 1, 1>(&controllers);
+}
+
+}  // namespace control_loops
+}  // namespace frc971
diff --git a/y2015/control_loops/drivetrain/polydrivetrain_cim_plant.h b/y2015/control_loops/drivetrain/polydrivetrain_cim_plant.h
new file mode 100644
index 0000000..1c445a7
--- /dev/null
+++ b/y2015/control_loops/drivetrain/polydrivetrain_cim_plant.h
@@ -0,0 +1,20 @@
+#ifndef Y2015_CONTROL_LOOPS_DRIVETRAIN_POLYDRIVETRAIN_CIM_PLANT_H_
+#define Y2015_CONTROL_LOOPS_DRIVETRAIN_POLYDRIVETRAIN_CIM_PLANT_H_
+
+#include "frc971/control_loops/state_feedback_loop.h"
+
+namespace frc971 {
+namespace control_loops {
+
+StateFeedbackPlantCoefficients<1, 1, 1> MakeCIMPlantCoefficients();
+
+StateFeedbackController<1, 1, 1> MakeCIMController();
+
+StateFeedbackPlant<1, 1, 1> MakeCIMPlant();
+
+StateFeedbackLoop<1, 1, 1> MakeCIMLoop();
+
+}  // namespace control_loops
+}  // namespace frc971
+
+#endif  // Y2015_CONTROL_LOOPS_DRIVETRAIN_POLYDRIVETRAIN_CIM_PLANT_H_
diff --git a/y2015/control_loops/drivetrain/polydrivetrain_dog_motor_plant.cc b/y2015/control_loops/drivetrain/polydrivetrain_dog_motor_plant.cc
new file mode 100644
index 0000000..811991c
--- /dev/null
+++ b/y2015/control_loops/drivetrain/polydrivetrain_dog_motor_plant.cc
@@ -0,0 +1,133 @@
+#include "y2015/control_loops/drivetrain/polydrivetrain_dog_motor_plant.h"
+
+#include <vector>
+
+#include "frc971/control_loops/state_feedback_loop.h"
+
+namespace frc971 {
+namespace control_loops {
+
+StateFeedbackPlantCoefficients<2, 2, 2> MakeVelocityDrivetrainLowLowPlantCoefficients() {
+  Eigen::Matrix<double, 2, 2> A;
+  A << 0.955499400541, 0.00962691403749, 0.00962691403749, 0.955499400541;
+  Eigen::Matrix<double, 2, 2> B;
+  B << 0.0164714763931, -0.00356331126397, -0.00356331126397, 0.0164714763931;
+  Eigen::Matrix<double, 2, 2> C;
+  C << 1.0, 0.0, 0.0, 1.0;
+  Eigen::Matrix<double, 2, 2> D;
+  D << 0.0, 0.0, 0.0, 0.0;
+  Eigen::Matrix<double, 2, 1> U_max;
+  U_max << 12.0, 12.0;
+  Eigen::Matrix<double, 2, 1> U_min;
+  U_min << -12.0, -12.0;
+  return StateFeedbackPlantCoefficients<2, 2, 2>(A, B, C, D, U_max, U_min);
+}
+
+StateFeedbackPlantCoefficients<2, 2, 2> MakeVelocityDrivetrainLowHighPlantCoefficients() {
+  Eigen::Matrix<double, 2, 2> A;
+  A << 0.955499400541, 0.00962691403749, 0.00962691403749, 0.955499400541;
+  Eigen::Matrix<double, 2, 2> B;
+  B << 0.0164714763931, -0.00356331126397, -0.00356331126397, 0.0164714763931;
+  Eigen::Matrix<double, 2, 2> C;
+  C << 1.0, 0.0, 0.0, 1.0;
+  Eigen::Matrix<double, 2, 2> D;
+  D << 0.0, 0.0, 0.0, 0.0;
+  Eigen::Matrix<double, 2, 1> U_max;
+  U_max << 12.0, 12.0;
+  Eigen::Matrix<double, 2, 1> U_min;
+  U_min << -12.0, -12.0;
+  return StateFeedbackPlantCoefficients<2, 2, 2>(A, B, C, D, U_max, U_min);
+}
+
+StateFeedbackPlantCoefficients<2, 2, 2> MakeVelocityDrivetrainHighLowPlantCoefficients() {
+  Eigen::Matrix<double, 2, 2> A;
+  A << 0.955499400541, 0.00962691403749, 0.00962691403749, 0.955499400541;
+  Eigen::Matrix<double, 2, 2> B;
+  B << 0.0164714763931, -0.00356331126397, -0.00356331126397, 0.0164714763931;
+  Eigen::Matrix<double, 2, 2> C;
+  C << 1.0, 0.0, 0.0, 1.0;
+  Eigen::Matrix<double, 2, 2> D;
+  D << 0.0, 0.0, 0.0, 0.0;
+  Eigen::Matrix<double, 2, 1> U_max;
+  U_max << 12.0, 12.0;
+  Eigen::Matrix<double, 2, 1> U_min;
+  U_min << -12.0, -12.0;
+  return StateFeedbackPlantCoefficients<2, 2, 2>(A, B, C, D, U_max, U_min);
+}
+
+StateFeedbackPlantCoefficients<2, 2, 2> MakeVelocityDrivetrainHighHighPlantCoefficients() {
+  Eigen::Matrix<double, 2, 2> A;
+  A << 0.955499400541, 0.00962691403749, 0.00962691403749, 0.955499400541;
+  Eigen::Matrix<double, 2, 2> B;
+  B << 0.0164714763931, -0.00356331126397, -0.00356331126397, 0.0164714763931;
+  Eigen::Matrix<double, 2, 2> C;
+  C << 1.0, 0.0, 0.0, 1.0;
+  Eigen::Matrix<double, 2, 2> D;
+  D << 0.0, 0.0, 0.0, 0.0;
+  Eigen::Matrix<double, 2, 1> U_max;
+  U_max << 12.0, 12.0;
+  Eigen::Matrix<double, 2, 1> U_min;
+  U_min << -12.0, -12.0;
+  return StateFeedbackPlantCoefficients<2, 2, 2>(A, B, C, D, U_max, U_min);
+}
+
+StateFeedbackController<2, 2, 2> MakeVelocityDrivetrainLowLowController() {
+  Eigen::Matrix<double, 2, 2> L;
+  L << 0.935499400541, 0.00962691403749, 0.00962691403749, 0.935499400541;
+  Eigen::Matrix<double, 2, 2> K;
+  K << 22.7750288573, 5.51143253556, 5.51143253556, 22.7750288573;
+  Eigen::Matrix<double, 2, 2> A_inv;
+  A_inv << 1.04667938127, -0.010545576923, -0.010545576923, 1.04667938127;
+  return StateFeedbackController<2, 2, 2>(L, K, A_inv, MakeVelocityDrivetrainLowLowPlantCoefficients());
+}
+
+StateFeedbackController<2, 2, 2> MakeVelocityDrivetrainLowHighController() {
+  Eigen::Matrix<double, 2, 2> L;
+  L << 0.935499400541, 0.00962691403749, 0.00962691403749, 0.935499400541;
+  Eigen::Matrix<double, 2, 2> K;
+  K << 22.7750288573, 5.51143253556, 5.51143253556, 22.7750288573;
+  Eigen::Matrix<double, 2, 2> A_inv;
+  A_inv << 1.04667938127, -0.010545576923, -0.010545576923, 1.04667938127;
+  return StateFeedbackController<2, 2, 2>(L, K, A_inv, MakeVelocityDrivetrainLowHighPlantCoefficients());
+}
+
+StateFeedbackController<2, 2, 2> MakeVelocityDrivetrainHighLowController() {
+  Eigen::Matrix<double, 2, 2> L;
+  L << 0.935499400541, 0.00962691403749, 0.00962691403749, 0.935499400541;
+  Eigen::Matrix<double, 2, 2> K;
+  K << 22.7750288573, 5.51143253556, 5.51143253556, 22.7750288573;
+  Eigen::Matrix<double, 2, 2> A_inv;
+  A_inv << 1.04667938127, -0.010545576923, -0.010545576923, 1.04667938127;
+  return StateFeedbackController<2, 2, 2>(L, K, A_inv, MakeVelocityDrivetrainHighLowPlantCoefficients());
+}
+
+StateFeedbackController<2, 2, 2> MakeVelocityDrivetrainHighHighController() {
+  Eigen::Matrix<double, 2, 2> L;
+  L << 0.935499400541, 0.00962691403749, 0.00962691403749, 0.935499400541;
+  Eigen::Matrix<double, 2, 2> K;
+  K << 22.7750288573, 5.51143253556, 5.51143253556, 22.7750288573;
+  Eigen::Matrix<double, 2, 2> A_inv;
+  A_inv << 1.04667938127, -0.010545576923, -0.010545576923, 1.04667938127;
+  return StateFeedbackController<2, 2, 2>(L, K, A_inv, MakeVelocityDrivetrainHighHighPlantCoefficients());
+}
+
+StateFeedbackPlant<2, 2, 2> MakeVelocityDrivetrainPlant() {
+  ::std::vector< ::std::unique_ptr<StateFeedbackPlantCoefficients<2, 2, 2>>> plants(4);
+  plants[0] = ::std::unique_ptr<StateFeedbackPlantCoefficients<2, 2, 2>>(new StateFeedbackPlantCoefficients<2, 2, 2>(MakeVelocityDrivetrainLowLowPlantCoefficients()));
+  plants[1] = ::std::unique_ptr<StateFeedbackPlantCoefficients<2, 2, 2>>(new StateFeedbackPlantCoefficients<2, 2, 2>(MakeVelocityDrivetrainLowHighPlantCoefficients()));
+  plants[2] = ::std::unique_ptr<StateFeedbackPlantCoefficients<2, 2, 2>>(new StateFeedbackPlantCoefficients<2, 2, 2>(MakeVelocityDrivetrainHighLowPlantCoefficients()));
+  plants[3] = ::std::unique_ptr<StateFeedbackPlantCoefficients<2, 2, 2>>(new StateFeedbackPlantCoefficients<2, 2, 2>(MakeVelocityDrivetrainHighHighPlantCoefficients()));
+  return StateFeedbackPlant<2, 2, 2>(&plants);
+}
+
+StateFeedbackLoop<2, 2, 2> MakeVelocityDrivetrainLoop() {
+  ::std::vector< ::std::unique_ptr<StateFeedbackController<2, 2, 2>>> controllers(4);
+  controllers[0] = ::std::unique_ptr<StateFeedbackController<2, 2, 2>>(new StateFeedbackController<2, 2, 2>(MakeVelocityDrivetrainLowLowController()));
+  controllers[1] = ::std::unique_ptr<StateFeedbackController<2, 2, 2>>(new StateFeedbackController<2, 2, 2>(MakeVelocityDrivetrainLowHighController()));
+  controllers[2] = ::std::unique_ptr<StateFeedbackController<2, 2, 2>>(new StateFeedbackController<2, 2, 2>(MakeVelocityDrivetrainHighLowController()));
+  controllers[3] = ::std::unique_ptr<StateFeedbackController<2, 2, 2>>(new StateFeedbackController<2, 2, 2>(MakeVelocityDrivetrainHighHighController()));
+  return StateFeedbackLoop<2, 2, 2>(&controllers);
+}
+
+}  // namespace control_loops
+}  // namespace frc971
diff --git a/y2015/control_loops/drivetrain/polydrivetrain_dog_motor_plant.h b/y2015/control_loops/drivetrain/polydrivetrain_dog_motor_plant.h
new file mode 100644
index 0000000..5a99caf
--- /dev/null
+++ b/y2015/control_loops/drivetrain/polydrivetrain_dog_motor_plant.h
@@ -0,0 +1,32 @@
+#ifndef Y2015_CONTROL_LOOPS_DRIVETRAIN_POLYDRIVETRAIN_DOG_MOTOR_PLANT_H_
+#define Y2015_CONTROL_LOOPS_DRIVETRAIN_POLYDRIVETRAIN_DOG_MOTOR_PLANT_H_
+
+#include "frc971/control_loops/state_feedback_loop.h"
+
+namespace frc971 {
+namespace control_loops {
+
+StateFeedbackPlantCoefficients<2, 2, 2> MakeVelocityDrivetrainLowLowPlantCoefficients();
+
+StateFeedbackController<2, 2, 2> MakeVelocityDrivetrainLowLowController();
+
+StateFeedbackPlantCoefficients<2, 2, 2> MakeVelocityDrivetrainLowHighPlantCoefficients();
+
+StateFeedbackController<2, 2, 2> MakeVelocityDrivetrainLowHighController();
+
+StateFeedbackPlantCoefficients<2, 2, 2> MakeVelocityDrivetrainHighLowPlantCoefficients();
+
+StateFeedbackController<2, 2, 2> MakeVelocityDrivetrainHighLowController();
+
+StateFeedbackPlantCoefficients<2, 2, 2> MakeVelocityDrivetrainHighHighPlantCoefficients();
+
+StateFeedbackController<2, 2, 2> MakeVelocityDrivetrainHighHighController();
+
+StateFeedbackPlant<2, 2, 2> MakeVelocityDrivetrainPlant();
+
+StateFeedbackLoop<2, 2, 2> MakeVelocityDrivetrainLoop();
+
+}  // namespace control_loops
+}  // namespace frc971
+
+#endif  // Y2015_CONTROL_LOOPS_DRIVETRAIN_POLYDRIVETRAIN_DOG_MOTOR_PLANT_H_
diff --git a/y2015/control_loops/drivetrain/replay_drivetrain.cc b/y2015/control_loops/drivetrain/replay_drivetrain.cc
new file mode 100644
index 0000000..030a945
--- /dev/null
+++ b/y2015/control_loops/drivetrain/replay_drivetrain.cc
@@ -0,0 +1,24 @@
+#include "aos/common/controls/replay_control_loop.h"
+#include "aos/linux_code/init.h"
+
+#include "y2015/control_loops/drivetrain/drivetrain.q.h"
+
+// Reads one or more log files and sends out all the queue messages (in the
+// correct order and at the correct time) to feed a "live" drivetrain process.
+
+int main(int argc, char **argv) {
+  if (argc <= 1) {
+    fprintf(stderr, "Need at least one file to replay!\n");
+    return EXIT_FAILURE;
+  }
+
+  ::aos::InitNRT();
+
+  ::aos::controls::ControlLoopReplayer<::frc971::control_loops::DrivetrainQueue>
+      replayer(&::frc971::control_loops::drivetrain_queue, "drivetrain");
+  for (int i = 1; i < argc; ++i) {
+    replayer.ProcessFile(argv[i]);
+  }
+
+  ::aos::Cleanup();
+}