Store Q/R in StateFeedbackObserverCoefficients

I want R available to get noise values for use in the EKF. I pull in Q
because I may want it and it doesn't really cost us anything.

Change-Id: I7eae2669333cf8eac99a05d10b1d2cefa305cc2f
diff --git a/frc971/control_loops/hybrid_state_feedback_loop_test.cc b/frc971/control_loops/hybrid_state_feedback_loop_test.cc
index 42433e9..38dbd53 100644
--- a/frc971/control_loops/hybrid_state_feedback_loop_test.cc
+++ b/frc971/control_loops/hybrid_state_feedback_loop_test.cc
@@ -150,7 +150,9 @@
   ::std::vector<::std::unique_ptr<StateFeedbackObserverCoefficients<2, 4, 7>>>
       v_observer;
   v_observer.emplace_back(new StateFeedbackObserverCoefficients<2, 4, 7>(
-      Eigen::Matrix<double, 2, 7>::Identity()));
+      Eigen::Matrix<double, 2, 7>::Identity(),
+      Eigen::Matrix<double, 2, 2>::Identity(),
+      Eigen::Matrix<double, 7, 7>::Identity()));
   StateFeedbackObserver<2, 4, 7> observer(&v_observer);
 
   StateFeedbackLoop<2, 4, 7> test_loop(
diff --git a/frc971/control_loops/python/control_loop.py b/frc971/control_loops/python/control_loop.py
index 9aa00df..e3e00b7 100644
--- a/frc971/control_loops/python/control_loop.py
+++ b/frc971/control_loops/python/control_loop.py
@@ -453,10 +453,17 @@
     if observer_coefficient_type.startswith('StateFeedbackObserver'):
       if hasattr(self, 'KalmanGain'):
         KalmanGain = self.KalmanGain
+        Q = self.Q
+        R = self.R
       else:
         KalmanGain =  numpy.linalg.inv(self.A) * self.L
+        Q = numpy.zeros(self.A.shape)
+        R = numpy.zeros((self.C.shape[0], self.C.shape[0]))
       ans.append(self._DumpMatrix('KalmanGain', KalmanGain, scalar_type))
-      ans.append('  return %s(KalmanGain);\n' % (observer_coefficient_type,))
+      ans.append(self._DumpMatrix('Q', Q, scalar_type))
+      ans.append(self._DumpMatrix('R', R, scalar_type))
+      ans.append('  return %s(KalmanGain, Q, R);\n'
+          % (observer_coefficient_type,))
 
     elif observer_coefficient_type.startswith('HybridKalman'):
       ans.append(self._DumpMatrix('Q_continuous', self.Q_continuous, scalar_type))
diff --git a/frc971/control_loops/python/drivetrain.py b/frc971/control_loops/python/drivetrain.py
index 3f9123f..c59cbab 100644
--- a/frc971/control_loops/python/drivetrain.py
+++ b/frc971/control_loops/python/drivetrain.py
@@ -362,10 +362,15 @@
         self.KalmanGain, self.Q_steady = controls.kalman(
             A=self.A, B=self.B, C=self.C, Q=self.Q, R=self.R)
 
+        # If we don't have an IMU, pad various matrices with zeros so that
+        # we can still have 4 measurement outputs.
         if not self.has_imu:
             self.KalmanGain = numpy.hstack((self.KalmanGain, numpy.matrix(numpy.zeros((7, 1)))))
             self.C = numpy.vstack((self.C, numpy.matrix(numpy.zeros((1, 7)))))
             self.D = numpy.vstack((self.D, numpy.matrix(numpy.zeros((1, 2)))))
+            Rtmp = numpy.zeros((4, 4))
+            Rtmp[0:3, 0:3] = self.R
+            self.R = Rtmp
 
         self.L = self.A * self.KalmanGain
 
diff --git a/frc971/control_loops/state_feedback_loop.h b/frc971/control_loops/state_feedback_loop.h
index 2511d98..fc3ff34 100644
--- a/frc971/control_loops/state_feedback_loop.h
+++ b/frc971/control_loops/state_feedback_loop.h
@@ -275,10 +275,15 @@
   EIGEN_MAKE_ALIGNED_OPERATOR_NEW;
 
   const Eigen::Matrix<Scalar, number_of_states, number_of_outputs> KalmanGain;
+  const Eigen::Matrix<Scalar, number_of_states, number_of_states> Q;
+  const Eigen::Matrix<Scalar, number_of_outputs, number_of_outputs> R;
 
   StateFeedbackObserverCoefficients(
-      const Eigen::Matrix<Scalar, number_of_states, number_of_outputs> &KalmanGain)
-      : KalmanGain(KalmanGain) {}
+      const Eigen::Matrix<Scalar, number_of_states, number_of_outputs> &
+          KalmanGain,
+      const Eigen::Matrix<Scalar, number_of_states, number_of_states> &Q,
+      const Eigen::Matrix<Scalar, number_of_outputs, number_of_outputs> &R)
+      : KalmanGain(KalmanGain), Q(Q), R(R) {}
 };
 
 template <int number_of_states, int number_of_inputs, int number_of_outputs,