Tune the spline controller for auto modes

Use the "regular" kalman filter's velocity estimates, since those will
be more stable in the presence of localizer updates.

Change-Id: I9decb651cbdc4a6cf0642ea576c6840e90988803
Signed-off-by: James Kuszmaul <jabukuszmaul+collab@gmail.com>
diff --git a/frc971/control_loops/drivetrain/drivetrain.h b/frc971/control_loops/drivetrain/drivetrain.h
index 0d100ed..f448760 100644
--- a/frc971/control_loops/drivetrain/drivetrain.h
+++ b/frc971/control_loops/drivetrain/drivetrain.h
@@ -67,9 +67,10 @@
 
   // Returns the current localizer state.
   Eigen::Matrix<double, 5, 1> trajectory_state() {
+    // Use the regular kalman filter's left/right velocity because they are
+    // generally smoother.
     return (Eigen::Matrix<double, 5, 1>() << localizer_->x(), localizer_->y(),
-            localizer_->theta(), localizer_->left_velocity(),
-            localizer_->right_velocity())
+            localizer_->theta(), DrivetrainXHat()(1), DrivetrainXHat()(3))
         .finished();
   }