Tuned drivetrain kalman filter.

Change-Id: I630770a1331cf896bc6d2de6a58fee880c0185c3
diff --git a/y2014/control_loops/drivetrain/ssdrivetrain.h b/y2014/control_loops/drivetrain/ssdrivetrain.h
index f79a993..5945f96 100644
--- a/y2014/control_loops/drivetrain/ssdrivetrain.h
+++ b/y2014/control_loops/drivetrain/ssdrivetrain.h
@@ -51,6 +51,9 @@
     return loop_->X_hat(0, 0);
   }
 
+  double left_velocity() const { return loop_->X_hat(1, 0); }
+  double right_velocity() const { return loop_->X_hat(3, 0); }
+
   double GetEstimatedRightEncoder() const {
     return loop_->X_hat(2, 0);
   }