Add ball detector and only intake if we have a ball.

Change-Id: Id72dde414d6dcddd8721056efdee3e5f25900a3a
diff --git a/y2016/queues/BUILD b/y2016/queues/BUILD
index 3b282fd..81f75d4 100644
--- a/y2016/queues/BUILD
+++ b/y2016/queues/BUILD
@@ -3,6 +3,13 @@
 load('/aos/build/queues', 'queue_library')
 
 queue_library(
+  name = 'ball_detector',
+  srcs = [
+    'ball_detector.q',
+  ],
+)
+
+queue_library(
   name = 'profile_params',
   srcs = [
     'profile_params.q',
diff --git a/y2016/queues/ball_detector.q b/y2016/queues/ball_detector.q
new file mode 100644
index 0000000..948cc25
--- /dev/null
+++ b/y2016/queues/ball_detector.q
@@ -0,0 +1,13 @@
+package y2016.sensors;
+
+message BallDetector {
+  // Voltage measured by the ball detector sensor.
+
+  // Higher voltage means ball is closer to detector, lower voltage means ball
+  // is far from the sensor or not in the robot at all.
+  // TODO(comran): Check to see if our sensor's output corresponds with the
+  // comment above.
+
+  double voltage;
+};
+queue BallDetector ball_detector;