Relax collision avoidance if not holding game piece

Change-Id: I361f639460b1fcb2c7c2223d3e4f42ae743b9ad0
diff --git a/y2019/control_loops/superstructure/collision_avoidance.h b/y2019/control_loops/superstructure/collision_avoidance.h
index ca29e7c..7fc80cd 100644
--- a/y2019/control_loops/superstructure/collision_avoidance.h
+++ b/y2019/control_loops/superstructure/collision_avoidance.h
@@ -70,6 +70,7 @@
   // elevator is below kElevatorClearHeight.
   static constexpr double kWristElevatorCollisionMinAngle = -M_PI / 4.0;
   static constexpr double kWristElevatorCollisionMaxAngle = M_PI / 4.0;
+  static constexpr double kWristElevatorCollisionMaxAngleWithoutObject = M_PI / 6.0;
 
   // Tolerance for the elevator.
   static constexpr double kEps = 0.02;