add offset to LH.return_tips96

Author: rickwierenga

pylabrobot/liquid_handling/backends/hamilton/STAR_backend.py

@@ -2228,7 +2228,10 @@ async def drop_tips96(
     if isinstance(drop.resource, TipRack):
       tip_spot_a1 = drop.resource.get_item("A1")
       position = tip_spot_a1.get_absolute_location() + tip_spot_a1.center() + drop.offset
-      position.z += 52.0
+      position.z = tip_spot_a1.parent.get_absolute_location().z + 1.45
+      # This should be the case for all normal hamilton tip carriers + racks
+      # In the future, we might want to make this more flexible
+      assert abs(position.z - 216.4) < 1e-6, f"z position must be 216.4, got {position.z}"
     else:
       position = self._position_96_head_in_resource(drop.resource) + drop.offset
 

pylabrobot/liquid_handling/liquid_handler.py

@@ -1515,7 +1515,7 @@ def _get_96_head_origin_tip_rack(self) -> Optional[TipRack]:
         raise RuntimeError("All tips must be from the same tip rack")
     return tip_rack
 
-  async def return_tips96(self, allow_nonzero_volume: bool = False, **backend_kwargs):
+  async def return_tips96(self, allow_nonzero_volume: bool = False, offset: Coordinate = Coordinate.zero(), **backend_kwargs):
     """Return the tips on the 96 head to the tip rack where they were picked up.
 
     Examples:
@@ -1539,6 +1539,7 @@ async def return_tips96(self, allow_nonzero_volume: bool = False, **backend_kwar
     return await self.drop_tips96(
       tip_rack,
       allow_nonzero_volume=allow_nonzero_volume,
+      offset=offset,
       **backend_kwargs,
     )