make head accesible on lh backends

pylabrobot/liquid_handling/backends/backend.py

@@ -1,7 +1,7 @@
 from __future__ import annotations
 
 from abc import ABCMeta, abstractmethod
-from typing import List, Optional, Union
+from typing import Dict, List, Optional, Union
 
 from pylabrobot.liquid_handling.standard import (
   Aspiration,
@@ -20,6 +20,7 @@
 )
 from pylabrobot.machines.backends import MachineBackend
 from pylabrobot.resources import Deck, Resource
+from pylabrobot.resources.tip_tracker import TipTracker
 
 
 class LiquidHandlerBackend(MachineBackend, metaclass=ABCMeta):
@@ -36,17 +37,34 @@ class LiquidHandlerBackend(MachineBackend, metaclass=ABCMeta):
   def __init__(self):
     self.setup_finished = False
     self._deck: Optional[Deck] = None
+    self._head: Optional[Dict[int, TipTracker]] = None
+    self._head96: Optional[Dict[int, TipTracker]] = None
 
   def set_deck(self, deck: Deck):
     """Set the deck for the robot. Called automatically by `LiquidHandler.setup` or can be called
     manually if interacting with the backend directly. A deck must be set before setup."""
     self._deck = deck
 
+  def set_heads(self, head: Dict[int, TipTracker], head96: Optional[Dict[int, TipTracker]] = None):
+    """Set the tip tracker for the robot. Called automatically by `LiquidHandler.setup` or can be
+    called manually if interacting with the backend directly. A head must be set before setup."""
+    self._head = head
+    self._head96 = head96
+
   @property
   def deck(self) -> Deck:
     assert self._deck is not None, "Deck not set"
     return self._deck
 
+  @property
+  def head(self) -> Dict[int, TipTracker]:
+    assert self._head is not None, "Head not set"
+    return self._head
+
+  @property
+  def head96(self) -> Optional[Dict[int, TipTracker]]:
+    return self._head96
+
   async def setup(self):
     """Set up the robot. This method should be called before any other method is called."""
     assert self._deck is not None, "Deck not set"

pylabrobot/liquid_handling/backends/hamilton/STAR.py

@@ -7317,58 +7317,6 @@ async def clld_probe_z_height_using_channel(
 
     return result_in_mm
 
-  async def request_tip_len_on_channel(
-    self,
-    channel_idx: int,  # 0-based indexing of channels!
-  ) -> float:
-    """
-    Measures the length of the tip attached to the specified pipetting channel.
-
-    Checks if a tip is present on the given channel. If present, moves all channels
-    to THE safe Z position, 334.3 mm, measures the tip bottom Z-coordinate, and calculates
-    the total tip length. Supports tips of lengths 50.4 mm, 59.9 mm, and 95.1 mm.
-    Raises an error if the tip length is unsupported or if no tip is present.
-
-    Parameters:
-      channel_idx: Index of the pipetting channel (0-based).
-
-    Returns:
-      The measured tip length in millimeters.
-
-    Raises:
-      ValueError: If no tip is present on the channel or if the tip length is unsupported.
-    """
-
-    # Check there is a tip on the channel
-    all_channel_occupancy = await self.request_tip_presence()
-    if not all_channel_occupancy[channel_idx]:
-      raise ValueError(f"No tip present on channel {channel_idx}")
-
-    # Level all channels
-    await self.move_all_channels_in_z_safety()
-    known_top_position_channel_head = 334.3  # mm
-    fitting_depth_of_all_standard_channel_tips = 8  # mm
-    unknown_offset_for_all_tips = 0.4  # mm
-
-    # Request z-coordinate of channel+tip bottom
-    tip_bottom_z_coordinate = await self.request_z_pos_channel_n(
-      pipetting_channel_index=channel_idx
-    )
-
-    total_tip_len = round(
-      known_top_position_channel_head
-      - (
-        tip_bottom_z_coordinate
-        - fitting_depth_of_all_standard_channel_tips
-        - unknown_offset_for_all_tips
-      ),
-      1,
-    )
-
-    if total_tip_len in [50.4, 59.9, 95.1]:  # 50ul, 300ul, 1000ul
-      return total_tip_len
-    raise ValueError(f"Tip of length {total_tip_len} not yet supported")
-
   async def ztouch_probe_z_height_using_channel(
     self,
     channel_idx: int,  # 0-based indexing of channels!
@@ -7389,6 +7337,8 @@ async def ztouch_probe_z_height_using_channel(
 
     Args:
       channel_idx: The index of the channel to use for probing. Backmost channel = 0.
+      tip_len: override the tip length (of tip on channel `channel_idx`). Default is the tip length
+        of the tip that was picked up.
       lowest_immers_pos: The lowest immersion position in mm.
       start_pos_lld_search: The start position for z-touch search in mm.
       channel_speed: The speed of channel movement in mm/sec.
@@ -7414,10 +7364,12 @@ async def ztouch_probe_z_height_using_channel(
           f"found version '{version}'"
         )
 
-    fitting_depth = 8  # mm, for 10, 50, 300, 1000 ul Hamilton tips
-
     if tip_len is None:
-      tip_len = await self.request_tip_len_on_channel(channel_idx=channel_idx)
+      tip_len = self.head[channel_idx].get_tip().total_tip_length
+
+    # fitting_depth = 8 mm for 10, 50, 300, 1000 ul Hamilton tips
+    fitting_depth = self.head[channel_idx].get_tip().fitting_depth
+
     if start_pos_search is None:
       start_pos_search = 334.7 - tip_len + fitting_depth
 

pylabrobot/liquid_handling/liquid_handler.py

@@ -173,6 +173,7 @@ async def setup(self, **backend_kwargs):
       raise RuntimeError("The setup has already finished. See `LiquidHandler.stop`.")
 
     self.backend.set_deck(self.deck)
+    self.backend.set_heads(head=self.head, head96=self.head96)
     await super().setup(**backend_kwargs)
 
     self.head = {c: TipTracker(thing=f"Channel {c}") for c in range(self.backend.num_channels)}