对laiyu移液站进行部分修改，取消多次初始化的问题

unilabos/devices/liquid_handling/liquid_handler_abstract.py

@@ -581,16 +581,51 @@ class LiquidHandlerAbstract(LiquidHandlerMiddleware):
     support_touch_tip = True
     _ros_node: BaseROS2DeviceNode
 
-    def __init__(self, backend: LiquidHandlerBackend, deck: Deck, simulator: bool=False, channel_num:int = 8):
+    def __init__(self, backend: LiquidHandlerBackend, deck: Deck, simulator: bool=False, channel_num:int = 8, total_height:float = 310):
         """Initialize a LiquidHandler.
 
         Args:
           backend: Backend to use.
           deck: Deck to use.
         """
+        backend_type = None
+        if isinstance(backend, dict) and "type" in backend:
+            backend_dict = backend.copy()
+            type_str = backend_dict.pop("type")
+            try:
+                # Try to get class from string using globals (current module), or fallback to pylabrobot or unilabos namespaces
+                backend_cls = None
+                if type_str in globals():
+                    backend_cls = globals()[type_str]
+                else:
+                    # Try resolving dotted notation, e.g. "xxx.yyy.ClassName"
+                    components = type_str.split(".")
+                    mod = None
+                    if len(components) > 1:
+                        module_name = ".".join(components[:-1])
+                        try:
+                            import importlib
+                            mod = importlib.import_module(module_name)
+                        except ImportError:
+                            mod = None
+                        if mod is not None:
+                            backend_cls = getattr(mod, components[-1], None)
+                    if backend_cls is None:
+                        # Try pylabrobot style import (if available)
+                        try:
+                            import pylabrobot
+                            backend_cls = getattr(pylabrobot, type_str, None)
+                        except Exception:
+                            backend_cls = None
+                if backend_cls is not None and isinstance(backend_cls, type):
+                    backend_type = backend_cls(**backend_dict)  # pass the rest of dict as kwargs
+            except Exception as exc:
+                raise RuntimeError(f"Failed to convert backend type '{type_str}' to class: {exc}")
+        else:
+            backend_type = backend
         self._simulator = simulator
         self.group_info = dict()
-        super().__init__(backend, deck, simulator, channel_num)
+        super().__init__(backend_type, deck, simulator, channel_num)
 
     def post_init(self, ros_node: BaseROS2DeviceNode):
         self._ros_node = ros_node