Move GNSS distance to reference check to field navigation (#273)

We mostly use straight line indoors without a sufficient gnss signal, so
the navigation fails.
This PR just warns the user when using a normal navigation without valid
gnss. When running the field navigation it fails, because we definitely
need it there.

field_friend/automations/navigation/field_navigation.py

@@ -11,6 +11,7 @@
 from ..field import Field, Row
 from ..implements.implement import Implement
 from ..implements.weeding_implement import WeedingImplement
+from .navigation import WorkflowException, is_reference_valid
 from .straight_line_navigation import StraightLineNavigation
 
 if TYPE_CHECKING:
@@ -55,6 +56,12 @@ def current_row(self) -> Row:
         assert self.field
         return self.rows_to_work_on[self.row_index]
 
+    @track
+    async def start(self) -> None:
+        if not is_reference_valid(self.gnss):
+            raise WorkflowException('reference to far away from robot')
+        await super().start()
+
     async def prepare(self) -> bool:
         await super().prepare()
         self.field = self.field_provider.get_field(self.field_id)

field_friend/automations/navigation/navigation.py

@@ -17,16 +17,6 @@
     from ...system import System
 
 
-def is_reference_valid(gnss: Gnss, *, max_distance: float = 5000.0) -> bool:
-    if GeoReference.current is None:
-        return False
-    if gnss.last_measurement is None:
-        return False
-    if gnss.last_measurement.gps_quality == 0:
-        return False
-    return gnss.last_measurement.point.distance(GeoReference.current.origin) <= max_distance
-
-
 class WorkflowException(Exception):
     pass
 
@@ -62,7 +52,8 @@ async def start(self) -> None:
                 self.log.error('Preparation failed')
                 return
             if not is_reference_valid(self.gnss):
-                raise WorkflowException('reference to far away from robot')
+                rosys.notify('GNSS not available or reference too far away', 'warning')
+                await rosys.sleep(3)
             self.start_position = self.robot_locator.pose.point
             if isinstance(self.driver.wheels, rosys.hardware.WheelsSimulation) and not rosys.is_test:
                 self.create_simulation()
@@ -150,3 +141,13 @@ def settings_ui(self) -> None:
             .classes('w-24') \
             .bind_value(self, 'linear_speed_limit') \
             .tooltip(f'Forward speed limit in m/s (default: {self.LINEAR_SPEED_LIMIT:.2f})')
+
+
+def is_reference_valid(gnss: Gnss, *, max_distance: float = 5000.0) -> bool:
+    if GeoReference.current is None:
+        return False
+    if gnss.last_measurement is None:
+        return False
+    if gnss.last_measurement.gps_quality == 0:
+        return False
+    return gnss.last_measurement.point.distance(GeoReference.current.origin) <= max_distance