校准第二支路热流体能量与管路摩擦

app/simulation/solvers/mechanical.py

@@ -60,6 +60,20 @@ class MechanicalConstraintGroup:
     def _boundary_tolerance(bound: float) -> float:
         return 1.0e-12 * max(abs(bound), 1.0)
 
+    @staticmethod
+    def _velocity_tolerance(velocity: float) -> float:
+        """Treat only floating-point-scale motion as stationary at a stop.
+
+        Implicit solvers perturb every state while constructing a numerical
+        Jacobian.  Around an ideal endstop those perturbations must not switch
+        the unilateral constraint on and off; doing so turns a zero constrained
+        acceleration into the full outward-force acceleration across a
+        machine-scale velocity delta.  The tolerance is deliberately far below
+        MECMAS21's physical ``dvel`` threshold so real release motion is kept.
+        """
+
+        return 1.0e-12 * max(abs(velocity), 1.0)
+
     def reset_mode(self) -> None:
         self.mode = "uninitialized"
 
@@ -131,6 +145,7 @@ class MechanicalConstraintGroup:
     def _static_endstop_side(self, total_force: float) -> str | None:
         position = self.representative.x
         velocity = self.representative.v
+        velocity_tolerance = self._velocity_tolerance(velocity)
         lower = self.lower_bound
         upper = self.upper_bound
         # MECMAS21's dvel is the friction stick threshold.  Its discrete
@@ -138,14 +153,14 @@ class MechanicalConstraintGroup:
         if (
             lower is not None
             and position <= lower + self._boundary_tolerance(lower)
-            and velocity <= 0.0
+            and velocity <= velocity_tolerance
             and total_force <= 0.0
         ):
             return "lower"
         if (
             upper is not None
             and position >= upper - self._boundary_tolerance(upper)
-            and velocity >= 0.0
+            and velocity >= -velocity_tolerance
             and total_force >= 0.0
         ):
             return "upper"
@@ -489,6 +504,8 @@ class MechanicalStateReducer:
             position_index = velocity_index + 1
             previous_velocity = float(previous_state[velocity_index])
             current_velocity = float(current_state[velocity_index])
+            previous_velocity_tolerance = group._velocity_tolerance(previous_velocity)
+            current_velocity_tolerance = group._velocity_tolerance(current_velocity)
             previous_position = float(previous_state[position_index])
             current_position = float(current_state[position_index])
             lower = group.lower_bound
@@ -496,7 +513,7 @@ class MechanicalStateReducer:
             if (
                 lower is not None
                 and previous_position <= lower + group._boundary_tolerance(lower)
-                and previous_velocity < 0.0
+                and previous_velocity < -previous_velocity_tolerance
             ):
                 candidates.append((previous_time, group, "lower", lower))
             elif (
@@ -522,8 +539,8 @@ class MechanicalStateReducer:
             elif (
                 lower is not None
                 and previous_position <= lower
-                and previous_velocity > 0.0
-                and current_velocity < 0.0
+                and previous_velocity > previous_velocity_tolerance
+                and current_velocity < -current_velocity_tolerance
                 and current_position <= lower
             ):
                 turnaround_time = self._locate_turnaround(
@@ -551,7 +568,7 @@ class MechanicalStateReducer:
             if (
                 upper is not None
                 and previous_position >= upper - group._boundary_tolerance(upper)
-                and previous_velocity > 0.0
+                and previous_velocity > previous_velocity_tolerance
             ):
                 candidates.append((previous_time, group, "upper", upper))
             elif (
@@ -577,8 +594,8 @@ class MechanicalStateReducer:
             elif (
                 upper is not None
                 and previous_position >= upper
-                and previous_velocity < 0.0
-                and current_velocity > 0.0
+                and previous_velocity < -previous_velocity_tolerance
+                and current_velocity > current_velocity_tolerance
                 and current_position >= upper
             ):
                 turnaround_time = self._locate_turnaround(