feat(long): gentler stop

openpilot/selfdrive/controls/lib/drive_helpers.py

@@ -14,8 +14,11 @@ MAX_LATERAL_JERK = 5.0  # m/s^3
 MAX_LATERAL_ACCEL_NO_ROLL = 3.0  # m/s^2
 
 
+STOPPING_SPEED = 0.25  # m/s, speed at which the car goes into the stopping state
+
+
 def should_stop(v_ego: float, a_target: float) -> bool:
-  return bool(v_ego < 0.3 and a_target < 0.1)
+  return bool(v_ego < STOPPING_SPEED and a_target < 0.1)
 
 def clamp(val, min_val, max_val):
   clamped_val = float(np.clip(val, min_val, max_val))

openpilot/selfdrive/controls/lib/longcontrol.py

@@ -7,6 +7,8 @@ from openpilot.selfdrive.modeld.constants import ModelConstants
 
 CONTROL_N_T_IDX = ModelConstants.T_IDXS[:CONTROL_N]
 
+STOPPING_DECEL_RATE = 0.3  # m/s^2/s while trying to stop
+
 LongCtrlState = car.CarControl.Actuators.LongControlState
 
 
@@ -68,7 +70,7 @@ class LongControl:
       if output_accel > self.CP.stopAccel:
         output_accel = min(output_accel, 0.0)
         # TODO: can we just go straight to stopAccel?
-        output_accel -= 1.0 * DT_CTRL  # m/s^2/s while trying to stop
+        output_accel -= STOPPING_DECEL_RATE * DT_CTRL
       self.reset()
 
     else:  # LongCtrlState.pid

openpilot/selfdrive/controls/tests/test_longcontrol.py

@@ -1,6 +1,7 @@
 from openpilot.common.test import OpenpilotTestCase
 from openpilot.cereal import custom
-from openpilot.selfdrive.controls.lib.longcontrol import LongCtrlState, long_control_state_trans
+from openpilot.selfdrive.controls.lib.drive_helpers import STOPPING_SPEED, should_stop
+from openpilot.selfdrive.controls.lib.longcontrol import STOPPING_DECEL_RATE, LongCtrlState, long_control_state_trans
 
 
 class TestLongControlStateTransition(OpenpilotTestCase):
@@ -42,3 +43,13 @@ class TestLongControlStateTransition(OpenpilotTestCase):
     next_state = long_control_state_trans(CP_SP, active, current_state,
                              should_stop=False, brake_pressed=False, cruise_standstill=False)
     assert next_state == LongCtrlState.pid
+
+class TestTerminalStop(OpenpilotTestCase):
+  def test_stopping_tune_is_gentler_than_upstream_default(self):
+    # Upstream #38394 hardcoded a 1.0 m/s^2/s ramp and a 0.3 m/s latch. comma's own one-stopping-tune uses
+    # 0.3 / 0.25, and every stop recorded on this car was driven with that pair. Both must stay on the less
+    # braking side, or a future edit re-deepens the terminal brake unnoticed - which already happened once.
+    assert 0.0 < STOPPING_DECEL_RATE <= 1.0
+    assert 0.0 < STOPPING_SPEED <= 0.3
+    assert should_stop(STOPPING_SPEED - 0.01, 0.0)
+    assert not should_stop(0.29, 0.0)  # the band upstream would latch in and we do not