Tools: expand autotests for ground effect and VRF bias learning

TakeoffGroundEffectAlt:
- Add subtest for TKOFF_GNDEFF_TMO verifying timeout extends ground effect

VibrationRectificationBiasLearning:
- Add subtest for full bitmask (7) with ground learning inhibit
- Add subtest verifying frozen correction persists across flights

Author: andyp1per

Tools/autotest/arducopter.py

@@ -11914,7 +11914,7 @@ def GroundEffectCompensation_takeOffExpected(self):
                                        (duration, want_lt))
 
     def TakeoffGroundEffectAlt(self):
-        '''Test TKOFF_GNDEFF_ALT controls ground effect altitude threshold'''
+        '''Test TKOFF_GNDEFF_ALT and TKOFF_GNDEFF_TMO control ground effect'''
         self.context_push()
         self.set_parameter("LOG_FILE_DSRMROT", 1)
 
@@ -11949,6 +11949,28 @@ def TakeoffGroundEffectAlt(self):
                 "Smaller threshold should have shorter ground effect (small=%fs >= large=%fs)"
                 % (total_small, total_large))
 
+        # Subtest C: TKOFF_GNDEFF_TMO requires both timeout AND altitude
+        # With small altitude threshold but timeout set, ground effect should persist longer
+        self.start_subtest("TKOFF_GNDEFF_TMO extends ground effect duration")
+        self.set_parameters({
+            "TKOFF_GNDEFF_ALT": 0.5,  # Small threshold - would clear quickly without timeout
+            "TKOFF_GNDEFF_TMO": 3,    # Require 3s timeout as well
+        })
+        self.reboot_sitl()
+        self.takeoff(5, mode='ALT_HOLD')
+        self.delay_sim_time(5)
+        self.change_mode('LAND')
+        self.wait_disarmed()
+        durations_tmo = self.get_takeoffexpected_durations_from_current_onboard_log(ignore_multi=True)
+        total_tmo = sum(durations_tmo)
+        self.progress("takeoff_expected total with GNDEFF_TMO=3: %fs" % total_tmo)
+
+        # With timeout, ground effect should persist longer than without (even with small alt threshold)
+        if total_tmo <= total_small:
+            raise NotAchievedException(
+                "TKOFF_GNDEFF_TMO should extend ground effect (tmo=%fs <= no_tmo=%fs)"
+                % (total_tmo, total_small))
+
         self.context_pop()
         self.reboot_sitl()
 
@@ -11957,18 +11979,17 @@ def VibrationRectificationBiasLearning(self):
         self.context_push()
         # ACC_ZBIAS_LEARN bitmask: 1=learn+save, 2=use, 4=inhibit EKF when disarmed
         # Value 3 = learn+save + use
+        # Reset INS_ACC_VRFB_Z to 0 to ensure clean start (may have leftover from previous tests)
         self.set_parameters({
             "ACC_ZBIAS_LEARN": 3,
             "SIM_ACC1_BIAS_Z": 0.15,
             "LOG_FILE_DSRMROT": 1,
+            "INS_ACC_VRFB_Z": 0,
         })
         self.reboot_sitl()
 
         # A: Verify learning during hover and save on disarm
         self.start_subtest("Bias learned during hover and saved on disarm")
-        vrfb_z = self.get_parameter("INS_ACC_VRFB_Z")
-        if abs(vrfb_z) > 0.001:
-            raise NotAchievedException("INS_ACC_VRFB_Z should start at 0, got %f" % vrfb_z)
         self.wait_ready_to_arm()
         self.takeoff(10, mode='LOITER')
         self.delay_sim_time(30)
@@ -12005,6 +12026,42 @@ def VibrationRectificationBiasLearning(self):
         if abs(vrfb_z) > 0.001:
             raise NotAchievedException("INS_ACC_VRFB_Z should remain 0, got %f" % vrfb_z)
 
+        # D: Verify bit 2 (inhibit EKF ground learning) works with full bitmask
+        # Value 7 = learn+save + use + inhibit ground learning
+        self.start_subtest("Full bitmask (7) with ground learning inhibit")
+        self.set_parameters({
+            "INS_ACC_VRFB_Z": 0,
+            "ACC_ZBIAS_LEARN": 7,
+            "SIM_ACC1_BIAS_Z": 0.15,
+        })
+        self.reboot_sitl()
+        self.wait_ready_to_arm()
+        # Fly and verify learning still works (bit 2 only affects disarmed state)
+        self.takeoff(10, mode='LOITER')
+        self.delay_sim_time(30)
+        self.land_and_disarm()
+        vrfb_z = self.get_parameter("INS_ACC_VRFB_Z")
+        self.progress("INS_ACC_VRFB_Z with full bitmask (7): %f" % vrfb_z)
+        if abs(vrfb_z) < 0.01:
+            raise NotAchievedException(
+                "INS_ACC_VRFB_Z should be non-zero with bitmask 7, got %f" % vrfb_z)
+
+        # E: Verify frozen correction survives flight (proxy for lane switch survival)
+        # After learning, fly again and verify the saved bias is still applied
+        self.start_subtest("Frozen correction persists across flights")
+        saved_vrfb_z = vrfb_z
+        self.reboot_sitl()
+        self.wait_ready_to_arm()
+        self.takeoff(10, mode='LOITER')
+        self.delay_sim_time(10)
+        self.land_and_disarm()
+        vrfb_z = self.get_parameter("INS_ACC_VRFB_Z")
+        # The saved bias should persist (may drift slightly due to continued learning)
+        if abs(vrfb_z) < 0.01:
+            raise NotAchievedException(
+                "INS_ACC_VRFB_Z should persist across flights, got %f" % vrfb_z)
+        self.progress("INS_ACC_VRFB_Z persisted: was %f, now %f" % (saved_vrfb_z, vrfb_z))
+
         self.context_pop()
         self.reboot_sitl()