Fix for unhandled TKOFF_THR_MAX

ArduPlane/servos.cpp

@@ -521,12 +521,10 @@ float Plane::apply_throttle_limits(float throttle_in)
 
     // Query the conditions where TKOFF_THR_MAX applies.
     const bool use_takeoff_throttle =
-#if HAL_QUADPLANE_ENABLED
-        quadplane.in_transition() ||
-#endif
         (flight_stage == AP_FixedWing::FlightStage::TAKEOFF) ||
         (flight_stage == AP_FixedWing::FlightStage::ABORT_LANDING);
 
+    // Handle throttle limits for takeoff conditions.
     if (use_takeoff_throttle) {
         if (aparm.takeoff_throttle_max != 0) {
             // Replace max throttle with the takeoff max throttle setting.
@@ -539,7 +537,11 @@ float Plane::apply_throttle_limits(float throttle_in)
         const bool use_throttle_range = (aparm.takeoff_options & (uint32_t)AP_FixedWing::TakeoffOption::THROTTLE_RANGE);
         if (!use_throttle_range || !ahrs.using_airspeed_sensor()) {
             // Use a constant max throttle throughout the takeoff or when airspeed readings are not available.
-            min_throttle = MAX(min_throttle, aparm.takeoff_throttle_max.get());
+            if (aparm.takeoff_throttle_max.get() == 0) {
+                min_throttle = MAX(min_throttle, aparm.throttle_max.get());
+            } else {
+                min_throttle = MAX(min_throttle, aparm.takeoff_throttle_max.get());
+            }
         } else if (use_throttle_range) { // Use a throttle range through the takeoff.
             if (aparm.takeoff_throttle_min.get() != 0) { // This is enabled by TKOFF_MODE==1.
                 min_throttle = MAX(min_throttle, aparm.takeoff_throttle_min.get());
@@ -551,6 +553,15 @@ float Plane::apply_throttle_limits(float throttle_in)
         min_throttle = 0;
     }
 
+    // Handle throttle limits for transition conditions.
+#if HAL_QUADPLANE_ENABLED
+    if (quadplane.in_transition()) {
+        if (aparm.takeoff_throttle_max != 0) {
+            max_throttle = aparm.takeoff_throttle_max.get();
+        }
+    }
+#endif
+
     // Compensate the limits for battery voltage drop.
     // This relaxes the limits when the battery is getting depleted.
     g2.fwd_batt_cmp.apply_min_max(min_throttle, max_throttle);

ArduPlane/takeoff.cpp

@@ -232,7 +232,8 @@ void Plane::takeoff_calc_throttle(const bool use_max_throttle) {
     // Set the minimum throttle limit.
     const bool use_throttle_range = (aparm.takeoff_options & (uint32_t)AP_FixedWing::TakeoffOption::THROTTLE_RANGE);
     if (!use_throttle_range || !ahrs.using_airspeed_sensor() || use_max_throttle) { // Traditional takeoff throttle limit.
-        TECS_controller.set_throttle_min(0.01f*aparm.takeoff_throttle_max);
+        float min_throttle = (aparm.takeoff_throttle_max != 0) ? 0.01f*aparm.takeoff_throttle_max : 0.01f*aparm.throttle_max;
+        TECS_controller.set_throttle_min(min_throttle);
     } else { // TKOFF_MODE == 1, allow for a throttle range.
         if (aparm.takeoff_throttle_min != 0) { // Override THR_MIN.
             TECS_controller.set_throttle_min(0.01f*aparm.takeoff_throttle_min);

Tools/autotest/arduplane.py

@@ -4714,6 +4714,46 @@ def TakeoffTakeoff3(self):
 
         self.fly_home_land_and_disarm()
 
+    def TakeoffTakeoff4(self):
+        '''Test the behaviour of a takeoff in TAKEOFF mode, pt4.
+
+        This is the same as case #3, but with almost stock parameters and without a catapult.
+
+        Conditions:
+        - ARSPD_USE=0
+        '''
+
+        self.customise_SITL_commandline(
+            [],
+            model='plane-catapult',
+            defaults_filepath=self.model_defaults_filepath("plane")
+        )
+        self.set_parameters({
+            "ARSPD_USE": 0.0,
+        })
+        self.change_mode("TAKEOFF")
+
+        self.wait_ready_to_arm()
+        self.arm_vehicle()
+
+        # Check whether we're at max throttle below TKOFF_LVL_ALT.
+        test_alt = self.get_parameter("TKOFF_LVL_ALT")-10
+        self.wait_altitude(test_alt, test_alt+2, relative=True)
+        self.assert_servo_channel_value(3, 1000+10*(self.get_parameter("THR_MAX")), operator.le)
+        self.assert_servo_channel_value(3, 1000+10*(self.get_parameter("THR_MAX"))-10, operator.ge)
+
+        # Check whether we're still at max throttle past TKOFF_LVL_ALT.
+        test_alt = self.get_parameter("TKOFF_LVL_ALT")+10
+        self.wait_altitude(test_alt, test_alt+2, relative=True)
+        self.assert_servo_channel_value(3, 1000+10*(self.get_parameter("THR_MAX")), operator.le)
+        self.assert_servo_channel_value(3, 1000+10*(self.get_parameter("THR_MAX"))-10, operator.ge)
+
+        # Wait for the takeoff to complete.
+        target_alt = self.get_parameter("TKOFF_ALT")
+        self.wait_altitude(target_alt-5, target_alt, relative=True)
+
+        self.fly_home_land_and_disarm()
+
     def DCMFallback(self):
         '''Really annoy the EKF and force fallback'''
         self.reboot_sitl()
@@ -6062,6 +6102,7 @@ def tests(self):
             self.TakeoffTakeoff1,
             self.TakeoffTakeoff2,
             self.TakeoffTakeoff3,
+            self.TakeoffTakeoff4,
             self.ForcedDCM,
             self.DCMFallback,
             self.MAVFTP,