autotest: add test for Plane's RTL_CLIMB_MIN parameter

Tools/autotest/ArduPlane_Tests/RTL_CLIMB_MIN/flaps.txt

@@ -0,0 +1,13 @@
+QGC WPL 110
+0	0	0	16	0.000000	0.000000	0.000000	0.000000	-35.363262	149.165237	584.390015	1
+1	0	3	22	15.000000	0.000000	0.000000	0.000000	-35.361279	149.164230	30.000000	1
+2	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.361229	149.163025	80.000000	1
+3	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.364563	149.163773	80.000000	1
+4	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.364384	149.164795	80.000000	1
+5	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.361027	149.164093	80.000000	1
+6	0	0	177	2.000000	3.000000	0.000000	0.000000	0.000000	0.000000	0.000000	1
+7	0	3	189	0.000000	0.000000	0.000000	0.000000	-35.362915	149.162613	60.000000	1
+8	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.363136	149.162750	60.000000	1
+9	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.365467	149.164215	55.000000	1
+10	0	3	16	0.000000	0.000000	0.000000	0.000000	-35.365009	149.165482	39.889999	1
+11	0	3	21	0.000000	0.000000	0.000000	1.000000	-35.363041	149.165222	0.000000	1

Tools/autotest/arduplane.py

@@ -1431,6 +1431,49 @@ class AutoTestPlane(AutoTest):
         self.deadreckoning_main()
         self.deadreckoning_main(disable_airspeed_sensor=True)
 
+    def rtl_climb_min(self):
+        self.wait_ready_to_arm()
+        rtl_climb_min = 100
+        self.set_parameter("RTL_CLIMB_MIN", rtl_climb_min)
+        takeoff_alt = 50
+        self.takeoff(alt=takeoff_alt)
+        self.change_mode('CRUISE')
+        self.wait_distance_to_home(1000, 1500, timeout=60)
+        post_cruise_alt = self.get_altitude(relative=True)
+        self.change_mode('RTL')
+        expected_alt = self.get_parameter("ALT_HOLD_RTL")/100.0
+        if expected_alt == -1:
+            expected_alt = self.get_altitude(relative=True)
+
+        # ensure we're about half-way-down at the half-way-home stage:
+        self.wait_distance_to_nav_target(
+            0,
+            500,
+            timeout=120,
+        )
+        alt = self.get_altitude(relative=True)
+        expected_halfway_alt = expected_alt + (post_cruise_alt + rtl_climb_min - expected_alt)/2.0
+        if abs(alt - expected_halfway_alt) > 30:
+            raise NotAchievedException("Not half-way-down and half-way-home (want=%f got=%f" %
+                                       (expected_halfway_alt, alt))
+        self.progress("Half-way-down at half-way-home (want=%f vs got=%f)" %
+                      (expected_halfway_alt, alt))
+
+        rtl_radius = self.get_parameter("RTL_RADIUS")
+        if rtl_radius == 0:
+            rtl_radius = self.get_parameter("WP_LOITER_RAD")
+        self.wait_distance_to_nav_target(
+            0,
+            rtl_radius,
+            timeout=120,
+        )
+        alt = self.get_altitude(relative=True)
+        if abs(alt - expected_alt) > 10:
+            raise NotAchievedException(
+                "Expected to have %fm altitude at end of RTL (got %f)" %
+                (expected_alt, alt))
+        self.fly_home_land_and_disarm()
+
     def sample_enable_parameter(self):
         return "Q_ENABLE"
 
@@ -2376,6 +2419,10 @@ class AutoTestPlane(AutoTest):
              "Test AirSpeed drivers",
              self.test_airspeed_drivers),
 
+            ("RTL_CLIMB_MIN",
+             "Test RTL_CLIMB_MIN",
+             self.rtl_climb_min),
+
             ("IMUTempCal",
              "Test IMU temperature calibration",
              self.test_imu_tempcal),