RpmControl: Better consider the case where there's no rpm measurement…

… (anymore)

msg/Rpm.msg

@@ -1,4 +1,5 @@
 uint64 timestamp # time since system start (microseconds)
 
+# rpm values of 0.0 mean within a timeout there is no movement measured
 float32 rpm_estimate # filtered revolutions per minute
 float32 rpm_raw

src/modules/control_allocator/ActuatorEffectiveness/RpmControl.cpp

@@ -68,11 +68,15 @@ float RpmControl::getActuatorCorrection()
 			const float gain_scale = math::interpolate(_spoolup_progress, .8f, 1.f, 0.f, 1e-3f);
 			_pid.setGains(_param_ca_heli_rpm_p.get() * gain_scale, _param_ca_heli_rpm_i.get() * gain_scale, 0.f);
 			_actuator_correction = _pid.update(rpm.rpm_estimate, dt, true);
+
+			_rpm_invalid = rpm.rpm_estimate < 1.f;
 		}
 	}
 
 	// Timeout
-	if (now > _timestamp_last_measurement + 1_s) {
+	const bool timeout = now > _timestamp_last_measurement + 1_s;
+
+	if (_rpm_invalid || timeout) {
 		_pid.resetIntegral();
 		_actuator_correction = 0.f;
 	}

src/modules/control_allocator/ActuatorEffectiveness/RpmControl.hpp

@@ -63,6 +63,7 @@ class RpmControl : public ModuleParams
 	static constexpr float PID_OUTPUT_LIMIT = .5f; // [0,1]
 
 	uORB::Subscription _rpm_sub{ORB_ID(rpm)};
+	bool _rpm_invalid{true};
 	PID _pid;
 	float _spoolup_progress{0.f}; // [0,1]
 	hrt_abstime _timestamp_last_measurement{0}; // for dt and timeout