Enable UART6 and enable S.BUS. Tested to work.

src/modules/attitude_estimator_q/attitude_estimator_q_main.cpp

@@ -206,6 +206,8 @@ private:
 
 
 AttitudeEstimatorQ::AttitudeEstimatorQ() :
+	_vel_prev(0, 0, 0),
+	_pos_acc(0, 0, 0),
 	_voter_gyro(3),
 	_voter_accel(3),
 	_voter_mag(3),
@@ -725,6 +727,8 @@ bool AttitudeEstimatorQ::update(float dt)
 		corr += _q.conjugate_inversed(Vector<3>(0.0f, 0.0f, -mag_err)) * _w_mag;
 	}
 
+	_q.normalize();
+
 	// Accelerometer correction
 	// Project 'k' unit vector of earth frame to body frame
 	// Vector<3> k = _q.conjugate_inversed(Vector<3>(0.0f, 0.0f, 1.0f));

src/modules/sensors/sensors.cpp

@@ -846,7 +846,7 @@ Sensors::parameters_update()
 	} else if (_parameters.battery_voltage_scaling < 0.0f) {
 		/* apply scaling according to defaults if set to default */
 
-#ifdef CONFIG_ARCH_BOARD_PX4FMU_V2
+#if defined (CONFIG_ARCH_BOARD_PX4FMU_V2) || defined (CONFIG_ARCH_BOARD_PX4FMU_V4)
 		_parameters.battery_voltage_scaling = 0.0082f;
 #elif CONFIG_ARCH_BOARD_AEROCORE
 		_parameters.battery_voltage_scaling = 0.0063f;