Erratic/random heading setpoint when transitioning from FW mode to MC mode for Duo Tailsitter VTOL in mission mode

sven · December 28, 2020, 4:03pm

My VTOL Duo Tailsitter (PX4, fw 1.10.2) performs a smooth back-transition from manual FW-mode to manual MR mode. But when in autonomous-mission mode, the wing executes a weird and quite uncontrolled rotation around the FW-roll-axis (MR-yaw-axis) when transitioning from FW to MR. It looks like some random yaw setpoint is set what doesn’t make sense. Any ideas are appreciated, thanks!

xdwgood · December 29, 2020, 12:21am

@sven I have been working on v1.11. For v1.10.2, the following code shows how the yaw set angle is transmitted in transition mode .

github.com

PX4/PX4-Autopilot/blob/v1.10.2/src/lib/FlightTasks/tasks/Transition/FlightTaskTransition.cpp#L49



bool FlightTaskTransition::updateInitialize()
{
	return FlightTask::updateInitialize();
}

bool FlightTaskTransition::activate(vehicle_local_position_setpoint_s last_setpoint)
{
	checkSetpoints(last_setpoint);
	_transition_altitude = last_setpoint.z;
	_transition_yaw = last_setpoint.yaw;
	_acceleration_setpoint.setAll(0.f);
	_velocity_prev = _velocity;
	return FlightTask::activate(last_setpoint);
}

void FlightTaskTransition::checkSetpoints(vehicle_local_position_setpoint_s &setpoints)
{
	// If the setpoint is unknown, set to the current estimate
	if (!PX4_ISFINITE(setpoints.z)) { setpoints.z = _position(2); }

github.com

PX4/PX4-Autopilot/blob/v1.10.2/src/lib/FlightTasks/tasks/Transition/FlightTaskTransition.cpp#L89


{
	// level wings during the transition, altitude should be controlled
	_thrust_setpoint(0) = _thrust_setpoint(1) = 0.0f;
	_thrust_setpoint(2) = NAN;
	_position_setpoint *= NAN;
	_velocity_setpoint *= NAN;
	_position_setpoint(2) = _transition_altitude;

	updateAccelerationEstimate();

	_yaw_setpoint = _transition_yaw;
	return true;
}

xdwgood · December 29, 2020, 12:23am

I suggest you use v1.11, it may solve many v1.10 problems

sven · December 29, 2020, 4:37am

Thank you very much xdwgood for letting me know where that part of the transition happens, I appreciate your help! I will try to understand what happens here and I will flash 1.11 and give it a try next time at the airfield!