Plane: tilt quadplane fixes #28960

tridge · 2024-12-29T01:40:44Z

this fixes some issues with tilt quadplanes.
The first fix is to ensure we don't complete the transition till the rotors are fully tilted forward. The demanded VTOL throttle during the 2nd stage of the transition is also fixed to be based on the tilt angle, not the time.
The 2nd fix is to prevent oscillation of the assisted_flight flag

fixes some of the issues in #28957

tridge · 2025-01-03T22:44:52Z

@IamPete1 I've added a patch to allow THR_SLEWRATE to apply to tilted motors, by adding a new k_throttle_tilt actuator function

this copes with a Q_TILT_RATE_DN that is too slow for the configured Q_TRANSITION_MS

use the proportion we have moved the tilt rotors forward for controlling the VTOL throttle in transition. This prevents a too short Q_TRANSITION_MS from causing oscillations in transition

it makes no sense for it to be above AIRSPEED_MIN

used for slew limiting tilted motors

this reduces the sudden change in throttle on fwd transition completion and allows for THR_SLEWRATE to work on tilt quadplanes

IamPete1 · 2025-01-04T17:57:54Z

ArduPlane/tiltrotor.cpp

@@ -229,7 +231,9 @@ void Tiltrotor::continuous_update(void)

        max_change = tilt_max_change(false);

-        float new_throttle = constrain_float(SRV_Channels::get_output_scaled(SRV_Channel::k_throttle)*0.01, 0, 1);


I was expecting to just be able to change this to get_slew_limited_output_scaled, but I guess that does not slew step when we change over from VTOL to FW throttle?

IamPete1 · 2025-01-04T17:58:29Z

ArduPlane/tiltrotor.cpp

@@ -150,6 +150,8 @@ void Tiltrotor::setup()
    }
    quadplane.transition = transition;

+    SRV_Channels::set_range(SRV_Channel::k_throttle_tilt, 100); // match k_throttle


I really would like to get everything to use a range of 1. But I do see that it would be a bit odd to not match throttle here.

IamPete1 · 2025-01-04T18:00:19Z

ArduPlane/tiltrotor.cpp

@@ -229,7 +231,9 @@ void Tiltrotor::continuous_update(void)

        max_change = tilt_max_change(false);

-        float new_throttle = constrain_float(SRV_Channels::get_output_scaled(SRV_Channel::k_throttle)*0.01, 0, 1);
+        SRV_Channels::set_output_scaled(SRV_Channel::k_throttle_tilt, SRV_Channels::get_output_scaled(SRV_Channel::k_throttle));


I think this should constrain to not be negative before the set. Normal throttle can be negative.

Suggested change

SRV_Channels::set_output_scaled(SRV_Channel::k_throttle_tilt, SRV_Channels::get_output_scaled(SRV_Channel::k_throttle));

SRV_Channels::set_output_scaled(SRV_Channel::k_throttle_tilt, MAX(0, SRV_Channels::get_output_scaled(SRV_Channel::k_throttle)));

IamPete1 · 2025-01-04T18:01:47Z

ArduPlane/tiltrotor.cpp

-        float new_throttle = constrain_float(SRV_Channels::get_output_scaled(SRV_Channel::k_throttle)*0.01, 0, 1);
+        SRV_Channels::set_output_scaled(SRV_Channel::k_throttle_tilt, SRV_Channels::get_output_scaled(SRV_Channel::k_throttle));
+        float new_throttle = constrain_float(SRV_Channels::get_slew_limited_output_scaled(SRV_Channel::k_throttle_tilt)*0.01, 0, 1);
+
        if (current_tilt < get_fully_forward_tilt()) {
            current_throttle = constrain_float(new_throttle,


This constrain could be achieved with the new slew limited function.

IamPete1 · 2025-01-04T18:02:22Z

ArduPlane/tiltrotor.cpp

@@ -245,7 +249,7 @@ void Tiltrotor::continuous_update(void)
        }
        if (!quadplane.motor_test.running) {
            // the motors are all the way forward, start using them for fwd thrust
-            const uint16_t mask = is_zero(current_throttle)?0U:tilt_mask.get();
+            const uint16_t mask = tilt_mask.get();


I think will mean you get spin min in motor test rather than no motors spinning?

IamPete1 · 2025-01-04T18:10:42Z

ArduPlane/tiltrotor.cpp

+    if (!fully_fwd()) {
+        SRV_Channels::set_output_scaled(SRV_Channel::k_throttle_tilt, largest_tilted*100);
+    }


I guess this is to make sure the slew starts off in the right place? I would prefer to see it done with the throttle output value from motors. You should be able to use motors thrust linearisation like we do for tailsitter here:

ardupilot/ArduPlane/tailsitter.cpp

Lines 321 to 323 in 5f8a655

// convert the hover throttle to the same output that would result if used via AP_Motors

// apply expo, battery scaling and SPIN min/max.

throttle = motors->thr_lin.thrust_to_actuator(throttle);

IamPete1 · 2025-01-04T18:11:58Z

libraries/SRV_Channel/SRV_Channel.h

@@ -189,6 +189,7 @@ class SRV_Channel {
        k_rcin15_mapped         = 154,
        k_rcin16_mapped         = 155,
        k_lift_release          = 156,
+        k_throttle_tilt         = 157,


Should we enforce that users don't assign this to a actual output? It does not abide by safety state for example (or E-stop).

IamPete1 · 2025-01-05T17:36:20Z

#29011 is a alternate approach to get slew limiting for tiltrottor throttle outputs.

tridge requested a review from IamPete1 December 29, 2024 01:40

tridge added 6 commits January 4, 2025 12:56

Plane: wait for full tilt to complete tilt quadplane transition

600f432

this copes with a Q_TILT_RATE_DN that is too slow for the configured Q_TRANSITION_MS

Plane: improved handling of tilt quadplane fwd completion

d8c3e2a

use the proportion we have moved the tilt rotors forward for controlling the VTOL throttle in transition. This prevents a too short Q_TRANSITION_MS from causing oscillations in transition

Tools: fixed default SITL Q_ASSIST_SPEED

c229f66

it makes no sense for it to be above AIRSPEED_MIN

autotest: fixed Q_ASSIST test

60c1807

SRV_Channel: added k_throttle_tilt

d7bf02b

used for slew limiting tilted motors

Plane: slew limit tilted motor throttles

77f37b1

this reduces the sudden change in throttle on fwd transition completion and allows for THR_SLEWRATE to work on tilt quadplanes

tridge force-pushed the pr-tilt-fixes branch from ed37cd3 to 77f37b1 Compare January 4, 2025 01:56

IamPete1 reviewed Jan 4, 2025

View reviewed changes

IamPete1 mentioned this pull request Jan 5, 2025

Plane: pass throttle slew limit to motors output_motor_mask function. #29011

Open

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Plane: tilt quadplane fixes #28960

Plane: tilt quadplane fixes #28960

tridge commented Dec 29, 2024

tridge commented Jan 3, 2025

IamPete1 Jan 4, 2025

IamPete1 Jan 4, 2025

IamPete1 Jan 4, 2025

IamPete1 Jan 4, 2025

IamPete1 Jan 4, 2025

IamPete1 Jan 4, 2025

IamPete1 Jan 4, 2025

IamPete1 commented Jan 5, 2025

		@@ -229,7 +231,9 @@ void Tiltrotor::continuous_update(void)

		max_change = tilt_max_change(false);

		float new_throttle = constrain_float(SRV_Channels::get_output_scaled(SRV_Channel::k_throttle)*0.01, 0, 1);

	SRV_Channels::set_output_scaled(SRV_Channel::k_throttle_tilt, SRV_Channels::get_output_scaled(SRV_Channel::k_throttle));
	SRV_Channels::set_output_scaled(SRV_Channel::k_throttle_tilt, MAX(0, SRV_Channels::get_output_scaled(SRV_Channel::k_throttle)));

	// convert the hover throttle to the same output that would result if used via AP_Motors
	// apply expo, battery scaling and SPIN min/max.
	throttle = motors->thr_lin.thrust_to_actuator(throttle);

Plane: tilt quadplane fixes #28960

Are you sure you want to change the base?

Plane: tilt quadplane fixes #28960

Conversation

tridge commented Dec 29, 2024

tridge commented Jan 3, 2025

IamPete1 Jan 4, 2025

Choose a reason for hiding this comment

IamPete1 Jan 4, 2025

Choose a reason for hiding this comment

IamPete1 Jan 4, 2025

Choose a reason for hiding this comment

IamPete1 Jan 4, 2025

Choose a reason for hiding this comment

IamPete1 Jan 4, 2025

Choose a reason for hiding this comment

IamPete1 Jan 4, 2025

Choose a reason for hiding this comment

IamPete1 Jan 4, 2025

Choose a reason for hiding this comment

IamPete1 commented Jan 5, 2025