Add param COM_PREARM_MODE #12806

jlecoeur · 2019-08-25T13:02:14Z

replacement of #12713

Add param COM_PREARM_MODE
Condition to enter the prearmed state, an intermediate state between disarmed and armed
in which non-throttling actuators are active.
value 0 Disabled
value 1 Safety button
value 2 Always
IO: respect actuator_armed.prearmed flag
Arm non-throttling actuators on IO only when the prearmed flag is set.
(Same behaviour as FMU).

dagar · 2019-08-25T14:16:53Z

This looks good, although we need to decide if the default behavior should change.

Condition to enter the prearmed state, an intermediate state between disarmed and armed * in which non-throttling actuators are active. * * @value 0 Disabled * @value 1 Safety button * @value 2 Always

jlecoeur · 2019-08-25T14:53:21Z

Modified to keep same behaviour for safety button users, and make the system safer by default for the others (with the option to opt-in for the less safe behaviour)

Antiheavy · 2019-08-25T15:38:59Z

@jlecoeur can you help translate for me how this could affect our use case scenario?

Our use case as follows:

Fixed Wing
No safety button
No RC input (no manual)
upon boot system goes into Manual mode, servos are energized at neutral, but do not move
upon solid GPS lock (and Home position established), the system automatically switches to Hold mode (i believe because no RC input?) and servos start stabilizing (rate damping?).

We like the above behavior because 1) servos are energized, but not moving around during indoor handling, 2) Servos start moving is an easy indicator of "ready" in outdoor handling and used in our preflight checklist.

jlecoeur · 2019-08-25T15:44:59Z

@Antiheavy you will keep the same behaviour by setting COM_PREARM_MODE to ALWAYS.

Antiheavy · 2019-08-25T15:52:03Z

@jlecoeur okay thanks.
FYI @Kjkinney

src/modules/commander/Commander.cpp

src/modules/px4iofirmware/protocol.h

dannyfpv · 2019-08-26T21:37:36Z

teste on pixhawk4 v5 f-450
Modes Tested
Position Mode: Good.
Altitude Mode: Good.
Stabilized Mode: Good.
Mission Plan Mode (Automated): Good.

log:
https://review.px4.io/plot_app?log=60990dfd-0b59-4144-bf09-d2a574e41452

teste on pixhawk1 v2 fantom wing
Modes Tested
Altitude Mode: no rc response th, ail, elev
Stabilized Mode: Good.
Mission Plan Mode (Automated): Good.

log:
https://review.px4.io/plot_app?log=fae7a3ed-93e2-4fbe-af5e-2b411efad1bf

jorge789 · 2019-08-26T21:45:38Z

Tested on PixRacer V4:
Modes Tested

Position Mode: Good.
Altitude Mode: Good.
Stabilized Mode: Good.
Mission Plan Mode (Automated): Good.
RTL: Good.

- Procedure
Arm and Take off in position mode, after flying for approximately one minute, switched to altitude then stabilized mode proceed to switch to mission plan mode then make sure that vehicle follows all waypoints as shown in QGC, once completed all waypoin activate RTL and see landing behaviour.

Notes:
No issues noted, good flight in general.

Log:
https://review.px4.io/plot_app?log=d0d66690-64d7-4857-befc-4af5aac8eb5b

Tested on CUAC+ V5:
Modes Tested

Position Mode: Good.
Altitude Mode: Good.
Stabilized Mode: Good.
Mission Plan Mode (Automated): Good.
RTL: Good.

- Procedure
Arm and Take off in position mode, after flying for approximately one minute, switched to altitude then stabilized mode proceed to switch to mission plan mode then make sure that vehicle follows all waypoints as shown in QGC, once completed all waypoin activate RTL and see landing behaviour.

Notes:
No issues noted, good flight in general.

Log:
https://review.px4.io/plot_app?log=9a6c859e-5974-45ca-b451-7b67c0571c81

Junkim3DR · 2019-08-26T22:00:31Z

Tested on Pixhawk 4Mini v5

Modes Tested

Position Mode: Good.
Altitude Mode: Good.
Stabilized Mode: Good.
Mission Plan Mode (Automated): Good.
RTL: Good.

Procedure
Arm and Take off in position mode, after flying for approximately one minute, switched to altitude then stabilized mode proceed to switch to mission plan mode then make sure that vehicle follows all waypoints as shown in QGC, once completed all waypoint activate RTL and see landing behaviour.

Notes:
No issues noted, good flight in general.

Log:
https://review.px4.io/plot_app?log=60549622-b259-45fd-92c2-ba88dc616bdd

Tested on NXP FMUK66 v3

Modes Tested

Position Mode: Good.
Altitude Mode: Good.
Stabilized Mode: Good.
Mission Plan Mode (Automated): Good.
RTL: Good.

Procedure
Arm and Take off in position mode, after flying for approximately one minute, switched to altitude then stabilized mode proceed to switch to mission plan mode then make sure that vehicle follows all waypoints as shown in QGC, once completed all waypoint activate RTL and see landing behaviour.

Notes:
No issues noted, good flight in general.

Log:
https://review.px4.io/plot_app?log=0bfad336-a490-417f-a837-79d25142743e

hamishwillee · 2019-08-27T23:23:43Z

src/modules/commander/commander_params.c

+ * Condition to enter prearmed mode
+ *
+ * Condition to enter the prearmed state, an intermediate state between disarmed and armed
+ * in which non-throttling actuators are active.


What is a non-throttling activator?

A non throttling actuator is an actuator that does not drive a motor/engine. The underlying assumption is that throttling actuator is dangerous and should not move until the system is armed, while non-throttling actuators (ailerons, flaps, camera gimbal, etc) are safer and can move before the system is armed.

Right now, throttling actuator is defined here (NaN means the actuator will stay in disarmed position) https://github.com/PX4/Firmware/blob/a20b508d7e60a1332e3c9ff18d69df4d5e04eb5d/src/drivers/px4fmu/fmu.cpp#L1062-L1070. But I would not bother documenting that too precisely as this is likely to change when we introduce metadata at the mixer level to indicate which output is safe to prearm.

hamishwillee · 2019-08-27T23:27:03Z

src/modules/commander/commander_params.c

+ * Condition to enter the prearmed state, an intermediate state between disarmed and armed
+ * in which non-throttling actuators are active.
+ *
+ * @value 0 Disabled


So would I be correct in saying

Disabled means that this mode doesn't exist - if you try and arm you just go from disarmed to armed.

Safety button means that you enter this mode when you press the safety button. How then do you move forward to armed?

Always means that you just go to this mode.

Does this require any docs/mention other than in the param? Frankly I don't understand what it is for, how you move to armed from this state, what an end user needs to do, or when they would set it.

You are correct.

How then do you move forward to armed?

As usual: arm switch, or arm stick motion, or MAVLink command

Does this require any docs/mention other than in the param?

Frankly I think some doc is needed here.
In fact, I was not aware of this state before I loaded a custom mixer on an airframe with the safety switch disabled (CBRK_IO_SAFETY), and the actuators started moving right after plugging the battery! This is now fixed with this PR: if you disable the safety switch the system will not prearm on its own by default.

From the user perspective, "prearmed" means "my ailerons move but my propellers do not spin".

In the default case of a system with safety button (COM_PREARM_MODE=Safety button and CBRK_IO_SAFETY=0), the behaviour is

power up

all actuators are locked into disarmed position, it is not possible to arm

safety switch is pressed. The system is now prearmed: non-throttling actuators start moving. System safety is off: it is now possible to arm

arm command is issued: The system is armed: all actuators move

Now the non default cases:
COM_PREARM_MODE=Disabled:

power up

all actuators are locked into disarmed position, it is not possible to arm

safety switch is pressed. All actuators stay locked into disarmed position. System safety is off: it is now possible to arm

arm command is issued: The system is armed: all actuators move

COM_PREARM_MODE=Always:

power up

The system is now prearmed: non-throttling actuators start moving. Safety is on: it is not possible to arm

safety switch is pressed. System safety is off: it is now possible to arm

arm command is issued: The system is armed: all actuators move

And now for systems without safety button.

COM_PREARM_MODE=Safety button and CBRK_IO_SAFETY is engaged:

power up

all actuators are locked into disarmed position. System safety is off: it is possible to arm.

arm command is issued: The system is armed: all actuators move

COM_PREARM_MODE=Disabled and CBRK_IO_SAFETY is engaged:
Same as above

COM_PREARM_MODE=Always and CBRK_IO_SAFETY is engaged:

power up

The system is now prearmed: non-throttling actuators start moving. Safety is off: it is possible to arm.

arm command is issued: The system is armed: all actuators move

Thank you! I have created PX4/PX4-user_guide#567 to track this. I won't have time for it this week - feel free to find a place where you think docs should go if you need it in earlier.

bresch

Seems good. I'm also in favor of keeping the current logic as default.

hamishwillee · 2019-09-03T04:44:29Z

@jlecoeur Can you please review docs for this: PX4/PX4-user_guide#569

jlecoeur added the Feature: Safety label Aug 25, 2019

jlecoeur requested review from dagar, julianoes and bresch August 25, 2019 13:02

jlecoeur force-pushed the pr-cbrk_prearmed_en branch from 1b3dda8 to 49e5d75 Compare August 25, 2019 14:48

jlecoeur changed the title ~~Add param CBRK_PREARMED_EN~~ Add param COM_PREARM_MODE Aug 25, 2019

jlecoeur added 2 commits August 25, 2019 16:51

Add parameter COM_PREARM_MODE

0b51053

Condition to enter the prearmed state, an intermediate state between disarmed and armed * in which non-throttling actuators are active. * * @value 0 Disabled * @value 1 Safety button * @value 2 Always

IO: respect actuator_armed.prearmed flag

755f764

jlecoeur force-pushed the pr-cbrk_prearmed_en branch from 49e5d75 to 755f764 Compare August 25, 2019 14:51

jlecoeur mentioned this pull request Aug 25, 2019

Add parameter COM_PREARM_LOCK to lock actuators when prearmed #12713

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julianoes reviewed Aug 26, 2019

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Merge branch 'master' into pr-cbrk_prearmed_en

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hamishwillee mentioned this pull request Aug 28, 2019

COM_PREARM_MODE Docs needed PX4/PX4-user_guide#567

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Weekly Digest (25 August, 2019 - 1 September, 2019) #12858

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dagar added 2 commits September 1, 2019 14:06

Merge branch 'master' into pr-cbrk_prearmed_en

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Weekly Digest (1 September, 2019 - 8 September, 2019) #12924

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Add param COM_PREARM_MODE #12806

Add param COM_PREARM_MODE #12806

jlecoeur commented Aug 25, 2019 •

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hamishwillee commented Sep 3, 2019

Add param COM_PREARM_MODE #12806

Add param COM_PREARM_MODE #12806

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Junkim3DR commented Aug 26, 2019

Tested on Pixhawk 4Mini v5

Tested on NXP FMUK66 v3

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