Add landing gear tutorial and default instructions

[LorenzMeier]

• Gear switch: RC_MAP_GEAR_SW - set it to the RC channel you want it to be on
• You need a gear mixer to pass the gear channel to the AUX outputs:

  
  #
  # This maps actuator_controls_0[7] (gear) to the first PWM output
  #

M: 1 O: 10000 10000 0 -10000 10000 S: 0 7 10000 10000 0 -10000 10000

  * The gear mixer needs to be loaded:

#

Load the gear mixer onto fmu

# mixer load /dev/px4fmu /etc/mixers/gear.mix

[dagar]

Longer term could we find a way to do this without having to deal with a mixer?

I'm also wondering if it would make sense to move things like landing gear to a separate control group and handle it outside of the attitude controllers. That module could have landing gear config via param and would be accessible for both MC and FW.

[matanhavi]

Is there way to control the landing gear by mavlink? Does they controlled by logic? for example, during RTL, does it goes down automatically?

[dagar]

@matanhavi for a multicopter yes it will go down automatically.

[matanhavi]

@dagar Thanks, I will try it. Does it have option to be controlled by mavlink? and/or how they goes up? I tried to find the related code, to follow the logic, without success.

[dagar]

Here for AUTO - https://github.com/PX4/Firmware/blob/master/src/modules/mc_pos_control/mc_pos_control_main.cpp#L1560

[PX4BuildBot]

Hey, this issue has been closed because the label status/STALE is set and there were no updates for 30 days. Feel free to reopen this issue if you deem it appropriate.

(This is an automated comment from GitMate.io.)

[mattgorski]

I would like to see more documentation on how to automate this when using gamepad/joystick inplace of RC. Would I just load the mixer and also what is the proper way to load this mixer put on microsd in /etc/mixer does this need a config.txt? Thanks in advance.

[hamishwillee]

Reopening - the tutorial does not exist, so this work has not been done. Probably this should be in the PX4 user guide or devguide issue tracker.

@dagar

1. Above you suggested that we should improve the system so that mixer not required (YES). Did this happen? We have RC_MAP_GEAR_SW to map channel to gear switch, but I envisage we're talking a second parameter to map RC_MAP_GEAR_SW to a specific MAIN or AUX (or could this be on some other bus - ie UAVCAN?)
2. You also suggested factoring this so that it could be used on all vehicle types - did that happen? So auto landing not supported on VTOL or FW?
3. Generally you'd add the mixer etc as per http://dev.px4.io/en/advanced/system_startup.html#customizing-the-system-startup ?

4. 10279 asks about Joystick button mapping. Do you happen to know if there is any equivalent to RC_MAP_GEAR_SW for mapping joystick buttons. Certainly this is not supported via the UI: https://docs.qgroundcontrol.com/en/SetupView/Joystick.html (or is this a "Don/Gus" question?)

[mattgorski]

I am going to assume that we need to add a config.txt with the following correct (along with gear.mix above)?

set MIXER_AUX gear set PWM_AUX_OUT 1234 set PWM_AUX_DISARMED 1500 set PWM_AUX_MIN 1000 set PWM_AUX_MAX 2000 set PWM_AUX_RATE 50

[dagar]

The portion that applies to multicopter and RC_MAP_GEAR_SW is in reasonably good shape, but FW and joystick button mapping is still missing.

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[hamishwillee]

@dagar I assume you still want to improve the architecture around this as per https://github.com/PX4/Firmware/issues/7458#issuecomment-310419573

Otherwise, if we want to document this as it is now there is not enough info - see my post: https://github.com/PX4/Firmware/issues/7458#issuecomment-414621313

[stale[bot]]

Closing as stale.