Setting the homepoint and EKF Origin via script?

Christian81 · June 27, 2022, 2:09pm

Hello,

I´m not sure if my question will fit in this sub category, if it is the wrong one, pls move it.

We have build a rover for inspection applications. We use the Pixhawk Orange with the latest firmware and Encoder motors.

The telemetry works, we can see the distance to home etc.

What I would like to have is an easy option for the customer to set the home point and EKF Origin via Herelink. So far we need to go via Mission Planner and set this.

Would there be a way, to do this via a script and press of a button on the herelink controller?

Mustafa_Gokce · June 27, 2022, 8:35pm

I think this can be achieved via LUA scripting.
Take a look at below examples.

github.com

ArduPilot/ardupilot/blob/master/libraries/AP_Scripting/examples/ahrs-set-origin.lua

-- example script for using "set_origin()"" and "initialised()"
-- sets the ekf origin if not already set


function update ()

    if not ahrs:initialised() then
        return update, 5000
    end
    
    origin = assert(not ahrs:get_origin(),"Refused to set EKF origin - already set")
    location = Location() location:lat(-353632640) location:lng(1491652352) location:alt(58409)
    
    if ahrs:set_origin(location) then
        gcs:send_text(6, string.format("Origin Set - Lat:%.7f Long:%.7f Alt:%.1f", location:lat()/10000000, location:lng()/10000000, location:alt()/100))
    else
        gcs:send_text(0, "Refused to set EKF origin")
    end

    return

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github.com

ArduPilot/ardupilot/blob/master/libraries/AP_Scripting/examples/ahrs-set-home-to-vehicle-location.lua

-- example script for using "set_home()"
-- sets the home location to the current vehicle location every 5 seconds

function update ()

    if ahrs:home_is_set() then
        ahrs:set_home(ahrs:get_location())
        gcs:send_text(0, "Home position reset")
    end

    return update, 5000

end

return update()

github.com

ArduPilot/ardupilot/blob/master/libraries/AP_Scripting/examples/RCIN_test.lua

-- example of getting RC input

local scripting_rc_1 = rc:find_channel_for_option(300)
local scripting_rc_2 = rc:find_channel_for_option(301)
local flip_flop = 0

function update()
  pwm1 = rc:get_pwm(1)
  pwm2 = rc:get_pwm(2)
  pwm3 = rc:get_pwm(3)
  pwm4 = rc:get_pwm(4)
  gcs:send_text(0, "RCIN 1:" .. tostring(pwm1) .. " 2:" .. tostring(pwm2).. " 3:" .. tostring(pwm3).. " 4:" .. tostring(pwm4))

  -- read normalized input from designated scripting RCx_OPTION
  if scripting_rc_1 then
    gcs:send_text(0, "Scripting in 1:" .. tostring(scripting_rc_1:norm_input()))
  end

  -- read switch input from second designated scripting RCx_OPTION
  if scripting_rc_2 then

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rmackay9 · June 28, 2022, 1:21am

I agree with @Mustafa_Gokce that this should be possible with a lua script. Remember the EKF origin can only be set once but home can be set as many times as you’d like.

Webillo · June 28, 2022, 8:44am

Yes, it works very well. Even GPS coordinates don’t need to be the real ones; they need just to be correct ‘relative’. I suppose that Guided mode works but I have pending to try it. I wonder if the compass is strictly necessary.

What I couldn’t make work is rotation (ATT.DesYaw=0).

Christian81 · June 28, 2022, 8:23pm

Thank you for the feedback @Mustafa_Gokce and @rmackay9 , the script works fine for setting EKF and Home. But could not get the one working with RC channel, but I need to mention, that I do not have any experience with LUA scripts and I´m just happy I got the first one working

Just one question, the wiki says:

https://ardupilot.org/copter/docs/common-lua-scripts.html

Can I assign here also a RC channel to a script? So if the rover starts, the scripts starts and if I switch the channel it will run the script again?

rmackay9 · June 28, 2022, 11:11pm

@Christian81,

No, but a script can monitor an RC channel and then do something.

Christian81 · June 28, 2022, 11:29pm

@rmackay9

Thank you for the info. I tried it again with RCIN script, but could not get it to work. Would anyone have an idea how the script should look like, that will run the AHRS script again, if the RC channel is used?