Turn off sprayer pump when tank gets empty using lua scripting

ArduCopter Copter 4.5
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1

Hey, I’m building an agricultural drone (hexacopter). But unfortunately the current ardupilot codebase doesnt offer all functionalities I need. For example: During spraying, whenever the tank gets empty (flow meter rate becomes zero), the pump should turn off.
My task is to build a new firmware by making some necessary changes in the source code for this purpose. Any suggestion on where and how to make the changes would be appreciated.

2

Look up LUA scripting for Ardupilot. Almost everything can be done with it.
https://ardupilot.org/copter/docs/common-lua-scripts.html

3

Hey thanks…but how can i create new firmware by making some changes in lua script

4

that’s the point of LUA scripting, you don’t need to build a custom firmware to run scripts that perform tasks the original fw wasn’t capable of.

2 Likes
5 
-- Lua script for ArduPilot Copter

-- Check if BATT_MONITOR parameter is 11
local batt_monitor = param:get("BATT_MONITOR")
if batt_monitor ~= 11 then
    return -- Exit the script if BATT_MONITOR is not 11
end

-- Define the RC channel for the pump
local pump_channel = 6

-- Define the threshold for battery current
local current_threshold = 100

-- Function to turn the pump off
local function turn_off_pump()
    rc:set_output_pwm(pump_channel, 1051) -- Set RC channel to minimum to turn off the pump
end

-- Function to monitor battery current and control the pump
local function monitor_battery_and_control_pump()
    -- Check if the pump is turned on (RC channel value is above 1500)
    if rc:get_pwm(pump_channel) > 1200 then
        -- Wait for 2 seconds
        local wait_time = 500
        local start_time = millis()
        while millis() - start_time < wait_time do
            -- Wait loop
        end
        
        -- Monitor battery current
        while true do
            local current_amps = battery:current_amps(0) -- Get the current from battery 0
            if current_amps < current_threshold then
                turn_off_pump() -- Turn off the pump if current is below threshold
                gcs:send_text(0,"Pumps will be turned off")
                return -- Exit the function to keep the pump off
            end
            
        end
    end
end

-- Main loop to periodically check the pump status and monitor battery
function update()
    monitor_battery_and_control_pump()
    return update, 1000 -- Run the update function every second
end

return update()

Hey @Eosbandi this is the script i have written to turn off my pump whenever my pump rate goes below certain value. But I dont think this is working. Any modifications to the script that you would like to suggest?

6

Do not do wait loop in a script, is must return within a certain time (set via a param) or it will be terminated.
Use the update loop and some variables to implement waiting within doe not hold up the script.

1 Like
7

hey, thanks man. I got it working by making some changes in the script

1 Like
8

Publish it here for other users to see.

1 Like