ardupilot/libraries/AP_Scripting/examples/copter_pingpong.lua

-- This script makes the drone go forward and backward at a defined distance and number of times.
-- The stages are:
-- 0) Change to Guided mode
-- 1) Takeoff to the height defined by takeoff_alt
-- 2) Wait until reaching the takeoff altitude
-- 3) Go forward to the defined distance
-- 4) Go back to the initial position
-- 5) Change to Land mode

local takeoff_alt = 3         -- Takeoff height
local copter_guided_mode_num = 4
local copter_land_mode_num = 9
local stage = 0
local count = 0               -- Number of times the drone has gone forward
local max_count = 2           -- Maximum number of times the drone should go forward
local ping_pong_distance = 10 -- Distance up to which the drone should go forward (m)
local vel = 1                 -- Drone velocity (m/s)

function update()
    -- Checking if the drone is armed
    if not arming:is_armed() then
         -- Reset state when disarmed
        stage = 0
        gcs:send_text(6, "Arming")
    else
        if stage == 0 then      -- Stage0: Change to guided mode
              if vehicle:set_mode(copter_guided_mode_num) then -- Change to Guided mode
                  stage = stage + 1
              end

        elseif stage == 1 then -- Stage1: Takeoff
        gcs:send_text(6, "Taking off")
            if vehicle:start_takeoff(takeoff_alt) then
                stage = stage + 1
            end
            
        elseif stage == 2 then -- Stage2: Check if the vehicle has reached the target altitude
            local home = ahrs:get_home()
            local curr_loc = ahrs:get_position()
            if home and curr_loc then 
                local vec_from_home = home:get_distance_NED(curr_loc)
                gcs:send_text(6, "Altitude above home: " .. tostring(math.floor(-vec_from_home:z())))
                if math.abs(takeoff_alt + vec_from_home:z()) < 1 then
                    stage = stage + 1
                end
            end
        elseif stage == 3 then -- Stage3: Moving Forward
        -- If the number of times is exceeded, switch to stage5
            if count >= max_count then
                stage = stage + 2
            end

                -- Calculate velocity vector
                local target_vel = Vector3f()
                target_vel:x(vel)
                target_vel:y(0)
                target_vel:z(0)

                -- Send velocity request
                if not vehicle:set_target_velocity_NED(target_vel) then
                    gcs:send_text(6, "Failed to execute velocity command")
                end
                
                -- Checking if the stop point is reached
                local home = ahrs:get_home()
                local curr_loc = ahrs:get_position()
                if home and curr_loc then 
                    local vec_from_home = home:get_distance_NED(curr_loc)
                    gcs:send_text(6, "Distance from home: " .. tostring(math.floor(vec_from_home:x())))
                    if math.abs(ping_pong_distance - vec_from_home:x()) < 1 then
                        count = count + 1
                        stage = stage + 1
                    end
                end
            
        elseif stage == 4 then -- Stage4: Moving Back
            -- Calculate velocity vector
            local target_vel = Vector3f()
            target_vel:x(-vel)
            target_vel:y(0)
            target_vel:z(0)

            -- Send velocity request
            if not vehicle:set_target_velocity_NED(target_vel) then
                gcs:send_text(6, "Failed to execute velocity command")
            end
            
            -- Checking if the stop point is reached
            local home = ahrs:get_home()
            local curr_loc = ahrs:get_position()
            if home and curr_loc then 
                local vec_from_home = home:get_distance_NED(curr_loc)
                gcs:send_text(6, "Distance from home: " .. tostring(math.floor(vec_from_home:x())))
                if math.abs(vec_from_home:x()) < 1 then
                    stage = stage - 1
                end
            end
              
          elseif stage == 5 then -- Stage5: Change to land mode
              vehicle:set_mode(copter_land_mode_num)
              stage = stage + 1
              gcs:send_text(6, "Finished pingpong, switching to land")
          end
        end
    return update, 100
end

return update()