Copter drifting while using LUA script to fly in a circle

Kasper · February 14, 2023, 1:26pm

I am trying to make my copter goes in circles using this Lua script:

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

-- Commands copter to fly circle trajectory using posvel method in guided mode. 
-- The trajectory start from the current location
-- 
-- CAUTION: This script only works for Copter.
-- This script start when the in GUIDED mode and above 5 meter.
--      1) arm and takeoff to above 5 m 
--      2) switch to GUIDED mode 
--      3) the vehilce will follow a circle in clockwise direction with increasing speed until ramp_up_time_s time has passed.
--      4) switch out of and into the GUIDED mode any time to restart the trajectory from the start.

-- Edit these variables
local rad_xy_m = 10.0   -- circle radius in xy plane in m
local target_speed_xy_mps = 5.0     -- maximum target speed in m/s
local ramp_up_time_s = 10.0     -- time to reach target_speed_xy_mps in second
local sampling_time_s = 0.05    -- sampling time of script

-- Fixed variables
local omega_radps = target_speed_xy_mps/rad_xy_m
local copter_guided_mode_num = 4
local theta = 0.0

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When I tried to fly with the script, the copter started to drift as seen in the image of the flight log below:

I think I am looking for a Lua script that works more like a “waypoint file/mission” where the copter navigates to exact waypoint locations that together make a circle. These waypoint positions need to update so that every time the “Circle Lua Script” is activated, the corresponding circle waypoints are created.

Any ideas that could help me move forward?