-- switches between AHRS/EKF sources based on the pilot's source selection switch or using an automatic source selection algorithm -- this script is intended to help vehicles automatically switch between GPS and optical flow -- -- configure a forward or downward facing lidar with a range of at least 5m -- setup RCx_OPTION = 90 (EKF Pos Source) to select the source (low=GPS, middle=opticalflow, high=Not Used) -- setup RCx_OPTION = 300 (Scripting1). When this switch is pulled high, the source will be automatically selected -- SRC_ENABLE = 1 (enable scripting) -- setup EK3_SRCn_ parameters so that GPS is the primary source, opticalflow is secondary. -- EK3_SRC1_POSXY = 3 (GPS) -- EK3_SRC1_VELXY = 3 (GPS) -- EK3_SRC1_VELZ = 3 (GPS) -- EK3_SRC1_POSZ = 1 (Baro) -- EK3_SRC1_YAW = 1 (Compass) -- EK3_SRC2_POSXY = 0 (None) -- EK3_SRC2_VELXY = 5 (OpticalFlow) -- EK3_SRC2_VELZ = 0 (None) -- EK3_SRC2_POSZ = 1 (Baro) -- EK3_SRC2_YAW = 1 (Compass) -- EK3_SRC_OPTIONS = 0 (Do not fuse all velocities) -- -- SCR_USER1 holds the threshold (in meters) for rangefinder altitude (around 15 is a good choice) -- if rangefinder distance >= SCR_USER1, source1 (GPS) will be used -- if rangefinder distance < SCR_USER1, source2 (optical flow) will be used if innovations are below SRC_USER3 value -- SCR_USER2 holds the threshold for GPS speed accuracy (around 0.3 is a good choice) -- SCR_USER3 holds the threshold for optical flow quality (about 50 is a good choice) -- SCR_USER4 holds the threshold for optical flow innovations (about 0.15 is a good choice) -- -- When the 2nd auxiliary switch (300/Scripting1) is pulled high automatic source selection uses these thresholds: local rangefinder_rotation = 25 -- check downward (25) facing lidar local source_prev = 0 -- previous source, defaults to primary source local sw_source_prev = -1 -- previous source switch position local sw_auto_pos_prev = -1 -- previous auto source switch position local auto_switch = false -- true when auto switching between sources is active local gps_usable_accuracy = 1.0 -- GPS is usable if speed accuracy is at or below this value local vote_counter_max = 20 -- when a vote counter reaches this number (i.e. 2sec) source may be switched local gps_vs_opticalflow_vote = 0 -- vote counter for GPS vs optical (-20 = GPS, +20 = optical flow) local scr_user1_param = Parameter() -- user1 param (rangefinder altitude threshold) local scr_user2_param = Parameter() -- user2 param (GPS speed accuracy threshold) local scr_user3_param = Parameter() -- user3 param (optical flow quality threshold) local scr_user4_param = Parameter() -- user4 param (optical flow innovation threshold) -- initialise parameters assert(scr_user1_param:init('SCR_USER1'), 'could not find SCR_USER1 parameter') assert(scr_user2_param:init('SCR_USER2'), 'could not find SCR_USER2 parameter') assert(scr_user3_param:init('SCR_USER3'), 'could not find SCR_USER3 parameter') assert(scr_user4_param:init('SCR_USER4'), 'could not find SCR_USER4 parameter') assert(optical_flow, 'could not access optical flow') -- play tune on buzzer to alert user to change in active source set function play_source_tune(source) if (source) then if (source == 0) then notify:play_tune("L8C") -- one long lower tone elseif (source == 1) then notify:play_tune("L12DD") -- two fast medium tones elseif (source == 2) then notify:play_tune("L16FFF") -- three very fast, high tones end end end -- the main update function function update() -- check switches are configured -- at least one switch must be set -- source selection from RCx_FUNCTION = 90 (EKF Source Select) -- auto source from RCx_FUNCTION = 300 (Scripting1) local rc_function_source = rc:find_channel_for_option(90) local rc_function_auto = rc:find_channel_for_option(300) if not rc_function_source and not rc_function_auto then gcs:send_text(0, "ahrs-source-gps-optflow.lua: RCx_FUNCTION=90 or 300 not set!") return update, 1000 end -- check rangefinder distance threshold has been set local rangefinder_thresh_dist = scr_user1_param:get() -- SCR_USER1 holds rangefinder threshold if (rangefinder_thresh_dist <= 0) then gcs:send_text(0, "ahrs-source-gps-optflow.lua: set SCR_USER1 to rangefinder threshold") return update, 1000 end -- check GPS speed accuracy threshold has been set local gps_speedaccuracy_thresh = scr_user2_param:get() -- SCR_USER2 holds GPS speed accuracy threshold if (gps_speedaccuracy_thresh <= 0) then gcs:send_text(0, "ahrs-source-gps-optflow.lua: set SCR_USER2 to GPS speed accuracy threshold") return update, 1000 end -- check optical flow quality threshold has been set local opticalflow_quality_thresh = scr_user3_param:get() -- SCR_USER3 holds opticalflow quality if (opticalflow_quality_thresh <= 0) then gcs:send_text(0, "ahrs-source-gps-optflow.lua: set SCR_USER3 to OpticalFlow quality threshold") return update, 1000 end -- check optical flow innovation threshold has been set local opticalflow_innov_thresh = scr_user4_param:get() -- SCR_USER4 holds opticalflow innovation if (opticalflow_innov_thresh <= 0) then gcs:send_text(0, "ahrs-source-gps-optflow.lua: set SCR_USER4 to OpticalFlow innovation threshold") return update, 1000 end -- check if GPS speed accuracy is over threshold local gps_speed_accuracy = gps:speed_accuracy(gps:primary_sensor()) local gps_over_threshold = (gps_speed_accuracy == nil) or (gps:speed_accuracy(gps:primary_sensor()) > gps_speedaccuracy_thresh) local gps_usable = (gps_speed_accuracy ~= nil) and (gps_speed_accuracy <= gps_usable_accuracy) -- check optical flow quality local opticalflow_quality_good = false if (optical_flow) then opticalflow_quality_good = (optical_flow:enabled() and optical_flow:healthy() and optical_flow:quality() >= opticalflow_quality_thresh) end -- get opticalflow innovations from ahrs (only x and y values are valid) local opticalflow_over_threshold = true local opticalflow_xy_innov = 0 local opticalflow_innov = Vector3f() local opticalflow_var = Vector3f() opticalflow_innov, opticalflow_var = ahrs:get_vel_innovations_and_variances_for_source(5) if (opticalflow_innov) then opticalflow_xy_innov = math.sqrt(opticalflow_innov:x() * opticalflow_innov:x() + opticalflow_innov:y() * opticalflow_innov:y()) opticalflow_over_threshold = (opticalflow_xy_innov == 0.0) or (opticalflow_xy_innov > opticalflow_innov_thresh) end -- get rangefinder distance local rngfnd_distance_m = 0 if rangefinder:has_data_orient(rangefinder_rotation) then rngfnd_distance_m = rangefinder:distance_cm_orient(rangefinder_rotation) * 0.01 end local rngfnd_over_threshold = (rngfnd_distance_m == 0) or (rngfnd_distance_m > rangefinder_thresh_dist) -- opticalflow is usable if quality and innovations are good and rangefinder is in range local opticalflow_usable = opticalflow_quality_good and (not opticalflow_over_threshold) and (not rngfnd_over_threshold) -- automatic selection logic -- -- GPS vs opticalflow vote. "-1" to move towards GPS, "+1" to move to Non-GPS if (not gps_over_threshold) or (gps_usable and not opticalflow_usable) then -- vote for GPS if GPS accuracy good OR GPS is usable and opticalflow is unusable gps_vs_opticalflow_vote = math.max(gps_vs_opticalflow_vote - 1, -vote_counter_max) elseif opticalflow_usable then -- vote for opticalflow if usable gps_vs_opticalflow_vote = math.min(gps_vs_opticalflow_vote + 1, vote_counter_max) end -- auto source vote collation local auto_source = -1 -- auto source undecided if -1 if gps_vs_opticalflow_vote <= -vote_counter_max then auto_source = 0 -- GPS elseif gps_vs_opticalflow_vote >= vote_counter_max then auto_source = 1 -- opticalflow end -- read source switch position from RCx_FUNCTION = 90 (EKF Source Select) local sw_source_pos = rc_function_source:get_aux_switch_pos() if sw_source_pos ~= sw_source_pos_prev then -- check for changes in source switch position sw_source_pos_prev = sw_source_pos -- record new switch position so we can detect changes auto_switch = false -- disable auto switching of source if source_prev ~= sw_source_pos then -- check if switch position does not match source (there is a one-to-one mapping of switch to source) source_prev = sw_source_pos -- record what source should now be (changed by ArduPilot vehicle code) gcs:send_text(0, "Pilot switched to Source " .. string.format("%d", source_prev+1)) else gcs:send_text(0, "Pilot switched but already Source " .. string.format("%d", source_prev+1)) end play_source_tune(source_prev) -- alert user of source whether changed or not end -- if auto switch exists then read auto source switch position from RCx_FUNCTION = 300 (Scripting1) if rc_function_auto then local sw_auto_pos = rc_function_auto:get_aux_switch_pos() if sw_auto_pos ~= sw_auto_pos_prev then -- check for changes in source auto switch position sw_auto_pos_prev = sw_auto_pos -- record new switch position so we can detect changes if sw_auto_pos == 0 then -- pilot has pulled switch low auto_switch = false -- disable auto switching of source if sw_source_pos ~= source_prev then -- check if source will change source_prev = sw_source_pos -- record pilot's selected source ahrs:set_posvelyaw_source_set(source_prev) -- switch to pilot's selected source gcs:send_text(0, "Auto source disabled, switched to Source " .. string.format("%d", source_prev+1)) else gcs:send_text(0, "Auto source disabled, already Source " .. string.format("%d", source_prev+1)) end elseif sw_auto_pos == 2 then -- pilot has pulled switch high auto_switch = true -- enable auto switching of source if auto_source < 0 then gcs:send_text(0, "Auto source enabled, undecided, Source " .. string.format("%d", source_prev+1)) elseif auto_source ~= source_prev then -- check if source will change source_prev = auto_source -- record pilot's selected source ahrs:set_posvelyaw_source_set(source_prev) -- switch to pilot's selected source gcs:send_text(0, "Auto source enabled, switched to Source " .. string.format("%d", source_prev+1)) else gcs:send_text(0, "Auto source enabled, already Source " .. string.format("%d", source_prev+1)) end end play_source_tune(source_prev) end end -- auto switching if auto_switch and (auto_source >= 0) and (auto_source ~= source_prev) then source_prev = auto_source -- record selected source ahrs:set_posvelyaw_source_set(source_prev) -- switch to pilot's selected source gcs:send_text(0, "Auto switched to Source " .. string.format("%d", source_prev+1)) play_source_tune(source_prev) end return update, 100 end return update()