AP_Scripting: Add example based on RTK FS

libraries/AP_Scripting/examples/arming-check_GPS_fix.lua

@@ -0,0 +1,122 @@
+-- This script checks the current GPS RTK fix status. If in Copter Auto mode, it does not allow arming. Any other mode, it will report RTK fix isn't there.
+-- If RTK fix goes in flight during auto mission, it will switch to guided mode to climb to some height.
+
+local MODE_AUTO = 3
+local MODE_LOITER = 5
+local MODE_GUIDED = 4
+
+local guided_climbing_mode = false
+local update_rate_ms = 250
+local sent_rtk_fix_message = false
+local saved_location_height
+local last_message_sent_ms = 0
+
+auth_id = arming:get_aux_auth_id()
+
+PARAM_TABLE_KEY = 122
+PARAM_TABLE_PREFIX = "RTK_FS_"
+
+-- bind a parameter to a variable given
+function bind_param(name)
+    local p = Parameter()
+    assert(p:init(name), string.format('could not find %s parameter', name))
+    return p
+end
+
+-- add a parameter and bind it to a variable
+function bind_add_param(name, idx, default_value)
+    assert(param:add_param(PARAM_TABLE_KEY, idx, name, default_value), string.format('could not add param %s', name))
+    return bind_param(PARAM_TABLE_PREFIX .. name)
+end
+
+-- Setup RTK FS Parameters
+assert(param:add_table(PARAM_TABLE_KEY, PARAM_TABLE_PREFIX, 5), 'could not add RTK_FS param table')
+
+--[[
+  // @Param: RTK_FS_ENABLE
+  // @DisplayName: Enable GPS RTK Failsafe features
+  // @Description: Enable GPS RTK Failsafe features
+  // @Values: 0:Disabled,1:Enabled
+  // @User: Standard
+--]]
+local RTK_FS_ENABLE     = bind_add_param('ENABLE',     1, 0)
+
+--[[
+  // @Param: RTK_FS_HEIGHT
+  // @DisplayName: RTK Failsafe height gain
+  // @Description: Vehicle will gain this many meters in height after RTK fixed status is lost in Auto mode
+  // @Range: 1 5
+  // @User: Standard
+--]]
+local RTK_FS_HEIGHT     = bind_add_param('HEIGHT',    2, 3)
+
+
+function handle_emergency_climb()
+      local current_loc = ahrs:get_location()
+      current_loc:alt(saved_location_height + RTK_FS_HEIGHT:get() * 100)
+      vehicle:set_target_location(current_loc)
+end
+
+function send_message_with_timeout(msg_string, timeout_ms)
+  if (millis() - last_message_sent_ms > timeout_ms) then
+    gcs:send_text(0, msg_string)
+    last_message_sent_ms = millis()
+  end
+end
+
+function update() -- this is the loop which periodically runs
+
+  if RTK_FS_ENABLE:get() == 0 then
+    arming:set_aux_auth_passed(auth_id)
+    return update, update_rate_ms
+  end
+
+  local current_gps_status = gps:status(0)
+  local current_mode = vehicle:get_mode()
+  if not arming:is_armed() then
+    if (current_gps_status ~= gps.GPS_OK_FIX_3D_RTK_FIXED) then
+      -- do not allow arming if vehicle is in auto mode but not RTK fix
+      sent_rtk_fix_message = false
+      if current_mode == MODE_AUTO then
+        arming:set_aux_auth_failed(auth_id, "Waiting for RTK fix")
+      else
+        send_message_with_timeout(string.format("Waiting for RTK fix"), 10000)
+        -- pass check but warn user
+        arming:set_aux_auth_passed(auth_id)
+      end
+    else
+      -- all good with the GPS
+      if sent_rtk_fix_message == false then
+        gcs:send_text(6, string.format("GPS has RTK Fix"))
+        sent_rtk_fix_message = true
+      end
+      arming:set_aux_auth_passed(auth_id)
+    end
+    return update, update_rate_ms
+  end
+
+  if guided_climbing_mode then
+    if (current_mode ~= MODE_GUIDED) then
+      guided_climbing_mode = false
+      gcs:send_text(0, string.format("Mode changed. Exiting RTK failsafe"))
+    else
+      handle_emergency_climb()
+    end
+    return update, update_rate_ms
+  end
+
+  -- armed
+  if current_gps_status ~= gps.GPS_OK_FIX_3D_RTK_FIXED then
+    if current_mode == MODE_LOITER then
+      send_message_with_timeout(string.format("Attention, RTK fix lost"), 5000)
+    elseif current_mode == MODE_AUTO then
+      gcs:send_text(0, string.format("RTK fix lost, mission stopped"))
+      guided_climbing_mode = true
+      vehicle:set_mode(MODE_GUIDED)
+      saved_location_height = ahrs:get_location():alt() -- record height. We don't want to go lower than this height 
+    end
+  end
+  return update, update_rate_ms -- reschedules the loop
+end
+
+return update() -- run immediately before starting to reschedule