AP_Scripting: added throttle_kill applet

libraries/AP_Scripting/applets/throttle_kill.lua

@@ -0,0 +1,100 @@
+--[[
+   script to allow for engine kill on turbine engines using an auxilliary function
+--]]
+
+local MAV_SEVERITY = {EMERGENCY=0, ALERT=1, CRITICAL=2, ERROR=3, WARNING=4, NOTICE=5, INFO=6, DEBUG=7}
+
+local PARAM_TABLE_KEY = 102
+local PARAM_TABLE_PREFIX = "THR_"
+
+-- 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 Parameter(PARAM_TABLE_PREFIX .. name)
+end
+
+-- setup quicktune specific parameters
+assert(param:add_table(PARAM_TABLE_KEY, PARAM_TABLE_PREFIX, 5), 'could not add param table')
+
+local PERIOD_MS = 50
+
+--[[
+  // @Param: THR_KILL_FUNC
+  // @DisplayName: AUX function to kill engine
+  // @Description: AUX function to kill engine. This can be activated either with a RCn_OPTION and a R/C switch or with a ground station auxilliary function
+  // @Range: 300 307
+  // @User: Standard
+--]]
+local THR_KILL_FUNC = bind_add_param('KILL_FUNC', 1, 300)
+
+--[[
+  // @Param: THR_KILL_PWM
+  // @DisplayName: PWM on kill active
+  // @Description: PWM on kill active
+  // @Range: 800 2200
+  // @User: Standard
+--]]
+local THR_KILL_PWM = bind_add_param('KILL_PWM', 2, 900)
+
+--[[
+  // @Param: THR_KILL_CHAN
+  // @DisplayName: output channel to change on throttle kill
+  // @Description: output channel to change on throttle kill, a value of zero disables the feature
+  // @Range: 0 32
+  // @User: Standard
+--]]
+local THR_KILL_CHAN = bind_add_param('KILL_CHAN', 3, 0)
+
+--[[
+  // @Param: THR_KILL_VAL
+  // @DisplayName: auxilliary value to kill throttle
+  // @Description: auxilliary value to kill throttle. Set to 2 to kill the throttle when the auxilliary is high. Set to 0 to kill when auxilliary is low
+  // @Range: 0 2
+  // @User: Standard
+--]]
+local THR_KILL_VAL = bind_add_param('KILL_VAL', 4, 2)
+
+--[[
+  // @Param: THR_KILL_DEF
+  // @DisplayName: throttle kill default value
+  // @Description: throttle kill default value. The default auxilliary function position on boot
+  // @Range: 0 2
+  // @User: Standard
+--]]
+local THR_KILL_DEF = bind_add_param('KILL_DEF', 5, 0)
+
+local last_active = false
+
+--[[
+   update the throttle kill from AUX function
+--]]
+local function update_kill()
+   if THR_KILL_CHAN:get() <= 0 then
+      return
+   end
+   local sw_pos = rc:get_aux_cached(THR_KILL_FUNC:get())
+   if not sw_pos then
+      sw_pos = THR_KILL_DEF:get()
+   end
+   if sw_pos == THR_KILL_VAL:get() then
+      SRV_Channels:set_output_pwm_chan_timeout(THR_KILL_CHAN:get()-1, math.floor(THR_KILL_PWM:get()), 2*PERIOD_MS)
+      if not last_active then
+         last_active = true
+         gcs:send_text(MAV_SEVERITY.WARNING, "Engine disabled")
+      end
+   else
+      if last_active then
+         gcs:send_text(MAV_SEVERITY.WARNING, "Engine enabled")
+      end
+      last_active = false
+   end
+end
+
+gcs:send_text(MAV_SEVERITY.INFO, "Engine kill script started")
+
+local function update()
+   update_kill()
+   return update, PERIOD_MS
+end
+
+return update, PERIOD_MS

libraries/AP_Scripting/applets/throttle_kill.md

@@ -0,0 +1,42 @@
+# Throttle Kill Applet
+
+This applet is for fixed wing aircraft to allow a throttle value below
+SERVO3_MIN to be used to kill an engine that uses PWM for engine kill,
+while allowing values below SERVO3_MIN in any mode without the kill
+switch being activated.
+
+It is particularly suited to turbine engines which kill the motor
+using a low throttle input.
+
+# Parameters
+
+The script creates a set of parameters with names starting withg THR_KILL
+
+## THR_KILL_FUNC
+
+This is the auxillary function to use for activating the throttle
+kill. This should be set to a scripting auxillary function such as 300
+
+## THR_KILL_CHAN
+
+This is the output channel to apply the throttle kill to. This is
+normally 3 for SERVO3
+
+## THR_KILL_VAL
+
+This is the auxiallary function value to activate the kill
+switch. This is normally 2 meaning to activate on a high value of the
+auxillary function. If you want it to activate on low values then set
+this to 0.
+
+## THR_KILL_DEF
+
+This is the default auxiallary function value at startup. If you want
+the engine to be killed by default on startup then set this to the
+same value as THR_KILL_VAL
+
+# Usage
+
+After this script is installed and you have setup the above parameters
+then the THR_KILL_CHAN servo output channel will be forced to
+THR_KILL_PWM when the auxillary function is activated.