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AP_Scripting: script for idle control (gas helicopters)
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allows manual and/or automatic engine rpm control during ground idling

fix for conversion to float

rename fix
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@Ferruccio1984 @bnsgeyer
Ferruccio1984 authored and bnsgeyer committed Jan 10, 2024
1 parent 416a41e commit 8bfd8f2
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212 changes: 212 additions & 0 deletions libraries/AP_Scripting/applets/Heli_idle_control.lua
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-- idle_control.lua: a closed loop control throttle control while on ground idle (trad-heli)

local PARAM_TABLE_KEY = 73
local PARAM_TABLE_PREFIX = 'IDLE_'
assert(param:add_table(PARAM_TABLE_KEY, PARAM_TABLE_PREFIX, 30), 'could not add param table')

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

-- parameters for idle control

IDLE_GAIN_I = bind_add_param('GAIN_I', 1, 0.05)
IDLE_GAIN_P = bind_add_param('GAIN_P', 2, 0.25)
IDLE_GAIN_MAX = bind_add_param('GAIN_MAX', 3, 1)
IDLE_MAX = bind_add_param('MAX', 4, 17)
IDLE_RANGE = bind_add_param('RANGE', 5, 300)
IDLE_SETPOINT = bind_add_param('SETPOINT', 6, 600)
IDLE_RPM_ENABLE = bind_add_param('RPM_ENABLE', 7, 0)

-- internal variables

local thr_out = nil
local idle_control_active = false
local idle_control_active_last = false
local last_scaled_output = nil
local idle_default = nil
local ramp_up_complete = false
local idle_adjusted = false
local last_idc_time = nil
local time_now = nil
local pv = nil
local thr_ctl = nil
local thr_out_last = nil
local pot_input = rc:find_channel_for_option(301)
local switch_rsc = rc:find_channel_for_option(32)
local rsc_output = SRV_Channels:find_channel(31)
local SERVO_MAX = Parameter('SERVO' .. (rsc_output+1) .. '_MAX')
local SERVO_MIN = Parameter('SERVO' .. (rsc_output+1) .. '_MIN')
local SERVO_REV = Parameter('SERVO' .. (rsc_output+1) .. '_REVERSED')
local servo_range = SERVO_MAX:get() - SERVO_MIN:get()
local H_RSC_IDLE = Parameter('H_RSC_IDLE')
local H_RSC_RUNUP_TIME = Parameter('H_RSC_RUNUP_TIME')

-- map function

function map(x, in_min, in_max, out_min, out_max)
return out_min + (x - in_min)*(out_max - out_min)/(in_max - in_min)
end

-- constrain function

local function constrain(v, vmin, vmax)
if v < vmin then
v = vmin
end
if v > vmax then
v = vmax
end
return v
end

-- PI controller function
local function PI_controller(kP,kI,iMax,min,max)

local self = {}

local _kP = kP
local _kI = kI
local _iMax = iMax
local _min = min
local _max = max
local _last_t = nil
local _I = 0
local _total = 0
local _counter = 0

function self.update(target, current)
local now = millis()
if not _last_t then
_last_t = now
end
local dt = (now - _last_t):tofloat()*0.001
_last_t = now
local err = target - current
_counter = _counter + 1
local P = _kP:get() * err
if ((_total < _max and _total > _min) or (_total >= _max and err < 0) or (_total <= _min and err > 0)) then
_I = _I + _kI:get() * err * dt
end
if _iMax:get() > 0 then
_I = constrain(_I, -_iMax:get(), iMax:get())
end
local ret = P + _I
_total = ret
return ret
end

function self.reset(integrator)
_I = integrator
end

return self
end

local thr_PI = PI_controller(IDLE_GAIN_P, IDLE_GAIN_I, IDLE_GAIN_MAX, 0, 1)

-- main update function

function update()

local armed = arming:is_armed()

-- aux potentiometer for manual adjusting of idle

local pot_pos = pot_input:norm_input()
local thr_man = map(pot_pos,-1,1,0,1)

if armed == false then
idle_default = H_RSC_IDLE:get()
idle_control_active = false
ramp_up_complete = false
idle_adjusted = false
thr_PI.reset(0)
else
if switch_rsc:get_aux_switch_pos() == 0 and vehicle:get_likely_flying() == false then
if H_RSC_IDLE:get()~= idle_default then
H_RSC_IDLE:set(idle_default)
gcs:send_text(5, "H_RSC_IDLE set to:".. tostring(H_RSC_IDLE:get()))
end
if IDLE_RPM_ENABLE:get() == 0 then
ramp_up_complete = false
idle_adjusted = false
thr_out = H_RSC_IDLE:get() + thr_man*(IDLE_MAX:get() - H_RSC_IDLE:get())
else
if thr_man == 0 then
idle_control_active = false
if idle_control_active_last ~= idle_control_active then
gcs:send_text(5, "idle control: OFF")
end
thr_out = H_RSC_IDLE:get()
thr_ctl = 0
thr_PI.reset(0)
else
local rpm_current = RPM:get_rpm((IDLE_RPM_ENABLE:get())-1)
ramp_up_complete = false
idle_adjusted = false
if rpm_current < (IDLE_SETPOINT:get() - IDLE_RANGE:get()) then
thr_out = H_RSC_IDLE:get() + thr_man*(IDLE_MAX:get() - H_RSC_IDLE:get())
thr_out_last = thr_out
elseif rpm_current > (IDLE_SETPOINT:get() + IDLE_RANGE:get()) then
thr_out = H_RSC_IDLE:get()
thr_out_last = thr_out
else
-- throttle output set from the PI controller
pv = rpm_current/(IDLE_SETPOINT:get())
thr_ctl = thr_PI.update(1, pv)
thr_ctl = constrain(thr_ctl,0,1)
thr_out = H_RSC_IDLE:get() + thr_ctl*(IDLE_MAX:get() - H_RSC_IDLE:get())
if thr_out_last == nil then
thr_out_last = 0
end
thr_out = constrain(thr_out, thr_out_last-0.05, thr_out_last+0.05)
thr_out_last = thr_out
idle_control_active = true
end
if idle_control_active_last ~= idle_control_active then
gcs:send_text(5, "idle control: ON")
end
end
end
last_idc_time = millis()
last_scaled_output = thr_out/100
if SERVO_REV:get() == 0 then
SRV_Channels:set_output_pwm_chan_timeout(rsc_output, math.floor((last_scaled_output*servo_range)+SERVO_MIN:get()), 150)
else
SRV_Channels:set_output_pwm_chan_timeout(rsc_output, math.floor(SERVO_MAX:get()-(last_scaled_output*servo_range)), 150)
end
else
-- motor interlock disabled, armed state, flight
idle_control_active = false
if idle_control_active_last ~= idle_control_active then
gcs:send_text(5, "idle control: deactivated")
end
if ramp_up_complete ~= true then
time_now = millis()
if ((time_now-last_idc_time):tofloat()*0.001) < H_RSC_RUNUP_TIME:get() then
if idle_adjusted ~= true then
H_RSC_IDLE:set(last_scaled_output*100)
idle_adjusted = true
gcs:send_text(5, "H_RSC_IDLE updated for ramp up:".. tostring(H_RSC_IDLE:get()))
end
else
if H_RSC_IDLE:get()~= idle_default then
H_RSC_IDLE:set(idle_default)
gcs:send_text(5, "H_RSC_IDLE default restored:".. tostring(H_RSC_IDLE:get()))
end
ramp_up_complete = true
end
end
end
-- update notify variable
idle_control_active_last = idle_control_active
end

return update, 100 -- 10Hz rate
end

gcs:send_text(5, "idle_control_running")

return update()
17 changes: 17 additions & 0 deletions libraries/AP_Scripting/applets/Heli_idle_control.md
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# Idle Control

Allows manual or automatic rpm control for heli while on ground idle condition

# Parameters

IDLE_GAIN_I = integrative gain of the controller
IDLE_GAIN_P = proportional gain of the controller
IDLE_GAIN_MAX = IMAX for integrative
IDLE_MAX = maximum throttle position, shall be set low enough to prevent clutch engagement/slipping or lower than first point of throttle curve
IDLE_RANGE = rpm range of operation for the idle control
IDLE_SETPOINT = desired rpm setpoint
IDLE_RPM_ENABLE = 0 for manual throttle control // 1 for RPM1 targeting // 2 for RPM2 targeting

# How To Use

set RCx_OPTION to 301 to enable idle control from an auxiliary potentiometer

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