kilnController/oven.py

import threading,time,random,datetime,logging,json
import config

log = logging.getLogger(__name__)

try:
    from max31855 import MAX31855, MAX31855Error
    sensor_available = True
except ImportError:
    log.warning("Could not initialize temperature sensor, using dummy values!")
    sensor_available = False

try:
    import RPi.GPIO as GPIO
    GPIO.setmode(GPIO.BCM)
    GPIO.setwarnings(False)
    GPIO.setup(config.gpio_heat, GPIO.OUT)
    GPIO.setup(config.gpio_cool, GPIO.OUT)
    GPIO.setup(config.gpio_air, GPIO.OUT)
    GPIO.setup(config.gpio_door, GPIO.IN, pull_up_down=GPIO.PUD_UP)

    gpio_available = True
except ImportError:
    log.warning("Could not initialize GPIOs, oven operation will only be simulated!")
    gpio_available = False

class Oven (threading.Thread):
    STATE_IDLE     = "IDLE"
    STATE_RUNNING  = "RUNNING"

    def __init__(self,simulate = False,time_step=0.5):
        threading.Thread.__init__(self)
        self.daemon = True
        self.simulate = simulate
        self.time_step = time_step
        self.reset()
        if simulate:
            self.temp_sensor = TempSensorSimulate(self,0.5,self.time_step)
        if sensor_available:
            self.temp_sensor = TempSensorReal(self.time_step)
        else:
            self.temp_sensor = TempSensorSimulate(self,self.time_step,self.time_step)
        self.temp_sensor.start()
        self.start()

    def reset(self):
        self.profile = None
        self.start_time = 0
        self.runtime = 0
        self.totaltime = 0
        self.target = 0
        self.door = self.get_door_state()
        self.state = Oven.STATE_IDLE
        self.set_heat(False)
        self.set_cool(False)
        self.set_air(False)
        self.pid = PID(ki=config.pid_ki,kd=config.pid_kd,kp=config.pid_kp)

    def run_profile(self, profile):
        log.info("Running profile %s"%profile.name)
        self.profile = profile
        self.totaltime = profile.get_duration()
        self.state = Oven.STATE_RUNNING
        self.start_time = datetime.datetime.now()
        log.info("Starting")

    def abort_run(self):
        self.reset()

    def run(self):
        while True:
            self.door = self.get_door_state()

            if self.state == Oven.STATE_RUNNING:
                if self.simulate:
                    self.runtime += 0.5
                else:
                    self.runtime = (datetime.datetime.now() - self.start_time).total_seconds()
                log.info("running at %.1f deg C (Target: %.1f) , heat %.2f, cool %.2f, air %.2f, door %s (%.1fs/%.0f)"%(self.temp_sensor.temperature,self.target,self.heat,self.cool,self.air,self.door,self.runtime,self.totaltime))
                self.target = self.profile.get_target_temperature(self.runtime)
                pid = self.pid.compute(self.target, self.temp_sensor.temperature)

                log.info("pid: %.3f"%pid)

                self.set_cool(pid <= -1)
                self.set_heat(pid > 0)

                #if self.profile.is_rising(self.runtime):
                #    self.set_cool(False)
                #    self.set_heat(self.temp_sensor.temperature < self.target)
                #else:
                #    self.set_heat(False)
                #    self.set_cool(self.temp_sensor.temperature > self.target)

                if self.temp_sensor.temperature>200:
                    self.set_air(False)
                elif self.temp_sensor.temperature<180:
                    self.set_air(True)

                if self.runtime >= self.totaltime:
                    self.reset()

            time.sleep(self.time_step)
    

    def set_heat(self,value):
        if value:
            self.heat = 1.0
            if gpio_available:
                GPIO.output(config.gpio_heat, GPIO.LOW)
        else:
            self.heat = 0.0
            if gpio_available:
                GPIO.output(config.gpio_heat, GPIO.HIGH)

    def set_cool(self,value):
        if value:
            self.cool = 1.0
            if gpio_available:
                GPIO.output(config.gpio_cool, GPIO.LOW)
        else:
            self.cool = 0.0
            if gpio_available:
                GPIO.output(config.gpio_cool, GPIO.HIGH)

    def set_air(self,value):
        if value:
            self.air = 1.0
            if gpio_available:
                GPIO.output(config.gpio_air, GPIO.LOW)
        else:
            self.air = 0.0
            if gpio_available:
                GPIO.output(config.gpio_air, GPIO.HIGH)

    def get_state(self):
        state = {
            'runtime': self.runtime,
            'temperature': self.temp_sensor.temperature,
            'target': self.target,
            'state': self.state,
            'heat': self.heat,
            'cool': self.cool,
            'air' : self.air,
            'totaltime': self.totaltime,
            'door': self.door
        }
        return state

    def get_door_state(self):
        if gpio_available:
            return "OPEN" if GPIO.input(config.gpio_door) else "CLOSED"
        else:
            return "UNKNOWN"


class TempSensor(threading.Thread):
    def __init__(self,time_step):
        threading.Thread.__init__(self)
        self.daemon = True
        self.temperature = 0
        self.time_step = time_step
        
class TempSensorReal(TempSensor):
    def __init__(self,time_step):
        TempSensor.__init__(self,time_step)
        self.thermocouple = MAX31855(config.gpio_sensor_cs, 
                                     config.gpio_sensor_clock, 
                                     config.gpio_sensor_data, 
                                     "c"
                                    )

    def run(self):
        while True:
            self.temperature = self.thermocouple.get()
            time.sleep(self.time_step)

class TempSensorSimulate(TempSensor):
    def __init__(self,oven,time_step,sleep_time):
        TempSensor.__init__(self,time_step)
        self.oven = oven
        self.sleep_time = sleep_time

    def run(self):
        t_env      = config.sim_t_env
        c_heat     = config.sim_c_heat
        c_oven     = config.sim_c_oven
        p_heat     = config.sim_p_heat
        R_o_nocool = config.sim_R_o_nocool
        R_o_cool   = config.sim_R_o_cool
        R_ho_noair = config.sim_R_ho_noair
        R_ho_air = config.sim_R_ho_air

        t = t_env #deg C  temp in oven
        t_h = t #deg C temp of heat element
        while True:
            #heating energy
            Q_h = p_heat * self.time_step * self.oven.heat

            #temperature change of heat element by heating
            t_h += Q_h / c_heat

            if self.oven.air:
                R_ho = R_ho_air
            else:
                R_ho = R_ho_noair

            #energy flux heat_el -> oven
            p_ho = (t_h - t) / R_ho

            #temperature change of oven and heat el
            t   += p_ho *self.time_step / c_oven
            t_h -= p_ho *self.time_step / c_heat


            #energy flux oven -> env
            if self.oven.cool:
                p_env = (t - t_env) / R_o_cool
            else:
                p_env = (t - t_env) / R_o_nocool

            #temperature change of oven by cooling to env
            t -= p_env *self.time_step / c_oven
            log.debug("energy sim: -> %dW heater: %.0f -> %dW oven: %.0f -> %dW env"%(int(p_heat * self.oven.heat),t_h,int(p_ho),t,int(p_env)))
            self.temperature = t

            time.sleep(self.sleep_time)

class Profile():
    def __init__(self,json_data):
        obj = json.loads(json_data)
        self.name = obj["name"]
        self.data = sorted(obj["data"])

    def get_duration(self):
        return max([t for (t,x) in self.data])

    def get_surrounding_points(self,time):
        if time > self.get_duration():
            return (None,None)

        prev_point = None
        next_point = None

        for i in range(len(self.data)):
            if time < self.data[i][0]:
                prev_point = self.data[i-1]
                next_point = self.data[i]
                break

        return (prev_point,next_point)

    def is_rising(self,time):
        (prev_point,next_point) = self.get_surrounding_points(time)
        if prev_point and next_point:
            return prev_point[1] < next_point[1]
        else:
            return False

    def get_target_temperature(self,time):
        if time > self.get_duration():
            return 0

        (prev_point,next_point) = self.get_surrounding_points(time)

        incl = float(next_point[1] - prev_point[1]) / float(next_point[0] - prev_point[0])
        temp = prev_point[1] + (time - prev_point[0]) * incl
        return temp

class PID():
    def __init__(self,ki=1,kp=1,kd=1):
        self.ki = ki
        self.kp = kp
        self.kd = kd
        self.lastNow = datetime.datetime.now()
        self.iterm = 0
        self.lastErr = 0

    def compute(self,setpoint,ispoint):
        now = datetime.datetime.now()
        timeDelta = (now - self.lastNow).total_seconds()

        error = float(setpoint - ispoint)
        self.iterm += (error * timeDelta * self.ki)
        self.iterm=sorted([-1,self.iterm,1])[1]
        dErr = (error - self.lastErr) / timeDelta

        output = self.kp * error + self.iterm + self.kd * dErr
        output = sorted([-1,output,1])[1]
        self.lastErr = error
        self.lastNow = now

        return output