PyCNC

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import unittest
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from cnc.pid import *
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from cnc.config import *
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class TestPid(unittest.TestCase):
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    def setUp(self):
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        self._environment_temp = 25
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        # Coefficients below were chosen by an experimental way with a real
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        # hardware: reprap heating bed and extruder.
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        # See ../utils/heater_model_finder.py to find out this coefficients.
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        self._bed_c = 0.0027  # bed cooling coefficient
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        self._bed_h = 0.2522  # bed heating coefficient
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        self._extruder_c = 0.0108  # extruder cooling coefficient
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        self._extruder_h = 3.4070  # extruder heating coefficient
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    def tearDown(self):
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        pass
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    def __simulate(self, target_temp, pid_c, environment_temp, cool, heat):
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        # Simulate heating some hypothetical thing with heater(h is a heat
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        # transfer coefficient, which becomes just a delta temperature each
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        # second) from environment temperature to target_temp. Consider that
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        # there is natural air cooling process with some heat transfer
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        # coefficient c. Heating power is controlled by PID.
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        pid = Pid(target_temp, pid_c, 0)
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        temperature = environment_temp
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        heater_power = 0
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        fixed_at = None
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        zeros_counter = 0
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        total_counter = 0
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        iter_pes_s = 2  # step is 0.5s
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        j = 1
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        for k in range(1, 20 * 60 * iter_pes_s + 1):  # simulate for 20 minutes
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            j = k / float(iter_pes_s)
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            # natural cooling
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            temperature -= ((temperature - environment_temp) * cool
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                            / float(iter_pes_s))
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            # heating
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            temperature += heat * heater_power / float(iter_pes_s)
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            heater_power = pid.update(temperature, j)
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            if fixed_at is None:
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                if pid.is_fixed():
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                    fixed_at = j
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            else:
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                self.assertLess(abs(temperature - target_temp),
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                                pid.FIX_ACCURACY * target_temp * 5.0,
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                                msg="PID failed to control temperature "
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                                "{}/{} {}".format(temperature, target_temp, j))
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            if heater_power == 0.0:
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                zeros_counter += 1
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            total_counter += 1
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        self.assertLess(abs(temperature - target_temp),
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                        pid.FIX_ACCURACY * target_temp,
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                        msg="PID failed to control temperature "
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                        "{}/{} {}".format(temperature, target_temp, j))
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        self.assertLess(zeros_counter, total_counter * 0.05,
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                        msg="PID turns on/off, instead of fine control")
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        self.assertLess(fixed_at, 900,
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                        msg="failed to heat in 15 minutes, final temperature "
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                            "{}/{}".format(temperature, target_temp))
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    def test_simple(self):
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        pid = Pid(50, EXTRUDER_PID, 0)
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        self.assertEqual(0, pid.update(100, 1))
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        self.assertEqual(1, pid.update(0, 2))
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        pid = Pid(50, BED_PID, 0)
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        self.assertEqual(0, pid.update(100, 1))
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        self.assertEqual(1, pid.update(0, 2))
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    def test_extruder(self):
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        # check if extruder typical temperatures can be reached in simulation
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        for target in range(150, 251, 10):
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            self.__simulate(target, EXTRUDER_PID, self._environment_temp,
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                            self._extruder_c, self._extruder_h)
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    def test_bed(self):
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        # check if bed typical temperatures can be reached in simulation
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        for target in range(50, 101, 10):
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            self.__simulate(target, BED_PID, self._environment_temp,
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                            self._bed_c, self._bed_h)
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if __name__ == '__main__':
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    unittest.main()
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