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#!/usr/bin/python3
import os
import sys
import time
import matplotlib.pyplot as plt
from simple_pid import PID
class WaterBoiler:
"""
Simple simulation of a water boiler which can heat up water
and where the heat dissipates slowly over time
"""
def __init__(self):
self.water_temp = 20
def update(self, boiler_power, dt):
if boiler_power > 0:
# Boiler can only produce heat, not cold
self.water_temp += 1 * boiler_power * dt
# Some heat dissipation
self.water_temp -= 0.02 * dt
return self.water_temp
if __name__ == '__main__':
boiler = WaterBoiler()
water_temp = boiler.water_temp
pid = PID(5, 0.01, 0.1, setpoint=water_temp)
pid.output_limits = (0, 100)
start_time = time.time()
last_time = start_time
# Keep track of values for plotting
setpoint, y, x = [], [], []
while time.time() - start_time < 10:
current_time = time.time()
dt = current_time - last_time
power = pid(water_temp)
water_temp = boiler.update(power, dt)
x += [current_time - start_time]
y += [water_temp]
setpoint += [pid.setpoint]
if current_time - start_time > 1:
pid.setpoint = 100
last_time = current_time
plt.plot(x, y, label='measured')
plt.plot(x, setpoint, label='target')
plt.xlabel('time')
plt.ylabel('temperature')
plt.legend()
if os.getenv('NO_DISPLAY'):
# If run in CI the plot is saved to file instead of shown to the user
plt.savefig(f"result-py{'.'.join([str(x) for x in sys.version_info[:2]])}.png")
else:
plt.show()
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