Gekko only needs one definition of the model and options. The rest can go inside the loop.
point = [40,20,10,35]
traject= [1,30,60,100]
# Controlled Variable
v = m.CV(value=0)
v.STATUS = 1 # add the SP to the objective
v.TAU = 5 # time constant of trajectory
# Process model
m.Equation(mass*v.dt() == -v*b + K*b*p)
m.options.CV_TYPE = 2 # squared error
m.options.IMODE = 6 # control
for i in range (len(point)):
v.SP = point[i] # set point
v.TR_INIT = traject[i] # set point trajectory
m.solve(disp=False)
Here is a more complete example that gets data from an Arduino. Use TCLabModel to use the Arduino simulator.
import tclab
import numpy as np
import time
import matplotlib.pyplot as plt
from gekko import GEKKO
# Connect to Arduino
a = tclab.TCLabModel()
# Get Version
print(a.version)
# Turn LED on
print('LED On')
a.LED(100)
# Run time in minutes
run_time = 5.0
# Number of cycles
loops = int(60.0*run_time)
tm = np.zeros(loops)
# Temperature (K)
T1 = np.ones(loops) * a.T1 # temperature (degC)
Tsp1 = np.ones(loops) * 30.0 # set point (degC)
# Set point changes
Tsp1[100:] = 40.0
Tsp1[200:] = 35.0
T2 = np.ones(loops) * a.T2 # temperature (degC)
Tsp2 = np.ones(loops) * 23.0 # set point (degC)
# heater values
Q1s = np.ones(loops) * 0.0
Q2s = np.ones(loops) * 0.0
#########################################################
# Initialize Model
#########################################################
# use remote=True for MacOS
m = GEKKO(name='tclab-mpc',remote=False)
# 30 second time horizon
m.time = np.linspace(0,30,31)
# Parameters
Q1_ss = m.Param(value=0)
TC1_ss = m.Param(value=23)
Kp = m.Param(value=0.4)
tau = m.Param(value=160.0)
# Manipulated variable
Q1 = m.MV(value=0)
Q1.STATUS = 1 # use to control temperature
Q1.FSTATUS = 0 # no feedback measurement
Q1.LOWER = 0.0
Q1.UPPER = 100.0
Q1.DMAX = 50.0
Q1.COST = 0.0
Q1.DCOST = 1.0e-4
# Controlled variable
TC1 = m.CV(value=TC1_ss.value)
TC1.STATUS = 1 # minimize error with setpoint range
TC1.FSTATUS = 1 # receive measurement
TC1.TR_INIT = 2 # reference trajectory
TC1.TAU = 10 # time constant for response
# Equation
m.Equation(tau * TC1.dt() + (TC1-TC1_ss) == Kp * (Q1-Q1_ss))
# Global Options
m.options.IMODE = 6 # MPC
m.options.CV_TYPE = 1 # Objective type
m.options.NODES = 3 # Collocation nodes
m.options.SOLVER = 1 # 1=APOPT, 3=IPOPT
##################################################################
# Create plot
plt.figure()
plt.ion()
plt.show()
# Main Loop
start_time = time.time()
prev_time = start_time
try:
for i in range(1,loops):
# Sleep time
sleep_max = 1.0
sleep = sleep_max - (time.time() - prev_time)
if sleep>=0.01:
time.sleep(sleep)
else:
time.sleep(0.01)
# Record time and change in time
t = time.time()
dt = t - prev_time
prev_time = t
tm[i] = t - start_time
# Read temperatures in Kelvin
T1[i] = a.T1
T2[i] = a.T2
###############################
### MPC CONTROLLER ###
###############################
TC1.MEAS = T1[i]
# input setpoint with deadband +/- DT
DT = 0.1
TC1.SPHI = Tsp1[i] + DT
TC1.SPLO = Tsp1[i] - DT
# solve MPC
m.solve(disp=False)
# test for successful solution
if (m.options.APPSTATUS==1):
# retrieve the first Q value
Q1s[i] = Q1.NEWVAL
else:
# not successful, set heater to zero
Q1s[i] = 0
# Write output (0-100)
a.Q1(Q1s[i])
a.Q2(Q2s[i])
# Plot
plt.clf()
ax=plt.subplot(2,1,1)
ax.grid()
plt.plot(tm[0:i],T1[0:i],'ro',MarkerSize=3,label=r'$T_1$')
plt.plot(tm[0:i],Tsp1[0:i],'b-',MarkerSize=3,label=r'$T_1 Setpoint$')
plt.ylabel('Temperature (degC)')
plt.legend(loc='best')
ax=plt.subplot(2,1,2)
ax.grid()
plt.plot(tm[0:i],Q1s[0:i],'r-',lw=3,label=r'$Q_1$')
plt.plot(tm[0:i],Q2s[0:i],'b:',lw=3,label=r'$Q_2$')
plt.ylabel('Heaters')
plt.xlabel('Time (sec)')
plt.legend(loc='best')
plt.draw()
plt.pause(0.05)
# Turn off heaters
a.Q1(0)
a.Q2(0)
print('Shutting down')
# Allow user to end loop with Ctrl-C
except KeyboardInterrupt:
# Disconnect from Arduino
a.Q1(0)
a.Q2(0)
print('Shutting down')
a.close()
# Make sure serial connection still closes when there's an error
except:
# Disconnect from Arduino
a.Q1(0)
a.Q2(0)
print('Error: Shutting down')
a.close()
raise
