everyone and Professor John
We are using gekko to do MPC on tclab simulation model. We try to emulate the situation that on site the actuator deviates from MV calculated by gekko because of the problems of actuator.
If the deviation is in the fixed pattern, for example a quite big constant deviation happens for a long time and may come back then work well for a long time. We can deal with it by extra logic to detect deviation and add the deviation value to the mv calculated by gekko.
one day, I noticed that there could be meas for MV when fstatus = 1. So I gave it a try. I hope gekko could deal with the deviation by itself. for example, if mv from gekko is 10 and the measurement is 5 and the pattern continues, gekko may spit out a higher MV value than 10, for example 15 and measurement is 10.
In the simulation, when I set MV's fstatus=1, the MV's curve becomes to :

q1a is the q1 with manual deviation. In the above pic, q1a == q1. It looks like gekko takes one more step thinking about the MV's effect.
In the below pic, there are two times range, one with "q1a == q1+20" and the other with "q1a == q1 -20". q1a's value is fed to tclab and mv(q1)'s meas.

I do not understand why the q1 calculated by gekko is going up or going down when meas deviates despite the t1 is going far away from sp.
Edit: Example Code
See the screen shot below from "normal" HMI. The sluggish MV disappeared, so it maybe caused by bug in my code. But the up-going or down-going could still be seen.
See my code below:
from random import random
from random import randrange
import tclab
from tclab import labtime
from tclab import TCLabModel
import numpy as np
import time
import matplotlib.pyplot as plt
from gekko import GEKKO
import json
from tclab import TCLabModel
make_mp4 = True
if make_mp4:
import imageio # required to make animation
import os
try:
os.mkdir('./figures')
except:
pass
class tclab_heaterpipe():
def __init__(self,d1,d2,model):
if(d1 >= 1 and d2 >=1):
self.delay_q1_step = int(d1)
self.delay_q2_step = int(d2)
self.q1_buffer = [0] * self.delay_q1_step
self.q2_buffer = [0] * self.delay_q2_step
self.m = model
else:
self.delay_q1_step =0
self.delay_q2_step =0
return
def Q1_delay(self,q1):
if(self.delay_q1_step == 0):
self.m.Q1(q1)
self.q1_buffer.insert(0,q1)
self.m.Q1(self.q1_buffer.pop())
def Q2_delay(self,q2):
if(self.delay_q2_step == 0):
self.m.Q1(q2)
self.q2_buffer.insert(0,q2)
self.m.Q2(self.q2_buffer.pop())
# Connect to Arduino
connected = False
theta1 = 1
theta2 = 1
T = tclab.setup(connected)
a = T()
tclab_delay = tclab_heaterpipe(theta1,theta2,a)
# Turn LED on
print('LED On')
a.LED(100)
# Simulate a time delay
# Run time in minutes
run_time = 80.0
# Number of cycles
loops = int(60.0*run_time)
# Temperature (K)
t1sp = 45.0
t2sp = 35.0
#########################################################
# Initialize Model
#########################################################
# use remote=True for MacOS
m = GEKKO(name='tclab-mpc',remote=False)
m.time = np.linspace(0,400,41)
step = 10
T1 = np.ones(int(loops/step)+1) * a.T1 # temperature (degC)
T2 = np.ones(int(loops/step)+1) * a.T2 # temperature (degC)
Tsp1 = np.ones(int(loops/step)+1) * t1sp # set point (degC)
Tsp2 = np.ones(int(loops/step)+1) * t2sp # set point (degC)
# heater values
Q1s = np.ones(int(loops/step)+1) * 0.0
Q2s = np.ones(int(loops/step)+1) * 0.0
# Parameters
Q1_ss = m.Param(value=0)
TC1_ss = m.Param(value=a.T1)
Q2_ss = m.Param(value=0)
TC2_ss = m.Param(value=a.T2)
Kp1 = m.Param(value= 0.7)
tau1 = m.Param(value=160.0)
Kp2 = m.Param(value=0.05)
tau2 = m.Param(value=160.0)
Kp3= m.Param(value=0.05)
tau3 = m.Param(value=160.0)
Kp4 = m.Param(value=0.4)
tau4 = m.Param(value=200.0)
sp1 = m.Param(value=a.T1)
sp2 = m.Param(value=a.T2)
# Manipulated variable
Q1 = m.MV(value=0, name='q1')
Q1.STATUS = 1 # use to control temperature
Q1.FSTATUS = 1 # no feedback measurement
Q1.LOWER = 0.0
Q1.UPPER = 100.0
Q1.DMAX = 10.0
Q1.DCOST = 5.0
Q2 = m.MV(value=0, name='q2')
Q2.STATUS = 1 # use to control temperature
Q2.FSTATUS = 1 # no feedback measurement
Q2.LOWER = 0.0
Q2.UPPER = 100.0
Q2.DMAX = 10.0
Q2.DCOST = 5.0
# Controlled variable
TC1 = m.CV(value=a.T1, name='tc1')
TC1.STATUS = 1 # minimize error with setpoint range
TC1.FSTATUS = 1 # receive measurement
TC1.TR_INIT = 2 # reference trajectory
# TC1.COST = 0.1
TC1.WSPHI = 20
TC1.WSPLO = 20
TC1.TAU = 50 # time constant for response
#TC1.TR_OPEN = 3
TC2 = m.CV(value=a.T2, name='tc2')
TC2.STATUS = 1 # minimize error with setpoint range
TC2.FSTATUS = 1 # receive measurement
TC2.TR_INIT = 2 # reference trajectory
# TC2.COST = 0.1
TC2.WSPHI = 20
TC2.WSPLO = 20
TC2.TAU = 30 # time constant for response
#kTC2.TR_OPEN = 3
# 添加延时
Q1d=m.Var()
m.delay(Q1, Q1d, theta1)
Q2d=m.Var()
m.delay(Q2, Q2d, theta2)
# Equation
#m.Equation(tau1 * TC1.dt() + (TC1 - TC1_ss) == Kp1 * (Q1d - Q1_ss))
# m.Equation(tau2 * TC2.dt() + (TC2 - TC2_ss) == Kp2 * (Q1d - Q1_ss))
# m.Equation(tau3 * TC1.dt() + (TC1 - TC1_ss) == Kp3 * (Q2d - Q2_ss))
# m.Equation(tau2 * TC2.dt() + (TC2 - TC2_ss) == Kp4 * (Q2d - Q2_ss))
m.Equation(0.5 * (tau1 * TC1.dt() + (TC1 - TC1_ss) + tau3 * TC1.dt() + (TC1 - TC1_ss)) == Kp1 * (Q1d - Q1_ss) + Kp3 * (Q2d -Q2_ss))
m.Equation(0.5 * (tau2 * TC2.dt() + (TC2 - TC2_ss) + tau4 * TC2.dt() + (TC2 - TC2_ss)) == Kp4 * (Q2d - Q2_ss) + Kp2 * (Q1d - Q1_ss))
# Steady-state initializations
m.options.IMODE = 1
m.options.SOLVER = 1 # 1=APOPT, 3=IPOPT
m.solve()
sp1.VALUE = 45
sp2.VALUE = 35
# Global Options
m.options.IMODE = 6 # MPC
m.options.CV_TYPE = 3 # Objective type
m.options.NODES = 2 # Collocation nodes
m.options.MAX_TIME = 10
m.options.SOLVER = 1 # 1=APOPT, 3=IPOPT
#m.options.CV_WGT_START = 2*theta
#m.options.CV_WGT_SLOPE = theta
# m.options.MV_STEP_HOR = 5
##################################################################
# Create plot
plt.figure()
plt.ion()
plt.show()
# Main Loop
a.Q1(0)
a.Q2(0)
Q2s[0:] = 0
start_time = time.time()
tm = np.linspace(1,loops,int(loops/step)+1)
j=0
try:
time_start = time.time()
labtime_start = labtime.time()
if(not connected):
labtime.set_rate(10)
for i in tclab.clock(loops,adaptive=False):
i = int(i)
if(i == 0):
continue
print("-----------------------")
t_real = time.time() - time_start
t_lab = labtime.time() - labtime_start
print("real time = {0:4.1f} lab time = {1:4.1f} m.time = {1:4.1f}".format(t_real, t_lab,m.time))
#print("real time = {0:4.1f} m.time = {1:4.1f}".format(t_real, m.time))
if(i%step != 0):
continue
j = i/step
j = int(j)
print(j)
T1[j:] = a.T1
T2[j:] = a.T2
tm[j] = i
###############################
### MPC CONTROLLER ###
###############################
TC1.MEAS = T1[j]
TC2.MEAS = T2[j]
print("T1 meas:{0:4.1f} ".format(a.T1))
print("T2 meas:{0:4.1f} ".format(a.T2))
# input setpoint with deadband +/- DT
DT =0.5
TC1.SPHI = Tsp1[j] +DT
TC1.SPLO = Tsp1[j] -DT
TC2.SPHI = Tsp2[j] +DT
TC2.SPLO = Tsp2[j] -DT
try:
# stop model time to solve MPC in cast the solver takes too much time
if(not connected):
labtime.stop()
m.solve(disp=False)
#start model time
if(not connected):
labtime.start()
except Exception as e:
if(not connected):
if(not labtime.running):
labtime.start()
print("sovle's exception:")
print(e)
if(j != 0):
Q1s[j] = Q1s[j-1]
Q2s[j] = Q2s[j-1]
continue
# test for successful solution
if (m.options.APPSTATUS==1):
# retrieve the first Q value
Q1s[j:] = np.ones(len(Q1s)-j) * Q1.NEWVAL
Q2s[j:] = np.ones(len(Q2s)-j) * Q2.NEWVAL
#a.Q1(Q1.NEWVAL)
#a.Q2(Q2.NEWVAL)
print("Q1 applied with delay: {0:4.1f} ".format(Q1.NEWVAL))
print("Q2 applied with delay: {0:4.1f} ".format(Q2.NEWVAL))
with open(m.path+'//results.json') as f:
results = json.load(f)
else:
# not successful, set heater to zero
print("APPSTATUS is not 1,set Q to 0")
#Q1s[j] = 0
#Q2s[j] = 0
if i> 300 and i < 600:
Q1s[j] = Q1s[j] - 20
Q2s[j] = Q2s[j] - 20
if i>= 600:
Q1s[j] = Q1s[j] + 20
Q2s[j] = Q2s[j] + 20
Q1.meas= Q1s[j]
Q2.meas= Q2s[j]
tclab_delay.Q1_delay(Q1s[j])
tclab_delay.Q2_delay(Q2s[j])
print("calc:"+str(Q1s[j]))
print("calc:"+str(Q2s[j]))
#apply disturbance on 50s, 200s,
#if(i == 600):
# Q2s[j] = 100
#if(i == 1400):
# Q2s[j] = 0
#Q2s[j] = 20 - randrange(20)
#Q2s[j:] = np.ones(len(Q2s)-j) * Q2s[j]
#restore Q2 to 0
#if(i == 300):
#Q2s[j:] = 0
#a.Q2(Q2s[j])
#tclab_delay.Q2_delay(Q2s[j])
#take Q2 to FV
#Q2.MEAS = Q2s[j]
if(not connected):
labtime.stop()
# Plot
try:
plt.clf()
ax=plt.subplot(2,1,1)
ax.grid()
plt.plot(tm[0:j],T1[0:j],'ro',markersize=3,label=r'$T_1$')
plt.plot(tm[0:j],Tsp1[0:j],'r-',markersize=3,label=r'$T_1 Setpoint$')
plt.plot(tm[0:j],T2[0:j],'bo',markersize=3,label=r'$T_2$')
plt.plot(tm[0:j],Tsp2[0:j],'b-',markersize=3,label=r'$T_2 Setpoint$')
plt.plot(tm[j]+m.time,results['tc1.bcv'],'r-.',markersize=1,\
label=r'$T_1$ predicted',linewidth=1)
plt.plot(tm[j]+m.time,results['tc2.bcv'],'b-.',markersize=1,\
label=r'$T_2$ predicted',linewidth=1)
plt.plot(tm[j]+m.time,results['tc1.tr_hi'],'k--',\
label=r'$T_1$ trajectory')
plt.plot(tm[j]+m.time,results['tc1.tr_lo'],'k--')
plt.plot(tm[j]+m.time,results['tc2.tr_hi'],'k--',\
label=r'$T_2$ trajectory')
plt.plot(tm[j]+m.time,results['tc2.tr_lo'],'k--')
plt.ylabel('Temperature (degC)')
plt.legend(loc='best')
ax=plt.subplot(2,1,2)
ax.grid()
plt.plot(tm[0:j],Q1s[0:j],'r-',linewidth=3,label=r'$Q_1$')
plt.plot(tm[0:j],Q2s[0:j],'b-',linewidth=3,label=r'$Q_2$')
plt.plot(tm[j]+m.time,Q1.value,'r-.',\
label=r'$Q_1$ plan',linewidth=1)
plt.plot(tm[j]+m.time,Q2.value,'b-.',\
label=r'$Q_2$ plan',linewidth=1)
#plt.plot(tm[0:i],Q2s[0:i],'b:',LineWidth=3,label=r'$Q_2$')
plt.ylabel('Heaters')
plt.xlabel('Time (sec)')
plt.legend(loc='best')
plt.draw()
plt.pause(0.05)
if make_mp4:
filename='./figures/plot_'+str(j+10000)+'.png'
plt.savefig(filename)
except Exception as e:
print(e)
pass
if(not connected):
labtime.start()
# Turn off heaters
a.Q1(0)
a.Q2(0)
print('Shutting down')
input("Press Enter to continue...")
a.close()
# Allow user to end loop with Ctrl-C
except KeyboardInterrupt:
# Disconnect from Arduino
a.Q1(0)
a.Q2(0)
print('Shutting down')
a.close()
if make_mp4:
images = []
iset = 0
for i in range(1,int(loops/step)+1):
filename='./figures/plot_'+str(i+10000)+'.png'
if os.path.exists(filename):
images.append(imageio.imread(filename))
if ((i+1)%350)==0:
imageio.mimsave('results_'+str(iset)+'.mp4', images)
iset += 1
images = []
if images!=[]:
imageio.mimsave('results_'+str(iset)+'.mp4', images)
# 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
Regards Tibalt
