## Apps.LinearStateSpace History

November 11, 2019, at 01:32 PM by 136.36.211.159 -
Changed lines 13-14 from:
 GEKKO Usage: x,y,u = m.state_space(A,B,C)
Optional arguments: D=None,E=None, discrete=False,dense=False

to:
 GEKKO Usage: x,y,u = m.state_space(A,B,C,D=None)
Other optional arguments: E=None,discrete=False,dense=False

November 11, 2019, at 01:31 PM by 136.36.211.159 -
Changed lines 13-14 from:
 GEKKO Usage: x,y,u = m.state_space(A,B,C,D=None,E=None,                                    discrete=False,dense=False)

to:
 GEKKO Usage: x,y,u = m.state_space(A,B,C)
Optional arguments: D=None,E=None, discrete=False,dense=False

November 11, 2019, at 01:28 PM by 136.36.211.159 -
Changed line 8 from:
 Data: A, B, C, and D matrices

to:
 Data: A, B, C, D, and E matrices

Changed lines 13-14 from:
 GEKKO Usage: x,y,u = m.state_space(A,B,C,D=None)

to:
 GEKKO Usage: x,y,u = m.state_space(A,B,C,D=None,E=None,                                    discrete=False,dense=False)

Changed lines 18-19 from:

$$\dot x = A x + B u$$

to:

$$E\dot x = A x + B u$$

$$E \in \mathbb{R}^{n \, \mathrm{x} \, n}$$

Changed lines 179-183 from:

Also see Discrete State Space and State Space Introduction

to:

Also see:

Changed line 1 from:

(:title State Space Models:)

to:

(:title State Space Model Object:)

Changed line 1 from:

(:title APMonitor and GEKKO State Space Models:)

to:

(:title State Space Models:)

Changed line 179 from:
to:

Also see Discrete State Space and State Space Introduction

Changed lines 1-3 from:

## Linear Model Predictive Control

to:

(:title APMonitor and GEKKO State Space Models:) (:keywords linear, state space, stability, dynamic, multiple input, multiple output, MIMO, model predictive control:) (:description Linear Time Invariant (LTI) state space models are a linear representation of a dynamic system in either discrete or continuous time. Examples show how to use continuous LTI state space models in APMonitor and GEKKO.:) APMonitor Objects
 Type: Object
Data: A, B, C, and D matrices
Inputs: Input (u)
Outputs: States (x), Output (y)
Description: LTI State Space Model
APMonitor Usage: sys = lti
GEKKO Usage: x,y,u = m.state_space(A,B,C,D=None)


Linear Time Invariant (LTI) state space models are a linear representation of a dynamic system in either discrete or continuous time. Putting a model into state space form is the basis for many methods in process dynamics and control analysis. Below is the continuous time form of a model in state space form.

$$\dot x = A x + B u$$

$$y = C x + D u$$

with states x in \mathbb{R}^n and state derivatives \dot x = {dx}/{dt} in \mathbb{R}^n. The notation in \mathbb{R}^n means that x and \dot x are in the set of real-numbered vectors of length n. The other elements are the outputs y in \mathbb{R}^p, the inputs u in \mathbb{R}^m, the state transition matrix A, the input matrix B, and the output matrix C. The remaining matrix D is typically zeros because the inputs do not typically affect the outputs directly. The dimensions of each matrix are shown below with m inputs, n states, and p outputs.

$$A \in \mathbb{R}^{n \, \mathrm{x} \, n}$$ $$B \in \mathbb{R}^{n \, \mathrm{x} \, m}$$ $$C \in \mathbb{R}^{p \, \mathrm{x} \, n}$$ $$D \in \mathbb{R}^{p \, \mathrm{x} \, m}$$

November 17, 2018, at 07:29 AM by 174.148.88.122 -
Changed line 65 from:

to:

#### Example Model Predictive Control in GEKKO

Changed lines 10-12 from:

## Example Model

to:

#### Example Model Predictive Control in GEKKO

(:source lang=python:) import numpy as np from gekko import GEKKO

A = np.array([[-.003, 0.039, 0, -0.322],

              [-0.065, -0.319, 7.74, 0],
[0.020, -0.101, -0.429, 0],
[0, 0, 1, 0]])


B = np.array([[0.01, 1, 2],

              [-0.18, -0.04, 2],
[-1.16, 0.598, 2],
[0, 0, 2]]
)


C = np.array([[1, 0, 0, 0],

              [0, -1, 0, 7.74]])

1. Build GEKKO State Space model

m = GEKKO() x,y,u = m.state_space(A,B,C,D=None)

1. customize names
2. MVs

mv0 = u mv1 = u

1. Feedforward

ff0 = u

1. CVs

cv0 = y cv1 = y

m.time = [0, 0.1, 0.2, 0.4, 1, 1.5, 2, 3, 4] m.options.imode = 6 m.options.nodes = 3

u.lower = -5 u.upper = 5 u.dcost = 1 u.status = 1

u.lower = -5 u.upper = 5 u.dcost = 1 u.status = 1

1. CV tuning
1. tau = first order time constant for trajectories

y.tau = 5 y.tau = 8

1. tr_init = 0 (dead-band)
2. = 1 (first order trajectory)
3. = 2 (first order traj, re-center with each cycle)

y.tr_init = 0 y.tr_init = 0

1. targets (dead-band needs upper and lower values)
2. SPHI = upper set point
3. SPLO = lower set point

y.sphi= -8.5 y.splo= -9.5 y.sphi= 5.4 y.splo= 4.6

y.status = 1 y.status = 1

1. feedforward

u.status = 0 u.value = np.zeros(np.size(m.time)) u.value[3:] = 2.5

m.solve() # (GUI=True)

1. also create a Python plot

import matplotlib.pyplot as plt

plt.subplot(2,1,1) plt.plot(m.time,mv0.value,'r-',label=r'$u_0$ as MV') plt.plot(m.time,mv1.value,'b--',label=r'$u_1$ as MV') plt.plot(m.time,ff0.value,'g:',label=r'$u_2$ as feedforward') plt.subplot(2,1,2) plt.plot(m.time,cv0.value,'r-',label=r'$y_0$') plt.plot(m.time,cv1.value,'b--',label=r'$y_1$') plt.show() (:sourceend:)

Changed line 32 from:
 File *.mpc.txt

to:
 File mpc.txt

Changed line 40 from:
 File *.mpc.a.txt

to:
 File mpc.a.txt

Changed line 47 from:
 File *.mpc.b.txt

to:
 File mpc.b.txt

Changed line 55 from:
 File *.mpc.c.txt

to:
 File mpc.c.txt

Changed line 62 from:
 File *.mpc.d.txt

to:
 File mpc.d.txt

Changed lines 14-19 from:

Model control

  Objects
mpc = lti
End Objects


End Model

to:
 Model control
Objects
mpc = lti
End Objects
End Model

Changed lines 32-38 from:

File *.mpc.txt

  sparse, continuous  ! dense/sparse, continuous/discrete
2      ! m=number of inputs
3      ! n=number of states
3      ! p=number of outputs


End File

to:
 File *.mpc.txt
sparse, continuous  ! dense/sparse, continuous/discrete
2      ! m=number of inputs
3      ! n=number of states
3      ! p=number of outputs
End File

Changed lines 40-45 from:

File *.mpc.a.txt

  1  1  0.9
2  2  0.1
3  3  0.5


End File

to:
 File *.mpc.a.txt
1  1  0.9
2  2  0.1
3  3  0.5
End File

Changed lines 47-53 from:

File *.mpc.b.txt

  1  1  1.0
2  2  1.0
3  1  0.5
3  2  0.5


End File

to:
 File *.mpc.b.txt
1  1  1.0
2  2  1.0
3  1  0.5
3  2  0.5
End File

Changed lines 55-60 from:

File *.mpc.c.txt

  1  1  0.5
2  2  1.0
3  3  2.0


End File

to:
 File *.mpc.c.txt
1  1  0.5
2  2  1.0
3  3  2.0
End File

Changed lines 62-64 from:

File *.mpc.d.txt

  1  1  0.2


End File

to:
 File *.mpc.d.txt
1  1  0.2
End File

Changed lines 10-13 from:

# new linear time-invariant object

to:

## Example Model

 ! new linear time-invariant object

Changed lines 20-31 from:

# y[k] = C * x[k] + D * u[k]

to:
 ! Model information
! continuous form
! dx/dt = A * x + B * u
!     y = C * x + D * u
!
! dimensions
! (nx1) = (nxn)*(nx1) + (nxm)*(mx1)
! (px1) = (pxn)*(nx1) + (pxm)*(mx1)
!
! discrete form
! x[k+1] = A * x[k] + B * u[k]
!   y[k] = C * x[k] + D * u[k]

Changed line 39 from:

# A matrix (row, column, value)

to:
 ! A matrix (row, column, value)

Changed line 46 from:

# B matrix (row, column, value)

to:
 ! B matrix (row, column, value)

Changed line 54 from:

# C matrix (row, column, value)

to:
 ! C matrix (row, column, value)

Changed line 61 from:

# D matrix (row, column, value)

to:
 ! D matrix (row, column, value)

Changed lines 8-64 from: to: # new linear time-invariant object

Model control

  Objects
mpc = lti
End Objects


End Model

# y[k] = C * x[k] + D * u[k]

File *.mpc.txt

  sparse, continuous  ! dense/sparse, continuous/discrete
2      ! m=number of inputs
3      ! n=number of states
3      ! p=number of outputs


End File

# A matrix (row, column, value)

File *.mpc.a.txt

  1  1  0.9
2  2  0.1
3  3  0.5


End File

# B matrix (row, column, value)

File *.mpc.b.txt

  1  1  1.0
2  2  1.0
3  1  0.5
3  2  0.5


End File

# C matrix (row, column, value)

File *.mpc.c.txt

  1  1  0.5
2  2  1.0
3  3  2.0


End File

# D matrix (row, column, value)

File *.mpc.d.txt

  1  1  0.2


End File

November 04, 2008, at 07:54 PM by 158.35.225.231 -
Changed line 6 from:

These models are typically in the finite impulse response form or linear state space form. Either model form can be converted to an APMonitor for a linear MPC upgrade. Once the linear MPC model is converted, nonlinear elements can be added to avoid multiple model switching, gain scheduling, or other ad hoc measures commonly employed because of linear MPC restrictions.

to:

These models are typically in the finite impulse response form or linear state space form. Either model form can be converted to an APMonitor for a linear MPC upgrade. Once in APMonitor form, nonlinear elements can be added to avoid multiple model switching, gain scheduling, or other ad hoc measures commonly employed because of linear MPC restrictions.

November 04, 2008, at 07:54 PM by 158.35.225.231 -
Changed line 6 from:

These models are typically in the finite impulse response form or linear state space form. Either model form can be converted to an APMonitor for a linear MPC upgrade. Once the linear MPC model is converted, nonlinear elements can be added to avoid multiple model switching, gain scheduling, or other ad hoc measures commonly employed because of linear MPC shortcomings.

to:

These models are typically in the finite impulse response form or linear state space form. Either model form can be converted to an APMonitor for a linear MPC upgrade. Once the linear MPC model is converted, nonlinear elements can be added to avoid multiple model switching, gain scheduling, or other ad hoc measures commonly employed because of linear MPC restrictions.

November 04, 2008, at 07:54 PM by 158.35.225.231 -
Changed lines 4-6 from:

Linear model predictive controllers are based on models in the finite impulse response form or linear state space form. Either model form can be converted to a form that APMonitor uses for estimation and control.

to:

Model Predictive Control, or MPC, is an advanced method of process control that has been in use in the process industries such as chemical plants and oil refineries since the 1980s. Model predictive controllers rely on dynamic models of the process, most often linear empirical models obtained by system identification.

These models are typically in the finite impulse response form or linear state space form. Either model form can be converted to an APMonitor for a linear MPC upgrade. Once the linear MPC model is converted, nonlinear elements can be added to avoid multiple model switching, gain scheduling, or other ad hoc measures commonly employed because of linear MPC shortcomings.

November 04, 2008, at 07:38 PM by 158.35.225.231 -
Changed lines 1-2 from:

to:

## Linear Model Predictive Control 