optimization problem programming

Hello every one

I have designed a program of one controller for using in plc by scl language. but i found that my program need constraint and for imposing constraint into control program need optimization problem be solved. how can i define this constraints for my input?

Thanks alot

sajjad

Hello sajjad;

Could you clarify your request? We would like to help you but your explanation is much too vague.

We need to see some of your code,  with information on  the CPU and programming software you are using, along with a description of what you need from us.

Hope thos helps,

Daniel chartier

dchartier

Hello sajjad;

Could you clarify your request? We would like to help you but your explanation is much too vague.

We need to see some of your code,  with information on  the CPU and programming software you are using, along with a description of what you need from us.

Hope thos helps,

Daniel chartier

 first thank you for answar my question. i want to generate scl codes of matlab code. i wrote a function in matlab  related to model predictive control and then generate plc code of it but  plc coder dont support optimization problem and i want to know is there another way to impose constraint or not. i want to generate this below matlab codes to plc codes but in optimization section i face with problem

t0=0;
tf=1000;
ts=1;
t=t0:ts:tf;
Nt=numel(t);
Am=[.9996 .0383 .0131 -0.322;-.0056 .9647 .7446 .0001;.0020 -.0097 .9543 0;.0001 -.0005 .0978 1];
Bm=[.0001 .1002;-.0615 .0183;-.1133 .0586;-.0057 .0029];
Cm=[1 0 0 0;0 -1 0 7.74];
q=size(Cm,1);
n=size(Am,1);
m=size(Bm,2);
Om=zeros(q,n);
Np=30;
Nc=20;
I=eye(q);
A=[Am Om';Cm*Am I];
B=[Bm;Cm*Bm];
C=[Om I];
F=zeros(q*Np,n+q);
for i=1:Np
F(q*i-q+1:q*i,:)=C*A^i;
end
PHI=zeros(q*Np,Nc*m);
PHI1=zeros(q*Np,m*Nc);
for i=1:Np
for j=1:i
PHI(q*i-q+1:q*i,m*j-m+1:m*j)=C*A^(i-j)*B;
end
end
for i=1:2*Nc
PHI1(:,i)=PHI(:,i);
end
%% main loop
Rs(1 , :) = [ones(floor(Nt/4) , 1)' , 2*ones(floor(Nt/4) , 1)' , -ones(floor(Nt/4) , 1)' , zeros(floor(Nt/4+1) , 1)'] ;
Rs(2 , :) = [ones(floor(Nt/4) , 1)' ,-2*ones(floor(Nt/4) , 1)' , ones(floor(Nt/4) , 1)' , zeros(floor(Nt/4+1) , 1)'] ;
y=zeros(q,Nt);
du=zeros(m,Nt);
x=zeros(size(A,1),Nt);
R=1;
y1=zeros(1,Nt);
y2=zeros(1,Nt);
R1=zeros(2*Np,Nt);

for i=1:Nt
for j=1:Np
R1(2*j-1:2*j,i)=Rs(:,i);
end
end
for i=1:Nt-1
Freeresponse=F*x(:,i);
dU = (PHI1'*PHI1 + R )\(PHI1' * (R1(:,i) - Freeresponse)) ;
du1(i) = dU(1) ;
du2(i) = dU(2) ;
x(: , i+1) = A*x(:, i)+ B*[du1(i);du2(i)] ;
y(: , i+1) = C*x(: , i+1) ;
end
y1=y(1,1:Nt);
y2=y(2,1:Nt);

Hello,

tell us location of your expected optimization areas and how you come to idea that PLC doesn't support optimization.

Hello sajjad;

Here are some documents found on the web that could probably give you some hints for your project. Having never done a conversion from Matlab to s7-SCL myself, I can only point to work done by others:

• Model Predictive Control in the Chemical Process Industry hosted by Industrial Controllers

ftp://ftp.esat.kuleuven.be/pub/stadius/ida/reports/13-161.pdf

The implementation on the PAC is straightforward. An existing C implementation of qpOASES and C code generated by the CVXGEN web tool has been used to implement the QP solvers. The C-code for the Hildreth solver is translated from an existing Matlab implementation based on work by [87]. The qpOASES and Hildreth implementation on the PLC are written from scratch in S7-SCL, based on the Matlab implementation

• Towards Online Model Predictive Control on a Programmable Logic Controller

https://www.hindawi.com/journals/mpe/2012/912603/

There exists no compiler to transform the C/C++ source code to a running binary on a Siemens PLC. Therefore, the C/C++ code has to be translated into S7-SCL (STL). Although possible, this is a time consuming step. In this project, the qpOASES and hildreth solvers are translated to S7-SCL. The qpOASES solver is translated without the hotstarting possibilities and the general constraint handling code. Instead, only the part that handles bounds is translated. CVXGEN cannot generate STL code, and a manual translation of the generated code is impossible, hence; it is not used.

To calculate the appropriate inputs of the system and solve the QP, following built-in function blocks (FBs) and organization blocks (OBs) are programmed..

• -Simulink PLC Coder:

http://files.matlabsite.com/docs/books/matlab-docs/simulink_plc_coder_plc_st_r2015a.pdf

Simulink® PLC Coder™ generates hardware-independent IEC 61131-3 Structured Text from Simulink models, Stateflow® charts, and Embedded MATLAB® functions. The Structured Text is generated in PLCopen and other file formats supported by widely used integrated development environments (IDEs). As a result, you can compile and deploy your application to numerous programmable logic controller (PLC) and programmable automation controller (PAC) devices.

Supported IDE Platforms :…

• Siemens SIMATIC STEP 7 Version 5.4 or 5.5 The Simulink PLC Coder software assumes that English systems use English S7.It assumes that German systems use German S7...

Hope this helps,

Daniel Chartier

Duris_I

Hello,

tell us location of your expected optimization areas and how you come to idea that PLC doesn't support optimization.

Hi.

This "optimization problem"has nothing to do with the optimization of processing code as one might expect. As machine designers that is what we would have expected.

The "optimization problem" that is being spoken of is in terms of process control. The process control is made better by some algorithm or method. The topic stater was hoping that these facilities are already built into the command set instructions that the PLC has.

"Predictive control" algorithm or self auto tuning (PID) is some of the methods that could be used.

I hope this puts some perspective on this topic.
Sorry - I will not be able to be helpful to the topic.

Regards.

<off topic lecture completed>

Hello #dP,

thnx for info, after also Daniel's info I understand that. I must say, never heard about this kind of optimization as is exactly from that name.

dchartier

Hello sajjad;

Here are some documents found on the web that could probably give you some hints for your project. Having never done a conversion from Matlab to s7-SCL myself, I can only point to work done by others:

• Model Predictive Control in the Chemical Process Industry hosted by Industrial Controllers

ftp://ftp.esat.kuleuven.be/pub/stadius/ida/reports/13-161.pdf

The implementation on the PAC is straightforward. An existing C implementation of qpOASES and C code generated by the CVXGEN web tool has been used to implement the QP solvers. The C-code for the Hildreth solver is translated from an existing Matlab implementation based on work by [87]. The qpOASES and Hildreth implementation on the PLC are written from scratch in S7-SCL, based on the Matlab implementation

• Towards Online Model Predictive Control on a Programmable Logic Controller

https://www.hindawi.com/journals/mpe/2012/912603/

There exists no compiler to transform the C/C++ source code to a running binary on a Siemens PLC. Therefore, the C/C++ code has to be translated into S7-SCL (STL). Although possible, this is a time consuming step. In this project, the qpOASES and hildreth solvers are translated to S7-SCL. The qpOASES solver is translated without the hotstarting possibilities and the general constraint handling code. Instead, only the part that handles bounds is translated. CVXGEN cannot generate STL code, and a manual translation of the generated code is impossible, hence; it is not used.

To calculate the appropriate inputs of the system and solve the QP, following built-in function blocks (FBs) and organization blocks (OBs) are programmed..

• -Simulink PLC Coder:

http://files.matlabsite.com/docs/books/matlab-docs/simulink_plc_coder_plc_st_r2015a.pdf

Simulink® PLC Coder™ generates hardware-independent IEC 61131-3 Structured Text from Simulink models, Stateflow® charts, and Embedded MATLAB® functions. The Structured Text is generated in PLCopen and other file formats supported by widely used integrated development environments (IDEs). As a result, you can compile and deploy your application to numerous programmable logic controller (PLC) and programmable automation controller (PAC) devices.

Supported IDE Platforms :…

• Siemens SIMATIC STEP 7 Version 5.4 or 5.5 The Simulink PLC Coder software assumes that English systems use English S7.It assumes that German systems use German S7...

Hope this helps,

Daniel Chartier

  Hello Daniel.

Thank you for your  help and guidance.Is possible to have your email?