# NARX for Multi Input Multi Output system Identification

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Karima on 10 Mar 2013
Hello, Can anyone please help how to use NARX method from the Neural Networks Tool box to perform system identification for a system that has Multi inputs Multi Outputs.Thanks.

Greg Heath on 10 Mar 2013
1. Write and test your code assuming SISO
2. Convert to MIMO and test
3. If you have problems or questions, post relevant code and error messsages
Hope this helps.
Thank you for formally accepting my answer
Greg
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Greg Heath on 10 Mar 2013
The sizes of the input and target matrices are
[ I N ] = size(x) % [ 3 N ]
[ O N ] = size(t) % [ 2 N ]

### More Answers (2)

Ahmed Hakim on 1 Apr 2013
Hello GUYS
I have the same problem
I have a model of DC motor which has two inputs (the Voltage and the Load torque) and output DC motor speed
Now I would like to identify this DC motor model with its two inputs using neural network to mimic this Motor Model
The idea is that when I change in the load torque as a disturbance the whole output of the DCM being controlled by PID is changed
So I suggested to make online identification for the DC Motor, so that when there is a disturbance change, the Neural network will identify the new MODEL and then a new design for PID will be according to this new model by Neural network
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Ahmed Hakim on 1 Apr 2013
How can I make a system identification using Neural Network for a system with Two Inputs and One output

fabian on 24 Jun 2013
I need to make the identification of a MISO system with NARX neural network. I have the following code someone can collaborate. thanks
datoshistoricos;
u=datoshistoricos(:,1:2:3:4)';
y=datoshistoricos(:,5)';
[u,us] = mapminmax(u);
[y,ys] = mapminmax(y);
y = con2seq(y);
u = con2seq(u,587);
d1 = [1:2];
d2 = [1:2];
S1 = 20;
narx_net = narxnet(d1,d2,S1);
narx_net.divideFcn = '';
narx_net.inputs{1}.processFcns = {};
narx_net.inputs{2}.processFcns = {};
narx_net.outputs{2}.processFcns = {};
[p,Pi,Ai,t] = preparets(narx_net,u,{},y);
narx_net = train(narx_net,p,t,Pi);
narx_net_closed = closeloop(narx_net);
view(narx_net_closed)
mrac_net = feedforwardnet([S1 1 S1]);
mrac_net.layerConnect = [0 1 0 1;1 0 0 0;0 1 0 1;0 0 1 0];
mrac_net.outputs{4}.feedbackMode = 'closed';
mrac_net.layers{2}.transferFcn = 'purelin';
mrac_net.layerWeights{3,4}.delays = 1:2;
mrac_net.layerWeights{3,2}.delays = 1:2;
mrac_net.layerWeights{3,2}.learn = 0;
mrac_net.layerWeights{3,4}.learn = 0;
mrac_net.layerWeights{4,3}.learn = 0;
mrac_net.biases{3}.learn = 0;
mrac_net.biases{4}.learn = 0;
mrac_net.divideFcn = '';
mrac_net.inputs{1}.processFcns = {};
mrac_net.outputs{4}.processFcns = {};
mrac_net.name = 'Model Reference Adaptive Control Network';
mrac_net.layerWeights{1,2}.delays = 1:2;
mrac_net.layerWeights{1,4}.delays = 1:2;
mrac_net.inputWeights{1}.delays = 1:2;