MATLAB: Neural network poor performance

neural network toolboxperformance

Hello this is the first time I work with the neural network toolbox, I designed a network using newff, the goal is to approximate the input vector wich is a 4×600 matrix of MAV's taken from 4 muscles, to an output an expected angle.
I followed the instructions given at: http://www.mathworks.com/matlabcentral/answers/137-how-do-i-improve-my-neural-network-performance
however when I look at the regression plot, I'm getting a very low regression index, R=0.16882, the fit line it's almost horizontal and there is a lot of dispersion.
If someone could point me out in the right direction, I'd be gratefull.
Here is my code:
net = newff(Input,Target,20);
net.trainParam.goal=1e-6;
net.trainParam.max_fail=6;
net.performFcn='msereg';
net.performParam.ratio=0.5; 
net,tr] = train(net,Input,Target);
yTargets = sim(net,Input);
plotregression(Target,yTargets);

Best Answer

Find, H, the smallest number of hidden nodes that will yield a satifactory design by looping over nH candidate values and trying Ntrials different designs for each value of H. Then choose the best of the nH*Ntrials designs.
I typically look at nH = 10, Ntrials = 10 first. Then accept or modify depending on the result.
Hope this helps.
Greg
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