It seems that I still need more help on this....
Hello guys,
Some time ago I asked question about feedforward algorithm. Peter explained and attached the file to help me understand. After first reading I thought, "that's it, it is so simple". Now I need to deeply learn feedforward i.e I need to implement it. Peter was very kind and attached the file. In the first part, there is a small example of servo system. If I understood this correctly, the whole goal is to make Gc transfer function so that represents 1/Ga, where Ga is transfer function of plant. In such case there are no need for closed loop. I extended this example.
Ga = Ka/(s+a). Now we have: Gc =1/Ga=(s+a)/Ka = s/Ka+1/K. Now, in the structure I see that closed loop is still used, and these gains are applied in parallel with clasiccal PID. So I can conclude that this makes whole control loop more robust. Now, one can come to that structure.
If I understood good, first one needs to imagine that no closed loop is used which means that input to the controller is desired response (target generator). In that case Gc = CO/target =>
s*Target/Ka+Target/K = CO.
Now we returned to closed loop control and apply that gains in parallel no matter we assumed control loop will not be used in the first place.
Let's put some real values of parameters:
Transfer function of the plant is G=10/(s+2), so feedforward controller is:Target*s/10+Target/5 = CO????
I don't actaully see how this can work, I mean since we already have PID, will these controller fight each other?
I understand idea behind feedforward, I just don't understand why we assume one structure, calculate gains, then apply that gins on a different structure?
Hello guys,
Some time ago I asked question about feedforward algorithm. Peter explained and attached the file to help me understand. After first reading I thought, "that's it, it is so simple". Now I need to deeply learn feedforward i.e I need to implement it. Peter was very kind and attached the file. In the first part, there is a small example of servo system. If I understood this correctly, the whole goal is to make Gc transfer function so that represents 1/Ga, where Ga is transfer function of plant. In such case there are no need for closed loop. I extended this example.
Ga = Ka/(s+a). Now we have: Gc =1/Ga=(s+a)/Ka = s/Ka+1/K. Now, in the structure I see that closed loop is still used, and these gains are applied in parallel with clasiccal PID. So I can conclude that this makes whole control loop more robust. Now, one can come to that structure.
If I understood good, first one needs to imagine that no closed loop is used which means that input to the controller is desired response (target generator). In that case Gc = CO/target =>
s*Target/Ka+Target/K = CO.
Now we returned to closed loop control and apply that gains in parallel no matter we assumed control loop will not be used in the first place.
Let's put some real values of parameters:
Transfer function of the plant is G=10/(s+2), so feedforward controller is:Target*s/10+Target/5 = CO????
I don't actaully see how this can work, I mean since we already have PID, will these controller fight each other?
I understand idea behind feedforward, I just don't understand why we assume one structure, calculate gains, then apply that gins on a different structure?