# How can I apply different control approach without having a state space model? [closed]

Recently i am working on a hydraulic control system of a vehicle. But in this system I don't have any mathematical modeling of the system so i am not able to get any state space model for the given system. I have to control the length of Piston in Hydraulic Cylinder by giving input of desired piston position. Modeling of this system is established in Matlab/Simulink using physical modeling tools SimScape Toolbox and simFluids. As one approach i had already try to apply a feedback with P-control as show in the figure Matlab System and also the gain of P control is derived by trial and error.

Now if i want to apply state obeserver or optimal Control than how can i apply on this given system.

And is necessary to derive mathematical model of this system to desing controller?

Thank You.

• I am closing this question as it has been asked both at robotics and engineering. It has received better answers elsewhere. Do not crosspost --- this encourages duplication of effort and is very rude. – davidlowryduda Nov 13 '16 at 21:40

## 1 Answer

The theory of feedback control design requires mathematical models. If you don't have one, there are two main approaches:

1 - Use standard controllers, and tune them using heuristic methods. For example, tune a PID using a combination of Ziegler-Nichols rules of thumb and trial and error. Or even try a fuzzy logic controller. This all may work after a fair amount of labor, if the process is intuitive enough, and obtaining the highest performance is not really necessary.

2 - Obtain a model using experimental or simulation data. The theory of linear system identification is very well developed, and the Matlab packages often ar able to provide reasonably good models. Then apply your favorite controle design method to the model obtained from the data.

3 - There is a 3rd approach - use adaptive control. But I have to warn you that the theory is not straightforward and the methods don't furnish reliably good controllers.

• matlab packages as you mentioned in answer, is there control system or system identification toolbox is useful or not for this condition? – Krunal V Nov 7 '16 at 13:58
• They are both useful. 1st use a sys id toolbox, then use a control design toolbox on the model you obtained. – Pait Nov 7 '16 at 14:15
• Thanks for your suggestion, i will let you know as soon as i get result using this toolbox – Krunal V Nov 8 '16 at 8:42