K P, K I, and K D, are usually fixed during operation. Traditionally, the parameters of a classical PID controller, i.e. Moreover, it has simple architecture and conceivable physical intuition of its parameter. Therefore, it seems to be quite difficult to perform a high precision servo control by using linear control method Rong-Fong Fung et al, 1997 Aliyari et al, 2007 Pratumsuwan et al, 2010).Ĭlassical PID controller is the most popular control tool in many industrial applications because they can improve both the transient response and steady state error of the system at the same time. For example, they are the highly nonlinear phenomena such as fluid compressibility, the flow/pressure relationship and dead-band due to the internal leakage and hysteresis, and the many uncertainties of hydraulic systems due to linearization. However, there are also many challenges in the design of SEHS. The Servo Electro-hydraulic System (SEHS), among others, is perhaps the most important system because it takes the advantages of both the large output power of traditional hydraulic systems and the rapid response of electric systems.

Although the high cost of hydraulic components and power unit, loss of power due to leakage, inflexibility, nonlinear response, and error-prone low power operation tends to limit the use of hydraulic drives, they nevertheless constitute a large subset of all industrial drives and are extensively used in the transportation and manufacturing industries ( Merrit, 1976 Rong-Fong Fung et al, 1997 Aliyari et al, 2007). It has many distinct advantages such as the response accuracy, self-lubricating and heat transfer properties of the fluid, relative large torques, large torque-to-inertia ratios, high loop gains, relatively high stiffness and small position error. The application of hydraulic actuation to heavy duty equipment reflects the ability of the hydraulic circuit to transmit larger forces and to be easily controlled.

Labview pid control valve