This paper presents Particle Swarm Optimization (PSO) algorithm, Adaptive Weighted PSO (AWPSO) algorithm and Genetic Algorithm (GA) for determining the optimal Proportional-Integral-Derivative (PID) controller’s parameters of a position control for a typical Hydraulic Servo System (HSS). The performance indices, which have been used in the optimization, are Integral Absolute Error (IAE), Integral Square Error (ISE) and Integral Time Absolute Error (ITAE). The proposed controller is implemented on a simulation model of a real time hydraulic system to know the best method for tuning the controller. The PSO method yields better tuning in terms of settling time, maximum overshoot and undershoot. Compared to GA and AWPSO results, the PSO method has been noticed to be more efficient and robust in improving the step response of a position control for hydraulic systems. A mathematical model of a hydraulic servo-system is presented. This model includes the most relevant dynamic and non-linear effects. The model describes the behavior of a REXROTH servo valve and includes the nonlinearities of friction forces, valve dynamics, oil compressibility and load influence.
Hydraulic Servo Systems (HSS) play an important role in industrial field because they can produce high torque and large forces with high speeds. The hydraulic servo system applications include, manipulators, material test machines, fatigue testing, paper machines, ships, injection molding machines, robotics, and aircraft field. The dynamics of hydraulic systems are highly nonlinear due to directional change of valve opening, friction, etc. (Sohl and Bobrow, 1999). In hydraulic control systems, one of the main purposes of control is to achieve a desired and satisfactory response from the system. A hydraulic servo system is a system consisting of motor, servo, controller, actuating cylinders, and measurement devices. Electro-hydraulic control problems are classified into position control, velocity control and force control problems.
One approach for force control of hydraulic servo system is to implement a fuzzy controller to minimize the force overshoot and maintain the load from failure (Chen et al., 2013). The acceleration feedback control using the variable structure controller in the presence of important friction nonlinearities is introduced and described in Bonchis et al. (2001). A nonlinear controller based on Lyapunov stability theories that considers the valve’s dynamics is used for position control of hydraulic servo system as mentioned in Sirouspour and Salcudean (2000).
The Proportional-Integral-Derivative (PID) controller, which represents the most common controller form of feedback systems, is widely used in industrial control systems as stated by Pedret et al. (2002) and Chang et al. (2003). It has been used to minimize the difference between a measured process output feedback and a desired set point by adjusting the process control parameters (Araki, 2002).
The main objective of...