Rozaimi Ghazali

System identification of electro-hydraulic actuator servo system

This paper presents the system identification process done on an industrial Electro-Hydraulic Actuator (EHA) system. The model obtained through system identification by aid of System Identification Toolbox of MATLAB and System Identification Toolkit of LabVIEW. Attraction of system identification is ability to obtain systems model with sets of input and output data; without need of prior knowledge on system. The model is later validated with the actual performance of real EHA system.

Modeling and controller design of an industrial hydraulic actuator system in the presence of friction and internal leakage

This paper presents a robust controller scheme and its capabilities to control the position tracking performance of an electro-hydraulic actuator system. Sliding mode control with fixed and varying boundary layer is proposed in the scheme. It is aimed to compensate nonlinearities and uncertainties caused by the presence of friction and internal leakage. Its capabilities are verified through simulations in Matlab Simulink environment. The friction was represented by the LuGre model and the internal leakage was assumed to change. The results indicate that the scheme successfully improves the robustness and the tracking accuracy of the system. This improvement offers a significant contribution in the control of modern equipment positioning applications.

On-line identification of an electro-hydraulic system using recursive least square

This paper presents experimental on-line identification of an electro-hydraulic system represented by a discrete time model. A recursive least square (RLS) method is used to estimate the unknown parameters of the system based on auto regression with exogenous input (ARX) model. Residual analysis is used for model validation. Results are presented which show variations in parameters of the electro-hydraulic system.

PID controller design for an industrial hydraulic actuator with servo system

Electro-hydraulic system (EHS) consists of several dynamic parts which are widely used in motion control application. These dynamic parts need to be controlled to determine direction of the motion. Mathematical model of EHS is required in order to design a controller for the system. In this paper, system identification technique is used for system modeling. Model of the system is estimated by using System Identification Toolbox in Matlab. This process began with collection of input and output data from experimental works. The data collected is used for model estimation. Auto Regressive with eXogeneous input (ARX) model is chosen as model structure of the system. Based on the input and output data of the system, best fit criterion and correlation analysis of the residual is analyze to determine the adequate model for representing the EHS system. By using Ziegler-Nichols tuning method, PID controller is designed for the model chosen through simulation in Simulink. In order to verify this controller, it is applied to the real time system and the performance of the system is monitored. The result obtained shows that the output of the system with controller in simulation mode and experimental works is almost similar. The output of the system also tracked the input given successfully.

Open-loop and closed-loop recursive identification of an electro-hydraulic actuator system

This paper presents experimental work on recursive identification of an electro-hydraulic system that represented by a discrete-time model in open-loop and closed-loop configurations. A recursive least square (RLS) method is used to estimate the unknown parameters of the system based on auto regression with exogenous input (ARX) model. Residual analysis is utilized for a model validation. Results are presented which show variations in parameters of the electro-hydraulic system. From the results obtained, position tracking for electro-hydraulic system can be implemented by using conventional proportional-integral-derivative (PID) controller with the aim of the modeling validation.

Position tracking control of an electro-hydraulic servo system using sliding mode control

This paper evaluates the position tracking performance of an electro-hydraulic hydraulic servo (EHS) system using sliding mode control (SMC). The EHS system is established in modelling process by consider its nonlinearities with a friction model. The control strategy is derived from developed dynamics equation and stability of the control system is theoretically proven by Lyapunov theorem. Simulation results demonstrate the proposed controller is highly robust and capable to cope with the uncertainties and disturbances occur during the position tracking control. It is also shows that the proposed controller can achieve better tracking performance compared with conventional PID controller.

Simulation and experimental studies on perfect tracking optimal control of an electrohydraulic actuator system

This paper presents a perfect tracking optimal control for discrete-time nonminimum phase of electrohydraulic actuator (EHA) system by adopting a combination of feedback and feedforward controller. A linear-quadratic regulator (LQR) is firstly designed as a feedback controller, and a feedforward controller is then proposed to eliminate the phase error emerged by the LQR controller during the tracking control. The feedforward controller is developed by implementing the zero phase error tracking control (ZPETC) technique in which the main difficulty arises from the nonminimum phase system with no stable inverse. Subsequently, the proposed controller is performed in simulation and experimental studies where the EHA system is represented in discrete-time model that has been obtained using system identification technique. It also shows that the controller offers better performance as compared to conventional PID controller in reducing phase and gain error that typically occurred in positioning or tracking systems.

Optimal tuning of PID+PD controller by PFS for Gantry Crane System

This paper presents a combination of the Priority Fitness Scheme (PFS) and optimization techniques to find the optimal performances of the Gantry Crane System. Control algorithm that based on the PFS will be designed and used as fitness function in PSO and BPSO. PFS are prioritized based on Steady State Error (SSE), Overshoot (OS) and Settling Time (Ts) according to the requirements. The system model is derived using the Lagrange equation and PID+PD controller is developed for positioning and oscillation control. System responses, including trolley displacement and payload oscillation are observed and analyzed. It is expected the optimal load transfers offer significant time saving with limited swing and smooth motions via PFPSO and PFBPSO.

System identification of electro-hydraulic actuator system with pressure and load effects

Electro-hydraulic actuator (EHA) system has become one of the most prominent actuator in the past decades. Therefore, it is crucial to attain structural insight into the characteristics of the particular system. This paper presents system identification of EHA system using non-recursive or offline technique where the mathematical model is determined first by considering fixed supply pressure and load. Then, load variation is demonstrated to evaluate the parameter changes. Lastly, supply pressure is changed in order to show the significant effect in the model parameters. The finding shows that the load variation produces insignificant effect in the model parameters due to the limitations of the developed EHA system workbench. However, the supply pressure shows significant effect in the plant model parameters. As conclusion, the robustness and adaptability assessment in the controller design might be appropriately observed in future research works by using the supply variation for the existing EHA system workbench.

Sliding mode control with switching-gain adaptation based-disturbance observer applied to an electro-hydraulic actuator system

This paper presents a new robust control scheme using sliding mode control associated with disturbance observer enhanced by varying boundary layers technique. Switching-gain of the sliding mode is adaptable on the estimated disturbance. The scheme is developed to guarantee tracking accuracy of an electro-hydraulic actuator system with robust and smooth control actions in the existence of uncertainties and the changes of external load disturbance. Robustness and smoothness of the control actions is assured if the switching gain of the control law is greater and adaptable on the bounds of the uncertainties and the disturbance. Moreover, the smoothness of the control input is enhanced by varying boundary layers technique based on the estimated disturbance. The capability of the proposed controller is validated through simulation. The simulation results indicate that the proposed scheme ensures the tracking performance with smooth control actions in different levels of the external load disturbance. This scheme offers a significant efficiency of energy in the control of EIlA systems.