Force Tracking Control for the Hydraulic Servosystem using a Proportional Pressure Control Valve

The fluid power system is applied to various fields of modern industries because it is able both to generate great force or torque and to control precisely the movement of hydraulic actuators. Amongst those to which the fluid power is applied, active suspension system and four wheel steering system on a passenger car have the force control hydraulic servosystem. The electro-hydraulic servo valve and the proportional pressure control valve can be used as control valve, an essential component of the force control hydraulic servosystem. The electro-hydraulic servo valve requires feedback of control output in the hydraulic servosystem. But the proportional pressure control valve does not require feedback of control output in the force control servosystem. In this paper, the linear model of the hydraulic servosystem for force tracking control which consists of a proportional pressure control valve and a double acting cylinder is derived. The performance of the hydraulic servosystem is analysed through computer simulations. And the limitations on designing the controller in feedback control system are studied. In addition, performance of position tracking control system as well as the limitations on feedback control is examined. In the force tracking hydraulic servosystem, the velocity of piston acts as feedback term from the position output of the cylinder to pressure differential across the piston. Therefore, the poles of the plant manifest themselves as the zeros of the open-loop transfer function. Moreover, these zeros can't be changed via feedback and simple algorithms are severely bandwidth limited. In the position tracking control system, by the stable pole-zero cancellation the poles of the plant do not appear as the zeros of the open-loop transfer function. The result from the study shows that a simple algorithm for force tracking purposes beyond the bandwidth limitation is not suitable and the need of more advanced algorithms are confirmed. On the other hand, It is confirmed that the position control system is properly controlled by means of simple algorithms.Abstract = 1 기호설명 = 3 제 1 장 서론 = 6 제 2 장 시스템의 구조와 이론 해석 = 8 2.1 비례 압력 제어 밸브의 구조와 동작원리 = 8 2.2 시스템의 구성 = 12 2.3 시스템의 수학적 모델 = 12 2.3.1 시스템의 수학적 모델 = 12 2.3.2 선？奐某？ 및 전달함수 = 18 제 3 장 힘 추적 제어 분석 = 23 3.1 시스템의 응답 특성 = 23 3.2 힘 추적 제어 = 28 3.3 힘 추적 피드백 제어계의 제어기 설계 = 32 제 4 장 위치 추적 제어 분석 = 41 4.1 위치 추적 제어 = 41 4.2 위치 추적 피드백 제어계의 제어기 설계 = 44 제 5 장 고찰 및 결론 = 49 참고문헌 = 51 부록 = 5

Predicting dynamic performance limits for servosystems with saturating nonlinearities

A generalized treatment for a system with a single saturating nonlinearity is presented and compared with frequency response plots obtained from an analog model of the system. Once the amplitude dynamics are predicted with the limit lines, an iterative technique is employed to determine the system phase response. The saturation limit line technique is used in conjunction with velocity and acceleration limits to predict the performance of an electro-hydraulic servosystem containing a single-stage servovalve. Good agreement was obtained between predicted performance and experimental data

Position control of electro-hydraulic actuator system using fuzzy logic controller optimized by particle swarm optimization

The position control system of an electro-hydraulic actuator system (EHAS) is investigated in this paper. The EHAS is developed by taking into consideration the nonlinearities of the system: the friction and the internal leakage. A variable load that simulates a realistic load in robotic excavator is taken as the trajectory reference. A method of control strategy that is implemented by employing a fuzzy logic controller (FLC) whose parameters are optimized using particle swarm optimization (PSO) is proposed. The scaling factors of the fuzzy inference system are tuned to obtain the optimal values which yield the best system performance. The simulation results show that the FLC is able to track the trajectory reference accurately for a range of values of orifice opening. Beyond that range, the orifice opening may introduce chattering, which the FLC alone is not sufficient to overcome. The PSO optimized FLC can reduce the chattering significantly. This result justifies the implementation of the proposed method in position control of EHAS

Full- and Reduced-order Model of Hydraulic Cylinder for Motion Control

This paper describes the full- and reduced-order models of an actuated hydraulic cylinder suitable for system dynamics analysis and motion control design. The full-order model incorporates the valve spool dynamics with combined dead-zone and saturation nonlinearities - inherent for the orifice flow. It includes the continuity equations of hydraulic circuits coupled with the dynamics of mechanical part of cylinder drive. The resulted model is the fifth-order and nonlinear in states. The reduced model neglects the fast valve spool dynamics, simplifies both the orifice and continuity equations through an aggregation, and considers the cylinder rod velocity as output of interest. The reduced model is second-order that facilitates studying the system behavior and allows for direct phase plane analysis. Dynamics properties are addressed in details, for both models, with focus on the frequency response, system damping, and state trajectories related to the load pressure and relative velocity.Comment: 6 pages, 6 figures, IEEE conferenc

Optimization of Sliding Mode Control using Particle Swarm Algorithm for an Electro-hydraulic Actuator System

The dynamic parts of electro-hydraulic actuator (EHA) system are widely applied in the industrial field for the process that exposed to the motion control. In order to achieve accurate motion produced by these dynamic parts, an appropriate controller will be needed. However, the EHA system is well known to be nonlinear in nature. A great challenge is carried out in the EHA system modelling and the controller development due to its nonlinear characteristic and system complexity. An appropriate controller with proper controller parameters will be needed in order to maintain or enhance the performance of the utilized controller. This paper presents the optimization on the variables of sliding mode control (SMC) by using Particle Swarm Optimization (PSO) algorithm. The control scheme is established from the derived dynamic equation which stability is proven through Lyapunov theorem. From the obtained simulation results, it can be clearly inferred that the SMC controller variables tuning through PSO algorithm performed better compared with the conventional proportionalintegral-derivative (PID) controller

Performance Analysis of Position Tracking Control With PID Controller Using An Improved Optimization Technique

An Electro-Hydraulic Actuator (EHA) system is usually utilized in production industry such as automotive industry which requires precision, high force and long operating hours. When dealing with the production of engineering parts that require precision, high force and long operating hours, a controller is usually required. It is observed from the literature, an appropriate tuning technique is essential in order to obtain optimal controller’s performance. Therefore, a computational tuning technique, namely Priority-based Fitness Particle Swarm Optimization (PFPSO) is proposed to obtain the parameters of the Proportional-Integral-Derivative (PID) controller in this paper. The performance of the EHA system will be evaluated and compared based on the priority characters of the PFPSO tuning technique, which included settling time and overshoot percentage that affect the output results of the EHA system. As a result, it is observed that the priority based on settling time produced a better result, which enhances the steady-state performance of the EHA system that fulfills the requirement of the precision contro

Optimization Techniques In PID Controller On A Nonlinear Electro-Hydraulic Actuator System

The controller is an important component in the nonlinear control system, especially for the system that needs accuracy in position tracking. Electro-Hydraulic Actuator (EHA) system i s a popular nonlinear system that is used by researchers. Proportional- Integral-Derivative (PID) controller is the most popular controller that is normally used in the industry. This i s mainly because of i ts simplicity in the design process. However, there are three constants that need to be assigned in the PID controller, often we called thi s as the parameters s election process or the PID tuning process. In this paper, a comparison s tudy for the selection process of the PID parameters process will be conducted among Ziegler-Nichols tuning method, conventional Particle Swarm Optimization (PSO) technique and Priority-based Fitness Particle Swarm Optimization (PFPSO) technique. PFPSO is one of the improved versions of the conventional PSO technique. The s imulation study wi ll be conducted on a nonlinear Electro-Hydraulic Actuator (EHA) system. A simple robustness test on the PID controller will be evaluated in terms of actuator internal leakage. Results showed that the PID performed better whe n its controller's parameters are selected using PFPSO technique rather than the Ziegler-Nichols method and conventional PSO technique