Hydraulic Position Control System Research Articles

Anti-disturbance proportional integral attitude control and stabilization of rolling hydraulic position system

Disturbance rejection performance for rolling hydraulic position control system has always been a knotty issue. To guarantee the transient performance and improve disturbance rejection performance of the rolling hydraulic position control system, a compound controller, composed of a feedforward controller part based on proportional integral laws and a compensation part based on disturbance observer, is designed and investigated. In this article, a detailed analysis and design principles of the composite controller are provided. Additionally, stability analysis of the controller is proved using Lyapunov function adapted to the system. Finally, a rigorous analysis of the disturbance rejection performance is given with consideration of both instantaneous disturbances and low-frequency disturbances. For single pulse disturbance, the maximum error is reduced from 3.5% to 0.6%. Furthermore, for more complicated disturbance, sinusoidal disturbance is lower than 50 Hz, disturbance rejection performance decreases with increasing frequency and maximum error is reduced from 5.4% to 1.6%. The test results demonstrate that for single pulse disturbance, the maximum error is reduced from 4.12% to 0.64%. Furthermore, for more complicated disturbance, sinusoidal disturbance is lower than 50 Hz, disturbance rejection performance decreases with increasing frequency and maximum error is reduced from 2.71% to 0.70%. Both simulation and experiment results demonstrate that the proposed method possesses a better disturbance rejection performance than the proportional integral method.

Position control of hydraulic servo system using proportional-integral-derivative controller tuned by some evolutionary techniques

This paper uses a particle swarm optimization (PSO) algorithm, an adaptive weighted PSO (AWPSO) algorithm, and a genetic algorithm (GA) to determine the optimal proportional-integral-derivative controller’s parameters of a hydraulic position control system. A typical hydraulic servo system has been selected as an application. The mathematical model of this hydraulic servo system which comprises the most relevant dynamics and nonlinear effects is considered. The model simulates the behavior of a REXROTH servo valve and includes the nonlinearities of friction forces, valve dynamics, oil compressibility, and load influence. The performance indices, which have been used in the optimization process, are integral absolute error, integral square error and integral time absolute error. The proposed controller is implemented on the simulation model to identify the best method for tuning the controller. Compared with GA and AWPSO results, the PSO method has been found to be more efficient and robust in improving the step response of a position control for hydraulic systems in terms of settling time, maximum overshoot and undershoot.

Nonlinear Position Control of Digital Hydraulic Cylinder Despite Disturbance

A nonlinear controller is presented for a digital hydraulic cylinder against disturbance. We first establish the nonlinear model of digital hydraulic cylinder position control system. Then a Lyapunov function and a nonlinear controller are presented. The controller designing problem is translated into the problem of solving a linear matrix inequality. The experiment results show that the controller proposed by this paper has much better performance than traditional one.

Design of the Hydraulic System of Lead Plate Coiling Machine

This paper mainly introduces the process of lead electrolysis, the structure and working principle of lead plate coiling machine and Its’ parts, coiling machine components. First of all, rewind section hydraulic system adopts a return to the oil throttle speed control, it is stable and can bear a certain change load, can overcome the stage before the tension fluctuation of the impaction to the rotation speed of hydraulic motor. Secondly, speed and tension control system adopt electro-hydraulic servo valve and proportional relief valve are respectively to the drum speed and output torque control,it has high precision and accurate in speed and tension control. contact coiling section use electro hydraulic servo position control system with close loop control to improve the accuracy of position control. Finally, calculate parameters of each working section of hydraulic control system , verify the hydraulic component model and the rationality of the hydraulic circuit.

Modeling and Its Error Analysis for Load-Sensing Steering System

Load-sensing hydraulic steering system is universally used in wheeled machinery for good steering regulation performance and obviously saving energy effect. The load-sensing hydraulic steering system is present, and it is considered to be a mechanical and hydraulic position control system. The flow continuity equation and force balance equation of steering system is established, the transfer function of load-sensing hydraulic steering system is obtained, the system steady-state error caused by the typical input signal and load input signal on the basis of transfer function. The main parameters affecting the steady-state error are got, and it provides theoretical support for designing and improvement of load-sensing hydraulic steering system.

Mobile Robot Hydraulic Drive Energy-Saving Circuit Simulation Based on the High-Frequency Switching Valve

Due to the constraints from weight, volume and other various factors, mobile robot hydraulic drive system uses single pump and multi-actuator hydraulic drive structure. The high efficiency of the structure is the key to the successful application in hydraulic robot. The traditional servo valve control system possesses good position control ability, but it has the problem of bilateral throttling loss and great valve port pressure decrease. This paper proposes a hydraulic position control system based on high-frequency switching valve, which controls valve port opening and closing, through the PWM signals, so as to control flows, guarantee the position control precision as well as reduce the required system pressure, thereby achieving the effect of energy conservation. By using AMESim and Adams co-simulation and simulating the real stress environment, the feasibility of energy-saving in high frequency switching valve circuit has been verified.

Active Disturbance Rejection Control for Hydraulic Position Control System of High-Quality Cold Rolling Mill

Active disturbance rejection controller (ADRC) instead of the conventional PID controller in the hydraulic position control system is proposed to satisfy high accuracy and speed requirements in cold rolling mill. Based on the simplified model, frequency-domain analysis of the two kinds of controllers is performed. The results show that ADRC produces better performances, such as bandwidth, stability margins. Because of the extended state observer (ESO) that can estimate and compensate the tracking system in real time, ADRC reduces the dependence on accurate mathematical model, improves anti-disturbance capability of the system, and maintains good dynamic characteristics. The simulation results verified the effect of the conclusion.

Modified Generalized Predictive Control of Networked Systems With Application to a Hydraulic Position Control System

This paper is concerned with the design of networked control systems using the modified generalized predictive control (M-GPC) method. Both sensor-to-controller (S-C) and controller-to-actuator (C-A) network-induced delays are modeled by two Markov chains. M-GPC uses the available output and prediction control information at the controller node to obtain the future control sequences. Different from the conventional generalized predictive control in which only the first element in control sequences is used, M-GPC employs the whole control sequences to compensate for the time delays in S-C and C-A links. The closed-loop system is further formulated as a special jump linear system. The sufficient and necessary condition to guarantee the stochastic stability is derived. Simulation studies and experimental tests for an experimental hydraulic position control system are presented to verify the effectiveness of the proposed method.

A Study on the Effects of Servovalve Lap on the Performance of a Closed - Loop Electrohydraulic Position Control System

This paper deals with a closed–loop position control of a double acting and double–rod actuator using an electrohydraulic servovalve (EHSV). This system is studied by using symmetric critical center spool valve (zerolapped) and open center spool valve (underlapped). The nonlinear dynamic behavior of each case is undertaken and simulated. The system is modeled by using five state variables (piston position, piston velocity, actuator pressures, and servovalve spool displacement) and is tested under different step inputs. The EHSV is modeled with a first order differential equation. The closed-loop system stability is investigated by introducing equilibrium state into Jacobian matrix and determining the eignvalues. Viscous friction and compressibility of oil are included in the modeling of the system. Because the electrohydraulic position servo system is not very sensitive to coulomb friction and piston leakage they are neglected. The work showed that when the underlapped servovalve operates in the underlap region, the hydraulic position control system has more stable operation and better transient responses. Keywords: Zerolap, Underlap, EHSV, Steady-State Characteristics, Dynamic Response, Position Control, Modeling, Simulation.

Energy-regulation based variable speed hydraulic cylinder position control system

Variable speed hydraulic control systems were widely used because of the good characteristic of power adaptive and energy-saving. But the dynamic characteristic of variable speed hydraulic control systems is slow, such systems are only suitable for the applications which don’t require fast dynamic response. To improve the dynamic characteristics of the variable speed hydraulic control systems, an energy regulation device was schemed out to be added on the systems, this will form a new type of hydraulic control system(energy-regulation variable speed hydraulic control system). The energy regulation device can absorb redundant oil fluid during system deceleration period, as well as release oil flow during system acceleration period. The composition of the energy regulation device and the energy-regulation variable speed hydraulic control was introduced, and the nonlinear math model of the whole system was derived. Digital simulation of the system was carried out and the simulation results shows that this type of system can improve the dynamic greatly while the energy cost is very little.

CPLD based DIVSC of hydraulic position control systems

The hydraulic systems own the large torque to volume ratio. Therefore, they are widely used in steel manufactory. The analog Integral variable structure control has been successfully simulated on the electrohydraulic servo control. Due to the wide application of hydraulic components in industry needing higher torque, this paper extends the research to the digital implementation. For the digital implementation, the discrete existence conditions of sliding mode are introduced to adapt the IVSC to the discrete systems. The system equations are also extended to more general forms. Due to the great development in ASIC, the proposed control rule is implemented by the CPLD chips. Experimental results will show the discrete integral variable structure control has the robustness to against the parameter derivations and disturbances. The prototype board also shows the practical capability of the proposed method.

Theoretical and experimental investigation of a pulse-width modulated digital hydraulic position control system

In this study, the open loop and closed loop behaviours of a pulse-width modulated hydraulic system are investigated both theoretically and experimentally. First a mathematical model is formulated for the system and methods for obtaining system responses to pulse-width modulated inputs are developed. Using these methods, the responses of the servo valve, the open loop as well as closed loop hydraulic systems are calculated for pulse-width modulated step and sinusoidal inputs. Effect of pulse frequency on the sinusoidal response is investigated. An experimental set-up, which consists of a PC as the controller, a pulse-width modulator, a servo valve driven hydraulic system and feedback elements, was constructed. Experiments show that precise position control can be achieved by using pulse-width modulated inputs in electro-hydraulic control systems. The results obtained for sinusoidal reference inputs show that the pulse frequency should be more than 50 times the reference input frequency for a satisfactory performance of the tested system, if the reference frequency is less than 10 Hz.

APPLICATION OF OPTIMAL-TUNING PID CONTROL TO INDUSTRIAL HYDRAULIC SYSTEMS

This paper is concerned with real-time optimal-tuning PID control design for industrial hydraulic systems. Several optimal-tuning controller design techniques are used for a hydraulic position control system. After analysis on the system, a nonlinear dynamical model is derived. A nonlinear PID control scheme with inverse of dead zone is introduced to overcome the dead zone in this hydraulic system. An optimal PID controller is designed to satisfy desired time-domain performance requirements. Using the adaptive model, an optimal-tuning PID control scheme is proposed to provide optimal PID parameters even in the case where the system dynamics are time variant. To implement the optimal-tuning control in practice safely, a control performance prediction strategy is integrated. These control techniques are implemented on dSPACE and are also demonstrated by a number of experiments on a hydraulic position control test rig.

Optimal-tuning PID control for industrial systems

Abstract Three optimal-tuning PID controller design schemes are presented for industrial control systems in this paper. They are time-domain optimal-tuning PID control, frequency-domain optimal-tuning PID control and multiobjective optimal-tuning PID control. These schemes can provide optimal PID parameters so that the desired system specifications are satisfied even in case where the system dynamics are time variant or the system operating points change. They are applied to three industrial systems, a hydraulic position control system, a rotary hydraulic speed control system and a gasifier, respectively.

Research on stability and minimum orifice area of hydraulic servo position control system

This paper reports results of research on the stability of a hydraulic servo position system using generalization pulse code modulation (GPCM) and common on/off valves for hydraulic servo control. The describing function was first used to analyze the system's stability, and based on the nonlinear theory, an equation calculating the minimum orifice area of GPCM valves was derived by applying results of analysis on the stability of the GPCM control system. In the end, aimed at developing a hydraulic servo position system to be used in a paint robot, simulation and experiment were carried out. The results show that the theoretical conclusions accorded with practical results.

Optimal-Tuning PID Control for Industrial Systems

Three optimal-tuning PID controller design schemes are considered for industrial process control in this paper, which are time-domain optimal-tuning PID control, frequency-domain optimal-tuning PID control and multiobjective optimal-tuning PID control. These schemes can provide optimal PID parameters even in case where the process dynamics are time variant. They are applied to three industrial systems: a hydraulic position control system, a rotary hydraulic speed control system and a gasifier.

Transmission Line Modelling of a Hydraulic Position Control System

The transmission line modelling (TLM) method is briefly discussed, showing how lumped dynamic components can be represented by equivalent lines. A hydraulic position control system was modelled by the TLM method, requiring mechanical and fluid transmission line models and a special ‘integrator’ line. The theoretical responses to step inputs are compared with experimental ones. Good agreement is shown.

Limit Cycle Prediction Conditions for a Class of Hydraulic Control System

This paper presents the conditions necessary to sustain a limit cycle in hydraulic position control systems with displacement feedback. The limit cycle performance of the system is then examined when the temperature of the working fluid varies between 283K(10°C) to 343K(70°C). Results are presented for an electrohydraulic system driving a load comprising inertia, viscous friction, and coulomb friction.