CONTROL STRATEGY FOR ELECTRO-HYDRAULIC POSITION SERVO SYSTEM WITH GENERALIZED PULSE CODE MODULATION

A hybrid control strategy has been designed and developed for the electro-hydraulic posi-tion servo control system with generalized Pulse code modulation （GPCM）, which is suitable for the area where the work condition is poor and a large flow rate is required. It is difficult to control the GPCM system because the system is discrete. With consideration of the stability and speediness of the GPCM position servo control system, a control strategy is developed through the theoretical and ex-perimental analyses. The control strategy integrates the merits of Bang-Bang control, PID control and fuzzy control. With this hybrid control strategy, the electro hydraulic control system has good per-formances, and the servo control is carried out with GPCM through on-off valves.

Indirect Vector Control of Linear Induction Motors Using Space Vector Pulse Width Modulation

Vector control schemes have recently been used to drive linear induction motors(LIM)in high-performance applications.This trend promotes the development of precise and efficient control schemes for individual motors.This research aims to present a novel framework for speed and thrust force control of LIM using space vector pulse width modulation(SVPWM)inverters.The framework under consideration is developed in four stages.To begin,MATLAB Simulink was used to develop a detailed mathematical and electromechanical dynamicmodel.The research presents a modified SVPWM inverter control scheme.By tuning the proportional-integral(PI)controller with a transfer function,optimized values for the PI controller are derived.All the subsystems mentioned above are integrated to create a robust simulation of the LIM’s precise speed and thrust force control scheme.The reference speed values were chosen to evaluate the performance of the respective system,and the developed system’s response was verified using various data sets.For the low-speed range,a reference value of 10m/s is used,while a reference value of 100 m/s is used for the high-speed range.The speed output response indicates that themotor reached reference speed in amatter of seconds,as the delay time is between 8 and 10 s.The maximum amplitude of thrust achieved is less than 400N,demonstrating the controller’s capability to control a high-speed LIM with minimal thrust ripple.Due to the controlled speed range,the developed system is highly recommended for low-speed and high-speed and heavy-duty traction applications.

Fuzzy Feedback Control for Electro-Hydraulic Actuators

Electro-hydraulic actuators(EHA)have recently played a significant role in modern industrial applications,especially in systems requiring extremely high precision.This can be explained by EHA’s ability to precisely control the position and force through advanced sensors and innovative control algorithms.One of the promising approaches to improve control accuracy for EHA systems is applying classical to modern control algorithms,in which the proportional–inte-gral–derivative(PID)algorithm,fuzzy logic controller,and a hybrid of these methods are popular options.In this paper,we developed a novel version of the fuzzy control algorithm and linear feedback control method,namely fuzzy lin-ear feedback control,to improve the control performance.To achieve the highest performance,wefirst designed a mathematical EHA model based on the Matlab/Simulink software packages thanks to the selected parameters,which are similar to a real EHA system.Then,we respectively applied PID,fuzzy PID(FPID),and fuzzy linear feedback control(FLFC)before comparing them to have a full view of the outstanding advantages of the proposed algorithm.The simulation results showed that the proposed FLFC algorithm is approximately 99%and 77%super-ior in performance to the PID and feedback control algorithms,respectively.

Hamiltonian Reduction of Quantum Systems Controlled by Pulses

We explores Hamiltonian reduction in pulse-controlled finite-dimensional quantum systems with near-degenerate eigenstates. A quantum system with a non-degenerate ground state and several near-degenerate excited states is controlled by a short pulse, and the objective is to maximize the collective population on all excited states when we treat all of them as one level. Two cases of the systems are shown to be equivalent to effective two-level systems. When the pulse is weak, simple relations between the original systems and the reduced systems are obtained. When the pulse is strong, these relations are still available for pulses with only one frequency under the first-order approximation.

Fuzzy PID control system for hose pulse experiment based on LabVIEW

The hose pulse testing bench generally uses electro-hydraulic servo system. It occupies little space, tracks signals fast and has simple structure, and therefore it is widely used in industrial control field. However, there are lots of problems such as little accuracy and instability caused by slow response of hydraulic and various interference factors. Simple proportional integra- tion derivatiation （PID） control method of traditional pulse bench is simple in principle, but it is difficult in parameter adjust- ment. According to the special requirements of the control system, a PID method based on fuzzy control is proposed in the pa- per. This method not only retains the advantages of the conventional control system, but also ameliorates the drawbacks of parameter uncertainty, instability and lag. It has been testified that the method is practicable and can improve the precision and adaptation.

An improved ISR-WV rumor propagation model based on multichannels with time delay and pulse vaccination

The rapid development of the Internet has broadened the channels of dissemination of information,it has also led to the rapid and widespread propagation of rumors,which can have a serious negative impact socially.In this paper,an improved ISR-WV rumor propagation model integrating multichannels is proposed by considering the system’s time delay,and the influence of different channels of propagation on the dynamic process is further analyzed.Moreover,the basic reproduction number R0,rumor-free equilibrium,and rumor-prevailing equilibrium,as well as their stability,are deduced.Then,an optimal control problem with pulse vaccination is designed.Finally,the validity of the model and theoretical results is verified by numerical simulations and a practical application.The results show that the rumor propagation threshold R0 is more sensitive to the rate of the propagation of the information base channel.The shorter the thinking timeτ_(1)required for the ignorant to react after obtaining the information,the larger the final scale of propagation.Under this condition,the time delayτ_(2)spent by a spreader in producing a video is negatively related to the final scale of the propagation;conversely,a longerτ_(1)implies that the person tends to more cognizant,which can suppress the spread of rumors.Under this condition,τ_(2)has little effect on the final scale of propagation.In addition,the results also prove that timely implementation of the pulse vaccination control strategy of popular science education can effectively control the propagation of rumors and reduce their negative impact.

PID Controller Optimization by GA and Its Performances on the Electro-hydraulic Servo Control System

A proportional integral derivative （PID） controller is designed and attached to electro-hydraulic servo actuator system （EHSAS） to control the angular position of the rotary actuator which control the movable surface of space vehicles. The PID gain parameters are optimized by the genetic algorithm （GA）. The controller is verified on the new state-space model of servo-valves attached to the physical rotary actuator by SIMULINK program. The controller and the state-space model are verified experimentally. Simulation and experimental results verify the effectiveness of the PID controller adaptive by GA to control the angular position of the rotary actuator as compared with the classical PID controller and the compensator controller.

Fuzzy iterative learning control of electro-hydraulic servo system for SRM direct-drive volume control hydraulic press

A new kind of volume control hydraulic press that combines the advantages of both hydraulic and SRM(switched reluctance motor) driving technology is developed.Considering that the serious dead zone and time-variant nonlinearity exist in the volume control electro-hydraulic servo system,the ILC(iterative learning control) method is applied to tracking the displacement curve of the hydraulic press slider.In order to improve the convergence speed and precision of ILC,a fuzzy ILC algorithm that utilizes the fuzzy strategy to adaptively adjust the iterative learning gains is put forward.The simulation and experimental researches are carried out to investigate the convergence speed and precision of the fuzzy ILC for hydraulic press slider position tracking.The results show that the fuzzy ILC can raise the iterative learning speed enormously,and realize the tracking control of slider displacement curve with rapid response speed and high control precision.In experiment,the maximum tracking error 0.02 V is achieved through 12 iterations only.

Separate Control of High Frequency Electro-hydraulic Vibration Exciter

The working frequency of the conventional electro-hydraulic vibration exciters,which consist of a servo valve and a hydraulic cylinder,is generally restricted within a narrow range due to limited frequency response capability of the servo valve itself.To counteract such restriction,a novel scheme for an electro-hydraulic vibrator,controlled by a two-dimensional valve（2D valve） and a bias valve in parallel,is therefore proposed.The frequency,amplitude and offset are independently controlled by rotary speed,axial sliding of the spool of the 2D valve and axial sliding of the spool of the bias valve.The principle of separate control was presented and the regulation approach of frequency,amplitude and offset was discussed.A mathematical model of the hydraulic power mechanism for the proposed vibration exciter was established to investigate the relationship between the amplitude and the axial sliding of the 2D valve＇ spool,as well as that between the offset and the axial sliding of the bias valve＇s spool at various frequencies.An experimental system was built to validate the theoretical analysis.It is verified that the 2D exciter is capable of working smoothly in a frequency range of 5- 200 Hz.And its frequency,amplitude and offset can be controlled respectively by either closed loop or open loop method.There is a linear relationship between the output amplitude and the spool axial opening of the 2D valve until a point when the flow rate becomes saturate and the amplitude remains constant.The offset displacement of the cylinder＇s piston is linearly proportional to the axial displacement of the spool of the bias valve,when the valve opening is less than 25%.Thereafter,the slop of the offset curve decreases and tends to saturate.The proposed electro-hydraulic vibration controlled by the 2D valve not only facilitates the realization of high-frequency electro-hydraulic vibration,the high-accuracy of vibration can also be achieved by means of independent controls to the frequency,amplitude and offset.

Present Status and Prospect of High-Frequency Electro-hydraulic Vibration Control Technology

Electro-hydraulic vibration equipment(EHVE)is widely used in vibration environment simulation tests,such as vehicles,weapons,ships,aerospace,nuclear industries and seismic waves replication,etc.,due to its large output power,displacement and thrust,as well as good workload adaptation and multi-controllable parameters.Based on the domestic and overseas development of high-frequency EHVE,dividing them into servo-valve controlled vibration equipment and rotary-valve controlled vibration equipment.The research status and progress of high-frequency electro-hydraulic vibration control technology(EHVCT)are discussed,from the perspective of vibration waveform control and vibration controller.The problems of current electro-hydraulic vibration system bandwidth and waveform distortion control,stability control,offset control and complex vibration waveform generation in high-frequency vibration conditions are pointed out.Combining the existing rotary-valve controlled high-frequency electro-hydraulic vibration method,a new twin-valve independently controlled high-frequency electro-hydraulic vibration method is proposed to break through the limitations of current electro-hydraulic vibration technology in terms of system frequency bandwidth and waveform distortion.The new method can realize independent adjustment and control of vibration waveform frequency,amplitude and offset under high-frequency vibration conditions,and provide a new idea for accurate simulation of high-frequency vibration waveform.

Realizing precision pulse TIG welding with arc length control and visual image sensing based weld detection

Methods of arc length control and visual image based weld detection for precision pulse TIG welding were investigated. With a particular all hardware circuit, arc voltage during peak current stage is sampled and integrated to indicate arc length, deviation of arc length and adjusting parameters are calculated and output to drive a step motor directly. According to the features of welding image grabbed with CCD camera, a special algorithm was developed to detect the central line of weld fast and accurately. Then an application system were established, whose static arc length error is ±0.1 mm with 20 A average current and 1 mm given arc length, static detection precision of weld is 0.01 mm , processing time of each image is less than 120 ms . Precision pulse TIG welding of some given thin stainless steel components with complicated curved surface was successfully realized.

The design and artificial realization of a controller of pulse coupling feedback

In this paper a controller of pulse coupling feedback （PCF） is designed to control chaotic systems. Control principles and the technique to select the feedback coefficients are introduced. This controller is theoretically studied with a three dimensional （3D） chaotic system. The artificial simulation results show that the chaotic system can be stabilized to different periodic orbits by using the PCF method, and the number of the periodic orbits are 2^n×3^m p （n and m are integers）. Therefore, this control method is effective and practical.

Control of the photoionization/photodissociation processes of cyclopentanone with trains of femtosecond laser pulses

A train of three equally spaced femtosecond laser pulses is employed to control the photoionization/photodissociation processes of cyclopentanone. With the increase of pulse separation, a strong modulation of product ion yield is observed. More than ten-fold changes of ion yield ratio between different products can be realized. The experimental observations further explain the compositions and formation pathways of peaks in the mass spectra. The controlling mechanisms are also discussed.

Modeling, Simulation and Control of Pulsed DE-GMA Welding Process for Joining of Aluminum to Steel

Joining of aluminum to steel has attracted significant attention from the welding research community,automotive and rail transportation industries.Many current welding methods have been developed and applied,however,they can not precisely control the heat input to work-piece,they are high costs,low efficiency and consist lots of complex welding devices,and the generated intermetallic compound layer in weld bead interface is thicker.A novel pulsed double electrode gas metal arc welding（Pulsed DE-GMAW）method is developed.To achieve a stable welding process for joining of aluminum to steel,a mathematical model of coupled arc is established,and a new control scheme that uses the average feedback arc voltage of main loop to adjust the wire feed speed to control coupled arc length is proposed and developed.Then,the impulse control simulation of coupled arc length,wire feed speed and wire extension is conducted to demonstrate the mathematical model and predict the stability of welding process by changing the distance of contact tip to work-piece（CTWD）.To prove the proposed PSO based PID control scheme’s feasibility,the rapid prototyping experimental system is setup and the bead-on-plate control experiments are conducted to join aluminum to steel.The impulse control simulation shows that the established model can accurately represent the variation of coupled arc length,wire feed speed and the average main arc voltage when the welding process is disturbed,and the developed controller has a faster response and adjustment,only runs about 0.1 s.The captured electric signals show the main arc voltage gradually closes to the supposed arc voltage by adjusting the wire feed speed in 0.8 s.The obtained typical current waveform demonstrates that the main current can be reduced by controlling the bypass current under maintaining a relative large total current.The control experiment proves the accuracy of proposed model and feasibility of new control scheme further.The beautiful and smooth weld beads are also obtained by this method.Pulsed DE-GMAW can thus be considered as an alternative method for low cost,high efficiency joining of aluminum to steel.

Compensation for secondary uncertainty in electro-hydraulic servo system by gain adaptive sliding mode variable structure control

Based on consideration of the differential relations between the immeasurable variables and measurable variables in electro-hydraulic servo system,adaptive dynamic recurrent fuzzy neural networks(ADRFNNs) were employed to identify the primary uncertainty and the mathematic model of the system was turned into an equivalent linear model with terms of secondary uncertainty.At the same time,gain adaptive sliding mode variable structure control(GASMVSC) was employed to synthesize the control effort.The results show that the unrealization problem caused by some system's immeasurable state variables in traditional fuzzy neural networks(TFNN) taking all state variables as its inputs is overcome.On the other hand,the identification by the ADRFNNs online with high accuracy and the adaptive function of the correction term's gain in the GASMVSC make the system possess strong robustness and improved steady accuracy,and the chattering phenomenon of the control effort is also suppressed effectively.

Barrier Lyapunov functions-based dynamic surface control with tracking error constraints for ammunition manipulator electro-hydraulic system

This paper focuses on the dynamic tracking control of ammunition manipulator system. A standard state space model for the ammunition manipulator electro-hydraulic system(AMEHS) with inherent nonlinearities and uncertainties considered was established. To simultaneously suppress the violation of tracking error constraints and the complexity of differential explosion, a barrier Lyapunov functionsbased dynamic surface control(BLF-DSC) method was proposed for the position tracking control of the ammunition manipulator. Theoretical analysis prove the stability of the closed-loop overall system and the tracking error converges to a prescribed neighborhood asymptotically. The effectiveness and dynamic tracking performance of the proposed control strategy is validated via simulation and experimental results.

Femtosecond strong-field coherent control of nonresonant ionization with shaped pulses

The strong-field coherent control of the nonresonant ionization of nitrous oxide using shaped pulses is investigated.We study the dependence of periodic coherent oscillation of the total ionization yield on the variation of laser phase parameters. The physical mechanism of the strong-field coherent control is investigated experimentally and theoretically by the nonresonant spectral phase interferences in the frequency domain. We show that the intense shaped pulses with broadband and off-resonance can be used as a robust strong-field coherent control method.

Pressure-tracking control of a novel electro-hydraulic braking system considering friction compensation

This work presents an integrated pressure-tracking controller for a novel electro-hydraulic brake(EHB) system considering friction and hydraulic disturbances. To this end, a mathematical model of an EHB system, consisting of actuator and hydraulic sub-systems, is derived for describing the fundamental dynamics of the system and designing the controller. Due to sensor inaccuracy and measurement noise, a Kalman filter is constructed to estimate push rod stroke for generating desired master cylinder pressure. To improve pressure-tracking accuracy, a linear friction model is generated by linearizing the nonlinear Tustin friction model, and the unmodeled friction disturbances are assumed unknown but bounded. A sliding mode controller is designed for compensating friction disturbances, and the stability of the controller is investigated using the Lyapunov method. The performance of the proposed integrated controller is evaluated with a hardware-in-the-loop(HIL) test platform equipped with the EHB prototype. The test results demonstrate that the EHB system with the proposed integrated controller not only achieves good pressure-tracking performance, but also maintains robustness to friction disturbances.

Digital pulsed MIG welding machine based on adaptive fuzzy controller

Digital pulsed metal inert gas welding machine with double closed-loop control mode is designed and implemented. It realizes precision control for real time energy and demonstrates the flexibility of digital control. Test results of design prototype show that the designed control strategy can effectively adapt to the change of arc length and achieve ideal droplet transfer via one drop per pulse mode. Thus the welding process is stable and the weld bead is good.

High precise control method for a new type of Piezoelectric electro-hydraulic servo valve

A new type of piezoelectric electro-hydraulic servo valve system was proposed. And then multilayer piezoelectric actuator based on new piezoelectric ceramic material was used as the electricity-machine converter of the proposed piezoelectric electro-hydraulic servo valve. The proposed piezoelectric electro-hydraulic servo valve has ascendant performance compared with conventional ones. But the system is of high nonlinearity and uncertainty, it cannot achieve favorable control performance by conventional control method. To develop an efficient way to control piezoelectric electro-hydraulic servo valve system, a high-precise fuzzy control method with hysteresis nonlinear model in feedforward loop was proposed. The control method is separated into two parts: a feedforward loop with Preisach hysteresis nonlinear model and a feedback loop with high-precise fuzzy control. Experimental results show that the hysteresis loop and the maximum output hysteresis by the PID control method are 4.22% and 2.11 μm, respectively; the hysteresis loop and the maximum output hysteresis by the proposed control method respectively are 0.74% and 0.37 μm, respectively; the maximum tracking error by the PID control method for sine wave reference signal is about 5.02%, the maximum tracking error by the proposed control method for sine wave reference signal is about 0.85%.