Hydraulic Subsystems Research Articles

Architecture Modeling and Test of Tractor Power Shift Transmission

Architecture modeling, simulation, and test verification are performed to meet the requirements of multi-domain modeling and simulation of tractor power shift transmission (PST). The principles of architecture modeling and high level architecture (HLA) are analyzed, and the PST architecture modeling connotation and simulation system structure are studied. Then the dynamic principles of PST mechanical, hydraulic and control subsystems are analyzed in the preparation phase, sliding friction phase and holding phase of clutch engagement. To build the PST system simulation model, the simulation models and components of the three subsystems are established, and the object and interaction classes of the simulation object model (SOM) for each component are defined. After that, the parameter mapping relationship between the components is analyzed, the interfaces between the simulation components and HLA are encapsulated, and the simulation component running sequence is analyzed. Finally, the PST clutch engagement law under tractor shift conditions is simulated and tested. The relative error and correlation coefficient between the simulated and test data of shift solenoid valve drive current are used as indexes to evaluate the PST system simulation model. The results show that the simulated drive current curves are consistent with the test ones. The maximum error between the simulated and test shift time appears at the third gear downshift point, with a value of 7.89%, and the minimum correlation coefficient value between the simulated and the test drive current at all shift points is 0.92, which indicate that the PST system simulation model is effective and accurate.

Design of a Robust Adaptive Controller for a Hydraulic Press and Experimental Validation

This article aims to illustrate the design and validation of an adaptive controller developed for a hydraulic press. The controller architecture relies on an inner/outer loop structure, with an outer loop devoted to the control of the mechanical part and the inner one of the hydraulic subsystem. Moreover, adaptive laws aiming to estimate/compensate for external forces and disturbances that occur during the pressing phase and for leakage flow in the piston are present. This second estimate is used to maintain the performances acceptable in a wide set of operative conditions and for predictive maintenance. By using singular perturbation arguments, we show robustness to slowly increasing leakage gains, a typical situation in a real-world application. The control scheme is validated both on a simulative Simscape model and the real hydraulic axis.

The Dynamic Performance Analysis of a Low-Floor Tram Hydraulic Anti-Kink System Based on Multidisciplinary Collaboration

According to the basic principle of the hydraulic anti-kink system and flow continuity equation, this paper takes the low-floor tram as the research object and the four vehicles as the research carrier. Based on the correlation parameters between the vehicle subsystem and the hydraulic subsystem, a co-simulation platform of a low-floor tram with hydraulic an anti-kink system is built. The co-simulation results show that the anti-kink system can well maintain the relative yaw angle consistency between the vehicle body and bogie. The anti-kink system restrains the maximum yaw angle and excessive lateral displacement of the vehicle body effectively. The consistency between the experiment results and the simulation results shows the accuracy of the model. The co-simulation model of the low-floor tram with hydraulic anti-kink system can be used to research the dynamic performance when it passes through curve line.

Kinematics Analysis and Trajectory Planning of the Working Device for Hydraulic Excavators

Robotization has become a research hotspot in the field of excavation machinery. In this paper, the excavator working device is regarded as the open-chain 4 DOF manipulator. The link coordinate system is established by D-H method, and forward kinematics from the configuration space to the joint space is analysed. Moreover, inverse kinematics and the mapping relationship between the joint space and the driving space are solved by geometric approach. The manipulator kinematics model is developed based on MATLAB Robotics Toolbox. Meanwhile, the point cloud image of the workspace for the excavator working device is plotted by the Latin hypercube sampling, and the complete working sequence for the excavator is planned and simulated. To verify the effect of trajectory planning, a multi-physics domain fusion model including the mechanical kinematics model, the hydraulic subsystem and the trajectory tracking control strategy was implemented by hybrid modeling method in MATLAB. At the same time, this work also presents a theoretical reference for the research of the motion trajectory for the excavator working device.

Semi-analytical modeling of transient rate behaviour of a horizontal well with multistage fractures in tight formations considering stress-sensitive effect

Stress-sensitive permeability imposes a significant impact on production performance in a tight formation; however, the widely used models assume the constant permeability or same stress-sensitive level for different systems, resulting in incorrect prediction of production rate and reservoir properties. In this work, theoretical models have been formulated, validated, and used to characterize the transient rate behaviour of a horizontal well with multistage fractures at constant wellbore pressure in tight formations by taking the different stress-sensitive effects in matrix and fracture subsystems into account. More specifically, a matrix-fracture fluid flow model with considering stress-sensitive effect was developed, during which the resulting nonlinear governing equation caused by stress-sensitive matrix permeability was weakened and linearized by using the Pedrosa's transform formulation and perturbation technique, respectively. Then, a slab source function was developed to obtain the solution for such a linearized problem in the Laplace domain. Meanwhile, a semi-analytical method is applied to solve the matrix-fracture flow models by discretizing each hydraulic fracture into small segments. Furthermore, the Blasingame type curves are generated to examine the stress-sensitive effects. In particular, stress-sensitivity in matrix and hydraulic fracture subsystems can be respectively analyzed. It is found that stress-sensitive permeability in either the matrix subsystem or the fracture subsystem has its negative influence on production rate. Such an influence is increased as the permeability modulus in matrix and fractures is increased. The matrix permeability modulus mainly decreases the production rate in the intermediate and late flow period, while its effect on the early time production rate is relatively small compared with other flow periods. Stress-sensitivity in fractures mainly affects the early time production rate and imposes a negligible impact on production rate during the intermediate and late period. The production rate is increased with an increase in the initial fracture conductivity. The dominant flow which contributes to the majority of the total production gradually shifts from the near-wellbore fracture segments to the near-tip fracture segments for the intermediate and high conductive fracture cases, while, for the low conductive fractures, the near-wellbore fluid flow is dominant for the entire period. Due to the inherent constraints in a tight formation, rate transient analysis is found to be more physically representative for accurately describing performance of a horizontal well with multistage fractures compared to the traditional pressure transient testing.

Fuzzy expert analysis of the severity of mining machinery failure

Mining machinery failure is almost an everyday occurrence. Usually the failures bare certain consequences, which require additional financial costs to repair and restore the system to its operational state. The consequences are viewed through negative and damaging effects a failure has on the machine, health and safety of the employees, work environment, and on the environment. The removal of the consequences of the failure requires additional financial investment, which has a negative impact on the company’s business. In order to prevent this, it is necessary to have Risk Centered Maintenance, where the risk assessment would include all the negative consequences of the risky event. The fuzzy expert assessment is presented in this paper, as well as the failure severity assessment based on the harmful effects of the failure. The negative effects of the machine component failure, such as the time needed for the repair, the possibility of workplace injury caused by the failure, and the impact it has on the environment, are analyzed in this paper as well. This approach to the severity of failure assessment enables a more comprehensive view of this risk indicator. It also enables the risk indicator “severity of failure” to gain greater significance in combination with other risk indicators. The developed model was presented on the example of typical failures of the hydraulic subsystems of a mobile crushing machine Lokotrack LT 1213S.

Influence of mill modulus control gain on vibration in hot rolling mills

The rolling mill vibration is characterized by the coupling effects among mechanical, electrical, hydraulic and interfacial subsystems. The influence of the mill modulus control gain in automatic gauge control on the vibration in hot rolling mills was investigated. Firstly, an experiment related to the mill modulus control gain was carried out in the hot rolling mill process, and it was found that the rolling mill vibration increases with the mill modulus control gain. Then, based on the Sims rolling force method, the coupling dynamic model was established to explain this phenomenon. Finally, the influence of mill modulus control gain on the vibration was analyzed numerically on the basis of the coupling dynamic model. Moreover, the agreement between the experimental results and the simulation results was confirmed and the measure reducing the mill modulus control gain was obtained to relieve mill vibration.

Pitch Stability Analysis for Mechanical-Hydraulic-Structural-Fluid Coupling System of High-Lift Hoist Vertical Shiplift

Pitch stability of the high-lift wire rope hoist vertical shiplift under dynamic hydraulic levelling has always been an issue of concern. It not only affects working efficiency but also brings significant challenges to operational safety. A new mechanical-hydraulic-structural-fluid (MHSF) coupling dynamics model and a developed semi-analytical method are presented for stable property analysis. The models of the hydraulic levelling subsystem, shallow water sloshing subsystem, the main hoist mechanical subsystem, and the shiplift chamber structure subsystem are built using a closed-loop transfer function, multi-modal theory, and an second-type Lagrangian equation, respectively. Then, a core twenty-one order state matrix of the MHSF coupling system is established using the state-space method. Subsequently, the Lyapunov motion stability theory and Eigen-analysis method are used in combination to judge the pitch stability and analyse the characteristics of the subsystems. Taking four typical high-lift hoist vertical shiplifts as examples, the rationality of the proposed model and method is validated. The results indicate that although the pitch stability safety factor under hydraulic dynamic levelling is reduced by about 15 % to 44 % with respect to hydraulic static levelling, hydraulic dynamic levelling still can meet stability requirements. Furthermore, for the designed 200 m level hoist vertical shiplift, the preliminary design parameters can ensure the pitch stability safety factor under dynamic hydraulic levelling of not less than 1.1. The element most prone to instability is the shallow water sloshing subsystem; increasing the synchronous shaft stiffness or the water boundary layer damping ratio can effectively enhance the pitch stability.

Thermal and efficiency improvements of all vanadium redox flow battery with novel main-side-tank system and slow pump shutdown

Abstract All vanadium redox flow battery is an important energy storage system with the advantages of flexible structure design, large energy storage scale, deep charge and discharge. In the present work, a system model of all vanadium redox flow battery is firstly established including thermal subsystem, electric subsystem and hydraulic subsystem, and the thermal behavior during both charging-discharging and standby phase is investigated. A novel method of main-side-tank system combined with slow pump shutdown is proposed to suppress the undesired temperature rise by reducing the stack state of charge (SOC) at the early standby phase and pre-charge the all vanadium redox flow battery system by cycling electrolyte from the charged stack to the uncharged side-tanks, and then improves the thermal performance and system efficiency. Based on this method, different side-tank volume proportion VP and shutdown time Δt are considered. Results show that the main-side-tank system with VP = 1 and Δt = 200 s has the maximum system efficiency improvement of 1.51%, and limits the battery temperature under 27.5 °C in a 2-days-cycle. For the specific efficiency improvement and specific temperature drop, the main-side-tank system with VP = 0.2 and shutdown time Δt = 180 s is the most economical case with the efficiency improvement of 1.20% and battery temperature limitation under 31.1 °C.

Design of a Nonlinear Predictive Controller for a Fractional-Order Hydraulic Turbine Governing System with Mechanical Time Delay

A nonlinear predictive control method for a fractional-order hydraulic turbine governing system (HTGS) with a time delay is studied in this paper. First, a fractional-order model of a time-delay hydraulic turbine governing system is presented. Second, the fractional-order hydraulic servo subsystem is transformed into a standard controlled autoregressive moving average (CARMA) model according to the Grünwald-Letnikov (G-L) definition of fractional calculus. Third, based on the delayed Takagi-Sugeno fuzzy model, the fuzzy prediction model of the integer-order part of the HTGS is given. Then, by introducing a fourth-order Runge-Kutta algorithm, the fuzzy prediction model can be easily transformed into the CARMA model. Furthermore, a nonlinear predictive controller is proposed to stabilize the time-delay HTGS. Finally, the experiment results are consistent with the theoretical analysis.

Imitating modeling results of a recuperative hydraulic subsystem of the timber truck manipulator

The relevance of improving the efficiency of a timber truck used for timber transportation due to the use of a recuperative hydraulic drive in its design is substantiated. The analysis is made of the use of recuperative hydraulic drives of technological machines with mechanisms for the recovery of kinetic energy of rotation and potential energy of lowering the load. A mathematical and, based on it, simulation model has been developed for the hydraulic subsystem of the manipulator of a timber truck, including mechanisms of boom, handle and column recuperation that have also been developed. Dependencies are obtained that make it possible to determine the maximum amount of recuperated energy for one loading cycle by changing the volume of the pneumohydraulic accumulator, the height of the assortment, and the time of one loading cycle.

Web-based virtual reality for simulation of a heavy manipulator with a freely suspended payload

The paper presents the development of a Web-based Virtual Reality (VR) environment for simulation and visualization of the motion of a hydraulically driven heavy manipulator with a freely suspended payload. Two main problems are resolved in the paper. First, a combined mathematical model of the manipulator, considered as a 2 DOF discrete mechanical model is derived. It represents the dynamics of the two key functional subsystems of the manipulator – mechanical subsystem, consisting of a link and freely suspended payload and hydraulic subsystem, consisting of a hydraulic cylinder. Second, by the use of the contemporary Web technologies a VR environment for simulation, visualization and animation of the obtained results is developed. The produced VR environment is easy reused and shared with other users and thus considerably facilitates the design, investigation, and e-learning of such type of system.

Energy analysis and optimization design of vehicle electro-hydraulic compound steering system

In order to reduce the vehicle steering energy consumption and improve the steering road feeling, this work proposes an electro-hydraulic compound steering (EHCS) system, which combines the functions of electric power steering (EPS) and electro-hydraulic power steering (EHPS). For this novel steering system, there is a complex mechanical-electro-hydraulic coupling relationship that affects the steering performance. Thus, how to choose the appropriate parameters to ensure the system of good energy-saving characteristics and steering road feeling is one of the key issues. The power flow of mechanical, electrical and hydraulic subsystems is used to test the coupling relationship between the parameters of the motor, hydraulic pipe, hydraulic valve, power cylinder, and mechanical steering structure, and analyze their influence on the steering energy consumption. According to the results of energy consumption sensitivity analysis, the main coupling parameters are selected as design variables, and the steering energy consumption, steering road feeling and steering wheel return error are taken as optimization objectives. To add population diversity and accelerate convergence velocity, the improved competitive multi-objective particle swarm optimization (CMOPSO) algorithm is proposed and used for optimization. The optimization results illustrate that the CMOPSO has better convergence compared with the basic MOPSO, and the EHCS system optimized by CMOPSO has a better steering economy, with better steering road feeling and smaller steering wheel return error. To verify the comprehensive steering performance, the optimized EHCS system is installed on the vehicle for an on-field road test. Compared with original EHPS, the road test results show that the energy consumption of the modified vehicle under the steering condition significantly decreases, and can also meet the steering assistance and driver road feeling requirements. Furthermore, the real road traffic scene around Nanjing University of Aeronautics and Astronautics is reconstructed to analyze the relationship between the whole vehicle energy consumption and energy characteristics of the EHCS system in the intelligent traffic environments, which verifies the steering energy consumption is reduced by 51.7% under the 15 km test road.

A general class of additive semiparametric models for recurrent event data

Recurrent event data is a special case of multivariate lifetime data that is present in a large variety of studies from numerous disciplines. Due to its pervasiveness, it is essential that appropriate models and inference procedures exist for its analysis. We propose a general class of additive semiparametric models for examining recurrent event data that uses an effective age process to take into account the impact of interventions applied to units after an event occurrence. The effect of covariates is additive instead of the common multiplicative assumption. We derive estimators of the regression parameter, baseline cumulative hazard function, and baseline survival function. We also establish the asymptotic properties of the estimators using tools from empirical process theory. Simulation studies indicate that the asymptotic properties of the regression parameter closely approximate its finite sample properties. The analysis of a real data set consisting of indolent lymphoma recurrence times provides a practical illustration of the class of models and is used to examine the impact of the effective age process. The importance of the effective age process is also demonstrated via the modeling of a data set of failure times for the hydraulic subsystems of load–haul–dump machines used in mining.

THE ELECTRIC DRIVE PUMPING UNITS STEADY OPERATING MODES OPTIMIZATION BY THE MODES RELIABILITY CRITERIAS

According to the research results, the target functions of the task of optimizing the functioning of the units according to the criteria of the regime reliability, depending on the flow of the working fluid were synthesized, which made it possible to research the influence of the regime on the reliability of operation of electric and hydraulic subsystems of the pump unit. The extreme weight of local target functions of regime reliability of electric motor and the centrifugal pump in various (especially low-flow rate) operating modes are determined. It is proposed to optimize the operating modes of pumping units of oil pumping station with the simultaneous use of the reliability criteria of electric drive and centrifugal pump. . It was established that the maximum values of reliability of electric drive and centrifugal pump are achieved at different values of the load, which requires the involvement of multi-criteria optimization methods. The problem of optimization of the established modes of the pump unit in the multicriteria setting, taking into account the technological limitations of its subsystems was formalized. The analysis of modern methods of solving the problem of multicriteria optimization of the steady modes of operation of pump units is carried out. The method of solving the multicriterion optimization problem is substantiated, which fully takes into account the influence of operation mode on the reliability of electric and hydraulic subsystems of pumping unit. It is revealed that the most appropriate method for solving this problem is the method of approaching an ideal (utopian) point in the criteria space. With this method, the desired ratio of criteria at the optimum point is the best. The value of the "agreed optimum" of liquid flow has been determined in order to choose the optimum for the reliability of operation mode of the pumping unit of oil pumping station.

Modelling failures times with dependent renewal type models via exchangeability

ABSTRACTFailure times of a machinery cannot always be assumed independent and identically distributed, eg, if after reparations the machinery is not restored to a same-as-new condition. Framed within the renewal processes approach, a generalization that considers exchangeable inter-arrival times is presented. The resulting model provides a more realistic approach to capture the dependence among events occurring at random times, while retaining much of the tractability of the classical renewal process. Extensions of some classical results and special cases of renewal functions are analysed, in particular, the one corresponding to an exchangeable sequence driven by a Dirichlet process. The proposal is tested through an estimation procedure using simulated data sets and with an application to the reliability of hydraulic subsystems in load-haul-dump machines.

Dynamic simulation on vibration control of marching tank gun based on adaptive robust control

In order to better understand the dynamic behavior and decrease the muzzle vibration of marching tank, a mechanical–electrical–hydraulic integrated dynamic model of marching tank was established based on a novel dynamic co-simulation method. The hydraulic system model was modeled in Amesim and the dynamic model of marching tank was established in RecurDyn based on multi-body system theory, vehicle terramechanics, and gun launch dynamics. The control system model was modeled in MATLAB/Simulink. Therein, the adaptive robust control algorithm was introduced to design the vertical stabilizer controller and the simulation program of the designed controller was developed by C language. The simulation results show that the muzzle vibration of marching tank can be controlled effectively by the ARC method. Furthermore, the muzzle error compensation signal was added in the designed controller to weaken the detrimental effect of the barrel flexibility on muzzle vibration. This work provides an approach to investigate the dynamic behavior of marching tank considering effects among the mechanical, hydraulic, and control subsystems.

A novel large-scale three-dimensional apparatus to study mechanisms of coal and gas outburst

Coal and gas outburst disasters affect safe production from coal mines. There has been limited progress in understanding and predicting these outbursts in the past years. Therefore, a novel large scale three-dimensional simulation experimental apparatus to study mechanisms of coal and gas outburst was developed. The experimental apparatus has dimensions of 1.5 m × 0.8 m × 0.8 m and can achieve a gas seal of 6 MPa. Its hydraulic sub-system can perform axial (3000 t) and horizontal symmetric (2000 t) loading. The outburst port can be initiated actively and instantaneously, similar to the sudden excitation of an outburst. The apparatus realizes the roadway network simulation of various fluid migration routes, resistance characteristics, and ventilation facilities. Simultaneously, 90 test channels and a sampling frequency of up to 4 Ms/s can be used to monitor the time–space distribution law of multiple parameters in the apparatus and realize the real-time observation of the experimental phenomena. The experimental apparatus can be used to simulate the entire process of the coal and gas outburst, including accumulation, motivation, development, and termination stages as well as systematically study the features and mechanisms of the outburst. A complete simulation experiment of an outburst under a high geo-stress was performed. The distribution and variation of the gas pressure and geo-stress before, during, and after the outburst were analyzed. The distribution of the outburst-pulverized coal and gas concentration rule was obtained, which shows the characteristics of the extrusion type. This experiment validates the capability and reliability of the newly developed coal and gas outburst simulation apparatus.

Coupled Dynamic Simulation of Two Stage Variable Compression Ratio (VCR) Connecting Rod Using Virtual Dynamics

<div class="section abstract"><div class="htmlview paragraph">The fuel consumption of combustion engines requires continuous reduction to meet future CO2 fleet targets. The progression of emission legislations shifted the focus on PN and NOX emissions in real world driving scenarios (RDE). Recently, the monitoring of CO emissions puts high load fuel enrichment for component protection into focus and a ban on enrichment is widely expected. Hence, gasoline engine technologies, which enable Lambda 1 operation in the entire engine map are specifically promoted. Variable Compression Ratio (VCR) attacks all these topics already at the combustion process. In addition to the well-known CO2 capability, VCR also enables enlargement of the lambda 1 operation in gasoline engines as well as reduced NOX emissions in diesel engines. The basic principle of developed VCR solution is to change the effective length of the connecting rod (and thereby the compression ratio) in two stages by several millimeters. Basically, the VCR connecting rod consists of a mechanical and hydraulic system which is fed with oil by the connecting rod bearing. All functional elements to realize the variability such as an eccentric, lever, support rods, check valves and shift valve are integrated into the connecting rod. The system works without “external” energy supply but uses mass- and gas forces - acting on the piston pin - to vary its length. In order to analyze and optimize the system dynamics, a highly sophisticated simulation approach based on coupled simulations of the mechanical and the hydraulic subsystem of the VCR connecting rod. The co-simulation is carried out in time domain using the commercial software Virtual Dynamics for the elastic multi body simulations and GT-Suite for 1D fluid simulations. In this article the coupled 3D-multi body simulation/1D-hydraulic co-simulation as used to optimize the VCR connecting rod performance are presented.</div></div>

Characterization of a pediatric rotary blood pump

Abstract Introduction A ventricular assist device (VAD) is an electromechanical pump used to treat heart failures. For designing the physiological control system for a VAD, one needs a mathematical model and its related parameters. This paper presents a characterization procedure for determining the model parameter values of the electrical, mechanical, and hydraulic subsystems of a pediatric Rotary Blood Pump (pRBP). Methods An in vitro test setup consisting of a pRBP prototype, a motor driver module, an acrylic reservoir, mechanical resistance and tubings, pressure and fluid flow sensors, and data acquisition, processing, and visualization system. The proposed procedure requires a set of experimental tests, and a parameter estimation algorithm for determining the model parameters values. Results The operating limits of the pRBP were identified from the steady-state data. The relationship between the pressure head, flow rate, and the rotational speed of the pRBP was found from the static tests. For the electrical and mechanical subsystems, the dc motor model has a viscous friction coefficient that varies nonlinearly with the flow. For the hydraulic subsystem, the pressure head is assumed to be a sum of terms related to the resistance, the inertance, the friction coefficient, and the pump speed. Conclusion The proposed methodology was successfully applied to the characterization of the pRBP. The combined use of static and dynamic tests provided a precise lumped parameter model for representing the pRBP dynamics. The agreement, regarding mean squared deviation, between experimental and simulated results demonstrates the correctness and feasibility of the characterization procedure.