The current research of master cylinder pressure estimation mainly relies on hydraulic characteristic or vehicle dynamics.But they are not independently applicable to any environment and have their own scope of applic...The current research of master cylinder pressure estimation mainly relies on hydraulic characteristic or vehicle dynamics.But they are not independently applicable to any environment and have their own scope of application.In addition,about the master cylinder pressure control,there are few studies that can simultaneously balance pressure building accuracy,speed,and prevent pressure overshoot and jitter.In this paper,an adaptative fusion method based on electro-hydraulic characteristic and vehicle mode is proposed to estimate the master cylinder pressure.The fusion strategy is mainly based on the prediction performance of two algorithms under different vehicle speeds,pressures,and ABS states.Apart from this,this article also includes real-time prediction of the friction model based on RLS to improve the accuracy of the electro-hydraulic mode.In order to simultaneously balance pressure control accuracy,response speed,and prevent overshoot and jitter,this article proposes an adaptative LQR controller for MC pressure control which uses fuzzy-logic controller to adjust the weights of LQR controller based on target pressure and difference compared with actual pressure.Through mode-in-loop and hardware-in-loop tests in ramp,step and sinusoidal response,the whole estimation and control system is verified based on real hydraulic system and the performance is satisfactory under these scenes.This research proposes an adaptative pressure estimation and control architecture for integrated electro-hydraulic brake system which could eliminate pressure sensors in typical scenarios and ensure the comprehensive performance of pressure control.展开更多
The hydraulic caliper disc brake system with air-over-oil is widely adopted at present for heavy vehicles,which makes use of air pressure system propelling the hydraulic pressure system acting on friction plates divid...The hydraulic caliper disc brake system with air-over-oil is widely adopted at present for heavy vehicles,which makes use of air pressure system propelling the hydraulic pressure system acting on friction plates divided and combined for braking.There are some disadvantages such as pneumatic components failure,dust polluted and produce lots of heat in hydraulic caliper disc brake system.Moreover,considering the demands of the high speed,heavy weight,heavy load and fast brake of heavy vehicles,the full power hydraulic brake system based on double pipelines for heavy vehicles is designed and analyzed in this paper.The scheme of the full power hydraulic brake system,in which the triloculare cylinder is controlled by dual brake valve,is adopted in the brake system.The full power hydraulic brake system can accomplish steering brake,parking brake and emergent brake for heavy vehicles.Furthermore,electronic control system that is responsible for coordinating the work of hydraulic decelerator and hydraulic brake system is developed for different speed brakes.Based on the analysis of the influence of composed unit and connecting pipeline on braking performance,the nonlinear mathematic model is established for the full power hydraulic brake system.The braking completion time and braking pressure in braking performance of the double-pipeline steering brake and parking brake are discussed by means of simulation experiments based on Matlab/Simulink,and the simulation results prove that the braking performance of steering brake and parking brake meets the designing requirement of the full power hydraulic brake system.Moreover,the test-bed experiments of the brake system for heavy vehicles are carried out.The experimental data prove that the braking performance achieves the goal of the design,and that the full power hydraulic brake system based on double pipelines can effectively enhance braking performance,ensure braking reliability and security for heavy vehicles.展开更多
Traditional hydraulic brake systems require a complex system of pipelines between an aircraft engine driven pump（EDP） and brake actuators, which increases the weight of the aircraft and may even cause serious vibrat...Traditional hydraulic brake systems require a complex system of pipelines between an aircraft engine driven pump（EDP） and brake actuators, which increases the weight of the aircraft and may even cause serious vibration and leakage problems. In order to improve the reliability and safety of more electric aircraft（MEA）, this paper proposes a new integrated self-powered brake system（ISBS） for MEA. It uses a hydraulic pump geared to the main wheel to recover a small part of the kinetic energy of a landing aircraft. The recovered energy then serves as the hydraulic power supply for brake actuators. It does not require additional hydraulic source, thus removing the pipelines between an EDP and brake actuators. In addition, its self-powered characteristic makes it possible to brake as usual even in an emergency situation when the airborne power is lost. This paper introduces the working principle of the ISBS and presents a prototype. The mathematical models of a taxiing aircraft and the ISBS are established. A feedback linearization control algorithm is designed to fulfill the anti-skid control. Simulations are carried out to verify the feasibility of the ISBS, and experiments are conducted on a ground inertia brake test bench. The ISBS presents a good performance and provides a new potential solution in the field of brake systems for MEA.展开更多
Air brake systems are critical equipment for railway trains, which affects the running safety of the trains significantly. To study air braking characteristics of long freight trains, an approach for simulating air br...Air brake systems are critical equipment for railway trains, which affects the running safety of the trains significantly. To study air braking characteristics of long freight trains, an approach for simulating air brake systems based on fuid dynamics theory was proposed. The structures and working mechanisms of locomotive and wagon air brakes are introduced, and mathematical models of the pipes, brake valves, reservoirs or chambers, cylinders, etc., are presented.Besides, the dynamic motions of parts in the main valve are considered. The simulation model of the whole air brake system is then formulated, and the solving method based on the finite-difference method is used. New efficient pipe boundary conditions without iterations are developed for brake pipes and branch pipes, which can achieve higher computational efficiency. The proposed approach for simulating the air brake system is validated by comparing with published measured data. Simulation results of different train formations indicate that models that consider the dynamic behavior of brake pipes are recommended for predicting the characteristics of long trains under service braking conditions.展开更多
With the rapid development of China's social economy, the number of car ownership increases year by year, the number of road traffic accidents is also high. In order to deal with each major traffic accident scient...With the rapid development of China's social economy, the number of car ownership increases year by year, the number of road traffic accidents is also high. In order to deal with each major traffic accident scientifically and effectively and clarify the responsibility of the accident, vehicle performance appraisal is particularly important. In order to clarify the influence of vehicles in traffic accidents and ensure the identification of accident liability, it is necessary to evaluate their related performance. In this paper, the braking identification as the entry point, the related theories and technologies involved are discussed, hoping to give some inspiration to the relevant personnel.展开更多
Advanced driver-assistance systems such as Honda’s collision mitigation brake system(CMBS)can help achieve traffic safety.In this paper,the naturalistic driving study and a series of simulations are combined to bette...Advanced driver-assistance systems such as Honda’s collision mitigation brake system(CMBS)can help achieve traffic safety.In this paper,the naturalistic driving study and a series of simulations are combined to better evaluate the performance of the CMBS in the Chinese traffic environment.First,because safety-critical situations can be diverse especially in the Chinese environment,the Chinese traffic-accident characteristics are analyzed according to accident statistics over the past 17 years.Next,10 Chinese traffic-accident scenarios accounting for more than 80%of traffic accidents are selected.For each typical scenario,353 representative cases are collected from the traffic-management department of Beijing.These real-world accident cases are then reconstructed by the traffic-accident-reconstruction software PC-Crash on the basis of accident-scene diagrams.This study also proposes a systematic analytical process for estimating the effectiveness of the technology using the co-simulation platform of PC-Crash and rateEFFECT,in which 176 simulations are analyzed in detail to assess the accident-avoidance performance of the CMBS.The overall collision-avoidance effectiveness reaches 82.4%,showing that the proposed approach is efficient for avoiding collisions,thereby enhancing traffic safety and improving traffic management.展开更多
This paper puts forward the LPM fault diagnosis method in the view of the important purpose of on-line monitoring and fault diagnosis for hoister brake system. The feasibility of the two diagnosis methods are proved i...This paper puts forward the LPM fault diagnosis method in the view of the important purpose of on-line monitoring and fault diagnosis for hoister brake system. The feasibility of the two diagnosis methods are proved in theories; two methods are proved about feasibility and reliability through testing. Two methods are manifestoed that they can undertake the on-line monitoring and fault diagnosis for hoister brake system with satisfied effect.展开更多
Compared to the current eddy braking patterns using a single magnetic source,hybrid excitation rail eddy brakes have many advantages,such as controllability,energy saving,and various operating models.Considering the l...Compared to the current eddy braking patterns using a single magnetic source,hybrid excitation rail eddy brakes have many advantages,such as controllability,energy saving,and various operating models.Considering the large braking power consumption of the high-speed train,a hybrid excitation rail eddy brake system,which is based on the principle of electromagnetic field,is proposed to fulfill the needs of safety and reliability.Then the working processes of the mechanical lifting system and electromagnetic system are demonstrated.With the electromagnetic system analyzed using the finite element method,the factors such as speed,air gap,and exciting current have influences on the braking force and attractive force.At last,the structure optimization of the brake system is discussed.展开更多
To evaluate the software behavior of the electronic control unit （ECU） of automotive electrical parking brake （EPB）, a software- in-the-loop （SiL） simulation system is built. The EPB is simulated by ARX （auto-r...To evaluate the software behavior of the electronic control unit （ECU） of automotive electrical parking brake （EPB）, a software- in-the-loop （SiL） simulation system is built. The EPB is simulated by ARX （auto-regressive with auxiliary input） model, ARMAX （auto-regressive moving average with auxiliary input） model, and NNARMAX （neural network ARMAX） model. By system identification, the ARX（3,4,2）, ARX（4,4,2）, ARMAX（3,3,1,1）, and ARMAX（4,4,3,2） models are derived. Validation results show that the four-order ARMAX model and the NNARMAX model better simulate the actuator of the EPB.展开更多
In this paper,the problem of brake orbits with minimal period estimates are considered for the first-order Hamiltonian systems with anisotropic growth,i.e.,the Hamiltonian functions may have super-quadratic,sub-quadra...In this paper,the problem of brake orbits with minimal period estimates are considered for the first-order Hamiltonian systems with anisotropic growth,i.e.,the Hamiltonian functions may have super-quadratic,sub-quadratic and quadratic behaviors simultaneously in different variable components.展开更多
In the context of the“dual carbon”goals,to address issues such as high energy consumption,high costs,and low power quality in the rapid development of electrified railways,this study focused on the China Railways Hi...In the context of the“dual carbon”goals,to address issues such as high energy consumption,high costs,and low power quality in the rapid development of electrified railways,this study focused on the China Railways High-Speed 5 Electric Multiple Unit and proposed a mathematical model and capacity optimization method for an onboard energy storage system using lithium batteries and supercapacitors as storage media.Firstly,considering the electrical characteristics,weight,and volume of the storage media,a mathematical model of the energy storage system was established.Secondly,to tackle problems related to energy consumption and power quality,an energy management strategy was proposed that comprehensively considers peak shaving and valley filling and power quality by controlling the charge/discharge thresholds of the storage system.Thecapacity optimization adopted a bilevel programming model,with the series/parallel number of storage modules as variables,considering constraints imposed by the Direct Current to Direct Current converter,train load,and space.An improved Particle Swarm Optimization algorithm and linear programming solver were used to solve specific cases.The results show that the proposed onboard energy storage system can effectively achieve energy savings,reduce consumption,and improve power qualitywhile meeting the load and space limitations of the train.展开更多
As Model-Based Systems Engineering(MBSE)was applied to the Electric Multiple Unit(EMU)braking system control logic,a preliminary exploration was conducted for bullet train braking system control logic research using a...As Model-Based Systems Engineering(MBSE)was applied to the Electric Multiple Unit(EMU)braking system control logic,a preliminary exploration was conducted for bullet train braking system control logic research using an MBSE practice framework.The framework mainly includes the requirement analysis phase,functional analysis phase,and design phase.Systems Modeling Language(SysML)was used as the modeling language,and Cameo Systems Modeler(CSM)was employed as the modeling tool.By integrating the EMU braking system control logic and utilizing a top-down design approach,the implementation of MBSE in the bullet train braking system was analyzed and studied.The results show that,according to the MBSE practice framework,a unified description of the requirement analysis,functional analysis,and design synthesis of the EMU braking system control logic can be achieved.Additionally,the correlation and traceability between models can be established.展开更多
Brake wear particle(BWP)emissions are considered one of the dominant sources of particulate matter pollution in urban environments.BWP emissions have increased significantly under high-temperature conditions,emerging ...Brake wear particle(BWP)emissions are considered one of the dominant sources of particulate matter pollution in urban environments.BWP emissions have increased significantly under high-temperature conditions,emerging as a focal point of research interest.This study investigates the effect of brake temperatures on BWP emissions.The brake pad materials undergo violent decomposition and oxidation reactions and generate large amounts of incompletely oxidized organic products at temperatures above 475℃.These organic products cause particles below 200 nm to proliferate,and nanoparticles below 40 nm account for the largest contribution of total BWPs.When the friction surface temperature exceeds 475℃,the high-concentration BWPs below 200 nm will agglomerate into larger particles.High temperatures also cause the brake pad surface to delaminate and fragment into particles above 2.5μm.In addition,when the initial brake speed is above 160 km/h,or the brake pressure is above 7 bar,there is a sharp increase in particles below 200 nm.The results suggest that a significant number of nanoparticles below 40 nm are inferred to be generated as the flash temperature of the friction surface reaches the violent reaction temperature.This study provides guidelines for designing low-emission brake pads,as improving the high-temperature resistance of brake pad material components possibly reduces BWP generation.展开更多
In ground vehicles, the brake is an essential system to ensure the safety of movement. Multiple braking mechanisms have been introduced for use in vehicles. This study explores the potential of using magneto-rheologic...In ground vehicles, the brake is an essential system to ensure the safety of movement. Multiple braking mechanisms have been introduced for use in vehicles. This study explores the potential of using magneto-rheological fluid (MRF) brakes in automotive applications. MRF brakes offer controllable braking force due to a magnetic field, but their use is limited by simulation challenges. In this study, a 7-tooth MRF brake model is proposed. The brake model is simulated in Altair Flux software to analyze magnetic field distribution, braking torque, and its variation under different currents and disc speeds. The simulation conditions also consider both viscous and electromagnetic torque components. Then, the results are analyzed across different brake regions, including rotor, stator, and fluid gap. These results provide valuable insights for designing, manufacturing, installing, and testing MRF brakes for automotive use.展开更多
The regenerative braking energy utilization system(RBEUS)stands as a promising technique for improving the efficiency and power quality of electrified railways.Beyond the vital aspects of energy management and control...The regenerative braking energy utilization system(RBEUS)stands as a promising technique for improving the efficiency and power quality of electrified railways.Beyond the vital aspects of energy management and control strategies,ensuring fault protection is paramount for the secure and steady operation of the traction power supply system(TPSS)integrated with RBEUS.This paper introduces an innovative protection scheme tailored to diverse RBEUS application scenarios.Firstly,fault categories are streamlined into three levels:system,equipment,and warning.Subsequently,a novel multi-port active power differential protection method,aligned with RBEUS operational principles,is crafted to serve as a comprehensive and sensitive main protection.Building upon this foundation,a hierarchical protection structure for RBEUS is established,addressing the intricacies and variations in fault types while boosting anti-disturbance capabilities under faulty conditions.Embracing the principle of railway-oriented safety,a collaborative RBEUS-TPSS protection scheme is put forth.Finally,through simulated scenarios encompassing various fault conditions,the proposed scheme’s feasibility and effectiveness are convincingly validated.展开更多
In this study,a novel synergistic swing energy-regenerative hybrid system(SSEHS)for excavators with a large inertia slewing platform is constructed.With the SSEHS,the pressure boosting and output energy synergy of mul...In this study,a novel synergistic swing energy-regenerative hybrid system(SSEHS)for excavators with a large inertia slewing platform is constructed.With the SSEHS,the pressure boosting and output energy synergy of multiple energy sources can be realized,while the swing braking energy can be recovered and used by means of hydraulic energy.Additionally,considering the system constraints and comprehensive optimization conditions of energy efficiency and dynamic characteristics,an improved multi-objective particle swarm optimization(IMOPSO)combined with an adaptive grid is proposed for parameter optimization of the SSEHS.Meanwhile,a parameter rule-based control strategy is designed,which can switch to a reasonable working mode according to the real-time state.Finally,a physical prototype of a 50-t excavator and its AMESim model is established.The semi-simulation and semi-experiment results demonstrate that compared with a conventional swing system,energy consumption under the 90°rotation condition could be reduced by about 51.4%in the SSEHS before parameter optimization,while the energy-saving efficiency is improved by another 13.2%after parameter optimization.This confirms the effectiveness of the SSEHS and the IMOPSO parameter optimization method proposed in this paper.The IMOPSO algorithm is universal and can be used for parameter matching and optimization of hybrid power systems.展开更多
The aircraft braking system is critical to ensure the safe take-off and landing of the aircraft.However,the braking system is often exposed to high temperatures and strong vibration working environments,which makes th...The aircraft braking system is critical to ensure the safe take-off and landing of the aircraft.However,the braking system is often exposed to high temperatures and strong vibration working environments,which makes the sensor prone to failure.Sensor failure has the potential to compromise aircraft safety.In order to improve the safety of the aircraft braking system,a fault detection and fault-tolerant control(FDFTC)strategy for the aircraft brake pressure sensor is designed.Firstly,a model based on a bidirectional long short-term memory(Bi-LSTM)network is constructed to estimate the brake pressure.Then,the residual sequence is obtained by comparing the measured pressure with the estimated pressure.On this basis,the improved sequential probability ratio test(SPRT)method based on mathematical statistics is applied to analyze the residual sequence to detect the fault.Finally,simulation and hardware-in-the-loop(HIL)testing results indicate that the proposed FDFTC strategy can detect sensor faults in time and efficiently complete braking when faults occur.Hence,the proposed FDFTC strategy can effectively deal with the faults of the aircraft brake pressure sensor,which is of great significance to improve the reliability and safety of the aircraft.展开更多
Anti lock brake systems (ABS) are now widely used on motor vehicles. To reduce product cost and to use currently available technologies, standard ABS uses only wheel speed sensors to detect wheel angular velocities...Anti lock brake systems (ABS) are now widely used on motor vehicles. To reduce product cost and to use currently available technologies, standard ABS uses only wheel speed sensors to detect wheel angular velocities, which is not enough to directly obtain wheel slip ratios needed by the control unit, but can be used to calculate reference slip ratios with measured wheel angular velocities and the estimated vehicle speed. Therefore, the road friction coefficient, which determines the vehicle deceleration during severe braking, is an important parameter in estimating vehicle speed. This paper analyzes wheel acceleration responses in simulations of severe braking on different road surfaces and selects a pair of specific points to identify the wheel acceleration curve for each operating condition, such as road surface, pedal braking torque and wheel vertical load. It was found that the curve using the selected points for each road surface clearly differs from that of the other road surfaces. Therefore, different road surfaces can be distinguished with these selected points which represent their corresponding road surfaces. The analysis assumes that only wheel speed sensors are available as hardware and that the road cohesion condition can be determined in the initial part of the severe braking process.展开更多
Electrical Parking Brake(EPB) has been popularly used in passenger cars over the past ten years. With the help of the several kinds of sensors mounted in driveline for the total traction force estimation, EPB can obta...Electrical Parking Brake(EPB) has been popularly used in passenger cars over the past ten years. With the help of the several kinds of sensors mounted in driveline for the total traction force estimation, EPB can obtain well performance on drive-off assistance and automatic parking brake. Furthermore, its AUTOHOLD function can realize automatic parking brake and ease the driver. However, given that the higher cost and complexity of this traction force estimation method based on the driveline sensors and its slower response resulted by applying maximum parking force for safety parking while driving off, a novel automatic parking brake system without these transmission system sensors, such as clutch position sensor for the cars with manual transmission, is proposed in this paper, including its control scheme and application test. Firstly, the indirect judgement method of the appropriate moment to release the parking brake, which is based on the car pitch moment when it drives off, is introduced according to the force analysis when the car is ready to go. Then a pragmatic mass estimation method for proper brake force calculation is proposed for improving the drive-off performance. In addition, for the convenience and drivability of skillful driver, as well as the system reliability, a mechanical redundant design to reserve the conventional handbrake lever is also described. Finally, various simulations based on CarSim software and road tests are performed to validate its effectiveness.展开更多
The coefficient of friction(COF)is one of the most important parameters to evaluate the performance of a brake system.To design proper brake systems,it is important to know the COF when estimating the brake force and ...The coefficient of friction(COF)is one of the most important parameters to evaluate the performance of a brake system.To design proper brake systems,it is important to know the COF when estimating the brake force and resulting torque.It is challenging to simulate the COF since friction in disc brakes is a complex phenomenon that depends on several parameters such as sliding velocity,contact pressure,materials,and temperatures,etc.There is a lack of studies found in the literature focusing on simulation of the COF for a full brake system based on tribometer material characterization.The aim of this work is therefore to investigate the possibility to use a finite element analysis(FEA)approach combined with a COF pv-map to compute the global COF of a disc brake system.The local COF is determined from a pv-map for each local sliding velocity and contact pressure determined by the FEA.Knowing the local COF,the braking force of the entire brake system and the global COF can be evaluated.Results obtained by the simulation are compared with dyno bench test of the same brake system to investigate the validity of the simulation approach.Results show that the simulation is perfectly in line with the experimental measurements in terms of in-stop COF development,but slightly higher with a positive offset for every braking.展开更多
基金Supported by National Natural Science Foundation of China(Grant Nos.52202494,52202495)Chongqing Special Project for Technological Innovation and Application Development(Grant No.CSTB2022TIAD-DEX0014).
文摘The current research of master cylinder pressure estimation mainly relies on hydraulic characteristic or vehicle dynamics.But they are not independently applicable to any environment and have their own scope of application.In addition,about the master cylinder pressure control,there are few studies that can simultaneously balance pressure building accuracy,speed,and prevent pressure overshoot and jitter.In this paper,an adaptative fusion method based on electro-hydraulic characteristic and vehicle mode is proposed to estimate the master cylinder pressure.The fusion strategy is mainly based on the prediction performance of two algorithms under different vehicle speeds,pressures,and ABS states.Apart from this,this article also includes real-time prediction of the friction model based on RLS to improve the accuracy of the electro-hydraulic mode.In order to simultaneously balance pressure control accuracy,response speed,and prevent overshoot and jitter,this article proposes an adaptative LQR controller for MC pressure control which uses fuzzy-logic controller to adjust the weights of LQR controller based on target pressure and difference compared with actual pressure.Through mode-in-loop and hardware-in-loop tests in ramp,step and sinusoidal response,the whole estimation and control system is verified based on real hydraulic system and the performance is satisfactory under these scenes.This research proposes an adaptative pressure estimation and control architecture for integrated electro-hydraulic brake system which could eliminate pressure sensors in typical scenarios and ensure the comprehensive performance of pressure control.
基金supported by Basic Scientific Research Operation Cost of Central Universities of China (Grant No. 200903168)
文摘The hydraulic caliper disc brake system with air-over-oil is widely adopted at present for heavy vehicles,which makes use of air pressure system propelling the hydraulic pressure system acting on friction plates divided and combined for braking.There are some disadvantages such as pneumatic components failure,dust polluted and produce lots of heat in hydraulic caliper disc brake system.Moreover,considering the demands of the high speed,heavy weight,heavy load and fast brake of heavy vehicles,the full power hydraulic brake system based on double pipelines for heavy vehicles is designed and analyzed in this paper.The scheme of the full power hydraulic brake system,in which the triloculare cylinder is controlled by dual brake valve,is adopted in the brake system.The full power hydraulic brake system can accomplish steering brake,parking brake and emergent brake for heavy vehicles.Furthermore,electronic control system that is responsible for coordinating the work of hydraulic decelerator and hydraulic brake system is developed for different speed brakes.Based on the analysis of the influence of composed unit and connecting pipeline on braking performance,the nonlinear mathematic model is established for the full power hydraulic brake system.The braking completion time and braking pressure in braking performance of the double-pipeline steering brake and parking brake are discussed by means of simulation experiments based on Matlab/Simulink,and the simulation results prove that the braking performance of steering brake and parking brake meets the designing requirement of the full power hydraulic brake system.Moreover,the test-bed experiments of the brake system for heavy vehicles are carried out.The experimental data prove that the braking performance achieves the goal of the design,and that the full power hydraulic brake system based on double pipelines can effectively enhance braking performance,ensure braking reliability and security for heavy vehicles.
基金supports from the Science and Technology on Aircraft Control Laboratory and Aviation Key Laboratory of Scienceco-supported by the National Natural Science Foundation of China(No.51475020)the National Key Basic Research Program of China(No.2014CB046401)
文摘Traditional hydraulic brake systems require a complex system of pipelines between an aircraft engine driven pump（EDP） and brake actuators, which increases the weight of the aircraft and may even cause serious vibration and leakage problems. In order to improve the reliability and safety of more electric aircraft（MEA）, this paper proposes a new integrated self-powered brake system（ISBS） for MEA. It uses a hydraulic pump geared to the main wheel to recover a small part of the kinetic energy of a landing aircraft. The recovered energy then serves as the hydraulic power supply for brake actuators. It does not require additional hydraulic source, thus removing the pipelines between an EDP and brake actuators. In addition, its self-powered characteristic makes it possible to brake as usual even in an emergency situation when the airborne power is lost. This paper introduces the working principle of the ISBS and presents a prototype. The mathematical models of a taxiing aircraft and the ISBS are established. A feedback linearization control algorithm is designed to fulfill the anti-skid control. Simulations are carried out to verify the feasibility of the ISBS, and experiments are conducted on a ground inertia brake test bench. The ISBS presents a good performance and provides a new potential solution in the field of brake systems for MEA.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51825504, 51735012, and 52072317)
文摘Air brake systems are critical equipment for railway trains, which affects the running safety of the trains significantly. To study air braking characteristics of long freight trains, an approach for simulating air brake systems based on fuid dynamics theory was proposed. The structures and working mechanisms of locomotive and wagon air brakes are introduced, and mathematical models of the pipes, brake valves, reservoirs or chambers, cylinders, etc., are presented.Besides, the dynamic motions of parts in the main valve are considered. The simulation model of the whole air brake system is then formulated, and the solving method based on the finite-difference method is used. New efficient pipe boundary conditions without iterations are developed for brake pipes and branch pipes, which can achieve higher computational efficiency. The proposed approach for simulating the air brake system is validated by comparing with published measured data. Simulation results of different train formations indicate that models that consider the dynamic behavior of brake pipes are recommended for predicting the characteristics of long trains under service braking conditions.
文摘With the rapid development of China's social economy, the number of car ownership increases year by year, the number of road traffic accidents is also high. In order to deal with each major traffic accident scientifically and effectively and clarify the responsibility of the accident, vehicle performance appraisal is particularly important. In order to clarify the influence of vehicles in traffic accidents and ensure the identification of accident liability, it is necessary to evaluate their related performance. In this paper, the braking identification as the entry point, the related theories and technologies involved are discussed, hoping to give some inspiration to the relevant personnel.
基金Project(51625503) supported by the National Science Fund for Distinguished Young Scholars,ChinaProject(61790561) supported by the National Natural Science Foundation of China+1 种基金Project(20163000124) supported by Tsinghua-Honda Joint Research,ChinaProject(TTS2017-02) supported by the Open Fund for Jiangsu Key Laboratory of Traffic and Transportation Security,China
文摘Advanced driver-assistance systems such as Honda’s collision mitigation brake system(CMBS)can help achieve traffic safety.In this paper,the naturalistic driving study and a series of simulations are combined to better evaluate the performance of the CMBS in the Chinese traffic environment.First,because safety-critical situations can be diverse especially in the Chinese environment,the Chinese traffic-accident characteristics are analyzed according to accident statistics over the past 17 years.Next,10 Chinese traffic-accident scenarios accounting for more than 80%of traffic accidents are selected.For each typical scenario,353 representative cases are collected from the traffic-management department of Beijing.These real-world accident cases are then reconstructed by the traffic-accident-reconstruction software PC-Crash on the basis of accident-scene diagrams.This study also proposes a systematic analytical process for estimating the effectiveness of the technology using the co-simulation platform of PC-Crash and rateEFFECT,in which 176 simulations are analyzed in detail to assess the accident-avoidance performance of the CMBS.The overall collision-avoidance effectiveness reaches 82.4%,showing that the proposed approach is efficient for avoiding collisions,thereby enhancing traffic safety and improving traffic management.
文摘This paper puts forward the LPM fault diagnosis method in the view of the important purpose of on-line monitoring and fault diagnosis for hoister brake system. The feasibility of the two diagnosis methods are proved in theories; two methods are proved about feasibility and reliability through testing. Two methods are manifestoed that they can undertake the on-line monitoring and fault diagnosis for hoister brake system with satisfied effect.
基金Project supported by the National Natural Science Foundation of China(Nos.50877070 and 51105331)the Special Financial Grant from the China Postdoctoral Science Foundation(Nos.201104720 and 201104721)
文摘Compared to the current eddy braking patterns using a single magnetic source,hybrid excitation rail eddy brakes have many advantages,such as controllability,energy saving,and various operating models.Considering the large braking power consumption of the high-speed train,a hybrid excitation rail eddy brake system,which is based on the principle of electromagnetic field,is proposed to fulfill the needs of safety and reliability.Then the working processes of the mechanical lifting system and electromagnetic system are demonstrated.With the electromagnetic system analyzed using the finite element method,the factors such as speed,air gap,and exciting current have influences on the braking force and attractive force.At last,the structure optimization of the brake system is discussed.
基金Sichuan Province Key Discipline Con-struction for Automotive Engineering ( No.SZD0410 )Research Foundation of Xihua University (No.R0620301)
文摘To evaluate the software behavior of the electronic control unit （ECU） of automotive electrical parking brake （EPB）, a software- in-the-loop （SiL） simulation system is built. The EPB is simulated by ARX （auto-regressive with auxiliary input） model, ARMAX （auto-regressive moving average with auxiliary input） model, and NNARMAX （neural network ARMAX） model. By system identification, the ARX（3,4,2）, ARX（4,4,2）, ARMAX（3,3,1,1）, and ARMAX（4,4,3,2） models are derived. Validation results show that the four-order ARMAX model and the NNARMAX model better simulate the actuator of the EPB.
基金supported by the NSFC(12301138)the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(2021L377)+1 种基金the Doctoral Scientific Research Foundation of Shanxi Datong University(2018-B-15)The second author’s work was supported by the NSFC(12171108).
文摘In this paper,the problem of brake orbits with minimal period estimates are considered for the first-order Hamiltonian systems with anisotropic growth,i.e.,the Hamiltonian functions may have super-quadratic,sub-quadratic and quadratic behaviors simultaneously in different variable components.
基金funded by the National Natural Science Foundation of China(52167013)the Key Program of Natural Science Foundation of Gansu Province(24JRRA225)Natural Science Foundation of Gansu Province(23JRRA891).
文摘In the context of the“dual carbon”goals,to address issues such as high energy consumption,high costs,and low power quality in the rapid development of electrified railways,this study focused on the China Railways High-Speed 5 Electric Multiple Unit and proposed a mathematical model and capacity optimization method for an onboard energy storage system using lithium batteries and supercapacitors as storage media.Firstly,considering the electrical characteristics,weight,and volume of the storage media,a mathematical model of the energy storage system was established.Secondly,to tackle problems related to energy consumption and power quality,an energy management strategy was proposed that comprehensively considers peak shaving and valley filling and power quality by controlling the charge/discharge thresholds of the storage system.Thecapacity optimization adopted a bilevel programming model,with the series/parallel number of storage modules as variables,considering constraints imposed by the Direct Current to Direct Current converter,train load,and space.An improved Particle Swarm Optimization algorithm and linear programming solver were used to solve specific cases.The results show that the proposed onboard energy storage system can effectively achieve energy savings,reduce consumption,and improve power qualitywhile meeting the load and space limitations of the train.
文摘As Model-Based Systems Engineering(MBSE)was applied to the Electric Multiple Unit(EMU)braking system control logic,a preliminary exploration was conducted for bullet train braking system control logic research using an MBSE practice framework.The framework mainly includes the requirement analysis phase,functional analysis phase,and design phase.Systems Modeling Language(SysML)was used as the modeling language,and Cameo Systems Modeler(CSM)was employed as the modeling tool.By integrating the EMU braking system control logic and utilizing a top-down design approach,the implementation of MBSE in the bullet train braking system was analyzed and studied.The results show that,according to the MBSE practice framework,a unified description of the requirement analysis,functional analysis,and design synthesis of the EMU braking system control logic can be achieved.Additionally,the correlation and traceability between models can be established.
基金supported by the National Natural Science Foundation of China(Nos.52172337 and 52272342)the Postdoctoral Fellowship Program(Grade B)of China Postdoctoral Science Foundation(No.GZB20240352)the Shuimu Tsinghua Scholar Program of Tsinghua University(No.2023SM230)。
文摘Brake wear particle(BWP)emissions are considered one of the dominant sources of particulate matter pollution in urban environments.BWP emissions have increased significantly under high-temperature conditions,emerging as a focal point of research interest.This study investigates the effect of brake temperatures on BWP emissions.The brake pad materials undergo violent decomposition and oxidation reactions and generate large amounts of incompletely oxidized organic products at temperatures above 475℃.These organic products cause particles below 200 nm to proliferate,and nanoparticles below 40 nm account for the largest contribution of total BWPs.When the friction surface temperature exceeds 475℃,the high-concentration BWPs below 200 nm will agglomerate into larger particles.High temperatures also cause the brake pad surface to delaminate and fragment into particles above 2.5μm.In addition,when the initial brake speed is above 160 km/h,or the brake pressure is above 7 bar,there is a sharp increase in particles below 200 nm.The results suggest that a significant number of nanoparticles below 40 nm are inferred to be generated as the flash temperature of the friction surface reaches the violent reaction temperature.This study provides guidelines for designing low-emission brake pads,as improving the high-temperature resistance of brake pad material components possibly reduces BWP generation.
文摘In ground vehicles, the brake is an essential system to ensure the safety of movement. Multiple braking mechanisms have been introduced for use in vehicles. This study explores the potential of using magneto-rheological fluid (MRF) brakes in automotive applications. MRF brakes offer controllable braking force due to a magnetic field, but their use is limited by simulation challenges. In this study, a 7-tooth MRF brake model is proposed. The brake model is simulated in Altair Flux software to analyze magnetic field distribution, braking torque, and its variation under different currents and disc speeds. The simulation conditions also consider both viscous and electromagnetic torque components. Then, the results are analyzed across different brake regions, including rotor, stator, and fluid gap. These results provide valuable insights for designing, manufacturing, installing, and testing MRF brakes for automotive use.
基金supported by the National Natural Science Foundation of China(Nos.52107126 and52077179)the Key Regional Innovation and Development Joint Fund Project(No.2023YFB2303901)the funding of Chengdu Guojia Electrical Engineering Co.,Ltd.(No.NEEC-2022-B11).
文摘The regenerative braking energy utilization system(RBEUS)stands as a promising technique for improving the efficiency and power quality of electrified railways.Beyond the vital aspects of energy management and control strategies,ensuring fault protection is paramount for the secure and steady operation of the traction power supply system(TPSS)integrated with RBEUS.This paper introduces an innovative protection scheme tailored to diverse RBEUS application scenarios.Firstly,fault categories are streamlined into three levels:system,equipment,and warning.Subsequently,a novel multi-port active power differential protection method,aligned with RBEUS operational principles,is crafted to serve as a comprehensive and sensitive main protection.Building upon this foundation,a hierarchical protection structure for RBEUS is established,addressing the intricacies and variations in fault types while boosting anti-disturbance capabilities under faulty conditions.Embracing the principle of railway-oriented safety,a collaborative RBEUS-TPSS protection scheme is put forth.Finally,through simulated scenarios encompassing various fault conditions,the proposed scheme’s feasibility and effectiveness are convincingly validated.
基金supported by the Changsha Major Science and Technology Plan Project,China(No.kq2207002)the Natural Science Foundation of Hunan Province(No.2023JJ40720)the Postgraduate Innovative Project of Central South University,China(No.2022XQLH058)。
文摘In this study,a novel synergistic swing energy-regenerative hybrid system(SSEHS)for excavators with a large inertia slewing platform is constructed.With the SSEHS,the pressure boosting and output energy synergy of multiple energy sources can be realized,while the swing braking energy can be recovered and used by means of hydraulic energy.Additionally,considering the system constraints and comprehensive optimization conditions of energy efficiency and dynamic characteristics,an improved multi-objective particle swarm optimization(IMOPSO)combined with an adaptive grid is proposed for parameter optimization of the SSEHS.Meanwhile,a parameter rule-based control strategy is designed,which can switch to a reasonable working mode according to the real-time state.Finally,a physical prototype of a 50-t excavator and its AMESim model is established.The semi-simulation and semi-experiment results demonstrate that compared with a conventional swing system,energy consumption under the 90°rotation condition could be reduced by about 51.4%in the SSEHS before parameter optimization,while the energy-saving efficiency is improved by another 13.2%after parameter optimization.This confirms the effectiveness of the SSEHS and the IMOPSO parameter optimization method proposed in this paper.The IMOPSO algorithm is universal and can be used for parameter matching and optimization of hybrid power systems.
基金Supported by National Natural Science Foundation of China(Grant No.52205045)National Key Research and Development Program of China(Grant No.2021YFB2011300)+2 种基金Aeronautical Science Foundation of China(Grant No.2022Z029051001)Zhejiang Provincial Natural Science Foundation of China(Grant No.LZ24E050006)Research Fund of State Key Laboratory of Mechanics and Control for Aerospace Structures(Nanjing University of Aeronautics and Astronautics)(Grant No.MCAS-E-0224G01).
文摘The aircraft braking system is critical to ensure the safe take-off and landing of the aircraft.However,the braking system is often exposed to high temperatures and strong vibration working environments,which makes the sensor prone to failure.Sensor failure has the potential to compromise aircraft safety.In order to improve the safety of the aircraft braking system,a fault detection and fault-tolerant control(FDFTC)strategy for the aircraft brake pressure sensor is designed.Firstly,a model based on a bidirectional long short-term memory(Bi-LSTM)network is constructed to estimate the brake pressure.Then,the residual sequence is obtained by comparing the measured pressure with the estimated pressure.On this basis,the improved sequential probability ratio test(SPRT)method based on mathematical statistics is applied to analyze the residual sequence to detect the fault.Finally,simulation and hardware-in-the-loop(HIL)testing results indicate that the proposed FDFTC strategy can detect sensor faults in time and efficiently complete braking when faults occur.Hence,the proposed FDFTC strategy can effectively deal with the faults of the aircraft brake pressure sensor,which is of great significance to improve the reliability and safety of the aircraft.
基金the Major Research Project of the Ninth-Five Plan (1996 - 2 0 0 0 ) of China (No. 96 - A0 5 - 0 5 - 0 2 )
文摘Anti lock brake systems (ABS) are now widely used on motor vehicles. To reduce product cost and to use currently available technologies, standard ABS uses only wheel speed sensors to detect wheel angular velocities, which is not enough to directly obtain wheel slip ratios needed by the control unit, but can be used to calculate reference slip ratios with measured wheel angular velocities and the estimated vehicle speed. Therefore, the road friction coefficient, which determines the vehicle deceleration during severe braking, is an important parameter in estimating vehicle speed. This paper analyzes wheel acceleration responses in simulations of severe braking on different road surfaces and selects a pair of specific points to identify the wheel acceleration curve for each operating condition, such as road surface, pedal braking torque and wheel vertical load. It was found that the curve using the selected points for each road surface clearly differs from that of the other road surfaces. Therefore, different road surfaces can be distinguished with these selected points which represent their corresponding road surfaces. The analysis assumes that only wheel speed sensors are available as hardware and that the road cohesion condition can be determined in the initial part of the severe braking process.
基金supported by the National Natural Science Foundation of China(Grant No.51875235)the 2018 "13th Five-Year" Scientific Research Planning Project of the Education Department of Jilin Province(Grant No.JJKH20180135KJ)the 2018 Jilin Province Science and Technology Development Plan-International Science and Technology Cooperation Project(Grant No.20180414011GH)
文摘Electrical Parking Brake(EPB) has been popularly used in passenger cars over the past ten years. With the help of the several kinds of sensors mounted in driveline for the total traction force estimation, EPB can obtain well performance on drive-off assistance and automatic parking brake. Furthermore, its AUTOHOLD function can realize automatic parking brake and ease the driver. However, given that the higher cost and complexity of this traction force estimation method based on the driveline sensors and its slower response resulted by applying maximum parking force for safety parking while driving off, a novel automatic parking brake system without these transmission system sensors, such as clutch position sensor for the cars with manual transmission, is proposed in this paper, including its control scheme and application test. Firstly, the indirect judgement method of the appropriate moment to release the parking brake, which is based on the car pitch moment when it drives off, is introduced according to the force analysis when the car is ready to go. Then a pragmatic mass estimation method for proper brake force calculation is proposed for improving the drive-off performance. In addition, for the convenience and drivability of skillful driver, as well as the system reliability, a mechanical redundant design to reserve the conventional handbrake lever is also described. Finally, various simulations based on CarSim software and road tests are performed to validate its effectiveness.
文摘The coefficient of friction(COF)is one of the most important parameters to evaluate the performance of a brake system.To design proper brake systems,it is important to know the COF when estimating the brake force and resulting torque.It is challenging to simulate the COF since friction in disc brakes is a complex phenomenon that depends on several parameters such as sliding velocity,contact pressure,materials,and temperatures,etc.There is a lack of studies found in the literature focusing on simulation of the COF for a full brake system based on tribometer material characterization.The aim of this work is therefore to investigate the possibility to use a finite element analysis(FEA)approach combined with a COF pv-map to compute the global COF of a disc brake system.The local COF is determined from a pv-map for each local sliding velocity and contact pressure determined by the FEA.Knowing the local COF,the braking force of the entire brake system and the global COF can be evaluated.Results obtained by the simulation are compared with dyno bench test of the same brake system to investigate the validity of the simulation approach.Results show that the simulation is perfectly in line with the experimental measurements in terms of in-stop COF development,but slightly higher with a positive offset for every braking.
