To improve the semi-empirical model, the slip sinkage effect is analyzed based on the real vehicle test. A dynamic testing system is used to gain the dynamic responses of wheel-soil interactions, The Gauss-Newton algo...To improve the semi-empirical model, the slip sinkage effect is analyzed based on the real vehicle test. A dynamic testing system is used to gain the dynamic responses of wheel-soil interactions, The Gauss-Newton algorithm is adopted to estimate the undetermined parameters involved in the slip sinkage models. Wong＇s original model is compared with three typical slip sinkage models on the prediction performance of a drawbar pull. The maximum error rate, root mean squared error and correlation coefficient are utilized to evaluate the performance. The results indicate that the slip sinkage models outperform Wong＇s model and greatly improve the prediction accuracy. Lyasko＇s model is confirmed as an outstanding one for its comprehensive performance. Hence, the existence of the slip sinkage effect is validated. Lyasko＇s model is selected as an optimal one for the practical evaluation of military vehicle trafficability.展开更多
In present-day highly-automated vehicles,there are occasions when the driving system disengages and the human driver is required to take-over.This is of great importance to a vehicle's safety and ride comfort.In t...In present-day highly-automated vehicles,there are occasions when the driving system disengages and the human driver is required to take-over.This is of great importance to a vehicle's safety and ride comfort.In the U.S state of California,the Autonomous Vehicle Testing Regulations require every manufacturer testing autonomous vehicles on public roads to submit an annual report summarizing the disengagements of the technology experienced during testing.On 1 January 2016,seven manufacturers submitted their first disengagement reports:Bosch,Delphi,Google,Nissan,Mercedes-Benz,Volkswagen,and Tesla Motors.This work analyses the data from these disengagement reports with the aim of gaining abetter understanding of the situations in which a driver is required to takeover,as this is potentially useful in improving the Society of Automotive Engineers(SAE)Level 2 and Level 3 automation technologies.Disengagement events from testing are classified into different groups based on attributes and the causes of disengagement are investigated and compared in detail.The mechanisms and time taken for take-over transition occurred in disengagements are studied.Finally,recommendations for OEMs,manufacturers,and government organizations are also discussed.展开更多
Car fleets escorted by police along Chang’an Avenue are not a rare sight for Beijing residents, who are accustomed to the practice when leaders of foreign states visit the capital of China.
Special axle wheel for motor vehicle inspection is an indispensable special weighing instrument in the process of actual inspection of motor vehicles. This kind of detector belongs to non-automatic weighing instrument...Special axle wheel for motor vehicle inspection is an indispensable special weighing instrument in the process of actual inspection of motor vehicles. This kind of detector belongs to non-automatic weighing instrument, and certain problems will inevitably occur in the actual use process. At present, with the continuous improvement of social economy in our country, the production and ownership of automobiles are in the process of rapid development, and the safety performance of automobiles has also received increasing attention. However, the actual inspection of the axle wheel weight gauge is mainly to check whether the braking force of the motor vehicle can meet the corresponding standard, which plays a very important role in ensuring the safety performance of the whole vehicle. In recent years, relevant motor vehicle safety inspection agencies have used various inspection standards, from the initial GB 21861-2014, GB 7258-2017 safety inspection standard and GB 18565-2016 comprehensive inspection standard to the current revision of GB 3847-2018 and GB 18285-2018 environmental inspection standards. With the continuous revision of comprehensive inspection standards, the demand for talents of relevant motor vehicle safety inspection agencies is getting higher and higher. Only when the comprehensive ability of relevant staff is continuously improved, can they better deal with the inaccurate and unreliable inspection results of motor vehicle safety inspection agencies. Based on this, this paper studies the evaluation of measurement uncertainty of indication value of special axle (wheel) gravimeter for motor vehicle testing, for reference.展开更多
The theory of vehicle's correlation tests was discussed and the correlation test mathematical model was created. According to the damage theory, the correlation equation was brought up. The method to solove it was...The theory of vehicle's correlation tests was discussed and the correlation test mathematical model was created. According to the damage theory, the correlation equation was brought up. The method to solove it was given. The text gives the theory basis of vehicle's correlation tests. The results can be used to give the vehicle's test designation and to make the test to fit the actual environments. Besides that, the methods give acceleration and strengthen effects.展开更多
The LM-6 A new generation solid-liquid strap-on launch vehicle has the structural dynamic characteristics of lower frequencies,denser modes and coupling modes in longitudinal,bending and torsion modal space.During the...The LM-6 A new generation solid-liquid strap-on launch vehicle has the structural dynamic characteristics of lower frequencies,denser modes and coupling modes in longitudinal,bending and torsion modal space.During the development phase of LM-6 A,modal tests of partial stacks and the full vehicle were designed to obtain the structural dynamic properties.The structural dynamic models using the finite element method(FEM)have been verified and calibrated based on the modal test data.This paper describes the pre-test predictions and test execution,and details the comparison between the pre-test predictions and the test data.The successful maiden flight of LM-6 A further confirmed the effectiveness of structural dynamic modeling and modal test for LM-6 A.展开更多
Nowadays harmful gas in vehicle exhaust has pollute d air heavily. To prevent the environment from polluting, the request of emissions control legislation becomes more stringent. New legislation prescribes not only th...Nowadays harmful gas in vehicle exhaust has pollute d air heavily. To prevent the environment from polluting, the request of emissions control legislation becomes more stringent. New legislation prescribes not only the emissions limitation of vehicles, but also testing instruments and methods. Test car must be operated on the chassis dynamometer and data must be collect ed and analyzed with prescriptive exhaust analysis system as well. The mass of harmful exhaust gas, containing the concentration and volume of emis sion, which is independent from the model of automobile and engine, can be used as a criterion to evaluate the pollution of an automobile. Constant Volume Sampl e System (CVS) is used to measure vehicle emissions, but it is too expensive to apply extensively. The Vehicle Mass Analysis System(Vmas), a new vehicle exhaust mass analysis system produced in USA late 1990s,is used to test and analyze veh icle exhaust. As a test instrument, it has the virtue of cheapness and easy mana geability. In this paper, Vmas is used to measure the emissions of a light truck CA1020F. A ccording to 15 running modes of Vehicle Exhaust Legislation, the test car is ope rated on the chassis dynamometer and data are collected and analyzed with Vmas. The test results show that it is viable to measure and evaluate automobile emiss ion with Vmas. Most of HC exhaust is produced when the car is decelerating. The major factor that influences the mass of HC emission is the sudden decrease of e ngine load causing incomplete combustion in decelerating mode. Test results indi cate CO and NOx are mainly produced in the process of increasing load. The forme r reason is incomplete combustion and the latter is high burning temperature cau sed by the increasing load. The methods of reducing automobile emission are also discussed in this paper.展开更多
The accurate control for the vehicle height and leveling adjustment system of an electronic air suspension(EAS) still is a challenging problem that has not been effectively solved in prior researches. This paper propo...The accurate control for the vehicle height and leveling adjustment system of an electronic air suspension(EAS) still is a challenging problem that has not been effectively solved in prior researches. This paper proposes a new adaptive controller to control the vehicle height and to adjust the roll and pitch angles of the vehicle body(leveling control) during the vehicle height adjustment procedures by an EAS system. A nonlinear mechanism model of the full?car vehicle height adjustment system is established to reflect the system dynamic behaviors and to derive the system optimal control law. To deal with the nonlinear characters in the vehicle height and leveling adjustment processes, the nonlinear system model is globally linearized through the state feedback method. On this basis, a fuzzy sliding mode controller(FSMC) is designed to improve the control accuracy of the vehicle height adjustment and to reduce the peak values of the roll and pitch angles of the vehicle body. To verify the effectiveness of the proposed control method more accurately, the full?car EAS system model programmed using AMESim is also given. Then, the co?simulation study of the FSMC performance can be conducted. Finally, actual vehicle tests are performed with a city bus, and the test results illustrate that the vehicle height adjustment performance is effectively guaranteed by the FSMC, and the peak values of the roll and pitch angles of the vehicle body during the vehicle height adjustment procedures are also reduced significantly. This research proposes an effective control methodology for the vehicle height and leveling adjustment system of an EAS, which provides a favorable control performance for the system.展开更多
The deployment of autonomous vehicles is rapidly evolving,bringing both unprecedented opportunities and challenges.To achieve safer autonomous driving,the role of testing has become paramount,serving as the cornerston...The deployment of autonomous vehicles is rapidly evolving,bringing both unprecedented opportunities and challenges.To achieve safer autonomous driving,the role of testing has become paramount,serving as the cornerstone for validating the performance,robustness,and trustworthiness of autonomous driving systems.Unlike traditional vehicle testing,the focus of autonomous vehicle testing is on their intended driving functionality in complex driving environments.The burgeoning field of autonomous vehicle testing requires not only an understanding of current technological landscapes but also a proactive exploration of innovative solutions to advance the field,particularly through the application of artificial intelligence and simulation-based approaches.Within the spectrum of autonomous vehicle testing,the evolving challenges demand advancements in key technologies,including the construction and generalization of testing scenarios,the recognition of risky scenarios,driving behavior modeling,comprehensive testing evaluation,evidence-based testing protocols,simulation toolchain development,and more.展开更多
For the purpose of engineering development for a new 8-step speed automatic transmission,a simplified dynamic model for this gearbox was established and key parameters which affected the shift quality were analyzed.Ai...For the purpose of engineering development for a new 8-step speed automatic transmission,a simplified dynamic model for this gearbox was established and key parameters which affected the shift quality were analyzed.Aiming at four different shift types,the ideal characteristics of shift clutch and engine control were set up.By using torque estimation method,PI slip control algorithm and engine coordinated control principle,the control model and transmission controller were well developed for three shift phases which included rapid-fill phase,torque phase and inertia phase.The testing environment on the rig and prototype vehicle level was built and the testing results obtained in ultimate condition could verify the accuracy and feasibility of this shift control strategy.The peak jerk during shift process was controlled within ±2 g/s where the smooth gearshift was obtained.The development proposal and algorithm have a high value for engineering application.展开更多
With an advanced foreign hydraulic automatic transmission as the objective,an analytical method for the gear-shifting schedule is proposed.First the demanded maximum gradient of test is estimated.Then a test scheme an...With an advanced foreign hydraulic automatic transmission as the objective,an analytical method for the gear-shifting schedule is proposed.First the demanded maximum gradient of test is estimated.Then a test scheme and analytical procedure is formulated by initial test and hypothetical shift parameters.Finally through gear-shifting tests under different road conditions,load,accelerator pedal position limitation,throttle opening and output shaft speed are found to be the gear-shifting parameters.Under a common road condition,the gear-shifting schedule is a double-parameter schedule.Based on the driver＇s demands on braking and dynamic performance,different shift schedules are made under downhill,uphill and quick releasing acceleration pedal conditions.The operation criteria of down-shift schedule on abrupt grade are proposed.展开更多
Adverse weather conditions increase road risks;thus,weather testing is necessary to evaluate vehicle performance.Outdoor testing is the most realistic,but it is not as controlled,repeatable,and rapid as indoor testing...Adverse weather conditions increase road risks;thus,weather testing is necessary to evaluate vehicle performance.Outdoor testing is the most realistic,but it is not as controlled,repeatable,and rapid as indoor testing using an artificial precipitation system.However,outdoor data is still desirable for establishing the simulation targets on the vehicle surfaces.The dynamic-to-static precipitation intensity ratio is a useful parameter to correlate natural precipitation with perceived precipitation experienced by the moving vehicle.Theoretically,the amount of precipitation experienced by a translating surface depends on the orientation and travel speed.However,there are other external factors that could affect the perceived intensity,such as wind,turbulence,and droplet size distribution(DSD).Therefore,the existing simplified models evaluating a number of droplet strikes or precipitation flux calculated using natural precipitation density fail to have accurate predictions of the perceived precipitation rate,which hinders the evaluation vehicle application performance,such as sensor perception.In the present work,a semi-empirical prediction model is developed from the physics of precipitation in the context of vehicle aerodynamics and atmospheric dynamics.This model is validated with outdoor testing on a track for three days with rainy conditions.Multiple optical disdrometers are used to evaluate the precipitation rate experienced by a moving vehicle at different surface orientations through meteorological observations obtained in real-time from a nearby stationary meteorological tower and a moving vehicle.The data acquisition and processing methods are presented in detail.Results suggested that the proposed model is found to improve the current simplified mathematical expressions and is repeatable.It is found that improvements in prediction accuracy of perceived precipitation intensity compared to existing methods are usually more than 50%.展开更多
Safety testing is a crucial phase in the development of autonomous vehicles,with scenarios serving as the fundamental medium for these tests.The construction of scenarios that accurately reflect the real-world traffic...Safety testing is a crucial phase in the development of autonomous vehicles,with scenarios serving as the fundamental medium for these tests.The construction of scenarios that accurately reflect the real-world traffic behavior is a key challenge for autonomous vehicle testing technology,given the need for authenticity and effectiveness in testing.Addressing this,this study introduces a method for generating test scenarios specifically for intersections.This method involves decoupling the scenario into interactive and non-interactive layers.For the interactive elements,namely the traffic participants,this study proposes a novel approach to construct a human-like decision-making model adapted to intersections,with the OF-T-GAIL algorithm at its core.This algorithm,through a novel perception-decision representation and an omnidirectional coordinate system transformation,effectively reduces the cumulative error in the trajectory generation.Furthermore,this model is extended to multiple agents,allowing the bulk generation of intersection test scenario segments.These scenarios and the traffic participant(TP)models are validated using the SinD dataset,demonstrating the applicability and effectiveness of the approach in creating testing environments for autonomous driving systems.展开更多
An efficient method for helicopter rotor fault diagnosis was proposed using diagnostic matrix and its software framework was developed.The diagnostic matrix was extracted by the way of simulating the quantitative mode...An efficient method for helicopter rotor fault diagnosis was proposed using diagnostic matrix and its software framework was developed.The diagnostic matrix was extracted by the way of simulating the quantitative models of damaged and undamaged rotor systems.The conflicts were recognized by the virtual symptom sensor based on the dependencies between symptoms and faults.Diagnostic candidates were generated by the Boolean hitting algorithm.The proposed method provides multi-fault real-time diagnostic capability and it is suitable for the synthetic health monitoring of complex systems.展开更多
An accurate estimation of a vehicle’s state of motion is the basis of dynamic stability control.Two different nonlinear Kalman filters are adopted for the estimation of the vehicle’s lateral/rollover stability state...An accurate estimation of a vehicle’s state of motion is the basis of dynamic stability control.Two different nonlinear Kalman filters are adopted for the estimation of the vehicle’s lateral/rollover stability state.First,the overall structure of the state estimation with four inputs and four outputs is introduced.After determining tire-cornering stiffness using a recursive leastsquares(RLS)method,the equations of state and of observation for the nonlinear Kalman filter are established based on a vehicle model with four degrees of freedom including planar and rollover dynamics.Then,the specific steps of real-time state estimation using the extended Kalman filter(EKF)and unscented Kalman filter(UKF)are both given.In a co-simulation,we find that the RLS algorithm estimates tire-cornering stiffness accurately and quickly,and the UKF improves the effect of state estimation compared with EKF.In addition,the UKF is verified against data from vehicle tests.The results show the proposed method is reliable and practical in estimating vehicle states.展开更多
With the increasing level of automation of autonomous vehicles,it is important to conduct comprehensive and extensive testing before releasing autonomous vehicles into the market.Traditional public road and closed-fie...With the increasing level of automation of autonomous vehicles,it is important to conduct comprehensive and extensive testing before releasing autonomous vehicles into the market.Traditional public road and closed-field testing failed to meet the requirements of high testing efficiency and scenario coverage.Therefore,scenario-based autonomous vehicle simulation testing has emerged.Many scenarios form the basis of simulation testing.Generating additional scenarios from an existing scenario library is a significant problem.Taking the scenarios of a proceeding vehicle cutting into an adjacent lane on highways as an example,based on an autoencoder and a generative adversarial network(GAN),a method that combines Transformer to capture the features of a long-time series,called SceGAN,is proposed to model and generate scenarios of autonomous vehicles on highways.An evaluation system is established to analyze the reliability of SceGAN using discriminative and predictive scores and further evaluate the effect of scenario generation in terms of similarity and coverage.Experiments showed that compared with TimeGAN and AEGAN,SceGAN is superior in data fidelity and availability,and their similarity increased by 27.22%and 21.39%,respectively.The coverage increased from 79.84%to 93.98%as generated scenarios increased from 2,547 to 50,000,indicating that the proposed method has a strong generalization capability for generating multiple trajectories,providing a basis for generating test scenarios and promoting autonomous vehicle testing.展开更多
Unlike widely used ADAS test approaches based on predefined typical scenarios,a new ADAS test methodology has been proposed by the United Nations Economic Commission for Europe Regulation No.157(ECE R 157),which verif...Unlike widely used ADAS test approaches based on predefined typical scenarios,a new ADAS test methodology has been proposed by the United Nations Economic Commission for Europe Regulation No.157(ECE R 157),which verifies whether ADAS meet safety requirements by comparing them to driver performance models.However,whether the driver performance models in ECE R157 can be utilized to characterize driver behaviors in China has not been validated,which limits advancements of globally consistent ADAS test procedures.In order to compare human drivers with the cut-in performance model in ECE R157,51 cut-in cases from 65,000 km naturalistic driving data collected in China were applied to analyze response characteristics of following vehicle’s drivers in the cut-in scenario.The results can be summarized as follows.First of all,90%of the drivers release accelerators and 75%of the drivers brake before lane-changers reach lane lines,whereas the cut-in performance model in ECE R157 brakes about 0.95 s after lane-changers reach lane lines.This phenomenon can be explained by preview features of drivers.Secondly,some drivers release accelerators until they see clear lane-changing maneuvers,whereas some drivers anticipate possibilities of lane-changing very early and release accelerators in advance.Thirdly,time headway should be employed as a risk estimator in the cut-in scenario rather than time-to-collision.These results can help to calibrate parameters in the cut-in performance model of ECE R157 according to behaviors of Chinese drivers and increase the scope of application for the test methodology proposed in ECE R157.展开更多
In this work three fuel consumption and exhaust emission models,ADVISOR,VT-MICRO and the European Environmental Agency Emission factors,have been used to obtain fuel consumption(FC)and exhaust emissions.These models h...In this work three fuel consumption and exhaust emission models,ADVISOR,VT-MICRO and the European Environmental Agency Emission factors,have been used to obtain fuel consumption(FC)and exhaust emissions.These models have been used at micro-scale,using the two signal treatment methods presented.The manuscript presents:1)a methodology to collect data in real urban driving cycles,2)an estimation of FC and tailpipe emissions using some available models in literature,and 3)a novel analysis of the results based on delivered wheel power.The results include Fuel Consumption(FC),CO_(2),NO_(x) and PM_(10) emissions,which are derived from the three simulators.In the first part of the paper we present a new procedure for incomplete drive cycle data treatment,which is necessary for real drive cycle acquisition in high density cities.Then the models are used to obtain second by second FC and exhaust emissions.Finally,a new methodology named Cycle Analysis by Ordered Power(CAbOP)is presented and used to compare the results.This method consists in the re-ordering of time dependant data,considering the wheel mechanical power domain instead of the standard time domain.This new strategy allows the 5 situations in drive cycles to be clearly visualized:hard breaking zone,slowdowns,idle or stop zone,sustained speed zone and acceleration zone.The complete methodology is applied in two real drive cycles surveyed in Barcelona(Spain)and the results are compared with a standardized WLTC urban cycle.展开更多
This paper presents a hybrid control approach,termed Model Predictive Backstepping Control,for steering angle manipulation.The design of stepping manifolds in the backstepping control incorporates the Lyapunov functio...This paper presents a hybrid control approach,termed Model Predictive Backstepping Control,for steering angle manipulation.The design of stepping manifolds in the backstepping control incorporates the Lyapunov function,posing a challenge in determining optimal stepping parameters for each manifold.In contrast to the predominant focus on constant stepping coefficients in existing research,this study explores the less investigated variable approach.Stepping parameters are introduced as tunable variables and incorporated into a backstepping control law,computed using model predictive control with the backstepping control law using tunable variables as the system input.The hybrid control algorithm utilizes prior knowledge of the control system to identify optimal values for the stepping parameters.The paper comprehensively explores model predictive backstepping control applied to a steer-by-wire system,specifically addressing the resolution of variable stepping parameters through a cost function.The developed algorithm is implemented into a steering control unit and subsequently validated in a real-world steering test vehicle.The results demonstrate successful realization of angle following in the steerby-wire system within an engineering practice context.展开更多
基金The National Natural Science Foundation of China(No.51305078)the Science and Technology Plan of Suzhou City(No.SYG201303)
文摘To improve the semi-empirical model, the slip sinkage effect is analyzed based on the real vehicle test. A dynamic testing system is used to gain the dynamic responses of wheel-soil interactions, The Gauss-Newton algorithm is adopted to estimate the undetermined parameters involved in the slip sinkage models. Wong＇s original model is compared with three typical slip sinkage models on the prediction performance of a drawbar pull. The maximum error rate, root mean squared error and correlation coefficient are utilized to evaluate the performance. The results indicate that the slip sinkage models outperform Wong＇s model and greatly improve the prediction accuracy. Lyasko＇s model is confirmed as an outstanding one for its comprehensive performance. Hence, the existence of the slip sinkage effect is validated. Lyasko＇s model is selected as an optimal one for the practical evaluation of military vehicle trafficability.
基金supported by Jaguar Land Roverthe UK-EPSRC grant EP/N012089/1 as part of the jointly funded Towards Autonomy:Smart and Connected Control(TASCC)Programme
文摘In present-day highly-automated vehicles,there are occasions when the driving system disengages and the human driver is required to take-over.This is of great importance to a vehicle's safety and ride comfort.In the U.S state of California,the Autonomous Vehicle Testing Regulations require every manufacturer testing autonomous vehicles on public roads to submit an annual report summarizing the disengagements of the technology experienced during testing.On 1 January 2016,seven manufacturers submitted their first disengagement reports:Bosch,Delphi,Google,Nissan,Mercedes-Benz,Volkswagen,and Tesla Motors.This work analyses the data from these disengagement reports with the aim of gaining abetter understanding of the situations in which a driver is required to takeover,as this is potentially useful in improving the Society of Automotive Engineers(SAE)Level 2 and Level 3 automation technologies.Disengagement events from testing are classified into different groups based on attributes and the causes of disengagement are investigated and compared in detail.The mechanisms and time taken for take-over transition occurred in disengagements are studied.Finally,recommendations for OEMs,manufacturers,and government organizations are also discussed.
文摘Car fleets escorted by police along Chang’an Avenue are not a rare sight for Beijing residents, who are accustomed to the practice when leaders of foreign states visit the capital of China.
文摘Special axle wheel for motor vehicle inspection is an indispensable special weighing instrument in the process of actual inspection of motor vehicles. This kind of detector belongs to non-automatic weighing instrument, and certain problems will inevitably occur in the actual use process. At present, with the continuous improvement of social economy in our country, the production and ownership of automobiles are in the process of rapid development, and the safety performance of automobiles has also received increasing attention. However, the actual inspection of the axle wheel weight gauge is mainly to check whether the braking force of the motor vehicle can meet the corresponding standard, which plays a very important role in ensuring the safety performance of the whole vehicle. In recent years, relevant motor vehicle safety inspection agencies have used various inspection standards, from the initial GB 21861-2014, GB 7258-2017 safety inspection standard and GB 18565-2016 comprehensive inspection standard to the current revision of GB 3847-2018 and GB 18285-2018 environmental inspection standards. With the continuous revision of comprehensive inspection standards, the demand for talents of relevant motor vehicle safety inspection agencies is getting higher and higher. Only when the comprehensive ability of relevant staff is continuously improved, can they better deal with the inaccurate and unreliable inspection results of motor vehicle safety inspection agencies. Based on this, this paper studies the evaluation of measurement uncertainty of indication value of special axle (wheel) gravimeter for motor vehicle testing, for reference.
文摘The theory of vehicle's correlation tests was discussed and the correlation test mathematical model was created. According to the damage theory, the correlation equation was brought up. The method to solove it was given. The text gives the theory basis of vehicle's correlation tests. The results can be used to give the vehicle's test designation and to make the test to fit the actual environments. Besides that, the methods give acceleration and strengthen effects.
文摘The LM-6 A new generation solid-liquid strap-on launch vehicle has the structural dynamic characteristics of lower frequencies,denser modes and coupling modes in longitudinal,bending and torsion modal space.During the development phase of LM-6 A,modal tests of partial stacks and the full vehicle were designed to obtain the structural dynamic properties.The structural dynamic models using the finite element method(FEM)have been verified and calibrated based on the modal test data.This paper describes the pre-test predictions and test execution,and details the comparison between the pre-test predictions and the test data.The successful maiden flight of LM-6 A further confirmed the effectiveness of structural dynamic modeling and modal test for LM-6 A.
文摘Nowadays harmful gas in vehicle exhaust has pollute d air heavily. To prevent the environment from polluting, the request of emissions control legislation becomes more stringent. New legislation prescribes not only the emissions limitation of vehicles, but also testing instruments and methods. Test car must be operated on the chassis dynamometer and data must be collect ed and analyzed with prescriptive exhaust analysis system as well. The mass of harmful exhaust gas, containing the concentration and volume of emis sion, which is independent from the model of automobile and engine, can be used as a criterion to evaluate the pollution of an automobile. Constant Volume Sampl e System (CVS) is used to measure vehicle emissions, but it is too expensive to apply extensively. The Vehicle Mass Analysis System(Vmas), a new vehicle exhaust mass analysis system produced in USA late 1990s,is used to test and analyze veh icle exhaust. As a test instrument, it has the virtue of cheapness and easy mana geability. In this paper, Vmas is used to measure the emissions of a light truck CA1020F. A ccording to 15 running modes of Vehicle Exhaust Legislation, the test car is ope rated on the chassis dynamometer and data are collected and analyzed with Vmas. The test results show that it is viable to measure and evaluate automobile emiss ion with Vmas. Most of HC exhaust is produced when the car is decelerating. The major factor that influences the mass of HC emission is the sudden decrease of e ngine load causing incomplete combustion in decelerating mode. Test results indi cate CO and NOx are mainly produced in the process of increasing load. The forme r reason is incomplete combustion and the latter is high burning temperature cau sed by the increasing load. The methods of reducing automobile emission are also discussed in this paper.
基金Supported by National Natural Science Foundation of China(Grant Nos.51375212,61601203)Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions of China+1 种基金Key Research and Development Program of Jiangsu Province(BE2016149)Jiangsu Provincial Natural Science Foundation of China(BK20140555)
文摘The accurate control for the vehicle height and leveling adjustment system of an electronic air suspension(EAS) still is a challenging problem that has not been effectively solved in prior researches. This paper proposes a new adaptive controller to control the vehicle height and to adjust the roll and pitch angles of the vehicle body(leveling control) during the vehicle height adjustment procedures by an EAS system. A nonlinear mechanism model of the full?car vehicle height adjustment system is established to reflect the system dynamic behaviors and to derive the system optimal control law. To deal with the nonlinear characters in the vehicle height and leveling adjustment processes, the nonlinear system model is globally linearized through the state feedback method. On this basis, a fuzzy sliding mode controller(FSMC) is designed to improve the control accuracy of the vehicle height adjustment and to reduce the peak values of the roll and pitch angles of the vehicle body. To verify the effectiveness of the proposed control method more accurately, the full?car EAS system model programmed using AMESim is also given. Then, the co?simulation study of the FSMC performance can be conducted. Finally, actual vehicle tests are performed with a city bus, and the test results illustrate that the vehicle height adjustment performance is effectively guaranteed by the FSMC, and the peak values of the roll and pitch angles of the vehicle body during the vehicle height adjustment procedures are also reduced significantly. This research proposes an effective control methodology for the vehicle height and leveling adjustment system of an EAS, which provides a favorable control performance for the system.
文摘The deployment of autonomous vehicles is rapidly evolving,bringing both unprecedented opportunities and challenges.To achieve safer autonomous driving,the role of testing has become paramount,serving as the cornerstone for validating the performance,robustness,and trustworthiness of autonomous driving systems.Unlike traditional vehicle testing,the focus of autonomous vehicle testing is on their intended driving functionality in complex driving environments.The burgeoning field of autonomous vehicle testing requires not only an understanding of current technological landscapes but also a proactive exploration of innovative solutions to advance the field,particularly through the application of artificial intelligence and simulation-based approaches.Within the spectrum of autonomous vehicle testing,the evolving challenges demand advancements in key technologies,including the construction and generalization of testing scenarios,the recognition of risky scenarios,driving behavior modeling,comprehensive testing evaluation,evidence-based testing protocols,simulation toolchain development,and more.
基金Project(51105017) supported by the National Natural Science Foundation of ChinaProject(2011BAG09B00) supported by the National Science and Technology Support Program of ChinaProject(2010DFB80020) supported by the Technology Major Project of the Ministry of Science and Technology of China
文摘For the purpose of engineering development for a new 8-step speed automatic transmission,a simplified dynamic model for this gearbox was established and key parameters which affected the shift quality were analyzed.Aiming at four different shift types,the ideal characteristics of shift clutch and engine control were set up.By using torque estimation method,PI slip control algorithm and engine coordinated control principle,the control model and transmission controller were well developed for three shift phases which included rapid-fill phase,torque phase and inertia phase.The testing environment on the rig and prototype vehicle level was built and the testing results obtained in ultimate condition could verify the accuracy and feasibility of this shift control strategy.The peak jerk during shift process was controlled within ±2 g/s where the smooth gearshift was obtained.The development proposal and algorithm have a high value for engineering application.
基金Supported by the National High Technology Research and Development Program of China(863 Program)(2012AA112101)
文摘With an advanced foreign hydraulic automatic transmission as the objective,an analytical method for the gear-shifting schedule is proposed.First the demanded maximum gradient of test is estimated.Then a test scheme and analytical procedure is formulated by initial test and hypothetical shift parameters.Finally through gear-shifting tests under different road conditions,load,accelerator pedal position limitation,throttle opening and output shaft speed are found to be the gear-shifting parameters.Under a common road condition,the gear-shifting schedule is a double-parameter schedule.Based on the driver＇s demands on braking and dynamic performance,different shift schedules are made under downhill,uphill and quick releasing acceleration pedal conditions.The operation criteria of down-shift schedule on abrupt grade are proposed.
基金the financial support of the Natural Sciences and Engineering Research Council of Canada(NSERC)。
文摘Adverse weather conditions increase road risks;thus,weather testing is necessary to evaluate vehicle performance.Outdoor testing is the most realistic,but it is not as controlled,repeatable,and rapid as indoor testing using an artificial precipitation system.However,outdoor data is still desirable for establishing the simulation targets on the vehicle surfaces.The dynamic-to-static precipitation intensity ratio is a useful parameter to correlate natural precipitation with perceived precipitation experienced by the moving vehicle.Theoretically,the amount of precipitation experienced by a translating surface depends on the orientation and travel speed.However,there are other external factors that could affect the perceived intensity,such as wind,turbulence,and droplet size distribution(DSD).Therefore,the existing simplified models evaluating a number of droplet strikes or precipitation flux calculated using natural precipitation density fail to have accurate predictions of the perceived precipitation rate,which hinders the evaluation vehicle application performance,such as sensor perception.In the present work,a semi-empirical prediction model is developed from the physics of precipitation in the context of vehicle aerodynamics and atmospheric dynamics.This model is validated with outdoor testing on a track for three days with rainy conditions.Multiple optical disdrometers are used to evaluate the precipitation rate experienced by a moving vehicle at different surface orientations through meteorological observations obtained in real-time from a nearby stationary meteorological tower and a moving vehicle.The data acquisition and processing methods are presented in detail.Results suggested that the proposed model is found to improve the current simplified mathematical expressions and is repeatable.It is found that improvements in prediction accuracy of perceived precipitation intensity compared to existing methods are usually more than 50%.
基金financial support of the National Science Foundation of China Project:52072215National Natural Science Foundation of China grant 52221005+2 种基金Beijing Natural Science Foundation(L243025)National key R&D Program of China:2022YFB2503003State Key Laboratory of Intelligent Green Vehicle and Mobility.
文摘Safety testing is a crucial phase in the development of autonomous vehicles,with scenarios serving as the fundamental medium for these tests.The construction of scenarios that accurately reflect the real-world traffic behavior is a key challenge for autonomous vehicle testing technology,given the need for authenticity and effectiveness in testing.Addressing this,this study introduces a method for generating test scenarios specifically for intersections.This method involves decoupling the scenario into interactive and non-interactive layers.For the interactive elements,namely the traffic participants,this study proposes a novel approach to construct a human-like decision-making model adapted to intersections,with the OF-T-GAIL algorithm at its core.This algorithm,through a novel perception-decision representation and an omnidirectional coordinate system transformation,effectively reduces the cumulative error in the trajectory generation.Furthermore,this model is extended to multiple agents,allowing the bulk generation of intersection test scenario segments.These scenarios and the traffic participant(TP)models are validated using the SinD dataset,demonstrating the applicability and effectiveness of the approach in creating testing environments for autonomous driving systems.
文摘An efficient method for helicopter rotor fault diagnosis was proposed using diagnostic matrix and its software framework was developed.The diagnostic matrix was extracted by the way of simulating the quantitative models of damaged and undamaged rotor systems.The conflicts were recognized by the virtual symptom sensor based on the dependencies between symptoms and faults.Diagnostic candidates were generated by the Boolean hitting algorithm.The proposed method provides multi-fault real-time diagnostic capability and it is suitable for the synthetic health monitoring of complex systems.
基金the 111 Project(Grant No.B17034)National Natural Science Foundation of the People’s Republic of China(Grant No.51505354).
文摘An accurate estimation of a vehicle’s state of motion is the basis of dynamic stability control.Two different nonlinear Kalman filters are adopted for the estimation of the vehicle’s lateral/rollover stability state.First,the overall structure of the state estimation with four inputs and four outputs is introduced.After determining tire-cornering stiffness using a recursive leastsquares(RLS)method,the equations of state and of observation for the nonlinear Kalman filter are established based on a vehicle model with four degrees of freedom including planar and rollover dynamics.Then,the specific steps of real-time state estimation using the extended Kalman filter(EKF)and unscented Kalman filter(UKF)are both given.In a co-simulation,we find that the RLS algorithm estimates tire-cornering stiffness accurately and quickly,and the UKF improves the effect of state estimation compared with EKF.In addition,the UKF is verified against data from vehicle tests.The results show the proposed method is reliable and practical in estimating vehicle states.
基金supported by the National Key R&D Program of China(2021YFB2501200)the National Natural Science Foundation of China(52131204)the Shaanxi Province Key Research and Development Program(2022GY-300).
文摘With the increasing level of automation of autonomous vehicles,it is important to conduct comprehensive and extensive testing before releasing autonomous vehicles into the market.Traditional public road and closed-field testing failed to meet the requirements of high testing efficiency and scenario coverage.Therefore,scenario-based autonomous vehicle simulation testing has emerged.Many scenarios form the basis of simulation testing.Generating additional scenarios from an existing scenario library is a significant problem.Taking the scenarios of a proceeding vehicle cutting into an adjacent lane on highways as an example,based on an autoencoder and a generative adversarial network(GAN),a method that combines Transformer to capture the features of a long-time series,called SceGAN,is proposed to model and generate scenarios of autonomous vehicles on highways.An evaluation system is established to analyze the reliability of SceGAN using discriminative and predictive scores and further evaluate the effect of scenario generation in terms of similarity and coverage.Experiments showed that compared with TimeGAN and AEGAN,SceGAN is superior in data fidelity and availability,and their similarity increased by 27.22%and 21.39%,respectively.The coverage increased from 79.84%to 93.98%as generated scenarios increased from 2,547 to 50,000,indicating that the proposed method has a strong generalization capability for generating multiple trajectories,providing a basis for generating test scenarios and promoting autonomous vehicle testing.
基金supported in part by the National Key R&D Program of China(2021YFB2501201)in part by the National Natural Science Foundation of China(52402491,52202488)+1 种基金in part by the Fundamental Research Funds for the Central Universities,CHD(300102224207,300102244201)in part by the Science and Technology Department of Shaanxi Province(2024GXYBXM-260,2024CG-CGZH-19,2022GY-309,2022JQ-543).
文摘Unlike widely used ADAS test approaches based on predefined typical scenarios,a new ADAS test methodology has been proposed by the United Nations Economic Commission for Europe Regulation No.157(ECE R 157),which verifies whether ADAS meet safety requirements by comparing them to driver performance models.However,whether the driver performance models in ECE R157 can be utilized to characterize driver behaviors in China has not been validated,which limits advancements of globally consistent ADAS test procedures.In order to compare human drivers with the cut-in performance model in ECE R157,51 cut-in cases from 65,000 km naturalistic driving data collected in China were applied to analyze response characteristics of following vehicle’s drivers in the cut-in scenario.The results can be summarized as follows.First of all,90%of the drivers release accelerators and 75%of the drivers brake before lane-changers reach lane lines,whereas the cut-in performance model in ECE R157 brakes about 0.95 s after lane-changers reach lane lines.This phenomenon can be explained by preview features of drivers.Secondly,some drivers release accelerators until they see clear lane-changing maneuvers,whereas some drivers anticipate possibilities of lane-changing very early and release accelerators in advance.Thirdly,time headway should be employed as a risk estimator in the cut-in scenario rather than time-to-collision.These results can help to calibrate parameters in the cut-in performance model of ECE R157 according to behaviors of Chinese drivers and increase the scope of application for the test methodology proposed in ECE R157.
文摘In this work three fuel consumption and exhaust emission models,ADVISOR,VT-MICRO and the European Environmental Agency Emission factors,have been used to obtain fuel consumption(FC)and exhaust emissions.These models have been used at micro-scale,using the two signal treatment methods presented.The manuscript presents:1)a methodology to collect data in real urban driving cycles,2)an estimation of FC and tailpipe emissions using some available models in literature,and 3)a novel analysis of the results based on delivered wheel power.The results include Fuel Consumption(FC),CO_(2),NO_(x) and PM_(10) emissions,which are derived from the three simulators.In the first part of the paper we present a new procedure for incomplete drive cycle data treatment,which is necessary for real drive cycle acquisition in high density cities.Then the models are used to obtain second by second FC and exhaust emissions.Finally,a new methodology named Cycle Analysis by Ordered Power(CAbOP)is presented and used to compare the results.This method consists in the re-ordering of time dependant data,considering the wheel mechanical power domain instead of the standard time domain.This new strategy allows the 5 situations in drive cycles to be clearly visualized:hard breaking zone,slowdowns,idle or stop zone,sustained speed zone and acceleration zone.The complete methodology is applied in two real drive cycles surveyed in Barcelona(Spain)and the results are compared with a standardized WLTC urban cycle.
基金supported by Key Research and Development Program of Jiangsu Province under granted BE2021006-2Natural Science Foundation of Anhui Province under granted 2308085ME163Foundation of State Key Laboratory of Automotive Simulation and Control.
文摘This paper presents a hybrid control approach,termed Model Predictive Backstepping Control,for steering angle manipulation.The design of stepping manifolds in the backstepping control incorporates the Lyapunov function,posing a challenge in determining optimal stepping parameters for each manifold.In contrast to the predominant focus on constant stepping coefficients in existing research,this study explores the less investigated variable approach.Stepping parameters are introduced as tunable variables and incorporated into a backstepping control law,computed using model predictive control with the backstepping control law using tunable variables as the system input.The hybrid control algorithm utilizes prior knowledge of the control system to identify optimal values for the stepping parameters.The paper comprehensively explores model predictive backstepping control applied to a steer-by-wire system,specifically addressing the resolution of variable stepping parameters through a cost function.The developed algorithm is implemented into a steering control unit and subsequently validated in a real-world steering test vehicle.The results demonstrate successful realization of angle following in the steerby-wire system within an engineering practice context.
