A kind of construction truck model is built in Adams based on multi-body dynamic theory. The rigid and elastic wheels of tire-soil contact models are proposed based on the Bekker pressure model and the Jonasi shear so...A kind of construction truck model is built in Adams based on multi-body dynamic theory. The rigid and elastic wheels of tire-soil contact models are proposed based on the Bekker pressure model and the Jonasi shear soil model, and they are described in the form of S-function to enhance the calculation efficiency and simulation accuracy. Finally, the interaction of truck and soil is simulated by Adams-Maflab co-simulation to study the influence of soft terrain on the ride comfort of vehicles. The co-simulation results reveal that the terrain properties have a great influence on the ride comfort of vehicles as well as driving speed, road roughness and cargo weight. This co-simulation model is convenient for adding the factor of terrain deformation to the analysis of vehicle ride comfort. It can also be used to optimize suspension system parameters especially for off-road vehicles.展开更多
Mathematical models of tire-lateral mad adhesion for use in mad vehicle dynamics studies are set up to express the relations of adhesion coefficients with slip ratio in lateral direction.The models of tire-lateral mad...Mathematical models of tire-lateral mad adhesion for use in mad vehicle dynamics studies are set up to express the relations of adhesion coefficients with slip ratio in lateral direction.The models of tire-lateral mad adhesion revolutionize the Pacejka's model in concept and therefore make it possible for applications in vehicle dynamics studies by the expression of lateral adhesion coefficient as a function of wheel slip ratio,instead of the wheel slip angle,taking into account in the mean time the influences of mad surface condition, vehicle velocity,vertical load,tire slip angle,and wheel camber angle.展开更多
Rolling resistance of tires is one of the most important factors influencing energy consumption of road vehicles, especially on rural roads. For practical reasons, most of rolling resistance measurements are usually p...Rolling resistance of tires is one of the most important factors influencing energy consumption of road vehicles, especially on rural roads. For practical reasons, most of rolling resistance measurements are usually performed for dry road conditions. Based on the fact that roads are wet during a considerable time over the year and as part of the projects MIR/AM, ROLRES and ROSANNE, the TUG （Technical University of Gdafisk） in Poland and VTI （Swedish National Road and Transport Research Institute） in Sweden carried out trailer rolling resistance measurements on wet road surfaces to investigate water film influence on rolling resistance on different pavements. A specially-designed trailer to measure rolling resistance has been used. The test sections were both rural roads and an abandoned airfield equipped with water film sensors mounted in the pavement. Results indicate strong influence of test speed and water film depth, as well as influence of surface texture. The increase of rolling resistance on wet surfaces is caused by both hydrodynamic phenomena and cooling effect of water that decreases tire temperature thus increasing rolling resistance.展开更多
To resolve the path tracking problem of autonomous ground vehicles,an analysis of existing path tracking methods was carried out and an important conclusion was got.The vehicle-road model is crucial for path following...To resolve the path tracking problem of autonomous ground vehicles,an analysis of existing path tracking methods was carried out and an important conclusion was got.The vehicle-road model is crucial for path following.Based on the conclusion,a new vehicle-road model named "ribbon model" was constructed with consideration of road width and vehicle geometry structure.A new vehicle-road evaluation algorithm was proposed based on this model,and a new path tracking controller including a steering controller and a speed controller was designed.The difficulties of preview distance selection and parameters tuning with speed in the pure following controller are avoided in this controller.To verify the performance of the novel method,simulation and real vehicle experiments were carried out.Experimental results show that the path tracking controller can keep the vehicle in the road running as fast as possible,so it can adjust the control strategy,such as safety,amenity,and rapidity criteria autonomously according to the road situation.This is important for the controller to adapt to different kinds of environments,and can improve the performance of autonomous ground vehicles significantly.展开更多
This paper presents a description and analysis of the most important models to predict each of the Road User Costs components （Vehicle Operating Costs, Accident Costs and Value of Time） and proposes a model for esti...This paper presents a description and analysis of the most important models to predict each of the Road User Costs components （Vehicle Operating Costs, Accident Costs and Value of Time） and proposes a model for estimating RUC components suitable for the Portuguese road network. These results are part of a research which aimed to obtain a Road User Cost Model to be used as a tool in road management systems. This model is different from other models by the fact that it includes a simple formulation that allows calibration and calculation of cost parameters, for any year, in a simple and fast way, providing trustworthy results. The required data is already available in Portuguese institutions, allowing periodic revision of cost parameters to insure accuracy.展开更多
This paper intends to develop finite element models that can simulate vehicle load moving on pavement system and reflect the pavement response of vehicle and pavement interaction.We conduct parametric analysis conside...This paper intends to develop finite element models that can simulate vehicle load moving on pavement system and reflect the pavement response of vehicle and pavement interaction.We conduct parametric analysis considering the influences of asphalt concrete layer modulus and thickness,base layer modulus and thickness,and subgrade modulus on pavement surface displacement,frequency,and strain response.The analysis findings are fruitful.Both the displacement basin width and maximum value of dynamic surface displacements are larger than those of static surface displacements.The frequency is positively correlated with the pavement structure moduli,and negatively correlated with the pavement structure thicknesses.The shape of dynamic and static tensile strain is similar along the depth of the pavement structure.The maximum value of dynamic tensile strain is larger than that of static tensile strain.The frequency of entire pavement structure holds more significant influence than the surface displacement and strain do.The subgrade modulus has a significant effect on surface displacement,frequency and strain.展开更多
Vibration-based pavement condition(roughness and obvious anomalies)monitoring has been expanding in road engineering.However,the indistinctive transverse cracking has hardly been considered.Therefore,a vehicle-based n...Vibration-based pavement condition(roughness and obvious anomalies)monitoring has been expanding in road engineering.However,the indistinctive transverse cracking has hardly been considered.Therefore,a vehicle-based novel method is proposed for detecting the transverse cracking through signal processing techniques and support vector machine(SVM).The vibration signals of the car traveling on the transverse-cracked and the crack-free sections were subjected to signal processing in time domain,frequency domain and wavelet domain,aiming to find indices that can discriminate vibration signal between the cracked and uncracked section.These indices were used to form 8 SVM models.The model with the highest accuracy and F1-measure was preferred,consisting of features including vehicle speed,range,relative standard deviation,maximum Fourier coefficient,and wavelet coefficient.Therefore,a crack and crack-free classifier was developed.Then its feasibility was investigated by 2292 pavement sections.The detection accuracy and F1-measure are 97.25%and 85.25%,respectively.The cracking detection approach proposed in this paper and the smartphone-based detection method for IRI and other distress may form a comprehensive pavement condition survey system.展开更多
Based on economics theory,social value loss caused by vehicle involved in crashes as well as various factors influencing on it were analyzed,the corresponding mi- cro-econometrics model was theoretically given.Moreove...Based on economics theory,social value loss caused by vehicle involved in crashes as well as various factors influencing on it were analyzed,the corresponding mi- cro-econometrics model was theoretically given.Moreover,the practicability of the model, the veracity and rationality of quantification were analyzed.Based on probability theory and mathematical statistical theory,macro approach to evaluating vehicle damage in crashes was presented,and the corresponding macro-econometrics model was con- structed.In addition,the macro-econometrics model was utilized to assess economic loss from statistical data of vehicle damaged in crashes,which has shown that the model can meet the demand of quantification analysis of vehicle damage,and be applied to the evaluation of economic loss caused by crashes.The results in this paper will be of practic- al significance for scientific,comprehensive and rational evaluating socio-economic loss caused by road crashes.展开更多
In order to improve the transmission accuracy and efficiency of sensing and actuating signals in Internet of Things （loT） and ensure the system stability, an adaptive resource allocation algorithm is proposed, which...In order to improve the transmission accuracy and efficiency of sensing and actuating signals in Internet of Things （loT） and ensure the system stability, an adaptive resource allocation algorithm is proposed, which dynami- cally assigns the network bandwidth and priority among components according to their signals＇ frequency domain characteristics. A remote sensed and controlled unmanned ground vehicle （UGV） path tracking test-bed was devel- oped and multiple UGV＇s tracking error signals were measured in the simulation for performance evaluation. Results show that with the same network bandwidth constraints, the proposed algorithm can reduce,, the accumulated and maximum errors of UGV path tracking by over 60% compared with the conventional static algorithm.展开更多
基金The National Natural Science Foundation of China(No.50575040)the Natural Science Foundation of Jiangsu Province(No.BK2007112)
文摘A kind of construction truck model is built in Adams based on multi-body dynamic theory. The rigid and elastic wheels of tire-soil contact models are proposed based on the Bekker pressure model and the Jonasi shear soil model, and they are described in the form of S-function to enhance the calculation efficiency and simulation accuracy. Finally, the interaction of truck and soil is simulated by Adams-Maflab co-simulation to study the influence of soft terrain on the ride comfort of vehicles. The co-simulation results reveal that the terrain properties have a great influence on the ride comfort of vehicles as well as driving speed, road roughness and cargo weight. This co-simulation model is convenient for adding the factor of terrain deformation to the analysis of vehicle ride comfort. It can also be used to optimize suspension system parameters especially for off-road vehicles.
文摘Mathematical models of tire-lateral mad adhesion for use in mad vehicle dynamics studies are set up to express the relations of adhesion coefficients with slip ratio in lateral direction.The models of tire-lateral mad adhesion revolutionize the Pacejka's model in concept and therefore make it possible for applications in vehicle dynamics studies by the expression of lateral adhesion coefficient as a function of wheel slip ratio,instead of the wheel slip angle,taking into account in the mean time the influences of mad surface condition, vehicle velocity,vertical load,tire slip angle,and wheel camber angle.
文摘Rolling resistance of tires is one of the most important factors influencing energy consumption of road vehicles, especially on rural roads. For practical reasons, most of rolling resistance measurements are usually performed for dry road conditions. Based on the fact that roads are wet during a considerable time over the year and as part of the projects MIR/AM, ROLRES and ROSANNE, the TUG （Technical University of Gdafisk） in Poland and VTI （Swedish National Road and Transport Research Institute） in Sweden carried out trailer rolling resistance measurements on wet road surfaces to investigate water film influence on rolling resistance on different pavements. A specially-designed trailer to measure rolling resistance has been used. The test sections were both rural roads and an abandoned airfield equipped with water film sensors mounted in the pavement. Results indicate strong influence of test speed and water film depth, as well as influence of surface texture. The increase of rolling resistance on wet surfaces is caused by both hydrodynamic phenomena and cooling effect of water that decreases tire temperature thus increasing rolling resistance.
基金Project(90820302)supported by the National Natural Science Foundation of China
文摘To resolve the path tracking problem of autonomous ground vehicles,an analysis of existing path tracking methods was carried out and an important conclusion was got.The vehicle-road model is crucial for path following.Based on the conclusion,a new vehicle-road model named "ribbon model" was constructed with consideration of road width and vehicle geometry structure.A new vehicle-road evaluation algorithm was proposed based on this model,and a new path tracking controller including a steering controller and a speed controller was designed.The difficulties of preview distance selection and parameters tuning with speed in the pure following controller are avoided in this controller.To verify the performance of the novel method,simulation and real vehicle experiments were carried out.Experimental results show that the path tracking controller can keep the vehicle in the road running as fast as possible,so it can adjust the control strategy,such as safety,amenity,and rapidity criteria autonomously according to the road situation.This is important for the controller to adapt to different kinds of environments,and can improve the performance of autonomous ground vehicles significantly.
文摘This paper presents a description and analysis of the most important models to predict each of the Road User Costs components （Vehicle Operating Costs, Accident Costs and Value of Time） and proposes a model for estimating RUC components suitable for the Portuguese road network. These results are part of a research which aimed to obtain a Road User Cost Model to be used as a tool in road management systems. This model is different from other models by the fact that it includes a simple formulation that allows calibration and calculation of cost parameters, for any year, in a simple and fast way, providing trustworthy results. The required data is already available in Portuguese institutions, allowing periodic revision of cost parameters to insure accuracy.
基金supported by the National Natural Science Foundation of China(No.51178456)。
文摘This paper intends to develop finite element models that can simulate vehicle load moving on pavement system and reflect the pavement response of vehicle and pavement interaction.We conduct parametric analysis considering the influences of asphalt concrete layer modulus and thickness,base layer modulus and thickness,and subgrade modulus on pavement surface displacement,frequency,and strain response.The analysis findings are fruitful.Both the displacement basin width and maximum value of dynamic surface displacements are larger than those of static surface displacements.The frequency is positively correlated with the pavement structure moduli,and negatively correlated with the pavement structure thicknesses.The shape of dynamic and static tensile strain is similar along the depth of the pavement structure.The maximum value of dynamic tensile strain is larger than that of static tensile strain.The frequency of entire pavement structure holds more significant influence than the surface displacement and strain do.The subgrade modulus has a significant effect on surface displacement,frequency and strain.
基金Project(51778482)supported by the National Natural Science Foundation of China。
文摘Vibration-based pavement condition(roughness and obvious anomalies)monitoring has been expanding in road engineering.However,the indistinctive transverse cracking has hardly been considered.Therefore,a vehicle-based novel method is proposed for detecting the transverse cracking through signal processing techniques and support vector machine(SVM).The vibration signals of the car traveling on the transverse-cracked and the crack-free sections were subjected to signal processing in time domain,frequency domain and wavelet domain,aiming to find indices that can discriminate vibration signal between the cracked and uncracked section.These indices were used to form 8 SVM models.The model with the highest accuracy and F1-measure was preferred,consisting of features including vehicle speed,range,relative standard deviation,maximum Fourier coefficient,and wavelet coefficient.Therefore,a crack and crack-free classifier was developed.Then its feasibility was investigated by 2292 pavement sections.The detection accuracy and F1-measure are 97.25%and 85.25%,respectively.The cracking detection approach proposed in this paper and the smartphone-based detection method for IRI and other distress may form a comprehensive pavement condition survey system.
基金Communications Bureau of Shandong Province(2005R17)
文摘Based on economics theory,social value loss caused by vehicle involved in crashes as well as various factors influencing on it were analyzed,the corresponding mi- cro-econometrics model was theoretically given.Moreover,the practicability of the model, the veracity and rationality of quantification were analyzed.Based on probability theory and mathematical statistical theory,macro approach to evaluating vehicle damage in crashes was presented,and the corresponding macro-econometrics model was con- structed.In addition,the macro-econometrics model was utilized to assess economic loss from statistical data of vehicle damaged in crashes,which has shown that the model can meet the demand of quantification analysis of vehicle damage,and be applied to the evaluation of economic loss caused by crashes.The results in this paper will be of practic- al significance for scientific,comprehensive and rational evaluating socio-economic loss caused by road crashes.
基金Supported by Natural Science Foundation of Tianjin (No. 07JCZDJC05800)Science and Technology Supporting Plan of Tianjin (No. 09ZCKFGX29200)
文摘In order to improve the transmission accuracy and efficiency of sensing and actuating signals in Internet of Things （loT） and ensure the system stability, an adaptive resource allocation algorithm is proposed, which dynami- cally assigns the network bandwidth and priority among components according to their signals＇ frequency domain characteristics. A remote sensed and controlled unmanned ground vehicle （UGV） path tracking test-bed was devel- oped and multiple UGV＇s tracking error signals were measured in the simulation for performance evaluation. Results show that with the same network bandwidth constraints, the proposed algorithm can reduce,, the accumulated and maximum errors of UGV path tracking by over 60% compared with the conventional static algorithm.
