Road Friendliness Research Articles

Human-bus-road coupled vibration considering effect of braking forces

The ride comfort of vehicles traveling on the road has always been a concern. In addition, the braking force of vehicles will aggravate the damage to road structures and reduce the comfort of drivers and passengers. In the present study, the dynamic response of pavement, road friendliness, and human comfort are investigated by setting up the human-bus-road coupled vibration system considering the braking forces. Firstly, the three-dimensional finite element model of asphalt pavement with interlayer contact and the human-bus model with multiple degrees of freedom (2n + 7) were established to analyze the dynamic responses of asphalt pavement, human body, and bus under different braking conditions. Then, the dynamic load coefficients of wheels under different combined conditions were investigated to evaluate the road friendliness and the human annoyance rate was adopted to evaluate the human comfort. The results show that for the asphalt pavement, the shear stress of the pavement is larger than the normal stress due to the bus braking, and the combined effect of road surface roughness and braking force on the road friendliness is the largest. For the human comfort, the pitch acceleration of human body increases more than the roll acceleration due to bus braking, resulting in the decreased human comfort and increased annoyance rate.

Assessing the Efficiency of the Air Isolation System Based on the Mathematical Models

Two calculation methods of the lumped parameter model (LPM) and mass flow ratio (MFR) used to establish dynamics models of air isolation system (AIS) in vehicles are widely applied. However, the efficiency and application range of the LPM and MFR for the AIS of the vehicles have not been explained in detail. To clarify this issue, the numerical simulation and experiment of the AIS performed under the harmonic excitation are given to evaluate the accuracy of the LPM and MFR. The two-axle automobiles and multi-axle heavy trucks equipped with the AIS are also simulated to evaluate the efficiency of the AIS with the LPM and MFR in improving ride comfort and road friendliness. The study shows that with the single model of the AIS, measured and simulated result in AIS's force response, force-deformation characteristic, and dynamics stiffness-frequency characteristic with LPM and MFR are similar. Therefore, both methods could be applied to establish the dynamic model of the AIS. However, by applying the AIS on the two-axle and multi-axle vehicles, the MFR improves road-friendliness and comfort in two-axle automobiles better than the LPM, conversely, the LPM improves road-friendliness and comfort in multi-axle trucks better than that the MFR. Therefore, to more accurately assess the isolation efficiency of the AIS in improving road-friendliness and comfort in vehicle, the MFR should be applied to the AIS using the pipe designed by the parallel pipes or long pipes of two-axle vehicles whereas the LPM should be applied to the AIS using the pipe designed by the complex pipes of multi-axle vehicles.

Improving ride comfort and road friendliness of heavy truck using semi-active suspension system

To enhance the ride comfort and improve the road friendliness of the heavy truck, based on the dynamic model of the heavy truck, the semi-active suspension system of the vehicle is proposed and controlled based on the fuzzy logic control and Matlab/Simulink software. The efficiency of the semi-active suspension system is then evaluated based on the indexes of the root mean square acceleration of the driver’s seat, the root mean square acceleration of the cab's pitching angle, and the dynamic load coefficient of the wheel axles. The results show that with the semi-active suspension system of the heavy truck controlled by the fuzzy logic control, the acceleration responses of the heavy truck and the dynamic forces of the wheel axles are greatly reduced in comparison with the passive suspension system under various operating conditions of the loads and speeds. Especially, with the semi-active suspension system controlled by the fuzzy logic control, the root mean square accelerations of the driver’s seat and cab pitch angle; and the dynamic load coefficient at 2nd axle of the wheel are clearly reduced by 23.7 %, 27.2 %, and 20.9 % in comparison with the passive suspension system, respectively. Thus, both ride comfort and road friendliness of the heavy truck are improved by the semi-active suspension system. In addition, the vehicle load insignificantly affects ride comfort. However, it greatly affects the road damage, especially with the half load condition of the vehicle. Thus, to improve road friendliness, the full load condition of the vehicle should be used.

Study on Vehicle Vibration Response under the Condition of 3D Tire–Pavement Contact for Unmanned Driving

Unmanned driving is the direction of future development in the field of transportation. The development of unmanned driving will cause sensor monitoring and machine control to play a greater role. According to road roughness data collected by unmanned ground vehicles and vehicle dynamics, it is of great significance to establish a vehicle–pavement coupling model to analyze and guide driving comfort, cargo safety, and road friendliness. Pavement roughness is the main external excitation in the process of driving a vehicle. Therefore, a three-dimensional (3D) model of pavement roughness was constructed based on fractal theory and fractal interpolation. According to tire–pavement contact characteristics, a newly rerevised 3D flexible roller contact tire model was proposed. On this basis, vehicle vibration dynamics models for a car and a truck were established. The traditional point contact model was used to verify the model. Based on the comfort threshold of a passenger, the cargo vibration threshold, and the dynamic load coefficient (DLC) threshold of the truck, the conditions for ride comfort of an unmanned ground vehicle were expounded. The results showed that, compared with an ideal fully flat road surface, pavement roughness had a great impact on vehicle vibration. The 3D model of pavement roughness generated had high accuracy. The vehicle–pavement coupling model based on tire–pavement 3D contact under 3D pavement roughness excitation was correct. The proposed model can calculate vibration characteristics of passengers and cargo and the DLC of wheels in real time. For different types of vehicles and different roughness levels of pavement, different speed thresholds were given to ensure driving comfort, cargo safety, and road friendliness. Driving speed and each evaluation index met the Fourier function relationship. Partial correlation analysis showed that in order to ensure the comfort of passengers, more attention should be paid to pavement roughness, and for cargo safety and road friendliness, pavement roughness and vehicle speed should be considered at the same time. The results provide theoretical suggestions for the comfortable driving of future unmanned ground vehicles.

Sensitivity analysis and multi-objective optimization of the virtual track train parameters considering the coupling effect between vehicles

To improve vehicle stability, passenger comfort and road friendliness of the virtual track train (VTT) negotiating curves, a multi-parameter and multi-objective optimization platform combining the VTT dynamics model, Sobal sensitivity analysis, NSGA-II algorithm and [Formula: see text] optimal selection method is developed. Considering the mutual coupling between vehicles and taking random road roughness as excitation, the VTT dynamics model with 66-DOF is constructed and verified. Design variables and objective functions are defined, and then key design variables are obtained via Sobol sensitivity analysis. The NSGA-II algorithm is used to optimize the key design variables of the VTT, and the [Formula: see text] optimal selection method is used to select the Pareto solution sets. The results demonstrate that the optimization platform can effectively reduce the number of design variables (from 11 to 6) and improve stability, lateral comfort, vertical comfort and road friendliness, (2.78%, 1.19% and 14.71%, 3.09%, respectively). Also, a multi-parameter and multi-objective optimization platform of the VTT has certain applicability to straight-line conditions and different curve radius conditions. This research provides a feasible solution for the comprehensive performance improvement of the VTT passing through a minor curve. In addition, it also provides a reference for the optimization analysis of multi-marshaling vehicles considering the interaction between vehicles.

Analysis of ride comfort and road friendliness of heavy vehicle inertial suspension based on the ground-hook control strategy

In order to comprehensively improve the ride comfort performance and the road friendliness performance of the heavy vehicles, an inertial suspension using ground-hook (GH) control is proposed in this paper, and the suspension performances are compared at different loading rates and driving speeds. Firstly, a half vehicle model of the inertial suspension of the heavy vehicle based on the GH control is established. Then, the key parameters of the GH inertial suspension are optimized by the genetic algorithm and the system simulations are carried out. By comparing to the conventional passive suspension, the root-mean-square (RMS) of the vertical acceleration of the body centroid is reduced by 4.87%, and the RMS of the dynamic tire loads of the front and the rear wheels are reduced by 16.19% and 10.02%, respectively. Results show that the GH inertial suspension can effectively coordinate and improve the ride comfort and road friendliness of heavy vehicles simultaneously.

Research on predictive coordinated control of ride comfort and road friendliness for heavy vehicle ISD suspension based on the hybrid-hook damping strategy

With the appearance of inerter, the ISD suspension composed of “Inerter-Spring-Damper” opens up a new direction for efficient coordination of ride comfort and road friendliness for heavy vehicles. In this paper, a reference model based on the hybrid-hook damping strategy is proposed, and the mechatronic inerter is used as an active suspension force generator in the actual controlled model. Then, the coordinated control of the vehicle ISD suspension model is realized by the model predictive control (MPC) approach. The test results show that, the RMS values of the body acceleration and dynamic tire load of the controllable ISD suspension is smaller than the traditional passive and passive ISD suspension under the sinusoidal road inputs. Under the random road input, compared with the traditional passive suspension, the controllable ISD suspension has improved the RMS value of the body acceleration by 26.61%, and the road damage coefficient has been improved by 20.13%. Experiments show that the controllable ISD suspension of heavy vehicles based on the hybrid-hook damping strategy has comprehensive improvement of vehicle ride comfort and road friendliness.

Modeling of hydro-pneumatic suspension system with fractional order terms and simulation analysis of road friendliness

To establish the hydro-pneumatic suspension model more accurately and better analyze the influence of heavy vehicle hydro-pneumatic suspension system on road friendliness, the fractional order theory is applied to modeling, and the mathematical model and dynamics model of dual-chamber hydro-pneumatic suspension with fractional order are established by using Matlab/Simulink, and the fractional order differential term of the suspension system is calculated according to the improved Oustaloup filter. The effect of fractional order on suspension stiffness, damping and output forces is also investigated. The optimal fractional order is determined to be 0.9 for the design of a combined suspension performance index function. The vibration law of increasing amplitude and error of fractional-order is obtained through simulation, and the model with fractional-order is described more accurately. A sliding film variable structure controller was established for control. The simulation results were analyzed by means of theoretical road damage factors and dynamic load factors. The results show that the suspension system model with fractional order terms can effectively reduce the dynamic tire load and improve the suspension smoothness and road friendliness.

Analysis of the running quality and road friendliness of the virtual track train in multiple running stages between stations

Analysis of the running quality and road friendliness of the virtual track train in multiple running stages between stations

Design and test of hydro-pneumatic ISD suspension in heavy multi-axle vehicles

Aiming to improve the road friendliness so as to reduce the road damage caused by heavy multi-axle vehicles, and to enhance the ride comfort, we propose a kind of hydro-pneumatic ISD suspension structure, which is equivalent to a two-stage ISD structure integrating a traditional hydro-pneumatic suspension and a fluid inerter. Firstly, based on the 1/4 model, a genetic algorithm is used to optimize the key structural parameters of hydro-pneumatic ISD suspension. Secondly, the AMESim dynamic model of heavy multi-axle vehicles is built for the performance comparison between the traditional hydraulic and hydro-pneumatic ISD suspensions. Finally, this paper machines a hydro-pneumatic ISD suspension to replace the traditional hydraulic one in a heavy multi-axle vehicle to carry out a road test. Test results indicate that the proposed suspension can effectively restrain the vibrations of sprung and unsprung mass and improve ride comfort as well as road friendliness. The hydro-pneumatic ISD suspension can be applied to engineering.

Study on adverse effect suppression of hub motor driven vehicles with inertial suspensions

With increasingly severe energy supply and environmental pollution, Hub Motor Driven Vehicle (HMDV) have become the ideal configuration for future electric vehicles. The adverse effect caused by the significant increase in HMDV unsprung mass directly affects the vehicle ride comfort and handling stability, becomes a technical bottleneck for theoretical research and industrial development to be solved urgently. The HMDV adverse effect should be suppressed by the vehicle suspension system, which can be classified as vertical motion inertia instability caused by the increase of unsprung mass, but the lack of inertial elements in the conventional suspension “damping-spring” structure restricts the overall performance of the suspension. Therefore, the inertial suspension containing the inertial element “inerter” is utilized to effectively distribute the HMDV vertical motion inertia to suppress its adverse effects. First, the adverse effects of increased unsprung mass on vehicle ride comfort and road friendliness are studied. Then, the inertial suspension models of different structures are established and their impedance expressions are derived. Thirdly, the impact of the inertance in the inertial suspension on the suppression of the HMDV adverse effect is studied. Finally, the particle swarm optimization algorithm is utilized to optimize the parameters of the inertial suspension to improve the performance of the suspension. The results show that the inertial suspension can reduce the RMS value of body acceleration and dynamic tire load. The RMS value of body acceleration and dynamic tire load of the L4 structure is reduced by 8.1% and 16.38% respectively. It shows that the inertial suspension can effectively suppress the HMDV vertical adverse effect, improve the HMDV ride comfort and road friendliness, and lay the foundation for the subsequent suppression research.

Control of the air suspension system of semi-trailer trucks to enhance the road friendliness

An air suspension system of semi-trailer trucks controlled by semi-active fuzzy logic control is proposed and researched to reduce the dynamic load coefficient (DLC) of the wheel axles. A dynamical model described by a nonlinear system with 7-DOF of the vehicle and a Simulink program developed in Matlab software are applied to simulate the DLC values under different operation conditions. The fuzzy control is then applied to control damping coefficients of the air suspension system. The obtained results show that semi-active air suspension of semi-trailer truck is overall superior to passive air suspension. The DLC values are also significantly decreased in all cases of the road surface roughness, over a range of vehicle velocity and the different loaded conditions. Particularly, under vehicle fully loaded condition, the DLC value of the tractor driver is greatly reduced by 27.4 % at speed of 27.5 m/s on the ISO level B road.

Optimal design parameters of air suspension systems for semi-trailer truck. Part 2: results and discussion

Based on the results of model and algorithm in Part1 for searching the optimal design parameters of vehicle suspensions using genetic algorithm, in Part 2, the simulation results with MATLAB Simulink combined with an optimal program are written to search the optimal design parameters of vehicle air suspension systems in two optimal conditions. The optimal results indicate that the DLC values at all axles of vehicle respectively reduce by 9.09 %, 10.71 %, 11.11%, 10.81 %, 8.82 % (in Case 1) and 14.29 %, 19.23 %, 20.00 %, 17.14 %, 12.12 % (in Case 2) in comparison with the original air suspension systems when vehicle moves on the ISO class C road surface at v= 20 m/s and full load. All these things indicate that using the genetic algorithm optimization method does not only reduce the tire dynamic loads acting on road surface but also improves the ride comfort. Finally, the optimum performance of vehicle suspension systems is considered and reassessed under different operating conditions. The evaluation results indicate that the optimum performance of the air suspension systems has better potential to improve the road friendliness which provides a ride comfort for road surfaces and vehicle.

Dynamic performance analysis and parameters perturbation study of inerter–spring–damper suspension for heavy vehicle

Inerter, a new type of mass element, can increase the inertia of motion between two endpoints. In order to study the dynamic inertia effect of inerter–spring–damper suspension for heavy vehicle on ride comfort and road friendliness, the inerter–spring–damper suspension is applied and its mechanism is studied. This paper establishes a half vehicle model of inerter–spring–damper suspension for heavy vehicle. The parameters of inerter–spring–damper suspension for heavy vehicle are optimized by multi-objective genetic algorithm and system simulations are carried out. The parametric influence of different spring stiffness, damping coefficient, inertance, and load on suspension performance is also studied. The simulation results demonstrate that the centroid acceleration and pitch angular acceleration are improved by 24.90% and 23.54%, respectively, and the comprehensive road damage coefficient is reduced by 4.05%. The results illustrate that the inerter–spring–damper suspension can decrease the vertical vibration of vehicle suspension especially in low frequency and reduce the road damage. The analyses of suspension parameters perturbation reveal their different effect laws of the different wheels on vehicle ride comfort and road friendliness, which provide a theoretical basis for setting parameters of inerter–spring–damper suspension.

高地隙自走式喷雾机底盘空气悬架设计与混合滑模控制研究

According to the operation characteristics of high clearance self-propelled sprayer, an independent vertical shaft air suspension system with auxiliary chamber was designed. On the basis of the damping characteristic analysis and experiment of the air suspension with auxiliary chamber, the sprayer suspension control strategy was developed. Aiming at strong non-linearity and hysteresis for air suspension with auxiliary chamber, and when the sprayer performed road transportation and spraying operation, there was a contradiction between ride comfort and road friendliness, a hybrid sliding mode control method for sprayer chassis suspension based on skyhook reference sliding mode and ground-hook reference sliding mode was proposed. Finally, Matlab/Simulink was used to analyse the effect of the control method in different mixing coefficients. The simulation results showed that according to the requirements of different working conditions of the sprayer, by properly selecting the mixing coefficient γ value, the hybrid sliding mode control could simultaneously take into account the sprayer ride comfort and road friendliness, which was important to improve the sprayer overall performance and operating efficiency.

Analysis of the Influence of Characteristic Parameters of Heavy Vehicle Front Suspension to Road Friendliness Based on Virtual Excitation

Analysis of the Influence of Characteristic Parameters of Heavy Vehicle Front Suspension to Road Friendliness Based on Virtual Excitation

Research on the Analysis of the Influence of Characteristic Parameters of Heavy Vehicle Front Suspension to Road Friendliness Based on Virtual Excitation

Research on the Analysis of the Influence of Characteristic Parameters of Heavy Vehicle Front Suspension to Road Friendliness Based on Virtual Excitation

Evaluating the effect of the working conditions on the ride comfort and road friendliness of the heavy truck

This study proposes a nonlinear dynamic model of the heavy trucks to evaluate the influence of the various working conditions on the ride comfort and road friendliness of the heavy vehicles based on Matlab/Simulink software. The weighted root mean square (RMS) acceleration responses of the vertical driver’s seat, the cab’s pitch and roll angles, and the dynamic load coefficient (DLC) are chosen as objective functions. The influence of the vehicle velocity and loads on the different road surfaces are evaluated based on the standard ISO 2631-1. The results show that the vehicle’s ride comfort is clearly affected on the road surfaces of ISO level C and D at the range of the vehicle velocity. Especially, the vehicle’s ride comfort is very poor at the velocity of 10-30 m.s-1 on ISO level D. The road friendliness of the vehicle is greatly decreased in the condition of the half-loaded vehicle. Particularly the vertical dynamic wheel loads at 2nd axle strongly affect the road damage at the velocity of 10-30 m.s-1.

Construction of Three‐Dimensional Road Surface and Application on Interaction between Vehicle and Road

The quantitative description is given to three‐dimensional micro and macro self‐similar characteristics of road surface from the perspective of fractal geometry using FBM stochastic midpoint displacement and diamond‐square algorithm in conjunction with fractal characteristics and statistical characteristics of standard pavement determined by estimation method of box‐counting dimension. The comparative analysis between reconstructed three‐dimensional road surface spectrum and theoretical road surface spectrum and correlation coefficient demonstrate the high reconstruction accuracy of fractal reconstructed road spectrum. Furthermore, the bump zone is taken as an example to reconstruct a more arbitrary 3D road model through isomorphism of special road surface with stochastic road surface model. Measurement is taken to assume the tire footprint on road surface to be a rectangle, where the pressure distribution is expressed with mean stiffness, while the contact points in the contact area are replaced with a number of springs. Two‐DOF vehicle is used as an example to analyze the difference between three‐dimensional multipoint‐and‐plane contact and traditional point contact model. Three‐dimensional road surface spectrum provides a more accurate description of the impact effect of tire on road surface, thereby laying a theoretical basis for studies on the dynamical process of interaction of vehicle‐road surface and the road friendliness.

Modelling and analysis of parallel-interlinked air suspension system based on a transfer characterisation

This paper focuses on the transferring characteristic and the matching method for interlinked air suspension. Firstly, a structure analysis of parallel air suspension system is given. According to gas thermodynamics and vehicle dynamics, the half vehicle model of the parallel-interlinked air suspension is built. Secondly, the nonlinear dynamic model is linearised by using Taylor series expansion. A comparison analysis of different suspension characteristics between the interlinked and non-interlinked air suspension is carried out. Finally, an experimental study is conducted to validate the simulation results. We found that parallel interlinked air suspension has little effect on the acceleration of the vehicle body during the straight-line driving condition. Most meaningfully, interlinked air suspension could significantly decrease the amplitude of roll angle, which is an important characteristic of the attitude stability. Moreover, the proposed interlinked air springs can reduce the dynamic load of unsprung mass, and improve the road friendliness of vehicles.