Comfort Of Vehicle Research Articles

Application Layer Software Design of Vehicle Comfort Braking Based on Brake-by-Wire System

With the development of the brake-by-wire system, more and more advanced driver assistance systems have been applied to automobiles. The brake-by-wire system can collect the driver’s braking intention through the displacement sensor and thus realize accurate braking by the motor. Based on the brake-by-wire system, we design an algorithm that can realize the vehicle Comfort Stop Technology (CST) in this paper. The CST can control the drop and rise of brake fluid pressure during the braking stop of the vehicle, and therefore reduce the sharp feeling of front and back pitching during the braking stop. Finally, through real car verification, the functional algorithm designed in this paper can improve the nodding feeling of the vehicle by reducing the deceleration of the vehicle during braking.

Development of a novel hybrid method to evaluate driving comfort in an all-terrain vehicle using transfer path analysis and transfer function analysis

Vehicle comfort has become a buzzword in the automobile sector and continuous research is going on in this domain. Every automobile manufacturer would like to take the lead in vehicle comfort so as to attract more customers. Noise, vibration and harshness (NVH) testing is very important for improving the driving comfort of a vehicle. Driving comfort is directly related to the driving ability and health of the driver. Many international organisations have laid down guidelines for measuring driving comfort and categorise it in a range from comfortable to extremely uncomfortable. The present study adopts an experimental approach to determine the driving comfort in all-terrain vehicles (ATVs) by measuring frequency-weighted root-mean-square (RMS) accelerations at all the driver contact points in three mutually perpendicular directions as per the guidelines laid down in ISO 2631-1:1997 and ISO 5349-1:2001. The low-amplitude high-frequency engine vibrations are attenuated by performing transfer path analysis (TPA) of the vehicle roll cage before and after design modifications. The performance of the engine isolator mount is evaluated by carrying out transfer function analysis (TFA) of the active and passive engine mount vibrations. A novel hybrid approach comprising the TPA and TFA methods is used to attenuate the engine vibrations. The test result shows the effectiveness of the design modifications at the footrest, whereas there is moderate to low effectiveness at the steering and seat, respectively.

Dynamic modeling and ride comfort evaluation of railway vehicle under random track irregularities: A case study of a Linke-Hofmann-Busch coach

The ride comfort of passengers is an important parameter for evaluating the performance of railway vehicles. Many standards/ models, such as quarter car, half car, and full car, have been proposed to evaluate the human comfort of railway vehicles. However, a full-scale coupled railway vehicle model is rarely considered for calculating ride comfort. Therefore, this paper proposes a twenty-seven-degree-of-freedom (27-DOF) coupled dynamic model of railway vehicles integrated with wheel-rail contact forces. The developed model is solved using the two-dimensional (2-D) state space method, and the effects of different track irregularities on human comfort are evaluated. The outputs are described in terms of three-dimensional (3-D) Power Spectral Densities (PSDs) under three types of random track irregularities: vertical profile, lateral alignment, and cross-level. Furthermore, Sperling's method is used to evaluate the human comfort index. For the case study, a Linke-Hofmann-Busch coach (LHB) based model has been employed, and the results are validated with the experimental data of ride comfort reported by the Research Design and Standard Organization (RDSO). The simulated results of the proposed model demonstrate a remarkable alignment with the experimental data, exhibiting a small error ranging from 2.36 % to 8.81 % for vertical motion and 5.84 % to 8.30 % for lateral motion, respectively. Such promising results offer valuable insight for the design of future coaches, ensuring enhanced ride comfort even at high speeds.

Evaluating the Isolation Performance of Three Seat Suspension Models of Off-Road Vehicles

<div>Three suspension structures including the parallel vertical suspension (PVS), the horizontal parallel suspension (HPS), and the negative stiffness element added into suspension (NSES) of the driver’s seat are proposed to improve the driver’s ride comfort of off-road vehicles. Based on the dynamic models of the PVS, HPS, and NSES established and simulated under the same random excitations of the cab floor, the effect of the design parameters of the proposed models is analyzed, and the design parameters are then optimized to evaluate their isolation performance. The indexes of the root-mean-square (r.m.s) accelerations of the vertical seat direction, pitching seat angle, and rolling seat angle are used as the objective functions. The study results indicate that the dynamic parameters of the PVS, HPS, and NSES greatly affect the driver’s ride comfort while their geometrical dimensions insignificantly affect the driver’s ride comfort. With the dynamic parameters of the PVS, HPS, and NSES optimized, the r.m.s seat acceleration in the vertical direction with the NSES is strongly reduced by 74.0% in comparison with the HPS; while the r.m.s accelerations of the pitching seat angle and rolling seat angle with the PVS are greatly decreased by 99.1% and 99.8% compared to the NSES. Therefore, the ride comfort of the driver’s seat is remarkably improved by using the NSES while the driver’s seat shaking is obviously ameliorated by using the PVS. To enhance the ride comfort and reduce the shaking of the driver’s seat, a combination of the PVS and NSES should be applied to the seat suspension of off-road vehicles.</div>

Tire and Engine Sources Contribution to Vehicle Interior Noise and Vibration Exposure Levels

The main objective of the research presented in this paper is to enhance driver-passengers comfort of a vehicle that in turn leads to better vehicle safety and stability. The focus was put on studying the interior vibration and noise contributions originated from tire-road and engine-transmission subsystems, due to their significant impact on the dynamic performance of the vehicle. The noise and vibration measurements were recorded at the driver’s head position and on the driver legs room. Furthermore, the influence of different tire types and road surface textures on the vehicle interior noise and vibration were considered. The results indicate that the widely used conventional engine mounts and tires in commercial vehicles cannot fulfill the conflicting requirements for the best isolation concerning both road surface and engine-transmission induced excitations. The values of driver’s head position sound pressure level and floor vibration acceleration broadband averages originate for engine-transmission are lower than that for tire-road interaction. Furthermore, the values of RMS, crest factor, kurtosis and IRI for the vehicle waveform were estimated for vehicle speeds, tire types and road surface textures. Moreover, the percentage contribution for both interior noise and vibration originated from tire-road interaction is higher than the one from vehicle engine-transmission system in all the vehicle speed range, tire type and road surface texture considered.

Improved Vehicle Vibration Control through Optimization of Suspension Parameters Using the Response Surface Method and a Non-Linear Programming with a Quadratic Lagrangian Algorithm

Vibration-control techniques generally fall into two categories: passive methods that optimize the structure of the suspension to absorb any impact from the ground, and active methods that directly control the vertical force of the suspension by hydraulic or electric actuators when the vehicle traverses a bumpy road. In this study, a vibration-control method is described that employs both an optimal controller and suspension parameter optimization. Continuous speed bumps are implemented to simulate more complex and realistic driving conditions. First, a vehicle system is modeled using a semi-recursive multibody formulation, which allows for a more precise description of the longitudinal–vertical dynamics. Then, an optimal control method for vehicle vibration control is introduced. Second, the Latin hypercube design is utilized to analyze the response surface methodology (RSM) model. For suspension optimization, the RSM model and the non-linear programming with a quadratic Lagrangian (NLPQL) algorithm are employed. Thirdly, both passive suspension optimization and active motion control are employed for vibration control. The results indicate that the presented method can effectively control vehicle vibration, decreasing the average vibration by 30.8%. The results suggest that the novel approach can also enhance the ride comfort in autonomous vehicles traversing, e.g., a series of speed bumps.

Multi-objective optimization of safety, comfort and economy of hybrid electric vehicle in car-following scenario

ABSTRACT The energy management strategy (EMS) of hybrid electric vehicle (HEV) is the key to optimize the energy conversion performance of the whole vehicle power system. The performance of EMS could be affected by vehicle parameters such as vehicle speed, battery state of charge (SOC) and the environmental parameters including the current following state jointly. Combining the following state of the vehicle with EMS can be beneficial to improve the road performance of HEV. In this paper, a multi-objective optimization framework for safe following, comfort and fuel economy of HEV is established based on model predictive control (MPC) under both urban and high-speed conditions, and the kinematic parameter of the preceding vehicle was predicted on the basis of third-order Markov model. Simulation tests including urban and high-speed working condition are carried out respectively and results show that the following vehicle maintains expected following safety and comfort. Meanwhile, compared to the typical rule-based strategy and equivalent consumption minimum strategy (ECMS), the fuel economy has also been increased by 29.8% and 9.2% in UDDS working condition, 25.2% and 6.1% in WLTC working condition, respectively.

Enhanced variable universe fuzzy PID control of the active suspension based on expansion factor parameters adaption and genetic algorithm

The optimal value of the expansion factor and quantization factor parameters is the key to determine the performance of the variable domain fuzzy proportion-integral-derivative (PID) controller. In view of the problem that the relevant parameters are fixed, difficult to determine and cannot be adjusted adaptively in the traditional variable domain fuzzy PID control, a kind of enhanced variable domain fuzzy PID control (EVUFP) is proposed to improve the ride comfort of vehicles. First, based on the traditional variable domain fuzzy PID control, an adaptive expansion factor controller is constructed to determine and adjust adaptively the parameters of the expansion factor in real time. Then the genetic algorithm is used to optimize the quantization factor and scale factor parameters to seek the optimal value of relevant parameters. And the obtained optimal parameters are substituted into the Simulink model to realize the design of the EVUFP controller. The simulation experiment results under different working conditions show that the proposed EVUFP control strategy can reduce the root mean square (RMS) values of the body acceleration, suspension dynamic deflection and tire dynamic load by more than 54%, 50% and 23%, respectively, improve the ride comfort of vehicles, and provide a new idea for the development of active suspensions.

A Review of the Motion Planning and Control Methods for Automated Vehicles.

The motion planning and control method of automated vehicles, as the key technology of automated vehicles, directly affects the safety, comfort, and other technical indicators of vehicles. The planning module is responsible for generating a vehicle driving path. The control module is responsible for driving the vehicle. In this study, we review the main methods and achievements in motion planning and motion control for automated vehicles. The advantages and disadvantages of various planning and control methods are comparatively analyzed. Finally, some predictions and summaries based on the existing research results and trends are proposed. Through this analysis, it is believed that various types of algorithms will be further integrated in the future to complement each other's strengths and weaknesses. The next area of research will be to establish more accurate vehicle models to describe vehicle motion, improve the generalization-solving ability of algorithms, and enhance the planning and control of integrated 'human-vehicle-road' traffic systems.

A Human-Machine Shared Control Framework Considering Time-Varying Driver Characteristics

The uncertainties of driver's behavior seriously affect road safety and bring significant challenges to the human-machine cooperative control. This paper proposes a human-machine shared control framework considering driver's time-varying characteristics to improve the co-driving cooperation performance. Firstly, the driving intention is introduced to describe the driver's involvement level through using Gauss-Bernoulli restricted Boltzmann machine method. And the index of driving ability is proposed to evaluate driver skills based on path-tracking errors. Then, a novel human-machine authority allocation strategy is designed by combining the two driving behavior characteristics and used to construct the driver-vehicle interaction system. Subsequently, a T-S fuzzy robust state-feedback shared control system is developed considering time-varying driver behaviors and vehicle states. Finally, the proposed shared steering system is validated by the driver-in-the-loop test bench. The results show that the proposed control method can reduce human-machine conflicts and has obvious superiority in improving performance of driving comfort, path tracking, and vehicle stability for the co-driving vehicles.

Adaptive Cruise System Based on Fuzzy MPC and Machine Learning State Observer

Under the trend of vehicle intelligentization, many electrical control functions and control methods have been proposed to improve vehicle comfort and safety, among which the Adaptive Cruise Control (ACC) system is a typical example. However, the tracking performance, comfort and control robustness of the ACC system need more attention under uncertain environments and changing motion states. Therefore, this paper proposes a hierarchical control strategy, including a dynamic normal wheel load observer, a Fuzzy Model Predictive Controller and an integral-separate PID executive layer controller. Firstly, a deep learning-based dynamic normal wheel load observer is added to the perception layer of the conventional ACC system and the observer output is used as a prerequisite for brake torque allocation. Secondly, a Fuzzy Model Predictive Control (fuzzy-MPC) method is adopted in the ACC system controller design, which establishes performance indicators, including tracking performance and comfort, as objective functions, dynamically adjusts their weights and determines constraint conditions based on safety indicators to adapt to continuously changing driving scenarios. Finally, the executive controller adopts the integral-separate PID method to follow the vehicle’s longitudinal motion commands, thus improving the system’s response speed and execution accuracy. A rule-based ABS control method was also developed to further improve the driving safety of vehicles under different road conditions. The proposed strategy has been simulated and validated in different typical driving scenarios and the results show that the proposed method provides better tracking accuracy and stability than traditional techniques.

Study on Multi-Mode Switching Control of Intelligent Suspension under Full Road Section

The safety, comfort, and energy feedback of active suspension in a single control mode is mutually restricted. To meet the needs of drivers and passengers for vehicle driving performance under different road conditions, this paper proposes a multi-mode switching control strategy of an intelligent suspension system, aiming at improving the stability and comfort of vehicles under different road conditions. In this paper, the adaptive Kalman filter algorithm with a forgetting factor is used to estimate the road input. The accuracy of the algorithm in estimating the road input is verified by simulation and experiment. The single-double threshold logic judgment method is used to formulate the switching rules between each working mode. In the controller, the PID control of the BP neural network and the LQR control optimized by GA are used to optimize and adjust the vehicle driving performance indexes in different modes, which effectively solves the problem of limited adaptability of suspension control optimization objectives under different road driving conditions. Based on the data from the vehicle acceleration sensor and road condition sensor, the modeling and simulation of the switching control system are carried out. The simulation results show that the designed control system can effectively improve the comprehensive performance of the vehicle under different road driving conditions. Compared with the traditional active suspension, the body acceleration is increased by 26% on the B-grade road surface, which effectively improves the user’s ride comfort. Compared with the traditional active suspension, the tire dynamic displacement is increased by 24% on the D-grade road, which can significantly improve the overall performance of the vehicle and meet the design requirements of the system.

Radiation Effect on Heat Transfer in Narrow Cavities

The thermal comfort and air-conditioning energy consumption of vehicles or trains are dependent on the thermal resistance of its envelopes, which could be enhanced by improving the radiation characteristics of the narrow cavities scattered in their envelopes. However, the study for a feasible method and its effectiveness has been given little attention. This paper introduces a method that involves pasting aluminum foil on the inner wall to change the radiation characteristics of the narrow cavity and analyzed its effects on narrow-cavity heat transfer by experimental and numerical methods. The results indicate that the radiation effect on heat transfer in a narrow cavity made of conventional material is dominant, with a rate larger than 75%, and that pasting aluminum foil is an effective and feasible method of weakening the radiation rate in narrow-cavity heat transfer, decreasing it to less than 10%. This paper will provide a reference to improve the insulation characteristics of vehicle enclosure.

Influence analysis of dynamic changes of wheel alignment parameters on high-speed rocking vibration of steering wheel

The control of high-speed rocking vibration of steering wheel is very important for vehicle comfort performance. Among vibration control methods, the reasonable design of wheel alignment parameters is the most effective method. At present, the alignment parameters are obtained through quasi-static test. However, under high-speed driving conditions, the wheel alignment parameters change dynamically, which intensifies the vibration of the steering wheel. Therefore, it is more meaningful to study and control the dynamic characteristics of wheel alignment parameters. In order to analyze the dynamic characteristics of wheel alignment parameters and the problem of high-speed rocking vibration of steering wheel, the method of dynamic identification and dynamic control of alignment parameters is presented in the paper. By controlling the wheel dynamic unbalance and lateral force variations, the dynamic variation of the toe angle is significantly reduced, which reduces the vibration of the steering wheel.

Thermal performance evaluation of a compact two-fluid finned heat exchanger integrated with cold latent heat energy storage

To alleviate the mismatch between thermal energy supply and demand, the use of latent heat thermal energy storage of phase change materials is a reliable and effective solution in thermal systems. The present work aims to introduce an innovative finned-plate air-liquid heat exchanger with phase change material partially embedded in the fins' gap providing airside cooling by thermal energy storage during coolant shutdown periods. The thermal performance and accompanying phase change process are studied using a three-dimensional computational fluid dynamic approach. The developed model is validated with corresponding experimental data at the same geometry and operating conditions. The system performance is examined time-dependently considering the charging/discharging processes of the phase change material. The effect of air mass flow rate variation is studied, and the results are discussed in terms of fluids temperature, heat transfer rates, and the phase change material phase transition process. The results demonstrate that the heat exchanger stores excess thermal energy during the charging process, which is later discharged for air cooling during demand periods. It is observed that the use of phase change material provides a cooling load of 188 kJ and over 9 min of extra cooling time for the airside in the discharging process. The share of latent heat transfer in the discharging process is calculated at an average of 54% of the total heat transfer. Obtained results reveal that increasing the air mass flow rate can reduce the rate of discharged cold thermal energy and cooling time. The presented thermal management system offers a unique solution to manage passenger thermal comfort in hybrid and electric vehicles with a start-stop function. The introduced system could provide efficient cabin air cooling and enable effective energy savings during short periods of engine shutdown.

Shimmy analysis of straddle-type monorail vehicle with single-axle bogies based on factor model

Shimmy is one of the important factors affecting the ride comfort and lateral stability of straddle-type monorail vehicles with single-axle bogies (SMVS). To obtain the main parameters affecting SMVS shimmy, a global sensitivity analysis strategy for SMVS shimmy is proposed. The shimmy response surface model is constructed, and the sensitivity analysis of the shimmy response surface model is carried out by the Sobol method. Based on this, the shimmy factor model of SMVS is established by factor analysis method. A novel SMVS shimmy analysis method based on factor model is proposed. The shimmy factor model is verified by the dynamic model of SMVS. The results show that 11 main factors affecting the shimmy are obtained by sensitivity analysis. Through the dimension reduction technology of factor analysis, four main factors affecting SMVS shimmy are extracted. The complex coupling relationship between the shimmy factors of SMVS is revealed. The established shimmy factor model can effectively analyse the shimmy state of SMVS, and the dynamic simulation results also show consistency. This study not only proposes a new perspective to understand the SMVS shimmy mechanism, but also provides the foundation for further optimal design of monorail vehicle stability.

Hopf-curve-based torque distribution strategy for avoiding limit cycle vibration in hybrid braking system model

Limit cycle vibration affects ride comfort and safety of electric vehicle. In the present study, a Hopf curve was proposed for development of brake torque distribution strategy to circumvent limit cycle vibration. The stability and bifurcation conditions were evaluated based on brake-driveline coupling model of the hybrid braking system. The limit cycle vibration was predicted through the boundary between stable and unstable equilibrium regions. The findings showed that the limit cycle vibration was circumvented by tuning the hydraulic braking force based on the Hopf curve. The insufficient braking torque caused by the decrease in hydraulic braking force was compensated by the driven motor. The findings of the present study provide information on the passive suppression of limit cycle vibration in hybrid braking system to improve the comfort of electric vehicles.

Investigation of Vertical Stiffness of the Front Axle Air Springs for Passenger Bus by Experimental and Finite Element Analysis

Air Springs have been used for years, especially in commercial vehicles and buses, to maintain the vehicle's height regardless of the load and increase vehicle comfort. It is complex to experimentally determine the changes (reaction force, extension, strain) caused by loading alone to fully interpret the damping ability of air springs under operating conditions. The air springs are exposed to tension and force in different directions as they are made of a rubber composite structure. Therefore, discussing the damping properties of air springs with only the experimental method is difficult. The study aims to obtain information about the damping behavior of the bellows produced from composite materials, such as bellows under static loads, using both experimental and finite element analysis models. The finite element model of the air springs was obtained by modeling the three parts that provide its integrity. The material definitions required for the composite structure were determined by experimental methods and entered into the FEA program. No material is defined for rigid body members. The results of unidirectional and multidirectional tensile tests performed in a laboratory environment were used for material properties. The characteristics of the air were also entered into the analysis software with the information taken from the literature. The analyzes were carried out in three steps inflating the bellows to the specified pressure values, vertical movement, and compression to the specified displacement value. In this study, it was seen that the cord fabrics in rubber composite structures were affected more by excessive tension than rubber material, and the deviation of the static stiffness value was approximately 5% between the experimental study and the analysis studies. Thanks to FEA studies, it has been determined that more results can be obtained regarding values such as regional stress, force, and displacement in the bellows.

Aerodynamics and Drag of a Car

According to Chinese economic development and human life improvement, the vehicle, as the most important transportation, goes into common people’s life gradually. The following problems of energy are highlighted day by day. In Chinese Manufacturing 2025, the idea of energy-saving and new energy vehicle was pointed out as an important development area, and energy-saving and emission reduction had already been the core work content for Original Equipment Manufacturers. Aerodynamic performance has great influence to vehicle handling performance, power performance, fuel and economy. The external flow filed character better or not will all impact vehicle comfort performance directly. Therefore, OEMs paid more and more attention to vehicle aerodynamic simulation analysis. Reasonable aerodynamic performance plays an important role in improving the performance of vehicle dynamics, economy and so on. Therefore, how to meet the requirements of modeling, engineering at the same time, but also to improve aerodynamic characteristics is particularly important for design a car. This paper discusses the factors that affect the air resistance of the car.

Pedestrian Avoidance Method Considering Passenger Comfort for Autonomous Personal Mobility Vehicles

During the autonomous navigation of personal mobility vehicles (PMVs) in pedestrian spaces, avoiding collisions with pedestrians walking nearby is necessary. The avoidance paths of PMVs are affected by the behaviors of the pedestrians, which may also affect passenger comfort. Herein, a local path-planning method that considers passenger comfort to realize comfortable pedestrian avoidance during the autonomous navigation of PMVs in pedestrian spaces is proposed. First, the avoidance path and pedestrian behavior parameters affecting passenger comfort are investigated by evaluating passenger comfort in scenarios with different avoidance paths and pedestrian behaviors. Next, the requirements of a pedestrian avoidance method that considers passenger comfort are set based on the parameters affecting passenger comfort. Finally, a novel path-planning method that satisfies the requirements is proposed. The method is shown to generate comfortable paths in pedestrian spaces via a numerical simulation and participant experiment.