Sport Utility Vehicle Research Articles

Robust Continuous Wheel Slip Control With Reference Adaptation: Application to the Brake System With Decoupled Architecture

Modern and coming generations of electric and automated vehicles are characterized by higher requirements to robust and fault-tolerant operation of chassis systems independently from driving situations and road conditions. In this regard, this paper introduces an adaptive continuous wheel slip control (WSC) developed for the sport utility vehicle equipped with a high-dynamic decoupled electrohydraulic brake system. The system architecture, mathematical formulation of the WSC and state estimator as well as the experimental WSC validation is described in this paper. The focus is given on three continuous WSC strategies based on proportional integral (PI), sliding-mode PI and integral-sliding-mode control techniques. The proposed WSC also includes the state and parameter estimator for the adaptation of the reference wheel slip depending on current road conditions and using the standard on-board vehicle sensors and extremum-seeking algorithm. Adaptability and robustness of all WSC configurations were confirmed by the road experiments performed on low- and high- $ \mu$ surfaces with mandatory condition of the same controls adjustments for all test cases. Tests show an enhancement of the vehicle safety and ride quality, compared to the vehicle with the rule-based WSC control.

A New Method for Active Cancellation of Engine Order Noise in a Passenger Car

This paper presents a novel active noise cancellation (ANC) method to reduce the engine noise inside the cabin of a car. During the last three decades, many methods have been developed for the active control of a quasi-stationary narrowband sinusoidal signal. However, since the interior noise signal is non-stationary with a fast frequency variation when the car accelerates rapidly, these methods cannot stably reduce the interior noise. The proposed method can reduce the interior noise stably even if the speed of the car is changed quickly. The method uses an adaptive filter with an optimal weight vector for the active control of such an engine noise. The method of determining the optimal weight vector of an adaptive filter is demonstrated. In order to validate the advantages of the proposed method, a conventional method and the proposed method are simulated with three synthesized signals. Finally, the proposed method is applied to the cancellation of booming noise in a sport utility vehicle. We demonstrate that the performance of the ANC system with the proposed algorithm is excellent for the attenuation of engine noise inside the cabin of a car.

Lateral friction demand on roads with coincident horizontal and vertical sag curves

Rural highway crash analyses have shown that the majority of accidents occur on horizontal curves where the vehicle is exposed to lateral forces, which increase the probability of skidding. Moreover, in cases of compound alignments where curves from the road's horizontal alignment are overlaid with constant grades or vertical curves, the probability of skidding increases due to the increase of the longitudinal force on the vehicle. In this research, by utilising vehicle multi-body simulation modelling, several scenarios are defined to assess the impact when horizontal curves are combined with vertical sag curves for three different kinds of vehicles (sedan, sports utility vehicle and truck). For various speed values, the maximum lateral friction demand between the road surface and vehicle tyres is calculated. Finally, by using regression analysis, a model is presented according to the inputs and outputs of the simulation modelling to determine the maximum lateral friction demand created in various conditions. The results of this research indicate that the maximum lateral friction between the road surface and vehicle occurs when the lower part of the sag vertical alignment is located in the middle of horizontal curve.

The rebound effect of the Australian proposed light vehicle fuel efficiency standards

Australia is planning to take action to tackle climate change via improvements in light vehicle fuel efficiency. The proposed light vehicle emissions standards are expected to reduce petroleum use as well as greenhouse gas emissions from passenger vehicles, sports utility vehicles and light commercial vehicles. Consumers of light vehicles, including private households and firms, will respond to this policy in a way that maximise their utility based on economic theory. On one hand, these economic agents will use less petrol, through directly purchasing more efficient new cars to react to the mandatory standard. On the other hand, the more efficient vehicle will provide an incentive for the consumers to use it more as the effective cost of driving decreases. Understanding these economic and behavioural responses to the policy is crucial for policymakers. This paper contributes to the empirical studies of the rebound effect by simulating the business-as-usual (BAU) and policy scenarios in a computable general equilibrium framework. The direct rebound effect of the Australian proposed light vehicle fuel efficiency standards are shown to range between 25 per cent and 30 per cent, measured by petroleum use. Each of these policy scenarios is shown to have a much larger economy-wide rebound effect, reaching up to 50 per cent measured by life-cycle greenhouse gas emissions. Although the stringent fuel efficiency standard generates more direct rebound effects measured in percentage than the lenient and medium standards, the stringent policy produces the most reduction in carbon emissions measured in physical units overall. This paper concludes by providing comprehensive understanding of the Australian proposed light vehicle fuel efficiency standards and offering policy recommendations based on the CGE simulation results.

Understanding the association between cell phone use while driving and seat belt noncompliance in Qatar using logit models

ABSTRACTCell phone use while driving can distract the driver and can lead to serious traffic safety problems. Similarly, not using a seat belt can increase the risk of injuries and/or fatalities in the event of a crash. The objective of this study is to identify the rate of cell phone use as well as the rate of seat belt noncompliance in Qatar and to investigate the association between the two. A total of 7,982 vehicles were observed at 40 intersections. The overall rate of seat belt noncompliance was 16.4%, and the overall rate of cell phone use while driving was 10.7%. Logit models were developed to identify the factors that affect the use of cell phones and seat belts, and a significant association was found between the two. The results of the study show that people driving sport utility vehicles are less likely to wear seat belts than those using other types of vehicles and more likely to use their cell phones while driving. In addition, male drivers are more likely than female drivers to wear seat belts and less likely to use their cell phones while driving. Furthermore, young drivers are less likely to wear seat belts than older drivers and more likely to use their cell phones while driving. The results of this study can help policy makers and public agencies to understand the profiles of drivers who use cell phones while driving and who are also noncompliant with seat belt use. This information can help in identifying the proper countermeasures and the targeted population in both Qatar and similar countries in the region.

Parametric Study of Asymmetric Side Tapering in Constant Cross Wind Conditions

Copyright © 2018 SAE International. Sports Utility Vehicles (SUVs) often have blunt rear end geometries for design and practicality, which is not typically aerodynamic. Drag can be reduced with a number of passive and active methods, which are generally prioritised at zero yaw, which is not entirely representative of the “on road” environment. As such, to combine a visually square geometry (at rest) with optimal drag reductions at non-zero yaw, an adaptive system that applies vertical side edge tapers independently is tested statically. A parametric study has been undertaken in Loughborough University’s Large Wind Tunnel with the ¼ scale Windsor Model. The aerodynamic effect of implementing asymmetric side tapering has been assessed for a range of yaw angles (0°, ±2.5°, ±5° and ±10°) on the force and moment coefficients. This adaptive system reduced drag at every non-zero yaw angle tested, from the simplest geometry (full body taper without wheels) to the most complex geometry (upper body taper with wheels) with varying levels of success; providing additional drag reductions from 3% to 125%. The system also shows potential to beneficially modify the cross wind stability of the geometry.

Active flow control analysis at the rear of an SUV

PurposeThis paper aims to present an experimental investigation of an active flow control solution mounted at rear of a sport utility vehicle (SUV) with the objective of drag reduction, thanks to a selection of flow control parameters leading to a pressure increase on the tailgate.Design/methodology/approachA flow control design of experiments was conducted with a pulsed jet system mounted on the top and sides of the rear window of the vehicle. The wall pressure, instantaneous velocity and drag were measured with this prototype in a wind tunnel. A dynamic modal decomposition (DMD) analysis of the pressure enables to describe the pressure fluctuations. Fluid dynamic computations show relation between pressure and velocity fields.FindingsMeasurements with this prototype in the wind tunnel revealed small improvements in drag for the best flow control configurations. This small benefit is because of the core of the upper span wise vortex further away from the rear window than the lower span wise vortex. These small improvements in drag were confirmed with pressure measurements on the rear window and tailgate. The DMD analysis of the surface pressure showed a low frequency pendulum oscillation on the lower area of the tailgate, linked with low velocity frequencies in the shear layers near the tailgate.Originality/valueExperimental and numerical results show interest to increase pressure at bottom of the rear end of this SUV prototype. The dynamic description of the wall pressure shows importance of flow control solutions reducing pressure fluctuations at low frequencies in the lower area of the tailgate.

Simulation analysis and optimization of ride quality of in-wheel motor electric vehicle

In order to evaluate the influence of unsprung mass on ride comfort for an in-wheel motor electric vehicle, an improved genetic algorithm based on fitness evaluation was proposed to optimize the suspension system. The simulation model was established in ADAMS software for the target sports utility vehicle with front McPherson and rear unequal length double arm suspension systems. The ride comfort of the target vehicle was analyzed by the developed simulation model. The stiffness and damping of the suspensions were optimized by the root mean square values of the vehicle weighted vertical acceleration and the pitching angle acceleration with the help of the multi-disciplinary and multi-objective optimization software, ISIGHT. The results show that, the proposed multi-objective optimization algorithm is helpful to achieve the ride comfort improvement and the computation time reduction.

Comparative Analysis on Traumatic Brain Injury Risk Due to Primary and Secondary Impacts in a Pedestrian Sideswipe Accident

A series of pedestrian sideswipe impacts were computationally reconstructed; a fast-walking pedestrian was collided laterally with the side of a moving vehicle at 25 km/h or 40 km/h, which resulted in rotating the pedestrian's body axially. Potential severity of traumatic brain injury (TBI) was assessed using linear and rotational acceleration pulses applied to the head and by measuring intracranial brain tissue deformation. We found that TBI risk due to secondary head strike with the ground can be much greater than that due to primary head strike with the vehicle. Further, an “effective” head mass, meff, was computed based upon the impulse and vertical velocity change involved in the secondary head strike, which mostly exceeded the mass of the adult head-form impactor (4.5 kg) commonly used for a current regulatory impact test for pedestrian safety assessment. Our results demonstrated that a sport utility vehicle (SUV) is more aggressive than a sedan due to the differences in frontal shape. Additionally, it was highlighted that a striking vehicle velocity should be lower than 25 km/h at the moment of impact to exclude the potential risk of sustaining TBI, which would be mitigated by actively controlling meff, because meff is closely associated with a rotational acceleration pulse applied to the head involved in the final event of ground contact.

Speed prediction models for car and sports utility vehicle at locations along four-lane median divided horizontal curves

Sites with varying geometric features were analyzed to develop the 85th percentile speed prediction models for car and sports utility vehicle (SUV) at 50 m prior to the point of curvature (PC), PC, midpoint of a curve (MC), point of tangent (PT) and 50 m beyond PT on four-lane median divided rural highways. The car and SUV speed data were combined in the analysis as they were found to be normally distributed and not significantly different. Independent parameters representing geometric features and speed at the preceding section were logically selected in stepwise regression analyses to develop the models. Speeds at various locations were found to be dependent on some combinations of curve length, curvature and speed in the immediately preceding section of the highway. Curve length had a significant effect on the speed at locations 50 m prior to PC, PC and MC. The effect of curvature on speed was observed only at MC. The curve geometry did not have a significant effect on speed from PT onwards. The speed at 50 m prior to PC and curvature is the most significant parameter that affects the speed at PC and MC, respectively. Before entering a horizontal curve, drivers possibly perceive the curve based on its length. Longer curve encourages drivers to maintain higher speed in the preceding tangent section. Further, drivers start experiencing the effect of curvature only after entering the curve and adjust speed accordingly. Practitioners can use these findings in designing consistent horizontal curve for vehicle speed harmony.

Measuring the Passenger Car Equivalent of Small Cars and SUVs on Rainy and Sunny Days

Traffic volume is a fundamental measurement in traffic analyses. In mixed traffic, vehicles vary in size, length, headway, spacing, and acceleration/deceleration. Therefore, if we can categorize the vehicles in mixed traffic in greater detail, the estimated passenger car equivalent (PCE) number will be more accurate. Practical and appropriate methods that convert different vehicles into the equivalent number of passenger cars need to be employed to determine PCE factors for heterogeneous traffic. Following economic growth and increased use of motor vehicles in developing countries, the purchase of sports utility vehicles (SUVs) continues to grow, though the government encourages people to buy small cars because of the limited road capacity, as well as air pollution problems. In this research, we categorize passenger cars into three subsets: small cars (hatchback cars without a trunk), SUVs, and standard cars (taxis and typical family cars). A field investigation shows that the penetration rates of these passenger cars are 12%, 23%, and 55%, respectively (10% are other vehicles) in Hangzhou, China. We also measure the PCE value for small cars and SUVs using the mean time headway method. Because different countries have different weather conditions, we continue to measure the PCE values for sunny days and moderate rainy days. The results show that PCE values for small cars and SUVs are 0.87 and 1.26 on sunny days, and 0.87 and 1.31 on rainy days, respectively. By using the PCE with high precision, urban managers can accomplish the analysis of urban traffic with greater accuracy.

Traffic safety in an aging society: Analysis of older pedestrian crashes

ABSTRACTOlder pedestrians are a growing and vulnerable road user group. This article analyzes various driver, vehicle type, vehicle movement, location, and environment factors associated with older adult pedestrians (age 65+) in comparison with younger adult pedestrians (ages 18–59) using the 2012–2013 U.S. General Estimate Systems (GES) database. A random-effects logistic regression model, which captures regional heterogeneity, was used to classify pedestrian traffic crashes as either involving an older or a younger pedestrian to analyze the factors linked to older vs. younger adult pedestrians. The results show that the older the vehicle driver, the more likely the crash was to be classified as an older pedestrian crash. Improved street crossing environment and intersections, due to older adults' higher involvement in crashes with turning vehicles, are critical to promote older pedestrian safety. Pedestrian safety on nonroadways needs more attention because older pedestrian crashes are more likely in parking lots and driveways compared to younger pedestrians. The results show an especially negative impact of sport utility vehicles and minivans on older adult pedestrian safety. This is a concern because heavier and higher vehicles are more likely to cause greater injuries than smaller cars.

Best in Class or Simply the Best? The Impact of Absolute versus Relative Ecolabeling Approaches

Although research has widely investigated labels across a range of product domains, one understudied area is the use of absolute versus relative rating approaches to information provision. For example, under an absolute rating approach to vehicle ecolabels, the consumer is informed of the actual amount of fuel consumed during use of a vehicle compared with that of all other vehicles on the market. Under a relative rating approach, the fuel consumption is communicated in relative terms, comparing the vehicle only with others in the same class. The current research illustrates that switching from an absolute to a relative rating approach can lead to a reversal effect in the perception of a car's environmental friendliness. For example, a sport-utility vehicle can be perceived as either environmentally friendly or not, depending on the type of rating approach used. The authors demonstrate that visual representation drives this effect, using a colored alphabetical rating scale to communicate environmental performance.

Head, chest and femur injury in teenage pedestrian–SUV crash; mass influence on the speeds

This work studies the teenage pedestrian–sport utility vehicle (SUV) crash; injury to the vital parts of the body, such as the head and chest, and to the femur is evaluated. More advanced injury criteria are applied, as provided in the rules. The multibody technique is applied by making use of SimWise software and of the teenager anthropomorphic model, the use of which is now consolidated. Head injury criterion (HIC) is used for the head, thoracic trauma index (TTI) criterion for the thorax in the case of side impact and 3 ms criterion in the case of frontal impact, while the force criterion is used for the femur. Both the TTI and femur load evaluation require non-substantial modifications of the dummy, by insertion of sensors for the measurement of the acceleration of the 4th rib and the 12th vertebra and two very thin plates at the knees for the correct individuation of the contact point with the vehicle bumper. Particular attention is paid to the front shape of the vehicle, concluding that the SUV examined in this paper is less dangerous than the sedan studied in a previous work, since its frontal dimensions (bonnet angle, bumper height and bonnet height) are more advantageous. However the teenage pedestrian in a lateral position is less prone to injuries in the head and chest, with respect to the frontal position; the pedestrian’s position has little influence on femur damage. Furthermore, the braking of the vehicle reduces the possibility of crash fatality. In conclusion, a theoretical approach is shown, to highlight the influence of the vehicle mass on the pedestrian speed after the impact.

Performance Investigation of an Exhaust Thermoelectric Generator for Military SUV Application

To analyze the thermoelectric power generation for sports utility vehicle (SUV) application, a novel thermoelectric generator (TEG) based on low-temperature Bi2Te3 thermoelectric modules (TEMs) and a chaos-shaped brass heat exchanger is constructed. The temperature distribution of the TEG is analyzed based on an experimental setup, and the temperature uniformity optimization method is performed by chipping peak off and filling valley is taken to validate the improved output power. An automobile exhaust thermoelectric generator (AETEG) using four TEGs connected thermally in parallel and electrically in series is assembled into a prototype military SUV, its temperature distribution, output voltage, output power, system efficiency, inner resistance, and backpressure is analyzed, and several important influencing factors such as vehicle speed, clamping pressure, engine coolant flow rate, and ambient temperature on its output performance are tested. Experimental results demonstrate that higher vehicle speed, larger clamping pressure, faster engine coolant flow rate and lower ambient temperature can enhance the overall output performance, but the ambient temperature and coolant flow rate are less significant. The maximum output power of AETEG is 646.26 W, the corresponding conversion efficiency is 1.03%, and the increased backpressure changes from 1681 Pa to 1807 Pa when the highest vehicle speed is 125 km/h.

Perceptual mapping based on web search queries and consumer forum comments

Consumers’ online activities such as keyword searching and writing reviews can provide valuable information that reflects their perception of the market. This study proposes ways to analyze market structure and draw a perceptual map from the following two types of online data: keyword search and online consumer forum data. We apply our methodology to the imported car brands in South Korea automobile market. The multidimensional scaling (MDS) results provide different consumer insights depending on the nature of data. The inter-brand similarity values derived from the proposed two metrics are shown to be correlated. Especially, using consumer forum data, we apply our metric to analyzing the market structure of two sub-markets: midsize sedan and compact crossover sport utility vehicle (SUV). Furthermore, utilizing the proposed measures, we calculate the prototypicality of a brand and demonstrate its positive effect on sales. Marketing managers can apply our technique to understand the market structure and perform longitudinal studies to monitor consumers’ perceptual changes without conducting a time-consuming, traditional survey method.

Modeling and performance analysis of a vehicle with kinetic dynamic suspension system

This paper presents a kinetic dynamic suspension (KDS) system to achieve enhanced cooperative control of the roll and warp motion modes for on-road and off-road sports utility vehicles (SUV). The proposed KDS system consists of two hydraulic circuits acting on two pairs of torsional rods and levers, which can be treated as novel anti-roll bars. Hence, these anti-roll bars do not work independently, but are coupled to merely respond to particular motion modes. To verify the handling and ride performance of the system, a 14-DOF model of a SUV and a “magic formula” tire model are developed. The dynamic responses of the vehicle model with KDS suspension are obtained through half-sine bump, asynchronous sine road, and fishhook maneuver simulations. The responses of the KDS equipped vehicle are compared to those of one with anti-roll bars to demonstrate its improved performance and also illustrate the side-effects. The results show that the KDS system considerably improves the vehicle’s anti-roll ability. Furthermore, the vehicle’s warp stiffness is significantly reduced by the KDS system, which enhances the vertical load distribution of each wheel when driving off-road.

A Study of the Effect of the Front-End Styling of Sport Utility Vehicles on Pedestrian Head Injuries.

Background The number of sport utility vehicles (SUVs) on China market is continuously increasing. It is necessary to investigate the relationships between the front-end styling features of SUVs and head injuries at the styling design stage for improving the pedestrian protection performance and product development efficiency. Methods Styling feature parameters were extracted from the SUV side contour line. And simplified finite element models were established based on the 78 SUV side contour lines. Pedestrian headform impact simulations were performed and validated. The head injury criterion of 15 ms (HIC15) at four wrap-around distances was obtained. A multiple linear regression analysis method was employed to describe the relationships between the styling feature parameters and the HIC15 at each impact point. Results The relationship between the selected styling features and the HIC15 showed reasonable correlations, and the regression models and the selected independent variables showed statistical significance. Conclusions The regression equations obtained by multiple linear regression can be used to assess the performance of SUV styling in protecting pedestrians' heads and provide styling designers with technical guidance regarding their artistic creations.

A real-time non-linear vehicle preview model

Vehicle accident statistics indicate that fatalities due to rollover of sport utility vehicles (SUVs) are of international concern. Soft suspension, combined with high centre-of-gravity, increase SUV rollover propensity. Control strategies for prevention or mitigation of rollover, based on the current state of the vehicle, exist but most experience a delay in switching, due to response times of the controllers and actuators used to control vehicles dynamics. This paper proposes a real-time non-linear vehicle preview model (VPM) capable of accurately predicting future vehicle states based on current states. The preview model is developed and experimentally validated on a SUV. Results indicate that important vehicle states, including roll angle and lateral acceleration, can be accurately predicted up to more than 0.25 s into the future. Vehicle dynamics controllers can use the previewed states instead of the measured states to eliminate delays and make the strategies proactive instead of reactive.

Stress Relaxation of a Sport Utility Vehicle Chassis Using a Dynamic Force Counteracting Approach

Structural failures in a Chinese sport utility vehicle (SUV) Land-wind X6 chassis were reported in recent years, thus, it is meaningful to conduct trouble-shooting and effective optimization to improve the chassis. Stress relaxation of the Land-wind X6 chassis using a novel dynamic force counteracting approach was carried out in this study. Finite Element Analysis (FEA) model of the chassis was firstly established and theoretical modal analysis was performed using the FEA model, experimental modal analysis was followed to validate the theoretical modal analysis and the FEA model. Further static and local stress analyses demonstrate that irrational designs between the longitudinal beams and the suspension components lead to inadequate stiffness and excessive stress concentrations which would cause fatigue and structural failure when the SUV chassis is subject to complex and severe excitations. A novel dynamic forces counteracting approach was introduced to optimize the chassis structure, FEA results show that excessive stress concentrations were obviously eliminated and the chassis stiffness, especially the torsional stiffness was greatly improved after optimization, followed industrial implementation also verifies that the FEA-based study and product optimization performed in this work are successful and significant.