Stability Control of Triple Trailer Vehicles

While vehicle stability control is a well-established technology in the passenger car realm, it is still an area of active research for commercial vehicles as indicated by the recent notice of proposed rulemaking on commercial vehicle stability by the National Highway Traffic Safety Administration (NHTSA, 2012). The reasons that commercial vehicle electronic stability control (ESC) development has lagged passenger vehicle ESC include the fact that the industry is generally slow to adopt new technologies and that commercial vehicles are far more complex requiring adaptation of existing technology. From the controller theory perspective, current commercial vehicle stability systems are generally passenger car based ESC systems that have been modified to manage additional brakes (axles). They do not monitor the entire vehicle nor do they manage the entire vehicle as a system

Pneumatic Tire

For many years, tire engineers relied on the monograph, \u27Mechanics of Pneumatic Tires\u27, for detailed information about the principles of tire design and use. Published originally by the National Bureau of Standards, U.S. Department of Commerce, in 1971, and a later (1981) edition by the National Highway Traffic Safety Administration (NHTSA), U.S. Department of Transportation, it has long been out of print. No textbook or monograph of comparable range and depth has appeared since. While many chapters of the two editions contain authoritative reviews that are still relevant today, they were prepared in an era when bias ply and belted-bias tires were in widespread use in the United States and thus did not deal in a comprehensive way with more recent tire technology, notably the radial constructions now adopted nearly universally. In 2002, it was preposed that NHTSA should sponsor and publish electronically a new book on passenger tires, under editorship of the University of Akron, to meet the needs of a new generation of tire scientists, engineers, designers, and users. This text is the outcome. The chapter authors are recognized authorities in tire science and technology. They have prepared scholarly and up-to-date reviews of the various aspects of passenger car tire design, construction and use, and included test questions in many instances, so that the book can be used for self-study or as a teaching text by engineers and others entering the tire industry

Advances in Mechanical Systems Dynamics 2020

The fundamentals of mechanical system dynamics were established before the beginning of the industrial era. The 18th century was a very important time for science and was characterized by the development of classical mechanics. This development progressed in the 19th century, and new, important applications related to industrialization were found and studied. The development of computers in the 20th century revolutionized mechanical system dynamics owing to the development of numerical simulation. We are now in the presence of the fourth industrial revolution. Mechanical systems are increasingly integrated with electrical, fluidic, and electronic systems, and the industrial environment has become characterized by the cyber-physical systems of industry 4.0. Within this framework, the status-of-the-art has become represented by integrated mechanical systems and supported by accurate dynamic models able to predict their dynamic behavior. Therefore, mechanical systems dynamics will play a central role in forthcoming years. This Special Issue aims to disseminate the latest research findings and ideas in the field of mechanical systems dynamics, with particular emphasis on novel trends and applications

Sensor Fault Detection and Fault-Tolerant Estimation of Vehicle States

Manufacturing smarter and more reliable vehicles is a progressing trend in the automotive industry. Many of today’s vehicles are equipped with driver assistant, automated driving and advanced stability control systems. These systems rely on measured or estimated information to accomplish their tasks. Evidently, reliability of the sensory measurements and the estimate information is essential for desirable operation of advanced vehicle subsystems. This thesis proposes a novel methodology to detect vehicle sensor faults, reconstruct the faulty sensory signals and deliver fault-tolerant estimation of vehicle states. The proposed method can detect failures of the longitudinal, lateral and vertical acceleration sensors, roll rate, yaw rate and pitch rate sensors, steering angle sensor, suspension height sensors, and motor torque sensors. The proposed structure can deliver fault-tolerant estimations of the vehicle states including the longitudinal, lateral and vertical tire forces, longitudinal and lateral velocities, roll angle, and pitch angle. Road grade and bank angles are also estimated in this method even in presence of sensor faults. The unified structure in this thesis is realized by fusion of analytical redundancy relations, fault detection observers and adaptive state estimation algorithms. The proposed method can isolate the faults for vehicle stability and control systems and deliver accurate estimation of vehicle states required by such systems despite sensor failures. The methods developed in this thesis are validated through experiments and can operate reliably in various driving scenarios

Advanced Control and Estimation Concepts, and New Hardware Topologies for Future Mobility

According to the National Research Council, the use of embedded systems throughout society could well overtake previous milestones in the information revolution. Mechatronics is the synergistic combination of electronic, mechanical engineering, controls, software and systems engineering in the design of processes and products. Mechatronic systems put “intelligence” into physical systems. Embedded sensors/actuators/processors are integral parts of mechatronic systems. The implementation of mechatronic systems is consistently on the rise. However, manufacturers are working hard to reduce the implementation cost of these systems while trying avoid compromising product quality. One way of addressing these conflicting objectives is through new automatic control methods, virtual sensing/estimation, and new innovative hardware topologies

Autonomous Control and Automotive Simulator Based Driver Training Methodologies for Vehicle Run-Off-Road and Recovery Events

Traffic fatalities and injuries continue to demand the attention of researchers and governments across the world as they remain significant factors in public health and safety. Enhanced legislature along with vehicle and roadway technology has helped to reduce the impact of traffic crashes in many scenarios. However, one specifically troublesome area of traffic safety, which persists, is run-off-road (ROR) where a vehicle\u27s wheels leave the paved portion of the roadway and begin traveling on the shoulder or side of the road. Large percentages of fatal and injury traffic crashes are attributable to ROR. One of the most critical reasons why ROR scenarios quickly evolve into serious crashes is poor driver performance. Drivers are unprepared to safely handle the situation and often execute dangerous maneuvers, such as overcorrection or sudden braking, which can lead to devastating results. Currently implemented ROR countermeasures such as roadway infrastructure modifications and vehicle safety systems have helped to mitigate some ROR events but remain limited in their approach. A complete solution must directly address the primary factor contributing to ROR crashes which is driver performance errors. Four vehicle safety control systems, based on sliding control, linear quadratic, state flow, and classical theories, were developed to autonomously recover a vehicle from ROR without driver intervention. The vehicle response was simulated for each controller under a variety of common road departure and return scenarios. The results showed that the linear quadratic and sliding control methodologies outperformed the other controllers in terms of overall stability. However, the linear quadratic controller was the only design to safely recover the vehicle in all of the simulation conditions examined. On average, it performed the recovery almost 50 percent faster and with 40 percent less lateral error than the sliding controller at the expense of higher yaw rates. The performance of the linear quadratic and sliding algorithms was investigated further to include more complex vehicle modeling, state estimation techniques, and sensor measurement noise. The two controllers were simulated amongst a variety of ROR conditions where typical driver performance was inadequate to safely operate the vehicle. The sliding controller recovered the fastest within the nominal conditions but exhibited large variability in performance amongst the more extreme ROR scenarios. Despite some small sacrifice in lateral error and yaw rate, the linear quadratic controller demonstrated a higher level of consistency and stability amongst the various conditions examined. Overall, the linear quadratic controller recovered the vehicle 25 percent faster than the sliding controller while using 70 percent less steering, which combined with its robust performance, indicates its high potential as an autonomous ROR countermeasure. The present status of autonomous vehicle control research for ROR remains premature for commercial implementation; in the meantime, another countermeasure which directly addresses driver performance is driver education and training. An automotive simulator based ROR training program was developed to instruct drivers on how to perform a safe and effective recovery from ROR. A pilot study, involving seventeen human subject participants, was conducted to evaluate the effectiveness of the training program and whether the participants\u27 ROR recovery skills increased following the training. Based on specific evaluation criteria and a developed scoring system, it was shown that drivers did learn from the training program and were able to better utilize proper recovery methods. The pilot study also revealed that drivers improved their recovery scores by an average of 78 percent. Building on the success observed in the pilot study, a second human subject study was used to validate the simulator as an effective tool for replicating the ROR experience with the additional benefit of receiving insight into driver reactions to ROR. Analysis of variance results of subjective questionnaire data and objective performance evaluation parameters showed strong correlations to ROR crash data and previous ROR study conclusions. In particular, higher vehicle velocities, curved roads, and higher friction coefficient differences between the road and shoulder all negatively impacted drivers\u27 recoveries from ROR. The only non-significant impact found was that of the roadway edge, indicating a possible limitation of the simulator system with respect to that particular environment variable. The validation study provides a foundation for further evaluation and development of a simulator based ROR recovery training program to help equip drivers with the skills to safely recognize and recover from this dangerous and often deadly scenario. Finally, building on the findings of the pilot study and validation study, a total of 75 individuals participated in a pre-post experiment to examine the effect of a training video on improving driver performance during a set of simulated ROR scenarios (e.g., on a high speed highway, a horizontal curve, and a residential rural road). In each scenario, the vehicle was unexpectedly forced into an ROR scenario for which the drivers were instructed to recover as safely as possible. The treatment group then watched a custom ROR training video while the control group viewed a placebo video. The participants then drove the same simulated ROR scenarios. The results suggest that the training video had a significant positive effect on drivers\u27 steering response on all three roadway conditions as well as improvements in vehicle stability, subjectively rated demand on the driver, and self-evaluated performance in the highway scenario. Under the highway conditions, 84 percent of the treatment group and 52 percent of the control group recovered from the ROR events. In total, the treatment group recovered from the ROR events 58 percent of the time while the control group recovered 45 percent of the time. The results of this study suggest that even a short video about recovering from ROR events can significantly influence a driver\u27s ability to recover. It is possible that additional training may have further benefits in recovering from ROR events

Investigations on the Roll Stability of a Semitrailer Vehicle Subjected to Gusty Crosswind Aerodynamic Forces

Threats of high crosswind gusts on running safety of modern road and rail vehicles have been reported around the world. Under high transient crosswind conditions, sudden changes in vehicle aerodynamic forces can lead to adverse effects on vehicle dynamics and stability. Moreover, due to increase in maximum speed limits and body dimensions of commercial vehicles as well as reduction in their weights, large class vehicles, in particular, are more prone to rollover accidents in strong crosswind situations, especially at cruising speeds or at exposed sites. Such crosswind accidents have been observed even at low vehicle speed of 15 m/s in adverse windy weather. It is therefore essential to conduct detailed investigations on the aerodynamic performance of commercial vehicles under crosswind conditions in order to improve their crosswind stability. In this study, estimation of unsteady aerodynamic forces acting on a high-sided tractor-trailer vehicle have been carried out based on experiential and numerical simulations. Although natural crosswind gusts are high-turbulent phenomena, and have a large variability in types and origins, this study suggests employing two gust scenarios based on two different methods: 1. Transient wind gust scenario developed in wind-tunnel to represents a high-sided tractor semitrailer vehicle moving on a road in moderate wind condition and immediately being hit by wind gust. 2. Deterministic crosswind scenario with gusts in exponential shapes has been considered to predict crosswind aerodynamic forces of a high-sided tractor semitrailer vehicle moving through wind exposed area. This scenario is specified in the Technical Specification for Interoperability (TSI) standard, but it has been employed in this study in combination with Computational Fluid Dynamics (CFD). A series of time-dependent crosswind aerodynamic forces acting on the tractor-semitrailer vehicle have been predicted. Moreover, to illustrate the potential influence of crosswind gusts on a high-sided tractor semitrailer vehicle, instantaneous gust flow structures for proposed wind scenarios and wind pressure fields were presented. The results show that both wind gust scenarios have significant unsteady effects on the side aerodynamic force and the roll moment of the vehicle. Furthermore, there are significant variations in aerodynamic loads, and the flow field becomes more complicated, consistent with the gust’s strength. These conclusions strongly suggested the importance of considering the unsteady aerodynamic forces in the analysis of heavy vehicle roll dynamics. Lateral load transfer ratio (LTR) is a criterion that is often used for designing ground vehicle rollover warning technologies to indicate the vehicles rollover status. Generally, LTR index depends on road geometry and vehicle dynamic characteristics. However, as mentioned above, crosswind loads have the potential to influence the roll stability and therefore the safety of large commercial vehicles. Therefore, this thesis presents the research carried out to improve the traditional LTR for a high-sided tractor semitrailer vehicle to be more efficient in crosswind environment. For this purpose, since experimental investigations on vehicle rollover dynamics are difficult to carry out, a coupled simulation of crosswind aerodynamic forces and multi-body vehicle dynamics has been proposed. In this method, the predicted aerodynamic forces result due to the proposed wind scenarios were input into multi-body dynamic simulations of the tractor semi-trailer vehicle that were performed through Adams/Car software. Based on this coupled analysis, dynamic responses of the vehicle to fluctuating crosswind conditions have been predicted. Moreover, all parameters of the LTR index such as body roll angle and lateral acceleration were estimated through a critical turning manoeuvre with crosswind actions. The investigation results show that, in the same manoeuvre, in comparison with the traditional LTR index (i.e., in which crosswind aerodynamic forces are ignored), the improved LTR rollover (crosswind) indicator, has successfully detected wheel lift–up conditions when crosswind aerodynamic loads are considered. Also, average values of the LTR measured under crosswind effects are about 22% higher than those of corresponding traditional LTR index. Therefore, the rollover indicator that has been improved by the proposed methodology can provide more reliable information to the warning or control system in the presence of wind conditions

Enhancement of Ride and Directional Performances of Articulated Vehicles via Optimal Frame Steering and Hydro-Pneumatic Suspension

Off-road vehicles employed in agriculture, construction, forestry and mining sectors are known to exhibit comprehensive levels of terrain-induced ride vibration and relatively lower directional stability limits, especially for the articulated frame-steered vehicles (AFSV). The transmitted whole-body vibration (WBV) exposure levels to the human operators generally exceed the safety limits defined in ISO-2631-1 and the European Community guidelines. Moreover, the directional stability limits are generally assessed neglecting the contributions due to terrain roughness and kineto-dynamics of the articulated frame steering (AFS) system. Increasing demand for high load capacity and high-speed off-road vehicles raises greater concerns for both the directional stability limits and WBV exposure. The criterion for acceptable handling and stability limits of such vehicles do not yet exist and need to be established. Furthermore, both directional stability performance and ride vibration characteristics are coupled and pose conflicting vehicle suspension design requirements. This dissertation research focuses on enhancement of ride, and roll- and yaw-plane stability performance measures of frame-steered vehicle via analysis of kineto-dynamics of the AFS system and hydro-pneumatic suspensions. A roll stability performance measure is initially proposed for off-road vehicles considering magnitude and spectral contents of the terrain elevations. The roll dynamics of an off-road vehicle operating on random rough terrains were investigated, where the two terrain-track profiles were synthesized considering coherency between them. It is shown that a measure based on steady-turning root-mean-square lateral acceleration corresponding to the sustained period of unity lateral-load-transfer-ratio prior to the absolute-rollover, could serve as a reliable measure of roll stability of vehicles operating on random rough terrains. The simulation results revealed adverse effects of terrain elevation magnitude on the roll stability, while a relatively higher coherency resulted in lower terrain roll-excitation and thereby higher roll stability. The yaw-plane stability limits of an AFSV are investigated in terms of free yaw-oscillations as well as transient steering characteristics through field measurements and simulations of kineto-dynamics of the AFS system. It was shown that employing hydraulic fluid with higher bulk modulus and increasing the steering arm lengths would yield higher yaw stiffness of the AFS system and thereby higher frequency of yaw-oscillations. Greater leakage flows and viscous seal friction within the AFS system struts caused higher yaw damping coefficient but worsened the steering gain and articulation rate. A design guidance of the AFS system is subsequently proposed. The essential objective measures are further identified considering the AFSV’s yaw oscillation/stability and steering performances, so as to seek an optimal design of the AFS system. For enhancing the ride performance of AFSV, a simple and low cost design of a hydro-pneumatic suspension (HPS) is proposed. The nonlinear stiffness and damping properties of the HPS strut that permits entrapment of gas into the hydraulic oil were characterized experimentally and analytically. The formation of the gas-oil emulsion was studied in the laboratory, and variations in the bulk modulus and mass density of the emulsion were formulated as a function of the gas volume fraction. The model results obtained under different excitations in the 0.1 to 8 Hz frequency range showed reasonably good agreements with the measured stiffness and damping properties of the HPS strut. The results showed that increasing the fluid compressibility causes increase in effective stiffness but considerable reduction in the damping in a highly nonlinear manner. Increasing the gas volume fraction resulted in substantial hysteresis in the force-deflection and force-velocity characteristics of the strut. A three-dimensional AFSV model is subsequently formulated integrating the hydro-mechanical AFS system and a hydro-pneumatic suspension. The HPS is implemented only at the front axle, which supports the driver cabin in order to preserve the roll stability of the vehicle. The validity of the model is illustrated through field measurements on a prototype vehicle. The suspension parameters are selected through design sensitivity analyses and optimization, considering integrated ride vibration, and roll- and yaw-plane stability performance measures. The results suggested that implementation of HPS to the front unit alone could help preserve the directional stability limits compared to the unsuspended prototype vehicle and reduce the ride vibration exposure by nearly 30%. The results of sensitivity analyses revealed that the directional stability performance limits are only slightly affected by the HPS parameters. Further reduction in the ride vibration exposure was attained with the optimal design, irrespective of the payload variations

Performance and Safety Enhancement Strategies in Vehicle Dynamics and Ground Contact

Recent trends in vehicle engineering are testament to the great efforts that scientists and industries have made to seek solutions to enhance both the performance and safety of vehicular systems. This Special Issue aims to contribute to the study of modern vehicle dynamics, attracting recent experimental and in-simulation advances that are the basis for current technological growth and future mobility. The area involves research, studies, and projects derived from vehicle dynamics that aim to enhance vehicle performance in terms of handling, comfort, and adherence, and to examine safety optimization in the emerging contexts of smart, connected, and autonomous driving.This Special Issue focuses on new findings in the following topics:(1) Experimental and modelling activities that aim to investigate interaction phenomena from the macroscale, analyzing vehicle data, to the microscale, accounting for local contact mechanics; (2) Control strategies focused on vehicle performance enhancement, in terms of handling/grip, comfort and safety for passengers, motorsports, and future mobility scenarios; (3) Innovative technologies to improve the safety and performance of the vehicle and its subsystems; (4) Identification of vehicle and tire/wheel model parameters and status with innovative methodologies and algorithms; (5) Implementation of real-time software, logics, and models in onboard architectures and driving simulators; (6) Studies and analyses oriented toward the correlation among the factors affecting vehicle performance and safety; (7) Application use cases in road and off-road vehicles, e-bikes, motorcycles, buses, trucks, etc

Advances in Intelligent Vehicle Control

This book is a printed edition of the Special Issue Advances in Intelligent Vehicle Control that was published in the journal Sensors. It presents a collection of eleven papers that covers a range of topics, such as the development of intelligent control algorithms for active safety systems, smart sensors, and intelligent and efficient driving. The contributions presented in these papers can serve as useful tools for researchers who are interested in new vehicle technology and in the improvement of vehicle control systems