Safety in automobiles is gaining increasing importance. With the increasing trend of U.S. buyers towards SUVs, appropriate safety measures for SUVs need to be implemented. Since SUVs, as a vehicle type, have a higher center of gravity and hence have a greater tendency to rollover at high cornering speeds. The rollover can also occur due to the vertical road inputs like bumps and potholes which induce a rolling moment. The proposed rollover identification system would "couple" the two inputs from the suspension relative position sensors and the lateral acceleration sensor to predict rollover. The input to the suspension relative position sensors could be either due to the vehicle cornering, which results in the outer suspension getting compressed and the inner suspension getting extended, or maybe due to vertical road inputs. The principal objective is to differentiate the two types of inputs (since they can have opposing moment values) and further couple the same with the lateral acceleration input to form a rollover identification system. The work involves modeling of a semi-car model using the Dymola-vehicle dynamics simulation software. The semi-car model is developed to simulate values for the two proposed sensors. Then using NHTSA standard steering procedures and steering angle as the input, the lateral tire forces are generated. These tire forces serve as input to the Dymola model which is integrated into a Simulink model. The lateral acceleration and suspension relative position sensor values obtained are then used by LabVIEW to pass judgments on the type of rollover. The model was successfully developed in Dymola. The model with steering angle as input was able to generate values of lateral acceleration and lateral tire forces. The roll angle induced due to road inputs and vehicle cornering were estimated. Since the principal objective of modeling was to generate lateral acceleration values, these values were subsequently used in the LabVIEW Rollover Identification System where rollover induced either by maneuver or through road inputs were clearly identified.

<p>As more and more people conduct vigilance-based activities at times other than the traditional daytime work hours, the time utilization will continue to escalate in the next century and will further increase the risks of sleepiness-related accidents.</p><p>This project, which is commissioned by Scania CV AB, is to nvestigate the potential of a method for sleepiness detection belonging to esium AB. Our objective is to examine whether Scania CV AB should continue with the investigation of the patent method, and in that case, which patent parameters, that indicate sleepiness, should be more closely inquired. The purpose with the method of patent is to discover a sleepy driving behaviour. This method is based on the interaction that appears between the driver and the vehicle. The interaction consists of small spontaneous corrections with the steering wheel that in this report is called micro communication. How well the interaction is functioning can be measured in degree of interaction, which shows how well the driver and the truck interact with each other. The interaction between the driver and the vehicle is in this report looked upon as answers and questions with a certain reaction time, which appears with a certain answered question frequency. The differences in the signal’s amplitudes are measured in variation in amplitudes.</p><p>Experiments to collect relevant signals have to be conducted in order to investigate the potential with the method of the patent. It is eligible to collect data from a person falling asleep, which implies experiments conducted in a simulator. The experiments are executed in</p><p>a simulator, one test when they are alert and one when they are sleep deprived. Tests are also executed in a Scania truck. The purpose with these experiments is to collect data of the subject’s normal driving pattern in a truck and to investigate if it is possible to obtain</p><p>acceptable data in a truck.</p><p>The sleepiness experiments have indicated that the micro communication takes place in a frequency range of 0.25 to 6.0 Hz. The variables that have been found to detect sleepiness with high reliability are the reaction time and the degree of interaction presented in spectra.</p><p>The validation experiments have shown it is possible to collect exact and accurate data from the lateral acceleration and the steering wheel torque. But, there is more noise in the signals from truck then there is in the signals from the simulator.</p><p>This method for sleepiness detection has, according to the authors, a great potential. However, more experiments have to be conducted. The authors suggest further sleepiness experiments only conducted during night time. The subjects are sufficiently alert in the beginning of the test to receive data from normal driving behaviour. Physiological measurement could be interesting to have by the side of the subjective assessments as an additional base for comparison.</p>

<p>Accurate measurements from sensors measuring the vehicle's lateral behavior are vital in todays vehicle dynamic control systems such as the Electronic Stability Program (ESP). This thesis concerns accurate plausibilisation of two of these sensors, namely the yaw rate sensor and the lateral acceleration sensor. The estimation is based on Kalman filtering and culminates in the use of a 2 degree-of-freedom nonlinear two-track model describing the vehicle lateral dynamics. The unknown and time-varying cornering stiffnesses are adapted while the unknown yaw moment of inertia is estimated. The Kalman filter transforms the measured signals into a sequence of residuals that are then investigated with the aid of various change detection methods such as the CuSum algorithm. An investigation into the area of adaptive thresholding has also been made.</p><p>The change detection methods investigated successfully detects faults in both the yaw rate and the lateral acceleration sensor. It it also shown that adaptive thresholding can be used to improve the diagnosis system. All of the results have been evaluated on-line in a prototype vehicle with real-time fault injection.</p>

As more and more people conduct vigilance-based activities at times other than the traditional daytime work hours, the time utilization will continue to escalate in the next century and will further increase the risks of sleepiness-related accidents. This project, which is commissioned by Scania CV AB, is to nvestigate the potential of a method for sleepiness detection belonging to esium AB. Our objective is to examine whether Scania CV AB should continue with the investigation of the patent method, and in that case, which patent parameters, that indicate sleepiness, should be more closely inquired. The purpose with the method of patent is to discover a sleepy driving behaviour. This method is based on the interaction that appears between the driver and the vehicle. The interaction consists of small spontaneous corrections with the steering wheel that in this report is called micro communication. How well the interaction is functioning can be measured in degree of interaction, which shows how well the driver and the truck interact with each other. The interaction between the driver and the vehicle is in this report looked upon as answers and questions with a certain reaction time, which appears with a certain answered question frequency. The differences in the signal’s amplitudes are measured in variation in amplitudes. Experiments to collect relevant signals have to be conducted in order to investigate the potential with the method of the patent. It is eligible to collect data from a person falling asleep, which implies experiments conducted in a simulator. The experiments are executed in a simulator, one test when they are alert and one when they are sleep deprived. Tests are also executed in a Scania truck. The purpose with these experiments is to collect data of the subject’s normal driving pattern in a truck and to investigate if it is possible to obtain acceptable data in a truck. The sleepiness experiments have indicated that the micro communication takes place in a frequency range of 0.25 to 6.0 Hz. The variables that have been found to detect sleepiness with high reliability are the reaction time and the degree of interaction presented in spectra. The validation experiments have shown it is possible to collect exact and accurate data from the lateral acceleration and the steering wheel torque. But, there is more noise in the signals from truck then there is in the signals from the simulator. This method for sleepiness detection has, according to the authors, a great potential. However, more experiments have to be conducted. The authors suggest further sleepiness experiments only conducted during night time. The subjects are sufficiently alert in the beginning of the test to receive data from normal driving behaviour. Physiological measurement could be interesting to have by the side of the subjective assessments as an additional base for comparison.

Accurate measurements from sensors measuring the vehicle's lateral behavior are vital in todays vehicle dynamic control systems such as the Electronic Stability Program (ESP). This thesis concerns accurate plausibilisation of two of these sensors, namely the yaw rate sensor and the lateral acceleration sensor. The estimation is based on Kalman filtering and culminates in the use of a 2 degree-of-freedom nonlinear two-track model describing the vehicle lateral dynamics. The unknown and time-varying cornering stiffnesses are adapted while the unknown yaw moment of inertia is estimated. The Kalman filter transforms the measured signals into a sequence of residuals that are then investigated with the aid of various change detection methods such as the CuSum algorithm. An investigation into the area of adaptive thresholding has also been made. The change detection methods investigated successfully detects faults in both the yaw rate and the lateral acceleration sensor. It it also shown that adaptive thresholding can be used to improve the diagnosis system. All of the results have been evaluated on-line in a prototype vehicle with real-time fault injection.

Some of the results of an extensive track testing program at the Center for Vehicle Systems and Safety (CVeSS) at Virginia Tech for evaluating the roll stability of commercial trucks with 33-ft A-double trailers are evaluated. The study includes straight-rail trailers with heavy and light loading conditions. Commercial trucks are more susceptible to rollovers than passenger cars because of their higher center of gravity relative to their track width. Multi-trailer articulated heavy vehicles, such as A-doubles, are particularly prone to rollovers because of their articulation and rearward amplification. Electronic stability control (ESC) has been mandated by the National Highway Safety Administration (NHSTA) for Class 8 trucks and busses since 2017. When detecting oversteer or understeer, ESC automatically activates the brakes at the correct side of the steer and/or drive axle(s) to regain steering stability. ESC, however, often cannot sense the likelihood of trailer rollover in multi-trailer articulated heavy vehicles because of the articulation between the trailers and tractors. As a result of this, trailers are often equipped with roll stability control (RSC) systems to mitigate speed-induced rollovers. Sensing the trailer lateral acceleration, RSC activates the trailer brakes to reduce speed and lower the likelihood of rollover. However, a limited number of past studies have shown that the trailer roll angle may provide an earlier indication of a pending rollover than the lateral acceleration. This study intends to provide further analysis in this regard in an effort to improve the effectiveness of RSC systems for trailers. An extensive amount of data from track testing with a 33-ft A-double under heavy and light loading is evaluated. Particular attention is given to lateral accelerations and trailer roll angles prior to rollover and relative to RSC activation time. The study's results indicate that the trailer roll angle provides a slightly earlier indication of rollover than lateral acceleration during dynamic driving conditions, potentially resulting in a timelier activation of RSC. Of course, detecting the roll angle is often more challenging than lateral acceleration, which can be detected with an accelerometer. Additionally, the roll angle measurement may be subjected to errors and possibly unwanted RSC engagement. The study's results further indicate that the trailer-based RSC systems effectively mitigate rollovers in both quasi-steady-state and dynamic driving conditions. / Master of Science / Some of the results of an extensive track testing program at the Center for Vehicle Systems and Safety (CVeSS) at Virginia Tech for evaluating the roll stability of commercial trucks with 33-ft A-double trailers are evaluated. "33-ft A-doubles" commonly refer to a commercial truck that has a tractor with two trailers (in this case 33-ft in length) that are connected by an A-dolly. Their modularity and ease of connecting and disconnecting at various drop stations have made such commercial vehicles a common scene on U.S. highways due to the proliferation of e-commerce cargo. Compared to a single-unit or tractor semi-trailer combination, the double- or triple-trailer configurations offer several logistical benefits that make them more advantageous. The multi-trailer vehicles can carry more cargo per driver, lowering driver, fuel, and equipment costs significantly. There are, however, some challenges to operating multi-trailer articulated vehicles. On average, their accidents are more expensive than single-trailer or single-unit trucks. Additionally, they are more susceptible to rolling over and causing property damage, injuries, and at times fatalities. To reduce rollovers, systems with automated braking, called roll stability control (RSC), are often installed on the trailers. RSC applies the trailer brakes if it senses that the vehicle speed — the primary cause of most commercial vehicle accidents — exceeds the safe limit for negotiating a turn. In this study, we intend to evaluate the effectiveness of roll stability control (RSC) systems for reducing the likelihood of speed-induced rollovers. We will also explore ways of improving their performance. Namely, we will evaluate whether sensing the lateral acceleration of the trailer or its roll angle would provide a better means for timely activation of RSC. The study's results indicate that, although more challenging to measure, the trailer roll angle provides a slightly sooner indication of a pending rollover than lateral acceleration. The results also suggest that RSC systems vastly reduce the number of speed-induced rollovers in trucks with 33-ft A-double trailers under different trailer configurations and cargo weights.

Automotive vehicle manufacturers have been facing increased pressures from legislative bodies and consumers to reduce the fuel consumption and harmful emissions of their newly produced vehicles as a result of new research showing the detrimental effects these emissions have on the environment. These pressures are encouraging manufactures and researchers to invest billions of dollars into the development of new advanced vehicle technologies. Some of these investments have resulted in substantial progress in powertrain technologies that have led to the preliminary adoption of electrified powertrain vehicles. Other areas of research are actively working to reduce the energy consumption of a vehicle, regardless of its powertrain, by influencing driver behavior and by optimizing the way a vehicle travels between an origin and destination. This intelligent vehicle routing is done by analyzing a range of possible routes and selecting the route that consumes the least amount of fuel. An accurate method for predetermining vehicle energy expenditure along a given route before it is driven is needed to effectively implement intelligent vehicle routing systems. One common method is the generation of a road network-wide database with energy use figures for each section of road. This method requires expensive experimentation trials or network simulation software. Individual-level vehicle predictive energy estimation eliminates the need for costly fuel use generation by utilizing vehicle velocity generation techniques and vehicle powertrain models. Estimation of individual vehicle energy consumption along a route is done by identifying an origin-destination pair, detecting required full-stops along the path, and synthesizing multiple stop-to-stop velocity modes between each set of stops. The resulting velocity profile is paired with a specific vehicle powertrain model to determine fuel consumption. A drawback of this route generation technique is that the vehicle path is assumed to be one-dimensional and lacks inclusion of road curves and their associated velocity changes to maintain passenger comfort. This thesis evaluates the merit of discounting road curves in predictive vehicle energy consumption analyses and presents a technique for modeling common road corners that require velocity changes to limit passenger discomfort. The resulting corner synthesis method is combined with a validated vehicle powertrain model to complete full route consumption modeling. Two routes, an urban and highway, are modeled and driven to evaluate the accuracy of the full simulation model when compared with on-road data. The results show that corners can largely be ignored during energy consumption analysis for highways. The cornering effects on a vehicle during urban driving, however, should be included in urban route analyses with multiple road curves. Inclusion of the cornering effects during an example urban route analysis decreased the error between the on-road consumption data and the simulation results. / Master of Science

Un simulateur de conduite dynamique est un outil permettant, entre autres, d’étudier les processus d’intégration multi-sensorielle pour la perception du mouvement et la production du comportement de conduite. Néanmoins, les limitations mécaniques des simulateurs, qui imposent des stratégies dynamiques pour simuler le réel, peuvent avoir un impact défavorable sur la perception et le comportement du conducteur. Cette problématique est particulièrement vraie pour la prise de virages qui demeure une situation difficile à reproduire de façon réaliste notamment à cause des variations importantes d’accélérations latérales. Dans ce contexte, cette thèse présente des travaux de recherches permettant de mieux comprendre les processus d’intégration multi-sensorielle (rôle des informations inertielles et visuelles) pour la perception du mouvement en virages et de caractériser l’évolution d’un percept en fonction des conditions de simulation.En conclusion, il a été démontré que la perception des accélérations latérales est basée sur des processus non-linéaires. Le rôle des informations visuelles et inertielles semble donc dépendre des individus et du contexte (notamment du niveau des accélérations latérales) dans lequel ces stimulations sont produites. Sur la base de l’ensemble de ces résultats, des nouvelles pistes d’amélioration du simulateur dynamique SHERPA² de PSA sont proposées. Il est préconisé notamment d’employer un gain du mouvement latéral dégressif avec l’augmentation du niveau d’accélération latérale. / A dynamic driving simulator is a tool, among others, allowing the study of multisensory integration for motion perception and production of driving behavior. Nevertheless, the mechanical limitations of the simulators which impose dynamic strategies to simulate the real can have an adverse negative impact on the driver perception and its behavior. This issue is particularly true for cornering which remains a difficult situation to reproduce in a realistic way, because of massive lateral accelerations variations. In this context, this thesis presents research works allowing to understand the processes of multisensory integration (role of inertial and visual information) for the motion perception in cornering and to characterize the evolution of a percept as a function of simulation conditions.In conclusion, it has been demonstrated that the perception of lateral accelerations is based on non-linear processes. The roles of visual and inertial information seem to depend on the individuals and on the context (notably the level of lateral accelerations) in which these stimulations are produced. Base on of the overall results, new ways for improvement of the dynamic driving simulator SHERPA2 are proposed. It is notably preconized to employ a lateral motion gain digressive with the increase of lateral acceleration.

The main aim of this research project is to extend theories of four-wheel-steering as developed by J. Ackermann to include an individually steered four-wheel steering system for passenger vehicles. Ackermann’s theories, including theories available in this subject area, dwell much on vehicle system dynamics developed from what is called single track model and some call it a bicycle model. In the bicycle model, the front two wheels are bundled together. Similarly, the rear wheels are bundled together. The problem with this is that it assumes two front wheels or two rear wheels to be under the same road, vehicle and operating conditions. The reality on the ground and experiments that are conducted are to the contrary. Therefore this study discusses vehicle disturbance rejection through robust decoupling of yaw and lateral motions of the passenger vehicle. A mathematical model was developed and simulated using Matlab R2008b. The model was developed in such a way that conditions can be easily changed and simulated. The model responded well to variations in road and vehicle conditions. Focus was in the ability of the vehicle to reject external disturbances. To generate yaw moment during braking, the brake on the left front wheel was disconnected. This was done because lateral wind generators, as used by Ackermann, were not available. The results from both simulations and experiments show disturbance rejection in the steady state. Copyright / Dissertation (MSc)--University of Pretoria, 2010. / Mechanical and Aeronautical Engineering / unrestricted

Today, Sport Utility Vehicles are marketed as both on-road and off-road vehicles. This results in a compromise when designing the suspension of the vehicle. If the suspension characteristics are fixed, the vehicle cannot have good handling capabilities on highways and good ride comfort over rough terrain. The rollover propensity of this type of vehicle compared to normal cars is high because it has a combination of a high centre of gravity and a softer suspension. The 4 State Semi-active Suspension System (4S4) that can switch between two discrete spring characteristics as well as two discrete damper characteristics, has been proven to overcome this compromise. The soft suspension setting (soft spring and low damping) is used for ride comfort, while the hard suspension setting (stiff spring and high damping) is used for handling. The following question arises: when is which setting most appropriate? The two main contributing factors are the terrain profile and the driver’s actions. Ride comfort is primarily dependant on the terrain that the vehicle is travelling over. If the terrain can be identified, certain driving styles can be expected for that specific environment. The terrains range from rough and uncomfortable to smooth with high speed manoeuvring. Terrain classification methods are proposed and tested with measured data from the test vehicle on known terrain types. Good results were obtained from the terrain classification methods. Five terrain types were accurately identified from over an hour’s worth of vehicle testing. Handling manoeuvres happen unexpectedly, often to avoid an accident. To improve the handling and therefore safety of the vehicle, the 4S4 can be switched to the hard suspension setting, which results in a reduced body roll angle. This decision should be made quickly with the occupants’ safety as the priority. Methods were investigated that will determine when to switch the suspension to the handling mode based on the kinematics of the vehicle. The switching strategies proposed in this study have the potential, with a little refinement, to make the ride versus handling decision correctly. Copyright 2007, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. Please cite as follows: Bester, R 2007, The ride comfort versus handling decision for off-road vehicles, MEng dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-10252007-111611 / > / Dissertation (MEng (Mechanical Engineering))--University of Pretoria, 2007. / Mechanical and Aeronautical Engineering / unrestricted