2,227 research outputs found
Steering heterogeneous sciences in the Dutch and Italian higher education systems
No full textThis paper studies how the implementation of New Public Management reforms in Higher Education affects the academic bodies’ steering in different national systems and disciplines. It is assumed that the steering capability depends on the characteristics of each system and discipline. The work includes three case studies (two Italian universities and one Dutch university); two research institutes are selected for each university: one HS institute (either Biomedical Sciences or Physics) and one SoSc institute (Management). Evidence confirms that steering capability improves in some disciplines, while other scientific fields remain hardly steerable because the levers are weak, the interest of society and policy makers in research outcomes is small, and the reputational organisations are very influential.Higher Education, Research, Funding, Evaluation, Steering, Governance, Social Sciences, Hard Sciences, New Public Management
Electric power steering: Recreating steering feel
No full textApplication of electronics in the automotive industry is extensively spreading. Electric power steering is hereby an exciting improvement to steering systems since the introduction of hydraulic power steering systems, which was first introduced as early as 1970s. Drivers desire hydraulic power steering behaviour because of its natural feel while providing assistance, but it has many disadvantages such as component lifecycle, oil leaks and power consumption. The use of electronic power steering provides the opportunity to remove such problems associated to hydraulic power steering and introduce benefits in terms of adaptability, comfort and safety. Since today's vehicles are making use of the by-wire technology for most components in the car, the additional electronic power steering will make it possible to have a full range of automated driving aids. Even though electric power steering comes with many advantages, there are still some disadvantages which are mentioned in numerous articles. These problems are mostly described as a lack in steering feel. More precisely it's described as if the front wheels are disconnected from the ground wheels. Many studies show different algorithms to minimise this, however it can be seen that even in the most successful products there is some complaint about this. An important tool to analyse this problem is the use of driving simulators. The implementation of a steering model that maintains high fidelity dynamics will bring many advantages. At the moment steering systems are developed by vehicle testing which is considered expensive and time consuming. The study of steering models will give more insight for the development in steering systems and the implementation in a HIL-simulator will ease the process of steering system development. This thesis will show the implementation of a steering model in a high fidelity steering simulator and it will propose a different method for solving the problem of steering feel loss. Finally it will conclude with driver in the loop experiments to show and evaluate the proposed method.Delft Center for Systems and ControlMechanical, Maritime and Materials Engineerin
Modelling and analysis of current and concept vehicles for the purpose of enhancing vehicle handling: executive summary
No full textIn this document, research into the modelling and analysis of current and concept vehicles for the purpose of enhancing vehicle handling is summarised. This work is recounted in detail in a portfolio of reports that has been submitted for the degree of Doctor of Engineering.
The portfolio includes fifteen submissions, eleven of which are concerned with the analysis and simulation of drivers' steering behaviour. Two relate to a novel suspension concept. One addresses a current problem caused by suspension variability and one introduces a process for selecting between new suspension concepts. Each of these fifteen submissions is summarised in this document. In addition, the order in which it is recommended that these submissions be read is listed.
In section 4, a project summary of the research into the analysis and simulation of drivers' steering behaviour is presented. Existing models of drivers' steering behaviour are reviewed. Vehicle tests that illustrate the different steering styles used by different drivers are recounted. A driver model that simulates the steering behaviour exhibited in these tests is formulated . Then, this driver model is used to develop a switching strategy for variable dampers. It is demonstrated that the switching strategy enhances vehicle handling and reduces the roll experienced by drivers during a handling manoeuvre.
Finally, it is verified that this research complies with the requirement of the degree of Doctor of Engineering to demonstrate innovation in the application of knowledge to the engineering business environment. This is achieved by specifying eight examples of where new ideas and methods have been applied to address current issues within the automotive industry
An approach to develop haptic feedback control reference for steering systems using open-loop driving manoeuvres
No full textIn this paper, a methodology to capture the model-based haptic feedback control reference for closed-loop steering systems is demonstrated. The parameterisation is based on the measurements of open-loop driving manoeuvres for the inertia-spring-damper-friction reference model. The steady-state and transient manoeuvres are used to identify the model parameters. The reference model is limited to the haptic feedback of driver excitation in the linear vehicle handling range and intended to be used in closed-loop steering control strategies. The model parameters have an intuitive interpretation that allows to be used in both admittance and impedance control setting. The feasibility of the proposed model is demonstrated in a validated simulation environment for electric power assisted steering and on a real hardware for the steer-by-wire force-feedback case.Intelligent Vehicle
Real-time Vehicle Steering Sensitivity Adaptation based on Time-Frequency Analysis of Individual Drivers' Steering Behaviour
No full textConventional steering systems in passenger vehicles have a mechanically fixed steering ratio. The steering sensitivity, defined as the amount of vehicle response to the driver's steering wheel input, remains fixed with changing road environments. Research has shown that driving comfort and safety can be improved when the vehicle's steering sensitivity is adapted to the road curvature profile. Current vehicle models can adapt the vehicle's steering sensitivity based on vehicle's speed and driver's steering wheel angle (i.e variable gear-ratio systems), or on individual selection of driving mode (i.e sport, comfort). It is hypothesised that adaptation of the steering sensitivity based on frequency measures of individual drivers' steering behaviour could improve driving comfort and safety. In a fixed-base driving simulator experiment involving 24 participants, real-time adaptation of steering wheel sensitivity based on individual drivers' steering behaviour was compared to three different fixed steering sensitivity settings on a road with changing road curvature. Here I show that intermittent switching frequency in drivers' steering movements can be used to adapt the vehicle's steering response to a varying road curvature. Significant differences in intermittent switching were found between different road curvature sections and between different steering sensitivity settings. Driver's positional control and comfort ratings did not significantly increase with the steering sensitivity adaptation strategy
Method of steering a vehicle
No full textVehicle and method of steering such a vehicle, wherein the vehicle has a steering wheel and steerable driving wheels and a transfer system for converting steering wheel actions to a steering angle of the steerable driving wheels, and wherein the transfer system is provided with a predefined stiffness value that determines said transfer system's transfer characteristic pertaining to a required amount of torque that is required in turning the steering wheel to effect a desired steering angle of the steerable driving wheels. In this vehicle and method of steering this vehicle, an area in front of the vehicle is monitored for detecting objects that the vehicle may hit when it continues its current path of movement. Depending on the detection of any such object the stiffness value of the transfer system is reduced so as to ease turning the steering wheel for effecting the desired steering angle of the steerable driving wheels.Biomechanical EngineeringMechanical, Maritime and Materials Engineerin
Influence of steering column friction on steering feel: A simulator study
No full textSteering feel is an important variable that contributes to drivers’ assessment of safety and comfort. As such, creating acceptable steering feel is one of the goals of automotive manufacturers. Prediction of subjective steering feel based on objective measures, for example, driver torque characteristics, can benefit the automotive industry by decreasing time and cost of the vehicle design process.This thesis project examined the effect of steering column friction, a sole objective parameter, on subjective steering feel and on the drivers’ performance. A driving simulator study was conducted with 17 non-professional drivers, who drove and assessed 11 dimensions of steering feel for five steering configurations. The experiment was carried out in a fixed base driving simulator. The steering configurations differed only in the level of column friction: 0 Nm, 0.15 Nm, 0.27 Nm, 0.39 Nm, 0.50 Nm. The driving task was divided into two sections: Drive on a highway without prescribed manoeuvres to evaluate the steering feel and lane following to collect objective measurements. Data collected during the experiment were tested with Friedman’s ANOVA. The results showed that the subjective assessments of the group were influenced by the level of friction. A more pronounced effect occurred between configurations with the lowest (0 Nm, 0.15 Nm) and the highest (0.50 Nm, 0.39 Nm) steering friction. Statistically significant differences were primarily found for the dimensions steering effort, steering effort in the neutral area, centering, and reluctant feel. Drivers assessed reluctant feel as increasing and returnability as decreasing with steering friction.In term’s of drivers’ performance, a higher workload was observed with an increase in steering friction, as measured by steering reversal rate. The same effect is present in another measure of workload, standard deviation of steering angle (STS; corrective movements become larger with friction). Lane keeping performance was not significantly affected by column friction in the present study.In summary, the results of the present study indicate that column friction is an important factor influencing a driver’s subjective steering feel, especially for configurations with at least 0.27 Nm. The findings suggest that friction can be tuned according to the driver’s preferences without incurring a decrease in performance. The potential effect of steering friction on drivers’ safety needs further study.Mechanical Engineering | Biomechanical Design - BioRobotic
Influence of Steering System Imperfections on Truck Steering Feel | a driving simulator study
No full textRoad safety is a prime concern in modern society. Statistics on traffic accidents show that articulated vehicles are overrepresented in fatal accidents. A third of all accidents happen during a vehicle maneuver with small lateral displacements: on-center handling. Stable guidance and handling behavior of the vehicle is mainly determined by its chassis, the vehicle dynamics and the steering system which needs to be reliable, predictable and to give the driver good steering feel. Defining steering feel is difficult because it is a subjective matter, but it is clear that good steering feel is necessary for safe vehicle control and an important element to driver experience. Next to the steering system mechanism and architecture the steering system parameters are important for truck driver steering feel. Mechanical systems will degrade over the life time of usage. Steering system imperfections are defined as the steering system parameters that change over lifetime. This study has been a first attempt to investigate the influence of the steering system imperfections on truck drivers steering feel during a simulation study. The first time used Mobile Truck Driving Simulator (MTDS) is validated by using earlier research, interviewing truck drivers, recording truck rides from the view of the driver, measuring dimensions, using employment guides and let professional drivers run test drives on the simulator. The study started with an explorative research on six steering system parameters that show a large degree of degradation: column bearing friction, bevel box friction, hydraulic cylinder friction, king pin friction, free play in the system and the tie rod stiffness. Professional truck drivers were asked to track the moment when the system does not show realistic steering feel anymore. During every test run one of the six steering system parameters is constantly changed using a predefined threshold tracking method resulting in general feedback and mean values of that particular parameter. The experiment resulted in three parameters which were varied in the main experiment: column friction, king pin friction and free play. The first objective of the main experiment was to find out how the three different steering system imperfections affect the steering feel of professional truck drivers. Steering feel is approached by a combination of four elements: general experience of handling, steering system, realism and steering system acceptance scale (SAS) based on the usefulness and satisfaction of the system. Professional truck drivers drove different test runs and completed a questionnaire. The increase of column friction, king pin friction and free play significantly influenced the evaluation of steering feel by the subjects. The second objective was to find out how the three steering system imperfections affect the objective driving indicators of professional truck drivers. Increasing the column friction results in an proportional increase of steering effort and driver burden. The increase of king pin friction to the first value results in an increase of steering effort, driver burden and steer jerk an increase of free play resulted in different steering reversal rate, an increase of steering business, steer rate, steer jerk and steering steadiness. This study shows the large impact of degradation of steering systems on driver experience and driver workload. No conclusion can be drawn on the driving performance regarding driving an articulated vehicle with a degraded steering system.Mechanical, Maritime and Materials EngineeringBiomechanical Engineerin
PBDAY. Steering Committee Meeting. Final Draft Reports. Report from the Siena Reference Centre.
No full textAuthor presents and discusses results from the Siena Reference Center ( PBDAY study) during the Steering Committee Meeting
Effect of steering model fidelity on subjective evaluation of truck steering feel
No full textThe steering behaviour in a driving simulator has a significant influence on a driving realism. This study investigates the influence of the complexity of a steering-system model on the subjective assessment of truck steering feel in on-centre handling. Ten subjects drove a highway task with and without lateral wind disturbance with 4 steering-system model variants. The results show that detailed modelling of the steering system plays a significant role in the subjective assessment of truck steering feel, and has a corresponding effect on objective steering performance.Biomechanical EngineeringMechanical, Maritime and Materials Engineerin
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