1,721,338 research outputs found
Proceedings of the 4th International Tyre Colloquium: Tyre Models for Vehicle Dynamics Analysis: 20-21 April 2015, University of Surrey, Guildford, United Kingdom
No full textThe International Tyre Colloquium has a successful history in discussing the latest progress in the understanding and simulation of tyre-road-vehicle interactions. The first Tyre Colloquium was organised by Prof Pacejka in 1991 (Delft), the second one was in Berlin in 1997, organised by Prof Böhm and Prof Willumeit, and the third one was in Vienna in 2004, organised by Prof Lugner and Prof Plöchl. In line with the tradition, the 4th Tyre Colloquium was focused on topics related to modelling of tyres for vehicle dynamics analysis including: • Tyre measurements and measurement techniques • Tyre models • Application of tyre models to vehicle dynamics • Determination of tyre model parameters • Measurement and modelling of rubber friction • Tyre-road contact • Evaluation and verification of tyre models • Tyre design features and their consequences for the tyre behaviou
Proceedings of the 4th International Tyre Colloquium: Tyre Models for Vehicle Dynamics Analysis: 20-21 April 2015, University of Surrey, Guildford, United Kingdom
Full text linkThe International Tyre Colloquium has a successful history in discussing the latest progress in the understanding and simulation of tyre-road-vehicle interactions. The first Tyre Colloquium was organised by Prof Pacejka in 1991 (Delft), the second one was in Berlin in 1997, organised by Prof Böhm and Prof Willumeit, and the third one was in Vienna in 2004, organised by Prof Lugner and Prof Plöchl. In line with the tradition, the 4th Tyre Colloquium was focused on topics related to modelling of tyres for vehicle dynamics analysis including: • Tyre measurements and measurement techniques • Tyre models • Application of tyre models to vehicle dynamics • Determination of tyre model parameters • Measurement and modelling of rubber friction • Tyre-road contact • Evaluation and verification of tyre models • Tyre design features and their consequences for the tyre behaviou
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
A novel robust optimal active control of vehicle suspension systems
Full text link© IFAC.Using Lyapunov theory, Pontryagin's minimum principle, and affine quadratic stability, a novel robust optimal control strategy is developed for active suspension systems to enhance vehicle ride comfort and handling performance. The controller has a simple structure, making its suitable for real-time implementation. The required sensor configuration includes a six-axis IMU and four LVDTs. The proposed controller is suitable for on-road commercial vehicles where ride comfort over bump disturbances and handling performance are the most concerns. The effectiveness of the controller is verified through simulation results using IPG CarMaker software
Optimal Wheel Torque Distribution for a Four-Wheel-Drive Fully Electric Vehicle
No full textVehicle handling in steady-state and transient conditions can be significantly enhanced with the continuous modulation of the driving and braking torques of each wheel via dedicated torque-vectoring controllers. For fully electric vehicles with multiple electric motor drives, the enhancements can be achieved through a control allocation algorithm for the determination of the wheel torque distribution. This article analyzes alternative cost functions developed for the allocation of the wheel torques for a four-wheel-driven fully electric vehicle with individually controlled motors. Results in terms of wheel torque and tire slip distributions among the four wheels, and of input power to the electric drivetrains as functions of lateral acceleration are presented and discussed in detail. The cost functions based on minimizing tire slip allow better control performance than the functions based on energy efficiency for the case-study vehicle
Design and comparison of the handling performance of different electric vehicle layouts
No full textIn contrast with conventional vehicles driven by an internal-combustion engine, the number of motors in fully electric cars is not fixed. A variety of architectural solutions, including from one to four individually controlled electric drive units, is possible and opens up new avenues in the design of vehicle characteristics. In particular, individual control of multiple electric powertrains promises to enhance the handling performance in steady-state and dynamic conditions. For the analysis and selection of the best electric powertrain layout based on the expected vehicle characteristics and performance, new analytical tools and metrics are required. This article presents and demonstrates a novel offline procedure for the design of the feedforward control action of the vehicle dynamics controller of a fully electric vehicle and three performance indicators for the objective comparison of the handling potential of alternative electric powertrain layouts. The results demonstrate that the proposed offline routine allows the desired understeer characteristics to be achieved with any of the investigated vehicle configurations, in traction and braking conditions. With respect to linear handling characteristics, the simulations indicate that the influence of torque-vectoring is independent of the location of the controlled axles (front or rear) and is considerably affected by the number of controlled axles. © IMechE 2013
Wheel torque distribution criteria for electric vehicles with torque-vectoring differentials
No full textThe continuous and precise modulation of the driving and braking torques of each wheel is considered the ultimate goal for controlling the performance of a vehicle in steady-state and transient conditions. To do so, dedicated torque-vectoring (TV) controllers that allow optimal wheel torque distribution under all possible driving conditions have to be developed. Commonly, vehicle TV controllers are based on a hierarchical approach, consisting of a high-level supervisory controller that evaluates a corrective yaw moment and a low-level controller that defines the individual wheel torque reference values. The problem of the optimal individual wheel torque distribution for a particular driving condition can be solved through an optimization-based control-allocation (CA) algorithm, which must rely on the appropriate selection of the objective function. With a newly developed offline optimization procedure, this paper assesses the performance of alternative objective functions for the optimal wheel torque distribution of a four-wheel-drive (4WD) fully electric vehicle. Results show that objective functions based on the minimum tire slip criterion provide better control performance than functions based on energy efficiency. © 2013 IEEE
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Driving modes for designing the cornering response of fully electric vehicles with multiple motors
No full textAbstract Fully electric vehicles with multiple drivetrains allow a significant variation of the steady-state and transient cornering responses through the individual control of the electric motor drives. As a consequence, alternative driving modes can be created that provide the driver the option to select the preferred dynamic vehicle behavior. This article presents a torque-vectoring control structure based on the combination of feedforward and feedback contributions for the continuous control of vehicle yaw rate. The controller is specifically developed to be easily implementable on real-world vehicles. A novel model-based procedure for the definition of the control objectives is described in detail, together with the automated tuning process of the algorithm. The implemented control functions are demonstrated with experimental vehicle tests. The results show the possibilities of torque-vectoring control in designing the vehicle understeer characteristic
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