The Experts below are selected from a list of 10326 Experts worldwide ranked by ideXlab platform
J. Karl Hedrick - One of the best experts on this subject based on the ideXlab platform.
-
ACC - Roll prediction-based optimal control for safe path following
2015 American Control Conference (ACC), 2015Co-Authors: Sanghyun Hong, J. Karl HedrickAbstract:Autonomous vehicles can risk dangerous rollover if they corner without taking roll motion into consideration. This paper proposes a control algorithm to follow a curved road while simultaneously preventing rollover. Model predictive control is applied to minimize roll motion throughout cornering. The prediction of vehicle state is based on a four-wheel nonlinear vehicle Model with roll dynamics and a tire Brush Model. Full braking is utilized as a control actuator to achieve an optimal balance in the trade-off between vehicle speed and roll motion. CarSim simulations show the performance of the proposed control approach and the influence of vehicle parameters on control performance.
-
Intelligent Vehicles Symposium - Tire-road friction coefficient estimation with vehicle steering
2013 IEEE Intelligent Vehicles Symposium (IV), 2013Co-Authors: Sanghyun Hong, J. Karl HedrickAbstract:Lateral tire deflection enables the estimation of the tire-road friction coefficient. Vehicle steering, such as driving on a curved highway, can influence the friction coefficient estimation. This paper demonstrates an algorithm to estimate the tire-road friction coefficient when a vehicle is steering. The relationship between the friction coefficient and the vehicle steering is derived through a tire Brush Model. The change of lateral velocity inside the tire-road contact patch is used in the algorithm along with the lateral deflection. The Models for the lateral deflection and the change of lateral velocity are derived with the tire Brush Model, a simple tire Model, and a parabolic lateral deflection Model. Approximated tire slip angles are fed to the estimation algorithm to capture the change of the steering angle. This algorithm is evaluated in experiments with the steering of a test vehicle.
Sanghyun Hong - One of the best experts on this subject based on the ideXlab platform.
-
ACC - Roll prediction-based optimal control for safe path following
2015 American Control Conference (ACC), 2015Co-Authors: Sanghyun Hong, J. Karl HedrickAbstract:Autonomous vehicles can risk dangerous rollover if they corner without taking roll motion into consideration. This paper proposes a control algorithm to follow a curved road while simultaneously preventing rollover. Model predictive control is applied to minimize roll motion throughout cornering. The prediction of vehicle state is based on a four-wheel nonlinear vehicle Model with roll dynamics and a tire Brush Model. Full braking is utilized as a control actuator to achieve an optimal balance in the trade-off between vehicle speed and roll motion. CarSim simulations show the performance of the proposed control approach and the influence of vehicle parameters on control performance.
-
Tyre-road friction coefficient estimation based on tyre sensors and lateral tyre deflection: Modelling, simulations and experiments
Vehicle System Dynamics, 2013Co-Authors: Sanghyun Hong, Gurkan Erdogan, Karl Hedrick, Francesco BorrelliAbstract:The estimation of the tyre–road friction coefficient is fundamental for vehicle control systems. Tyre sensors enable the friction coefficient estimation based on signals extracted directly from tyres. This paper presents a tyre–road friction coefficient estimation algorithm based on tyre lateral deflection obtained from lateral acceleration. The lateral acceleration is measured by wireless three-dimensional accelerometers embedded inside the tyres. The proposed algorithm first determines the contact patch using a radial acceleration profile. Then, the portion of the lateral acceleration profile, only inside the tyre–road contact patch, is used to estimate the friction coefficient through a tyre Brush Model and a simple tyre Model. The proposed strategy accounts for orientation-variation of accelerometer body frame during tyre rotation. The effectiveness and performance of the algorithm are demonstrated through finite element Model simulations and experimental tests with small tyre slip angles on different...
-
Intelligent Vehicles Symposium - Tire-road friction coefficient estimation with vehicle steering
2013 IEEE Intelligent Vehicles Symposium (IV), 2013Co-Authors: Sanghyun Hong, J. Karl HedrickAbstract:Lateral tire deflection enables the estimation of the tire-road friction coefficient. Vehicle steering, such as driving on a curved highway, can influence the friction coefficient estimation. This paper demonstrates an algorithm to estimate the tire-road friction coefficient when a vehicle is steering. The relationship between the friction coefficient and the vehicle steering is derived through a tire Brush Model. The change of lateral velocity inside the tire-road contact patch is used in the algorithm along with the lateral deflection. The Models for the lateral deflection and the change of lateral velocity are derived with the tire Brush Model, a simple tire Model, and a parabolic lateral deflection Model. Approximated tire slip angles are fed to the estimation algorithm to capture the change of the steering angle. This algorithm is evaluated in experiments with the steering of a test vehicle.
Yanning Zhang - One of the best experts on this subject based on the ideXlab platform.
-
a virtual chinese hairy Brush Model for e learning
International Conference on Web-Based Learning, 2007Co-Authors: Bendu Bai, Kamwah Wong, Yanning ZhangAbstract:The increasing demands of education, reduction of study cost and study without location limitation have encouraged developers providing different types of learning and educational systems. This paper presents a virtual Chinese hairy Brush painting environment which can be used as a digital tool for learning or creating Chinese calligraphy or Chinese painting. The framework comprises two components: Brush geometry Model and Brush dynamic Model. Instead of simulating the Brush using bristles, we use points to simulate the whole Brush bundle, which can drastically decrease the complexity inherent in the conventional bristle-level approach; our Brush dynamic Model describes the behavior of the real Brush's deformation in terms of the interaction of the external and internal forces with the virtual writing paper. A spring network is derived to calculate the physical deflection of Brush according to the force exerted on it. A prototype system has been implemented based on this framework, with which high-quality digital painting and calligraphy artwork can be produced.
-
ICWL - A virtual Chinese hairy Brush Model for E-Learning
Lecture Notes in Computer Science, 1Co-Authors: Bendu Bai, Kamwah Wong, Yanning ZhangAbstract:The increasing demands of education, reduction of study cost and study without location limitation have encouraged developers providing different types of learning and educational systems. This paper presents a virtual Chinese hairy Brush painting environment which can be used as a digital tool for learning or creating Chinese calligraphy or Chinese painting. The framework comprises two components: Brush geometry Model and Brush dynamic Model. Instead of simulating the Brush using bristles, we use points to simulate the whole Brush bundle, which can drastically decrease the complexity inherent in the conventional bristle-level approach; our Brush dynamic Model describes the behavior of the real Brush's deformation in terms of the interaction of the external and internal forces with the virtual writing paper. A spring network is derived to calculate the physical deflection of Brush according to the force exerted on it. A prototype system has been implemented based on this framework, with which high-quality digital painting and calligraphy artwork can be produced.
Jacob Svendenius - One of the best experts on this subject based on the ideXlab platform.
-
Experimental Validation of the Brush Tire Model
Tire Science and Technology, 2009Co-Authors: Jacob Svendenius, Magnus Gäfvert, Fredrik Bruzelius, Johan HultenAbstract:The paper contains an experimental validation of the physically based Brush-tire Model toward the tire behavior in a number of different realistic conditions. Results of measurements performed with summer, winter, and studded tires on different road foundations such as wet and dry asphalt, basalt, snow, and ice are presented. The purpose behind the validation is to study the possibilities of using the Brush Model to estimate the friction coefficient from measurements or estimates of the longitudinal tire forces and tire slip. The sensitivity of the included tire parameters toward various factors that may change during normal run of the vehicle is also investigated.
-
Tire Modeling and Friction Estimation
2007Co-Authors: Jacob SvendeniusAbstract:New system technologies are continuously improving the performance of vehicles regarding comfort, stability, environmental stresses, and safety. Novel sensors are developed and used together with advanced control algorithms and faster and more accurate actuators to help the driver to maneuver the vehicle in a safer way. The physical traction limit set by the friction between the tires and the road can, however, not be overridden. The behavior of tires is, therefore, an important issue since it determines the possibilities to control the vehicle. One essential task for the vehicle control system is to be able to fully utilize these limits. Another is to assist the driver to choose an adequate driving style, adapted to the actual conditions. A method to derive the tire forces for simultaneous braking, cornering and camber, by combining empirical Models for the pure behavior of each of respective action is presented in the thesis. The method is based on the physical foundation brought by the simple, but well-suited Brush Model theory. The pure-slip tire Models can be given as empirical Models or as raw tabular data. The implementation is verified to be well-working and computationally sound and good results are obtained in validation with the available empirical data. A new type of on board Brush-Model based friction-estimator using the local measurements on the vehicle is also proposed. A major invention is the way of collecting the measurements into bins, such that the available data used for optimization is evenly weighted along the force and slip axis. Experimental data has been collected and evaluated to ensure the validity of the Brush Model during certain conditions. The estimator has been implemented and validated on a personal car. The wheel speed signal is an essential signal in many system applications. Based on problems observed during performed measurements, a few ways to reduce the noise on the signal, without adding any phase shift or time delay, are discussed in the thesis. (Less)
-
Validation of the Brush Model towards VTI-measurement data recorded at Hällered 2005
Technical Reports; TFRT, 2007Co-Authors: Jacob SvendeniusAbstract:The report shows a validation of the Brush tire-Model towards measurement data performed in the RFE-project within the IVSS-framework. The data is recorded by VTI at Volvos test track, Hallered. The winter tire, Continental ContiWinterContact TS810 215/55R16 and the summer tire, Continental ContiSportContact 225/45R17 91W are tested longitudinally and laterally at different conditions. A study of how the braking stiffness, the cornering stiffness and the friction varies with the varying conditions is performed.
-
Validation of the Brush Model towards VTI-measurement data recorded in Arjeplog 2006
Technical Reports; TFRT, 2007Co-Authors: Jacob SvendeniusAbstract:The report shows a validation of the Brush tire-Model towards measurement data performed in the RFE-project within the IVSS-framework. The data is recorded by VTI at Colmis Proving Ground in Arjeplog. The winter tire, Continental ContiWinterContact TS810 215/55R16, the summer tire, Continental ContiSportContact 225/45R17 91W, and the studded tire: Gislaved Nordfrost 3 215/55R16 are tested longitudinally and laterally at different conditions. A study of how the braking stiffness, the cornering stiffness and the friction varies with the varying conditions is performed.
-
A novel semi-empirical tyre Model for combined slips
Vehicle System Dynamics, 2005Co-Authors: Magnus Gäfvert, Jacob SvendeniusAbstract:A new tyre-force Model for simultaneous braking and cornering is presented, which is based on combining existing empirical Models for pure braking and cornering with Brush-Model tyre mechanics. The aim is to offer an easy-to-use, accurate Model for vehicle-handling simulations. On a working tyre the contact patch between the tyre and the road is, in general, divided into an adhesion region where the rubber is gripping the road and a sliding region where the rubber slides on the road surface. The total force generated by the tyre is then composed of components from these two regions. The Brush Model describes this in a mechanical framework. The proposed Model is based on a new method to extract adhesion and sliding forces from empirical pure-slip tyre Models. These forces are then scaled to account for the combined-slip condition. The combined-slip self-aligning torque is also described. A particular feature of the Model is the inclusion of velocity dependence, even if this is not explicitly present in the...
György Inzelt - One of the best experts on this subject based on the ideXlab platform.
-
the Brush Model of the polymer films analysis of the impedance spectra of au pt poly o phenylenediamine electrodes
Electrochimica Acta, 2006Co-Authors: Győző G. Láng, Mária Ujvári, T.a. Rokob, György InzeltAbstract:In the "Brush Model" of polymer modified electrodes it is assumed that the polymer film consists of short and long polymer chains forming bundles in such a way that only a small part of the metal substrate surface is covered by the polymeric material. The results of electrochemical impedance spectroscopy, cyclic voltammetry and surface stress measurements confirm that a Brush-like ordering of the polymer chains on the metal surface is a realistic description of the surface film structure. Physicochemical parameters obtained from electrochemical impedance spectra for poly(o-phenylenediamine) films on platinum in contact with I M HClO 4 or 0.5 M H 2 SO 4 solution were analyzed on the basis of the Brush Model. The characteristic parameters derived from the impedance spectra of different electrodes were compared.
-
The Brush Model of the polymer films—analysis of the impedance spectra of Au,Pt|poly(o-phenylenediamine) electrodes
Electrochimica Acta, 2006Co-Authors: Győző G. Láng, Mária Ujvári, T.a. Rokob, György InzeltAbstract:In the "Brush Model" of polymer modified electrodes it is assumed that the polymer film consists of short and long polymer chains forming bundles in such a way that only a small part of the metal substrate surface is covered by the polymeric material. The results of electrochemical impedance spectroscopy, cyclic voltammetry and surface stress measurements confirm that a Brush-like ordering of the polymer chains on the metal surface is a realistic description of the surface film structure. Physicochemical parameters obtained from electrochemical impedance spectra for poly(o-phenylenediamine) films on platinum in contact with I M HClO 4 or 0.5 M H 2 SO 4 solution were analyzed on the basis of the Brush Model. The characteristic parameters derived from the impedance spectra of different electrodes were compared.
-
Analysis of the impedance spectra of Pt|poly(o-phenylenediamine) electrodes - Hydrogen adsorption and the Brush Model of the polymer films
Journal of Electroanalytical Chemistry, 2004Co-Authors: Győző G. Láng, Mária Ujvári, György InzeltAbstract:Abstract Electrochemical impedance spectra obtained for poly( o -phenylenediamine) films on platinum in contact with 0.5 M H 2 SO 4 solution were analyzed on the basis of the Brush Model elaborated for conducting polymer films on electrodes. It is assumed that the polymer film consists of short and long polymer chains forming bundles in such a way that only a small part of the metal substrate is covered by the polymeric material. The analysis of the impedance spectra taken at several potentials in the region of hydrogen adsorption on platinum supports the validity of the Model. The Model has been tested also by varying the film thickness and the roughness of the platinum substrate.
-
Possible origin of the deviation from the expected impedance response of polymer film electrodes
Electrochimica Acta, 2001Co-Authors: Győző G. Láng, Mária Ujvári, György InzeltAbstract:Abstract In order to explain the impedance spectra of polymer film electrodes a modification of the porous Model is suggested based on experimental observations. In this ‘Brush’ Model it is assumed that a polymer film consists of short and long polymer chains forming bundles in such a way that only a small part of the metal substrate is covered by the polymeric material. The oxide layer formation on the gold substrate attests the reality of this physical Model. The Model has been tested by the analysis of the impedance spectra of Au/poly( o -phenylenediamine) electrodes in contact with 1 mol dm −3 perchloric acid. The spectra were taken at different potentials and the film thicknesses as well as the roughness of the gold substrate were systematically varied.
