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Technical Paper
2013-11-27
Uma Maheshwar Vanamala, Raja Rao koganti
The main characteristic of vehicle moving on road is related to its response to the drivers command and to environmental factors affecting the direction of motion of vehicle. The two basic problems in handling the vehicle are control of vehicle along the desired path and stabilization of the direction of motion of vehicle against external disturbances. The vehicle with best handling characteristics is the vehicle which can always be controlled by the driver. While parking the vehicle and doing sharp turnings the vehicle with two wheel steering cannot be more significant. The two wheel steering system takes large radius of turning and requires more space to take turn. Hence four wheel steering is preferable than two wheel steering systems. A multi-function four wheel steering system could improve directional stability at high speeds, sharp turning performance at low speeds, and parking performance of a vehicle. Generally there are three types of steering systems which include front wheel, rear wheel and four wheels.
Technical Paper
2012-04-16
Richard Topping
An overview of existing and alternative forms of vehicle understeer/oversteer expressions is presented. New forms are derived consistent with conceptual extensions to the configurations of the vehicle's steering system, the driving mode - steady-state or transient, and the responses - path curvature or yaw velocity. Derivation of all understeer expressions is presented with a consistent use of the Ackermann reference case and the related “Ackermann vehicle” construct. The vehicle is otherwise represented in a traditional manner as a bicycle model operating in the linear range consistent with small angle approximations. The vehicle's steering system is assumed to be more generally configured with four-wheel steer and active or steer-by-wire actuation at both axles. The actuation is assumed to allow the introduction of significant speed sensitivity to the effective overall steering ratios. Discussion is devoted to the significance of this speed sensitivity on test results and the determination of the mean reference steer angles.
Technical Paper
2011-04-12
Mynor Roberto Ronci, Paola Artuso PhD, Enrico Bocci
In this paper a four independent wheel-steering system and its application on the HOST prototype are presented. The prototype is a heavy duty vehicle with four wheel motors controlled by wire, so that each wheel is mechanically not-linked to the other ones and has four degrees-of-freedom. Each wheel has an electric steering actuator to move the wheels around the steering axis, which is controlled by wire. The first part of the work deals with the model determination, reducing the four degree-of-freedom system into a one degree-of-freedom system. In the second part, the relationship between the rotations of each wheel and the linear movement of the electric steering is presented. In the third part the steering ratio is calculated and a parameter to reduce the slip angle is defined. In this way a four independent wheel steering model has been developed and applied to the specific characteristics of HOST. Finally the vehicle handling has been tested through simulations of steering-pad and moose-test, in order to verify the stationary and dynamic handling behavior.
Technical Paper
2011-04-12
Saurav Talukdar, Muhammad Adeel Awan, Dr. Amer Hameed
This paper focuses on developing a Low Cost IMU integrated with GPS for vehicle state estimation. Knowledge of vehicle states can help design control systems which take these states as an input. Technological advancements in Micro-Electro-Mechanical Sensors (MEMS) have made accelerometers and gyroscopes economical. However, these MEMS based low cost sensors have inherent noise which accumulates with the passage of time and therefore makes their output unreliable. GPS measurements can be used to rectify the inertial sensor errors. Calibration as well as hardware implementation has been discussed in detail. Emphasis is on measurement of body slip angle. Simulations as well as actual results are being presented. Conclusion is being made on the performance of this system.
Technical Paper
2008-04-14
Jie Zhang, Yunqing Zhang, Liping Chen, Jingzhou Yang
Active steering systems can help the driver to master critical driving situations. This paper presents a fuzzy logic control strategy on active steering vehicle based on a multi-body vehicle dynamic model. The multi-body vehicle dynamic model using ADAMS can accurately predict the dynamic performance of the vehicle. A new hybrid steering scheme including both active front steering (applying an additional front steering angle besides the driver input) and rear steering is presented to control both yaw velocity and sideslip angle. A set of fuzzy logic rules is designed for the active steering controller, and the fuzzy controller can adjust both sideslip angle and yaw velocity through the co-simulation between ADAMS and the Matlab fuzzy control unit with the optimized membership function. To ensure the design of high-quality fuzzy control rules, a rule optimization strategy is introduced. The fuzzy control parameters are optimized and analyzed by a combined optimization algorithm (the Simulated Annealing method (SA) and the Nonlinear Programming Quadratic Line search (NLPQL) method) combined with the response surface model (RSM).
Technical Paper
2008-04-14
Takeshi Katayama, Yoshiki Yasuno, Tomoaki Oida, Masayuki Sao, Masayuki Imamura, Nagatoshi Seki, Yasuharu Satou
4 wheel Active Steer (4WAS), which controls all four steering angle, is developed first in the world. This system achieves dynamic performance with secure and invigoration feel on higher level, based on active steer technology of rear axle. This paper describes aim and necessity of all four steering control, and introduces outline and efforts of this system.
Technical Paper
2007-04-16
M. A. El-Nashar, M. B. Abdelhady, W. A. Oraby, S. R. El-Sinawy
In this work, a theoretical investigation of four-wheel steering (or shortly 4WS) system is presented using a linear model to simulate vehicle handling characteristics. This model incorporates driver';s operation. The simulation concerns the vehicle in straight running while the vehicle is subjected to side wind excitation. Limitations of measurements in practice are supporting the implementation of limited state feedback systems instead of those which are based on full state feedback information. Therefore, the well known Kalman filter algorithm is used in this work to design a practical 4WS control strategy. This practical system uses only feedback signals of lateral acceleration and front steering angle to obtain the control law. Measurement noise is taken into account and results are generated to obtain the step response of the outputs of interest. Comparison between this system, classical 4WS system with LQR feedback gains and the conventional 2WS system are obtained and conclusions are drawn on the benefits and practical implications of these intelligent 4WS.
Technical Paper
2006-10-31
Hassan Shraim, Mustapha Ouladsine
This paper describes the problem of vehicle trajectory tracking control in the plane (X, Y). While following this trajectory, and to test some of the extreme cases, several types of faults are produced. Some of these faults may be described by a decrease in tires inflation pressures. For that reason, an analytical model representing the comportment of the vehicle and integrating these faults is proposed. In order to use this model in the control, several validations are made by the advanced simulator VE-DYNA. As a second step of this work, the controller design is made; this controller acts on the steering angle and on the torques of the wheels. It is based on the principles of the predictive control. The controller is tested in two cases: in the normal case where the task is to follow a predefined trajectory without faults, and in the other case where the task is the same but faults described by tires pressures decrease are produced. Computer simulations pointed out the effectiveness of the proposed controller.
Technical Paper
2006-10-16
Codrin-Gruie Cantemir, Gabriel Ursescu, Lorenzo Serrao, Giorgio Rizzoni, James Bechtel, Thomas Udvare, Michael Letherwood
This paper presents an all-wheel-drive (AWD) hybrid electric vehicle (HEV) design approach for extreme off-road applications. The paper focuses on the powertrain design, modeling, simulation, and performance analysis. Since this project focuses on a military-type application, the powertrain is designed to enhance crew survivability and provide several different modes of limp-home operation by utilizing a new vehicle topology -herein referred to as the island topology. This topology consists of designing the vehicle such that the powertrain and other equipment and subsystems surround the crew compartment to provide a high level of protection against munitions and other harmful ordnance. Thus, in the event of an external shield penetration, the crew compartment remains protected by the surrounding equipment - which serves as a secondary shield. The powertrain system principally consists of two internal combustion engines which are coupled to three electric machines using two planetary gear sets, and also includes other transmission elements.
Technical Paper
2006-04-03
Philip Koehn, Michael Eckrich, Hendrikus Smakman, Arnd Schaffert
This paper is supposed to address the BMW approach to the challenge of integrating chassis control systems and it highlights the major issues that have to be addressed. It points out possible solutions for scalable functional and hardware configurations for variable chassis control system combinations. A short outlook is given at possible functional benefits of an integrated structure. Finally, aspects such as components costs (e. g. for sensors and ECUs) as well as reactions on system failures and degradability have to be looked at.
Technical Paper
2006-04-03
Sankar K Mohan, Anupam Sharma
There is increasing demand for enhancement of stability and handling performance in modern automobiles. Active yaw moment generation mechanisms are essential for implementing intelligent stability control schemes. Two mechanisms being considered here are Torque Vectoring Rear Axle and Four Wheel Steering System. Torque Vectoring Axle allows active control of wheel speed ratio and torque distribution typically through the use of wet clutch/brake system and secondary gearing. Four wheel steer systems usually have conventional steering in the front axle and an active steering system in the rear axle. The steering logic is based on improved performance in terms of turning radius at low speeds and directional stability and response at higher speeds. In this study, a lumped parameter, large amplitude, non-linear vehicle model of a rear wheel drive, high-performance vehicle is used. The simulation is executed on a skid pad as well as on a prescribed test track using a closed loop driver-vehicle system.
Technical Paper
2006-04-03
Evren Ozatay, Samim Y. Unlusoy, A. Murat Yildirim
This paper describes the use of a designed Fuzzy Logic Control for the purpose of integrating the driver’s steering input together with the four-wheel steering system (4WS) in order to improve the vehicle’s dynamic behavior with respect to yaw rate and body sideslip angle. The control objective is to obtain zero body sideslip angle by a two-dimensional rule table, which is created based on the error and on the change in the error of sideslip angle that is to be minimized. The dynamics of the model is developed with a three-degree of freedom nonlinear vehicle model including roll dynamics. The Magic Formula is applied in order to formulate the nonlinear characteristics of the tires. A lane change and steady state cornering simulations are performed to show the effectiveness of the control on transient motion body sideslip angle and yaw rate response time behaviors. During simulations, comparisons are done with the two-wheel steered vehicle and the control techniques studied previously.
Technical Paper
2005-11-01
Xiaoming Shen, Fan Yu
In this paper, we proposed a novel integrated vehicle chassis control configuration, which is based on the combination of vehicle vertical and lateral motion controls. Focusing on the improvement of vehicle handling and riding performance, particularly the active safety under critical driving condition, the purpose of Active Suspension (AS) in the integrated system is to achieve ride comfort quality and to provide more tyre cornering ability near the cornering force saturation regions, while the effect of Four Wheel Steering (4WS) is expected to eliminate the body side slip angle and to achieve an ideal yaw rate model following.
Technical Paper
2005-04-11
Andrea Morgando, Mauro Velardocchia, Davide Danesin, Edoardo Rossi
A four wheel steer control logic is described. A first control logic release, obtained during previous research activity, is based only on feed forward (F.F.) but is here upgraded merging closed loop control (C.L.). Integration between F.F. and C.L. is described. Rear steering electromechanical actuator frequency response is analyzed, in order to consider its not ideal behaviour during control logic design. Several simulation are performed to qualitatively evaluate the error committed considering an ideal actuator during the control logic design. Specific manoeuvres are chosen to investigate about active system influence on vehicle handling; a 14 degrees of freedom vehicle model is validated in order to compare simulation results with experimental data. Simulated manoeuvres and analogous road tests are then compared and control logic efficacy for different longitudinal velocities is evaluated, as well as for different vehicle working conditions (weight, tyres change etc.) and different reference target behaviours.
Technical Paper
2005-04-11
Andrea Morgando, Mauro Velardocchia, Davide Danesin, Edoardo Rossi
Through a single track model, correspondence between typical frequency analysis coefficients and test driver's opinion developed after experimental tests has been stated. Benchmark analysis of several vehicles, considered significant, has been carried out as well as a sensitivity analysis of vehicle behavior depending on passive design parameters, such as vehicle sideslip stiffness and tyre relaxation length. It led to the definition of the different transfer function capable of describing passive vehicle linear behavior; vehicle performance limits, due to unbridgeable physical phenomenon, has been also considered. 4WS vehicle chance to overcome these limits has been investigated, depending on rear steering control logic complexity. Vehicle frequency response has been then analyzed for different longitudinal velocity, introducing thus the concept of “natural vehicle”. The design of a four wheel steer system control logic, based only on feed forward, is described. The control logic aim is to improve active vehicle handling and its setting is controlled by a limited number of parameters.
Technical Paper
2005-04-11
Namir J. Zara
The four wheel steer system better known as the Quadra Steer system (QS4) is a system that provides steering control of the rear wheel of long based pickups and large sport utilities. Analysis was utilized to develop Rear/Front (R/F) steering algorithm with the vehicle in it's normal mode which is characterized as vehicle at curb + 2 passengers or GVW/RGAWR on dry surface. Analysis utilized BZ3 control response simulation model to conduct this study. This dynamic model was used to evaluate key vehicle handling parameters to validate and optimize the algorithm.
Technical Paper
2004-05-04
Miguel A. Vilaplana, Douglas J. Leith, William E. Leithead, Jens Kalkkuhl
This paper presents a new steering controller for cars equipped with 4-wheel steer-by-wire. The controller commands the front and rear steering angles with the objective of tracking reference sideslip and yaw rate signals describing the desired car lateral dynamics. In addition, the controller automatically rejects any disturbances in sideslip and yaw rate caused, for example, by μ-split braking manoeuvres or lateral wind gusts. The structure of the controller is based on a simplified model of the lateral dynamics of 4-wheel steering cars. This structure allows an originally complex multivariable control design problem to be broken down into two simpler single-input, single-output (SISO) control design problems by means of the Individual Channel Design (ICD) methodology. Within the proposed structure, individual sideslip and yaw rate controllers, valid for varying vehicle speed, can be designed using classical linear control design techniques. An anti-windup scheme has been incorporated into the steering controller to mitigate the effects of the saturation or failure of the rear steering actuators.
Technical Paper
2004-03-08
Mauro Velardocchia, Andrea Morgando, Aldo Sorniotti
The paper presents a 4-wheel-steering (4WS) control strategy devoted to reduce the turn diameter for small longitudinal speed values and to obtain a yaw rate damping effect in dynamic manoeuvres. Moreover, the 4WS active system conceived produces compensation both for lateral wind and road irregularities. The main results obtained through a functional vehicle model are presented. 4WS was integrated with a Vehicle Dynamics Control (VDC), which was improved for turn while braking manoeuvres. The results due to integration were very good, with a reduction of both systems interventions. Finally, a VDC-4WS-Active Roll Control (ARC) integration was tried, based on only one reference body yaw rate for all the active systems. The main results obtained are presented and discussed.
Technical Paper
2004-03-08
Colm O'Kane, Sean Timoney
An algorithm was developed for a speed-dependent four-wheel steering system for a Formula SAE car. A linear bicycle model was implemented using the MATLAB and SIMULINK software packages. Various control laws were investigated for the rear steer angle with the objective of reducing the sideslip angle. A full 3D model of the vehicle incorporating weight transfer and tire non-linearity was then developed using the DADS software. An algorithm developed using the linear model with the aim of reducing vehicle sideslip angle was implemented in the nonlinear model. It is shown that this algorithm can improve the dynamic performance for both high-speed and low-speed maneuvers.
Technical Paper
2003-03-03
L. Pascali, P. Gabrielli, G. Caviasso
Purpose of this work is to investigate, through a virtual analysis in multi body environment, how to use a four wheel steering system (4WS) to improve vehicle handling and comfort performance. Working only on rear axle, the idea is to define a suspension layout that maximizes the comfort using the mechanical approach, while the handling performance is demanded to the active system. The vehicle used for the theoretical study is an Alfa Romeo 166 3.0 V6. The standard vehicle has been mechanically modified by changing the original rear suspension, a multilink geometry, with a Mc-Pherson layout designed to maximize longitudinal comfort performances. Then an active system, which controls rear steering angles, has been integrated in the rear axle in order to maximize handling performance.
Technical Paper
2002-07-09
Bogdan Fijalkowski
An automotive vehicle steering is achieved not only by means of hand steering wheel (SW) but also by varying actual valued of the angular velocity and sense of rotation of all the electromechanical/mechanoelectrical (E-M/M-E) steered, motorized and/or generatorized wheels (SM&GW) for all-wheel driven (AWD) × all-wheel steered (AWS) automotive vehicles. The betterment tri-mode hybrid steer-by-wire (SBW) AWS diversion automotive high-tech has made significant progress during the 1990s. An evolutionary factor behind this has been the increasing requirements or an active safety as well as ride comfort and handling (RC&H) of automotive vehicles. A major contribution to this progress is the introduction and fast growing application rate of electrically powered and mechatronically controlled rack-and-pinion (R&P) steering gears.
Technical Paper
2002-05-07
Vahraz Nikzad Siahkalroudi, M. Naraghi
Control schemes and strategies of a 4WS vehicle are studied, where schemes are single and dual steering and strategies are zero side slip (ZSS), zero yaw rate (ZYR) and model reference tracking. While Single steering scheme controls only the front steering angle of vehicle, dual steering controls both rear and front steering angles independently. A special model reference tracker, which smoothes vehicle transient response and yields the same steady state yaw behavior as 2WS vehicle, is finally proposed. The dynamic models are a 2DOF linear handling model for controller and a 3DOF nonlinear handling model with CALSPAN tire coefficients for simulation. Simulation results show that while dual steering scheme can effectively control yaw rate and lateral velocity references, single steering scheme is not able to track both of the mentioned variables. It is also shown that the proposed reference is able to improve the handling properties of vehicle.
Technical Paper
2002-05-07
Vahraz Nikzad Siahkalroudi, M. Naraghi
This paper discusses about a LQR controller as optimal regulator, which is suited for state variable regulation and tracking as a full state feed back controller, Zero side slip (ZSS) and zero yaw rate (ZYR) compensators. ZSS and ZYR are controllers that force the linear system to regulate the steady state response of side slip state variable (have linear relation with lateral velocity) and yaw rate state variable respectively in linear model. As dynamic models, a 2 DOF linear handling model with yaw rate and lateral velocity variables is used as controller model, and a 3 DOF nonlinear model with yaw rate, lateral velocity and roll variables and CALSPAN tire coefficients is proposed for simulations. Results show that in spite of LQR controller, which yields suitable results in both linear and nonlinear models and both regulation and tracking strategies, zero steady state compensators (ZSS and ZYR) could not yield acceptable results in nonlinear model that simulates real response of vehicle; in addition not to have flexible nature (like LQR) to perform a multi purpose control strategies.
Technical Paper
2002-05-07
Vahraz Nikzad Siahkalroudi, M. Naraghi
A dual steering control, where steering angle of both rear and front wheels are controlled independently, and single rear steering control of a 4WS vehicle is studied. In this regard, a Time Delay Controller (here after called TDC) is proposed. The TDC performance is compared with the LQR optimal control method. Control schemes are based on the yaw and lateral velocity reference model following. A 3DOF linear vehicle model comprising yaw, lateral and roll motions is used to design the control laws. The time delay controller is a model reference tracker that estimates disturbances such as side wind, road irregularities and actual model nonlinearities, and considers them into the linear controller model. Simulations based on steady state cornering and lane change maneuvers are presented. To establish the sufficient level of model complexity, a 3-DOF nonlinear simulation model comprising yaw, lateral and roll motions with CALSPAN tire coefficients is used.
Technical Paper
2002-03-04
Tokihiko Akita, Katsuhiko Satoh, Michael C. Gaunt
Sport Utility Vehicles (SUV) and light duty trucks have gained in popularity for the last several years and the demand for more car-like behavior has increased, accordingly. Two areas for potential improvement are vehicle stability and maneuverability while parking. 4WS (4 wheel steering system) is known as an effective solution to stability and low speed maneuverability. In this paper, we identify a new systematic design method of two degree of freedom vehicle state feedback control algorithm that can improve vehicle stability, and show its control effects for a SUV with trailer towing. Low speed maneuvering is improved when the rear tires are steered in negative phase relative to the front tires. However with a large rear steer angle at low speed, the vehicle's rear overhang tracks a wider swing-out path than a 2WS vehicle. For this concern, we propose a new swing-out reduction control algorithm.
Technical Paper
2000-06-12
Bambang Sampurno, H. A. Tjokronegoro, I. M. Farida, W. Arismunandar
In this paper will be presented an alternative of feedforward controller (FFC) system to overcome four-wheel-steering weaknesses. The system estimates vehicle output parameters that consists of lateral acceleration (v), roll rate (ϑ) and yaw rate (φ) as well as the correct input parameters of vehicle that consists of longitudinal sped (Uo) and steering wheel (δsw). To estimate vehicle output parameters used will be full car mathematical model. The estimated vehicle output parameters together with given vehicle input parameters are used to estimate understeer coefficient (Ku). Finally, it will be used to compute the correct vehicle input parameters required by the 4WS system.
Technical Paper
2000-06-12
Lan Jiang, Yuqing Wang, Masao Nagai
This study investigates a control strategy using the front steering angle control to improve the handling and stability of heavy-duty vehicles as a possible substitute for four-wheel steering (4WS) system. The effective steering input is regulated through the state feedback computed by the optimal control theory suggested in this research, to adapt the closed system to the changes of some factors depending on running situations, such as velocity and center of gravity. Direct moment control with a simple auto-tuning proportion controller is also integrated in the compensation system, wherein yaw moment and roll moment are applied to decrease side slip angle and roll angle respectively. A double-cost-function LQR methodology (DLQR) is developed to compute the value of the front steering angle compensation. In addition to traditional LQ cost function, another index called target cost function with a free form is introduced in DLQR to express physical requirements more plainly to determine reasonable weighting matrices.
Technical Paper
2000-06-12
I. Nyoman Sutantra, Yusuf Kaelani
Turning at high speed, doing sharp turning at low speed, and doing parking are three critical motions of a vehicle needed to be considered. This research studied dynamic characteristics of a multi-function four-wheel steering system that could improve directional stability of vehicles on turning at high speed, minimize radius of turning of vehicles while doing sharp turning at low speed, and reduce spaces needed on parking motion. Four methods were used to study dynamics characteristics of a multi-function four-wheel steering system. Those four methods were method of constant yaw rate, method of equal side slip angle, method of zero side slip, and method of negative side slip or controlling side slip angle. The results of the study show that the method of zero side slip is the best method to determine rear wheel angle needed for a vehicle doing parking motion in order to minimize radius of turn. When a vehicle is turning at high or medium speed, rear wheel angle needed should be determined by method of negative side slip angle.
Technical Paper
1998-02-23
Akiya Taneda, Toshihiko Yamanaka
In recent years improved emissions control, energy saving devices and safety features have become the driving forces in automotive manufacturing and technology. We have developed the Active-Rear-Steer system with an electro-mechanical actuator, which is an improved safety feature. It also features availability to mass production and a compact size. The system is highly responsive, increasing vehicle performance and stability, thus, enhancing the active safety of the vehicle.
Technical Paper
1998-02-23
Kozo Fujita, Kaoru Ohashi, Katsumi Fukatani, Syouichi Kamei, Yasuhiro Kagawa, Hideo Mori
A new active rear steer (ARS) system has been developed. ARS is an electric four wheel steering system controlled by new logic(designed by H∞-μ synthesis) which maintains good control performance even if the vehicle parameters and /or road surface conditions are changed. ARS control is a typical technology to prevent vehicle side -slip in linear region of tire characteristic. This system offers easy control and reduces vehicle behavior of yawing motion before approaching critical limit. By combining ARS and vehicle stability control (VSC), it is possible to support driving precisely from normal driving to excessive driving. This paper describes the details of this new system which has been installed on 1997 model TOYOTA ARISTO for practical use in JAPAN.
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