Showing papers in "Vehicle System Dynamics in 1995"
TL;DR: A broad review of the developments that have taken place within the past thirty years in the field now known as Advanced Vehicle Control Systems (AVCS) is provided in this paper, where the main body of the paper reviews the relevant literature in lateral, longitudinal and integrated control of road vehicles.
Abstract: This paper provides a broad review of the developments that have taken place within the past thirty years in the field now known as Advanced Vehicle Control Systems (AVCS). This long time horizon was chosen to ensure that significant findings from earlier generations of work are not overlooked today. Following a history of the international development of AVCS, several methods of classifying AVCS are introduced. The main body of the paper reviews the relevant literature in lateral, longitudinal and integrated control of road vehicles and summarizes the most significant findings from this work.
285 citations
TL;DR: In this article, the lateral control of vehicles during high-g emergency maneuvers is addressed, and models of the vehicle dynamics are developed, showing the accuracy of the different models under low and high g conditions.
Abstract: SUMMARY Recent research on autonomous highway vehicles has begun to focus on lateral control strategies. The initial work has focused on vehicle control during low-g maneuvers at constant vehicle speed, typical of lane merging and normal highway driving. In this paper, and its companion paper, to follow, the lateral control of vehicles during high-g emergency maneuvers is addressed. Models of the vehicle dynamics are developed, showing the accuracy of the different models under low and high-g conditions. Specifically, body roll, tire and drive-train dynamics, tire force saturation, and tire side force lag are shown to be important effects to include in models for emergency maneuvers. Current controllers, designed for low-g maneuvers only, neglect these effects. The follow on paper demonstrates the performance of lateral controllers during high-g lateral emergency maneuvers using these vehicle models.
179 citations
TL;DR: In this paper, the authors investigated the track deterioration due to ballast settlement in the Tokaido Shinkansen and proposed the coefficient of track deterioration, which was later extended to track irregularity.
Abstract: SUMMARY In 1950's, studies on track deterioration due to ballast settlement were initiated in Japan. These included those not only on the settlement of ballast, but also on the ballast acceleration which caused the ballast settlement and proposed the coefficient of track deterioration. The design of the track of the Tokaido Shinkansen depended on it. Since then the studies have been continued up to now on the track state related to maintenance work, on the growth of track irregularity and finally on the convergence of track irregularities¨.
127 citations
TL;DR: In this article, a bibliographical list classifies the extensive literature related to the dynamic analysis and control design aspects of advanced ground vehicle suspension systems, restricted to the design of advanced suspensions for ride quality and safety.
Abstract: SUMMARY This bibliographical list classifies the extensive literature related to the dynamic analysis and control design aspects of advanced ground vehicle suspension systems. It is restricted to the design of advanced suspensions for ride quality and safety. Brief generalized notices and definitions are presented.
116 citations
TL;DR: In this paper, the authors investigated two strategies for controlling a semi-active damper to track a prescribed force demand signal: (i) open loop control, using a model of the damping force versus velocity characteristics; and (ii) force feedback (closed loop) control.
Abstract: SUMMARY Two strategies are investigated for controlling a semi-active damper to track a prescribed force demand signal: (i) ‘open loop’ control, using a model of the damping force versus velocity characteristics; and (ii) force feedback (closed loop) control. The damping characteristics and switching transients of a prototype damper were measured, and used to develop a mathematical model of the dynamics of the damper. The two control strategies were investigated using an idealised (constant velocity) test. Their performance was also simulated and measured under realistic operating conditions using the Hardware-in-the-Loop testing method. Open loop damper control was generally found to give superior performance to force feedback control, due to its smaller phase lag at high frequencies.
87 citations
TL;DR: In this article, three alternative theoretical models of the dynamic behaviour of railway track in the frequency range 50-6000 Hz are described, and various physical phenomena of importance to rolling noise generation are pointed out.
Abstract: SUMMARY Three alternative theoretical models of the dynamic behaviour of railway track in the frequency range 50–6000 Hz are described. Using these models various physical phenomena of importance to rolling noise generation are pointed out, and the advantages and short-comings of the three models are compared. Finally, laboratory measurements are described in which the vertical and lateral dynamic stiffnesses of rail fastener systems has been measured under preload in the range 100–1000 Hz.
85 citations
TL;DR: In this paper, the authors look at the developments that have taken place in this area, the background to the need for sophisticated models, the improvements in accuracy that can result and some of the difficulties in applying these techniques to the modelling of real situations.
Abstract: SUMMARY The dynamic behaviour of railway vehicles has been the subject of study for over a century but the advances in computing technology in the last few years have led to a very rapid development in the use of numerical techniques for solving railway vehicle dynamics problems. As these techniques have developed, and have been applied to ever more complex problems, the modelling of the vehicle components has increased in importance. Mathematical models of railway vehicles may now include components such as swing links, air-springs, trailing arm suspensions, load sensitive friction dampers, rubber bushes with hysteresis etc, all of which require sophisticated modelling techniques to produce accurate results. This paper looks at the developments that have taken place in this area, the background to the need for sophisticated models, the improvements in accuracy that can result and some of the difficulties in applying these techniques to the modelling of real situations.
78 citations
TL;DR: In this article, a complete set of constraints for the road disturbance transfer functions in a quarter car model of an automotive active suspension, for typical choices of measured outputs, is derived, and certain integral relationships are shown to follow from the derived transfer function constraints.
Abstract: SUMMARY A complete set of constraints is derived for the road disturbance transfer functions in a quarter car model of an automotive active suspension, for typical choices of measured outputs. It is shown that any road disturbance responses which are achievable using “full state feedback” can be achieved, to within an arbitrary small tolerance, using a dynamic compensator measuring suspension deflection only. Also considered are the disturbance responses to loads acting on the sprung mass, and a complete set of constraints is derived for these. It is shown that road disturbance and load disturbance responses can be determined independently if suspension deflection and sprung mass velocity are measured. Indeed, any responses achievable separately with “full measurements” can be approximated together to an arbitrary small tolerance. Certain integral relationships are shown to follow from the derived transfer function constraints. These relationships imply fundamental limitations for certain responses (e.g. ...
78 citations
TL;DR: In this paper, a mathematical model of a hydraulic shock absorber is developed for vehicle simulations and has seven parameters which can be determined by simple dynamic measurements on a test damper.
Abstract: SUMMARY A laboratory rig for testing hydraulic dampers using the ‘hardware-in-the-loop’ method is described, and the accuracy of the test method is investigated. A mathematical model of a hydraulic shock absorber is then developed. The model is suitable for vehicle simulations and has seven parameters which can be determined by simple dynamic measurements on a test damper. The shock absorber model is validated under realistic operating conditions using the test rig, and the relative importance of various features of the model on the accuracy of vehicle simulations is investigated.
70 citations
TL;DR: In this paper, an effective time domain method for simulating the vertical vehicle-track interactions for low and high frequencies is presented, where the number of sleepers to be considered is chosen so that the infinite extension of the track can be dealt with approximately.
Abstract: SUMMARY An effective time domain method for simulating the vertical vehicle-track interactions for low and high frequencies is presented. To be able to investigate the effects of local defects of the track (eg voided sleepers) on contact forces and loads and long-term deterioration of track components, a discrete track model based on finite elements is necessary. The track model developed is extremely accurate and is able to consider irregularities and nonlinearities in the track structure. The number of sleepers to be considered is chosen so that the infinite extension of the track can be dealt with approximately. For excitation due to short wavelengths like short pitch corrugation or wheel flats, nonlinear contact mechanics has to be considered. The time-step integration algorithm is based on a modal decomposition of linear substructures and is therefore absolutely stable. The method includes the effects of moving masses and is valid for train speeds up to 500 m/s. The capacity of the algorithm is demon...
64 citations
TL;DR: Three theoretical models, simulating the dynamic behaviour of railway tracks at frequencies up to 5 kHz are presented, and experimental results obtained on several European tracks are presented.
Abstract: SUMMARY Three theoretical models, simulating the dynamic behaviour of railway tracks at frequencies up to 5 kHz are presented in a companion paper [1]. In this paper, experimental results obtained on several European tracks are presented. The validity of the models is assessed by means of comparisons between experiments and simulations: generally a good agreement is found. Recommendations are given for further improvements.
TL;DR: In this article, a fuzzy control system for the clutch engagement of an automated manual transmission is presented, which is skillful to estimate the driver's will from the accelerator pedal operation.
Abstract: SUMMARY This paper presents a fuzzy control system for the clutch engagement of an automated manual transmission. The servomechanism is assembled with a three-port pneumatic pressure-proportional valve and a position-sensing cylinder which control the release-lever displacement of 25 mm within the position preciseness of 0.1 mm against maximum spring load of 2kN. The fuzzy system is skillful to estimate the driver's will from the accelerator pedal operation. The servomechanism is mounted on a commercial vehicle with 4-ton pay-load. The system parameters are set up by bond graphs simulation and empirical performance tests are carried by using an oil-hydraulically operated engine-vehicle testing rig with a maximum torque capacity of 400 Nm.
TL;DR: In this article, the optimal design of the four wheel steering (4WS) system of the ground vehicle is studied and two new designs of the VSF 4WS system are proposed and their performances are compared with the optimal 4WS systems and the existing VSF4WS system.
Abstract: SUMMARY Optimal design of the four wheel steering (4WS) system of the ground vehicle is studied. 4WS vehicles with the optimal control scheme are considered first. General formulation of the optimal control law is developed based on the linear quadratic regulator theory. The vehicle speed function (VSF) based 4WS vehicle with a simple feedback controller is considered as a special case of the optimal system. Two new designs of the VSF 4WS system are proposed and their performances are compared with the optimal 4WS systems and the existing VSF 4WS system. The first system is designed for the maximum stability while the second system is designed to emulate the response of the optimal 4WS vehicle. Advantages of the new VSF designs are discussed.
TL;DR: In this article, the authors reviewed key developments in applications of advanced control methods to automotive systems, including engines, suspension systems, traction systems, steering systems and those for automated highway systems.
Abstract: SUMMARY This paper reviews key developments in applications of advanced control methods to automotive systems. Such applications appear in many aspects of vehicle controls. We will examine representative application areas, which include engines, suspension systems, traction systems, steering systems and those for automated highway systems (AHS). Each area is examined from the viewpoint of modeling and control algorithm development. Useful control theories for automotive application are briefly reviewed for better understanding of the applicability of these theories.
TL;DR: In this article, the results of a parametric sensitivity analysis of a five-axle tractor-semitrailer vehicle combination using 3-DOF linear yaw/plane model are presented.
Abstract: This paper presents the results of a parametric sensitivity analysis of a five-axle tractor-semitrailer vehicle combination using 3-DOF linear yaw/plane model. The first order logarithmic sensitivity functions are derived with respect to several vehicle design parameters. For stabilization of the vehicle's directional behaviour a fairly new control concept called "Active Unilateral Braking Control (AUBC)" acting on the tractor rear wheel's in order to produce a stabilizing yaw torque is investigated. The AUBC system improves not only the directional stability, but also affects the roll dynamics of the vehicle. The sensitivity of the controlled vehicle system with linear quadratic controller (LQR) is also examined, a robust controller design procedure is proposed as a result of the sensitivity analysis. The robustness of this controller in the presence of both internal (including parametric uncertainties, non-linear dynamics) and external disturbances (such as road irregularities and side wind) allows its implementation with confidence with a non-linear vehicle model. The applicability of this control system to a non-linear vehicle model is tested using a 34 DOF, non-linear vehicle model of the tractor-semitrailer combination. (A)
TL;DR: In this article, the authors describe the development of an adaptive control algorithm for active suspension systems based on optimal regulation methods, which will automatically tune at start-up to changed vehicle conditions and adaptively re-tune to changes in driving conditions (in particular road generated disturbances).
Abstract: SUMMARY The paper describes the development of an adaptive control algorithm for active suspension systems based on optimal regulation methods. The objective is to design an algorithm which will automatically tune at start-up to changed vehicle conditions and adaptively re-tune to changes in driving conditions (in particular road generated disturbances). The proposed algorithm is a self-tuning regulator based on generalised minimum variance (GMV) control. Simulation results obtained for a 3 degree-of-freedom (DOF) quarter car suspension demonstrate potential benefits of fully adaptive control in automotive suspensions.
TL;DR: In this article, a simulation model is developed to analyze the response of a vehicle with a metal V-belt CVT to a rapid pulley ratio change, and the simulation results are in reasonable agreement with experimental results.
Abstract: SUMMARY In regard to the belt and pulley system of a metal V-belt CVT, the characteristics of the ratio changing speed is obtained by experiments. It is summarized in a practical and simple experimental equation. By using this equation a simulation model is developed to analyze the response of a vehicle with a metal V-belt CVT to a rapid pulley ratio change. The simulation results are in reasonable agreements with experimental results.
TL;DR: In this article, the development and testing of a highvoltage supply unit for modulating the damping force of an electrorheological (ER) fluid damper is described.
Abstract: SUMMARY Controllable dampers using electrorheological (ER) fluids have attracted considerable interest in recent years. They are proposed for use in semi-active suspensions for ground vehicles. The main advantages of ER fluid dampers are their fast response, ease of control, simple construction and low power requirements. This paper describes the development and testing of a high-voltage supply unit for modulating the damping force of an ER fluid damper. Experimental results on the vibration isolation characteristics of an ER fluid damper with different control strategies, obtained using a quarter-car model test rig, are also presented.
TL;DR: In this paper, a numerical method has been developed by which track deformations and the dynamic forces acting between train wheels and rails may be simulated, allowing for calculation of deflections, accelerations and sectional forces in various track components.
Abstract: SUMMARY A numerical method has been developed by which track deformations and the dynamic forces acting between train wheels and rails may be simulated. The method allows for calculation of deflections, accelerations and sectional forces in various track components. The work has resulted in increased possibilities to investigate how parameters such as speed, axle load, wheel base of a bogie, rail corrugations, wheelflats etc influence the dynamic behaviour of track and vehicle components. The computational method may serve as a tool for optimizing the track with reference to life of track components. In order to verify the computational method, a full-scale measurement program was accomplished on the West Coast line in Sweden. Measurements of strains and accelerations in the track were made simultaneously with measurements on the train of rail/wheel contact forces and accelerations. Test results will be presented and compared to calculations. In order to investigate the influence of pad stiffness, the sof...
TL;DR: In this article, the feasibility of improving the braking performance of a commercial vehicle by using an electronic braking system was described, and the proposed control laws can eliminate the effects of a laden condition on the braking distance and increase the degree of deceleration at which wheel lock occurs.
Abstract: SUMMARY This paper describes the feasibility of improving the braking performance of a commercial vehicle by using an electronic braking system. An electronic braking system enables the braking force at each wheel to be independently controlled. Braking force distribution control makes the braking force at each wheel proportional to each wheel's load. Results of computer simulation and vehicle test showed that the proposed control laws can eliminate the effects of a laden condition on the braking distance and can increase the degree of deceleration at which wheel lock occurs, resulting in improved vehicle attitude stability during a critical maneuver.
TL;DR: In this article, the history of one of the wide used theoretical models of the substructure, the Winkler foundation, is described and a discussion of its role in the development is discussed.
Abstract: SUMMARY The paper reminisces the history of one of the wide used theoretical models of the substructure, the Winkler foundation.
TL;DR: In this paper, a mathematical model for the simulation of dynamic behaviour of a train running on a track (eventually supported by a structure) is presented, which takes into account carbody and wheelset deformability, in order to better reproduce measured acceleration and therefore passenger comfort and forces exchanged between wheel and rail.
Abstract: SUMMARY A mathematical model for the simulation of dynamic behaviour of a train running on a track (eventually supported by a structure) is presented. The model takes into account carbody and wheelset deformability, in order to better reproduce measured acceleration and therefore passenger comfort and forces exchanged between wheel and rail. Some results of the comparison with experimental data are presented, and future improvements are outlined.
TL;DR: In this paper, the design concepts for steerable bogies are discussed and a brief historical background is given and the modern design basis generated by the creep theory is summarised with regard to curving performance and dynamic stability of two-and three-axle bogies.
Abstract: SUMMARY This paper deals with the design concepts for steerable bogies. A brief historical background is given and the modern design basis generated by the creep theory is summarised with regard to curving performance and dynamic stability of two- and three-axle bogies. The basic structural elements used for trailing and motorised steerable bogies are illustrated. Experience gained with some recent designs of self-steering and forced-steering bogies is discussed and achievable stability and curving performances are quoted.
TL;DR: In this article, a model based on simple representations of ballast, track and vehicle response is proposed to provide qualitative insights into the physical phenomena involved in a train travelling over a long continuous wave in vertical track profile.
Abstract: SUMMARY Dynamic vehicle/track forces from a train travelling over a long continuous wave in vertical track profile can compress the ballast preferentially in the troughs, thus making the wave worse. This model, built from simple representations of ballast, track and vehicle response, provides qualitative insights into the physical phenomena involved. Predictions are in accordance with expectations from practical experience, and numerical results are within the practical range. The simplifications at present incorporated in the model to offer these qualitative insights are not essential to it, and the approach can be extended to a full quantitative analysis.
TL;DR: In this article, a dynamic settlement model is developed for track settlement behavior under rail traffic. But the model consists of three components: a dynamic vehicle model, a non-linear static model and a mathematical algorithm for predicting trackbed settlement.
Abstract: SUMMARY This paper presents a dynamic settlement model developed the simulation of track settlement behaviour under rail traffic. The model consists of three components: a dynamic vehicle model, a non-linear static model and a mathematical algorithm for predicting trackbed settlement. Simulations of track settlement under various initial geometrical and parametrical conditions are described and simulation results are discussed.
TL;DR: In this paper, the effects of track substructure on the track stiffness, on track roughness, and on the dynamic wheel loads are discussed, and the role of a quasi-static model, GEOTRACK, is briefly discussed and compared with the roles of some dynamic wheel/track models.
Abstract: SUMMARY There are two major issues discussed in this paper. The first is how the track substructure influences some parameters important to the analysis of dynamic wheel/track interaction. This includes the effects of track substructure on the track stiffness, on the track roughness, and on the dynamic wheel loads. The second is how the dynamic wheel loads affect the response and performance of the track substructure. This includes the effects of repeated loads on the ballast degradation, and on the plastic deformation of the ballast and subgrade. Some experimental and analytical results will be presented with regard to these two issues. Additionally, the role of a quasi-static model, GEOTRACK, is briefly discussed and compared with the roles of some dynamic wheel/track models.
TL;DR: In this article, a state variables feedback control system is used to stabilize a car-trailer system at high speed on a straight course with four-wheel steering system and a linear equation of motion.
Abstract: SUMMARY This study aims to stabilize the trailer at high speed. The behavior of passenger cars with four wheel steering system, vehicles with rear wheel steering and of trailer and passenger car are similar. This is regarded as an optimal regulator problem with linear equation of motion, and a state variables feedback control system is adopted. The problem of stability at high speed on a straight course can be solved. Therefore, the passenger car-trailer system can be stabilized. Furthermore, this study indicates the way forward to stabilize a passenger car-trailer system.
TL;DR: In this article, the authors developed a control law for a semi-active suspension for the purpose of ride quality improvement by reproducing the control force of an optimally controlled active suspension while suppressing its damping coefficient variation.
Abstract: SUMMARY The objective of this study is to develop a control law for a semi-active suspension for the purpose of ride quality improvement. The semi-active control law is determined by reproducing the control force of an optimally controlled active suspension while suppressing its damping coefficient variation. The performance index of the optimal control for the active suspension is modified to include frequency-shaping by use of Parseval's theorem, which allows us to de-emphasize the effects of particular variables over specific frequency bands. Through the numerical simulations, it was found that the semi-active suspension may reduce the vertical acceleration of the driver's seat and the sprung mass motions significantly. The road-holding and tire deflections were not affected much.
TL;DR: In this paper, the performance of the preview controller when applied to a real off-road vehicle is simulated using both two degree of freedom quarter and ten degrees of freedom full vehicle models, and the results confirm that preview control reduces vertical acceleration of the body centre of gravity, which results in improved ride quality.
Abstract: SUMMARY The potential performance improvement using preview control for active vehicle suspension was first recognized in the late nineteen sixties. All work done since that time has been based on optimal control theory using simple vehicle models. In this article, the performance of quarter vehicle preview controllers when applied to a real off-road vehicle is simulated using both two degree of freedom quarter and ten degree of freedom full vehicle models. The results, which are compared with non-preview active and conventional passive suspensions, confirm that preview control reduces vertical acceleration of the body centre of gravity, which results in improved ride quality. Further, reductions in pitch and roll motion result from smaller vertical displacements of the vehicle quarters. Coupling between quarters, through the vehicle body, appears to have a smoothing effect on the control. As an alternative to optimal control theory based controllers, a simple ad hoc preview controller based on isolating ...
TL;DR: In this paper, an integrated artificial neural network and linear control theory is introduced for the identification and control of a nonlinear vehicle model structured using a software for multi-body dynamic analysis (ADAMS).
Abstract: SUMMARY Four-wheel-steering (4WS) systems have been studied and developed with remarkable success from the viewpoint of vehicle dynamics. Most of the control methods require a linearized bicycle model of the actual vehicle system which is however strongly influenced by tire nonlinearity. This paper proposes a new method to design the 4WS system taking into account the nonlinear characteristics of tires and suspensions. For this purpose integration of artificial neural network and linear control theory is introduced for the identification and control of a nonlinear vehicle model structured using a software for multi-body dynamic analysis (ADAMS). This model takes into account the nonlinear characteristics of actual vehicles with tires modeled by “magic formula“. The results of computer simulations show that the proposed nonlinear approach is efficient in improving the handling and stability of vehicles.