Showing papers in "Vehicle System Dynamics in 1987"
TL;DR: In this paper, a review of the literature relating to the design of automobile suspension systems for ride comfort and control of wheel load variations for frequencies below body structure resonances is reviewed.
Abstract: SUMMARY Based mainly on English language literature, information relating to the design of automobile suspension systems for ride comfort and control of wheel load variations for frequencies below body structure resonances is reviewed. The information is interpreted in the context of vehicles which travel through a wide speed range on roads of markedly differing quality, which do so carrying different loads and which are required to possess good handling qualities. Sections are devoted to describing road surfaces, modelling vehicles and setting up performance criteria, and to passive, active, semi-active and slow-active system types. Methods for deriving active system control laws are outlined. Strengths and weaknesses of the various systems are identified and their relative performance capabilities and equipment requirements are discussed. Attention is given to adaptation of the suspension or control system parameters to changing conditions. Remaining research needs are considered.
344 citations
TL;DR: In this paper, an adaptive control scheme for a two-degree-of-freedom vehicle model with active suspension is proposed, where the performance goal is to minimize the variance of vehicle body acceleration under inequality constraints imposed on either tire or suspension deflection.
Abstract: SUMMARY An adaptive control scheme for a two-degree-of-freedom vehicle model with active suspension is proposed. The performance goal is to minimize the variance of vehicle body acceleration under inequality constraints imposed on the variance of either tire or suspension deflection. An active suspension is adapted to the changes in vehicle velocity and the type of road (or terrain) surface which is assumed to be reconstructable from the accelerometer measurements. The control gain factors are obtained by the iterative method taking advantage of stochastic linear control theory. The performance of the system is evaluated and compared to that of an active system with constant gain factors and a passive system with adjustable parameters.
88 citations
TL;DR: In this paper, the influence of actuator bandwidth on the performance of a class of active suspension systems for automobiles is investigated. And the results indicate that a system with a 3 Hz bandwidth actuator and variable damping will have excellent ride performance qualities over a wide range of road roughness conditions.
Abstract: Using methods established in earlier work, calculations are carried out to reveal the influence of actuator bandwidth on the performance capabilities of a class of active suspension system for automobiles. The suspension consists of an actuator in series with a spring, the combination being in parallel with a passive damper, and the system is modelled as a single wheel station traversing a random road. The results indicate that a system with a 3 Hz bandwidth actuator and variable damping will have excellent ride performance qualities over a wide range of road roughness conditions. Since such a system can be expected to be easily adaptable to the running conditions, to provide good static and dynamic attitude control, to be capable of contributing to good steering control responses and to be inexpensive in terms of capital and energy consumption costs compared with most of the active systems which have previously been discussed, it is suggested that it is a prime candidate for further study and pr...
63 citations
TL;DR: In this paper, a comparative study of the predictions made using computer simulation models of different levels of complexity, of the directional responses of commercial articulated vehicles in steady-state and lane-change maneuvers is presented.
Abstract: SUMMARY This paper presents the results of a comparative study of the predictions, made using computer simulation models of different levels of complexity, of the directional responses of commercial articulated vehicles in steady-state and lane-change maneuvers. The differences in the predictions obtained using various models are examined and are compared with available experimental data. The objective of this study is to compare the capabilities and limitations of various simulation models for predicting the directional behavior of articulated vehicles.
36 citations
TL;DR: In this article, a class of active suspensions is presented which provides near optimum isolation of base motion as well as zero static deflection for force disturbances using a simple type of feedback.
Abstract: SUMMARY A class of active suspensions is presented which provides near optimum isolation of base motion as well as zero static deflection for force disturbances using a simple type of feedback. The load leveling effect is rapid with the system stabilized using isolated mass velocity feedback both for a semi-active damper and for the load leveler. The system can be made energy conservative and fail safe since the system reverts to a reasonable passive isolator if the load leveling effect and even if the active damping effect is switched off. The system could be incorporated in automotive vehicles with some extension of the feedback control to account for several aspects of body motion.
31 citations
TL;DR: In this article, the authors presented the analysis of hydro-pneumatic suspensions using bond graph techniques, different alternatives to their use being presented in this paper, and the high weight and critical conditions of wheel load distribution shown by a crane vehicle supported on a special chassis, suggest hydro pneumatic suspension as most suitable so that they should replace the conventional mechanical types.
Abstract: SUMMARY The high weight and critical conditions of wheel load distribution shown by crane vehicle supported on a special chassis, suggest hydro-pneumatic suspensions as most suitable so that they should replace the conventional mechanical types. The Instituto Tecnologico de Aragon, Zaragoza (Spain) in the collaboration with Industrias Luna S.A., Huesca (Spain) has been working on the analysis of hydro-pneumatic suspensions using bond graph techniques, different alternatives to their use being presented in this paper.
27 citations
TL;DR: In this article, the ADAMS THEORY and APPLICATION is applied to vehicle system dynamics and it is shown that it can be applied to a variety of applications, e.g.
Abstract: (1987). ADAMS THEORY AND APPLICATION. Vehicle System Dynamics: Vol. 16, No. sup1, pp. 121-166.
25 citations
TL;DR: In this paper, it is shown that designs in the hydraulic domain can be transferred to other domains with possible benefits in certain cases, such as transferable dampers from mechanical power to another form of power.
Abstract: Large control forces in vehicle suspension systems or other vibration control systems may often be generated effectively by modulating the dissipation characteristics of an element using only modest control power. Most of the systems proposed in the past have involved hydraulic dampers, but a variety of other resistive elements can also be used. What is required is an efficient transducer from mechanical power to another form of power and a means to modulate a generalized resistor in the energy domain in question. Using bond graphs, it is shown that designs in the hydraulic domain can be transferred to other domains with possible benefits in certain cases.
19 citations
TL;DR: In this paper, a survey on parameter identification techniques for complex vehicle models is presented, in order to cope with the complexity of the model, the information on the system available from the equations of motion has to be included in the identification process.
Abstract: SUMMARY The paper presents a survey on parameter identification techniques for complex vehicle models. In order to cope with the complexity of the model, the information on the system available from the equations of motion has to be included in the identification process. Basic methods for the solution of this problem are shown. The application of the approach is demonstrated by identification of the vertical automobile dynamics. It is concluded that the presented techniques will become more important with increasing applications of theoretical modeling in vehicle system dynamics.
17 citations
TL;DR: In this paper, the principle problems of the new developing scientific field of dynamics of vehicles, tracks and roads are defined and the possibilities are described how to simplify the theoretical models to obtain a simple solution.
Abstract: SUMMARY The principle problems of the new developing scientific field - dynamics of vehicles, tracks and roads - are defined. Basic theoretical models for the analysis of railway and road vehicles, tracks and roads and principle methods of their solution are shown. The dynamic interactions between vehicles and routes are emphasized and several basic equations are given to show the behaviour of their elements. The effect of some parameters, like speed, track or roads irregularities etc. is explained. The possibilities are described how to simplify the theoretical models to obtain a simple solution.
16 citations
TL;DR: In this paper, the authors give an introductory treatment of the handling, stability and vibrating behaviour of two-axle, two-track single unit road vehicles in combined lateral and yaw directions.
Abstract: SUMMARY The paper gives an introductory treatment of the handling, stability and vibrating behaviour of two-axle, two-track single unit road vehicles in combined lateral and yaw directions. The treatment is divided into two chapters. The first deals with the steady-state cornering behaviour and properties of disturbed motions. The chapter starts out with a discussion of tyre force and moment generation properties. The second chapter deals with the vibrations of front wheel assemblies. An extensive discussion is given of the in-plane and out-of-plane tyre dynamic behaviour. Unstable shimmy motions and forced wheel vibrations illustrate the problem area.
TL;DR: In this article, the simulation of a vehicle/pilot system experiencing external disturbances is dealt with, where the car is modeled with two degrees of freedom and the pilot is assumed to respond to the state vector with a time delay.
Abstract: SUMMARY This article deals with the simulation of a vehicle/pilot system experiencing external disturbances. In the simulation, the car is modeled with two degrees of freedom and the pilot is assumed to respond to the state vector with a time delay. When perturbations are introduced, the pilot is expected to drive his car back to the initial state while minimizing a quadratic cost function. With some simplifications for low frequencies responses, the model is then used to simulate the response of different vehicles to an initial step in lateral displacement. The results from the simulations are interpreted in the light of the controllability diagrams.
TL;DR: In this article, a procedure based on covariance analysis and nonlinear programming techniques was developed for the parameter selection of optimum truck suspensions, which can be applied to explore the differences in parameter selection caused by the changes in the frequency content of the road input or by changes in criteria for optimization.
Abstract: SUMMARY The purpose of this paper is to develop a procedure based on covariance analysis and nonlinear programming techniques which can be used for the parameter selection of optimum truck suspensions. The procedure is applied to explore the differences in parameter selection caused by the changes in the frequency content of the road input or by changes in the criteria for optimization. The equations of motion for a tractor-semitrailer truck are cast in state space form. The road excitations are represented by the output of a white noise excited shaping filter taking into consideration the time delays between the different vehicle axles. Shape filters to represent human perception of vibration in both the vertical and longitudinal directions in the time domain are presented and realized in terms of state variables. The suspension parameters of the road-vehicle-human body system are optimized using a direct search algorithm.
TL;DR: In this paper, the authors used the bond graph technique to model the tire as a vehicle component and applied it in the development of symmetrical (vertical, pitch, longitudinal), anti-symmetrical (lateral, yaw) and combined 3D motion models of a motor vehicle.
Abstract: SUMMARY In modelling dynamic vehicle systems the bond graph technique appears to be a powerful tool. The method is illustrated through applications in the development of symmetrical (vertical, pitch, longitudinal), anti-symmetrical (lateral, yaw) and combined 3-dimensional motion models of a motor vehicle. Also, the articulated vehicle has been considered. In the models the tyre plays an important role. Special attention has been paid to bond graph modelling of the tyre as a vehicle component.
TL;DR: In this article, the authors present a method for numerical integration in VANET simulation using a number of different methods, such as: NUMERICAL INTEGRATION METHODS in VEHICLE DYNAMICS SIMULATION.
Abstract: (1987). NUMERICAL INTEGRATION METHODS IN VEHICLE DYNAMICS SIMULATION. Vehicle System Dynamics: Vol. 16, No. sup1, pp. 329-345.
TL;DR: In this article, the response characteristics for body-in-the-seat acceleration, body-to-wheel displacement, dynamic forces, control power and stability are presented for force and displacement inputs based on a simple bounce and roll vehicle model.
Abstract: SUMMARY Response characteristics for body-in-the-seat acceleration, body-to-wheel displacement, dynamic forces, control power and stability are presented in this paper for force and displacement inputs based on a simple bounce and roll vehicle model.
TL;DR: In this article, hot wire anenometry measurements have been made in the wake of a model motorcycle and rider mounted in a windtunnel to determine the frequencies of the weave and wobble modes.
Abstract: SUMMARY Hot wire anenometry measurements have been made in the wake of a model motorcycle and rider mounted in a windtunnel. Only in tests with a topbox present is there clear evidence of eddy shedding. Calculations have been performed on the corresponding full-scale motorcycle to determine the frequencies of the weave and wobble modes. Comparison with the wake frequencies extrapolated to full size show that at speeds of 31-34 m/s they coincide with those of the wobble mode which is found to be efficiently coupled to the aerodynamic excitation.
TL;DR: In this article, the authors show how the equations of motion of a railway car having either a counter-hunting damping device, between wheelset and truck frame, or a direct or crossed stiffness device between front and rear wheelsets are modified.
Abstract: SUMMARY From a classical study of railway stability, the author shows how the equations of motion of a railway-car having: either a counter hunting damping device, between wheelset and truck frame, or a direct or crossed stiffness device between front and rear wheelsets are modified. The critical speed is determined by eigenvalues of matrix A (9,9). From the critical speed variations as a function of: CR typical value of counter hunting damping device, K′ b or K′ b typical value of direct or crossed stiffness, we can say that: the influence of these original systems on the critical speed is more interesting for higher values of equivalent conicity γe, for lower values of γe, the critical speed is high already. the best values of CR of K′ b (or K′ b ) are defined from curves given the critical speed as a function of CR or K′ b (orK′ b ). a crossed stiffness device is more interesting that a direct stiffness device.
TL;DR: In this paper, the transfer function of the bridge-vehicle system is obtained by iteration in the frequency domain instead of the time domain, and the relationship between vehicle speed and the lowest natural frequency of the system is investigated.
Abstract: SUMMARY The paper presents a new method to study the dynamic properties of the bridge-vehicle system. The transfer function of the system is obtained by iteration in the frequency domain instead of the time domain. The relationship between vehicle speed and the lowest natural frequency of the system is investigated and a parametric study of the system stability is made. The varying parameters concerned are the vehicle speed, the ratio of vehicle mass to bridge mass, the ratio of vehicle eigenfrequency to bridge eigenfrequence, and the relative damping of the vehicle and bridge.
TL;DR: In this article, the authors present a Continuous System Simulation Language (CSL) for VANETs, which is used for simulation of vehicle systems in the context of vehicle system dynamics.
Abstract: (1987). CONTINUOUS SYSTEM SIMULATION LANGUAGES. Vehicle System Dynamics: Vol. 16, No. sup1, pp. 347-366.
TL;DR: In this article, the stiffness properties of the elastic suspension of a pair of wheelsets can be characterised by two independent stiffness parameters: a bending stiffness and a shear stiffness, both are related to relative stiffness.
Abstract: SUMMARY The dynamic behaviour of rail vehicles is dominated by vibrational modes containing motions in lateral direction. The ability of a wheelset to perform lateral oscillations when rolling along the track is based on the fact that the wheel treads are profiled. Historically coned wheel treads were used but more recently the application of “worn” or “wear adapted” profiles has become usual. These profiles offer advantages regarding curving behaviour and wear reduction but constitute a non-linearity, complicating lateral dynamics Apart from these geometric aspects, the nature of the oscillations is determined by inertia effects, the elastic properties of the suspension and by creep forces in the contact between wheel and rail. These creep forces constitute a second, and very important, non-linearity The stiffness properties of the elastic suspension of a pair of wheelsets can be characterised by two independent stiffness parameters: a bending stiffness and a shear stiffness, both are related to relative...
TL;DR: In this paper, the authors review the measurements which are necessary to all aspects of vehicle dynamics as applied to rail vehicles, including vehicle parameters, vehicle performance, and vehicle performance validation.
Abstract: SUMMARY This paper reviews the measurements which are necessary to all aspects of vehicle dynamics as applied to rail vehicles. Although an attempt has been made to introduce some reference to measurements made in Europe and America, the detailed discussion has been limited to those techniques employed by British Rail. This has the advantage that the discussion can be first hand and therefore more specific. For convenience the measurements have been collected together under four broad headings. 1. Measurements of rail system data. 2. Measurements of vehicle parameters. 3. Measurements to validate theory and predictions. 4. Measurements of vehicle performance.
TL;DR: In this article, a linear model of a bus was performed and the acceleration, axil forces in the wheel suspension and bending moments in the frame of the bus were measured using the fast Fourier transform technique.
Abstract: SUMMARY Transient analysis of a linear model of a bus was performed. In the experiment the right front wheel of the bus rolled over a bump and one acceleration, two axil forces in the wheel suspension and two bending moments in the frame of the bus were measured. The different parts of the bus were modelled by uniform Rayleigh-Timoshenko beams and rigid bodies. This beam element has a uniformly distributed stiffness, inertia and viscous and/or hysteretic damping along its axis. The loading of the bus due to the bump was in the theoretical analysis modelled by a prescribed transient displacement of the model of the wheel. The fast Fourier transform technique was utilized. Fairly good agreement between calculated and measured values was obtained.
TL;DR: In this article, a two-year research activity on a circular track, which was built in Czechoslovakia for testing the serviceability of different structural types of carriageways.
Abstract: SUMMARY The paper deals with some new results obtained during a two-year research activity on a circular track, which was built in Czechoslovakia for testing the serviceability of different structural types of carriageways. During the testing process the influence on the growing dynamic response of three loading vehicles was also registered, so that experimental verification of the internal dynamic effects in the undercarriage system of loading vehicles according to the Czechoslovak hypothesis of the physical invariant dynamics could be obtained. This contribution presents the basic principles of the invariant theory. Very good agreement of the theoretical calculations with the experimental results on a typical two-mass dynamic system can be stated. For the prediction of serviceability of road pavements an empiricial relation has been derived based on statistical date obtained during a nearly one-year testing period.
TL;DR: In this article, the authors describe how a bond graph model of a multibody system is systematically developed and a systematic notation is introduced to describe a freely moving rigid body is given.
Abstract: SUMMARY In this paper it is described how a bond graph model of a multibody system is systematically developed. To that end a systematic notation is introduced. A bond graph representation of a freely moving rigid body is given. A word bond graph is used to give an overall view of the structure of the mechanical system and to give an outline of the bond graph. The word bond graph is expanded, word by word to obtain a multibond graph of the motorcycle. A motorcycle is modelled to demonstrate the modelling procedure for complex systems. Differential and algebraic equations are derived from the bond graph of the motorcycle and are solved in time. Simulations with the non-linear dynamic model show the motorcycle steering behaviour during a change in roll angle from 0 to 0.5 rad.