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Showing papers in "Vehicle System Dynamics in 1991"


Journal ArticleDOI
TL;DR: In this article, a review of the generation of shear forces by pneumatic tyres under steady state conditions is presented, in a practical context, through reference to the uses to which models may be put by the vehicle dynamicist and the tyre designer.
Abstract: SUMMARY Modelling of the generation of shear forces by pneumatic tyres under steady state conditions is reviewed. The review is placed in a practical context, through reference to the uses to which models may be put by the vehicle dynamicist and the tyre designer. It will be of interest also to the student of rolling contact problems. The subject is divided into sections, covering physically founded models which require computation for their solution, physically based models which are sufficiently simplified to allow analytical solutions and formula based, empirical models. The classes are more nearly continuous than this strict division would imply, since approximations in obtaining analytical solutions may be made, empirical correction factors may be applied to analytical results and formula based methods may take into account tyre mechanical principles. Such matters are discussed in the relevant sections. Attention is given to the important matter of choosing model parameters to best represent the beha...

367 citations


Journal ArticleDOI
TL;DR: In this article, an optimal adaptive LQG system is compared with a fixed structure nonlinear feedback controller in the context of a simple quarter-vehicle suspension model, and performance comparisons are made, and trends considered under more realistic conditions.
Abstract: A design feature of many computer-controlled suspension systems, is their ability to adapt control law parameters to suit prevailing road conditions. Here, for systems employing high bandwidth actuators and state variable feedback control, the benefits of such adaptation are shown to be at best marginal. An optimal adaptive LQG system is compared with a fixed structure nonlinear feedback controller in the context of a simple quarter-vehicle suspension model. Performance comparisons are made, and trends considered under more realistic conditions. In consequence the overall usefulness of this type of adaptation is called into question.

92 citations


Journal ArticleDOI
TL;DR: In this article, the effects of the ground surface as integrated or filtered white noise on the control laws of an actively suspended vehicle are studied. And the results indicate that the rear body acceleration and rear dynamic tyre load can be reduced by around 20% and 40% respectively with no increase in suspension working space.
Abstract: Based on a mathematical model of an actively suspended vehicle, the effects of the following issues in deriving the control laws are studied: (a)representation of the ground surface as integrated or filtered white noise. (b)cross-correlation between left and right track inputs. (c)wheelbase time delay between front and rear inputs. The third of these issues is shown to be by far the most important. Considerable improvements at the rear suspension can be obtained if the control law includes the information that the rear input is simply a delayed version of the front input. Effectively this provides feedforward terms in the control law for the rear actuator. For the full state feedback case, these improvements are indicated by reductions in the rear body acceleration and rear dynamic tyre load of around 20% and 40% respectively with no increase in suspension working space.

69 citations


Journal ArticleDOI
TL;DR: In this article, the basic functions which suspensions must perform are described and categories of controllable suspensions based on the required amount of control power are defined, and fundamental theoretical and practical limitations in suspension performance are indicated.
Abstract: SUMMARY The basic functions which suspensions must perform are described and categories of controllable suspensions based on the required amount of control power are defined. The kinds of devices which can be used in controllable suspensions are discussed as well as several basic control philosophies. Finally, fundamental theoretical and practical limitations in suspension performance are indicated.

50 citations


Journal ArticleDOI
TL;DR: In this article, an electrohydraulic active vibration control system for the driver's seat for off-road vehicles is presented, based on an analogue model, and the simulation results indicate that the system could effectively absorb vibrations in a chosen frequency band.
Abstract: The paper deals with an electrohydraulic active vibration control system for the driver's seat for off-road vehicles. After a general description of the problem a serial electrohydraulic active vibration control system, working on the compensation principle, is mathematically analyzed. Results of computer simulation, based on an analogue model, indicate, that the system could effectively absorb vibrations in a chosen frequency band. The evaluation method, based on the ISO 7096-82 Standard, is described and the experimental results are presented as well. These indicate, that a 3-fold (or 10 dB) improvement in the vibration absorption, as compared with the passive seat only (based on the weighted rms acceleration values), can be attained. The vibration exposure time can be increased considerably too. The rather large energy consumption is the only drawback.

46 citations


Journal ArticleDOI
TL;DR: In this article, a strongly simplified model of these systems is analyzed by means of the methods of bifurcation theory and analytical and numerical results are shown to characterize the system, including simulation results.
Abstract: Trolleys have wheels which can choose the direction of their rolling. Studying the motion of a wheel like this, we can often find periodic motions (“shimmy”) or even chaotic ones. It has also been experienced that the chaotic motions sometimes disappear quite unexpectedly. A strongly simplified model of these systems is analysed in the paper by means of the methods of bifurcation theory. Analytical and numerical results are shown to characterize the system, including simulation results. Similar behaviour can be found in more complicated systems as well, like the trailers or the nose-gears of aeroplanes. The development of the so-called transient chaotic motion is explained in these systems.

41 citations


Journal ArticleDOI
TL;DR: This report gives a preview to a state-of-the-art paper and a special session which are devoted to the problem of the applicability of multibody computer codes to vehicle system dynamics.
Abstract: SUMMARY This report gives a preview to a state-of-the-art paper and a special session which are devoted to the problem of the applicability of multibody computer codes to vehicle system dynamics. These activities were initiated at the 11th IAVSD Symposium 1989 in Kingston, CAN, followed by a workshop in Herbertov, CSR, and to be reported at the 12th IAVSD Symposium in Lyon, 1991. The concluding documentation will be a special issue of the VSD journal. The status of this report is what has been achieved up to May 1991.

26 citations


Journal ArticleDOI
TL;DR: In this article, the simulation performance and "frequency response" of two concepts in low-bandwidth semi-active suspension control, one that sets a damping force directly and another that sets the damping resistance, are investigated.
Abstract: Active damping has been shown to offer increased suspension performance in terms of vehicle isolation, suspension packaging, and road-tire contact force. It can even approximate the performance of full state feedback control without requiring the difficult measurement of tire deflection. Many semi-active damping strategies have been introduced to approximate the response of active damping with the modulation of passive damping parameters. These strategies have typically required a relatively high bandwidth for actuator response. This paper investigates the simulation performance and “frequency response” of two concepts in low-bandwidth semi-active suspension control, one that sets a damping force directly and another that sets the damping resistance. The electronically controlled bandwidth of these actuators is approximately an order of magnitude less than other semi-active devices; high frequency control is handled mechanically. A quarter-car model is studied with the controlled damping replacin...

23 citations


Journal ArticleDOI
TL;DR: In this article, a MacPherson front wheel suspension and its components are modelled with the finite element method and nonlinearities due to both the geometry and the characteristics of the components (springs, dampers and bushings) are considered.
Abstract: A MacPherson front wheel suspension and its components are modelled with the finite element method. Nonlinearities due to both the geometry and the characteristics of the components (springs, dampers and bushings) are considered. The force due to a given compression/elongation of the spring strut is calculated and compared with experimental results. Kinematical results, change in track width and camber angle, are also shown and compared with experimental results. Good agreement between numerical and experimental results is obtained.

19 citations


Journal ArticleDOI
TL;DR: In this paper, the common basis of the dynamics of active guidance is discussed, and this simple theoretical framework is then followed by a review of work in this field, restricted to wheeled vehicles.
Abstract: SUMMARY In spite of considerable interest in active controls for a wide variety of road and rail vehicles comparatively little work has been carried out on the dynamics of actively guided vehicles in which steering is carried out in response to signals from a controller seeking to follow a given path or track. Drawing from the relevant fields of guided rubber tyred vehicles, rail vehicles and mobile robots the common basis of the dynamics of active guidance is discussed,and this simple theoretical framework is then followed by a review of work in this field. Attention is restricted to wheeled vehicles.

19 citations


Journal ArticleDOI
TL;DR: In this article, a model characterizing human operator behavior in a regulation task is employed to study directional stability, and linear stability is analyzed by the application of the Routh-Hurwitz criterion and stability boundaries separating the stable domain of operation of the driver from the unstable one.
Abstract: The driver of a vehicle has a significant influence on handling and stability of the vehicle. Due to the complex behavior of a human pilot, a driver model is usually neglected when dealing with the problem of vehicle stability. This work focuses on the interaction between the vehicle and the human pilot. A model characterizing human operator behavior in a regulation task is employed to study directional stability. Linear stability is analyzed by the application of the Routh-Hurwitz criterion and stability boundaries separating the stable domain of operation of the driver from the unstable one are constructed. The linear analysis predicts that the only possible instability in a driver/vehicle system is an oscillatory instability with increasing amplitude. It is shown that the addition of kinematic as well as slip angle nonlinearities in the vehicle model can have a stabilizing effect on these oscillations of the combined driver/vehicle system. They may also be responsible for the opposite, namely ...

Journal ArticleDOI
TL;DR: In this paper, a tractrix-based model of a planar multibody vehicle model based on tractrix behavior is proposed to compute low-speed tracking performance of articulated vehicles.
Abstract: Vehicle offtracking behavior at low speeds is closely approximated by a geometric entity called a tractrix. This paper presents differential equations for generalized coordinates of a planar multibody vehicle model based on tractrix behavior. The equations are exact, can be used with any type of input path, are valid for forward and backward movements, and are much simpler than previously published formulations used to compute transient offtracking. The differential equations can be integrated using conventional numerical integration algorithms to obtain plots of the low-speed tracking performance of articulated vehicles. The equations were formulated symbolically by a computer program used to analyze the kinematic and dynamic behavior of multibody systems. Example numerical results are plotted.


Journal ArticleDOI
TL;DR: In this article, the damping performance of a power transmission system with a hydraulic torque converter was established and verified both theoretically and by an experimental test using first-order nonlinear, nonstationary differential equations.
Abstract: In this work three first-order nonlinear, nonstationary differential equations describing a hydraulic torque converter in a power transmission system are used. A linear model is obtained on the basis of these equations. This model is verified both theoretically and by an experimental test. On the basis of the calculations the torsional damping was determined. This permitted the damping performance of a power transmission system with a hydraulic torque converter to be defined and established.


Journal ArticleDOI
TL;DR: The very-high-speed tests carried out by SNCF between the end of 1989 and May 1990, are an extension of the investigations which have been made for many years in order to acquire the control of high speeds as discussed by the authors.
Abstract: SUMMARY The very-high-speed tests carried out by SNCF between the end of 1989 and May 1990, are an extension of the investigations which have been made for many years in order to acquire the control of high speeds. The high-speed run which ended the tests is well known [1], [2],[3]. In order to place the final test campaign in its context, we can recall progression made during the last decade. In February 1981, the maximal speed of 380 km/h was reached with a TGV-PSE1 train set, having the same configuration as the series, but only seven trailers instead of eight. During the following years, until 1986, the pneumatic suspension and the new Y 231 carrying bogies designed for TGV-ATL train sets were developed, with numerous test runnings in the speed range from 300 to 350 km/h, in order to obtain certitudes as regards the stability of the bogies and the appropriate choice of anti-hunting devices for commercial speeds of 270 km/h (LGV-PSE) or 300 km/h (LGV-ATL). These tests allowed the definition of the TGV ...

Journal ArticleDOI
TL;DR: In this article, the dynamics of a vibrator-controlled adaptive damper is simulated on a quarter car model and it is shown that the damper can be constructed totally mechanically without electronics, which provides a practical way for industrial applications.
Abstract: In this paper, the dynamics of a vibrator-controlled adaptive damper is simulated. Its potential in vehicle isolation improvement is demonstrated by a quarter car model. From the results obtained, it is known that after adding a vibrator- controlled flow valve to the conventional hydraulic damper, it is possible to achieve a desired frequency-dependent damping characteristics to provide a large damping at system resonance for the attenuation of the system resonant overshoot, but small damping at higher frequencies to guarantee a good isolation performance. The special feature of this adaptive damper lies in the fact that the damper can be constructed totally mechanically without electronics, which provides a practical way for industrial applications. (A)

Journal ArticleDOI
TL;DR: In this paper, it is shown that there are many possible inverse equation sets and that the eigenvalues of the inverse equations are hard to interpret since they may have little to do with the vehicle parameters.
Abstract: Instead of writing equations which when solved yield the response of a vehicle to an input such as the front wheel steer angle, one can often invert the equations so that a response quantity is specified as an input and a new set of equations is solved yielding the steer angle required as an output. Using these equations one can discover the input steer angle a driver would need to impose in order to accomplish a specific maneuver for various vehicles. It is shown that there are many possible inverse equation sets and that the eigenvalues of the inverse equations are hard to interpret since they may have little to do with the vehicle parameters. The linear single-input single-output case is studied first to fix ideas using a simple example. For the bicycle model vehicle, it is shown that any vehicle may have unstable inverse equations depending upon the response quantity used. Extensions to nonlinear and multiple-input multiple output systems are discussed.

Journal ArticleDOI
TL;DR: The determination of the linearization function for a complex TFE composed of a parallel spring and damper, both having characteristics described by polynosmial functions is described.
Abstract: Output force of a nonlinear two-force-element (TFE) excited by a stationary random process is stationary random as well and is described by its autocorrelation function Dependence of this autocorrelation function on the autocorrelation functions of the excitation process and of its velocity and on their crosscovanance function is indicated by the linearization (describing) function This paper describes the determination of the linearization function for a complex TFE composed of a parallel spring and damper, both having characteristics described by polynosmial functions Knowledge of the linearization function is necessary for carrying out the second order linearization procedure of nonlinear dynamic systems excited by stationary random processes described in ‘1’, ‘2’, ‘3’

Journal ArticleDOI
TL;DR: In this article, the authors describe the receptance properties of non-rigid bodies and their use for the determination of the dynamic system's transfer functions and the output processes' spectral density matrix under stationary random external excitation using stochastical second-order linearization of the nonlinearities.
Abstract: From a vibrational point of view, real vehicles form dynamic systems containing non-rigid bodies and nonlinear two-force elements, often excited by stationary random processes. Their theoretical investigation in a broader frequency range is practically possible in the frequency domain only. In the treatment of nonlinearities second-order stochastical linearization methods can be used advantageously. The amount of necessary computations can be vastly reduced by using known receptance matrices of all bodies in the system in its equations of motion after Fourier transformation. The article describes the receptance properties of non-rigid bodies, their use for the determination of the dynamic system's transfer functions and the determination of the output processes' spectral density matrix under stationary random external excitation using stochastical second-order linearization of the nonlinearities.

Journal ArticleDOI
TL;DR: In this article, the nonlinear attitude dynamics of a twin cycle under output feedback control is studied through bifurcation analysis, and large negative feedback gains are found necessary to assure stability of the twin cycle.
Abstract: The nonlinear attitude dynamics of a twin cycle under output feedback control is studied through bifurcation analysis. Two cases are considered. One assumes no slip and the other assumes small slip. The double zero bifurcation is found to occur in both cases but with different bifurcation sets. Among them heteroclinic orbits are found in both cases and a limit cycle in the second case. The region of feedback gains for stability is obtained. Large negative feedback gains are found necessary to assure stability of the twin cycle. Finally, the tire effect is studied and it causes the distortion of the bifurcation sets.