Showing papers on "Vehicle dynamics published in 1987"

Controller Design for Systems with Unknown Nonlinear Dynamics

Abstract: The control of systems with unknown dynamics is an important issue, particularly in applications where large parameter variations and unexpected disturbances are possible. Several methods have been developed for such cases. These include adaptive control, variable structure control and learning control. This paper first defines this control problem and then proposes a new method - Model Reference Control Using Time Delay (MRC/TD) for nonlinear plants with unknown dynamics. This method will not requireparameter identification, unnecessary discontinuous control or repetative actions. The main feature of the MRC/TD is the direct estimation of the unknown dynamics and the unexpected disturbance. This is accomplished using time delay. This estimation is then used by the controller to cancel both the undesired dynamics and disturbance and to insert the desired dynamics into the plant. The MRC/TD control law for nonlinear plants is presented and the stability analysis and design procedure are given for SISO linear plants. Finally, the validity of MRC/TD is verified through both simulations and experiments.

A vehicle dynamics handbook for single-unit and articulated heavy trucks

Abstract: The handbook provides a compilation of the effects of the mechanical properties of vehicle components and configurations on the braking and steering of heavy trucks. It contains sections describing the braking and steering performance of straight trucks, tractor-semitrailers, truck-full trailers, B-trains, doubles, and triples. Performance signatures and performance measures are presented for driving situations involving constant deceleration braking, low- and high-speed offtracking, steady turning, initiation of curved paths, obstacle evasion (quick lane changes), and braking while turning. The influences of component properties on braking and steering performance, as quantified by computerized analyses and simulations, are illustrated through the use of parameter sensitivity diagrams. The ranges of the mechanical properties used in these sensitivity studies are based upon previously measured data for components that have been employed in heavy trucks.

Bond graphs in vehicle dynamics

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.

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.

Dynamic Simulation of a Vehicle Interacting with Biological and Physical Systems

Abstract: Simulation analysis techniques were applied to study the dynamic response of a vehicle impacting biological and physical system barriers. Computer programs were developed to take into account the environmental factors on ground conditions and vegetation. They were incorporated into the Highway-Vehicle-Object Simulation Model (HVOSM) programs to simulate the interactions between a vehicle and the system barriers. The biophysical barriers were designed to absorb the kinetic energy of the impacting vehicle and to provide a means of preventing fatalities. The simulated results showed that judicious planting of shrubs in median and roadsides would effectively deter the errant vehicle without injury to the operator or damage to the vehicle. The shrub barriers would also reduce traffic noise and headlight glare, providing roadway beautification and environmental safety for natural conservation.

Bifurcation Problems in Railway Vehicle Dynamics.

Abstract: Railway Vehicle Dynamics is a challenging and interesting application of “finite but many-dimensional” nonlinear dynamics. In this article we shall describe only one aspect, namely the investigation of lateral oscillations of railway vehicles moving along a straight, horizontal and “ideal” track. In order to describe the problem adequately the mathematical model consists of from four to order of sixty coupled first-order ordinary differential equations. The number depends of course on the design of the vehicle and the desired accuracy, since there are circumstances where approximations can be made which split the system into some decoupled systems.

Dynamic Measurements in the Research and Development of Rail Vehicles

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.

The preliminary design for high speed ground levitation vehicle—Single side short secondary—Computer aided calculation for the optimal impedance and active force

Abstract: Recently, the research and design of high-speed ground levitation vehicles are very attractive in the modem industrial country. Theoretically, it can't be denied that the cruising speed is higher than 1000 km/hr, but it must be decided by the land size whether the high speed is necessary or not. According to the mechanic strength and dynamics theory, it's impossible that utilizing wheels as speed driving mechanism. This paper has a keypoint to the effect of high speed levitation and utilizes the electromagnetic force which is called as traveling force or levitation force to keep the air gap between rail and vehicle constant. Nowadays, the levitation effect is only built up in theory but in practice which being researched is only the rotary in laboratory-the levitation effect depends on the aid of centrifugal force. The main reason why the research of levitation vehicle has still not succeeded is the weight factor. It's important that how to decrease the weight of vehicle and generated the allowable driving force and levitation force what this paper described above. According to this condition, how to select the material and decided the size etc. of linear motor are also the kernel of this paper. Keeping the flux density constant to calculate all kinds force and find the optimal value of slip. Double side active armature linear motor [13] which has been proposed in the Engineering. Proceeding Vol. 54 No. 11, is the design I, the other one in Vol. 55, No. 11 [14] is the design II. The preliminary design of this paper is the design III.

Trajectory control of nonlinear, time-varying, discrete-time systems using discrete-time sliding control

Abstract: The Deep Submergence Laboratory at the Woods Hole Oceanographic Institution is currently developing supervisory control system methodologies for underwater vehicles and manipulators. An effective low-level control system is a key component in the successful implementation of the high-level supervisory control scheme. The design of this low-level control system for underwater vehicles and manipulators is particularly challenging because of the fluidic environment in which they operate. These environmental effects, when compounded by the uncertain, nonlinear dynamics that characterize such systems, require the use of control techniques beyond traditional methods to ensure reliable and predictable performance. A new discrete-time control methodology, based on continuous-time sliding control concepts, is presented in order to explicitly account for the digital implementation of the controller. The methodology directly addresses the control of systems with nonlinear, time-varying dynamics with uncertain parameters. Quantifiable modeling-performance trade-offs are obtained while accounting for the presence of high-frequency unmodeled system dynamics. The discrete-time sliding control method is demonstrated in simulation and compared to a continuous-time sliding controller.

Dynamics and control of autonomous vehicles

Abstract: Underwater vehicle dynamics are nonlinear and contain substantial uncertainty due to disturbances and modeling error. In this paper, a research effort is outlined that addresses this problem from two perspectives. First, robust nonlinear control techniques are described. These methods directly address problems associated with nonlinearities and model error. Second, the paper summarizes recent advances in hydrodynamic modeling and describes our efforts to integrate these models with the modern nonlinear control techniques described earlier.

An analytical comparison of the dynamic performance of a European heavy vehicle and a generic U.S. heavy vehicle. Final report

Abstract: This report documents a comparative study of the dynamic performance of U.S. and European tractor-semitrailer combinations. The project was accomplished in two phases-- measurement of the suspension and inertial properties of a European tractor and semitrailer supplied by NHTSA, and comparison of the observed properties to those of a typical U.S. tractor-semitrailer in the context of their influence on dynamic performance as determined by simulation with computer models. A number of qualities related to turning behavior were evaluated. The U.S. and European vehicles were both stable and very comparable in turning performance up to 0.3 g lateral acceleration. In the laden condition, the rollover threshold of the European tractor-semitrailer was 9% better than that of the U.S. vehicle due to higher suspension roll stiffness, and a lower center of gravity height. With regard to suspension roll stiffness, the stiffness on the European vehicle was comparable to the highest used on U.S. vehicles (in contrast to the mid-range values assumed for the comparison U.S. vehicle). The lower center of gravity on the European tractor-semitrailer was due to heavier tare weight and lower load capacity. The European tractor-semitrailer exhibited better braking performance than the U.S. vehicle in the conditions evaluated. Higher front-axle braking levels account for the braking advantage. When unladen, the advantage of the European vehicle is largely attributable to use of load-sensing proportioning valves on the tractor and semitrailer, which allow the front brakes to be used more effectively at lightly loaded conditions.

A driving simulator using microprocessors

Abstract: An inexpensive driving simulation system with sufficient fidelity has been developed. The system produces motion cues of four degrees of freedom, visual and auditory cues, and control feel on the steering wheel. This paper describes the features of this newly developed system and gives examples that demonstrate its effectiveness. The motion cues provided in this system are yaw, heave, and lateral and fore/ aft accelerations. The lateral and fore/ aft accelerations are simulated by tilting the simulator compartment. A computer processed road image is given through a crt monitor. The restoring torque of the steering wheel is produced by an electrical servosystem via a coil spring. Cruising sound is given in order to improve speed perception. Since the system uses digital computers, the vehicle characteristics are altered easily by merely rewriting the software. This allows simulation of special vehicle dynamics such as front and rear wheel steering (a).

Development and application of a convolution technique for flying qualities research

Abstract: The mathematical concepts of convolution and superposition are used in a modeling scheme that creates a new capability for studying some modern flying qualities problems. The process computes solutions of very highorder six-degree-of-freedom linear vehicle dynamics on a minicomputer with input/output process times under 10 msec, substituting easily constructed, vehicle step-responses in the time domain for the usual differential equations. Thus, it offers a valuable way to study the flying qualities of nonclassical control responses produced by modern, highly augmented vehicles. Furthermore, standard non-real-time stability and control analysis software can be used to quickly produce real-time minicomputer models, making relatively inexpensive simulator flying qualities studies possible very early in the design/development cycle. A current application to the study of adverse lateral control responses at hover on a large-amplitude research simulator is reviewed.