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An analytical study of the directional behavior of a tractor-semitrailer vehicle with steered trailer axles is discussed. The model was used to determine the influence of design parameters and steering inputs on the directional behavior of the tractor-semitrailer combination with steered trailer axles. Results obtained from the computer simulation study indicated that the maneuverability of an articulated vehicle with steered trailer axles was improved. The influence of fifth-wheel location with respect to tractor cg on the vehicle directional behavior in a steady-state turning maneuver was also investigated. Fifth-wheel locations near the tractor cg were most effective in reducing the angles of sideslip and articulation.

Recent interest in improving vehicle handling performance has concentrated not only upon achieving maximum acceleration or braking ability of the motor vehicle, but also upon maintenance of high lateral stability during acceleration or braking. This study examines the influence of tire traction and vehicle characteristics on the directional behavior of an automobile undergoing maneuvers requiring combined longitudinal and lateral tire forces. The vehicle model considered in this analysis consists of ten degrees of freedom, including wheel rotational dynamics and steering system characteristics. The equations of motion for the sprung and unsprung masses have been derived using Lagrange's special equations for quasi-coordinates. The analysis includes nonlinear tire traction characteristics which expresses the longitudinal and lateral tire shear force components as analytical functions of several parameters.

A computer simulation model was developed to calculate the tractive performance of agricultural tractors with front and rear mounted three -point hitching arrangements. With a FORTRAN program, the performance parameters for the tractor were simulated and evaluated for four different tractor models. Two hitch positions were chosen for the sensitivity analysis with respect to static weight distribution. Two different traction prediction equations were evaluated.

This paper discusses the computer simulation of a road-vehicle directional response to fixed-control steering inputs using a general purpose simulation language, ACSL. The equations of motion are derived to evaluate the vehicle directional behavior in terms of sideslip angle, yawing velocity gain, and path curvature gain. Computer simulations have been performed to examine the influence of tire lateral stiffnesses, load distribution on front and rear axles, and forward speed on vehicle directional response, in particular on the vehicle turning geometry.

Five analytical mechanics methods to formulate the equations of motion for multilink, articulated machinery systems are discussed, namely the momentum principle, d'Alemberts’ principle, Lagrange's equations. Hamilton's canonical equations, and Kane's method. These methods are examined by means of formulating the equations of motion for a four DOF vehicle system and are discussed from the viewpoint of which method leads most directly to the simplest form of the equations for computer implementation. A brief discussion of general-purpose, large displacement dynamics computer simulation programs for geometrically-constrained, multi-link machinery which utilize these methods is included.

The dynamic longitudinal stability of a skid-steer loader is evaluated by means of a computer simulation methodology. A mathematical model of a loader is formulated in order to evaluate the dynamic stability by means of the linearized eigenvalue problem. A parameter sensitivity analysis is done to evaluate the sensitivity of the dynamic characteristics (i.e. natural frequency and normal modes of vibration) with respect to changes in the design variables.

The static longitudinal stability of a skid-steer loader, as influenced by the kinematic performance bucket linkage and other vehicle operational parameters, is evaluated by means of a mathematical model and computer simulation. With the Integrated Mechanisms Program (IMP), the performance parameters for the bucket linkage configuration are simulated and evaluated for four different loader bucket linkage configurations. With a static force analyses, mathematical relationships are formulated to predict the steady-state longitudinal stability of the loader. These relationships are included in the IMP loader models so that a parameter sensitivity analysis is performed to evaluate the longitudinal stability characteristics.