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The ride performance potentials of a prototype torsio-elastic axle suspension for an off-road vehicle were investigated analytically and experimentally. A forestry vehicle was fitted with the prototype suspension at its rear axle to assess its ride performance benefits. Field measurements of ride vibration along the vertical, lateral, fore-aft, roll and pitch axes were performed for the suspended and an unsuspended vehicle, while traversing a forestry terrain. The measured vibration responses of both vehicles were evaluated in terms of unweighted and frequency-weighted rms accelerations and the acceleration spectra, and compared to assess the potential performance benefits of the proposed suspension. The results revealed that the proposed suspension could yield significant reductions in the vibration magnitudes transmitted to the operator's station.

The larger chassis space requirements of hybrid vehicles necessitates considerations of the suspension synthesis with limited lateral space, which may involve complex compromises among performance measures related to vehicle ride and handling. This study investigates the influences of suspension linkage geometry on the kinematic and dynamic responses of the vehicle including the wheel load in order to facilitate synthesis of suspension with constrained lateral space. A kineto-dynamic half-car model is formulated incorporating double wishbone suspensions with tire compliance, although the results are limited to kinematic responses alone. An optimal synthesis of the suspension is presented to attain a compromise among the different kinematic performance measures with considerations of lateral space constraints. In the kineto-dynamic model, the struts comprising linear springs and viscous dampers are introduced as force elements.

In this study, the enhancement of road friendliness of Heavy Goods Vehicle is investigated using two methods to control the resonant forces: (i) Determination of optimal asymmetric force velocity characteristics of the suspension dampers to control the wheel forces corresponding to the resonant modes; (ii) Optimal design of an axle vibration absorber to control the wheel forces corresponding to the unsprung mass resonance mode. An analogy between the dynamic wheel loads and ride quality performance characteristics of heavy vehicles is established through analysis of an in-plane vehicle model. A weighted optimization function comprising the dynamic load coefficient (DLC) and the overall rms vertical acceleration at the driver's location is formulated to determine the design parameters of the damper and absorber for a range of vehicle speeds. The results show that implementation of tuned axle absorbers can lead to reduction in the DLC ranging from 11.5 to 21%.

This paper discusses the optimization of the traction ability of a four wheel vehicle, by reducing the friction between the wheels and the ground required to sustain the motion of the vehicle. As a consequence, this will lead to the safest driving, incurring minimum damage on the surface of the ground. A full optimization includes controlling the longitudinal (tractive) forces and the lateral forces. A control of the vertical reactions (vertical load transfer) is also considered. The control procedure is based on a “disruption motion” that is determined by a geometric-static analysis that does not require solving differential equations. This optimization is a viable basis for computed-torque control of electrically-driven vehicles (e.g. automated guided vehicles, electro-mobiles), and is suitable for the on-line control of any other type of vehicles.

An articulated vehicle suspension comprising a parallel combination of passive energy restoring and dissipative elements and a feedback controlled force generator is analyzed using H2 control synthesis. The active suspension schemes based on limited-state measurements are formulated to minimize a performance measure comprising ride quality, cargo safety, suspension and tire dynamic deflections, and power requirements. The ride quality and the dynamic wheel load performance characteristics of these suspension schemes are compared to those of a vehicle with an ideal active suspension and an “optimum” passive suspension to demonstrate the performance potentials of the proposed limited-measurement-based suspension schemes.

The longitudinal load transfer encountered in a partly-filled ellipsoidal tank truck, subject to a straight-line braking maneuver, is investigated as a function of the location of partition walls, deceleration and the fill level. The response characteristics of the truck equipped with a compartmented tank are evaluated in terms of dynamic load transfer, stopping distance, braking time and time lag between the front and rear axle wheel lock-up. The braking response characteristics are derived as a function of the load shift, and number and location of partition walls. Road tests were performed on an airport fuel truck, equipped with a 3 m long tank with two movable partition walls. The simulation results derived from the test vehicle model are compared to the road test data to demonstrate the validity of the analytical model. The results show good correlation with the measured data acquired under straight-line braking maneuvers performed under different fill levels and initial speeds.

A covariance analysis technique is proposed to derive the optimal suspension parameters of an articulated freight vehicle. A performance criteria comprising vehicle ride response, suspension deflections and tire deflections related to dynamic wheel loads, is formulated for the 9 degrees-of-freedom (DOF) in-plane model of the vehicle. The range of suspension parameters to achieve four different design requirements is identified and a parametric study is performed to make initial parameter selection using the covariance analysis. The optimal suspension parameters are then identified from the results of the study. The study concludes that the proposed technique can yield the optimal solution in a convenient and highly efficient manner.