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Journal Article

Yaw Stability Enhancement of Articulated Commercial Vehicles via Gain-Scheduling Optimal Control Approach

2017-03-28
2017-01-0437
In this paper, a gain-scheduling optimal control approach is proposed to enhance yaw stability of articulated commercial vehicles through active braking of the proper wheel(s). For this purpose, an optimal feedback control is used to design a family of yaw moment controllers considering a broad range of vehicle velocities. The yaw moment controller is designed such that the instantaneous tractor yaw rate and articulation angle responses are forced to track the target values at each specific vehicle velocity. A gain scheduling mechanism is subsequently constructed via interpolations among the controllers. Furthermore, yaw moments derived from the proposed controller are realized by braking torque distribution among the appropriate wheels. The effectiveness of the proposed yaw stability control scheme is evaluated through software-in-the-loop (SIL) co-simulations involving Matlab/Simulink and TruckSim under lane change maneuvers.
Journal Article

Synthesis of a Vehicle Suspension with Constrained Lateral Space using a Roll-plane Kineto-dynamic Model

2010-04-12
2010-01-0641
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.
Journal Article

Property Analysis of an X-Coupled Suspension for Sport Utility Vehicles

2008-04-14
2008-01-1149
The influences of fluidic X-coupling of hydro-pneumatic suspension struts on the various suspension properties are investigated for a sport utility vehicle (SUV). The stiffness and damping properties in the bounce, pitch, roll and warp modes are particularly addressed together with the couplings between the roll, pitch, bounce and warp modes of the vehicle. The proposed X-coupled suspension configuration involves diagonal hydraulic couplings among the different chambers of the four hydro-pneumatic struts. The static and dynamic forces developed by the struts of the unconnected and X-coupled suspensions are formulated using a simple generalized model, which are subsequently used to derive the stiffness and damping properties. The properties of the X-coupled suspension are compared with those of the unconnected suspension configuration, in terms of four fundamental vibration modes, namely bounce, roll, pitch and warp, to illustrate the significant effects of fluidic couplings.
Technical Paper

Pitch Attitude Control and Braking Performance Analysis of Heavy Vehicle with Interconnected Suspensions

2007-04-16
2007-01-1347
This study investigates the performance potentials of hydro-pneumatic suspensions interconnected in the pitch plane of a heavy vehicle. Different configurations of interconnected suspensions comprising pneumatic, hydraulic or hybrid fluidic couplings between the front-and rear-suspension struts are proposed and analyzed. A 7-DOF pitch plane vehicle model is formulated to explore the relative vertical and pitch properties of different suspension configurations, as well as the dynamic responses of the vehicle under braking and road inputs. The mathematical formulations of strut forces due to both the unconnected and pitch-connected suspensions are derived. Relative performance potentials of different configurations are evaluated in terms of sprung mass pitch angle, suspension travel and stopping distance characteristics under different braking inputs and road conditions. The vertical ride quality is further assessed under a range of road roughness excitations and vehicle speeds.
Technical Paper

Optimal Damping Design of Heavy Vehicle with Interconnected Hydro-Pneumatic Suspension

2007-04-16
2007-01-0584
The optimal damping design of roll plane interconnected hydro-pneumatic suspension is investigated, in order to improve vertical ride and road-friendliness of heavy vehicles, while maintaining enhanced roll stability. A nonlinear roll plane vehicle model is developed to study vertical as well as roll dynamics of heavy vehicles. The damping valves and gas chamber are integrated within the same suspension strut unit to realize compact design. The influence of variations in damping valve threshold velocity on relative roll stability is explored, under centrifugal acceleration excitations arising from steady turning and lane change maneuvers, as well as crosswind. The effects of damping valve design parameters on the vertical ride vibration and vehicle-road interaction characteristics are also investigated under a medium rough road input and two different vehicle speeds.
Journal Article

Experimental and Analytical Evaluations of a Torsio-Elastic Suspension for Off-Road Vehicles

2010-04-12
2010-01-0643
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.
Journal Article

Analysis of Ride Vibration Environment of Soil Compactors

2010-10-05
2010-01-2022
The ride dynamics of typical North-American soil compactors were investigated via analytical and experimental methods. A 12-degrees-of-freedom in-plane ride dynamic model of a single-drum compactor was formulated through integrations of the models of various components such as driver seat, cabin, roller drum and drum isolators, chassis and the tires. The analytical model was formulated for the transit mode of operation at a constant forward speed on undeformable surfaces with the roller vibrator off. Field measurements were conducted to characterize the ride vibration environments during the transit mode of operation. The measured data revealed significant magnitudes of whole-body vibration of the operator-station along the vertical, lateral, pitch and roll-axes. The model results revealed reasonably good agreements with ranges of the measured vibration data.
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