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Heavy trucks are becoming more common in use for international transportations, with longer highways and long driving hours contributing corresponding increases in driver's fatigue that is related to accidents. In this paper a detailed procedure is proposed to improve a highway truck seat. A dynamic model of an on-highway truck seat is simulated using Simulink toolbox in MATLAB. The seat suspension including the cushion is mounted on the cab floor of a half truck model and excited by a rapid excitation of step input. The seat suspension system controller is designed to improve the ride quality of the driver. Genetic Algorithms (GA) is used to obtain the coefficients of the control parameters. In addition, model outputs comparison of the proposed design to a conventional passive seat suspension using the maximum overshoot and the root mean square (RMS) values of both, the driver acceleration and the seat suspension working space.

The number of speed humps (sleeping policemen) has seen a global increase in the last decade. This paper addresses the geometric requirements of these humps using Genetic Algorithms optimization techniques to control the speed, stability, and ride feel of the traversing vehicles. The interaction between road hump profile and the modeled vehicles (passenger and a two-axle truck) are studied with a dynamic model. The shape of the proposed profile is described by numbers of amplitudes of harmonic functions. The extreme acceleration of the drivers’ seats of the vehicles traversing the hump is set as multiobjective function for the optimization process, taking into consideration the road-holding ability represented by the tire lift-off speed. The results show that hump geometry can be improved while fulfilling the requirements of speed control and vehicle dynamic responses.

Vibration ride comfort of combat vehicles is essential subject because these vehicles operate at different environments. Improving the comfortability enables the solders to drive for a long time at critical situations with full activity. This paper looks at the ride performance of multi-axles combat vehicles driven at varies speeds over terrain profile. Three configurations of these vehicles, two axles, three axles and four-axles-vehicles, have been studied and compared. The results showed that at a wide range of speeds there is a significant improvement to be gained by using four axles over the three axles and two axles when emphasis is placed on the vehicle body vertical acceleration and dynamic tyre loads.