Modal Stability Control of a Wheeled Heavy Machine

Abstract

Mobile heavy machines as unsprung vehicles exhibit low dissipation ability, hence the ride even at low speeds may give rise to intensive vibration, or even to the galloping effect due to enhanced vertical and angular vibration causing the road wheels to break away from the roadway. As these are mostly low-frequency vibrations, energy dissipation in wheel tires will reduce the vibration intensity in a minor degree only. As a result, the speed of a travel has to be reduced, which adversely affects the cost-efficiency of those machines. Observations of an unsprung machine during its forward ride lead us to formulate the hypothesis of reduced machines stability while it moves in the vertical plane of symmetry. The work [2] confirms the view that the vertical motion of an unsprung heavy machine while it moves forward is implemented under the condition of stability limit, mostly due to stiffness of the dynamic system in the horizontal direction. Mobile machines are dynamic systems, governed by nonlinear and often non-stationary differential equations of motion. Their stability is also dependent on the intensity of acting excitations.