Variable universe fuzzy control of the wheel loader semi-active cab suspension with multimode switching shock absorber

The aim of this work is to design a variable universe fuzzy control of a wheel loader semi-active cab suspension with damping multimode switching shock absorber. Considering the cost and reliability, a new type of shock absorber, whose adjustable damping characteristics are achieved by just changing the on–off statuses of two solenoid valves, is applied to the wheel loader cab suspension. The vibration model of the wheel loader, which considers the vibration characteristics of the working device, the four-wheel correlated random road excitation, and the engine vibration excitation simultaneously, is established first. Based on the working principle of the target shock absorber, the damping multi-state switching model is also established to reflect the relationship between the damping coefficients and the on–off statuses of two solenoid valves. Then, a variable universe fuzzy damping control strategy, which can determine the optimal switching sequences of the damping modes according to the cab suspension performance indexes, is designed. Finally, simulation analyses were conducted to verify the effectiveness of the proposed control approach of the wheel loader semi-active cab suspension with multimode switching shock absorber.

Evaluation of Tractor Ride Vibrations by Cab Suspension System

HighlightsTractor ride vibrations were evaluated under various conditions according to type of cab suspension.Ride vibrations were measured on flat and bumpy roads using four tractors with different cab suspension types.Tractors with hydro-pneumatic suspension exhibited smaller ride vibrations than tractors with rubber mounts.Semi-active hydro-pneumatic control resulted in smaller ride vibrations than those resulting from passive control.Abstract. In this study, tractor ride vibrations were evaluated under various conditions according to the type of cab suspension, and the effects of different cab support methods on these ride vibrations were determined. Ride vibrations on flat and bumpy roads were measured using four tractors equipped with different cab suspension types and were analyzed based on ISO Standard 2631-1 for human exposure to whole-body vibration. The ride vibration values were evaluated using the weighted root mean square acceleration and fourth-power vibration dose value. The results confirmed that the tractor equipped with semi-active hydro-pneumatic cab suspension at the two rear positions yielded smaller ride vibrations than the tractors with rubber mounts at all four positions. Vibration reduction effects of up to 53.8% and 67.1% were yielded in the flat road test and bumpy road test, respectively. In addition, among the two tractors with hydro-pneumatic cab suspension systems, ride vibrations were reduced by approximately 7.1% in the tractor that used semi-active control as compared to the tractor that used passive control. Keywords: Hydro-pneumatic cab suspension, Ride vibration, Rubber mount, Whole-body vibration.

Matching, Stability, and Vibration Analysis of Nonlinear Suspension System for Truck Cabs

To improve comfort, a nonlinear suspension system is proposed on the basis of the nonlinear vibration isolation theory and the installation space of the cab suspension system for trucks. This system is suitable for all-floating cabs. For easy matching and design, the static and stability characteristics of the suspension system were analyzed, respectively, and the boundary condition for the stability of the system was given. Moreover, the cab simulation model was established, and the dynamic simulation was conducted. The stability analysis shows that the smaller the vibration excitation of the cab system, the higher its stability is. The dynamic simulation results show that the acceleration of the cab with the nonlinear suspension system is effectively suppressed; the dynamic deflection of the suspension is kept within a certain range, and the design space of the suspension stroke can be effectively utilized. Compared with the traditional linear suspension system, the nonlinear suspension system has better vibration isolation characteristics and can effectively improve ride comfort.