Modeling, calculation, and analysis of torsional vibration characteristics of the hydrodynamic transmission system in engineering vehicle

According to the typical working conditions of a loader and considering the complexity of the working conditions, the hydrodynamic transmission powertrain system was modeled in this study. Because the hydrodynamic torque converter is a flexible fluid transmission component in the transmission system, this study proposes and establishes equivalent variable damping and equivalent variable stiffness models of the hydrodynamic torque converter. Based on this, a torsional vibration simulation model of the loader with variable damping and stiffness is proposed, and the frequencies and amplitudes of the torsional resonance modes of the transmission system varying with engine speed and hydrodynamic torque converter speed ratio are obtained. It is determined that the variable stiffness of the hydrodynamic torque converter has little effect on the natural frequency of the vehicle, and taking variable damping and stiffness as input, the natural frequency and resonance points of the transmission system can be calculated more accurately. The simulation modeling and calculation approach are experimentally verified, and the simulation results are valid and closer to the real resonance.

Vibration reduction performance of an innovative vehicle seat with a vibration absorber and variable damping cushion

Road driving conditions are complicated, and road unevenness and speed bumps are main sources of vibration that cause the discomfort of passengers in vehicles. The vehicle seat can effectively reduce the system damage and human discomfort caused by this vibration. In this paper, an innovative damping seat that combines a vibration absorber and variable damping cushion is proposed for better vibration reduction performance under different external road excitations. A practical vertical human-seat-vehicle model is established, and uneven road excitation considering trapezoidal speed bumps and rectangular speed bumps is applied to the vertical model. The vibration reduction mechanisms of four different seats (without the absorber and variable damping cushion, with the absorber, with the variable damping cushion and with the new damping seat) are studied by comprehensive time-frequency analysis of the vibration responses. A comparison verifies the improved vibration damping performance of the newly proposed scheme, providing good theoretical guidance for the development of damping seats.

Fuzzy control of a resonant vibration dryer

This thesis presents a fuzzy control method for a vibratory grain dryer. The proposed control methol maintains the resonant condition for a dynamical system having constant linear stiffness, variable mass and variable damping coefficient. The MATLAB simulation results have confirmed that the fuzzy control method based on amplitude measurement is reliable and efficient.

Fuzzy control of a resonant vibration dryer

This thesis presents a fuzzy control method for a vibratory grain dryer. The proposed control methol maintains the resonant condition for a dynamical system having constant linear stiffness, variable mass and variable damping coefficient. The MATLAB simulation results have confirmed that the fuzzy control method based on amplitude measurement is reliable and efficient.

Adaptive Damping Variable Sliding Mode Control for an Electrohydrostatic Actuator

An electrohydrostatic actuator (EHA) is a basic mechanical/hydraulic system with deficiencies including significant nonlinearity and parametric uncertainties. In line with the challenges of designing a high-precision control strategy, an adaptive damping variable sliding mode controller is established, which extends our previous work on EHA control. The proposed controller integrates variable-damping sliding mode control, parametric adaptation, and an extended state observer. The parametric uncertainties are effectively captured and compensated by employing an adaptive control law, while system uncertainties are reduced, and disturbances are estimated and compensated with a fast and stable response. We evaluated the proposed control strategy on a variety of position tracking tasks. The experimental results demonstrate that our controller significantly outperforms the widely used methods in overshoot suppression, settling time, and tracking accuracy.