Authors

Abstract

When a sprayer travels on a ramp or a rough road, the load exerted on each wheel changes. If an unbalanced wheel load is maintained for long periods of time, the wheels may slip, the sprayer’s maneuverability is affected, and a rollover accident may occur. In this study, the air suspension of a self-propelled sprayer chassis was investigated, and the potential load imbalance conditions of the sprayer suspension were analyzed. A mathematical model of the inflation/deflation of the suspension was established based on air nonlinear thermodynamics and vertical dynamics theory and a ¼-scale vertical dynamics model of the sprayer chassis was developed. A control strategy to balance the sprayer’s wheel load was developed. Considering the nonlinear characteristics of the air suspension, a sliding mode variable structure control method was used to balance the wheel load. Simulation experiments were conducted under different working conditions. The simulation results showed that the sliding mode variable structure control provided good control response and precision. The proposed auto load-leveling controller was tested under different working conditions, including different roll and pitch angles and navigating a rough road; the controller successfully changed the load on each spring to ensure that the sprung mass of the suspension was equal and the wheel load was balanced. The results of this study provide reference information for auto load-leveling control of large sprayers.

Abstract in Chinese

喷雾机在凹凸路面或者坡道路面行驶时，导致各车轮负载会发生变化。长时间车轮负载的不平衡，不仅会使车轮出现打滑或失去操纵能力，更会导致侧翻事故的发生。本文以带空气悬架的大型高地隙自走式喷雾机为研究对象，分析喷雾机车轮可能发生载荷不平衡的工况。基于车辆动力学和空气热力学理论，建立了空气悬架充放气数学模型和1/4悬架垂向动力学模型。在此基础上，制定了喷雾机车轮负载平衡控制策略。考虑到空气悬架的非线性特性，采用滑模变结构控制，设计了车轮负载平衡控制器，并以不同工况为例，进行了仿真对比实验。通过仿真实验可以得到，滑模控制对模型参数的变化具有较好的鲁棒性，使其具有良好的控制响应和精度。同时，在侧倾、俯仰和凹凸路面三种工况下，通过本文设计的负载平衡控制器的干预和控制，各弹簧所受载荷也随之变化，最终使得整机左右两侧悬架簧载质量相等，各车轮负载达到平衡状态。通过本文研究，可为大型高地隙自走式喷雾机车轮负载平衡控制提供参考。