Adopting an automatic gear-shifting strategy for agricultural tractors can be an important factor affecting fuel consumption, and a reasonable gear-shifting strategy can effectively improve fuel economy. However, as an important part of the resistance exerted on the tractor–implement combination during tillage, the draught force of the implement strongly influences the driving state of the tractor. The changing characteristics of draught force with work speed largely determine the optimal timing of gear shifting. To realise automatic gear shifting to ensure fuel economy, it is necessary to obtain the varying characteristics of draught force in real time. However, draught force fluctuates is affected by many on-site factors, such as the physical properties of soil, operating speed and the design of the implements. A method is proposed using a recursive least-squares algorithm for the real-time identification of the changing characteristics of draught force. By analysing the forces exerted on the tractor–implement combination and the characteristics of the tractor powertrain, a mathematical model of the tractor–implement combination during field work was established. On this basis, four-parameter gear-shifting schedules were developed for tractor with different types of agricultural implements. The operating conditions were designed based on tractor operating characteristics. The validity and accuracy of the real-time identification method for the changing characteristic of draught force was verified. The designed gear-shifting schedules were proven to realise the automatic gear-shifting function according to the real-time working conditions on the premise of ensuring fuel economy and power performance.

中文翻译：

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基于牵引力特性实时识别的拖拉机节油自动换档策略

农用拖拉机采用自动换挡策略是影响油耗的重要因素，合理的换挡策略可以有效提高燃油经济性。然而，作为耕作过程中拖拉机-机具组合阻力的重要组成部分，机具的牵引力对拖拉机的行驶状态有很大影响。牵引力随工作速度的变化特性在很大程度上决定了换档的最佳时机。为了实现自动换档以保证燃油经济性，需要实时获取牵引力的变化特性。然而，吃水力的波动受许多现场因素的影响，例如土壤的物理性质、运行速度和工具的设计。提出了一种利用递归最小二乘算法实时识别牵引力变化特性的方法。通过分析施加在拖拉机-机具组合上的力和拖拉机动力系统的特性，建立了拖拉机-机具组合野外作业的数学模型。在此基础上，针对不同类型农具的拖拉机开发了四参数换档方案。操作条件是根据拖拉机操作特性设计的。验证了所提出的牵引力变化特性实时识别方法的有效性和准确性。