基于扰动前馈补偿的HMT换段离合器控制方法

液压机械传动装置（hydro-mechanical transmission, HMT）是一种机-液耦合的强非线性系统，在换段过程中存在外界负载扰动和建模误差等因素影响其换段品质。该研究在分析HMT组成及工作原理的基础上，建立了HMT换段过程动力学模型和线性二次型控制模型，提出一种基于扰动前馈补偿的换段离合器控制方法，借助扰动观测器估计HMT换段过程的总扰动，将扰动补偿增益引入控制器的前馈项，实现扰动前馈补偿，并设计了抑制换段过程扰动的控制器。仿真结果表明，与未采用扰动前馈补偿控制相比，扰动前馈补偿控制的扰动值最大降低了48.9%、冲击度降低了27.8%、滑摩功减少了29.6%、换段时间减少了15.3%。最后通过试验验证了所提方法在快速处理换段过程扰动的同时，可较好地提升HMT的换段品质。研究结果可为液压机械传动装置的工程应用提供参考。

Control method of HMT shifting clutch based on the disturbance feedforward compensation

Hydro-mechanical transmission (HMT) is one type of mechanical-hydraulic stepless transmission. There is a better tradeoff between the stepless speed regulation of hydraulic and efficient speed change of mechanical transmission. Clutch control is closely related to the appropriate timing of engagement and separation, due to the great influence of disturbance on the quality of the shifting process. It is necessary to clarify the shifting clutch for the higher quality of HMT during shifting. However, a strong nonlinear system is coupled with the HMT under modeling error and external load disturbance. In this study, the shifting clutch pressure control was proposed using disturbance feedforward compensation. The dynamical model of shifting and the mathematical model of the clutch in the sliding were also established using the composition and working principle of HMT. The optimal linear-quadratic model was achieved, where the jerk, sliding power, and shifting time were taken as the evaluation indexes during shifting, while the performance index of the quadratic function was the state control variable. The total disturbance during shifting was also estimated to rapidly respond to the disturbance using the first-order disturbance observer. The compensation gain of disturbance was introduced into the feedforward term of the controller, in order to realize the disturbance feedforward compensation. After that, the feedforward compensation gain was obtained, according to the disturbance estimate $hat d $ and compensation coefficient k_d. Then, the optimal controller was designed to suppress the disturbance of the shifting process for the optimization of the quadratic index. The functional weight coefficients were set as q=1, and r=0.1, the equivalent moment of the inertia of the HMT input shaft, clutch C2 driven disc, quantitative motor output shaft, and HMT output shaft were set as 0.02, 0.04, 0.05, and 1 kg·m², respectively, while the equivalent damping coefficients were set as 0.015, 0.2, 0.018, and 0.016 N·m·rad/s, respectively. The co-simulation of HMT during shifting with disturbance was carried out in the AMEsim and Simulink software. The coefficients, k_x, k_h, and k_d of the optimal control variables were calculated by the simulation model in real time. The simulation indicated that the improved control system reduced the maximum disturbance by 48.9%, the jerk by 27.8%, the sliding friction work by 29.6%, and the shifting time by 15.3%, compared with the control without disturbance feedforward compensation. Better control was achieved in the time-varying disturbance of the shifting process. The test of the hydraulic mechanical transmission was also carried out on the test bench, in order to verify the effectiveness of the control system for the better quality of HMT during shifting. Among them, the output load torque and input speed were set as 1 000 N·m, and 1 500 r/min, respectively. Test results show that there was a consistent trend of experiment and simulation, although some error was under control. Consequently, the disturbance feedforward compensation greatly reduced the maximum jerk and shifting time, while suppressing the time-varying disturbance during shifting. The disturbance of the shifting was effectively estimated to better improve the shift quality of HMT under the disturbance working condition. The findings can provide a strong reference for the engineering application of hydraulic mechanical transmission. transmission.