基于闭环控制的压路机行走系统改进

Improvement of Roller Running System Based on Closed-loop Control

为了探究闭环控制对于压路机行走速度稳定性的改善作用,采用理论分析与仿真相结合的方法对压路机行走系统进行了分析。根据压路机行走液压系统图及各液压元件的工作特性建立了传递函数模型,并据此推导出了控制电信号及行走负载分别与行走速度响应之间的传递函数关系。结合闭环比例、积分、微分(PID)控制特点对压路机行走系统传递函数模型进行了改进,得到了闭环PID控制下压路机行走系统传递函数模型。在理论推导的基础上,对某12t双钢轮压路机进行了行走试验,将仿真速度曲线与实际速度曲线进行时域及频域对比,并对现有模型进行了仿真分析,探究了闭环PID控制对行走系统特性的影响。研究结果表明:仿真模型能够很好地复现波动负载下压路机实际行走速度的变化规律,在加入PID闭环控制后,在保持速度平均值不变的基础上,压路机行走过程中的速度稳定性有所提升,系统阶跃响应中的超调和振荡现象得到了明显的抑制,稳定时间有所改善,系统的响应准确性更好;将闭环控制用于压路机行走系统中,能够有效地改善压路机平稳作业过程中的速度稳定性,提高压实作业质量。

In order to investigate the improvement of the closed-loop control on the roller speed stability, theoretical analysis and simulation were combined to analyze the running system of the roller. The transfer function model was established by the diagram of hydraulic driving system of double-drum roller and the characteristics of hydraulic components. And transfer function relationships between the control signals and running speed response, running load and running speed response were derived. Then the traditional transfer function model of the roller running system was improved by combining closed-loop PID control characteristics, namely, proportion, integral and differentiation with the result of the present transfer function model under closed- loop control. Running tests on the 12 t double-drum roller were carried out on the basis of the theoretical derivation. After time-domain comparison and frequency-domain comparison of simulated and practical velocity curves, the simulation analysis was done to explore the effect of closed-loop PID control on the characteristics of running system. The results show that the simulation model can present the changing rule of running speed exactly under the load of fluctuation. With the PID control, the velocity stability during the roller running process is improved on the basis of invariability of the average value of the velocity. The super harmonic oscillation in the system step response has been significantly suppressed. The stability time has been improved and the response of the system is more accurate. Thus the closed-loop control applied to roller running system can improve the velocity stability under the process of smooth and steady operation of roller and the compaction quality.