新型离散自适应变结构算法在步进梁控制中的应用

New Algorithm for Discrete Adaptive Variable Structure Used in Walking Beam Movement Control

采用电液伺服控制系统对步进梁的上升驱动液压缸的位移进行精确控制,采用机理法建立系统的离散线性数学模型,综合考虑到步进梁输送钢坯的过程表现出大惯性负载、非线性和变结构的特点,在常规离散趋近律分析的基础上提出了一种新的离散自适应变结构算法。该算法通过双曲正切函数结合自变量的增益因子来实现对切换函数的粗调、细调,并且根据自适应增益的递推规律讨论了系统状态在各个阶段的运动特点,给出了系统的鲁棒稳定性证明。从理论与MATLAB仿真的角度说明了新的算法在变结构消抖和改善系统动态性能方面的优势。在仿真中与指数趋近律和常规自适应趋近律进行了对比,证明了该算法对于要求速度无振荡、位移无超调的步进梁运动控制系统是一种有效的控制策略。

Through applying the electro-hydraulic servo system to accurately control displacement of the walking beam driving hydraulic cylinder,and employing the mechanism analysis method to establish a discrete linear mathematical model for this system,and considering the large inertia load,nonlinearity and the variable structure in the process of walking beam transporting the billet steel as well as analyzing the conventional discrete reaching law,a new algorithm for adaptive discrete variable structure was proposed. This algorithm can achieve both coarse and fine tuning of the switch function through the gain factor which having the hyperbolic tangent function combined with the independent variable,and can display the system's motion characteristics of each stage according to the adaptive gain's recursive rule,including the verification of the system robust stability. From the perspective of theory and MATLAB simulation,the new algorithm's advantages of weakening the shaking in variable structure and improving system dynamic performance can be illustrated. Comparing with both index-reaching law and the conventional adaptive reaching law in the simulation shows that this algorithm is an effective control strategy for the walking beam motion control system which asks for no speed shock and displacement overshoot.