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针对一类二自由度欠驱动机械系统,提出了一种基于趋近律法的分级滑模控制策略。该控制策略的基本原理是将一种非线性趋近律引入到系统的控制机制中,该趋近律能够动态地适应被控系统滑动面的变化,可使控制器保持良好性能并削弱系统的抖振。所提控制策略首先将整个系统划分成2个子系统,并对各子系统分别定义第一级滑动面。然后将第一级各滑动面组合成第二级滑动面,并利用第一级各滑动面的等效控制量来构造滑模控制律。基于第二级滑动面和提出的趋近律来求取系统的切换控制量,从而最终获得系统的控制输入量。从理论上分析了闭环系统的稳定性,并通过车摆系统的仿真实验验证了该控制策略的有效性。
For a class of two degree of freedom under-actuated mechanical system, a hierarchical sliding mode control strategy based on the approach of convergence is proposed. The basic principle of this control strategy is to introduce a non-linear convergence law into the control mechanism of the system, which can dynamically adapt to the changes of the sliding surface of the controlled system, maintain the good performance of the controller and weaken the system Chattering. The proposed control strategy first divides the whole system into two sub-systems and defines the first-level sliding surface for each sub-system respectively. Then, the sliding surfaces of the first stage are combined into the second sliding surface and the sliding mode control law is constructed by using the equivalent control amount of each sliding surface of the first stage. Based on the second-level sliding surface and the proposed approach to obtain the system’s switching control of the amount of control, and ultimately access to the system’s control input. The stability of the closed-loop system is theoretically analyzed, and the effectiveness of this control strategy is verified through the simulation of the vehicle pendulum system.