四轮转向系统非脆弱控制器设计

以四轮转向系统为研究对象，引入H∞控制理论，设计了一种四轮转向系统非脆弱控制器存在的线性矩阵不等式（LMI）条件。通过H∞控制理论有效地抑制外部扰动对系统的干扰，利用Lyapunov函数方法以及矩阵不等式变换技术，将研究系统的控制器存在条件以矩阵不等式的形式给出。与现有的控制器设计方法相比，充分考虑了控制器存在的不确定性摄动，即非脆弱控制问题。最后，通过MATLAB仿真软件对所推导得出的控制器不等式存在条件进行验证，进一步证明了提出方法的有效性。

Design of the four wheel steering system non fragile controller

The contamination proposed in this paper is a defect on the surface of ice cream bar, which is a serious security threat. So it is essential to detect this defect before launched on the market. A detection method of contamination defect on the ice cream bar surface is proposed, which is based on fuzzy rule and absolute neighborhood feature. Firstly, the ice cream bar surface is divided into several sub-regions via the defined adjacent gray level clustering method. Then the alternative contamination regions are extracted from the sub-regions via the defined fuzzy rule. At last, the real contamination regions are recognized via the relationship between absolute neighborhood gray feature and default threshold. The algorithm was tested in the self-built image database SUT-D. The results show that the accuracy of the method proposed in this paper is 97.32 percent, which increases 2.68 percent at least comparing to the other typical algorithms. It indicates that the superiority proposed in this paper, which is of actual use value.