The criterions for absolute stability of direct control systems of lurie type

In this paper, we give necessary and sufficient conditions for absolute stability of several classes of direct control systems, and discuss the absolute stability of the first canonical form of control system. The corresponding results in references [3,5,6] and [7] are improved.This paper is completed under the direct guidance and encouragement of professor Liao Xiaoxin and professor Deng Zhong-qi. The writer especially acknowledges their help.