Study on Qualitative Stability for a Class of Qualitative Control System
一类定性控制系统的稳定性分析

This paper defines qualitative stability for a class of nonlinear plant,and offers a sufficient criterion for qualitative stability of its close loop autonomous system,then the step of constructing the Lyapunov function using variable gradient method is obtained. Finally,for a two order nonlinear plant, a qualitative control which uses all qualitative status as feedback is proposed,and the qualitative stability of close loop control system is discussed.