摘要：The unknown control direction is one of the most open difficult question in nonlinear control theory. A new kind of restricted Nussbaum method is proposed to solve the unknown control direction problem without using high gain feedback. Although High gain has some advantages for improving the dynamic performance of a control system such as it can improve the quickness of the system and it can make the steady state error as small as possible. But now experienced engineers also realized that it causes many problems such as make the system unstable for big signal or high frequency noise. A kind of restricted Nussbaum gain method is firstly proposed to solve the problem. And simulation results show that it has better control effect compared with the traditional Nussbaum gain method. What is worthy pointing out is that the robustness of the Nussbaum gain strategy is improved obviously.
关键词：Nussbaum gain;Unknown control direction;Stability;Uncertainty;Adaptive
