Dynamic envelope and its characteristics under scheduled control law

Abstract

Aircraft loss of control (LOC) inflight is studied as a similar reason for accident. The study for the LOC includes the envelope determination and the LOC protection. And the envelope, which can forecast the advance signal of LOC, is needed to be studied first because of the precondition for protecting the LOC. According to the characteristics of LOC, the dynamic envelope based on the region of attraction theory is proposed to be the envelope for analyzing the problems of LOC. And the reason that the dynamic envelope can be regarded as the LOC envelope represents first. And primary reason is that the stability boundary has the similar performance of the LOC envelope. In addition, the relationship between the dynamic envelope and the scheduled control law are established to illustrate that there is a possibility for the dynamic envelope proposed in an online flight control system. And the characteristics of the dynamic envelope under the scheduled control law are studied in details. And the results show that the influence on the dynamic envelope of the flight altitude is the same as that of the velocity, and they can be combined as the dynamic pressure, which is also important for the scheduled control law. In addition, the dynamic envelope determination for a flight control system can be done at the same time with the control coefficient of the scheduled control law.