Nonlinear Control Laws for a Wind Tunnel Free-flight Study of a Canard Aircraft

Abstract

This paper presents the study of global nonlinear control law design for a canard aircraft model based on the wind-tunnel free-flight test system which equips Rapid Control Prototype device. We established the flight aerodynamic equations based on data from low-speed wind-tunnel test, and transformed them into state space by using the modern control theory. Firstly, the control law has been divided into outer-loop and inner-loop. For inner loop, nonlinear dynamic inversion (NDI) and incremental nonlinear dynamic inversion (INDI) were applied respectively and conducted comparative analysis. Thrust vectoring control law was synthesized simultaneously based on cascading generalized inverse theory. For outer-loop, the dynamic derivative effects were considered in control matrix. The result of simulation shows that INDI approach is more suitable for this aircraft, for it provides a better linearization of system nonlinearity.