Aircraft wind tunnel free-flight control method based on a nonlinear control law

The invention discloses an aircraft wind tunnel free-flight control method based on a nonlinear control law. The method comprises the steps of building a flight dynamics equation according to aircrafttest system data of a horizontal wind tunnel; converting the flight dynamics equation into a state space equation; dividing an aircraft control system into an inner ring rotation control loop and anouter ring mass center control loop through a time scale separation theory; for the inner ring rotation control loop, designing the control law by an INDI incremental dynamic inversion method or an NDI dynamic inversion method; for the outer ring mass center control loop, according to wind tunnel dynamic test data, adding dynamic derivative influence terms to design the control law; and controlling the rudder surfaces of an aircraft through the inner ring rotation control loop and the outer ring mass center control loop. According to the method, the system nonlinearity can be effectively counteracted; the interference