Study on Control Strategy for Tilt-rotor Aircraft Conversion Procedure

Abstract

This paper studies the control strategy in tilt-rotor aircraft dynamic conversion procedure. A nonlinear flight dynamics model with full flight modes is established. On this basis, a nonlinear optimal control model of dynamic conversion is built by constructing the Bolza form of nonlinear optimal control problem. It contains the limitations and effects of conversion corridor, pilot control, flight attitude, engine rated power, wing stall, and the cooperation between lift and thrust on the procedure of dynamic conversion. An efficient numerical solution method with good convergence is designed to obtain the trajectory and control strategy of dynamic conversion between the modes of helicopter and fixed-wing aircraft. Through the weight parameter analysis, it can be seen that when the subitem of pilot workload is included in the cost function, the displacements of collective stick input as well as the longitudinal stick input are significantly reduced, and the height and pitch attitude change more gently, but the time has been extended. In addition, the pilot workload weight coefficient should not be dominant, otherwise the overly smooth manipulations of collective and longitudinal stick will cause a decrease of height.