Trim Strategy, Control Model, and Flight Dynamics Characteristics of Canard Rotor/Wing Aircraft in Transition Mode

Abstract

The transition mode of canard rotor/wing (CRW) aircraft is complex and important. During the transition flight, components that generate lift are transferred from one to another, in addition, the redundancy of control system may induce control conflict even plane crash if they don't cooperate well. It is significant to investigate the trim strategy, redundant control, and flight dynamics characteristics of CRW during transition flight. First, aerodynamic forces and moments were calculated by combining the blade element theory, computational fluid dynamics (CFD) and engineering estimation, and the motion equations of CRW in transition mode are established. Next, by analyzing the principle of transition flight, a trim strategy is proposed, and the trim results are credible and reasonable. Then, a control model for solving redundant control is proposed, which can realize simple and effective control during the transition process. Finally, by analyzing the eigenvalues, it is found that the stability of most modes grows with the increase of forwarding flying speed in the transition process, whereas the variation of minority modes is complicated. The results demonstrate the complexity of dynamic characteristics of CRW in transition mode. The trim strategy and control model and the analysis of the dynamic characteristics in the paper can be used for the subsequent control system design and overall optimization design. INDEX TERMS Canard rotor/wing aircraft, transition scheme, model building, flight dynamics, control allocation, dynamics analysis.

A new control strategy of stopped-rotor aircraft based on manipulation model

“…The author has constructed the nonlinear flight dynamics model of SR aircraft in transitional mode (Gao et al , 2019), as shown in equations (1) and (2): where m is the aircraft mass, u , v and W are the components of the flight velocity on the x , y and z axes of the body axis system, q , p and r are the pitch rate, roll rate and yaw rate, respectively, and I x , I y and I z are the moments of inertia. I xz is the product of inertia.…”

“…M x , M y and M z are the resultant moments of the x , y and z axes. The calculation of specific aerodynamic force and torque can refer to Gao (2019).…”

“…In this paper, the dimensional control derivative is selected to represent the control capability of the control system. Then, the dimensional control derivatives Mδheli and Mδfix of the helicopter control system and the fixed-wing control system under multiple trim points in the transition flight of SR aircraft are obtained by using the method of trim and small disturbance linearization proposed in Gao et al (2019), as shown in curve 2 and curve 1, respectively, in Figure 6. Curve 3 is the sum of curve 1 and curve 2, representing the total handling capacity during the transition.…”

“…Some researches on the transition process have been conducted. The performance characteristics of the SR aircraft propulsion system during the transition mode studied by Kong (2005), the dynamics characteristics of SR aircraft in transition mode studied by Gao et al (2019), hovering studied by Gao et al (2017), low-speed forward flight studied by Gao et al (2019) in helicopter mode and dynamics of fixed-wing mode studied by Gao et al (2020). Because of the serious aerodynamic interference in the transition mode of the SR aircraft, which has a greater impact on the stability of the aircraft, He (2013) conducted a dynamic wind tunnel experimental study on the aerodynamic influence of the SR aircraft when the rotor was at slow speed and found that the amplitude of aerodynamic force and moment on the fuselage were rather large and changed dramatically.…”

“…Second, in view of the redundancy of the control system in transition process, a control model is proposed to coordinate the two control systems. Then, based on the nonlinear flight dynamics model of SR aircraft in transition mode established in (Gao et al , 2019), the Takagi-Sugeno (T–S) fuzzy model of the SR aircraft in transition process is proposed and established. Finally, based on the explicit model tracking control and proportional-integral-derivative control, the stability augmentation control system and the outer loop control system are designed, respectively, and the transition flight of the SR aircraft is simulated and verified by Matlab/Simulink, which lays a foundation for the subsequent engineering flight test.…”