## 1 Introduction  
Morphing aircraft can improve the aerodynamic performance, flexibility of mission execution, and comprehensive performance within the flight envelope, by changing the local or overall shape [1, 2, 3, 4, 5]. It is found that the performance improvement caused by wing deformation increases significantly with the size and deformation scale of the aircraft. However, the aerodynamic and dynamic characteristics of a high-aspect-ratio wing aircraft change drastically during the morphing process. Changes in parameters such as the wingspan, wing area, and moment of inertia will cause the centroid and aerodynamic center to move in a large range, which may affect the stability, maneuverability, and flight performance, such as endurance, rate of climb, and fuel economy of the aircraft, adversely [6, 7, 8, 9]. The relative positions of the centroid and the aerodynamic center are the key factors affecting the stability and maneuverability of an aircraft. Therefore, the first problem to be solved in morphing the aircraft design is balancing the influence of the change in the centroid and the aerodynamic center. At present, measures such as the deflection of the control surface or spread blowing on the wing surface are used to suppress the excessive movement of the aerodynamic center, but this limits the mission adaptability of the morphing aircraft [10; 11]. The large range changes in the centroid and moment of inertia are compensated by the use of lighter materials that meet the deformation requirements, or by the movement of internal fuel and slider [12; 13; 14; 15]. With the progress of bionics research, the coordinate deformation mode of the sweep/ dihedral angle of the arm wing and hand wing parts of large-sized birds provides a new approach for solving the above problems. By observing the wing shape change in raptor-sized birds, such as steppe eagle, swift, gull, albatross, etc., biologists have found that the arm wing (inboard section containing the secondary feathers) moves forward with the wrist joint, while the hand wing (outer section of the wing, consisting of the primary feathers) sweeps to the rear. The dihedral angles of the hand and arm wings also show an opposite change pattern [16; 17; 18; 19; 20; 21; 22; 23]. The multi-section morphing wing can realize the centroid self-trim compensation during the morphing process by the antisymmetric coordinated deformation of the inner and outer wing sections. At present, the research on multi-section morphing wings mainly focuses on aerodynamic characteristics analysis, intelligent deformation structure design, and control system design. [PERSON] et al. [24] have designed a four-bar mechanism to mimic the skeletal structure of a bird's wing. Parameters such as sweep angle, wing area, and wingspan are changed by folding deformation similar to that of the bird's feather stacking. A variable camber airfoil is used to replace the traditional split control surface to realize roll maneuver and landing flight control. [PERSON] et al. [25] have designed a bionic folding wing. The wing structure is made of epoxy webs and polypropylene film. The deformation of the wings can be completed in the plane. [PERSON] et al. [26] have designed a folding wing that can be deployed in the plane through centrifugal acceleration, based on the study of the wing structure of birds and bats. [PERSON] et al. [27] have designed a bionic folding wing that can be folded and deformed in the plane according to the feather structure and deformation law of bird wings. Through theoretical analysis and wind tunnel tests, the aerodynamic characteristics of a bionic wing composed of artificial feathers in different configurations have been studied, and the possibility of using the asymmetric sweep angle change in the outer wing section for roll maneuver control has been discussed. [PERSON] et al. [28] have designed a multi-section variable-sweep unmanned aerial vehicle (UAV) that mimics a seagull wing. The inner and outer wing sections can independently change the sweep angle.