# Analysis of Motion Characteristics of Bionic Morphing Wing Based on Sarrus Linkages
## 2 Materials and Methods
### Prototype Folding and Unfolding Experiment  
The morphing wing of the transmedia aircraft is mainly composed of fuselage connecting drive module, wing body, and folding connecting device based on a Sarrus structure. The variation control technology of the morphing wing designed in this paper adopted the electronic control technology, mainly using the control of the electric steering engine, to complete the variation of the wing action. The steering engine is a position servo driver which can continuously change the rotation angle in the process of motion and keep the same motion angle over a certain period of time. It can control the folding angle of the morphing wing.  
The fuselage-connecting drive module includes a connecting base, driving-steering engine, and steering engine hinge. Its main function is to connect the wing part with the fuselage and connect the driving-steering engine to this part. The connecting base also bears the weight of the entire wing, so it is strong enough to resist the static bending moment of gravity.  
The driving-steering engine is installed on the connecting base. The driving-steering engine is connected with the inner wing connecting rod through the steering actuator hinge, and the output end of the driving-steering engine is connected with the steering engine hinge. The connecting base and steering engine hinge are 3D-printed with nylon material. Futaba S9001 was selected as the driving model of the steering engine. The basic parameters of the steering engine are shown in Table 2:  
Figure 8: Model of unfolded state of morphing wing motion simulation.  
Figure 9: Comparison of simulation model and prototype folded states: (**a**) folded 45\({}^{\circ}\) state; (**b**) folded 90\({}^{\circ}\) state.  
The folding connecting device based on the Sarrus structure is the core driving skeleton of the morphing wing designed in this paper and is mainly composed of a wing connecting rod, bottom connecting rod, outer frame, and related connecting pieces (tube clamp, connecting hinge).  
The wing carbon tube and the bottom connecting rod are made of carbon tubes according to the design size. The outer frame and the tube clamp are made of nylon 3D printing material. The hinge part connecting the hinge is made of PLA 3D printing material, and the hinge shaft connecting the hinge is replaced by bolts of appropriate size.  
In order to verify the feasibility of this morphing wing folding scheme, the author made an experimental prototype according to the size of the simulation model, and the key dimensions and materials of its components are shown in Table 3.  
The attitude sensor was placed at the centroid position of the inner wing connecting rod, and the steering engine was energized to control the angle rotation of the inner wing. The data of time, folding angle, velocity, and acceleration of inner wing movement were recorded in real time by PC software so as to complete the folding-unfolding experiment of the morphing wing. The prototype model and experimental process are shown in Figure 10, and the experimental results were analyzed.