## 1 Introduction  
As the complexity of aircraft applications in the aerospace field continues to grow, modern aircraft are required to operate across broader flight envelopes and speed ranges. Traditional fixed-geometry aircraft are unable to adapt to such variable flight environments and mission requirements, thereby limiting their performance under specific conditions [1, 2]. In contrast, morphing aircraft can adjust their configurations based on mission demands, environmental conditions, and their own operational states, allowing them to adapt to diverse flight scenarios. To date, various morphing aircraft have entered service and demonstrated excellent adaptability [3, 4, 5, 6, 7]. Morphing wings are a critical research area within the broader domain of morphing aircraft. After their design is completed, these wings must undergo a series of tests to validate their performance, especially in terms of failure modes, operational reliability, and safety under different flight conditions. Unlike traditional fixed-wing loading methods, morphing wings can change their aerodynamic shape, necessitating continuous loading during ground testing to match their deformation process. Therefore, the loading system must provide servo-controlled loading synchronized with the wing's deformation to ensure the accuracy of the test results [8; 9; 10]. Currently, research on servo-controlled loading devices for morphing wings remains limited. [PERSON] et al. designed an experimental setup for folding wing deployment, simulating lift loading during the deployment process using cylinders and bearing components. Their study found that lift had a significant impact on the deployment time of folding wings [11; 12]. Beyond this, most related studies focus on servo-controlled loading devices for slat and flap morphing. For instance, [PERSON] et al. analyzed the advantages and disadvantages of three servo-loading techniques, namely synthetic loading, pivot loading, and multi-degree-of-freedom separated loading, recommending methods based on specific objectives [13]. [PERSON] et al. proposed a dual-actuator servo-controlled loading technique with sliding carriages, addressing the challenge of changing normal load directions during the deflection of movable wing surfaces [14]. [PERSON] et al. utilized finite element analysis to divide wing deformation into multiple flight points, employing a dual-actuator servo system to maintain a high degree of perpendicularity between the loading force and wing surface during large deformations [15]. [PERSON] et al. designed a separated servo-controlled loading device that was successfully applied in flap fatigue testing, achieving precise control of the load magnitude and direction [16]. However, most existing studies have targeted simpler deformation mechanisms with limited ranges, such as those in slats and flaps. In contrast, morphing wings exhibit large and complex deformations, making traditional static test methods inadequate for accurately simulating their actual deformation processes. To better simulate aerodynamic loading, [PERSON] highlighted common methods for transferring aerodynamic grid loads to finite element structural grids, including three-point, four-point, and multi-point methods [17]. [PERSON] [18] provided a detailed implementation process for the multi-point method and applied it to the aerodynamic load distribution of an aircraft's horizontal tail. [PERSON] et al. [19] compared the three-point, four-point, and multi-point methods through case studies, concluding that these approaches effectively transfer aerodynamic grid loads to structural grids. When structural grid nodes coincide with predefined loading points, aerodynamic grid loads can be equivalently transferred to these points. While these methods work well for fixed-wing load equivalency, they are not suitable for morphing wings, where surface areas change dynamically during deformation.