Opto-Electro-Mechanical Measurement Method and Apparatus for Control Surface Fold Clearance Based on Controllable Automatic Loading

Fold clearance is a critical factor influencing the bending stiffness and dynamic response of control surface systems. The presence of such clearance introduces significant nonlinearity and hysteresis into the structural stiffness behavior of folding control surfaces, thereby adversely affecting the flight control performance and servoelastic stability of aircraft. Consequently, accurate quantification of fold clearance is essential for predicting its impact on system rigidity, vibrational modes, and overall dynamic characteristics. Traditional clearance measurement techniques, such as manual weight-loading combined with micrometer or dial indicator reading, are prone to substantial errors, low efficiency, and poor repeatability due to human intervention and inherent contact-based limitations. To overcome these drawbacks, this study proposes an integrated opto-electro-mechanical non-contact measurement method based on automated controllable loading. The system employs a high-precision motor-driven actuation mechanism integrated with a real-time force feedback system, which ensures the application of highly precise and repeatable loads in both magnitude and direction. Concurrently, non-contact deformation measurement is achieved through the synergistic use of laser displacement sensors and high-resolution grating scales, effectively eliminating errors induced by physical contact and operator intervention. A dedicated software platform enables automated data acquisition, real-time visualization, and stiffness calculation through embedded algorithms. Experimental validation involving numerous measurements on folding control surface specimens confirms that the proposed system achieves rapid, accurate, and consistent clearance assessment, providing reliable technical support for optimizing the dynamic performance of folding control surface systems.