Research on Automatic Attitude Control Technology of Six-Degree-of-Freedom Displacement Compensation for Full-Scale Aircraft Static Test

Abstract A novel closed-loop control principle was proposed for precisely controlling the attitude of full-scale aircraft during static test under large deformation. The test system was developed by integrating a displacement acquisition system, an industrial computer platform, a coordinated control system and hydraulic actuators. The displacement acquisition system was employed to facilitate the real-time sensing of the aircraft attitude changes. This was subsequently analyzed by computers to calculate attitude errors, based on which the compensation values were calculated for attitude correction. The correction was converted into voltage signals through an in-house program pre-integrated into the industrial computer platform. Finally, the MTS coordinated control system generates new control parameters based on the voltage signals, enabling a real-time adjustment on the movement of hydraulic actuators, which modifies the aircraft attitude. A device was developed for simulating the deformation characteristics of aircrafts under large deformation. A six-degree-of-freedom restraint system has been installed on the device according to the principle. Experiments were conducted to verify the capability of the approach for precisely controlling the aircraft attitude under various deformation states. Results showed that the aircraft attitudes were all restored to a value close to the theoretical attitude via displacement compensation scheme proposed, with the translational error less than ± 2 mm and the rotational error less than ± 0.02°. Whilst these errors were successfully reduced by applying the compensation algorithm during loading, they cannot be completely eliminated due to the influence of measurement and control errors.