| The mechanical environmental test plays an important role in product developing process for providing decision-making information of design modification and optimization. In which the vibration environment test is one important part. In the vibration environment test, the vibration environment and the environment effects endured by the product in actual working conditions can be simulated in a test laboratory in order to test the product’s environmental adaptability and verify its mechanical and electrical performances. The traditional single-axis vibration tests cannot provide enough thrust and cannot simulate a real multidimensional environment, so the multi-axis vibration tests are proposed and widely used. The multi-axis hydraulic vibration testing system not only can simulate a unidimensional or a multidimensional environment, but can meet the vibration testing requirements of high thrust, large displacement, low frequency, etc. Through research of key technologies of the control system in hydraulic vibration tests, some relevant control algorithms for the control system are proposed and designed, and are applied in the system control tests, which gain preferable control effects.Research of the three-variable servo control technologies in hydraulic vibration tests. The servo control plays a basic role in the control of a hydraulic vibration testing system. Aiming at the problems of small damping, low-frequency band, etc. of the hydraulic vibration testing system, a TVC (three-variable control) strategy is researched and designed. And the strategy can achieve an effective correction for the system FRF (frequency response function):(1) the three-variable feedback can effectively extend the system frequency bandwidth and increase the system damping; (2) the three-variable feedforward can further the system frequency by eliminating the poles near to its imaginary axis. Based on the TVC research, a fast parameter-tuning method for the TVC is proposed, which can help to increase the parameter-tuning speed.Identification research of the multi-axis hydraulic vibration testing system. The multi-axis hydraulic vibration testing system is a MIMO (multi-input/multi-output) vibration testing system. Through comparison of the system time-domain modeling and the system frequency-domain modeling, it indicates the frequency-domain modeling does not need to confirm the system specific structure in advance and also has a good stability, which is more suitable for the MIMO system identification. The system identification effects are researched when system disturbances exist, and the research results show that the traditional identification methods of H1, H2, H3, etc. are the biased estimations of the system FRF and the Hv method is an unbiased estimation of the system FRF. As opposed to the traditional estimation methods, the Hv method can effectively eliminate the disturbance influence on the system identification and improve the identification accuracy.Vibration control of the multi-axis hydraulic vibration testing system. In the vibration control process, in order to achieve an effective control of the multi-axis hydraulic vibration testing system and eliminate the nonlinear-factor influences on the system control, the AIC (adaptive inverse control) algorithm is researched, and a frequency-domain filtered-X LMS algorithm is designed and applied in PSD (power spectrum density) replication and TDW (time-domain waveform) replication tests. Meanwhile, through the research of shock vibration tests, in order to simulate the random shock environment endured by the product in its actual working conditions, a random shock control strategy based on the frequency-domain filtered-X LMS algorithm is proposed. At the end, the control processes of the tests are researched and summarized.Control system implementation and tests. Introduce the hardware modules and their functions of the hydraulic servo controller and the vibration controller. Then select a two-exciter/single-axis hydraulic vibration testing system as a testing object to carry out TVC tests, and the test results show that the fast parameter-tuning method can achieve the parameter tuning in TVC process fast and the TVC strategy has a good correction effect on the system FRF. On the other hand, based on the TVC strategy, carry out PSD replication, TDW replication and random shock tests on the testing system based on the frequency-domain filtered-X LMS algorithm, and the test results show that the algorithm has a good control effect on the two-exciter/single-axis hydraulic vibration testing system and the relevant test indicators can fully meet the test requirements, which can further prove the availability and reliability of the control strategy. |
