Reserch And Development Of The Real-time Control System For The Electro-hydraulic Load Simulator Of The Booster

The booster, which is an actuator helping adjusting the pitch of the helicopter rotor,controls the flight direction and speed, and it need to be test on ground equipment before being equipped to ensure the stability and safety. Electro-hydraulic load simulator, as ground simulation equipment, is used to simulate the law of the booster’s movement when flying and simulate the large acting force with a high and complex frequency on booster that is transformed by aerodynamic force applied on the helicopter rotor. In this paper,a high real-time and high-precision control system for the electro-hydraulic load simulator is proposed, which can be used to simulate the actual working condition of the booster.Firstly, the high real-time control system based on QNX real-time operating system(RTOS) is developed for the loading force with complex and high frequency. The control system control cycle is set to 0.5ms based on the precise timing performance of QNX RTOS;and program a multi-thread control system based on the feature of multi-threaded concurrent in QNX RTOS, furthermore, threads synchronization obtained by the implement of combination of mutex and conditional variables, so that the data shared among threads can be read/ written safely and threads running logic is security, consequently, RT performance and the safety of the control process is clinched.Secondly, aiming at problems including the bad precision due to external loading of the position system of the Electro-Hydraulic loading simulator and the bad performance in loading accuracy of the Electro-Hydraulic loading simulator due to redundant force, robust control theory is introduced briefly at first, and a mathematical model was built, then a constant compensator based on the structural invariance theory is designed and the hybrid compensation method was proposed to enhance the loading accuracy that was composed of a constant compensator which compensates the majority parts of redundant force,then a Disturbance observer (DOB) that eliminate the surplus of it. It’s obtained by applying the structural invariance theory and solving H∞ mixed-sensitivity problem respectively.Then, by the implement of Lab VIEW, the RT monitoring program, which shows the test status and achieves the data sharing,was developed based on the network queue and producer-consumer modelFinally,constant and high frequency force signals’ tracking tests results show that the redundant force was reduced by 65% at least; perturbation test results show the loading simulator’s robustness could be expected, A type of booster loading tests’ results on loading simulator show that RT control system control cycle could be fixed at 50ms; problems that the R/W data error and logical error in multiple threads system have been solved; position tracking precision is up 5.6%,and the hybrid compensation method proved to be valid by the tracking results of the high frequency of force signal.