PID TUNING FOR MULTI-CHANNEL STRUCTURAL FATIGUE TESTING SYSTEM

摘要

A proportion-integration-differentiation (PID) controller is a generic control loop feedback mechanism widely used in multi-channel aircraft structural fatigue test. The PID parameter is obtained by test setup method in which PID is tuned after the test setup is actually performed, so that the tuning period becomes overlong. And the dynamic characteristic of mechanical and hydraulic equipment isn’t considered as a crucial factor to decrease working capability of loading equipment. at the same time, there is coupling effect among channels, which lower control accuracy. For this, based on multi-channel fatigue test of cantilever beam, the coupling mathematics model of testing system is presented and linearized reasonably. The basic procedure of a multi-channel fatigue test is analyzed systematically. The PID parameter of every channel is simulated by stability margin and bandwidth analysis. The dynamic characteristic of hydraulic equipment and test article are analyzed. Finally, a double channel fatigue test of cantilever beam is implemented. The results of simulation and test show that the new method is effective. This method not only has the ability to predict PID parameter rapidly and the dynamic characteristic of test equipment, but it can also reduce effectively the control errors.