Adaptive iterative learning torque control of electro-hydraulic load simulator

The electro-hydraulic load simulator which can simulate the load executed on the aircraft actuator in the process of flight is an important ground test equipment. The uncertainties of the system including the disturbances caused by the motion of actuator make it challenging to achieve high performance. This study develops an adaptive iterative learning controller for the torque control of electro-hydraulic load simulator utilizing the backstepping method. On the basis of adaptive backstepping control, this controller incorporates iterative learning law to learn unknown nonlinear functions. By utilizing the repetitive characteristic of the test equipment, the iterative learning law sacrifices learning time to achieve enhanced control performance. To handle unknown disturbances, filter error, and learning error, a robust term described by dynamic equations is constructed. The calculation of the derivative of the virtual control law is simplified with a first-order command filter. Simulations with three different controllers are obtained to illustrate the learning ability of the proposed controller.