Adaptive Repetitive Control of Hydraulic Load Simulator With RISE Feedback

Electro-hydraulic load simulator is a typical test-equipment for hardware-in-the-loop simulation, and usually performs periodic tasks, in which the modeling uncertainties will also present some periodicity. With this notification, in this paper, the system model of electro-hydraulic load simulator is established, afterward, all periodic uncertainties are transformed into linear-in-parameters form by applying Fourier series approximation, then an adaptive repetitive scheme with a robust integral of the sign of the error (RISE) feedback is synthesized, in which adaptive repetitive law is designed to handle periodic uncertainties and RISE robust term to attenuate unmodeled disturbances. The developed controller features depending on the desired trajectory rather than the system states, therefore it requires little information of the dynamic system and uncertain nonlinearities, which can apparently restrain the problems from noise pollution. In addition, because the periodic uncertainties are approximated as Fourier series and then compensated, the system performance can be greatly improved when performing periodic tasks. The resulting final control input is continuous while asymptotic tracking performance can be achieved with various uncertainties and disturbances by the proposed controller via Lyapunov stability analysis. In comparison to the other three controllers, the effectiveness and high performance of the proposed control method are validated by the experimental results sufficiently.