Based on the structure of a certain type of aviation axial-piston pump's valve plate which adopts a pre-pressurization fluid path(consisting a damping hole,a buffer chamber,and an orifice)to reduce flow ripple,a single-piston model of the aviation axial-piston pump is presented. This single-piston model comprehensively considers fluid compressibility,orifice restriction effect,fluid resistance in the capillary tube,and the leakage flow. Besides,the instantaneous discharge areas used in the single-piston model have been calculated in detail. Based on the single-piston model,a multi-piston pump model has been established according to the simple hydraulic circuit. The single- and multi-piston pump models have been realized by the S-function in Matlab/Simulink. The developed multi-piston pump model has been validated by being compared with the numerical result by computational fluid dynamic(CFD). The effects of the pre-pressurization fluid path on the flow ripple and the instantaneous pressure in the piston chamber have been studied and optimized design recommendations for the aviation axial-piston pump have been given out.
This paper studies a nonlinear robust control algorithm of the electro-hydraulic load simulator(EHLS). The tracking performance of the EHLS is mainly limited by the actuator's motion disturbance, flow nonlinearity, and friction, etc. The developed controller is developed based on the nonlinear motion loading model. The problems of the actuator's disturbance and flow nonlinearity are considered. To address the friction problem, the friction model of the loading motor is identified experimentally. The friction disturbance is compensated using the obtained friction model. Therefore, this paper considers the main three factors comprehensively. The developed algorithm is easy to apply since the controller can be obtained just with one step back-stepping design. The stability of the developed algorithm is proven via Lyapunov analysis. Both co-simulation and experiments are performed to verify the effectiveness of this method.
This paper investigates motion coupling disturbance(the so called surplus torque)in the hardware-in-the-loop(HIL)experiments.The‘‘velocity synchronization scheme’’was proposed by Jiao for an electro-hydraulic load simulator(EHLS)in 2004.In some situations,however,the scheme is limited in the implementation for certain reasons,as is the case when the actuator’s valve signal is not available or it is seriously polluted by noise.To solve these problems,a‘‘dual-loop scheme’’is developed for EHLS.The dual-loop scheme is a combination of a torque loop and a position synchronization loop.The role of the position synchronization loop is to decouple the motion disturbance caused by the actuator system.To verify the feasibility and effectiveness of the proposed scheme,extensive simulations are performed using AMESim.Then,the performance of the developed method is validated by experiments.
