Optimal control simulation of elliptical shaft center orbit with the hydraulic servo system

Abstract

To bore elliptical hole, the present research proposes hydraulic servo system and the control method to control the shaft center movement orbit. Considering the control difficulty when there are a small number of collocation points, the present research uses optimal control method to solve the control difficulty. Gauss pseudospectral method, which is often used in aerospace field, is applied to obtain relation between shaft center coordinate and load capacity of bearing. And the relation between load capacity and servo valve spool displacement is deduced with flow continuity equation. After the two steps above, the mathematic relation between shaft center coordinate and spool displacement is eventually obtained. The simulation results indicate that compared to the Eulerian control method, optimal control method has better self-adaptation, faster control rate, and higher control accuracy. Even if the starting movement point of shaft center is not on the expected elliptical orbit, or shaft is disturbed by instantaneous external force or dynamical force, the optimal control method still makes the shaft center orbit quickly get close to the expected ellipse. The present research lays theoretical foundation for new boring method of elliptical hole.

A Theoretical Method for Evaluating the Lubrication Performance of the Meshing Pair Profiles in Water Flooded Single Screw Compressors Based on the Micro Deflecting Motion Trajectory

“…Xie defined a new concept of instantaneous whirling speed of axis orbit and studied its new perspective for the vibration analysis of cracked rotors [22]. To bore elliptical hole, Liang and Lu applied Gauss pseudospectral method to obtain the relation between load capacity and servo system, then made the shaft center orbit quickly get close to the designed elliptical hole [23]. To improve the stability of the journal bearing in twin-screw compressors, Wang presented a homogeneous two-phase flow model to calculate bearing axis orbit and analyzed the impact from evaporating temperature and different built-in volume ratio [24].…”