Recess Design and Dynamic Control of an Active Compensating Hydrostatic Bearing

Abstract

This paper describes the optimum design of recess shape for the proposed hydrostatic bearing, and dynamic control of oil film thickness for an active compensating hydrostatic bearing by using a servo valve and a proposed controller. First of all, this study is theoretical study concerning static performance of a hydrostatic bearing having recess of optimal shape parameters. Because of the recess of the traditional hydrostatic bearing only has one oil outlet that is easy to concentrate the pressure of the recess at the outlet, leading to non-uniform pressure distribution. Hence, the objectives of this study are to design a hydrostatic bearing with high load capacity, high stiffness, low flow rate and uniform pressure distribution by using HTGA/Gray optimal approach. In addition, this study integrates servo control technology to compensate the pressure of the bearing with an intelligent nonlinear controller to maintain a constant oil film thickness. However, the hydrostatic bearing is a nonlinear system and is affected by numerous uncertainties; that is, the parameters can be changed by factors, such as temperature, leakage, and disturbance. Therefore, the proposed controller proposes a self-tuning mechanism to modify the output scaling factor, and adds a dead zone compensator to avoid the insensitive area of a servo valve. Finally, the experimental results are used to verify the feasibility and practicality of this study.

Keywords

• hydrostatic bearing
• optimal design
• dynamic control
• self-tuning fuzzy sliding mode controller
• dead zone compensator