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.

Combined effect of recess shape and fluid film thickness on the performance characteristics of hydrostatic guideways

“…The ratio of recess area to land area is kept constant, for calculating the recess dimension of shapes other than rectangular recess shape. 5 This approach was adopted for understanding the relation between load capacity and recess pressure, for constant recess area. 4 In calculation, the rectangular pad area is taken as reference and the geometric parameters of other recess shapes are calculated by equating with 2970 mm 2 (rectangular pad area) as shown in Table 1.…”

“…Orifice and capillary type compensators are commonly used in hydrostatic components. 4 Shih and Shie 5 analyzed the effect of restrictor geometric parameters on the load bearing capacity for both orifice and capillary type compensator. Hydrostatic guideways are connected to flow controller to vary the fluid flow in accordance with the load acting (i.e.)…”

An active control for hydrostatic journal bearing using optimization algorithms

“…These constant resistance passive devices can not improve the performance of mechanical design of hydrostatic bearing. So, active pressure regulating methods are getting popularity these days, for example, in Shih and Shie (2013) some servo control techniques are used to control fluid film thickness in real time. This paper proposes Nelder Mead based fractional order PID controller (NM-FOPID) and particle swarm-based fractional order PID control (PSO-FOPID) for servo-controlled hydrostatic bearing system.…”