Abstract
Research in the field of tribo-mechatronics has been gaining popularity in recent decades. The objective of the current research is to improve static/dynamics characteristics of hydrostatic bearings. Hydrostatic bearings always work in harsh environmental conditions that effect their performance, and which may even result in their failure. The current research proposes a mathematical model-based system for hydrostatic bearings that helps to improve its static/dynamic characteristics under varying conditions of performance-influencing variables such as temperature, spindle speed, external load, and clearance gap. To achieve these objectives, the capillary restrictors are replaced with servo valves, and a mathematical model is developed along with robust control design systems. The control system consists of feedforward and feedback control techniques that have not been applied before for hydrostatic bearings in the published literature. The feedforward control tries to remove a disturbance before it enters the system while feedback control achieves the objective of disturbance rejection and improves steady-state characteristics. The feedforward control is a trajectory-based controller and the feedback controller is a sliding mode controller with a PID sliding surface. The particle swarm optimization algorithm is used to tune the 6-dimensional vector of the tuning parameters with multi-objective performance criteria. Numerical investigations have been carried out to check the performance of the proposed system under varying conditions of viscosity, clearance gap, external load and the spindle speed. The comparison of our results with the published literature shows the effectiveness of the proposed system.
Highlights
The use of mechatronics to improve tribological performance of hydrostatic bearings is called tribo-mechatronics
Efficiency of hydrostatic bearing is measured in term eccentricity and response time to achieve a new equilibrium position when external load is applied
The current research tries to improve the tribological characteristics of the hydrostatic bearing using a model-based design approach
Summary
The use of mechatronics to improve tribological performance of hydrostatic bearings is called tribo-mechatronics. Several authors have tried to improve the static/dynamic characteristics of hydrostatic bearings using different techniques and methods, and an overview of their achievement can be found in this paragraph. A servo control feedback system is introduced to monitor the fluid film gap and advance control techniques are proposed to improve the dynamic characteristics [13,14], but the deficiency is the lack of experimental validation. Researchers have tried to use the external magnetic field for controlling viscosity of the magnetic fluid, so that the shaft vibrations could be controlled [20,21,22,23,24]. Authors have tried to change the external supply pressure with the help of hydraulic actuator as an active device so that stiffness and the load-carrying capacity could be increased [28,29,30]
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