Integrated design methodology of ball-screw driven servomechanisms with discrete controllers. Part I: Modelling and performance analysis

Abstract

In order to ensure high-speed and high-precision specifications in ball-screw driven servomechanisms, an integrated design methodology in which driving mechanisms and motion controllers are designed simultaneously is required. As a prior study of the integrated design procedure, it is necessary to obtain not only mathematical models of servomechanisms but also proper formulation of the integrated design problem. In this paper, the feedback and feedforward controllers described in discrete-time domain are incorporated in the motion controller. Design requirements of the servomechanism such as stability, geometric errors, resonance of the driving mechanism, deformation of the structure, actuator saturation and so on are described in detail. Numerical simulations of the servomechanism performance according to design and operating parameters are performed based on the developed mathematical model. An accurate identification process of the driving mechanism is introduced to verify the mathematical subsystem model. Circular motion experiments are conducted to investigate interactions between parameters of the driving mechanism and controller gains, as well as analyze the influence of the interactions on the servomechanism performance. Results of the analysis and experiments let us understand accurate dynamic characteristics of the ball-screw driven servomechanism and render an integrated design possible.