Analysis of the Servo Drive Dynamics with Allowance for Uncertainties by Methods of the Robust Control Theory

Abstract

Automation of modern technological processes in most cases is carried out by means of an electric drive. Control objects such as industrial robots and manipulators, radar systems and antenna installations, CNC machines and rolling mills, extruders and paper machines often operate in conditions of uncertainty. The parameters of such objects can vary in a certain range according to unknown laws. Unstable parameters include the reduced moments of inertia of electric drives, active resistances and inductances of motors, and gains of amplifiers. External disturbances and noise of phase coordinate sensors also have a negative effect on control objects. The article is devoted to the analysis of the stability and quality of functioning of an electric drive with a brushless motor by methods of the robust control theory, taking into account the uncertainties of the mathematical model of the object and external disturbances. A PID controller is used as a corrective device for the investigated electric drive, the parameters of which are determined using the desired transfer function and the corresponding logarithmic frequency response. The paper obtained the time and frequency characteristics of the electric drive in a given range of unstable parameters. Based on the analysis of the characteristics obtained, conclusions are formulated about the stability and quality of the operation of an electric drive with classical sequential correction. Recommendations on the synthesis of electric drive controllers with uncertainties using the robust control theory of are given.