Digital twin of a servo driver of a servo motor as a first step towards a digital twin of a robot mechanism

Abstract

Digital Twin (DT) offers us to acquire actual system’s critical information and hence, it may be possible to develop and produce more suitable systems in terms of low energy consumption and effectiveness. In this way, responsible consumption and production systems can be designed and the system’s parameters can be tuned via DT. In this study, the model of a servomotor system that is used for industrial purposes is experimentally obtained. This study consists of two steps. In the first step, within the embedded control of the system, position and velocity control loops are deactivated. Then through the servo driver, currents with sinusoidal waveforms at various frequencies are applied to the servomotor. The resultant angular velocity of the motor is monitored and recorded. The amplitude of the current is kept constant during this study. The frequency of the current, however, is increased logarithmically. By using these data, a first-order transfer function (TF) is identified for the motor model. In the second step, all control loops are activated. Consequently, the total servomotor system could be represented in a digital environment. Furthermore, the static friction issue is overcome by using a Coulomb friction model with stiction effect. Finally, several experiments are conducted and then results are compared with the digital model of the servomotor system. The results clearly show that digital model can fairly represent the physical system.