Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
Physical Modeling and Parameters Identification of the MG995 Servomotor
Submission Author:
Luiz Manoel Santos Santana , SP
Co-Authors:
Luiz Manoel Santos Santana, Marcos Maximo, Luiz Carlos Góes
Presenter: Luiz Manoel Santos Santana
doi://10.26678/ABCM.COBEM2021.COB2021-0636
Abstract
Servomotors are a very common electromechanical system. In Academy, there is a large use of Hobby servomotors, because they are low-cost while presenting a reasonable performance for education and research. However, for their use in research, there are two main issues. The first one is the absence of an encoder with position feedback. The second one is little information about the electromechanical parameters in the servomotor's datasheet. Since there is no way to obtain position feedback, an identification experiment cannot be made to obtain the servo's transfer function. The lack of information in the datasheet also hinders an attempt to obtain the transfer function from physical modeling. The main contribution of this work is a methodology to identify the transfer function and the physical parameters of a hobby servo, especially the MG995. This model was chosen due to its large popularity and low-cost. To obtain the position feedback, we needed to solder a wire on the servo's control board and decode the potentiometer's signal. This methodology can be used for other low-cost servomotors with potentiometer position feedback. After getting the position signal we made a system identification experiment to estimate the servo's transfer function. The physical parameters can be obtained by combining data from the datasheets of the MG995 servomotor and the RF-130CH DC motor, physical analyses, and the comparison between the identified transfer function and the physical modeling. To validate the methodology used to obtain the physical parameters we compare a non-linear simulation (with voltage saturation) using the estimated parameters with data collected from experimental step responses of the servo using different amplitudes. The non-linear simulation presents a behavior which closely matches with to the real data obtained from the servomotor.
Keywords
Servomotor, System Identification, Physical Modeling, Parameters Identification
