THE ROLE OF AN INTEGRAL COMPONENT IN THE CONTROL PROCESS OF AN INDUSTRIAL ROBOT SERVO DRIVE
Authors:
1.
Kazan National Research Technical University named after A.N. Tupolev
2.
Bauman Moscow State Technical University
Type:
Article
Pages:
from 96
to 101
Status:
Published
Received:
24.12.2025
Accepted:
25.12.2025
Published:
25.12.2025
Language:
Russian
Keywords:
MATHEMATICAL MODEL, ASTATIC CONTROL, TRANSFER FUNCTION, STRUCTURAL DIAGRAM, SERVO DRIVE
Abstract (English):
This study focuses on the design of a controller for a robot servo drive. DC motors, which are part of the servo drive of an industrial laser welding system, are often used to provide motion in robotic systems. A servo drive can be any type of mechanical drive with position, speed, and force sensors, as well as a drive control unit, such as an electronic circuit for automatically regulating the required process parameters. Currently, manufacturers install servo drives on each controlled axis of a robot. Automatic regulation of process parameters is achieved using well-known mathematical laws: proportional, integral, and differential. Proportional and differential laws are static, meaning they do not provide the required accuracy, maintaining a static error. The integral component ensures astatic behavior of the system, thereby ensuring accuracy but degrading the transient process quality-stability margins are reduced, and the process becomes oscillatory. The authors previously conducted a study of proportional control of a robot servo drive [1]. This article presents the results of an assessment of the influence of the integral component on the stability and quality of the transient process. The angular velocity of the servo motor shaft was selected as the controlled output parameter. The required process quality indicators were selected for laser welding of metals with a thickness of 0.1 to 10 mm: a control time of no more than 1 second, and the transient process type of damped oscillations. Modeling and calculations were performed using the Matlab mathematical modeling package. The study was conducted in two stages: with and without external influences. A dual-loop structural diagram with position and speed control loops was selected. The integral component was added in stages to the P-controller, first to the position loop, then to the speed loop. Transient processes with the integral component in the position loop turned out to be divergent and were not further investigated. To assess the stability and quality of the transient process, a PI controller was selected in the speed loop. The impact of controller gains on transient response parameters and stability was also assessed. To ensure the specified transient response, the integral gains of the controller were significantly increased, which resulted in increased process oscillation. To compensate for oscillations while maintaining the specified response speed, the proportional gains of the velocity and position loops were increased.
This study focuses on the design of a controller for a robot servo drive. DC motors, which are part of the servo drive of an industrial laser welding system, are often used to provide motion in robotic systems. A servo drive can be any type of mechanical drive with position, speed, and force sensors, as well as a drive control unit, such as an electronic circuit for automatically regulating the required process parameters. Currently, manufacturers install servo drives on each controlled axis of a robot. Automatic regulation of process parameters is achieved using well-known mathematical laws: proportional, integral, and differential. Proportional and differential laws are static, meaning they do not provide the required accuracy, maintaining a static error. The integral component ensures astatic behavior of the system, thereby ensuring accuracy but degrading the transient process quality-stability margins are reduced, and the process becomes oscillatory. The authors previously conducted a study of proportional control of a robot servo drive [1]. This article presents the results of an assessment of the influence of the integral component on the stability and quality of the transient process. The angular velocity of the servo motor shaft was selected as the controlled output parameter. The required process quality indicators were selected for laser welding of metals with a thickness of 0.1 to 10 mm: a control time of no more than 1 second, and the transient process type of damped oscillations. Modeling and calculations were performed using the Matlab mathematical modeling package. The study was conducted in two stages: with and without external influences. A dual-loop structural diagram with position and speed control loops was selected. The integral component was added in stages to the P-controller, first to the position loop, then to the speed loop. Transient processes with the integral component in the position loop turned out to be divergent and were not further investigated. To assess the stability and quality of the transient process, a PI controller was selected in the speed loop. The impact of controller gains on transient response parameters and stability was also assessed. To ensure the specified transient response, the integral gains of the controller were significantly increased, which resulted in increased process oscillation. To compensate for oscillations while maintaining the specified response speed, the proportional gains of the velocity and position loops were increased.
Keywords:
MATHEMATICAL MODEL, ASTATIC CONTROL, TRANSFER FUNCTION, STRUCTURAL DIAGRAM, SERVO DRIVE
MATHEMATICAL MODEL, ASTATIC CONTROL, TRANSFER FUNCTION, STRUCTURAL DIAGRAM, SERVO DRIVE
