Repetitive control systems based on IMPACT structure
Miliæ R. Stojiæ
Milan S. Matijeviæ
In many engineering applications there are systems with periodical disturbances as typical characteristics: military radar systems, rotation machines, mechatronics systems for data reading and writing (CD drives), etc. This paper outlines the basic concepts for compensation of arbitrary immeasurable periodical external disturbances and/or for the accurate tracking of periodical reference signals without error in the steady-state. The conventional method based on the application of IMP (Internal Model Principle) is first described briefly and then the more efficient IMPACT (Internal Model Principle and Control Together) controlling structure is proposed, which completely excludes the effects of any periodical disturbance on the steady-state value of controlled variable (system output). Besides the efficient extraction of periodical disturbances, the IMPACT structure enables achieving higher degree of system robustness. The structure design is illustrated by the extraction of periodical load torque disturbance in a speed-controlled electrical drive with DC motor.
Key words: digital control, control algorithm, system robustness, system disturbance, control system, internal model principle.