Modified design method of an optimal control system for precision motor drive

The paper presents an improved design method of an optimal control system of a linear object with elastic coupling. The proposed method of the optimal control system design implies the selection of desired stability degree instead of the penalty matrixes selection procedure for the quadratic functional. The main idea of the method is the new state matrix utilization, which has its eigenvalues at the specified distance to the right from the eigenvalues of the original state matrix. Thereupon the closed loop state feedback system matrix eigenvalues can be assigned at that specified distance to the left from imaginary axis of the complex plane, in other words the desired stability degree of the system can be achieved. The proposed method of the control algorithm design is demonstrated on the control system of the electric drive with two-mass mechanism (plant). Discrete optimal control system was synthesized. Plant’s characteristic was evaluated from bode plot obtained during identification experiment. Unavailable or immeasurable plants state was estimated by reduced-order observer. Key–Words: Optimal control system, discrete control system, reduced-order observer, two-mass mechanism, state regulator, modal control, degree of stability