2016 Volume 10 Issue 4 Pages JAMDSM0061
In the sampled-data positioning control system of mechatronic products, it is hard to analyze the effect of mechanical resonances above the Nyquist frequency after the control systems were assembled. However, unexpected variations of mechanical characteristics often happen in actual mechatronic systems. To solve such a problem, this paper proposed two analysis methods with measurable open-loop characteristics in single-input/single-output (SISO) sampled-data positioning control systems. These methods use frequency responses of the controlled object and the digital controller for calculating the measurable open-loop characteristics without complicated calculations involving state-space representations of a controlled object, or integrations of matrix exponentials. The proposed methods indicate that we can analyze the performance of the sampled-data control system beyond the Nyquist frequency by using these measurable open-loop characteristics. To show the validity of the proposed methods, this study conducted simulation analyses on the sampled-data positioning control system of a magnetic head-positioning control system in a hard disk drive. These results show that proposed open-loop characteristics are good approximated solutions in order to analyze the control system performance of the sampled-data positioning control system beyond the Nyquist frequency.
