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Digital Redesign of Continuous Time Controller
by Multirate Sampling and High Order Holds
Yuping Gu, Masayoshi Tomizuka and Josep Tornero
Abstract
This paper presents the digital redesign of continuous time controller when the measurement sampling period is
relatively large and standard discretization methods are most likely not able to provide a suitable digital controller
from either stability or performance point of view. An analysis tool is provided to improve the performance of
digital control systems by the following two measures: 1) update the controller output N times faster than the
measurement sampling frequency, and 2) utilize past sampled outputs to predict the evolution of the output error
between two consecutive sampling instances. The analysis tool is developed by regarding the overall system as a
multirate sampled data system. An illustrative example is given to show the utilization of the developed analysis
tool.
Keywords:
multi-rate control, digital control.
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