3. Block diagram of the Time Difference Comparison Compensator (TDCC)
in the case (2) used in Dead-Beat Effect of the LQ Optimal Control
The block diagram of TDCC is shown in Fig.1 in the usage of the dead-beat effect of the LQ optimal control. As likely as in the case (1), besides the usual comparison between a desired value and a controlled variable , the time difference comparisons between the reference values and the controlled valuable are composed, where these reference values are obtained to be delayed one after another by the delay element of one sample time, starting from the desired value , in a digital control system with a sample time . The each deviation error obtained by the usual comparison and the time difference comparison is multiplied by the ratios (where ) respectively. Then, the total of these multiplied ones is derived as renewal deviation error which will be inputted to the usual controller for LQ optimal control in a feedback loop. Standing on the TDCC mentioned above, we can design the numbers of these comparisons and the each ratio as to realize a dead-beat effect in the same time to degenerate the peak value of the input variable in the ordinary LQ optimal control. |
Fig.1 The block diagram of TDCC for the realization of dead-beat effect and for the degeneration
of the peak value of input variable in the ordinary LQ optimal control of digital system with a sample time
is the ratio of the direct comparison, and are the ratios of the time difference comparisons.
is expressed as the delay element of one sample time .
4. Application Example of TDCC for to simultaneous effects of both dead-beat and suppression of the peak value of manipulation variable
We introduce the LQ optimal control system with TDCC as shown in Fig.2. In precise, please see reference (1) and/or reference (2) described below [If you click this column, the thesis in PDF files will appear] and references (3)-(6). In Fig.2, indicates the transfer function of a plant in digital expression. In Fig.3, we show indicial responses of both of the controlled variable and the manipulation variable , comparing between two cases with and without TDCC each other. From these result, it is appear that both the dead-beat effect and the suppression effect of the peak value of the manipulation variable reveal simultaneously, and accordingly, it can be said that the characteristics of these responses are improved. On the other hand, the response of a disturbance does not change in the existence of the TDCC. |
Fig.2 Brock diagram of LQ optimal control system with the use of TDCC in digital design |
Fig.3 Simultaneous effects of both dead-beat and suppression of the peak
value of manipulation variable by TDCC in the system shown in Fig.2 Response of disturbance is not influenced by the existence of the TDCC. |
5. References and patents about TDCC in account of
simultaneous effects of a dead-beat control and the degeneration of the peak value of the input variable
(1) Nobuo YAMAMOTO, Michiya MASUDA, Akinori KAWAHARA, Takaya TANABE, and Makoto KIKUCHI: Dead-Beat Effect in LQ Optimal Control with the Use of Time-Difference Comparison Compensation, Research Reports of Ibaraki National College of Technology, No.41, pp.31-38 (2006).
6. Postscript
An invitation mail from the WMSCI 2005 Organizing Committee of Journal of Systemics, Cybernetics and Informatics, to participate in the 9th World Multi-Conference on Systemics, Cybernetics and Informatics, which will take place in Orlando, Florida, USA, from July 10-13, 2005, with respect to our research was arrived at February 23, 2005.
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