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Characteristics of Cow's Voices in Time and Frequency Domains for Recognition
Ikeda, Yoshio,Ishii, Y. 한국농업기계학회 2001 Agricultural and Biosystems Engineering Vol.2 No.1
On the assumption that the voices of the cows are produced by the linear prediction filter, we characterized the cows' voices. The order of this filter was determined by examining the voice characteristics both in time and frequency domains. The proposed order of the linear prediction filter is 15 for modeling voice production of the cow. The characteristics of the amplitude envelope of the voice signal was investigated by analyzing the sequence of the short time variance both in time and frequency domains, and the new parameters were defined. One of the coefficients of the linear prediction filter generating the voice signal, the fundamental frequency, the slope of the straight line regressed from the log-log spectra of the short time variance and the coefficients of the linear prediction filter generating the sequence of the short time variance of the voice signal can differentiate the two cows.
A Second-Order Sliding Mode Controller for Active Suspension Systems
Shigehiro Toyama,Fujio Ikeda,Yoshio Sorimachi 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10
This paper presents a second-order sliding mode controller for active suspension systems. The proposed controller, which occurs a limit cycle as the second-order sliding mode, is designed by the integral sliding mode control theory with the twisting algorithm. With the block diagram algebra, the proposed control system can be converted into a nonlinear feedback system consisting of a linear transfer function and a nonlinear element. For the nonlinear system, the describing function method can approximately lead the existence condition for an ideal limit cycle at desired frequency with desired amplitude. Satisfying the existence condition, the proposed controller could almost occur the desired limit cycle in the vicinity of the switching surface, instead of the perfect sliding mode for the conventional sliding mode control theory. As a result, deterioration of the control efforts due to the chattering in high frequency range, such as the ride comfort or the road holding performance, could be suppressed, since the control input could be smooth. An indicator of the robustness against the perturbation of the plant was led from a view of the existence condition in the Nyquist’s plot. Finally, simulation results show the effectiveness of the proposed controller.