23,086 research outputs found
AN OBSERVER DESIGN FOR TIME-DELAY CONTROL AND ITS APPLICATION TO DC SERVO MOTOR
No full textThis paper addresses the estimation problem of states and their derivatives for the Time Delay Control (TDC), a robust control technique for nonlinear systems. To this end, an observer design method is presented. Then, in simulations, the controller/observer has been applied to a nonlinear plant, with satisfactory results. Finally, experiments were undertaken on a DC servo motor subject to substantial inertia variations and external disturbances. The results showed that the controller/observer performs quite robustly under those variations and disturbances, and is much less sensitive to sensor noise than the controller using numerical differentiations
Vibration control of a telescopic handler using time delay control and commandless input shaping technique
No full textA telescopic handler is a type of construction machinery used for the loading, transporting and unloading of various forms of cargo. To increase its productivity, the boom of the telescopic handler should be operated at high-speed mode without any occurrence of vibration. Residual vibration, however, in the boom often arises when lifting cargo to higher positions. To solve this problem associated with the occurrence of vibration, we applied time delay control and commandless input shaping technique, which is a modification-based on the concept of Input Shaping Technique. We confirmed their effectiveness through experiments. (C) 2003 Elsevier Ltd. All rights reserved
On improving time-delay control under certain hard nonlinearities
No full textTime-delay control (TDC), owing to its simplicity and unusual performance against parameter variations and disturbances, has been noted and recognized as a promising technique. We have observed, however, that in the presence of so-called hard nonlinearity such as saturation or static friction, TDC reveals some problems commonly found in other methods like PID control or disturbance observer. Specifically, when the system has a saturation limit, TDC shows the windup phenomenon; when static friction and Stribeck effect are dominant, TDC reveals the stick-slip phenomenon. In this paper, we have reported these phenomena associated with TDC, presented their causes, and proposed their remedies. Specifically, through analysis, simulation, and experiment, we have shown that both the phenomena cause serious degradations in control performance; that they result from a common cause, the inherent integral effect in TDC; and that the proposed compensators are effective enough to handle the phenomena. In addition to their effectiveness, the proposed compensators have unusual simplicity and efficiency that matches the positive attributes of the original TDC. (C) 2002 Elsevier Science Ltd. All rights reserved
Lactococus garvieae infection of cultured rainbow trout, Oncorhynchus mykiss , in Taiwan and associated biophysical characteristics and histopathology.
No full textEffect of castration on hair re-growth in Pomeranians with hair cycle arrest (Alopecia X)
No full textDiabetic dogs with concurrent hyperadrenocorticism: a retrospective study of 11 cases during 1995-1999
No full textA reduced order time-delay control for highly simplified brushless DC motor
No full textA reduced order time-delay control is derived and applied to the position control of a brushless DC motor with a highly simplified hardware configuration: use of six-step commutation without current control unit. In addition, the closed-loop stability has been analyzed by using the singular perturbation method. Throughout experimental studies, it is observed that reduced order time delay control effectively compensates for parameter variations and nonlinearities, with a conventional PID control cannot handle with adequate performances. This result shows that reduced order time-delay control enables an economical design without compromising performance. More importantly, the example establishes a case that: a good control method can compensate for the hardware deficiency in a given plant, and as a result it even enables a simpler design of plants at the design stage
Physiological adaptation of two unicellular green algae to pH stress.
Full text linkTwo marine algae, Dunaliella parva and Chlorococcum submarinum were selected to study the effect of pH stress on single celled algae. D. parva has been well characterised physiologically, but not with regards to pH stress. C submarinum has not been so extensively studied, but is known to grow over a wide pH range from pH 4.5 to 10.5. It was of prime importance that the algal cells were grown at the desired extreme values of external pH. Problems were encountered at high levels of pH but were overcome by growing the algae in a fermenter set up as a batch culture. This method of growth was used for both algae at extreme values of external pH and it allowed the accurate control of the media pH by the automatic addition of acid or alkali. pH 7.5 cells were grown in normal flask batch culture. The cell number, cell volume, and chlorophyll content of both algae were determined over a wide range of pH values, showing that differences in external pH had significant effects on individual cells. Protein concentrations were measured and were shown to increase in pH 9.0 grown cells. Determination of cell volume, internal pH and membrane potential have been carried out using radiolabelled isotopes for algae grown over a wide pH range. Cell volume was shown to increase at both acid and alkaline pH values. The internal pH of both algae was found to be at a more neutral pH than the external pH. For both D. parva and C submarinum, the membrane potential increased with increasing external pH. Enzyme activities in crude extracts were measured to establish the effects of external pH changes on metabolic pathways. The activity of these enzymes, taken from different organelles in the cell, was used to investigate the uniformity of internal pH
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