Effects of Extra Sinusoidal Inputs to Nonlinear Systems
01 Dec 1962-Journal of Basic Engineering (American Society of Mechanical Engineers Digital Collection)-Vol. 84, Iss: 4, pp 559-569
About: This article is published in Journal of Basic Engineering.The article was published on 1962-12-01. It has received 48 citations till now. The article focuses on the topics: Nonlinear system.
Citations
More filters
01 Dec 2016
TL;DR: In this article, quantization noise and harmonic distortion are reduced by combinations of small noise dithers and large high-frequency periodic dither, and the results show reasonable correspondence to simulation and a significant reduction in noise due to quantization and element mismatch.
Abstract: The resolution of precision mechatronic systems is fundamentally limited by the the noise and distortion performance of digital-to-analog converters. The sources of noise and distortion include quantization error, non-linearity, thermal noise, and semiconductor noise. In precision control applications, the primary limitation is harmonic distortion due to quantization and element mismatch. In this article, quantization noise and harmonic distortion are reduced by combinations of small noise dithers and large high-frequency periodic dithers. Theoretical predictions are confirmed experimentally on a closed-loop nanopositioning system. The results show reasonable correspondence to simulation and a significant reduction in noise due to quantization and element mismatch.
5 citations
Cites background from "Effects of Extra Sinusoidal Inputs ..."
...non-linearity is due to the smoothing effect on the nonlinearity [11]–[14]....
[...]
01 Jan 2016
TL;DR: This paper draws key insights into the mechanism by which the high-frequency stimulation signal in the brain in DBS can help reduce the `equivalent gain' of the low-frequency tremor component and thus help attenuate the tremors.
Abstract: Parkinson's disease is a neurodegenerative disorder of the central nervous system and among the symptoms, rest tremors is one of the key symptoms. Deep Brain Stimulation (DBS) is a treatment that effectively manages the tremor symptoms in Parkinson's disease. Despite being a successful treatment option, its underlying principle and the mechanism by which it attenuates tremors is not yet fully understood. Since existing methods for tuning DBS parameters are largely trial and error approaches, understanding how DBS works can help reduce time and costs. Further, understanding how DBS works may also help in understanding the mechanism by which the tremors are caused in the first place, which still remains a contested issue. Understanding these mechanisms ultimately could lead to accurate diagnosis tools and better treatment strategies for Parkinson's disease. In this paper, we set out to analyse how a high-frequency stimulation signal in the brain in DBS can help control the low-frequency rest tremors observed in Parkinson's patients. With a simplistic feedback loop framework that captures the key elements in the sensorimotor loop (the feedback loop consisting of sensory functions and motor functions) in humans, we draw key insights into the mechanism by which the high-frequency stimulation signal can help reduce the ‘equivalent gain’ of the low-frequency tremor component and thus help attenuate the tremors. We verify these observations with numerical examples and a bench top experimental example, and close with a few concluding remarks.
4 citations
Cites background from "Effects of Extra Sinusoidal Inputs ..."
...Finally, the equivalent gain of the saturation is given by [13],...
[...]
...Consider the input to the nonlinear element (saturation in our case) is of the form [13],...
[...]
...First let us consider an input to the nonlinear element as a sinusoidal signal with a constant bias [13]....
[...]
23 May 1990
TL;DR: In this article, a rule-based system is developed which compensates for dead-zone phenomena in a position control servo-mechanism, based around a supervisory module which is designed to detect and avoid undesirable nonlinear control phenomena such as steady state errors, limit cycling or excursions into unwanted zones.
Abstract: The paper presents an Al alternative to classical control compensation procedures for input nonlinearities. Specifically, a rule-based system is developed which compensates for dead-zone phenomena in a position control servo-mechanism. The rule-based system compensator is based around a supervisory module which is designed to detect and avoid undesirable nonlinear control phenomena such as steady state errors, limit cycling or excursions into unwanted zones. The heuristics within the supervisor also allow abnormal situations to be detected and avoided. The technique is thus potentially far more powerful than conventional non-linear compensation procedures such as `dither'. As such, it constitutes an intelligent compensator for system input nonlinearities which may be generalizated to other nonlinearity types.
3 citations
TL;DR: In this article, a method in which an extra signal of higher frequency is added to the input of the receptor, the nonlinearities can be altered and the accuracy improved, and the results have been compared with those predicted by the theory.
Abstract: Photodiodes and photo transistors are presently being applied to many fields to convert optical signals into electrical signals. One application of these devices is in a position detection system. The accuracy of such a system is limited by nonlinearities due to these devices. Through signal perturbation, a method in which an extra signal of higher frequency is added to the input of the receptor, the nonlinearities can be altered and the accuracy improved. The theory for this technique is well understood; however, very little experimental data have been reported. This method has been experimentally tested and the results have been compared with those predicted by the theory.
3 citations
TL;DR: In this paper, an analog computer has been used to simulate a high-gain adaptive control method for regulating the speed of an internal combustion engine, where an on-off relay main tains the high gain in the forward loop that is necessary to produce a one-to-one relationship between input and output.
Abstract: An analog computer has been used to simulate a high-gain adaptive control method for regulating the speed of an internal combustion engine. A nonlinear element (an on-off relay) main tains the high gain in the forward loop that is necessary to produce a one-to-one relationship between input and output. Such high gain leads to limit-cycle behaviour in the model. A high-frequency dither at the relay input acts as a stabilizing signal to deal with this problem.
2 citations