Nonlinear Sampled-Data Systems with a Generalized Hold Polynomial-Function for Fast Sampling Rates

Zeng, Cheng; Xiang, Shuwen; He, Yi; Ding, Qian

doi:10.1007/s11424-019-7404-0

Cited by 5 publications

(4 citation statements)

References 27 publications

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“…The values of dx and dy can thus be calculated, and the location of the subpixel matching point that minimizes the value can be determined [14][15]…”

Section: Image Recognition Of Photovoltaic Cell Occlusion Based On Su...mentioning

confidence: 99%

Image Recognition of Photovoltaic Cell Occlusion Based on Subpixel Matching

Jin,

Yu,

Yin

et al. 2024

EAI Endorsed Trans Energy Web

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INTRODUCTION: During the operation of large photovoltaic power stations, they are often shielded by dust and bird droppings, which greatly reduce the power generation and even cause fires. Analysis of PV cell occlusion image recognition accuracy based on sub-pixel matching. OBJECTIVES: In order to find the location of the pv cells, we use the method of subpixel image matching. Improve recognition accuracy. METHODS: When the power plant is running normally, taken the original image for photovoltaic power station as the original sample, and then using the subpixel gradient matching algorithm, to match the original image and find out that the minimum matching values. RESULTS: If the calculation results is greater than a specified threshold, When the calculated result is greater than the specified threshold, the power station is considered abnormal. CONCLUSION: The experimental process shows that this method can better judge the operating status of photovoltaic power station, and can find out the location of mismatched photovoltaic cells more accurately, and the calculation accuracy reaches sub-pixel level.

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“…The values of dx and dy can thus be calculated, and the location of the subpixel matching point that minimizes the value can be determined [14][15]…”

Section: Image Recognition Of Photovoltaic Cell Occlusion Based On Su...mentioning

confidence: 99%

Image Recognition of Photovoltaic Cell Occlusion Based on Subpixel Matching

Jin,

Yu,

Yin

et al. 2024

EAI Endorsed Trans Energy Web

View full text Add to dashboard Cite

show abstract

“…Using ( 16), ( 14) can be written as in (17) with l = 1, that is, the first-time shifted sample does not occur until t = (1 + m)T). Since the LRO ACS is underdamped, (17) may be further rewritten as in (18).…”

Section: Intersample Ripple In the Z-domainmentioning

confidence: 99%

“…However, simply increasing the order of hold may not alleviate the undesirable intersample behavior that arises due to additional dynamics introduced under multirate operation. 17 On the other hand, if a reconstruction filter is employed that has the same polynomial basis as used by the coordinated multi-axis attitude maneuver planner, then maneuver trajectories can in principle be reproduced without loss of information, at any sampling rate. For this reason, we propose a high-order Chebyshev-type interpolating filter in this article.…”

Section: Introductionmentioning

confidence: 99%

Waypoint following dynamics of a quaternion error feedback attitude control system

Karpenko

Halverson

Besser

2021

Proceedings of the Institution of Mechanical Engineers, Part G:

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Closed-loop attitude steering is a concept for implementing an attitude trajectory by using a conventional quaternion error feedback controller to track the time-varying attitude reference, rather than to simply regulate to a desired orientation. This is done by sampling the reference input and executing the maneuver as a sequence of closely spaced regulating commands that are read out from the spacecraft’s command buffer. The idea has been employed in practice to perform zero-propellant maneuvers on the International Space Station and minimum-time maneuvers on NASA’s TRACE space telescope as well as NASA’s Lunar Reconnaissance Orbiter (LRO). A challenge for operational implementation of the idea is the limited capacity of a space vehicle’s command storage buffer, which is normally not designed with attitude tracking in mind. One approach to mitigate the problem is to downsample-and-hold the attitude commands so that the attitude control system (ACS) regulates to a series of waypoints. This article explores the waypoint following dynamics of a quaternion error feedback control law for such an approach. It is shown that downsample-and-hold induces a ripple between downsamples that causes the satellite angular rate to significantly overshoot the desired limit. Analysis in the z-domain is carried out in order to understand the phenomenon. An interpolating Chebyshev-type filter is proposed that allows the desired attitude trajectory to alternatively be encoded in terms of a small set of filter coefficients. Using the interpolating filter, the continuous-time reference trajectory can be reconstructed and issued at the ACS rate but with significantly reduced memory requirements. The ACS of the LRO is used as an example to illustrate the behavior of a practical ACS.

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“…Therefore, an open issue is the design of hardware systems capable of S&H advanced systems. Studies on the use of S&H-β in control systems report relevant results for improving the overall performance [41][42][43][44][45][46]. In this perspective, the construction of low cost general S&H may be a valuable option for obtaining equipment more friendly to the environment while not posing significant financial requirements.…”

Section: The Transfer Functions Of the Sandhmentioning

confidence: 99%

A Review of Sample and Hold Systems and Design of a New Fractional Algorithm

Ortigueira

Machado

2020

Applied Sciences

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Digital systems require sample and hold (S&H) systems to perform the conversion from analog to digital and vice versa. Besides the standard zero and first order holds, we find in the literature other versions, namely the fractional and exponential order holds, involving parameters that can be tuned to produce a superior performance. This paper reviews the fundamental concepts associated with the S&H and proposes a new fractional version. The systems are modeled both in the time and Laplace domains. The new S&H stemming from fractional calculus generalizes these devices. The different S&H systems are compared in the frequency domain and their relationships visualized by means of hierarchical clustering and multidimensional scaling representations. The novel strategy allows a better understanding of the possibilities and limitations of S&H systems.

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Nonlinear Sampled-Data Systems with a Generalized Hold Polynomial-Function for Fast Sampling Rates

Cited by 5 publications

References 27 publications

Image Recognition of Photovoltaic Cell Occlusion Based on Subpixel Matching

Image Recognition of Photovoltaic Cell Occlusion Based on Subpixel Matching

Waypoint following dynamics of a quaternion error feedback attitude control system

A Review of Sample and Hold Systems and Design of a New Fractional Algorithm

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