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介绍了GPSRTK高程拟合的理论方法和数学模型,常规的方法是以最小二乘估计值为初值,但不宜发现和处理粗差。为了提高高程拟合精度,采用抗差估计理论在GPSRTK高程拟合的精度分析方法,通过选择综合抗差估计阶段的权函数,不断地迭代,直至权无限趋近于零。 相似文献
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由于测绘工具的飞速发展,测量工作变得也越来越简单,精度也越来越高。但数据处理在测绘工作中仍旧占据重要的位置。其中尤其是不等式约束平差是现代数据处理的趋势。以往的研究中大多以最小二乘模型为研究平台。最小二乘虽然是测绘科学中最为经典的数学模型,然而不难发现最小二乘不具有抗差性能。和极大似然估计则不同,它能抗拒粗差。但是在不等式约束中的应用以往还没这方面的研究。本文通过将和极大似然估计模型引入不等式约束平差问题,并建立相应平差模型。 相似文献
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针对目前测量实践中,拟合圆中观测坐标往往会存在粗差,导致参数精度降低这一具体问题,提出用抗差理论求解拟合圆参数。为此,本文讨论了传统的间接平差和选取迭代法如何实现拟合圆参数求解,并结合生产实践算例证明了选权迭代法能更可靠地得到拟合圆的参数。建议广大测绘工作者根据需要运用抗差理论估计拟合圆参数。 相似文献
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在已知的线性模型中,考虑加权最小二乘估计与线性无偏最小方差估计的结果的差异。发现在两种条件下,加权最小二乘估计与线性无偏最小方差估计的结果趋于一致。 相似文献
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赵超 《中国科学院研究生院学报》2010,27(4):556-562
用于估计马斯京根模型参数的方法很多,但这些方法在数据存在异常值时缺乏抵御异常值影响的抗差性能. 推导出一种有限制条件的参数抗差估计算法,通过含有随机误差和异常误差的人工数据和真实数据比较抗差算法与传统最小二乘算法的抗差性. 研究表明抗差估计算法能减小异常值对参数估值的影响. 相似文献
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《测量平差》是测绘类专业重要的基础核心课程。根据高职高专院校人才培养模式的基本特征，以及测量平差的课程理论性强、公式多、难度大等特点，主要从误差理论和基本平差方法等方面的教学内容和手段角度，针对高职高专《测量平差》的课程教学提出一些见解。 相似文献
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《测量平差》是测绘类专业重要的基础核心课程。根据高职高专院校人才培养模式的基本特征,以及测量平差的课程理论性强、公式多、难度大等特点,主要从误差理论和基本平差方法等方面的教学内容和手段角度,针对高职高专《测量平差》的课程教学提出一些见解。 相似文献
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光束法平差(Bundle Adjustment)一直以来都是计算机视觉及摄影测量领域中的重点研究内容,在光束法平差过程中,损失函数的选择又对平差结果有着重要影响。选择一个合适的损失函数会大大提升平差结果的精度和鲁棒性。为了确定损失函数对平差结果的影响,本文分析比较了Huber、Tukey和Arctan这三种当前广泛应用的损失函数。并通过对比实验,在多组公开数据集上进行测试,从而比较了这几种损失函数的实际性能和精度。本文研究为光束法平差中损失函数选择提供了很好的借鉴和建议。 相似文献
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M. De la Sen 《Journal of The Franklin Institute》2004,341(3):231-254
This paper deals with the pole-placement-type robust adaptive control of continuous linear systems in the presence of bounded noise and a common class of unmodeled dynamics provided that two estimation schemes are used in parallel. Both estimation schemes are introduced in order to minimize the plant identification error by selecting, as plant parameter estimates, a convex combination of both parameter estimates which leads to the selection of one of the estimation schemes, via a switching rule, on time intervals of at least a minimum prefixed residence duration. The weights of the individual parameter vector estimates are provided at each time by an optimization or suboptimization scheme for a quadratic loss function of the possibly filtered tracking error and/or control input. The robust stability of the overall adaptive scheme is ensured by an adaptation relative dead zone which takes into account the contribution of the unmodeled dynamics and bounded noise. The basic results are derived for two different estimation strategies which have either a shared regressor with the plant or individual regressors for the input contribution and its contributed derivatives. In this second case, the plant input is obtained from a similar convex combination rule as the one used for the estimators in the first approach. An extension of the basic strategies is also pointed out including a combined use of the (sub) optimization scheme with a supervisor of past measures for the on-line calculation of the estimator weights in the convex combination. Finally, the extension of the scheme for the use of any number of parametrical estimators is focused on. 相似文献
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This paper demonstrates that hysteresis operators are the optimal estimators for a large class of estimation and decision problems. This class of problems arises whenever a cost is associated with actions needed to process changes in the estimates or decisions. A simple example related to least-squares estimation is used to illustrate and motivate the developments in this paper. Subsequently, the problem of mean-square estimation with minimal cost of actions is investigated. These results provide a justification for the use of hysteresis in many practical signal processing and communication applications. 相似文献
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In this paper, the event-triggered distributed H∞ state estimation problem is investigated for a class of state-saturated systems with randomly occurring mixed delays over sensor networks. The mixed delays, which comprise both discrete and distributed delays, are allowed to occur in a random manner governed by two mutually independent Bernoulli distributed random variables. In order to alleviate the communication burden, an event-triggered mechanism is utilized for each sensor node to decide whether or not its current information should be broadcasted to its neighbors. The aim of this paper is to design event-triggered state estimators such that the error dynamics of state estimation is exponentially mean-square stable with a prescribed H∞ performance index. By resorting to intensive stochastic analysis, sufficient conditions are first derived to guarantee the existence of the desired estimators, and the parameters of the desired distributed estimators are then obtained in light of the feasibility of a certain set of matrix inequalities. A numerical example is employed to illustrate the usefulness of the proposed distributed estimation algorithm. 相似文献
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在深入分析小波脊原理的基础上,针对数字信号瞬时频率提取精度要求,利用小波脊提取数字信号的瞬时频率,并对方法的初始值设置、解析小波参数设置和估计精度设置等关键问题进行了分析并改进.实际信号实验表明,改进算法鲁棒性明显增强,实用价值较大. 相似文献
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Weibull分布基于定数逐次截尾寿命数据的统计分析 总被引：3，自引：0，他引：3
讨论Weibull分布基于定数逐次截尾寿命数据的参数估计，得到了参数的逆矩估计量和区间估计，模拟结果显示在中小样本情况下所给估计量优于参数的最大似然估计． 相似文献
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Jose I. Canelon 《Journal of The Franklin Institute》2018,355(8):3583-3618
Many dynamical systems are continuous-time non-square with unknown mismatched input and output disturbances. For such systems, a universal on-line robust optimal tracking control is often desirable. In this paper, the conventional proportional-integral-differential (PID) controller is utilized as a fictitious PID filter to shape the tracking error in the frequency-domain using a quadratic performance index as a weighting function, such that the robust PID-shaped PI tracker integrated with the equivalent input disturbance (EID) estimator is established to carry out the on-line robust optimal tracking control of the general disturbed system. The benefits and discrepancies of the proposed compensation improvement mechanism over the conventional optimal trackers for continuous-time non-square systems with/without unknown mismatched input and output disturbances are listed as follows: (i) It develops a new net EID estimator without any previously established constraints on the dimensions of the system and on the disturbances; (ii) It provides an efficient estimated-state-feedback-based EID estimator in contrast to the conventional output-feedback-based EID estimators; (iii) It is able to carry out on-line EID estimation of the tracking errors for systems with endogenous/exogenous output disturbances; (iv) It is a universal tracker which can be simply implemented as a plug-in EID estimator for most servo systems, to improve the performance of any existing observers/trackers which are not allowed to be removed from the system. The advantages of the proposed method over two existing outstanding approaches reported in the literature are pointed out using illustrative examples. 相似文献
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Koksal Erenturk 《Journal of The Franklin Institute》2010,347(7):1171-1185
This study presents application of a fuzzy controller to a nonlinear two-mass system control. The proposed controller structure is strengthened with a gray estimator. Firstly, a complete state-space mathematical model for a nonlinear two-mass system is developed and numerically simulated. Then, a fuzzy controller is designed to regulate the speed of the system. In order to perform a dynamic and powerful control action, future error values are estimated by gray modeling technique. The gray estimators of the torsional torque and the load machine speed are tested with open-loop and closed-loop control structures to test the robustness of the proposed method for step changes in input parameters. It is observed that the tracking ability of the gray estimators is not influenced for different operation modes. The performances of the control structures, which are supported with gray estimators, are given and no additional feedbacks are required for robust control action. The simulation results are confirmed by experimental results and conclusions are given. 相似文献
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Shi Liang Zhenyu Liu Chan Qiu Jianrong Tan 《Journal of The Franklin Institute》2018,355(14):6657-6674
This paper focuses on state estimation issues for networked control systems (NCSs) with both control input and observation packet dropouts over user datagram protocol (UDP) communication channels. For such systems, which are usually known as UDP-like systems, the computation cost of the optimal estimator is too high to afford in practice due to exponential growth of complexity. Although quite a few suboptimal estimators could be alternatives for improving the computational efficiency, yet researches on the stability of suboptimal estimators are rarely reported. Based on the generalized pseudo-Bayesian (GPB) algorithm, an efficient suboptimal algorithm is developed for UDP-like systems. More crucially, a sufficient condition is obtained, which guarantees the stability of its mean estimation error covariance. This stability condition explicitly expresses that the rate of observation packet dropout is a critical factor in determining the stability of the proposed GPB estimator, while the rate of control input packet dropout has no influence on it. The results are illustrated by numerical examples. 相似文献
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Modeling uncertainties including parameter uncertainty and unmodeled dynamics hinder the development of high-performance tracking controller for hydraulic servo system. The observation for the unknown state is another issue worthy of attention. In this paper, a new seamless observer-controller scheme for hydraulic servo system is proposed with partial feedback. The position signal and the pressure signal are firstly used to build an extended structure estimation system for the unknown state. The advantage of this estimation system is that the state observer provides an extended structure for the parameter adaptation compared to other state observers. Thus the parameter uncertainty can be handled. An adaptive robust controller is synthesized in this paper which includes the adaptive part and the robust part. The adaptive part is used to eliminate the parameter uncertainty. Then the residuals coming from the parameter adaption and the errors coming from the state observation are taken into consideration in the robust part. Moreover, the unmodeled dynamics is also handled by the robust part. Theoretical analysis proves that a prescribed transient performance and the final tracking accuracy can be guaranteed by the proposed observer-controller scheme in the presence of both parameter uncertainty and unmodeled dynamics. Furthermore, the convergence of the closed-loop controller-observer system is achieved with the parametric uncertainty existed only. Extensive comparative experiments performed on a hydraulic actuator demonstrate the effectiveness of the proposed observer-controller scheme. 相似文献
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对于一个参数进行估计来讲,不仅要考虑估计的精度,还要考虑所得到的估计对于模型拟合的优良程度。通常的损失函数无能为力,而平衡损失函数可以考虑到这两点,本文将在平衡误差损失函数下研究广义Pareto分布参数的Bayes估计问题。在平衡损失函数下导出了参数的Bayes估计并讨论了一类线性形式估计的可容许性和不可容许性。 相似文献