共查询到20条相似文献，搜索用时 31 毫秒
1.
This paper deals with the state estimation of nonlinear discrete systems described by a multiple model with unknown inputs. The main goal concerns the simultaneous estimation of the system's state and the unknown inputs. This goal is achieved through the design of a multiple observer based on the elimination of the unknown inputs. It is shown that the observer gains are solutions of a set of linear matrix inequalities. After that, an unknown input estimation method is proposed. An academic example and an application dealing with message decoding illustrate the effectiveness of the proposed multiple observer. 相似文献
2.
The problem of constructing functional observers for linear systems with unknown inputs is considered. Necessary and sufficient conditions for the existence of a proper observer (without differentiations) are revisited. A simple and explicit form of a functional observer is presented. It is shown that when such observer is not proper, it is still possible to use the High-Order Sliding Mode differentiator to implement it. Nevertheless, in such case, additional conditions on the system and the unknown input are required. 相似文献
3.
Jeremy Van Gorp Michael Defoort Kalyana C. Veluvolu Mohamed Djemai 《Journal of The Franklin Institute》2014
This paper addresses the state observation and unknown input estimation of a class of switched linear systems with unknown inputs. This class of systems may have modes in which the state is not fully observable. A state transformation allows implementing two suitable reduced-order observers. The first one, based on second order sliding mode techniques, is proposed to reconstruct the discrete state in the presence of unknown inputs. The second one, based on gathering partial information from individual modes of the switched system and on higher order sliding mode techniques, is introduced to estimate the continuous state. Then, the observer injection signal of the first second order sliding mode observer is used to estimate the unknown inputs. Simulation results highlight the efficiency of the proposed method. 相似文献
4.
《Journal of The Franklin Institute》2023,360(14):10564-10581
In this work, we investigate consensus issues of discrete-time (DT) multi-agent systems (MASs) with completely unknown dynamic by using reinforcement learning (RL) technique. Different from policy iteration (PI) based algorithms that require admissible initial control policies, this work proposes a value iteration (VI) based model-free algorithm for consensus of DTMASs with optimal performance and no requirement of admissible initial control policy. Firstly, in order to utilize RL method, the consensus problem is modeled as an optimal control problem of tracking error system for each agent. Then, we introduce a VI algorithm for consensus of DTMASs and give a novel convergence analysis for this algorithm, which does not require admissible initial control input. To implement the proposed VI algorithm to achieve consensus of DTMASs without information of dynamics, we construct actor-critic networks to online estimate the value functions and optimal control inputs in real time. At last, we give some simulation results to show the validity of the proposed algorithm. 相似文献
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《Journal of The Franklin Institute》2019,356(15):8255-8277
This paper focuses on the optimal tracking control problem (OTCP) for the unknown multi-input system by using a reinforcement learning (RL) scheme and nonzero-sum (NZS) game theory. First, a generic method for the OTCP of multi-input systems is formulated with steady-state controls and optimal feedback controls based on the NZS game theory. Then a three-layer neural network (NN) identifier is introduced to approximate the unknown system, and the input dynamics are obtained by using the derivative of the identifier. To transform the OTCP into a regulation optimal problem, an augmentation of the multi-input system is constructed by using the tracking error and the commanded trajectory. Moreover, we use an NN-based RL method to online learn the optimal value functions of all the inputs, which are then directly used to calculate the optimal tracking controls. All the NN weights are tuned synchronously online with a newly introduced adaptation based on the estimation error. The convergence of the NN weights and the stability of the closed-loop system are analyzed. Finally, a two-motor driven servo system and another nonlinear system are presented to illustrate the feasibility of the algorithm for both linear and nonlinear multi-input systems. 相似文献
6.
The problem of robust exact control for a Stewart platform with smooth bounded unknown inputs is considered. This platform has three degrees of freedom and it is used as a remote surveillance device. We consider high-order sliding mode observers to provide both theoretical exact observation and unknown input identification. In this paper, a methodology is proposed to select the most adequate control strategy for unknown external perturbation identification. The results obtained are illustrated by simulations. 相似文献
7.
In this paper, the robust fault detection filter (RFDF) design problems are studied for nonlinear time-delay systems with unknown inputs. Firstly, a reference residual model is introduced to formulate the robust fault detection filter design problem as an H∞ model-matching problem. Then appropriate input/output selection matrices are introduced to extend a performance index to the time-delay systems in time domain. The reference residual model designed according to the performance index is an optimal residual generator, which takes into account the robustness against disturbances and sensitivity to faults simultaneously. Applying robust H∞ optimization control technique, the existence conditions of the robust fault detection filter for nonlinear time-delay systems with unknown inputs are presented in terms of linear matrix inequality (LMI) formulation, independently of time delay. An illustrative design example is used to demonstrate the validity and applicability of the proposed approach. 相似文献
8.
The paper studies the problem of simultaneously estimating the state and the fault of linear stochastic discrete-time varying systems with unknown inputs. The fault and the unknown inputs affect both the state and the output. However, if the dynamical evolution models of the fault and the unknown inputs are available the filtering problem will be solved by the Optimal three-stage Kalman Filter (OThSKF). The OThSKF is obtained after decoupling the covariance matrices of the Augmented state Kalman Filter (ASKF) using a three-stage U–V transformation. Nevertheless, if the fault and the unknown inputs models are not perfectly known the Robust three-stage Kalman Filter (RThSKF) will be applied to give an unbiased minimum-variance estimation. Finally, a numerical example is given in order to illustrate the proposed filters. 相似文献
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This paper proposes an alternative fault detection (FD) scheme, in which the so-called residual signals are generated by means of a projection of process input data. This is the major difference to the existing model-based and data-driven FD schemes, where residual generator is realized based on the process input and output relationship/dynamics. Moreover, this way of residual generation avoids the parameter identification procedure and also allows us to address deterministic disturbances (unknown inputs), which be paid often less attention by data-driven FD methods. In this fashion, the FD issue reduces to detect change of a random matrix. Since it is difficult to directly measure this change, so the trace of a matrix is adopted as the evaluation function. Furthermore, the threshold can be set by considering the boundedness of disturbance. The effectiveness of the proposed method is verified by a simulation study on an inverted pendulum system. 相似文献
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In this paper, a Russell non-radial measure of eco-efficiency is proposed. Data Envelopment Analysis (DEA) is used for the computations. The inputs considered are the damage indicators provided by the Ecoindicator 99 methodology for Life Cycle Impact Assessment (LCIA). The single output is consumer price, used as a surrogate of economic value. After projecting onto the efficient frontier using input orientation and obtaining efficient target values for the damage indicators, additional DEA models are solved in order to compute corresponding scale elasticities bounds. The proposed approach is illustrated on a small sample of household electric and electronic products. The results confirm that mobile phones, desktop computers and vacuum cleaners are eco-efficient and, of these, only mobile phones are scale efficient. Bounds on the scale elasticity of all products are reported. Most products show decreasing eco-efficiency returns to scale. 相似文献
11.
This paper develops a robust adaptive neural network (NN) tracking control scheme for a class of strict-feedback nonlinear systems with unknown nonlinearities and unknown external disturbances under input saturation. The radial basis function NNs with minimal learning parameter (MLP) are employed to online approximate the uncertain system dynamics. The adaptive laws are designed to online update the upper bound of the norm of ideal NN weight vectors, and the sum of the bounds of NN approximation errors and external disturbances, respectively. An auxiliary dynamic system is constructed to generate the augmented error signals which are used to modify the adaptive laws for preventing the destructive action due to the input saturation. Moreover, the command filtering backstepping control method is utilized to overcome the shortcoming of dynamic surface control method, the tracking-differentiator-based control method, etc. Our proposed scheme is qualified for simultaneously dealing with the input saturation effect, the heavy computational burden and the “explosion of complexity” problems. Theoretical analysis illuminates that our scheme ensures the boundedness of all signals in the closed-loop systems. Simulation results on two examples verify the effectiveness of our developed control scheme. 相似文献
12.
城市土地利用效率是影响城市化进程的重要因素,提升城市土地利用效率对于推动区域协调发展具有重要意义,但是如何差异化提升不同区域城市土地利用效率有待研究。本文首先基于生产要素理论,分析城市生产要素投入对城市土地利用效率的影响机理,其次利用1996—2017年中国30个省（市、区）的数据实证分析资本、劳动力与创新投入对土地利用效率的作用,并探讨不同工业化阶段的差异化影响。主要结论如下：①总样本的回归结果显示,资本投入、劳动力投入以及创新投入对城市土地利用效率产生显著的正向作用。②不同工业化阶段的异质性回归结果显示,在工业化初期阶段,资本与劳动力投入能够显著促进城市土地利用效率的提升;在工业化中期阶段,资本、劳动力与创新投入都能够对城市土地利用效率产生显著的正向影响;在工业化后期阶段,资本投入对城市土地利用效率的影响显著为负,而劳动力和创新投入对城市土地利用效率影响显著为正。研究表明,在不同工业化阶段,影响城市土地利用效率的因素及其作用强度和方向均有差异。因此,为更加集约利用土地,需制定差别化的政策,促进不同工业化阶段城市土地利用效率的提升。 相似文献
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This article presents a multi-lagged-input based data-driven adaptive iterative learning control (M-DDAILC) method for nonlinear multiple-input-multiple-output (MIMO) systems by virtue of multi-lagged-input iterative dynamic linearization (IDL). The original nonlinear and non-affine MIMO system is equivalently transformed into a linear input-output incremental counterpart without loss of dynamics. The proposed learning law utilizes the desired trajectory to cancel the influence from iteration-by-iteration variations, as well as additional multi-lagged inputs to improve control performance. The developed iterative estimation law is more effective and also makes estimation of the unknown parameters easier because the dynamics for each parameter to represent are decreased by dividing the system into multiple components in the multi-lagged-input IDL formulation. Moreover, the proposed M-DDAILC does not need an explicit and accurate model. It is proved to be iteratively convergent with rigorous analysis. Both a numerical example and a practical application to a permanent magnet linear motor are provided to verify the validity and applicability of the proposed method. 相似文献
14.
开放创新条件下的资源投入测度及政策含义 总被引：1，自引：0，他引：1
基于Lundvall教授提出的技术创新的两种模式和学习型经济理论,探讨开放式创新环境下提高我国自主创新能力的关键因素。认为在经济全球化环境下,开放式创新是当前技术创新的重要特点,开放式创新与自主创新是相辅相成的关系,开放环境下的自主创新强调创新多种元素的集成和整合。提出以全面创新投入替代研发投入来反映技术投入将更为合理和完整,并对国内时间序列数据进行Granger因果检验,对国际面板数据进行计量经济检验加以实证验证。最后根据分析结果提出现阶段增强我国自主创新能力的政策建议。 相似文献
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本文对农桐复合系统的营养元素输入、输出和平衡进行了分析,结果表明：现行农桐复合系统每公倾面积N、P、K的吸收量分别为276.2kg,92.1kg和172.2kg,输入量分别为370.2kg、181.5kg和113.5kg,输入与输出比为：氮1.34,磷1.97,钾0.66,系统的氮和磷处于平衡状态或稍有盈余,而钾处于亏损状态;系统的有机态营养元素输入量偏小,有机态氮输入量为无机态氮输入量的68%,而有机态磷输入量仅为无机态磷输入量的21%;系统中的氮、磷、钾三要素的投入比例不协调,营养元素输入量中,N：P：K＝1：0.49：0.31,而农林植物营养元素吸收量中氮、磷、钾三要素的比例为1：0.33：0.62,投入的磷养分相对偏多,钾偏少。 相似文献
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近年来,传统企业纷纷抓住数字技术机遇,致力于进行数字导向的战略更新活动。然而,现有文献对于传统企业数字导向战略更新前因变量的探讨还比较有限。本研究基于IS战略化和战略实践观,提出了“战略化活动-忘却学习-数字导向战略更新”的研究框架,构建了自上而下的创业导向活动、自下而上的组织即兴活动,通过组织忘却学习影响数字导向战略更新的理论模型。本文采用两种研究方法,即问卷调查和案例研究方法,探讨数字导向战略更新的前因及实现路径。研究表明：创业导向和组织即兴均有利于传统企业的数字导向战略更新;忘却学习分别在创业导向与数字化探索创新、组织即兴与数字化探索创新的关系中起到中介作用。本研究细致刻画了传统企业如何通过忘却学习进行数字导向战略更新的作用机制,具有重要的理论及实践价值。 相似文献
17.
摘要：数字经济下的企业面临着复杂多变的外部环境,开展数字导向战略更新活动成为传统企业生存和发展的关键。为此,本研究选取林清轩的单案例研究,探索数字导向战略更新的实现机理和演进路径。研究发现：（1）企业在开展数字化活动时,存在着认知、行动及商业模式等惯性力量,而组织学习是一种克服组织惯性的有效方式;（2）实现数字导向战略更新是一个过程,经过了数字化探索、数字化提升和数字化赋能阶段,在各阶段中,企业依次克服了认知惯性、行动惯性和商业模式惯性;（3）数字导向战略更新活动呈现出从IT端、营销端到流程端的数字基础设施改进、数字营销活动推广和数字业务流程构建的演进路径。 相似文献
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应激会对动物的学习记忆能力产生影响,这种影响呈一种倒U型关系,即当应激强度过大或时间过长时这种影响往往是一种损伤,而适度的应激会对学习记忆产生促进作用。目前认为应激激活了下丘脑-垂体-肾上腺（hypothalamo-pituitary-adrenal,HPA）轴,诱导糖皮质激素的释放。适量的糖皮质激素会促进长时程增强（long-term potentiation,LTP）的形成,从而促进学习记忆。血清/糖皮质激素诱导激酶（serum and glucocorticoid regulated protein kinase,SGK）作为糖皮质激素诱导的一个激酶,参与了多种离子通道的调节,能够促进神经元的存活和轴突的再生。研究发现SGK的表达也会促进空间学习记忆能力。 相似文献
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《Journal of The Franklin Institute》2023,360(14):10582-10604
In this paper, the optimal model reference adaptive control (MRAC) problem is studied for the unknown discrete-time nonlinear systems with input constraint under the premise of considering robustness to uncertainty. Through an input constraint auxiliary system, a new adaptive-critic-based MRAC algorithm is proposed to transform the above problem into the optimal regulation problem of the auxiliary error system with lumped uncertainty. In order to realize the chattering-free sliding model control for the auxiliary error system, an action-critic variable is introduced into the adaptive identification learning. In this case, the closed-loop control system is robust to the disturbance and the neural network approximation error. The uniformly ultimate bounded property is proved by the Lyapunov method, and the effectiveness of the algorithm is verified by a simulation example. 相似文献