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1.
Xiaonan Dong Chengzhi Yuan Paolo Stegagno Wei Zeng Cong Wang 《Journal of The Franklin Institute》2019,356(10):5049-5072
This paper studies the problem of composite synchronization and learning of multiple coordinated robot manipulators subject to heterogeneous nonlinear uncertain dynamics under the leader-follower framework. A new two-layer distributed adaptive learning control scheme is proposed, which consists of the first-layer distributed cooperative estimator and the second-layer decentralized deterministic learning controller. The first layer aims to enable each robotic agent to estimate the leader’s information. The second layer is responsible for not only controlling each individual robotic agent to track over desired reference trajectory, but also accurately identifying/learning each robot’s nonlinear uncertain dynamics. Design and implementation of this two-layer distributed controller can be carried out in a fully-distributed manner, which do not require any global information including global connectivity of the communication network. The Lyapunov method is applied to rigorously analyze stability and parameter convergence of the resulting closed-loop system. Numerical simulations on a team of two-degree-of-freedom robot manipulators have been conducted to demonstrate the effectiveness of the proposed results. 相似文献
2.
A design procedure is presented leading to a least time suboptimal feedback control law for nonlinear systems in the presence of “small disturbances”. The proposed method is based on the theory developed for a small-deviation suboptimal control law for the case of linear systems. To clarify the method, a problem of guiding an aircraft to a terminal take-off area in the least time is given as a simulation example. 相似文献
3.
This paper proposes a control algorithm for networks of multiple heterogeneous robot manipulators, which solves the leader–follower and the leaderless consensus problems in the operational space. In the leader–follower scenario, the controller ensures that all the robots in the network asymptotically reach a given leader pose (position and orientation), provided that, at least, one follower robot has access to the leader pose. Without a leader pose, in the leaderless problem, the robots asymptotically reach a pose of consensus. The controller is a simple distributed proportional plus damping injection (P+d) scheme which does not require velocity measurements. A singularity-free representation, unit quaternions, is used to describe the orientation of each manipulator. The paper presents some simulations, with a network of six 6-Degrees-of-Freedom (DoF) manipulators, and experiments, with a network of three 6-DoF manipulators, to show the effectiveness of the proposed controller. 相似文献
4.
Manipulating flexible objects stirs a great deal of interest due to the potential applications in industry. Most previous research work with multiple manipulators, however, focused on developing control strategies for the manipulation of rigid bodies. This paper seeks to develop simple yet practical and efficient control scheme that enables cooperating arms to handle a flexible beam. Specifically the problem studied herein is that of two arms rigidly grasping a flexible beam and capable of generating forces/moments in such a way as to move a flexible beam along a predefined trajectory. The paper develops a sliding mode control law that provides robustness against model imperfection and uncertainty. It also provides an implicit stability proof. Given the bounds of uncertainty in the model of the flexible beam and choosing a switching surface that enforces trajectory tracking, a control algorithm is designed to push the states to remain on the switching surface. Simulation results for two three joint arms moving a flexible beam are presented to validate the theoretical results. 相似文献
5.
In this paper, optimized interaction control is investigated for human-multi-robot collaboration control problems, which cannot be described by the traditional impedance controller. To realize global optimized interaction performance, the multi-player non-zero sum game theory is employed to obtain the optimized interaction control of each robot agent. Regarding the game strategies, Nash equilibrium strategy is utilized in this paper. In human-multi-robot collaboration problems, the dynamics parameters of the human arm and the manipulated object are usually unknown. To obviate the dependence on these parameters, the multi-player Q-learning method is employed. Moreover, for the human-multi-robot collaboration problem, the optimized solution is difficult to resolve due to the existence of the desired reference position. A multi-player Nash Q-learning algorithm considering the desired reference position is proposed to deal with the problem. The validity of the proposed method is verified through simulation studies. 相似文献
6.
《Journal of The Franklin Institute》2023,360(8):5794-5810
In the study, an adaptive event-triggered control strategy is proposed for image-based visual servoing of eye-to-hand robot manipulators, where the camera used does not need to be calibrated, and the dynamics behavior of manipulator is considered in design and analysis. To address the uncertainty in camera parameters and the nonlinearity in robot dynamics, and accommodate the errors between the real-time control signals and the piecewise-constant event-triggered control signals, a new and novel robust adaptive estimation approach is developed, and well fused with visual feedback control design so that the boundedness of all closed-loop signals, and the asymptotic convergence of image error towards zero are established simultaneously. Besides rigorous proof in theory, the obtained results are also confirmed by comparative simulation tests. 相似文献
7.
This research contributes to the intra-organization, inter-organization, and new product development (NPD) management literature by studying the impact of a firm's internal organizational design on the communication within and performance of NPD projects conducted with strategic alliance partners. The empirical data were collected from three in-depth case studies of network lead companies (NLCs) operating in different industries. The three NLCs have different internal organizational designs, ranging from very flexible “organic” to very rigid “mechanistic.” In each NLC, a successful new-to-firm product development project was chosen for further detailed investigation. First, we identify the role the alliance's NPD project characteristics and industry characteristics play in determining the “intensity level” and “media richness” of communication required between the alliance's NPD project partners. Then, we examine how the internal organizational design influences the actual intensity and media richness of communication of the alliance's NPD project that matches our assumptions of what is required. 相似文献
8.
This study focuses on a sampled-data fuzzy decentralized tracking control problem for a quadrotor unmanned aerial vehicle (UAV) under the variable sampling rate condition. To this end, the overall dynamics of the quadrotor is expressed as a decentralized Takagi–Sugeno (T–S) fuzzy model interconnected with each other. Although the proposed decentralized control technique divides the overall UAV control system into attitude and position subsystems, the stability of the entire control system is guaranteed. Besides, in this paper, the model uncertainty, interconnection, and reference trajectory are considered as disturbances acting on the tracking error. To attenuate these disturbances, a novel sampled-data tracking control design technique is derived based on a linear reference model to be tracked and the time-dependent Lyapunov–Krasovskii functional (LKF). By doing so, both the stability of the tracking error dynamics and the minimization of tracking performance are guaranteed. Also, the proposed tracking control design method is derived as a linear matrix inequality (LMI)-based optimal problem. Finally, a simulation example is provided to demonstrate the effectiveness and feasibility of the proposed design methodology. 相似文献
9.
In the field of technology policy, few challenges are more intriguing than understanding the nature of technical and market trends. This paper deals with this problem by using the sociotechnical constituencies approach in order to integrate the treatment of “micro”/“macro” issues — from product to industry. The case study is that of the microprocessor industry where at present a Risc (reduced instruction set computer) technology is emerging in a field where a powerful and far-from-exhausted Cisc (complex instruction set computer) technology tends to occupy almost every segment of the market. The analysis reveals how emerging product-constituencies do implement pro-active trend-creating strategies in order to establish themselves as industrial trends, and, by so doing, they simultaneously re-define the existing content of the “macro” industrial level. The study also reveals the important role of the nature and maturity of microprocessor technology in conditioning the constituency-building strategies implemented by different players. Microprocessor technology is specifically characterised as an architectural, codified-knowledge component with indirect network externalities and weak appropriability regime. Finally, the paper also highlights the potential risks of both fragmentation and complete proprietary control of technology in technological processes involving strongly competitive situations. 相似文献
10.
Gerhard H. R. Reisig 《Information processing & management》1978,14(6):405-417
Information-systems are classified into two types, termed “Evidence-of Existence” and “Presentation” of information. The objective of the evidence-type system lies in the domain of documentation and retrieval of information. The structure of this system-type is developed, with application of cybernetic concepts, as an isomorphic model in analogy to the system-structure of communication technology. The latter postulates three criteria of structuring: (1) Source-Channel-Sink, with input-output characteristics, (2) Filter-type communication-channel, (3) Reversable code. These criteria are applied to the structuring of information-systems of the evidence-of-existence type. For the purpose of two-way communication the information-systems have to be represented by closed-loop models. The selective-retrieval requirements necessitate the system-channel to be a filter of information. These information-filters are implemented by keyword-phrases, being identical with the codewords. They yield a uniquely decodable code which is totally reversible to adequately serve both the documentation and the retrieval of documents. It is proven that hierarchic information-systems, applying categorization or subject-heading objects of information, do not meet the mandatory code-requirements. The inherent coding-deficiencies of hierarchic systems generate intolerable retrieval ambiguities. The same critique applies to the thesaurus concept. The development of a novel species of thesaurus is suggested, realizing a kind of Linnéan encyclopedia of general human knowledge, presenting all relevant interrelations of objects of knowledge. Such thesaurus would provide the much needed support for formulating efficient search queries. Other relevant features of communication technology, like the information-potential, should be isomorphically transformed into information-system models. 相似文献
11.
Ruth M. Stock-Homburg Shannon L.M. Heald Christian Holthaus Nils Lennart Gillert Eric von Hippel 《Research Policy》2021,50(8):104068
Problem-solving by everyday individuals is thought to occur as a two-step process. First, an individual identifies or formulates a problem, followed by entering into a subsequent search to find the best solution. Here, however, we consider an alternative process that everyday individuals may use for solution finding first theorized by von Hippel and von Krogh (2016). Specifically, von Hippel and von Krogh proposed that everyday individuals may sometimes discover a solution and the need it satisfies simultaneously without the need for apriori problem formation, a cognitive process they called “need-solution pair recognition”. Utilizing a rich literature from psychology and neuroscience, we propose that seemingly spontaneous discoveries found by need-solution pair recognition are natural products of the object recognition system and its underlying mechanisms. This view asserts that on encountering an object and reasoning how it might be used (i.e. functional object understanding), an individual's perception of an object may culminate in recognizing the object as a solution, and in some cases, as a solution to a problem previously unknown to him or her, thus bypassing formal problem-formulation and active solution searching entirely. To empirically test this view, we manipulated the ability of everyday individuals to functionally reason about objects while we examined the spontaneous occurrence of solutions found by either need-solution pair recognition or traditional problem-first problem-solving. Consistent with our hypothesized mechanism, our results indicate that need-solution pair recognition occurs more frequently when constraints on functional object understanding are reduced. That is, we found that needsolution pair discoveries outpaced solutions found from traditional problem solving, in environments with unfamiliar objects, where participants were not directed to solve specific problems. Our results provide clear evidence that everyday individuals in the household sector do not always innovate through traditional problem-solving processes, but instead may arrive at solutions as they recognize and reason about objects. Implications for research and practice in household innovation, and for innovation more generally are considered. 相似文献
12.
文章使用了UG进行模具的设计,并分别导出符合VRML2.0标准的组成装配体的各个文件;再使用VRMLPad软件使场景之间建立锚接关系、对导入的对象进行控制并调整模型在位置。通过实例说明了虚拟装配过程,并应用到教学中取得了良好的效果。 相似文献
13.
Mohamed Hamdy Raafat Shalaby Mostafa Sallam 《Journal of The Franklin Institute》2018,355(14):6286-6299
This paper presents the design of a hybrid partial feedback linearization and deadbeat control scheme for a nonlinear gantry crane with friction to control its position and sway angle. The partial feedback linearization is used to linearize the nonlinear model and to stabilize its internal dynamics. In many crane applications, it's necessary to accelerate the system response. As a result, this will cause oscillation in the position as well as the sway angle. So, the deadbeat controller is added to get the desirable accelerated response without any oscillation or adverse effects on the internal dynamics stability. By using Lyapunov stability method, the proposed scheme is proved to be globally stable, with converging tracking errors to the desired performance. The simulation results are accomplished to evaluate the effectiveness of the proposed scheme and to demonstrate its reliability to control crane systems with comparative results. 相似文献
14.
In most real-life bilateral teleoperators the available physical parameters are uncertain and the communications exhibit variable time-delays. In order to confront these situations and only assuming that a bound of the time-delays is known, the present work reports an adaptive controller which ensures asymptotic convergence of both position errors and velocities to zero, provided that a sufficient condition on the control gains is met. Compared to previous related works that only treated constant time-delays, the stability analysis does not rely on the cascade interconnection structure of the local and remote nonlinear dynamics and the linear interconnection map. Instead, the paper employs a different Lyapunov candidate function that incorporates a strictly positive term, the local and remote position error. Some simulations, in free space and interacting with a rigid wall, and experiments, using two nonlinear manipulators, illustrate the performance of the proposed control scheme in the presence of uncertain parameters and variable time-delays. 相似文献
15.
Plagiarism is the misuse of and failure to acknowledge source materials. This paper questions common responses to the apparent increase in plagiarism by students. Internet plagiarism occurs in a context – using the Internet as an information tool – where the relevant norms are far from obvious and models of virtue are difficult to identify and perhaps impossible to find. Ethical responses to the pervasiveness of Internet-enhanced plagiarism require a reorientation of perspective on both plagiarism and the Internet as a knowledge tool. Technological strategies to “catch the cheats” send a “don’t get caught” message to students and direct the limited resources of academic institutions to a battle that cannot be won. More importantly, it is not the right battleground. Rather than characterising Internet-enabled plagiarism as a problem generated and solvable by emerging technologies, we argue that there is a more urgent need to build the background conditions that enable and sustain ethical relationships and academic virtues: to nurture an intellectual community. 相似文献
16.
On the intrinsic value of information objects and the infosphere 总被引：4，自引：3，他引：4
Luciano Floridi 《Ethics and Information Technology》2002,4(4):287-304
What is the most general common set ofattributes that characterises something asintrinsically valuableand hence as subject to some moral respect, andwithout which something would rightly beconsidered intrinsically worthless or even positivelyunworthy and therefore rightly to bedisrespected in itself? Thispaper develops and supports the thesis that theminimal condition of possibility of an entity'sleast intrinsic value is to be identified with itsontological status as an information object.All entities, even when interpreted as only clusters ofinformation, still have a minimal moral worthqua information objects and so may deserve to be respected. Thepaper is organised into four main sections.Section 1 models moral action as an information systemusing the object-oriented programmingmethodology (OOP). Section 2 addresses the question of whatrole the several components constituting themoral system can have in an ethical analysis. If theycan play only an instrumental role, thenComputer Ethics (CE) is probably bound to remain at most apractical, field-dependent, applied orprofessional ethics. However, Computer Ethics can give rise to amacroethical approach, namely InformationEthics (IE), if one can show that ethical concern should beextended to include not only human, animal orbiological entities, but also information objects. Thefollowing two sections show how this minimalistlevel of analysis can be achieved. Section 3 provides anaxiological analysis of information objects. Itcriticises the Kantian approach to the concept ofintrinsic value and shows that it can beimproved by using the methodology introduced in the first section.The solution of the Kantian problem prompts thereformulation of the key question concerningthe moral worth of an entity: what is theintrinsic value of x qua an object constituted by itsinherited attributes? In answering thisquestion, it is argued that entitiescan share different observable propertiesdepending on the level of abstraction adopted,and that it is still possible to speak of moral value even at thehighest level of ontological abstractionrepresented by the informational analysis. Section 4 develops aminimalist axiology based on the concept ofinformation object. It further supports IE's position byaddressing five objections that may undermineits acceptability. 相似文献
17.
土地利用变化驱动力系统分析 总被引：168，自引：18，他引：168
该文应用系统论的观点和方法，对土地利用变化驱动力的整体性、层次性、动态变化和驱动力作用下的土地利用动态进行了深入分析，初步回答了土地利用变化的动力源、驱动力系统内部分力与合力的关系，以及驱动力与土地利用变化之间普遍存在的非线性反馈关系等问题，为土地利用变化动力学研究提供了新的思路。 相似文献
18.
The article treats the problem of “rationality” in learning processes in research policies. The underlying hypothesis is that there are contemporary efforts in research policy-making, which, against views in organisational sociology like “bounded rationality” or “garbage-can”, endeavour to “rationalise” the process of decision-making in research policies. This hypothesis is worked out by taking one example, the setting-up of the “National Centres of Competence in Research” (NCCR) in Switzerland and analyse the processes that have contributed to the acceptance of this funding measure. Our finding is that Switzerland has introduced some “rationalising devices” but that these devices are still insufficiently institutionalised and can be further elaborated. In addition, it is made clear that goal-oriented problem-solving and interests are closely intertwined and cannot be dissociated from another. This may have distorting effects on the rationality of the learning process. It is, nevertheless, a necessary condition in order to learn at all. 相似文献
19.
Charles Cole 《Information processing & management》1998,34(6):709-720
The research examines the notion that the principles underlying the procedure used by doctors to diagnose a patient's disease are useful in the design of “intelligent” IR systems because the task of the doctor is conceptually similar to the computer (or human) intermediary's task in “intelligent information retrieval”: to draw out, through interaction with the IR system, the user's query/information need. The research is reported in two parts. In Part II, an information retrieval tool is described which is based on “intelligent information retrieval” assumptions about the information user. In Part I, presented here, the theoretical framework for the tool is set out. This framework is borrowed from the diagnostic procedure currently used in medicine, called “differential diagnosis”. Because of the severe consequences that attend misdiagnosis, the operating principle in differential diagnosis is (1) to expand the uncertainty in the diagnosis situation so that all possible hypotheses and evidence are considered, then (2) to contract the uncertainty in a step by step fashion (from an examination of the patient's symptoms, through the patient's history and a physical (signs), to laboratory tests). The IR theories of Taylor, Kuhlthau and Belkin are used to demonstrate that these medical diagnosis procedures are already present in IR and that it is a viable model with which to design “intelligent” IR tools and systems. 相似文献
20.
Multi-candidate reduction: Sentence compression as a tool for document summarization tasks 总被引：2，自引：0，他引：2
David Zajic Bonnie J. Dorr Jimmy Lin Richard Schwartz 《Information processing & management》2007,43(6):1549
This article examines the application of two single-document sentence compression techniques to the problem of multi-document summarization—a “parse-and-trim” approach and a statistical noisy-channel approach. We introduce the multi-candidate reduction (MCR) framework for multi-document summarization, in which many compressed candidates are generated for each source sentence. These candidates are then selected for inclusion in the final summary based on a combination of static and dynamic features. Evaluations demonstrate that sentence compression is a valuable component of a larger multi-document summarization framework. 相似文献