1,720,969 research outputs found
PERANCANGAN DAN IMPLEMENTASI SISTEM KENDALI PID SEBAGAI PENGONTROL KECEPATAN ROBOT MOBIL PADA LINTASAN DATAR, TANJAKAN, DAN TURUNAN
Full text linkPengontrolan kecepatan motor DC servo merupakan salah satu permasalahan dalam perkembangan robot mobil. Penggunaan sensor encoder sebagai sensor kecepatan robot mobil yang bergerak pada lintasan bervariasi adalah salah satu input untuk proses otomatisasi itu sendiri. Pengendali PID (Proportional Integral Derivative) adalah pengendali berumpanbalik yang paling popular di dunia industri sebagai pengontrol motor. Dalam tugas akhir ini dilakukan perancangan dan implementasi sebuah robot mobil dengan menggunakan pengendali PID sebagai pengontrol kecepatan. Pencarian nilai Kp, Ki, dan Kd pada penelitian ini ditetapkan dengan metode Ziegler Nichols. Sistem kendali yang dibuat merupakan kendali loop tertutup yang diimplementasikan pada bahasa pemograman Visual Basic 6.0, dan pada mikrokontroler adalah bahasa C. Input sistem kendali PID adalah sensor encoder yang menunjukkan nilai kecepatan aktual robot mobil. Keluaran dari sistem ini berupa PWM yang akan menggerakkan motor dan kecepatan aktual robot akan menjadi sinyal umpan balik ke pengendali. Dari hasil pengujian dan analisa sistem diperoleh hasil bahwa sistem stabil menurut kestabilan routh. Percobaan kontrol motor DC servo dengan pengendali PID menghasilkan galat steady state pada rentang 0% hingga 19.047%
Distributed Robust Synchronization Control of Multiple Heterogeneous Quadcopters with An Active Virtual Leader*
Full text linkThis paper studies leader-following synchronization control of a group of multiple quadrotor unmanned aerial systems (UASs). A robust distributed scheme is developed to maintain the attitude motions of UASs with an active virtual leader. Complicated settings are considered in the design, where the topology is in a directed graph, and only one or some agents are connected to the leader. UASs can have different dynamic parameters. Also, some time-varying disturbances are added to the closed-loop system. A control protocol containing a robust term is proposed to each UAS to achieve asymptotic consensus. A rigorous mathematical proof and numerical example are presented to demonstrate the effectiveness of our scheme
Adaptive Control of Unmanned Aerial Vehicles with Varying Payload and Full Parametric Uncertainties
No full textThis article investigates an adaptive tracking control problem for a six degrees of freedom (6-DOF) nonlinear quadrotor unmanned aerial vehicle (UAV) with a variable payload mass. The changing payload introduces time-varying parametric uncertainties into the dynamical model, rendering a static control strategy no longer effective. To handle this issue, two adaptive schemes are developed to maintain the uncertainties in the translational and rotational dynamics. Initially, a virtual proportional derivative (PD) is designed to stabilize the horizontal position; however, due to an unknown and time-varying mass, an adaptive controller is proposed to generate the total thrust of the UAV. Furthermore, an adaptive controller is designed for the rotational dynamics, to handle parametric uncertainties, such as inertia and external disturbance parameters. In both schemes, a standard adaptive scheme using the certainty equivalence principle is extended and designed. A stability analysis was conducted with rigorous analytical proofs to show the performance of our proposed controllers, and simulations were implemented to assess the performance against other existing methods. Tracking fitness and total control efforts were calculated and compared with closed-loop adaptive tracking control (CLATC) and adaptive sliding mode control (ASMC). The results indicated that the proposed design better maintained UAV stability
Adaptive Consensus of Nonlinearly Parameterized Multi-Agent Systems
No full textThis letter studies the distributed adaptive consensus problem for multi-agent systems (MASs) subject to nonlinearly parameterized uncertainties. In the existing research, an adaptive consensus scheme was developed for the same scenario but under the assumption that the uncertainties must be linearly parameterized in their unknown parameters. In this letter, the assumption is removed by using a novel distributed adaptive update law, which makes the scheme applicable for more general nonlinear MASs. This letter contains a general design paradigm using the certainty equivalence principle and specific implementation of it on nonlinear second-order MASs. The results are supported by rigorous mathematical analysis and numerical simulation.</p
Adaptive Consensus of Nonlinearly Parameterized Multi-Agent Systems
No full textThis paper studies the distributed adaptive consensus problem for multi-agent systems (MASs) subject to nonlinearly parameterized uncertainties. In the existing research, an adaptive consensus scheme was developed for the same scenario but under the assumption that the uncertainties must be linearly parameterized in their unknown parameters. In this paper, the assumption is removed by using a novel distributed adaptive update law, which makes the scheme applicable for more general nonlinear MASs. The paper contains a general design paradigm using the certainty equivalence principle and specific implementation of it on nonlinear second-order MASs. The results are supported by rigorous mathematical analysis and numerical simulation
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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