scholarly journals Optimal Damping Concept Implementation for Marine Vessels’ Tracking Control

2021 ◽  
Vol 9 (1) ◽  
pp. 45
Author(s):  
Evgeny I. Veremey
Keyword(s):  
Tracking Control ◽  
Control Synthesis ◽  
Synthesis Methods ◽  
Optimization Approach ◽  
Central Attention ◽  
Closed Loop Systems ◽  
Optimal Damping ◽  
Time Regime ◽  
And Performance ◽  
Marine Vessels

This work presents the results of studies related to the design of stabilizing feedback connections for marine vessels moving along initially given trajectories. As is known, in mathematical formalization, this question leads to a problem of tracking control synthesis for nonlinear and non-autonomous plants. To provide desirable stability and performance features of the closed-loop systems to be synthesized, it is appropriate to use an optimization approach. Unlike the known synthesis methods, which are usually used within the framework of this approach, it is proposed to implement the optimal damping concept first developed by V.I. Zubov in the early 60s of the last century. Modern interpretation of this concept allows constructing numerically effective procedures of control law synthesis taking into account its applicability in a real-time regime. Central attention is focused on the questions connected with practical adaptation of the optimal damping methods for marine control systems. The operability and effectiveness of the proposed approach are illustrated by a practical example of tracking control design.

scholarly journals On practical application of Zubov’s optimal damping concept

2020 ◽  
Vol 16 (3) ◽  
pp. 293-315
Author(s):  
Evgeny I. Veremey ◽  
Keyword(s):  
Practical Implementation ◽  
Optimization Approach ◽  
Practical Application ◽  
Closed Loop System ◽  
Control Laws ◽  
Optimal Damping ◽  
New Ideas ◽  
And Performance ◽  
Essential Connection ◽  
Significant Attention

This article presents some new ideas connected to nonlinear and nonautonomous control laws based on the application of an optimization approach. There is an essential connection between practical demands and the functionals to be minimized. This connection is at the heart of the proposed methods. The discussion is focused on the optimal damping concept first proposed by V. I. Zubov in the early 1960’s. Significant attention is paid to various modern aspects of the optimal damping theory’s practical implementation. Emphasis is given to the specific choice of the functional to be damped to provide the desirable stability and performance features of a closed-loop system. The applicability and effectiveness of the proposed approach are confirmed by an illustrative numerical example.

scholarly journals A 4-DOF Upper Limb Exoskeleton for Physical Assistance: Design, Modeling, Control and Performance Evaluation

2021 ◽  
Vol 11 (13) ◽  
pp. 5865
Author(s):  
Muhammad Ahsan Gull ◽  
Mikkel Thoegersen ◽  
Stefan Hein Bengtson ◽  
Mostafa Mohammadi ◽  
Lotte N. S. Andreasen Struijk ◽  
...  
Keyword(s):  
Upper Limb ◽  
Tracking Control ◽  
Degrees Of Freedom ◽  
Control Method ◽  
Mechanical Design ◽  
Trajectory Tracking Control ◽  
Upper Limb Exoskeleton ◽  
And Performance ◽  
Physically Disabled People ◽  
Human Upper Limb

Wheelchair mounted upper limb exoskeletons offer an alternative way to support disabled individuals in their activities of daily living (ADL). Key challenges in exoskeleton technology include innovative mechanical design and implementation of a control method that can assure a safe and comfortable interaction between the human upper limb and exoskeleton. In this article, we present a mechanical design of a four degrees of freedom (DOF) wheelchair mounted upper limb exoskeleton. The design takes advantage of non-backdrivable mechanism that can hold the output position without energy consumption and provide assistance to the completely paralyzed users. Moreover, a PD-based trajectory tracking control is implemented to enhance the performance of human exoskeleton system for two different tasks. Preliminary results are provided to show the effectiveness and reliability of using the proposed design for physically disabled people.

Advances in MXene Films: Synthesis, Assembly, and Applications

2021 ◽  
Author(s):  
Xiaohua Li ◽  
Feitian Ran ◽  
Fan Yang ◽  
Jun Long ◽  
Lu Shao
Keyword(s):  
Spin Coating ◽  
Reaction Mechanisms ◽  
Membrane Separation ◽  
Synthesis Methods ◽  
Metal Carbides ◽  
Max Phases ◽  
Practical Applications ◽  
Coating Methods ◽  
And Performance ◽  
Important Form

AbstractA growing family of two-dimensional (2D) transition metal carbides or nitrides, known as MXenes, have received increasing attention because of their unique properties, such as metallic conductivity and good hydrophilicity. The studies on MXenes have been widely pursued, given the composition diversity of the parent MAX phases. This review focuses on MXene films, an important form of MXene-based materials for practical applications. We summarized the synthesis methods of MXenes, focusing on emerging synthesis strategies and reaction mechanisms. The advanced assembly technologies of MXene films, including vacuum-assisted filtration, spin-coating methods, and several other approaches, were then highlighted. Finally, recent progress in the applications of MXene films in electrochemical energy storage, membrane separation, electromagnetic shielding fields, and burgeoning areas, as well as the correlation between compositions, architecture, and performance, was discussed.

Adaptive attitude-tracking control of spacecraft considering on-orbit refuelling

2020 ◽  
pp. 014233122097313
Author(s):  
Yiqi Xu
Keyword(s):  
Tracking Control ◽  
Closed Loop ◽  
Closed Loop System ◽  
Tracking Errors ◽  
Attitude Tracking ◽  
Control Scheme ◽  
Inertia Model ◽  
And Performance ◽  
Attitude Tracking Control ◽  
The Stability

This paper studies the attitude-tracking control problem of spacecraft considering on-orbit refuelling. A time-varying inertia model is developed for spacecraft on-orbit refuelling, which actually includes two processes: fuel in the transfer pipe and fuel in the tank. Based upon the inertia model, an adaptive attitude-tracking controller is derived to guarantee the stability of the resulted closed-loop system, as well as asymptotic convergence of the attitude-tracking errors, despite performing refuelling operations. Finally, numerical simulations illustrate the effectiveness and performance of the proposed control scheme.

scholarly journals Online Optimal Control of Robotic Systems with Single Critic NN-Based Reinforcement Learning

Complexity ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Xiaoyi Long ◽  
Zheng He ◽  
Zhongyuan Wang
Keyword(s):  
Optimal Control ◽  
Reinforcement Learning ◽  
Tracking Control ◽  
Learning Algorithm ◽  
Tracking Error ◽  
Adaptive Dynamic Programming ◽  
Robotic Systems ◽  
Control Synthesis ◽  
Optimal Tracking ◽  
Optimal Tracking Control

This paper suggests an online solution for the optimal tracking control of robotic systems based on a single critic neural network (NN)-based reinforcement learning (RL) method. To this end, we rewrite the robotic system model as a state-space form, which will facilitate the realization of optimal tracking control synthesis. To maintain the tracking response, a steady-state control is designed, and then an adaptive optimal tracking control is used to ensure that the tracking error can achieve convergence in an optimal sense. To solve the obtained optimal control via the framework of adaptive dynamic programming (ADP), the command trajectory to be tracked and the modified tracking Hamilton-Jacobi-Bellman (HJB) are all formulated. An online RL algorithm is the developed to address the HJB equation using a critic NN with online learning algorithm. Simulation results are given to verify the effectiveness of the proposed method.

scholarly journals Carbon-Based Catalysts for Biodiesel Production—A Review

2020 ◽  
Vol 10 (3) ◽  
pp. 918 ◽  
Author(s):  
Jack Clohessy ◽  
Witold Kwapinski
Keyword(s):  
Heterogeneous Catalysts ◽  
Catalyst Activity ◽  
High Surface ◽  
High Surface Area ◽  
Acid Catalyst ◽  
Biodiesel Production ◽  
Catalyst Characterization ◽  
Synthesis Methods ◽  
And Performance ◽  
Carbon Based

In recent years, a new class of superior heterogeneous acid catalyst for biodiesel production has emerged. These catalysts offer advantages over their predecessors such as high surface area, elevated acid site density, enhanced catalyst activity, good operation stability and relevant economic affordability in an environmentally friendly frame. This review was concerned with carbon-based solid acid (CBAS) catalysts derived from both carbohydrate and pyrolysis products. A series of CBASs with various origins such as D-glucose, sucrose, starch, cellulose and vegetable oil asphalt, converted to char and sulphonated, have been explored as potential heterogeneous catalysts. Catalyst preparation and synthesis methods were briefly summarized. Catalyst characterization and performance for biofuels related reactions were elucidated, identifying potential research applications. Three catalysts in particular were identified as having potential for industrial application and requiring further research.

scholarly journals Decentralized Suboptimal State Feedback Integral Tracking Control Design for Coupled Linear Time-Varying Systems

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Mohamed Sadok Attia ◽  
Mohamed Karim Bouafoura ◽  
Naceur Benhadj Braiek
Keyword(s):  
Tracking Control ◽  
State Feedback ◽  
Linear Time ◽  
Least Square ◽  
Control Synthesis ◽  
Operational Matrices ◽  
Control Input ◽  
Time Varying ◽  
State Equations ◽  
Integral Control

In this paper, a suboptimal state feedback integral decentralized tracking control synthesis for interconnected linear time-variant systems is proposed by using orthogonal polynomials. Particularly, the use of operational matrices allows, by expanding the subsystem input states and outputs over a shifted Legendre polynomial basis, the conversion of time-varying parameter differential state equations to a set of time-independent algebraic ones. Hence, optimal open-loop state and control input coefficients are forwardly determined. These data are used to formulate a least-square problem, allowing the synthesis of decentralized state feedback integral control gains. Closed-loop asymptotic stability LMI conditions are given. The proposed approach effectiveness is proved by solving a nonconstant reference tracking problem for coupled inverted pendulums.

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