In this paper, we propose an adaptive fault-tolerant visual control scheme for robotic manipulators with possible actuator failures in an uncalibrated environment. Most existing visual control approaches for robot sys...
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In this paper, we propose an adaptive fault-tolerant visual control scheme for robotic manipulators with possible actuator failures in an uncalibrated environment. Most existing visual control approaches for robot system do not take into account actuator failures, which may prominently affect the transient performance of the system in practice. In order to moderate the detrimental and adverse effects of actuator failures on the system, a new adaptive algorithm is proposed to compensate stuck-type failures occurred in actuators. Moreover, by proposing a decoupling method, the uncertain parameter model of actuator failure is successfully separated from the dynamics model while the two models are coupled in most existing results [e.g., (Rugthum and Tao in Robotica 34(7):1529-1552, 2016;Rugthum in: International conference on engineering, applied sciences, and technology (ICEAST), pp 1-4, 2018)]. And the stability of the dynamic system and the convergence of the image error are proved by the Lyapunov analysis method. Finally, the effectiveness of the proposed control scheme is verified by comparing and analysing the tracking performance of the 3-DOF manipulator under different failure parameters.
The Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) is an integrated algorithm employed in the Enhanced Distributed Channel Access (EDCA) in the IEEE 802.11p protocol. CSMA/CA manages the access of pa...
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ISBN:
(纸本)9781509003051
The Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) is an integrated algorithm employed in the Enhanced Distributed Channel Access (EDCA) in the IEEE 802.11p protocol. CSMA/CA manages the access of packets to the medium and its main role is to avoid collisions among them. An essential process of CSMA/CA is the backoff period in which the packets has to wait for a random number of Time Slots (TS) before attempting to access the medium. The backoff operation is based on a simple deterministic approach that does not consider the status of the medium at the time of transmission. In this paper, we propose an adaptive Backoff algorithm (ABA). ABA is based on a probabilistic approach that takes into account the current situation of the medium. ABA is calculated as a function of the packets probability of collision. We present two algorithms ABA1 and ABA2, the function of the former is directly proportional to the collision probability however the function of the latter is exponentially dependent on the collision probability. We develop a Markov-based analytical model to evaluate ABA1 and ABA2, and study the performance of each system.
In this article, a distributed adaptive continuous-time optimization algorithm based on the Laplacian-gradient method and adaptive control is designed for resource allocation problem with the resource constraint and t...
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In this article, a distributed adaptive continuous-time optimization algorithm based on the Laplacian-gradient method and adaptive control is designed for resource allocation problem with the resource constraint and the local convex set constraints. In order to deal with local convex sets, a distance-based exact penalty function method is adopted to reformulate the resource allocation problem instead of the widely used projection operator method. By using the nonsmooth analysis and set-valued LaSalle invariance principle, it is proven that the proposed algorithm is capable of solving the nonsmooth resource allocation problem. Finally, two simulation examples are presented to substantiate the theoretical results.
Full-duplex wireless communication system transmits and receives signals in a same frequency band and at a same time, which solves the problem of the low using efficiency of limited radio spectrum resource, and double...
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Full-duplex wireless communication system transmits and receives signals in a same frequency band and at a same time, which solves the problem of the low using efficiency of limited radio spectrum resource, and doubles the channel capacity. However, it also brings a new problem that the full-duplex node will generate a strong self-interference signal. And to deal with the self-interference signal, using existing negative selfinterference cancellation and analog self-interference cancellation technology are not enough, effective digital selfinterference cancellation is needed for further cancellation. This paper proposes an optimized adaptive algorithm of digital selfinterference cancellation based on improved variable step. By using a iteration threshold, we establish a new nonlinear relationship between the step factor and the error signal, which overcomes the slow change problem when the error signal is getting closed to zero, and accelerates the convergence rate.
Pipelined analog-to-digital converters (ADCs) are fundamental components of various signal processing systems requiring high sampling rates and a high linearity. Over the past years, calibration techniques have been i...
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Pipelined analog-to-digital converters (ADCs) are fundamental components of various signal processing systems requiring high sampling rates and a high linearity. Over the past years, calibration techniques have been intensively investigated to increase the linearity. In this brief, we propose an equalization-based calibration technique which does not require knowledge of the ADC input signal for calibration. For that, a test signal and a scaled version of it are fed into the ADC sequentially, while only the corresponding output samples are used for calibration. Several test signal sources are possible, such as a signal generator (SG) or the system application (SA) itself. For the latter case, the presented method corresponds to a background calibration technique. Thus, slowly changing errors are tracked and calibrated continuously. Because of the low computational complexity of the calibration technique, it is suitable for an on-chip implementation. Ultimately, this brief contains an analysis of the stability and convergence behavior as well as simulation results.
A actuator fault estimation algorithm based on adaptive iterative learning is proposed for a class of nonlinear periodic systems with actuator fault and disturbances. Firstly, the proposed method designs a state obser...
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ISBN:
(纸本)9789881563804
A actuator fault estimation algorithm based on adaptive iterative learning is proposed for a class of nonlinear periodic systems with actuator fault and disturbances. Firstly, the proposed method designs a state observer and a fault estimator based on adaptive iterative learning. The Lyapunov stability theory and the optimization theory are employed to prove the convergence of the method. Then the LMI toolbox is utilized to obtain the results of the observer gain matrix and fault estimator parameter matrix. The method combines the iterative learning strategy with the adaptive algorithm, and utilizes not only the state error signals of the last iteration learning, but also the output error signals of this time. It makes the estimated fault approximate to the real fault gradually and realizes the accurate estimation of the time-varying fault and the intermittent fault. Finally, the validity and accuracy of the proposed method are verified by the simulation of a single-link robotic arm mold.
Since Bluetooth5 standard released in 2016, its usage in commercial electronic products has been increased rapidly and substantially. Comparing to BLE 4.2, Bluetooth5 supports three PHY modes, respectively 2M, 1M and ...
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ISBN:
(纸本)9781728184807
Since Bluetooth5 standard released in 2016, its usage in commercial electronic products has been increased rapidly and substantially. Comparing to BLE 4.2, Bluetooth5 supports three PHY modes, respectively 2M, 1M and Coded PHY mode, providing a higher throughput and a wider range. Whereas there is a trade-off between its throughput and coverage. When the connection is established, the PHY mode is commonly pre-configured and fixed. This rigid design limits the flexibility in offering dynamic throughput and coverage. Therefore, we propose a method termed AptBLE, that switches the PHY mode in Bluetooth5 adaptively by considering the Received Signal Strength Indicator (RSSI) level. Specifically, we optimise the RSSI threshold for different PHY modes using the K-means clustering algorithm. Moreover, based on AptBLE, we further enable the Data Length Extension (DLE) feature and term the improved method as AptBLEM. We implement AptBLE (M) on the boards and test in indoor environment. The experimental results show that, AptBLE is more flexible, robust and outperforms the original fixed PHY mode in terms of throughput and transmission range. Furthermore, AptBLEM can triple the throughput than AptBLE, with a maximum throughput value in 1035Kbps and 42m range in indoor environment.
The accuracy of cylinder air charge direct measurement affects air-fuel ratio (AFR) control performance and exhaust emissions of internal combustion engines, especially during the transient response. In lean combustio...
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The accuracy of cylinder air charge direct measurement affects air-fuel ratio (AFR) control performance and exhaust emissions of internal combustion engines, especially during the transient response. In lean combustion control, the combustion variation is higher than the normal combustion. Accurate air charge estimation is crucial in this combustion mode. Therefore, the methodology for the improvement of cylinder air charge estimation is required. With the effective air charge estimation method, the feedforward control of fuel injection can be precisely performed. This paper studies the performance of the adaptive air charge estimation algorithm on the lean operation mode. The results show that the applied algorithm is robust and has high efficiency for the cylinder air charge estimation. Copyright (C) 2021 The Authors.
Wi-Fi fingerprinting is the most popular indoor positioning method today, representing received signal strength (RSS) values as vector-type fingerprints. Passive fingerprinting, unlike the active fingerprinting method...
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Wi-Fi fingerprinting is the most popular indoor positioning method today, representing received signal strength (RSS) values as vector-type fingerprints. Passive fingerprinting, unlike the active fingerprinting method, has the advantage of being able to track location without user participation by utilizing the signals that are naturally emitted from the user's smartphone. However, since signals are generated depending on the user's network usage patterns, there is a problem in that data are irregularly collected according to the patterns. Therefore, this paper proposes an adaptive algorithm that shows stable tracking performances for fingerprints generated at irregular time intervals. The accuracy and stability of the proposed tracking method were verified by experiments conducted in three scenarios. Through the proposed method, it is expected that the stability of indoor positioning and the quality of location-based services will improve.
In this paper,based on the velocity-pressure formulation of the Stokes eigenvalue problemin d-dimensional case(d=2,3),we propose amultigrid discretization of discontinuous Galerkin method using P_(k)-P_(k)-1 element(k...
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In this paper,based on the velocity-pressure formulation of the Stokes eigenvalue problemin d-dimensional case(d=2,3),we propose amultigrid discretization of discontinuous Galerkin method using P_(k)-P_(k)-1 element(k≥1)and prove its a priori error *** also give the a posteriori error estimators for approximate eigenpairs,prove their reliability and efficiency for eigenfunctions,and also analyze their reliability for *** implement adaptive calculation,and the numerical results confirm our theoretical predictions and show that our method is efficient and can achieve the optimal convergence order O(do f-2k/d).
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