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In order to solve the curved-path path following problem for underactuated autonomous underwater vehicle (AUV) in the presence of ocean currents, this paper proposes a modified Line-of-Sight (LOS) path following control strategy. The guidance law is derived based on a new path-following error kinematic model with relative velocities of the vehicle in the Serret-Frenet frame, which makes the AUV produce...
This article analyzed the limitation of stepping motor in current application. The model of hybrid two-phase stepping motor is established. A control system based on fuzzy adaptive control method is designed, and the effectiveness of this method is proved by practical test. The results show that the overshoot of the fuzzy adaptive control is about 5.2% and the adjustment time is about 100 ms.
To ensure the X-rudder autonomous underwater vehicle (AUV) complete the mission in the case of motion actuators failure, a fault-tolerant motion control method based on reconstructive approach is designed in this paper. This fault-tolerant motion control method is composed by double-rudder allocation and triple-rudder allocation, which are based on X rudder's characteristics. One simulation is built...
Harmonic current sources (HCS) that can provide variable-frequency and amplitude output current are widely used in automatic testing of the electrical equipments. Digital repetitive control (RC) can achieve zero steady-state error tracking of any periodic signal with known integer period, hence, it's suitable for harmonic control, but it usually fails to provide precise tracking of variable frequency...
Scalability is a key challenge for digital spiking neural networks (SNN) in hardware. This paper proposes an efficient neuron architecture (ENA) to reduce the silicon area occupied by neurons. As the computation resource (e.g. DSP in FPGAs) is limited for hardware SNNs, the proposed ENA employs a sharing mechanism of computing component at two levels (synapse and neuron) to reduce the occupied resources...
Multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) technology is expected to provide theoretical capacity approaching performance if link adaptation techniques are employed. In this paper, we propose a new link-level estimation technique for maximum likelihood detector. The new proposed technique is able to decouple the modulation level and coding rate from each other...
The proliferation of data-hungry smart electronic devices, such as smartphones and intelligent vehicles, has driven the capacities of current mobile communication systems towards their limits. To tackle this formidable challenge, 3GPP Long Term Evolution has recognized network densification with low-power small cells (SCs) as a key paradigm in the upcoming 5G communication system. In this article,...
In order to realize accurate target tracking for remote operated vehicle, this study has analyzed the tension force from the tether and model based dynamic control strategy. For precise control, the tether effects have been analyzed through a partial differential equation. Each element of the tether has been taken as an elastic body, and the tether has been divided into two parts: in the air and in...
For the popularity of delivering video service over HTTP Adaptive Streaming (HAS) in the mobile network, developing an automatic method to evaluate customers' quality of experience (QoE) for HAS video service in real time is highly desired for network operators and content providers. This paper proposes a novel QoE evaluation strategy for HAS video service based on the specific features of HAS and...
Multiuser communication has been an important research area of underwater acoustic communications and networking. This paper studies the use of adaptive OFDMA in a multiuser downlink scenario, where a central node sends data to multiple distributed nodes simultaneously. The reduction of channel feedback via clustering and quantization is considered, and an interleaved power-bit loading algorithm is...
The formation of Autonomous Underwater Vehicles (AUV) has been increasingly researched with tremendous amount of potential applications, e.g., environment monitoring or surveillance, self-localization and mapping, as well as security patrol. However, acoustic modem is almost the only instrument up to now can effectively work for multi-AUV communications, which is a big limitation in comparing with...
Both TDD and FDD systems obtain their own merits and application limit. As the increasing of service requirement and traffic load, more and more telecommunication systems are operating in both FDD and TDD bands. It is foreseen that convergence of TDD and FDD will be the evolution trend of mobile communication systems. The paper proposes Flexible Duplex to enhance network efficiency and flexibility...
A high-sensitivity, high dynamic range photodetection sensor front-end is presented, suitable for low-cost hand-held food safety systems. This sensor front-end for detecting organophosphorus (OP) compounds incorporates an on-chip deep N-well photodetector, pulse width modulation (PWM), and a folded reference. Designed in a 0.18um process, measurement results show an input optical power dynamic range...
In this paper a fault tolerant GNC system architecture is presented, which meets the high reliability requirements of human-rated Spacecraft. This robust GNC architecture with broadcast communications, wraparound technology and fault handling strategy greatly reduces the effects and occurrence of Byzantine disagreement. This paper proposes a formal analysis approach identifying properties of the fault...
VSC-HVDC is a DC transmission system based on voltage source converter, in which the whole switches are full controlled. The new generation of HVDC transmission technology (VSC-HVDC) are based on VSC consisting of full-controlled devices and Pulse Width Modulation (PWM) technology. VSC-HVDC electromechanical transient model can meet the need of the simulation on large power grid, because electromagnetic...
A wireless 8-channel biopotential acquisition system for capturing electrocardiogram (ECG) using dry electrodes is presented. The ECG system consists of copper electrodes, a micropowered 8-channel custom ASIC, and an off-the-shelf microprocessor and bluetooth radio. Each analog channel of the custom ECG front-end is composed of a chopper-modulated instrumentation amplifier (CMIA) with chopping spike...
In this paper, we consider an underwater data collection problem, where multiple underwater nodes need to send data to one common destination. With the conventional ARQ protocol, the destination requests retransmission from each node individually without any node cooperation. We propose two protocols, selective relay cooperation and dynamic network coded cooperation, utilizing the fact that underwater...
In spite of the recent advances in AUV intelligence techniques, robustly solving their vision perception in ocean environment is still a challenging problem. In this paper, we describe a new framework for object detection and tracking of an AUV, which includes software system and hardware system. It is designed for Vision-based AUV carrying forward looking sonar. The raw data from the sensors are...
Both channel coding over a finite field and linear precoding over a complex field can improve the system performance in wireless fading channels. In this paper, we investigate the potential benefit of linear precoding in a nonbinary LDPC coded underwater acoustic OFDM system. Real precoders of small sizes are selected in different setups, in order to avoid any complexity increase at the receiver....
Effective control of VSC-HVDC connected to weak system is one of the important issues related to the reliable operation of the entire DC system. Firstly, the operation principles of the traditional Vector Current Control are described, and the mechanism of its failure in control due to PLL can't get phase-locked accurately in the transient process when connected to weak system. Then an integrated...
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