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This paper presents an analytic, numerical and experimental study of air damping behavior of lateral-axis vibratory wheel gyroscopes (VWG) in vacuum range of 0.008Pa to 10Pa. An analytic model is proposed for slide film damping in drive mode, and a Reynolds equation solved by a finite-difference method is employed for squeeze film damping in sense mode. The developed models are verified by experiment...
In order to obtain accurate single-phase-to-ground zero-sequence current signal to improve the accuracy of fault line selection, a new data acquisition method—compressed sensing theory, was applied to single-phase-to- ground fault line selection of distribution network. A new method of fault line selection based on Bayesian compressed sensing theory was proposed. The method used compressed sampling...
Intelligent prosthetics aim to provide a communication channel between disabled people and external world. Among them, walking-assistive device to help people with lower-limb disability attracts attention but still limited by unnatural gait or lack accurate real-time control. Here we studied the coupling between the upper limbs and the lower limbs since the whole body actually involved during walking...
The introduction of automation in cyber-physical systems (CPS) has raised major safety and security concerns. One attack vector is the sensing unit whose measurements can be manipulated by an adversary through attacks such as denial of service and delay injection. To secure an autonomous CPS from such attacks, we use a challenge response authentication (CRA) technique for detection of attack in active...
This paper presents a total least-squares (TLS) algorithm for target motion analysis (TMA) using power, bearing and time-difference of arrival (TDOA) measurements. Under the small noise condition, we linearize the power, bearing and TDOA measurement equations and derive a new error-in-variable model. Then a TLS method is proposed to solve the power-bearing-TDOA TMA problem. Simulation results show...
GyroWheel is an innovative device that combines the actuating capabilities of the control moment gyro with the rate sensing capabilities of the tuned rotor gyro by using a spinning flex-gimbal system. For a 3-DOF GyroWheel rotor with high spinning velocity, the uneven mass distribution, called unbalance, is inevitable which leads to unexpected vibration and uncertain dynamics, which needs to be corrected...
Freeway traffic state estimation is the major assurance of traffic management and control. This paper addresses a traffic density estimator for Beijing third ring freeway. First, we apply a new modeling method called Dynamic Graph Hybrid Automata (DGHA) to express the traffic dynamics and the evolution law of the freeway network by piecewise-linear. On this basis, it is feasible to use a open source...
Abstract-An overwhelming majority of the existing work on spectrum sensing assumes that secondary users (SUs) are stationary. However, mobility is an essential property of wireless networks. In this paper, we analyze the performance of spectrum sensing by mobile SUs. Four performance metrics, i.e. detection, miss detection, false alarm and error probabilities, are thoroughly investigated. A critical...
The Internet of Things (IoT) has been widely applied in sensing systems, which connect various sensors and gather their information. Data fusion, which is to integrate multiple data representing the same real-world object into a consistent and accurate representation, is an important issue. Most of existing approaches of data fusion involve various analytical procedures whose high computational complexity...
Abstract-An overwhelming majority of existing work on soft-decision cooperative spectrum sensing makes the assumption that secondary users (SUs) in cognitive radio networks (CRNs) are stationary. Considering that mobility is an essential property of wireless networks, we analyze the detection performance of soft-decision sensing by mobile SUs. Then, a data fusion rule is proposed aiming at mobile...
This paper introduces a self-designed wearable inertial measurement unit (IMU-BMSJv2) and the calibration of its tri-axial accelerometers. We compare two popular accelerometer calibration approaches, the classical method (attitude dependent) and auto calibration method (attitude independent). Both these two calibration methods have been applied for the calibration of the self-designed IMU-BMSJv2;...
There are two challenges when performing cooperative spectrum sensing considering security issues in cognitive radio networks. One is to distinguish honest secondary users in the fading area with malicious cognitive users and the other is how to stimulate cognitive users to take part in cooperative spectrum sensing so that the whole system performance could be enhanced. In this paper, we propose a...
Prediction of interaction force between human and contacting environment has always been an important issue for such as robot control and clinical treatment. Although force/torque sensors can provide direct and precise measurement results, in many cases it is inconvenient to attach these sensors on the environment surface or on human beings. The purpose of this paper is to propose a prediction method...
Based on the recently emerging compressive sensing theory, the paper proposes an ultra-low power multichannel data conversion system whose architecture is almost as simple as a single SAR ADC. The proposed architecture is capable of simultaneously converting multi-channel sparse signals while running at the Nyquist rate of only one channel. A chip is fabricated in a 0.13μm CMOS process. Operating...
Predicting the licensed or primary user (PU) channel state future has been widely investigated in the recent literature, this study introduce a new approach for predicting PU channel state based on time series and hidden Markov model (HMM). In this new approach we model the primary user channel state detection sequence, which can be represented by; PU channel “idle” or “occupied” as a time series...
Heave compensation system is a new type of automatic control system accompanied by increasing offshore operation; its main purpose is to ensure marine equipment operation not affected by undulating limits, which can normally work under adverse sea conditions. This paper proposes a detection system with high performance, high precision control algorithm of the active heave compensation system, through...
The problem of estimating speaker location in smart conference video system is considered. In this paper, a four-microphone cross array is constructed to localize speakers with Time Difference of Arrival (TDoA) measurements based on hyperbola model. The time delay was calculated using Generalized Cross Correlation (GCC)algorithm. A practical test system was build to confirm the feasibility of the...
The sensing data is usually transmitted simultaneously from the sensor to the controller in conventional control systems. However, in networked control systems it is possible that a set of sensing data is transmitted via multiple separate data packets due to the multiple, geographically dispersed sensors. This scenario, referred to as “multi-packet transmission”, brings to the system different delays...
In this study, a nonlinear model is developed to connect a biomimetic autonomous underwater vehicle (BAUV) with human cardiovascular system. The BAUV with sensors and a compliant tail is capable to perform Carangiform locomotion. To make the tail of the BAUV perform rhythmic motion, a nonlinear feedback torque is applied to the tail equation to construct a self-excited oscillator. Besides, a system...
One challenge in delay tolerant networks (DTNs) is efficient routing, as the lack of contemporaneous end-to-end paths makes conventional routing schemes inapplicable. Many existing DTN routing protocols adopt multi-copy replication and/or are incognizant of mobility models. Hence they are not suitable for networks with extremely stringent resources and time-varying mobility models such as underwater...
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