Search

In this paper, a novel approach for trajectory tracking of a mobile manipulator mounted on an unmanned surface vehicle (USV) is proposed. The main contributions of the paper are as follows: (1) The USV and the manipulator are modeled systematically with respect to the interactions between the two subsystems. (2) The coupling dynamics between the USV and the manipulator are considered as a part of unknown complex disturbance and estimated by the fuzzy approximation method. (3) Coordination control scheme based on fuzzy approximation is designed to handle constraint relationships between the USV and the manipulator such that the tracking errors in the both two subsystems can converge to zero domain. Simulation results demonstrate the tracking effectiveness and efficiency of the proposed control algorithm.

A desktop intelligent soccer robot match system based on 3D printing technology is designed.we use 3D printing technology to make soccer robot body, and open-source hardware like Arduino to make soccer robot control system. The four-wheel soccer robot controlled by Bluetooth is designed by using 3D printing technology. In an internet of things smart arena, the robot is controlled by mobile phone via Bluetooth, catch the football and shoot into the opponent’s goal. The children in the game scan the QR code and install the APP, choose the team to join, participate in the game, and the score more goals to win. We also designed an intelligent table football field based on the Internet of Things technology with automatic referring and scoring, which combines desktop game and the innovation of robot game. It has the advantages of low cost and strong interest.

The vehicle density determines the frequency of information congestion and collision in VANETs, and affects the quality of communication. Cluster management of vehicle nodes can effectively improve communication efficiency of the network. A clustering framework based on changes in vehicle density and an improved k-means clustering algorithm based on vehicle movement characteristics are proposed in this paper. According to the change of vehicle density, nodes are dynamically clustered, in some cases MSCNs(Mobile Secondary Computing Node) are selected and virtual computing areas are divided. The simulation on NS3 shows that the proposed improved k-means-based adaptive clustering algorithm has strong stability and high communication efficiency.

Unmanned Ariel Vehicle(UAV) has been widely used in the edge computing network. Owing to its line-of-sight communication ability and mobility, it has offered task offloading service and some task computation for mobile devices(MDs). Nowadays, as high-intensity calculation application develops rapidly, maximizing the size of offloaded tasks is necessary for meeting the users' experience in applications. In this context, our paper takes research on how to deploy UAVs at the most proper place to offer task offloading with TDMA protocol. Specifically, we will optimize the task offloading number in the MDs-UAV system by combining the location of UAVs, the task computation capacity of UAV, and the MDs-UAV associations in a certain time. We prove that the joint UAV deployment and task computation problem is NP-hard, and use a greedy algorithm to optimize the result. Compared with randomly selected method, our simulation shows that the greedy algorithm performs greatly and the deployment of UAVs are sensible. We believe that this idea will improve the system tasks processing rate and Quality of Experience(QoE) of mobile users.

With the rapid technology development in autonomous navigation of Unmanned Aerial Vehicles (UAVs) and robust object detection based on deep neural networks, the field of traffic analysis through aerial video has attracted widespread attention. In this paper, we investigate the problems of ground vehicle tracking and speed estimation using aerial view videos. At the first stage, the vehicle detection is performed through the YOLOv3 network, which is the state-of-the-art object detector. Then, a tracking-by-detection method is designed to tracking the traffic vehicles. Furthermore, in order to estimate the vehicle speed in traffic while the UAV navigating in different heights, the least square algorithm is utilized to fit the measurement data and determine the power function mapping relationship between the vehicle pixel distance and the actual distance, which further improves the accuracy of speed estimation effectively.

The Digital Twin (DT) is one of the main concepts associated to the Industry 4.0 wave. This term is more and more used in industry and research initiatives. DT provides virtual representations of systems along their lifecycle, and should be used in autonomous driving test. In this paper, we have come out with using digital twin to test autonomous driving in a finite environment: based on the virtual simulation test environment of automatic driving, the test of real automatic driving vehicles for the virtual complex road scene can be realized by using the digital twin mapping.

An iteration-phase retrieval method for quiet zone of compact antenna test ranges is proposed in this paper. The missing phase can be attained with field amplitude-only data on two parallel planes and initial random spatial phase processed interactively by an algorithm. Thus, a combined Gerchberg–Saxton and hybrid input–output (GS/HIO) algorithm is considered. In order to avoid aliasing effect, the size of data on each plane are enlarged with the same number of zeros padded before iteration, and then reduced into the original size after the propagation of angular spectrum. The required data, sampled at 220GHz with half-wavelength, are obtained through GRASP simulation software. The validity of the method is verified with MATLAB. The results show that the GS/HIO algorithm with zero padded has more effective than without zero padded. The maximum phase deviation in quiet zone (±0.35 m) of x and y-axis is less than 0.72°.

Radio astronomy receiver development is focusing on increasing the field of view and bandwidth in tandem with the exponential increase in data volumes permitted by signal processing. We present recent receiver and signal processing developments from CSIRO and FAST.

The noise emitted from distribution transformer often disturbs the normal life of people around it, hence it is necessary to research the noise characteristics of the vegetable insulating oil transformer. The characteristic of noise emitted by the 10KV vegetable insulating oil transformer under the condition with no load and different loads were tested in a spacious HV testing hall. As a comparison, the vegetable insulating oil in transformer was replaced by mineral insulating oil, and the noise of the transformer filled with mineral oil has also been measured in the same environment. The experiment results demonstrated that A-weighted sound pressure level of noise emitted from the transformer filled with vegetable insulating oil is about 5~6dB lower than that of noise emitted from the transformer filled with mineral insulating oil. Combined with the characteristics of insulating oil and the classical calculation formula of absorption coefficient, the sound absorption coefficient calculating formula of insulating oil has been derived. Though the calculation, it was found that the sound absorption coefficient of FR3 is about 2 times higher than that of mineral insulating oil. Thus vegetable insulating oil FR3 can reduce the transformer noise better than mineral insulating oil.

Ageing assessment of paper insulation is important to safe operation, condition based maintenance, and replacement of power transformers. This paper investigated the effect of oil replacement (OR) upon ageing assessment of paper insulation based on dispersion staining colours of cellulose fibres in oil. Accelerated thermal ageing experiments were conducted for oil-paper specimens for different durations and OR was conducted at different ageing stages. Degree of polymerization (DP) of paper and 2-furaldehyde (2-FAL) in oil were measured, and the dispersion staining colours of cellulose fibres were observed. DP of paper was predicted using traditional ageing marker 2-FAL and proposed ageing marker, i.e., primary colour ratio based Mahalanobis distance (PCR-MD) of (r, b) points. Results show that OR has little effect on DP of paper while it can results in substantial loss of carbon oxides and 2-FAL in oil. The OR has limited effect on Mahalanobis distance of (r, b) points. The prediction errors of DP with ageing marker PCR-MD is smaller than those with 2-FAL, which implies that the proposed ageing marker PCR-MD can be applied to ageing assessment of paper insulation that undergoes OR with accepted error level.

Application offloading is an effective method for extending the battery life of mobile devices by executing some tasks of a mobile application in the cloud. This paper provides an energy-optimal transmission rate scheduling scheme executed at mobile devices in application offloading process. Our objective is to conserve energy for the mobile devices by optimally adjusting the transmission rate of mobile applications. Instead of adopting the widely used dynamic programming (DP) algorithm, we propose a modified Lyapunov optimization method. The method is obtained by modifying the Lyapunov optimization method to adapt it for mobile cloud computing scenario. Compared to DP algorithm which is in need of the statistical information of the stochastic wireless channels, the most important advantage of our proposed method is that it can obtain a closed-form expression for transmission rate only according to the actual measurement of the channel gain in each time slot and thereby can avoid the deviation from prediction of the channel gain in future time slots. The numerical results demonstrate that our proposed method can save about 30% of the energy compared to DP algorithm.

The collision avoidance problem of autonomous ships is analyzed in this paper. Firstly, the background and the difficulties are reviewed. Then an improved artificial potential field method is designed to solve the collision avoidance problem of unmanned ships, and the system characteristics are investigated. Finally, simulation results demonstrate the ship's control effectiveness in the obstacle environment.

The cooperative tracking control problem of autonomous vessels is analyzed in this paper. Firstly, we capture the properties of motion constraints of marine vessels. We relate these constraints to previous analysis to suggest ways that they can be bounded in practice. Then a feedback-linearization tracking method and a sliding mode controller are designed respectively to solve the consensus problem of underactuated vessels, and the stability of the system is discussed. Finally, simulation results demonstrate the tracking effectiveness of the marine vessels.

The development of matrix completion theory provides new approaches for data gathering in Wireless Sensor Networks (WSN). The existing matrix completion algorithms for WSN mainly consider how to reduce the sampling number without considering the real-time performance when recovering the data matrix. In order to guarantee the recovery accuracy and reduce the recovery time consumed simultaneously, we propose a new Augmented Lagrange Multiplier (ALM) algorithm to recover the weather monitoring data. A large amount of experiments have been carried out to investigate the performance of the proposed ALM algorithm by using different parameter settings, different sampling rates and sampling models. In addition, we compare the proposed ALM algorithm with some existing algorithms in the literature. Experimental results show that the ALM algorithm can obtain better overall recovery accuracy with less computing time, which demonstrate that the ALM algorithm is an effective and efficient approach for recovering the real world weather monitoring data in WSN.

A novel cooperative tracking method for multiple vessels is presented. The dynamics of underactuated vessels are described firstly, we are especially interested in situations for which there are environmental disturbances induced by wind, waves and ocean currents. Then tracking errors are analyzed and a sliding mode tracking controller is designed to solve the consensus problem of underactuated vessels, and the stability of the system is discussed. Some convincing simulation results are provided to illustrate the theoretical results.

In this paper, we propose an acceleration-based human activity recognition method using popular deep architecture, Convolution Neural Network (CNN). In particular, we construct a CNN model and modify the convolution kernel to adapt the characteristics of tri-axial acceleration signals. Also, for comparison, we use some widely used methods to accomplish the recognition task on the same dataset. The large dataset we constructed consists of 31688 samples from eight typical activities. The experiment results show that the CNN works well, which can reach an average accuracy of 93.8% without any feature extraction methods.

A novel formation control method for multiple unmanned underactuated ships is presented based on terminal sliding mode control. At first, a directed topology graph is used to describe the information interaction between the ships and its neighbors, then a novel curved-dynamic coordinates is constructed, which is used to the consensus reference for the formation motion. Under the formation coordinates, a local-to-global terminal sliding controller is designed to keep the relative pose of the dynamic unmanned ships at last.

The secondary optics design is a critical issue for the light distribution and output efficiency of the LED street light. Traditional light distribution methods are simple but difficult to get high energy efficiency and illumination uniformity together. In this paper, the adoption of the unsymmetrical freeform surface lens can obtain a rectangular light distribution pattern just cover the road with little waste of light. In this paper, an unsymmetrical freeform optic lens is designed which is combining with theory of non-imaging optics and freeform surface. The result shows that light energy efficiency and illumination uniformity under the freeform surface lens can reach 81% and 77% respectively.

This paper presents an efficient method for rigid registration of 3-D point sets, which intends to match the feature points inspected using touch probe with the points on designed CAD surface. The alignment error is defined as the least square problem, and the sphere radius of the inspection probe is considered. In this framework, the registration problem is converted into acquiring six Euler variables problem by solving nonlinear equations. Thus a matrix transformation of parameter separation is presented to get the approximate resolution. Finally, iterative cycles are provided to calculate the nearest points on designed surface corresponding to the inspection points. Experiment verification is realized for the presented point-set registration method of robot inspection system.

A novel 3D surface modeling method - 3D Surface Modeling based on Spatial Neighbor Points Coupling (SMSNPC) for scattered data points is addressed in this article. The main contribution contains two aspects: First, the 3D model of complex surface can be reconstructed through SMSNPC. Then, model parameters are recognized with Artificial Neural Network (ANN). To demonstrate the efficient applicability of the new algorithm, two groups of point data are presented. One collected by handheld laser scanner is used to validate the reconstruction result, and the other is used to be compared with non-coupling modeling. From the results, the new approach validates the expectation that SMSNPC can match the real complex surface satisfactorily which can't be finished by non-coupling modeling. By comparing the same sample data with non-coupling modeling, it is shown the reconstruction precision of SMSNPC is much higher.

LED is called the fourth generation of lighting, which has already been widely used in display and illumination devices. The junction temperature has directly influence upon the life time and reliability of high-power LED, so keeping the junction temperature of LED is a key issue. A method researching radiators based on finite element analysis was introduced. In this paper, the heat performance of LED COB (chip on board) packaging was studied. The radiating model of LED street lamp with a radiator was introduced, and simulated the changing of parameters of radiator by ANSYS.

An industry robot and external axle scanning system is designed for medium-sized complex workpiece measurement and reverse engineering. An industry robot, which carries a structured light vision sensor to sample data, serves as main data sampling actuator. A workpiece is fixed on an external axle, and any part of it can be scanned on rotated place. The spatial location relationships of the robot, the structured light vision sensor and the external axle must be calibrated before measuring. The real sampled data can be determined via coordinate transformations. The experimental results demonstrate that the system can scan most of parts of the workpiece in one scan so that data merge can be omitted. Compared with traditional scanning methods, the system is more flexible and efficient. Furthermore, the system is more suitable for the manufacturing site.

Based on the analysis on the common methods to handle the Var impact in the system where harmonic exists, a new method is proposed, which can play a profound role in solving Var impact. Through test and practical application, the method deserves promotion in this regard.

Since traditional PI controller cannot realize zero steady-error harmonic compensation for active power filter, In this paper, two types of output current control strategy Composite controller with PI controller and repetitive controller parallel and specified order zero steady-error controller were proposed. Composite controller with PI controller and repetitive controller parallel running improves steady performance since repetitive controller can follow periodic disturbance with zero steady-error, while PI controller ensures rapidly responding. Specified order zero steady-error technology can realize zero steady-error control for single frequency harmonic. Simulation and experiment show these two methods are very useful. However, they should be tested in applications of industry field.

For overcoming some existing problems of traditional Coordinate Measuring Machine (CMM), a novel robot 3D laser measurement system which is representative in reverse engineering is designed in this paper, and its composition and working principle are introduced in detail. For the purpose of measuring the workpiece accurately, the system model must be built, namely, the CCD parameters must be calibrated. To a great extent, system measurement precision is dependent on the precision of system model. Tsai algorithm is known as its moderate computation and high precision, but it is over-dependence on the initial values of parameters. Aiming at this situation, a modified Tsai algorithm for CCD parameters calibration is presented in this paper. In order to validate its effectivity, a case is given, and from the results, it is shown that the modified algorithm has easier computation, faster speed and higher precision than Tsai. Accordingly, the modified algorithm provides a theoretical guarantee for the practicability of 3D laser measurement system.

In this paper, some key technologies of surface inspection are presented. Based on a robot manipulator, a new radius compensation of spherically tipped touch probe is first discussed, and the calibration algorithm for robot hand to eye is proposed. Different from traditional CMM based approach, the point-set registration is derived as a constrained optimization problem, then some issues concerning with the inspection path planning for complex workpiece are described, which is formulated as points distribution, stylus obstacle avoidance and path optimization problems.

This paper presents an efficient method for rigid registration of 3-D point sets, which intends to match the feature points inspected by armed inspection robots with the points on designed CAD surface. The alignment error is defined as the least square problem, and the sphere radius of the inspection probe is considered. In this framework, the matching problem is converted into acquiring six Euler variables problem by solving nonlinear equations. Thus a matrix transformation of parameter separation is presented to get the approximate resolution. The validity and effectivness is tested via real surface matching experiment.

In complicated multi-objective optimization, it often happens that points in part region of Pareto front are easy to get, but in others are difficult. To obtain evenly distributed Pareto optimal solution, we construct dynamical crossover and mutation probability which can self-adaptively adjust the number of individuals engaged in crossover and mutation, combine with the fitness function constructed by weighted min-max strategy in which the weight is uniformly designed, to present a new multi-objective evolutionary algorithm (DMOEA). To evaluate the performance of our algorithm, we compare the numerical results of our algorithm with the MOEA/D-DE and NSGA-II-DE, the comparison shows that our algorithm is very efficient.

This paper investigates cooperative control problems in formation of mobile robots under the nonholonomic constraints. A new method of motion control for formation is presented, which is based on piecewise smooth dynamic framework. It is attractive for its adaptability to the formation structure and desired trajectory. The quality of formation keeping can be evaluated by the instantaneous errors of formation offset and spacing distance. Some kinematics laws are developed to regulate and maintain the formation shape. Simulation results obtained using this approach are then provided.

This paper is concerned with cooperative control problems in formation of mobile robot under the nonholonomic constraints, which means certain geometrical constraints are imposed on multiple mobile robots throughout their travel. For this purpose, a new method of motion control for formations is presented, which is based on the piecewise smooth dynamic formation framework. In addition, the quality of formation control can be weighted by the error matrixes of formation offset distance and spacing distance. Finally, the kinematics rules are developed to regulate and maintain the formation shape while the group as a whole movement system. Simulation results illustrated the application of these ideas and demonstrated the validity of the proposed framework for a group of robots.

This paper introduces a robot simulation, monitoring and control system based on network and lava. This system uses java to establish monitoring GUI and offers communication port module at the same time. Robot software system offers usual movement modules. Thus, the system can complete multi-robot cooperation simulation, experiments and monitoring by intercommunication. The experiment results indicate that the system implements the functions well.

Infrared Search and Track (IRST) system is one of the most typical airborne sensors for remote target measurement, detection and tracking in fighter planes. In recent years the problem of target recognition and tracking has been studied more and more extensively. However, as regards the important difficulties that target recognition and tracking involves, the problems synthesizing target motion analysis and data process have been ignored to a certain extent. In this paper, the infrared model and kinematic model of targets are described. On the basis of the models, a novel and more practical algorithm of data process for bearings-only tracking applications is formed and the major parameters are defined. Finally data simulation is implemented, and the results demonstrate the new algorithm has a better performance in target recognition and tracking.