Excess materials are left inside aircraft wings due to manual operation errors,and the removal of excess materials is very *** increase removal efficiency,a continuum robot(CR)with a removal end-effector and a stereo ...
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Excess materials are left inside aircraft wings due to manual operation errors,and the removal of excess materials is very *** increase removal efficiency,a continuum robot(CR)with a removal end-effector and a stereo camera is used to remove excess *** size and weight characteristics of excess materials in aircraft wings are analyzed.A novel negative pressure end-effector and a two-finger gripper are designed based on the *** negative pressure end-effector aims to remove nuts,small rivets,and small volumes of aluminum shavings.A two-finger gripper is designed to remove large volumes of aluminum shavings.A stereo camera is used to achieve automatic detection and localization of excess *** to poor lighting conditions in the aircraft wing compartment,supplementary lighting devices are used to improve environmental ***,You Only Look Once(YOLO)v5 is used to classify and detect excess objects,and two training data sets of excess objects in two wings are *** to the limited texture features inside the aircraft wings,this paper adopts an image-matching method based on the results of YOLO v5 *** matching method avoids the performance instability problem based on Oriented Fast and Rotated BRIEF feature point *** verification reveals that the detection accuracy of each type of excess exceeds 90%,and the visual localization error is less than 2 mm for four types of excess *** show the two end-effectors can work well for the task of removing excess material from the aircraft wings using a CR.
It is crucial for unmanned systems to determine their motion information accurately, reliably, and in real time. This function is accomplished by the autonomous navigation module of the unmanned systems. By analogy to...
It is crucial for unmanned systems to determine their motion information accurately, reliably, and in real time. This function is accomplished by the autonomous navigation module of the unmanned systems. By analogy to the animals,the autonomous navigation module can be regarded as the“sensory nerve center” of an unmanned system.
High-voltage withstand tests are essential for electric equipment like power transformers,electric cable lines,gas insulated switchgears *** partial discharge(PD)measurement for such equipment under applied high volta...
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High-voltage withstand tests are essential for electric equipment like power transformers,electric cable lines,gas insulated switchgears *** partial discharge(PD)measurement for such equipment under applied high voltage is also required at the same *** Width Modulation(PWM)-based variable frequency power supply(VFPS)finds wide applications in the series resonance high-voltage testing ***,the steep rising and falling voltage edges in the PWM process will produce large amount of partial discharge interference in a wide spectrum range,which will confuse the real partial discharge signal of the device and lead to the wrong estimation of the insulation *** paper proposes a new VFPS based on the highefficiency linear power amplifier without PD *** topology and principle of the VFPS are given and discussed.A prototype rated at 232 V/35 A was designed and constructed to verify the feasibility of the proposed *** experiments were carried out on the prototype.
To improve locomotion and operation integration, this paper presents an integrated leg-arm quadruped robot(ILQR) that has a reconfigurable joint. First, the reconfigurable joint is designed and assembled at the end of...
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To improve locomotion and operation integration, this paper presents an integrated leg-arm quadruped robot(ILQR) that has a reconfigurable joint. First, the reconfigurable joint is designed and assembled at the end of the legarm chain. When the robot performs a task, reconfigurable configuration and mode switching can be achieved using this joint. In contrast from traditional quadruped robots, this robot can stack in a designated area to optimize the occupied volume in a nonworking state. Kinematics modeling and dynamics modeling are established to evaluate the mechanical properties for multiple modes. All working modes of the robot are classified, which can be defined as deployable mode, locomotion mode and operation mode. Based on the stability margin and mechanical modeling, switching analysis and evaluation between each mode is carried out. Finally, the prototype experimental results verify the function realization and switching stability of multimode and provide a design method to integrate and perform multimode for quadruped robots with deployable characteristics.
The increasing adoption of grid-forming converters(GFMCs)stems from their capacity to furnish voltage and frequency support for power ***,GFMCs employing the current reference saturation limiting method often exhibit ...
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The increasing adoption of grid-forming converters(GFMCs)stems from their capacity to furnish voltage and frequency support for power ***,GFMCs employing the current reference saturation limiting method often exhibit instability during various transient disturbances including grid voltage sags,frequency variations,and phase *** address this problem,this paper proposes a virtual power angle synchronous(δv-SYN)control *** fundamental of this method is to achieve synchronization with the grid using the virtual power angleδv instead of the active *** transient stability characteristics of the proposed method are theoretically elucidated using a novel virtual power angle-power angle(δv-δ)*** key benefit of the proposed method is its robustness to various grid strengths and diverse forms of transient disturbances,eliminating the requirement for fault identification or control ***,it can offer grid-forming support to the grid during grid ***-in-the-loop experimental results validate the theoretical analysis and the performance of the proposed method.
This work focuses on the asynchronous controller design for two-dimensional Markov jump cyberphysical systems against denial-of-service attacks. Firstly, due to the openness of the network, it is vulnerable to cyber-a...
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This work focuses on the asynchronous controller design for two-dimensional Markov jump cyberphysical systems against denial-of-service attacks. Firstly, due to the openness of the network, it is vulnerable to cyber-attacks, resulting in the control input signal may not being sent to the designated location. Meanwhile, considering the influence of transmission delays and unavoidable packet dropout, a hidden Markov model can help to deal with the unavoidable asynchronous phenomenon between the plant mode and the controller mode. Then, by introducing the concepts of time instants and global states into two-dimensional systems, an asynchronous control scheme for two-dimensional Markov jump cyber-physical systems is successfully formulated. Subsequently, recurring to the multi-Lyapunov function method and iterative technology,sufficient conditions are achieved to make sure that the dynamic hidden two-dimensional Markov jump cyberphysical systems are asymptotically mean-square stable. To conclude, an application example related to the metal rolling process is provided to illustrate the feasibility and effectiveness of the presented asynchronous control scheme under aperiodic denial-of-service attacks.
In the summer of 2018–2019,rocket-triggered lightning experiments were conducted in Guangzhou,*** were two types of lightning targets:ground and overhead *** comparing the current and the electric field data in the t...
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In the summer of 2018–2019,rocket-triggered lightning experiments were conducted in Guangzhou,*** were two types of lightning targets:ground and overhead *** comparing the current and the electric field data in the two cases,it was found that when the continuous current level(ICC)and current amplitude(IM)of M-components(current pulses generated during the continuous current stage)are large,the time difference between the electric field peak and the current peak(TD)will always be *** rise time(RT)and half peak width(THPW)of M-components with high ICC and IM are low in both the *** threshold upper limit of TD in the case of lightning striking the ground is higher,approxi-mately 2.6 times than that in the case of lightning striking the overhead *** use an optimised guided wave model to simulate the electric field waveforms of *** was found that the shorter RT and THPW of the M-component,the smaller *** changes in wave speed and IM cannot affect the size of TD,and the impact of distance changes is very *** difference in the threshold upper limit of TD may be related to the significant difference in ground impedance in two cases.
As the wind turbine height increases,the probability of multiple upward leaders flashes within the wind farm *** this study,an upward lightning flash containing 21 upward positive leaders(UPLs)initiated from different...
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As the wind turbine height increases,the probability of multiple upward leaders flashes within the wind farm *** this study,an upward lightning flash containing 21 upward positive leaders(UPLs)initiated from different wind turbines in Zhangbei Wind Farm was *** average speed of the UPLs was 1.2×10^(5) m/s,which mostly decreased to zero before reaching the cloud *** four UPLs developed to cloud height,with prolonged periods of bright light on three of them and with a minimum duration of 126 ms.A total of nine return strokes occurred on the other two dissipated leader channels,and the numbers of strokes on the two channels was six and three,*** average interstroke interval for the return strokes was 10.5 *** of these nine return strokes had peak currents smaller than 10 *** high-speed video frames confirmed that competition does exist between the UPLs,and the range of shielding effects increases as the height of the ULs *** effect of fan rotation on the initiation of upward leaders and the shielding effect between the wind turbines and upward leaders are discussed.
By refueling aircraft while they are in flight,aerial refueling is an efficient technique to extend their endurance and *** Aerial Refueling(AAR)is anticipated to be used to complete aerial refueling for unmanned *** ...
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By refueling aircraft while they are in flight,aerial refueling is an efficient technique to extend their endurance and *** Aerial Refueling(AAR)is anticipated to be used to complete aerial refueling for unmanned *** are three aerial refueling methods:the Probe-and-Drogue Refueling(PDR)refueling method,the flying-boom refueling method,and the boom-drogue-adapter refueling *** paper considers the PDR approach,the most challenging of the three,because the flexible hose-drogue assembly has fast dynamics and is susceptible to various kinds of winds,which makes the probe docking with the drogue *** is divided into four phases,namely the rendezvous phase,joining phase,refueling phase,and reform phase,with the refueling phase being the most *** controller design faces the greatest challenge during the docking control of the refueling phase since it calls for a high level of safety,precision,and *** a result,the modeling and control issues encountered during the refueling phase are typical and *** fundamental idea of AAR is presented in the paper first,after which the characteristics and requirements of AAR are *** progress in modeling and control techniques for the AAR’s refueling phase is then systematically ***,potential future work for high safety,precision,and efficiency requirements is examined and suggested.
In this work,we sought to investigate constrained docking control during shipborne SideArm recovery of an Unmanned Aerial Vehicle(UAV)under preassigned safe docking constraints,rough ocean environments,and different i...
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In this work,we sought to investigate constrained docking control during shipborne SideArm recovery of an Unmanned Aerial Vehicle(UAV)under preassigned safe docking constraints,rough ocean environments,and different initial *** aim was to solve the UAV tracking-lag problem that manifests when attempting to dock with a rapidly moving SideArm and to improve the accuracy and rapidity of ***,together with the formulations of the shipborne SideArm system and environmental airflows,the affine nonlinear dynamics of the hook was established to reduce tracking ***,echo state network approximators with good approximation capacity and low computational consumption were designed to accurately approximate the UAV’s unknown nonlinear *** feedforward compensation provided by these approximators,a nonlinear-mapping-based constrained docking control law was developed for shipborne SideArm recovery of *** approach to controlling the docking trajectory and the forward docking speed of the UAV can achieve rapid and exact docking with a moving SideArm,without violating the preassigned safe docking-constraint *** under different docking scenarios were used to validate the effectiveness and advantages of the proposed docking-control algorithm.
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