Underwater image clarifying based on human visual colour constancy using double-opponency

Underwater images are often with biased colours and reduced contrast because of the absorption and scattering effects when light propagates in water.Such images with degradation cannot meet the needs of underwater operations.The main problem in classic underwater image restoration or enhancement methods is that they consume long calcu-lation time,and often,the colour or contrast of the result images is still unsatisfied.Instead of using the complicated physical model of underwater imaging degradation,we propose a new method to deal with underwater images by imitating the colour constancy mechanism of human vision using double-opponency.Firstly,the original image is converted to the LMS space.Then the signals are linearly combined,and Gaussian convolutions are per-formed to imitate the function of receptive fields(RFs).Next,two RFs with different sizes work together to constitute the double-opponency response.Finally,the underwater light is estimated to correct the colours in the image.Further contrast stretching on the luminance is optional.Experiments show that the proposed method can obtain clarified underwater images with higher quality than before,and it spends significantly less time cost compared to other previously published typical methods.

Fabrication of Waterproof Artificial Compound Eyes with Variable Field of View Based on the Bioinspiration from Natural Hierarchical Micro–Nanostructures

Planar and curved microlens arrays(MLAs)are the key components of miniaturized microoptical systems.In order to meet the requirements for advanced and multipurpose applications in microoptical field,a simple manufacturing method is urgently required for fabricating MLAs with unique properties,such as waterproofness and variable field-of-view(FOV)imaging.Such properties are beneficial for the production of advanced artificial compound eyes for the significant applications in complex microcavity environments with high humidity,for instance,miniature medical endoscopy.However,the simple and effective fabrication of advanced artificial compound eyes still presents significant challenges.In this paper,bioinspired by the natural superhydrophobic surface of lotus leaf,we propose a novel method for the fabrication of waterproof artificial compound eyes.Electrohydrodynamic jet printing was used to fabricate hierarchical MLAs and nanolens arrays(NLAs)on polydimethylsiloxane film.The flexible film of MLAs hybridized with NLAs exhibited excellent superhydrophobic property with a water contact angle of 158°.The MLAs film was deformed using a microfluidics chip to create artificial compound eyes with variable FOV,which ranged from 0°to 160°.

Super-resolution imaging of low-contrast periodic nanoparticle arrays by microsphere-assisted microscopy

We use the label-free microsphere-assisted microscopy to image low-contrast hexagonally close-packed polystyrene nanoparticle arrays with diameters of 300 and 250 nm.When a nanoparticle array is directly placed on a glass slide,it cannot be distinguished.If a 30-nm-thick Ag film is deposited on the surface of a nanoparticle array,the nanoparticle array with nanoparticle diameters of 300 and 250 nm can be distinguished.In addition,the Talbot effect of the 300-nm-diameter nanoparticle array is also observed.If a nanoparticle sample is assembled on a glass slide deposited with a 30-nm-thick Ag film,an array of 300-nm-diameter nanoparticles can be discerned.We propose that in microsphere-assisted microscopy imaging,the resolution can be improved by the excitation of surface plasmon polaritons(SPPs) on the sample surface or at the sample/substrate interface,and a higher near-field intensity due to the excited SPPs would benefit the resolution improvement.Our study of label-free super-resolution imaging of low-contrast objects will promote the applications of microsphere-assisted microscopy in life sciences.

Ultra-low temperature anodic bonding of silicon and glass based on nano-gap dielectric barrier discharge

The article improves the process of dielectric barrier discharge(DBD)activated anode bonding.The treated surface was characterized by the hydrophilic surface test.The results showed that the hydrophilic angle was significantly reduced under nano-gap conditions and the optimal discharge voltage was 2 kV.Then,the anodic bonding and dielectric barrier discharge activated bonding were performed in comparison experiments,and the bonding strength was characterized by tensile failure test.The results showed that the bonding strength was higher under the nano-gap dielectric barrier discharge.This process completed 110°C ultra-low temperature anodic bonding and the bonding strength reached 2 MPa.Finally,the mechanism of promoting bonding after activation is also discussed.

Trajectory planning for biped robot walking on uneven terrain - Taking stepping as an example

According to the features of movements of humanoid robot, a control system for humanoid robot walking on uneven terrain is present. Constraints of stepping over stairs are analyzed and the trajectories of feet are calculated by intelligent computing methods. To overcome the shortcomings resulted from directly controlling the robot by neural network （NN） and fuzzy logic controller （FLC）, a revised particle swarm optimization （PSO） algorithm is proposed to train the weights of NN and rules of FLC. Simulations and experiments on different control methods are achieved for a detailed comparison. The results show that using the proposed methods can obtain better control effect.

New Distributed Positioning Algorithm Based on Centroid of Circular Belt for Wireless Sensor Networks

This paper presents a new distributed positioning algorithm for unknown nodes in a wireless sensor network. The algorithm is based exclusively on connectivity. First, assuming that the positions of the anchor nodes are already known, a circular belt containing an unknown node is obtained using information about the anchor nodes that are in radio range of the unknown node, based on the geometric relationships and communication constraints among the unknown node and the anchor nodes. Then, the centroid of the circular belt is taken to be the estimated position of the unknown node. Since the algorithm is very simple and since the only communication needed is between the anchor nodes and the unknown node, the communication and computational loads are very small. Furthermore, the algorithm is robust because neither the failure of old unknown nodes nor the addition of new unknown nodes influences the positioning of unknown nodes to be located. A theoretical analysis and simulation results show that the algorithm does not produce any cumulative error and is insensitive to range error, and that a change in the number of sensor nodes does not affect the communication or computational load. These features make this algorithm suitable for all sizes of low-power wireless sensor networks.

SHUYU Robot:An Automatic Rapid Temperature Screening System

The health of people around the world and the global economy are under substantial threat from the outbreak of pandemics[1].Controlling pandemics is extremely challenging,with preventing the spread of pathogens the most important and critical step.Of all preventative actions,body temperature screening is undoubtedly highly necessary and effective[2].

Ⅳ期结肠直肠癌进行姑息性腹腔镜切除术

PURPOSE: Issues surrounding the safety and efficacy of palliative laparoscopic resections for patients with Stage IV colorectal cancer have not been explicitly examined in the literature. This article describes our experience with laparoscopic procedures for patients with Stage IV colorectal cancer and compares thir perioperative outcomes to a contemporaneous group of patients with clinically curable (Stages I- III) disease. METHODS: A prospective database of laparoscopic resections for colorectal cancer performed between 1991 and 2002 was reviewed. Data regarding patient demographics, perioperative morbidity and mortality, operative times, conversion rates, and length of stay were extracted. Statistical analysis included chi-squared and Student s t-tests as required and P ≤ 0.05 was considered significant. RESULTS: A total of 375 cases were identified, of these 49 (13 percent) underwent laparoscopic palliative resections while 326 (87 percent) patients had resections for cure. When comparing palliative to curative procedures, there were no differences in intraoperative (4 percent vs. 9 percent) or postoperative complications (14 percent vs. 12 percent), perioperative mortality (8 percent vs. 4 percent), or length of hospital stay. Patients with Stage IV disease had larger tumors (5.4 ± 2.3 cm vs. 4.6 ± 2.6 cm, P = 0.04) which contributed to an increased rate of conversion (22 percent vs. 11 percent, P = 0.05) with most conversions secondary to tumor fixation or bulk (64 percent) preventing determination of resectability. CONCLUSIONS: A palliative laparoscopic resection is a safe and feasible option and presents acceptable morbidity and mortality in patients with Stage IV colorectal cancer. Importantly, in this difficult group of patients, our results compare favorably with those from previously published series of open procedu res.

A decision aid for the port placement problem in robot-assisted hysterectomy

Objective:In robot-assisted minimally invasive surgery,proper port positioning ensures that surgical tools have adequate access to the surgical site and avoids mid-surgery collisions of robotic arms.To date,several guidelines have been proposed for more accurate port placement.However,challenges remain due to variations in patient morphology,anatomy,and,in particular,organ displacement due to insuf-flation in certain laparoscopic procedures.The objective of this study was to design and develop a de-cision aid for optimal port placement in robot-assisted hysterectomy that accounts for patient variability and organ displacement due to insufflation.Methods:Three components were constructed:a robot model,a patient-specific model,and an opti-mization algorithm.The three components were integrated,and the system was verified using four different patients who underwent robotic hysterectomy.Once verified,two expert surgeons were asked to evaluate the decision aid for face and construct validity.A usability test was conducted using a torso phantom with target organs located in three different locations.Two expert surgeons performed a simulated hysterectomy task with and without the decision aid to evaluate performance and satisfaction.Results:The optimization algorithm was sensitive to individual differences in anatomy in the four pa-tients.Expert surgeons successfully established face and construct validity.Usability test results showed a 28%-40% reduction in time to task completion with the optimized ports compared to expert-determined port locations without using the decision aid.Conclusions:The decision aid,based on an individualized patient-specific model,robot model,and optimization algorithm,was shown to be effective at addressing the challenges of displaced organs due to insufflation in robot-assisted hysterectomy.The face and construct validity of the decision aid was established by expert surgeons,while efficiency gains in task performance were demonstrated experimentally.

Process planning and contour-based error compensation for precision grinding of miniature scalpels

Miniature scalpels are mainly used in microsurgeries such as ophthalmic and cardiovascular surgeries.The size of a miniature scalpel is only a few millimeters,and the precision of the blade shape is high,which makes production of miniature scalpels extremely difficult.This study proposes a new sharpening process for grinding miniature scalpels on a four-axis machine tool.A post-processing algorithm for a four-axis grinding machine based on a kinematics model is established.We then propose a corresponding parameter calibration method for the parameters used in the kinematics model.Because of possible errors in the parameter calibration,a contour-based error compensation method is proposed for accurate adjustments to the edge shape following grinding.This can solve the problem of large deviations between the actual edge shape after grinding and the ideal edge shape.The effectiveness of the proposed process planning and error compensation method is verified experimentally,and the grinding process parameters of the miniature scalpel are optimized to improve its surface processing quality.The sharpness of the optimized miniature scalpel is less than 0.75 N,and the blade shape is symmetrical,which meets the technical requirements of miniature scalpels.

基于AFM的纳米线沉积加工方法

纳米器件具有巨大的应用潜力,但是纳米器件中各部件的连接问题是困扰纳米器件加工的一个难题.本文介绍了一种基于AFM的纳米线条沉积加工方法,该方法有望用作纳米器件的焊接手段,改善纳米部件的物理固定和电气连接.采用本文的方法,可以加工连续的纳米线条,而不是通过沉积一排点连通成线.该方法包括两个特点,其一是采用电流诱导沉积发生,而不是电压,实验表明施加电流比施加电压得到的纳米线更加平滑连续;其二,AFM沉积加工是基于场蒸发的原理,因此针尖基底距离是影响场蒸发的重要因素,本文采用了一种简便易行的针尖基底距离控制方法,使沉积加工操作简单易行.

欠驱动三连杆机器人的混杂控制方法

针对第二关节为被动关节的欠驱动三连杆机器人,提出一种混杂控制方法.欠驱动三连杆机器人的运动空间分为3个阶段:退化阶段、摇起阶段和平衡阶段.首先,在退化阶段,对第三关节构造Lyapunov函数,并针对此函数设计控制律使其连杆相对于前一连杆自然伸展,使系统退化为类Pendubot机器人;同时基于能量不断增加的思想设计第一关节控制律,以节省后阶段的能量控制时间.其次,在摇起阶段,保持第三关节控制律形式不变;通过仅控制系统能量和同时控制系统能量、角速度两种方法设计第一关节控制律,使系统进入平衡区.最后,对退化后的系统采用线性控制将其稳定在竖直向上不稳定平衡点上.数值仿真结果表明文中所提方法具有控制时间短,所需力矩小等优点.

Multi-AUV SOM task allocation algorithm considering initial orientation and ocean current environment

There is an ocean current in the actual underwater working environment. An improved self-organizing neural network task allocation model of multiple autonomous underwater vehicles(AUVs) is proposed for a three-dimensional underwater workspace in the ocean current. Each AUV in the model will be competed, and the shortest path under an ocean current and different azimuths will be selected for task assignment and path planning while guaranteeing the least total consumption. First, the initial position and orientation of each AUV are determined. The velocity and azimuths of the constant ocean current are determined. Then the AUV task assignment problem in the constant ocean current environment is considered. The AUV that has the shortest path is selected for task assignment and path planning. Finally, to prove the effectiveness of the proposed method, simulation results are given.

Resonant frequencies of a piezoelectric drum transducer

This paper presents a piezoelectric-metal structure called a drum transducer. An equation for calculating the resonance frequency of the drum transducer is obtained based on thin plate elastic theory of piezoelectric and metal material combined with the Rayleigh-Ritz method. The finite element method (FEM) was used to predict the excitation frequency of the drum transducer. To verify the theoretical analysis, the input impedance characteristic of the drum transducer was measured using an experimental method. The results obtained from theoretical analysis were in very good agreement with those from the FEM and experimental results. The effect of geometrical changes to the thick-walled steel ring of the drum transducer at the first resonance frequency is also described. The calculated results were found to be in good agreement with the FEM results. The results indicate that the first resonance frequency of the drum decreases with the increasing inner diameter of the thick-walled steel ring.

Robot impedance control and passivity analysis with inner torque and velocity feedback loops

Impedance control is a well-established technique to control interaction forces in robotics. However, real implementations of impedance control with an inner loop may suffer from several limitations. In particular, the viable range of stable stiffness and damping values can be strongly affected by the bandwidth of the inner control loops （e.g., a torque loop） as well as by the filtering and sampling frequency. This paper provides an extensive analysis on how these aspects influence the stability region of impedance parameters as well as the passivity of the system. This will be supported by both simulations and experimental data. Moreover, a methodology for designing joint impedance controllers based on an inner torque loop and a positive velocity feedback loop will be presented. The goal of the velocity feedback is to increase （given the constraints to preserve stability） the bandwidth of the torque loop without the need of a complex controller.

Velocity Control of a Bounding Quadruped via Energy Control and Vestibular Reflexes

In this paper a bio-inspired approach of velocity control for a quadruped robot running with a bounding gait on compliant legs is set up. The dynamic properties ofa sagittal plane model of the robot are investigated. By analyzing the stable fixed points based on Poincare map, we find that the energy change of the system is the main source for forward velocity adjustment. Based on the analysis of the dynamics model of the robot, a new simple linear running controller is proposed using the energy control idea, which requires minimal task level feedback and only controls both the leg torque and ending impact angle. On the other hand, the functions of mammalian vestibular reflexes are discussed, and a reflex map between forward velocity and the pitch movement is built through statistical regression analysis. Finally, a velocity controller based on energy control and vestibular reflexes is built, which has the same structure as the mammalian nervous mechanism for body posture control. The new con- troller allows the robot to run autonomously without any other auxiliary equipment and exhibits good speed adjustment capa- bility. A series simulations and experiments were set to show the good movement agility, and the feasibility and validity of the robot system.

An epidermal sEMG tattoo-like patch as a new human–machine interface for patients with loss of voice

Throat cancer treatment involves surgical removal of the tumor,leaving patients with facial disfigurement as well as temporary or permanent loss of voice.Surface electromyography(sEMG)generated from the jaw contains lots of voice information.However,it is difficult to record because of not only the weakness of the signals but also the steep skin curvature.This paper demonstrates the design of an imperceptible,flexible epidermal sEMG tattoo-like patch with the thickness of less than 10μm and peeling strength of larger than 1N cm−1 that exhibits large adhesiveness to complex biological surfaces and is thus capable of sEMG recording for silent speech recognition.When a tester speaks silently,the patch shows excellent performance in recording the sEMG signals from three muscle channels and recognizing those frequently used instructions with high accuracy by using the wavelet decomposition and pattern recognization.The average accuracy of action instructions can reach up to 89.04%,and the average accuracy of emotion instructions is as high as 92.33%.To demonstrate the functionality of tattoo-like patches as a new human–machine interface(HMI)for patients with loss of voice,the intelligent silent speech recognition,voice synthesis,and virtual interaction have been implemented,which are of great importance in helping these patients communicate with people and make life more enjoyable.

Wearable multichannel pulse condition monitoring system based on flexible pressure sensor arrays

Pulse diagnosis is an irreplaceable part of traditional Chinese medical science.However,application of the traditional pulse monitoring method was restricted in the modernization of Chinese medical science since it was difficult to capture real signals and integrate obscure feelings with a modern data platform.Herein,a novel multichannel pulse monitoring platform based on traditional Chinese medical science pulse theory and wearable electronics was proposed.The pulse sensing platform simultaneously detected pulse conditions at three pulse positions(Chi,Cun,and Guan).These signals were fitted to smooth surfaces to enable 3-dimensional pulse mapping,which vividly revealed the shape of the pulse length and width and compensated for the shortcomings of traditional single-point pulse sensors.Moreover,the pulse sensing system could measure the pulse signals from different individuals with different conditions and distinguish the differences in pulse signals.In addition,this system could provide full information on the temporal and spatial dimensions of a person’s pulse waveform,which is similar to the true feelings of doctors’fingertips.This innovative,cost-effective,easily designed pulse monitoring platform based on flexible pressure sensor arrays may provide novel applications in modernization of Chinese medical science or intelligent health care.

Design,Modeling and Experimentation of a Biomimetic Wall-climbing Robot for Multiple Surfaces

Wall-climbing robots can work on steep terrain and obtain environment information in three dimensions for human in real time,which can improve operation efficiency.However,traditional single-mode robots cannot ensure the stable attachment on complex wall surfaces.Inspired by the structure characteristics of flies and clingfishes,three bionic structures including the flexible spine wheel,the adhesive material and the adsorption system are proposed.Aiming at task requirements on multiple walls and based on the above three bionic structures,a wall-climbing robot with the composed mode of“grabbing+adhesion+adsorption”is presented v/a the law of mechanism configuration synthesis.Using static analysis,the safe attachment conditions for the robot on smooth and rough walls are that the adsorption force is 30 N or more.Based on Newton's Euler and Lagrange formulas,the dynamic equations of the robot on vertical walls are established to deduce that the maximum theoretical torque of the driving motor is 1.43 N·m at a uniform speed.Finally,the prototype of the wall-climbing robot is manufactured and tested on the vertical lime wall,coarse sandpaper wall and acrylic ceiling wall.Meanwhile,experiment results imply that the average maximum moving speed and the corresponding load are 7.19 cm·s-1 and 0.8 kg on the vertical lime wall,7.78 cm·s-1 and 0.6 kg on the coarse sandpaper wall,and 5.93 cm·s-1 and 0.2 kg on the acrylic ceiling wall respectively.These findings could provide practical reference for the robot’s application on walls.