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Medical image segmentation and registration are two tasks to analyze the anatomical structures in clinical research. Still, deep-learning solutions utilizing the connections between segmentation and registration remain underdiscovered. This article designs a joint learning framework named RSegNet that can realize concurrent deformable registration and segmentation by minimizing an integrated loss function, including three parts: diffeomorphic registration loss, segmentation similarity loss, and dual-consistency supervision loss. The probabilistic diffeomorphic registration branch could benefit from the auxiliary segmentations available from the segmentation branch to achieve anatomical consistency and better deformation regularity by dual-consistency supervision. Simultaneously, the segmentation performance could also be improved by data augmentation based on the registration with well-behaved diffeomorphic guarantees. Experiments on the human brain 3-D magnetic resonance images have been implemented to demonstrate the effectiveness of our approach. We trained and validated RSegNet with 1000 images and tested its performances on four public datasets, which shows that our method successfully yields concurrent improvements of both segmentation and registration compared with separately trained networks. Specifically, our method can increase the accuracy of segmentation and registration by 7.0% and 1.4%, respectively, in terms of Dice scores. Note to Practitioners—Registration and segmentation of medical images are two significant tasks in medical research and clinical application. However, most existing approaches consider these two tasks independently while neglecting the potential association between them. Therefore, we suggest a new approach that combines these two tasks into one joint deep learning framework, boosting registration, and segmentation performance by introducing dual-consistency supervision. Besides, our framework could generate outputs within 1 s by taking an affinely aligned medical image pair as input, which is suitable for time-critical requirements in a clinic. We tested it on four public datasets and achieved state-of-the-art performance to demonstrate the proposed method’s feasibility and robustness. Furthermore, our proposed RSegNet is a general learning framework suitable for various image modalities and anatomical structures. Hence, we expect our framework to serve as a practical clinical tool to speed up medical image analysis procedures and improve diagnostic accuracy. [ABSTRACT FROM AUTHOR]

Medical image segmentation and registration have vital roles in computer-assisted diagnosis procedures, challenging tasks suffering from various limitations and artifacts inside images. Recently, deep learning techniques accomplish these two tasks and achieve outstanding performances. However, most deep learning-based methods overlook the potential correlation between each other. In this paper, an unsupervised probabilistic model named U-RSNet is proposed to realize concurrent medical image registration and segmentation in one framework. Specifically, the unsupervised segmentation branch is derived from Bayesian inference. The prior warped atlas for segmentation can be obtained by deforming a known probabilistic atlas by the corresponding invertible deformation field with a well-behaved diffeomorphic guarantee, which can perfectly integrate these two tasks to form a complete intelligent prediction system. In this case, the segmentation performance could be largely improved based on the warped probabilistic atlas obtained from the registration branch. Experiments on human brain 3D magnetic resonance images have demonstrated the effectiveness of our approach. We trained and validated U-RSNet with 1000 images and tested its performances on four public datasets. We showed our method successfully realized concurrent segmentation and registration and yielded better segmentation results than a separately trained network. [ABSTRACT FROM AUTHOR]

Reconfigurable structures can perform multiple functions and are useful in confined environments with complicated access. To extend the complexity of configurations achievable with reconfigurable mechanisms, remotely reconfigurable mechanisms are explored. Magnetically responsive phase change materials are selected for actuation, and origami backbones as the structure. Modulating the mechanism's coupling and constraints, multiple configurations are achieved. Three functional aspects of in situ reconfiguration are demonstrated. First, selective attachment and actuation enable remote mechanisms to deploy and actuate. Second, reconfiguration that modifies the constraints allows for new kinematics even in confined environments. Third, the actuator can construct and change the configuration of an origami structure, allowing subsequent functions to emerge. Tetherless interface reconfiguration is demonstrated with an in situ needle puncture and escape room puzzle, which can benefit existing robotic applications in confined spaces. [ABSTRACT FROM AUTHOR]

In a paired-point rigid registration, target registration error (TRE) is deemed to be the most important quality metric. TRE usually cannot be directly measured, and thus many TRE estimation algorithms have been proposed. However, target localization errors (TLEs) in two spaces are not considered in the definition of TRE. In this paper, we propose a new type of evaluation metric that is referred to as total TRE (TTRE) at a given target point with TLE incorporated. Statistics including mean, root mean square (rms), and covariance matrix of TTRE are derived without making any assumption of the TLE magnitude. TTRE and fiducial registration error (FRE) are proved to be uncorrelated when an ideal weighting scheme is adopted in solving the registration problem. The proposed error model is validated through extensive experiments. In the first experiment with random fiducials and targets, in 90% of the test cases, there shows no difference between the predicted and simulated TTRE statistics when six fiducials are used. In the second experiment of deep-brain stimulation surgery, the mean value of CC(TTRE,FRE) being $8.9246\times 10^{-4}\pm 0.0389 $ was observed, which indicates that TTRE and FRE are uncorrelated. In the third experiment of surgical tool-tip tracking, the mean and standard deviation of percentage differences between predicted and simulated TTRE rms values are $2.22\%\pm 0.77\%$ for the planar tool and $2.62\%\pm 0.59\%$ for the textral tool. In summary, our proposed algorithm can well model the TTRE metric. Note to Practitioners—This paper was motivated by considering the existence of target localization error in two spaces to be registered in a rigid point-based registration. Given fiducial localization error (FLE) and TLE probability distributions, the proposed TTRE model gives the covariance matrix and root mean square of TTRE at a given target point. The possible applications of the proposed TTRE model in an image-guided surgery (IGS) include: 1) estimation of surgical tool-tip tracking error distribution when pivot calibration uncertainty is considered; 2) accuracy evaluation of an image-to-patient registration; 3) updating of a preoperative surgical plan on a computed tomography/MRI image to consider the registration error at a given target point; and 4) estimation of real-time tool-tip error in touching a desired “true” surgical target, such as a tumor during surgery. To use the proposed error estimation algorithm, FLE and TLE in two spaces to be registered have to be known or estimated in advance to a registration process. The proposed error model is validated through extensive simulations. [ABSTRACT FROM AUTHOR]

Endowing robots with reversible phase transition ability, especially between elastomer and fluid states, can significantly broaden their functionality and applicability. Limited attempts have been made to realize the reversible elastomer–fluid transition. Existing phase transition materials in robotics have over‐hard (≈4 GPa) or over‐soft (≈4 kPa) stiffness in the solid states, which should be further investigated to perform more compliant motions. To address these challenges, a reversible elastomer–fluid transition mechanism enabled by magnetically induced hot melt materials (MIMMs) is presented. The transition principle is explained and material characterizations are conducted. MIMMs‐based metamorphosic robots endow self‐metamorphosing abilities, such as self‐healing, spatial reshaping, self‐division/assembly, and additive manufacturability. When interacting with external environments, MIMMs‐based robots can perform further multifunctional abilities, such as collaborations for structure repairs, swimming by symbiosis with external objects, flowing through a narrow terrain by transiting to fluid, and working with elastomeric structures for stiffness‐variable fluid soft actuators. The proposed elastomer–fluid transitions open a new path for robots to generate more flexible and metamorphosic motions, thereby addressing the cross‐phase transformation challenges that soft robots face. [ABSTRACT FROM AUTHOR]

Under the effects of alternating current (AC), the resistance and reactance of electric machine windings are different from their static state. As electric machine windings usually comprise many conductors, it makes the modeling and analysis very cumbersome using the finite element method. This paper presents an analytical method for computing AC resistance and reactance of electric machine windings placed in ferromagnetic slots, which is more convenient and efficient, and could be extended to the slots with different complex structures. First, the slot is divided into a number of layers based on the concept of discretization. Then, the magnetic field governing equation is established, and the distributions of magnetic field intensity and the current density of conductors under AC conditions are solved. By Poynting's theorem, the complex power flowing into the conductors is calculated, and then the effective resistance and reactance of the windings are obtained. Finally, the deduced analytical solutions are compared with the finite element method, and the results show that they have a good agreement for both single-layer winding and the double-layer windings with current phase difference. The presented analytical model is useful for understanding the AC effects and optimization of electric machine windings placed in ferromagnetic slots. [ABSTRACT FROM AUTHOR]

Magnetic resonance imaging (MRI) is beneficial for imaging-guided procedures because it provides higher resolution images and better soft tissue contrast than computed tomography (CT), ultrasound, and X-ray. MRI can be used to streamline diagnostics and treatment because it does not require patients to be repositioned between scans of different areas of the body. It is even possible to use MRI to visualize, power, and control medical devices inside the human body to access remote locations and perform minimally invasive procedures. Therefore, MR conditional medical devices have the potential to improve a wide variety of medical procedures; this potential is explored in terms of practical considerations pertaining to clinical applications and the MRI environment. Recent advancements in this field are introduced with a review of clinically relevant research in the areas of interventional tools, endovascular microbots, and closed-loop controlled MRI robots. Challenges related to technology and clinical feasibility are discussed, including MRI based propulsion and control, navigation of medical devices through the human body, clinical adoptability, and regulatory issues. The development of MRI-powered medical devices is an emerging field, but the potential clinical impact of these devices is promising. [ABSTRACT FROM AUTHOR]

We investigate a new framework of surgical instrument detection based on power-varying ultrasound images with simple and efficient pixel-wise intensity processing. Without using complicated feature extraction methods, we identified the instrument with an estimated optimal power level and by comparing pixel values of varying transducer power level images. The proposed framework exploits the physics of ultrasound imaging system by varying the transducer power level to effectively distinguish metallic surgical instruments from tissue. This power-varying image-guidance is motivated from our observations that ultrasound imaging at different power levels exhibit different contrast enhancement capabilities between tissue and instruments in ultrasound-guided robotic beating-heart surgery. Using lower transducer power levels (ranging from 40 to 75% of the rated lowest ultrasound power levels of the two tested ultrasound scanners) can effectively suppress the strong imaging artifacts from metallic instruments and thus, can be utilized together with the images from normal transducer power levels to enhance the separability between instrument and tissue, improving intraoperative instrument tracking accuracy from the acquired noisy ultrasound volumetric images. We performed experiments in phantoms and ex vivo hearts in water tank environments. The proposed multi-level power-varying ultrasound imaging approach can identify robotic instruments of high acoustic impedance from low-signal-to-noise-ratio ultrasound images by power adjustments. [ABSTRACT FROM AUTHOR]

This paper has proposed a novel fiber Bragg grating (FBG)-based hybrid displacement and force sensor with a compact structure and excellent resolution by using the transverse property of a tightly suspended and slightly bent optical fiber. The optical fiber, embedded with an FBG element, has been suspended with its ends fixed on the sensor frame and implemented with a pre-tension force by the displacement loading along its vertical direction to form a bent shape. A conversion mechanism has been designed to convert the displacement and force inputs into the transverse movement of different points along the suspended fiber. Experimental results show that the displacement sensitivity and force sensitivity are −219.69 pm/mm within the range of 0–2.5 mm and −345.2 pm/N with a high calculated resolution of 2.9 mN, respectively. Results from both the displacement and force experiments have illustrated a close agreement with values from commercial sensors. [ABSTRACT FROM AUTHOR]

Due to the robustness against the uncertainties, conventional sliding mode control (SMC) has been extensively developed for fault-tolerant control (FTC) system. However, the FTCs based on conventional SMC provide several disadvantages such as large transient state error, less robustness, and large chattering, that limit its application for real application. In order to enhance the performance, a novel adaptive third-order SMC, which combines a novel third-order sliding mode surface, a continuous strategy and an adaptation law, is proposed. Compared with other innovation approaches, the proposed controller has an excellent capability to tackle several types of actuator faults with an enhancing on robustness, precision, chattering reduction, and time of convergence. The proposed method is then applied for an attitude control of a spacecraft and the results demonstrate the superior performance. [ABSTRACT FROM PUBLISHER]

When a robot is required to perform specific tasks defined in the world frame, there is a need for finding the coordinate transformation between the kinematic base frame of the robot and the world frame. The kinematic base frame used by the robot controller to define and evaluate the kinematics may deviate from the mechanical base frame constructed based on structural features. Besides, by using kinematic modeling rules such as the product of exponentials (POE) formula, the base frame can be arbitrarily located, and does not have to be related to any feature of the mechanical structure. As a result, the kinematic base frame cannot be measured directly. This paper proposes to find the kinematic base frame by solving a hand-eye calibration problem using 3D position measurements only, which avoids the inconvenience and inaccuracy of measuring orientations and thus significantly facilitates practical operations. A closed-form solution and an iterative solution are explicitly formulated and proved effective by simulations. Comprehensive analyses of the impact of key parameters to the accuracy of the solution are also carried out, providing four guidelines to better conduct practical operations. Finally, experiments on a 7-DOF industrial robot are performed with an optical tracking system to demonstrate the superiority of the proposed method using position data only over the method using full pose data. [ABSTRACT FROM AUTHOR]

Wheeled mobile robots (WMRs) are often used for maintenance of round pipes or ducts, which can typically be represented as a cylindrical workspace. Working in round pipes or ducts, kinematic models of WMRs are different from those applying on a plane and thus pose significant challenges in terms of kinematic analysis and motion control. To address these challenges, the kinematic properties of WMRs in a cylindrical workspace are analyzed in this paper. First, we discuss the kinematic properties of a single wheel in a cylindrical workspace. Then, we analyze the geometric constraints of WMRs in round pipes or ducts with analytical geometry. Based on these analyses, kinematic properties of WMRs in cylindrical workspaces are discussed with screw theory. A control law based on biaxial clinometer information is proposed, and it enables the robot to move horizontally in round pipes or ducts. Finally, the motion of a single wheel purely rolling in a cylindrical workspace is simulated. Experiments using a car-like mobile robot moving in round ducts are carried out to show the feasibility of the proposed algorithm. [ABSTRACT FROM AUTHOR]

A broadband photonic crystal (PhC) waveguide crossing is proposed with low crosstalk. On the basis of the structure, two 1 × 2 PhC λ-routers are constructed by exploiting several PhC point-defect micro-cavities. By means of the interference coupling between the point-defect modes in micro-cavities, the incidence light with the resonant wavelength can be routed to the designed output port in the router. To achieve the high routing efficiency with narrow pass-band width, the micro-cavity structure is elaborately engineered to satisfy the condition of the quality factor ratio, which consists of these rods with the gradual radii. Their performances are demonstrated by the numerical results calculated by the finite difference time domain (FDTD) and the plane wave expansion (PWE) methods. Furthermore, the analysis of the 4 × 4 λ -router configuration, obtained by assembling these basic wavelength routing elements, is reported to highlight its performances with a theoretical maximum crosstalk between the ports equal to −27.23 dB. [ABSTRACT FROM AUTHOR]

Snake-like flexible manipulators are widely used in minimally invasive surgery (MIS), which require adequate dexterity in confined workspace. Typically, the design mechanisms of these manipulators include tendon-driven mechanism and concentric tube mechanism. Though, the workspace and dexterity of these designs are limited due to the lack of control in either the length of the bending section or the curvature of the bending section at the distal end. In this paper, we present a novel constrained wire-driven flexible mechanism (CWFM), in which both the length and the curvature of the bending section are controllable. The idea is to employ an active constraint to control the length of the bending section and use the wires to control the curvature of the bending section. Compared to the existing designs based on wire-driven flexible mechanism (WFM), CWFM has expanded workspace and enhanced dexterity while its size is not sacrificed. Additional benefits include much reduced sweeping area and controllable stiffness. Based on the computer simulation, on average, CWFM with the same size as WFM can improve the dexterity by 4.69 times and reduce the sweeping area to 20.5%. [ABSTRACT FROM AUTHOR]

Due to their wide range of clinical application possibilities, magnetic actuation technologies have grabbed the attention of researchers worldwide. The design, execution, and analysis of magnetic catheter systems have advanced significantly during the last decade. The review focuses on magnetic actuation for catheter steering and control of the device, which will be explored in detail in the following sections. There is a discussion of future work and the challenges of the review systems, and the conclusions are finally addressed. [ABSTRACT FROM AUTHOR]

We introduce and investigate the feasibility of a novel iterative blind phase noise inter-carrier interference (ICI) mitigation scheme for coherent optical orthogonal frequency division multiplexing (CO-OFDM) systems. The ICI mitigation scheme is performed through the combination of frequency-domain symbol decision-aided estimation and the ICI phase noise time-average approximation. An additional initial decision process with suitable threshold is introduced in order to suppress the decision error symbols. Our proposed ICI mitigation scheme is proved to be effective in removing the ICI for a simulated CO-OFDM with 16-QAM modulation format. With the slightly high computational complexity, it outperforms the time-domain average blind ICI (Avg-BL-ICI) algorithm at a relatively wide laser line-width and high OSNR. [ABSTRACT FROM AUTHOR]

This paper presents a three dimensional ultrasound (3DUS)-based visual servoing technique for intraoperative tracking of the motion of both surgical instruments and tissue targets. In the proposed approach, visual servoing techniques are used to control the position of a virtual ultrasound probe so as to keep a target centered within the virtual probe's field-of-view. Multiple virtual probes can be servoed in parallel to provide simultaneous tracking of instruments and tissue. The technique is developed in the context of robotic beating-heart intracardiac surgery in which the goal of tracking is to both provide guidance to the operator as well as to provide the means to automate the surgical procedure. To deal with the low signal-to-noise ratio (SNR) of the 3DUS volumes, an intensity-based method is proposed that requires no primitive extraction or image segmentation since it directly utilizes the image intensity information as a visual feature. This approach is computationally efficient and can be applied to a wide range of tissue types and medical instruments. This paper presents the first validation of these techniques through offline robot and tissue tracking using actual in vivo cardiac volume sequences from a robotic beating-heart surgery. [ABSTRACT FROM PUBLISHER]

This paper presents a passive-marker-based optical tracking system utilizing dual Kinect sensors and additional custom optical tracking components. To obtain sub-millimeter tracking accuracy, we introduce robust calibration of dual infrared sensors and point correspondence establishment in a stereo configuration. The 3D localization is subsequently accomplished using multiple back projection lines. The proposed system extends existing inexpensive consumer electronic devices, implements tracking algorithms, and shows the feasibility of applying the proposed low-cost system to surgical training for computer assisted surgeries. [ABSTRACT FROM AUTHOR]

Percutaneous radiofrequency ablation (RFA) is a minimally invasive technique increasingly employed in the treatment of unresectable bone tumours due to its safety, less invasiveness, reduced complications, effectiveness, and predictability. This paper investigates a new pipeline of computer-assisted interventional system with navigation and planning functions for percutaneous RFA as an useful tool to improve clinicians’ performance. Unlike traditional open procedures, percutaneous RFA requires image guidance because a direct visual field of surgical targets is unavailable. Radiographic imaging can be used intra-operatively for navigation, but it generates radiation exposure to patients and clinicians. To reduce the risk of radiation exposure and enhance the performance in computer-assisted bone tumor RFA, this paper addressed two key problems: (1) statistical atlas is employed to construct a global navigation map by deformable registration using a minimal number of intra-operative fluoroscopic images to localize the tumor and (2) a multiple-objective optimization for treatment planning of large tumor RFA is proposed to obtain optimal trajectories and ablation coverage by considering clinical constraints. The proposed system was validated by experiments, showing that the construction error of patient-specific model was 0.84 mm in terms of surface-to-surface distance measure and the optimal planning achieved 100% tumor coverage under multiple clinical constraints. [ABSTRACT FROM AUTHOR]

Abstract: We present a photonic crystal (PC) three-port channel drop filter (CDF) with flat-top response and high quality factor value of 8836.7, and it can be used in the dense wavelength division multiplexing (DWDM) system. The CDF is engineered based on the three-port system with the wavelength-selective reflection feedback, where both micro-cavities are the synthesized coupled-resonators. In this case, the conditions to achieve complete power transfer are same to that of the corresponding three-port system while both micro-cavities are the single-mode resonators. As two micro-cavities are single point-defect resonators or synthesized coupled-resonators respectively, it is confirmed that these CDFs exhibit different response characteristics by the simulation results calculated by using two dimensional finite-difference time-domain (2D-FDTD) method, and these filters will find applications in future wavelength division multiplexing (WDM) optical communication systems. [Copyright &y& Elsevier]

Natural orifice translumenal endoscopic surgery (NOTES) is the latest surgery paradigm in which the abdominal cavity is accessed via the body's natural orifice, e.g., vagina, mouth, etc. Compared with traditional laparoscopic surgery, NOTES completely eliminates the skin incision and therefore benefits the patients in several aspects such as less post-operative pain, shorter recovery period, fewer complications, etc. Due to the unique characteristics of NOTES, instruments for traditional laparoscopic surgery are not suitable for NOTES and hence novel hardware design is necessary for facilitating system development. This paper gives an overview of the state of the arts in the development of surgical instruments for NOTES, particularly with a focus on the promising robotic endoscopes. [ABSTRACT FROM AUTHOR]

A family of passive echogenic markers is presented by which the position and orientation of a surgical instrument can be determined in a 3-D ultrasound volume, using simple image processing. Markers are attached near the distal end of the instrument so that they appear in the ultrasound volume along with the instrument tip. They are detected and measured within the ultrasound image, thus requiring no external tracking device. This approach facilitates imaging instruments and tissue simultaneously in ultrasound-guided interventions. Marker-based estimates of instrument pose can be used in augmented reality displays or for image-based servoing. Design principles for marker shapes are presented that ensure imaging system and measurement uniqueness constraints are met. An error analysis is included that can be used to guide marker design and which also establishes a lower bound on measurement uncertainty. Finally, examples of marker measurement and tracking algorithms are presented along with experimental validation of the concepts. [ABSTRACT FROM PUBLISHER]

Off-the-shelf industrial robotic technologies have achieved significant advancements in the past several decades in terms of mechanics and automation performances. We are expecting to take advantage of the industrial robots for assisting surgeons in surgeries and quick prototyping a robotic surgery system. In precise computer-assisted surgeries (CASs), such as pelvic-acetabular surgery, eye surgery, or neurosurgery, it is extremely important to position the tools accurately and precisely for surgical operations. Some of the industrial robotics arms are able to achieve good repeatability and dexterity while positioning the surgical tools. To enable the application of industrial robots in the surgical rooms, there are several other essential modules to be integrated to the robotic surgery systems, such as real-time navigation system, surgical planning system, and surgeon-guidance system. In this paper, we review the existing studies on the medical robots including the ones using industrial robots, and then investigate the essentials for using industrial robots in computer-integrated surgery. [ABSTRACT FROM AUTHOR]

Abstract: We design a compact ring resonator of surface modes based on photonic crystals (PCs). The structure is formed by sandwiching a surface mode ring waveguide (SMRW) into two parallel surface mode waveguide (SMW) based on two dimensional (2D) PCs. The SMRW is created on the surface of a circular photonic crystal (CPC) structure, where the wave propagates with high transmission efficiency. As a fundamental mode is introduced in the input SMW, at certain frequencies, the SMRW modes are enhanced because of resonance and the light-waves are coupled to the output SMW. It is demonstrated by the simulation results that the surface mode ring resonator has a low radiation loss with a very small size because of the good wave-guiding of surface mode based on PCs, and can be used in the future wavelength division multiplex (WDM) optics communication systems. [Copyright &y& Elsevier]

Abstract: As an important component of scanning near-field optical microscope (SNOM), optical fibre nanoprobe has been applied to many fields extensively. A melt-stretched etching method is proposed to produce optical fibre nanoprobe with low cost. Firstly, optical fibre tip with micrometer-sized diameter is created by the melt-stretched measure. Next, it is dipped into hydrofluoric acid (HF), and a fine optical fibre nanoprobe will be made after a short-time etching. Owing to the taper structure of tip, it can be etched again in acid if a nanoprobe is not constructed when the first etching is completed. In addition, optical fibre nanoprobe is applied to spectral investigation, and the fluorescence spectroscopy of rhodamine B (Rh B) solution is collected by an optical investigation system with a bifurcated fibre. [Copyright &y& Elsevier]

Abstract: A novel three-port channel add/drop filter consisting of two waveguides and two cavities is proposed. One is used for a resonant tunneling-based channel add/drop operation from the bus waveguide to the add/drop waveguide, while the other is used to realize the wavelength-selective reflection feedback in the bus waveguide. By means of coupled mode theory in time, the conditions to achieve 100% add efficiency are derived thoroughly. Based on these theoretical analysis, the channel add filter and some other multi-channel filters are designed in two-dimensional photonic crystals (2D PCs) with square lattice of dielectric rods in air. The numerical results by using the finite-difference time-domain (FDTD) method demonstrate almost complete channel add/drop tunneling at resonance via the three-port systems. [Copyright &y& Elsevier]

In the paper, a novel power-splitting scheme based on two dimensional photonic crystal (2D PhC) is proposed. The structure can be divided into three sections, including the input waveguide, coupling region, and output region, and the latter two sections consist of two parallel waveguides placed in proximity. The operation principle of the splitter is that only one of the super-modes splitting from the directional coupler can propagate through coupling region in the frequency range of interest. The radius of air holes next to the guiding region in coupling region is increased to avoid the acute back reflection at the entrance to the input waveguide induced by the modes mismatch between the input waveguide and coupling region. While in output region, the radius of these corresponding air holes is also increased so that the two splitting super-modes have same propagation constants to avoid the coupling between the two output waveguides. Moreover, as the length of coupling region is varied, its influence on the splitting performance is discussed, and it is verified that the relationship between the splitter length and bandwidth has a trade-off. [ABSTRACT FROM AUTHOR]

Registration is an essential problem in image-guided surgery (IGS) since it brings different involved coordinate frames together. Nonrigid or deformable registration still faces many challenges, such as two point sets (PSs) are partially overlapped. To tackle the challenges in the nonrigid registration, we introduce a new two-step point-based registration pipeline that includes two steps. In the first step, the rigid transformation between the two spaces is recovered where the orientation vectors are adopted. In the second step, built on the nonrigid coherent point drift (CPD) approach, the anisotropic positional noise is also assumed. Registration results on the human liver verify the proposed approach’ great improvements over the other methods. First, the rotation and translation are recovered with smaller error values than the existing methods. Second, our registration method’s performance is much more robust to the partial overlapping between two PSs. Third, the two-step registration framework achieves the best performances in most test cases when there is a localization error in acquiring the intraoperative data. Note to Practitioners—A novel registration approach is presented for image-guided liver surgery (LGLS). Compared with existing nonrigid registration methods, two significant changes (or improvements) exist in the proposed registration framework: 1) the normal vectors are extracted and utilized in the rigid registration step and 2) the anisotropic positional uncertainties are considered. In both steps, the registration problems are formulated as a maximum likelihood (ML) problems and dealt with the expectation-maximization (EM) technique. In both steps, the matrix form of the updated positional covariance is provided and can speed up the computational process. The readers are reminded that with extra information and a more general positional error assumption, our approach demonstrates improved performances in the case of partial-to-full alignment. [ABSTRACT FROM AUTHOR]

In endoscopic submucosal dissection (ESD), the gastrointestinal (GI) tract warrants the surgical instruments to navigate through a long, narrow and tortuous endoscope. This poses a great challenge in developing ESD instruments with small dimensions, flexibility, and high distal dexterity. In this work, we propose the first Transendoscopic Flexible Parallel Continuum Robotic mechanism to develop a miniature dexterous flexible-stiff-balanced Wrist (FPCW). Besides, it can steer multifunctional instruments of diameters 2.5 mm to 3.5 mm, including the electrosurgical knife, injection needle, and forceps. Our FPCW instruments are adaptable to commercially available dual-channel endoscopes (diameter: <12 mm, channel width: 2.8 mm and around 3.8 mm). Furthermore, we develop a surgical telerobotic system, called DREAMS (Dual-arm Robotic Endoscopic Assistant for Minimally Invasive Surgery), by using our smallest FPCW instruments for bimanual ESD procedures. First, we conduct a series of experiments to determine the FPCW's design and kinematics parameters and to verify the mechanical properties of the FPCW instruments' prototypes, including workspace, stiffness, strength, and teleoperation accuracy. Second, we validate the functionality of the FPCW instruments through ex-vivo tests by performing ESD steps on porcine stomachs. Finally, we perform an invivo test on a live porcine model and showcase that our developed DREAMS can be teleoperated intuitively to perform bimanual ESD efficiently with an average dissection speed of 108.95 mm2/min at the greater curvature in gastric body, which demonstrates that our DREAMS has satisfactory maneuverability as well as accuracy and is more competitive than counterpart robotic systems. [ABSTRACT FROM AUTHOR]

Higher order hierarchical wrinkle patterns may extend the functionalities and enable new capabilities in the devices created, but current transfer‐based methods are often complex and tedious. This work develops a transfer‐free method to generate hierarchical wrinkle patterns in MXene thin films via controlled deflation of a latex balloon substrate by exploiting its thermal‐elastic properties. This work generates four different wrinkle patterns with varying strain sensitivity: 2D (GF = 0.593), 1D1D (GF = 0.0979), 2D1D (GF = 0.0165), and 2D2D (GF = 0.545). Taking advantage of the small strain response exhibited by the 2D1D electrode, this work fabricates stretchable stain‐insensitive contact sensors where its behavior can be tuned by varying the thickness of the spacer. When the spacer is 0.16 mm thick, the sensor is observed to have a pressure sensitivity of 0.0922, 0.109, and 0.112 kPa−1 at 0%, 25% and 50% stretching states respectively at pressures of <2500 Pa. When the spacer is 0.32 mm thick, the sensor is observed to have a pressure sensitivity of 0.154, 0.185, and 0.233 kPa−1 under 0%, 25% and 50% strain respectively between the pressure range of 2900–5200 Pa. [ABSTRACT FROM AUTHOR]

Higher order hierarchical wrinkle patterns may extend the functionalities and enable new capabilities in the devices created, but current transfer‐based methods are often complex and tedious. This work develops a transfer‐free method to generate hierarchical wrinkle patterns in MXene thin films via controlled deflation of a latex balloon substrate by exploiting its thermal‐elastic properties. This work generates four different wrinkle patterns with varying strain sensitivity: 2D (GF = 0.593), 1D1D (GF = 0.0979), 2D1D (GF = 0.0165), and 2D2D (GF = 0.545). Taking advantage of the small strain response exhibited by the 2D1D electrode, this work fabricates stretchable stain‐insensitive contact sensors where its behavior can be tuned by varying the thickness of the spacer. When the spacer is 0.16 mm thick, the sensor is observed to have a pressure sensitivity of 0.0922, 0.109, and 0.112 kPa−1 at 0%, 25% and 50% stretching states respectively at pressures of <2500 Pa. When the spacer is 0.32 mm thick, the sensor is observed to have a pressure sensitivity of 0.154, 0.185, and 0.233 kPa−1 under 0%, 25% and 50% strain respectively between the pressure range of 2900–5200 Pa. [ABSTRACT FROM AUTHOR]

Purpose: The combined small-cell lung cancer (c-SCLC) is rare and has unique clinicopathological futures. The aim of this study is to investigate 18F-FDG PET/CT parameters and clinicopathological factors that influence the prognosis of c-SCLC. Methods: Between November 2005 and October 2014, surgical-resected tumor samples from c-SCLC patients who received preoperative 18F-FDG PET/CT examination were retrospectively reviewed. The maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) were used to evaluate metabolic parameters in primary tumors. The survivals were evaluated with the Kaplan–Meier method. Univariate and multivariate analyses were used to evaluate potential prognostic factors. Results: Thirty-one patients were enrolled, with a median age of 62 (range: 35 − 79) years. The most common mixed component was squamous cell carcinoma (SCC, n = 12), followed by large-cell carcinoma (LCC, n = 7), adenocarcinoma (AC, n = 6), spindle cell carcinoma (n = 4), adenosquamous carcinoma (n = 1) and atypical carcinoid (n = 1). The median follow-up period was 53.0 (11.0–142.0) months; the 5-year overall survival (OS) and progression-free survival(PFS) rate were 48.4% and 35.5%, respectively. Univariate survival analysis showed that gender, smoking history, tumor location were associated with PFS (P = 0.036, P = 0.043, P = 0.048), SUVmax and TNM stage were closely related to PFS in both Mixed SCC and non-SCC component groups (P = 0.007, P = 0.048). SUVmax, smoking history, tumor size and mixed SCC component were influencing factors of OS in patients (P = 0.040, P = 0.041, P = 0.046, P = 0.029). Multivariate survival analysis confirmed that TNM stage (HR = 2.885, 95%CI: 1.323–6.289, P = 0.008) was the most significantly influential factor for PFS. High SUVmax value (HR = 9.338, 95%CI: 2.426–35.938, P = 0.001) and mixed SCC component (HR = 0.155, 95%CI: 0.045–0.530, P = 0.003) were poor predictors for OS. Conclusion: Surgical-resected c-SCLCs have a relatively good prognosis. TNM stage is the most significant factor influencing disease progression in surgical-resected c-SCLCs. SUVmax and mixed NSCLC components within c-SCLCs had a considerable influence on the survival. Both high SUVmax and mixed SCC component are poor predictors for patients with c-SCLCs. [ABSTRACT FROM AUTHOR]

Glioblastoma multiforme (GBM) is a very aggressive and infiltrative brain tumor with a high mortality rate. There are radiomic models with handcrafted features to estimate glioblastoma prognosis. In this work, we evaluate to what extent of combining genomic with radiomic features makes an impact on the prognosis of overall survival (OS) in patients with GBM. We apply a hypercolumn-based convolutional network to segment tumor regions from magnetic resonance images (MRI), extract radiomic features (geometric, shape, histogram), and fuse with gene expression profiling data to predict survival rate for each patient. Several state-of-the-art regression models such as linear regression, support vector machine, and neural network are exploited to conduct prognosis analysis. The Cancer Genome Atlas (TCGA) dataset of MRI and gene expression profiling is used in the study to observe the model performance in radiomic, genomic, and radiogenomic features. The results demonstrate that genomic data are correlated with the GBM OS prediction, and the radiogenomic model outperforms both radiomic and genomic models. We further illustrate the most significant genes, such as IL1B, KLHL4, ATP1A2, IQGAP2, and TMSL8, which contribute highly to prognosis analysis. [ABSTRACT FROM AUTHOR]

This article reports a miniature, high-resolution fiber Bragg grating (FBG)-based triaxial force sensor to detect the catheter tip–tissue interaction forces. This sensor counts on a delicate three-dimensional-printed flexure comprising a cylinder with an inner elliptical cavity for detecting lateral forces and a hybrid elastomer to enhance axial elasticity for improving z-directional force sensitivity. Four suspended optical fibers inscribed with FBG each are deployed inside the flexure. Such configurations are designed to maximize the decoupling among three force components, achieve temperature compensation, and raise the sensor's robustness under biofluid-filled environments. The sensor characterization results indicate a high resolution of 0.52 and 0.64 mN for both lateral forces within –0.8 to 0.8 N and 0.63 mN for axial direction force within 0–0.8 N. Validation with dynamic loadings along different azimuth angles shows that the sensor can provide a high-accuracy measurement of three force components with an rms error of less than 3.00%. Temperature-induced errors for force detection are considerably alleviated, showing less than 6.5% in the range of 25 °C–50 °C. Ex vivo experiments on a swine heart further validate the performances of the designed sensor. [ABSTRACT FROM AUTHOR]

This paper presents a disposable fiber Bragg grating (FBG) based tridirectional force/torque sensor mountable at the end of the tip of the aspiration instruments for detecting instrument–tissue interaction force/torque. The sensor utilizes an inexpensive three-dimensional (3-D) printed elastomer with an annular diaphragm, which is sensitive to axial force (Fz) and torques (Mx and My). Four suspended optical fibers inscribed with an FBG each have been fixed on two ends of the elastomer to simultaneously sense and decouple force/torque-induced diaphragm deformation. The associated sensing theoretical model and force-torque decoupling principle with temperature compensation have been derived. Calibration experiments demonstrate a high resolution of 8.8 mN within the range of 0–2 N for the axial force detection. Dynamic performances of the designed sensor have been evaluated in comparison with the commercial force sensor. The average relative errors of force/torque components are less than 4.4% of full-scale range. The maximum temperature drift-caused errors of the force/torque components within the range of 30 °C–45 °C are –0.1340 N, 0.0084 N·mm, and 0.0300 N·mm, respectively. In vivo experiments on a cadaver head have been performed to further validate the feasibility and effectiveness of the designed sensor for real-time monitoring of the interaction force. [ABSTRACT FROM AUTHOR]

Conventional needle-based approaches in intravitreal drug delivery carry needle-stick-injury risk and could scare patients (belonephobia). Alternatively, our group has explored the application of an electromagnetic needleless injector in this paper. This work aims to improve intravitreal drug delivery, which in the future could assist physicians with automation and benefit patients by providing a needleless approach. Electromagnetic needleless intravitreal injections lack quantification studies. We investigate the delivery properties of the needleless injector where the characterization can be used to refine the design parameters of the prototype in subsequent iterations. Experiments were performed to characterize the injectant delivered from the electromagnetic needleless injector. Penetration tests were conducted to observe the influences of various injection barriers and tissues. Ultrasonic imaging modality was explored for future applications of the prototype. The dispersion of the injectant was controllable where injection depth and distribution is dependent on the input voltage. The synthetic barriers highlighted significant energy losses for penetration (maximum velocity falls from 4.46 to 1.57 mm/s with a 0.1-mm barrier). The biological barriers were difficult to penetrate with the current prototype. Our results indicate that the current electromagnetic injector offers controllable dispersion (depth and distribution) correlated with input voltages, which should have increased injection power for use with biological tissue. Ultrasonic imaging modality produced velocity profiles comparable to the optical approach which is promising for future in vivo studies. The influences of injection barriers should be further investigated in in vivo experiments with ultrasonic imaging modalities. Graphical abstract . [ABSTRACT FROM AUTHOR]

Ultraviolet visible spectroscopy can realize the detection of chemical oxygen demand (COD), especially for low concentration levels due to its high sensitivity, but the issue of insufficient real water sample data has always been a challenge owing to the low probability of occurrence of actual water pollution events. However, in existing methods, generated absorption spectra do not conform to actual situations as the former neglect the actual spectral characteristics. On the other hand, the diversity and complexity are restricted because the information in one-dimensional data is not enough for direct spectral generation. This study proposed a spectral sample generation method based on the variational modal decomposition and generative adversarial network (VMD–GAN). First, the VMD algorithm was utilized to separate principal components and residuals of absorption spectra. Among them, the GAN was used to generate new principal components to ensure that the major spectral characteristics of actual water samples are not lost. The corresponding residuals were then obtained by adjusting the parameters of a three-order Gaussian fitting function, which is more beneficial than the direct use of GAN in the aspect of diversity and complexity. Based on the spectral reconstruction with new principal components and residuals, various absorption spectra were generated more coincident with actual situations. Finally, the effectiveness of this method was evaluated by establishing regression models and predicting COD for actual water samples. In all, the insufficient water sample data can be expanded for a better performance in modeling and analysis of water pollution using the proposed method. [ABSTRACT FROM AUTHOR]

Video-assisted transoral tracheal intubation (TI) necessitates using an endoscope that helps the physician insert a tracheal tube into the glottis instead of the esophagus. The growing trend of robotic-assisted TI would require a medical robot to distinguish anatomical features like an experienced physician which can be imitated by utilizing supervised deep-learning techniques. However, the real datasets of oropharyngeal organs are often inaccessible due to limited open-source data and patient privacy. In this work, we propose a domain adaptive Sim-to-Real framework called IoU-Ranking Blend-ArtFlow (IRB-AF) for image segmentation of oropharyngeal organs. The framework includes an image blending strategy called IoU-Ranking Blend (IRB) and style-transfer method ArtFlow. Here, IRB alleviates the problem of poor segmentation performance caused by significant datasets domain differences, while ArtFlow is introduced to reduce the discrepancies between datasets further. A virtual oropharynx image dataset generated by the SOFA framework is used as the learning subject for semantic segmentation to deal with the limited availability of actual endoscopic images. We adapted IRB-AF with the state-of-the-art domain adaptive segmentation models. The results demonstrate the superior performance of our approach in further improving the segmentation accuracy and training stability. [ABSTRACT FROM AUTHOR]

Transformer-based methods have led to the revolutionizing of multiple computer vision tasks. Inspired by this, we propose a transformer-based network with a channel-enhanced attention module to explore contextual and spatial information in non-contrast (NC) and contrast-enhanced (CE) computed tomography (CT) images for pulmonary vessel segmentation and artery-vein separation. Our proposed network employs a 3D contextual transformer module in the encoder and decoder part and a double attention module in skip connection to effectively finish high-quality vessel and artery-vein segmentation. Extensive experiments are conducted on the in-house dataset and the ISICDM2021 challenge dataset. The in-house dataset includes 56 NC CT scans with vessel annotations and the challenge dataset consists of 14 NC and 14 CE CT scans with vessel and artery-vein annotations. For vessel segmentation, Dice is 0.840 for CE CT and 0.867 for NC CT. For artery-vein separation, the proposed method achieves a Dice of 0.758 of CE images and 0.602 of NC images. Quantitative and qualitative results demonstrated that the proposed method achieved high accuracy for pulmonary vessel segmentation and artery-vein separation. It provides useful support for further research associated with the vascular system in CT images. The code is available at https://github.com/wuyanan513/Pulmonary-Vessel-Segmentation-and-Artery-vein-Separation. [ABSTRACT FROM AUTHOR]

In this paper, the high precision control problem is investigated for the nonlinear discrete system with modeling uncertainties. A new method based on nonlinear U model is proposed for sliding mode control, then based on which a new sliding mode observer is proposed firstly and a new adaptive reaching law is designed. The convergence of the designed sliding mode observer and the reach ability of the designed adaptive reaching law is proved respectively, then based on which and the Lyapunov's stability theory the stability of the control system is proved. The observation error problem is also discussed, it is shown that the proposed sliding mode observer has a smaller observation error than the traditional method. Finally, two numerical example is given to illustrate the feasibility and superiority of the proposed design scheme. [ABSTRACT FROM AUTHOR]

This paper presents a sensor fusion-based surgical instrument tracking system which uses multiple monocular modules. The system is an optical tracking system, which has been widely utilized in the image-guide surgery because of its high accuracy and precision. However, the line-of-sight occlusion problem which remains unresolved in current systems frustrates surgeons during the operation. To address this challenge, we propose a surgical instrument tracking system based on multiple monocular modules. The rationale is to enable the system to track the surgical instruments inside the surgical site from different views. Three sensor fusion algorithms are proposed to integrate all sensor data from the multimodule system. In order to show the feasibility of the tracking system, simulations and comparison experiments have been carried out. The intensive investigation results give a practical instruction to the real implementation of the proposed system in image-guided interventions. Moreover, an image-guided surgical trial by using a cadaver head has been carried out to validate the feasibility of the proposed system and the tracking algorithms. The results from both the simulation and the cadaver trial have shown the effectiveness of the proposed robust fusion algorithm. Note to Practitioners—Optical tracking system (OTS) for image-guided surgery has suffered from line-of-sight (LoS) occlusion and field-of-view (FoV) limitation problems for a long time; nevertheless, no satisfactory solution has been given yet. In the real-world practice, surgeons and assistants have to manually adjust the position and orientation of the optical tracker during operation. This interrupts the surgery process and degrades the efficiency of the surgical procedure. Instead of using one tracker for the image-guided surgery, our approach is to utilize distributed modular trackers to avoid LoS occlusion and maintain FoV of the OTS. Based on our previous work, this paper is to provide an optimal fusion algorithm that takes the advantage of the multiple modules and validate the system in both the simulation and the real-world surgical environment. [ABSTRACT FROM AUTHOR]

This paper introduces a systematical interval-based framework of inherent uncertainties and pose evaluation for a class of soft continuum robots driven by flexible shafts. A more general model of continuum robots driven by shaft tendons is extended from prior kinematic models. On top of the proposed model, the interval-based analysis is presented to analyze and characterize the pose of continuum robots considering uncertainties in kinematic parameters and joint inputs. A 3-D printed bending actuator driven by a flexible shaft is evaluated for case study based on the proposed interval-valued framework. This paper investigates and compares a couple of refinement methods and proposes a new way of sensitivity analysis of model parameters based on interval arithmetic. The kinematic and mechanics parameters are measured and identified experimentally with a representation of intervals. The in-plane motion experiment validates that the computed bounds can enclose all the measured tip positions with consideration of the measurement uncertainty. The method is also validated when external loading is exerted. Note to Practitioners—With the fast development of soft robotics, the increasing number of soft robotic manipulators show great potentials of application in industries such as agriculture, biomedicine, home automation, manufacturing, logistics, and domestic service. Thanks to the mechanical compliance, soft manipulators demonstrate environmental adaptability at the cost of very precise positioning. However, the guaranteed bounds of the reaching range are valuable in order to provide users a good knowledge of the product performance, which is the motivation of this paper. This paper provides not only a method and framework based on interval analysis to evaluate the pose of soft actuators, but also a case study of uncertainty interval characterization procedure which is domain-specific for soft actuators. The presented method framework can be implemented for continuum manipulators and soft actuators as well as any other robotic devices featured by such flexible components. [ABSTRACT FROM AUTHOR]

Image guidance during minimally invasive intravascular interventions is primarily achieved based on X-ray fluoroscopy, which has several limitations including limited 3-D imaging capability, significant doses of radiation to operators, and lack of contact force measurement between the cardiovascular tissue and interventional tools. Ultrasound imaging can be adopted to complement or possibly replace 2-D fluoroscopy for intravascular interventions due to its portability, safety to use, and the ability of providing depth information. However, it is challenging to precisely visualize catheters and guidewires in the ultrasound images. In this paper, we propose a novel method to figure out both the position and orientation of the catheter tip in 2-D ultrasound images in real time by detecting and tracking a passive marker attached to the catheter tip. Moreover, the contact force can be estimated simultaneously as well via measuring the length variation of the marker. A geometrical model-based method is introduced to detect the initial position of the marker, and a Kanade–Lucas–Tomasi-based algorithm is developed to track the position, orientation, and length of the marker. The ex vivo experiment results validate the effectiveness of the proposed approach in automatically locating the catheter tip in ultrasound images and its capability of sensing the contact force. Therefore, it can be concluded that the presented method can be utilized to better facilitate operators during intravascular interventions. Note to Practitioners—This paper is motivated by the vision-based force sensing mechanism. A coil spring marker is used to visualize and locate the catheter tip in ultrasound images. The metallic helical structure of the marker can result in remarkable features in 2-D in-plane ultrasound images. A geometrical model-based detection algorithm is proposed to detect the passive marker in initial frame regardless of its length and orientation variation. A prediction–detection-combined tracking algorithm is developed to automatically track the catheter tip for the subsequent frames in real time. Most importantly, the distal force can be simultaneously estimated due to the length variation of the passive marker. The sensed force can be fed back to a robotic catheterization system during intravascular interventions. [ABSTRACT FROM AUTHOR]

This work presents a novel soft actuator with a 3D-printed elastic body based on a fused-deposition-modeling technique and with tendon actuation based on flexible shafts, which allow push, pull, and twist torque transmissions. The combination of the soft body and flexible shaft furnishes an easy-making, modular and functional unit that possesses softness and enables three degrees of freedom. We derive the kinematics and statics of the actuator based on the assumption of piecewise constant curvature, and identify the parameters experimentally. To understand the performance of the soft actuator in different design and fabrication settings, extensive experiments are performed to compare different shapes of cross sections, infill densities, infill patterns, dentation structures and moment arms in terms of generating forces under the same pulling forces. In addition, experimental validations are performed to characterize other properties such as workspace, hysteresis, pushing force, transmitted torque, and tip force under both bending and twisting. Finally, three potential applications, i.e., a soft robotic hand, a multisegment continuum robot, and a miniaturized drilling device, are prototyped and presented experimentally where the flexibility endowed by the shafts is demonstrated and highlighted. The scalability and modularity are also showcased in the three applications. [ABSTRACT FROM AUTHOR]

This paper develops a novel shared control scheme for online-switching tele-operated and autonomous system with time-varying delays. Type-2 Takagi–Sugeno (T–S) fuzzy model is used to describe the dynamics of master and slave robots in this system. A novel non-singular fast terminal siding mode (NFTSM)-based algorithm combined with an extended wave-based time domain passivity approach (TDPA) is presented to enhance the master–slave motion synchronization in the tele-operated mode and reference-slave motion synchronization in the autonomous mode, while simultaneously ensuring the stability of the overall system in the presence of arbitrary time delays. In addition, based on the Type-2 Fuzzy model, a new torque observer is designed to estimate the external torques and then the torque tracking method is employed in the control laws to let the slave apply the designated force to further improve the operator’s force perception for the environment. The stability of the closed-loop system is proven using the Lyapunov–Krasovskii functions. Finally, experiments using two haptic devices prove the superiority of the proposed strategy. [ABSTRACT FROM AUTHOR]

Data-defect would affect the data quality and the analysis results of data mining. This paper presents a data-defect inspection method with kernel-neighbor-density-change outlier factor (KNDCOF). The definition of kernel neighbor density is proposed to represent the density of each object in database, and the ascending distance series (ADS) of each object is calculated based on the kernel distance between the object and its neighbors. Then, the average density fluctuation (ADF) of the object is established according to the weighted sum of the square of density difference between the object and others in ADS. Finally, the KNDCOF of the object is equal to the ratios of the ADF of the object and the average ADF of neighbors of the object. The degree of the object being an outlier is indicated by the KNDCOF value. The experiments are performed on three real data sets to evaluate the effectiveness of the proposed method. The experimental results verify that the proposed method has higher quality of data-defect inspection and does not increase the time complexity.

Note to Practitioners–Data-defect inspection is an important procedure of data preprocessing for a real industrial process. This paper presents a data-defect inspection method with kernel-neighbor-density-change outlier factor to identify the outliers, and addresses the challenges associated with the strong correlation and the nonlinearity of the industrial data. The proposed method calculates the outlier factor for each object, which quantifies how outlying it is. The outlier factor is based on the density difference between the object and its neighbors. The larger the outlier factor of an object is, the higher the outlierness of the object is. The proposed method could be wildly used in an industrial complex data set with different density regions. In the industrial field, engineers can deal with the objects with high outlier factor values based on the actual requirements. [ABSTRACT FROM AUTHOR]

This paper develops data-driven Type-2 Takagi–Sugeno (T–S) fuzzy modeling and control for bilateral teleoperation with dynamic uncertainties and time-varying delays. The Type-2 T–S fuzzy model identified based on input–output data samples describes the nonlinear teleoperation system by a weighted sum of a group of linear local models, which offers a platform to design robust control algorithms by means of mature linear theories. The fuzzy-model-based four-channel control laws are proposed to guarantee the motion synchronization and enhance the operator's force perception for the environment when the time-varying delays and large dynamic uncertainties, especially the gravity of a heavy end effector of the slave, exist. Markov processes are applied to model the time delays. The stability of the closed-loop system is proved by using the Lyapunov–Krasovskii functions. All the conditions are expressed as linear-matrix inequalities (LMI). By using the MATLAB LMI toolbox, the optimized control gains for each of the fuzzy rules are derived to achieve the optimal performance. Finally, experiments based on an experimental platform consisting of two haptic devices prove the superiority of the proposed strategy through comparison with previous work. [ABSTRACT FROM PUBLISHER]

• Focus on the information loss problem in tracking technologies for surgical navigation systems. • Survey the existing solutions to information loss in tracking surgical instruments. • Information fusion technology to improve accuracy, precision, and stability. • Future research trends on information fusion during surgical navigation. Surgical navigation technology provides minimally invasive surgery (MIS) with the relative pose relationships amongst medical images, surgical instruments, and lesions. On the other hand, traditional operation procedures depend heavily on direct surgical field exposure. Consequently, introducing surgical navigation can enable surgeons to operate more accurately and efficiently. A tracking system is a core enabling technology of a surgical navigation system. In this paper, after reviewing the tracking technologies, we compare and analyze their pros and cons, and find that information loss is a common challenge. The information loss problem is an inherent drawback in mono-modality surgical navigation systems. It is characterized by physical constraints, attenuation, breakdown of signal, and accuracy instability of the tracking algorithms. This review focuses on the information loss problem in tracking technologies for surgical navigation systems. Furthermore, we survey the existing solutions that aim at tackling the information loss problem, especially in the information fusion of surgical tracking technologies, and we also summarize their key improvements and limitations. Particular attention has been given to the modalities, approaches, objectives, and surgical application scenarios, which can improve the accuracy, precision, and stability of surgical navigation systems. Finally, future research trends directed at improving the information loss problem are discussed, i.e., tight integration of sensing technology, augmented reality for visualization in surgical tracking, stable high-speed 5G networks for telesurgery, strong intelligence and affordable service. [ABSTRACT FROM AUTHOR]

Due to the simplicity and high reliability, brushless dc (BLDC) motors are widely used in space application. High-reliability levels are the vital aspect for ensuring the long-term stable operation of the BLDC motor system, which is used in aerospace applications. The fault-tolerant control of the BLDC motor is of great importance for its continuous operating capacity even under the faulty situation. This paper proposes a fault-tolerant topology composed of an additional phase leg and a fault-protective circuit for the high-speed low-inductance BLDC motor. Based on the analysis of the overcurrent and overvoltage phenomenon after the switch faults, a novel fault isolation and system reconfiguration method is presented. The method can achieve safe isolation and reconfiguration to avoid the secondary fault caused by direct switch of the redundant switch and the faulty switch after the fault-diagnosis process. Both simulation and experimental results confirm the feasibility and effectiveness of the proposed method. [ABSTRACT FROM PUBLISHER]

Robot manipulators are increasingly used in minimally invasive surgery (MIS). They are required to have small size, wide workspace, adequate dexterity and payload ability when operating in confined surgical cavity. Snake-like flexible manipulators are well suited to these applications. However, conventional fully actuated snake-like flexible manipulators are difficult to miniaturize and even after miniaturization the payload is very limited. The alternative is to use underactuated snake-like flexible manipulators. Three prevailing designs are tendon-driven continuum manipulators (TCM), tendon-driven serpentine manipulators (TSM) and concentric tube manipulators (CTM). In this paper, the three designs are compared at the mechanism level from the kinematics point of view. The workspace and distal end dexterity are compared for TCM, TSM and CTM with one, two and three sections, respectively. Other aspects of these designs are also discussed, including sweeping motion, scaling, force sensing, stiffness control, etc. From the results, the tendon-driven designs and concentric tube design complement each other in terms of their workspace, which is influenced by the number of sections as well as the length distribution among sections. The tendon-driven designs entail better distal end dexterity while generate larger sweeping motion in positions close to the shaft. [ABSTRACT FROM AUTHOR]