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Abstract: Abstract A 6-DOF cooperative manipulator is used for human spinal deformity detection. In order to ensure the scanning quality of spinal deformity and improve the solution rate and speed of inverse motion solution of the manipulator, an inverse kinematics analytical method based on spherical geometry is proposed in this paper. We take the AUBO-i5 collaborative manipulator as the research object, which combines the rapidity of analytical solution with the flexibility of spherical solution. In the Robot Operating System, the simulation experiment solves the inverse kinematics of 10 000 sets of randomly generated postures. The success rate and time-consuming of the solution are calculated. Compared with the two commonly used inverse kinematics solving algorithms, TRAC-IK and KDL, this method has obvious advantages in terms of success rate and average time-consuming. PubDate: 2022-05-16
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Abstract: Abstract Medical image registration is widely used in image-guided therapy and image-guided surgery to estimate spatial correspondence between planning and treatment images. However, most methods based on intensity have the problems of matching ambiguity and ignoring the influence of weak correspondence areas on the overall registration. In this study, we propose a novel general-purpose registration algorithm based on free-form deformation by non-subsampled contourlet transform and saliency map, which can reduce the matching ambiguities and maintain the topological structure of weak correspondence areas. An optimization method based on Markov random fields is used to optimize the registration process. Experiments on four public datasets from brain, cardiac, and lung have demonstrated the general applicability and the accuracy of our algorithm compared with two state-of-the-art methods. PubDate: 2022-05-16
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Abstract: Abstract Mobile robot local motion planning is responsible for the fast and smooth obstacle avoidance, which is one of the main indicators for evaluating mobile robots’ navigation capabilities. Current methods formulate local motion planning as a unified problem; therefore it cannot satisfy the real-time requirement on the platform with limited computing ability. In order to solve this problem, this paper proposes a fast local motion planning method that can reach a planning frequency of 500 Hz on a low-cost CPU. The proposed method decouples the local motion planning as the front-end path searching and the back-end optimization. The front-end is composed of the environment topology analysis and graph searching. The back-end includes dynamically feasible trajectory generation and optimal trajectory selection. Different from the popular methods, the proposed method decomposes the local motion planning into four sub-modules, each of which aims to solve one problem. Combining four sub-modules, the proposed method can obtain the complete local motion planning algorithm which can fastly generate a smooth and collision-free trajectory. The experimental results demonstrate that the proposed method has the ability to obtain the smooth, dynamically feasible and collision-free trajectory and the speed of the planning is fast. PubDate: 2022-05-16
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Abstract: Abstract The composite structure with the dielectric elastomer and soft materials is the main form of the actuators in soft robots. However, the theoretical model is hard to obtain due to the nonlinear large deformation of materials. In this paper, a new composite element model is established based on the absolute nodal coordinate formulation. The consistent deformation conditions at the contact interface between two thin plates are deduced. The hyperelastic constitutive model and the dielectric elastomer constitutive model are introduced for the two thin plates. Then the dynamic model is established to study the dynamic behaviors of the composite flexible structure with various parameters. The results show that the nonlinear deformation appears obviously when the flexible composite plate structure is driven by various voltages. And the warping deformation becomes more obvious with the increases of the voltage. The width and thickness of the driven thin plate influence the stability of the whole structure. With the decrease of the width or thickness, the deformation of the structure is more consistent with obvious periodicity, and the control performance is improved. Finally, the structural parameters of the composite structures are optimized to improve the control performance based on the dynamic performance. And smaller width and thickness parameters are preferred to obtain better performance in the design of flexible actuator of soft robot. PubDate: 2022-05-16
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Abstract: Abstract As a kind of physical signals that could be easily acquired in daily life, photoplethysmography (PPG) signal becomes a promising solution to biometric identification for daily access management system (AMS). State-of-the-art PPG-based identification systems are susceptible to the form of motions and physical conditions of the subjects. In this work, to exploit the advantage of deep learning, we developed an improved deep convolutional neural network (CNN) architecture by using the Gram matrix (GM) technique to convert time-serial PPG signals to two-dimensional images with a temporal dependency to improve accuracy under different forms of motions. To ensure a fair evaluation, we have adopted cross-validation method and “training and testing” dataset splitting method on the TROIKA dataset collected in ambulatory conditions. As a result, the proposed GM-CNN method achieved accuracy improvement from 69.5% to 92.4%, which is the best result in terms of multi-class classification compared with state-of-the-art models. Based on average five-fold cross-validation, we achieved an accuracy of 99.2%, improved the accuracy by 3.3% compared with the best existing method for the binary-class. PubDate: 2022-05-16
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Abstract: Abstract The substantia nigra pars reticulate (SNr), which plays a pivotal role in motor control, is the key structure in integrating information for cortex, basal ganglia and thalamus. Abnormal gait and posture deficits can be reversed by SNr deep brain stimulation (DBS) in certain Parkinson’s disease cases. However, functional characterization of SNr, which is the key for the optimization of DBS effect, remains elusive. In current study, we recorded extracellular single unit in SNr of urethane anesthetized rats. We have found that urethane can induce slow delta and theta oscillations in SNr local field potential. The high gamma oscillation observed is positively correlated with the occurrence of action potential. The putative GABAergic neurons have a mean firing rate of (20.82 ± 2.04) Hz, of which 65.2% display a regular firing pattern and 34.8% show irregular firing. Our results demonstrated the heterogeneous property of SNr and provided possible theoretical basis for promoting the next generation of DBS electrode design and optimization of clinical DBS parameters. PubDate: 2022-05-16
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Abstract: Abstract Fracture healing progress monitoring techniques attract global research attention due to the importance of selecting the timing of removing the fixation device. To this end, in this research, we present a piezoelectric-based smart internal fixation device, in which a piezoelectric sandwich structure is laminated to the surface of a bone plate. In the content, we explain the reasons for utilizing piezoelectric films, elaborate the mechanism of fracture monitoring, and introduce the mechanical parameters of the sensor. The simulation and experimental results show that the electrical output of the device is associated with the elastic modulus of the filler between the tested broken bones when the working load is maintained, indicating that the bone recovery progress could be successfully detected by the developed technique. PubDate: 2022-05-16
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Abstract: Abstract The high frequency ventilation (HFV) can well support the breathing of respiratory patient with 20%–40% of normal tidal volume. Now as a therapy of rescue ventilation when conversional ventilation failed, the HFV has been applied in the treatments of severe patients with acute respiratory failure (ARF), acute respiratory distress syndrome (ARDS), etc. However, the gas exchange mechanism (GEM) of HFV is still not fully understood by researchers. In this paper, the GEM of HFV is reviewed to track the studies in last decades and prospect for the next likely studies. And inspired by previous studies, the GEM of HFV is suggested to be continually developed with various hypotheses which will be testified in simulation, experiment and clinic trail. One of the significant measures is to study the GEM of HFV under the cross-disciplinary integration of medicine and engineering. Fully understanding the GEM can theoretically support and expand the applications of HFV, and is helpful in investigating the potential indications and contraindications of HFV. PubDate: 2022-05-16
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Abstract: Abstract This paper proposes a new type of radial expansion mechanism by adopting the scissor type telescopic design for intestinal robot to meet the requirements of the intestinal robot’s movement and residence in the intestinal tract. The robot’s maximum expansion radius is up to 25 mm, which can well adapt to the intestinal tract with different diameters. At first, the mathematical model of the scissors-type telescopic mechanism (STM) is established to further study its dynamics characteristics by theoretical analysis and simulation. Then, in order to study the coupling effect between the STM and intestinal wall, the strain-energy function of Fung-type is used to establish the constitutive model of intestinal wall. Moreover, aimed at solving the non-convergence problem caused by the selection of material parameters in general Fung-type model, the restrictions for selecting material parameters were given by using positive definite matrix theory. Furthermore, the motion coupling characteristics between the mechanism and intestinal wall were analyzed by using the finite element method. The result shows that if the expansion radius of the STM exceeds a certain value, the intestinal wall may reach its deformation limit, which means that the maximum rotating angle of the three-claw butterfly disc of STM can be decided based on the maximum deformation stress of the intestinal wall. Therefore, it provides a design basis for formulating a reasonable expansion radius in mechanism control to avoid damage to the intestinal wall. PubDate: 2022-05-16
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Abstract: Abstract Aimed at the problems of design difficulty and weak kinematic performance caused by spherical joint, a novel PRC+PRCR+RR humanoid ankle joint based on the partially decoupled spherical parallel mechanism is proposed. According to screw theory, the degree of freedom and decoupling characteristics of this mechanism are analyzed. Based on Klein formula and virtual work principle, the kinematic expressions of each link and dynamic model are established. The correctness of the dynamic model is verified by combining the virtual prototype software and the ankle pose function obtained by gait planning and Fourier fitting. The workspace of this mechanism is mapped into a two-dimensional polar coordinate system with the azimuth and elevation angles of the spherical coordinate system as parameters. The motion/force transmission index and constraint index of this mechanism are evaluated and expressed in the workspace, showing this mechanism with excellent kinematic characteristics. PubDate: 2022-05-16
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Abstract: Abstract With the development of integrate circuit and artificial intelligence, many kinds of transistors have been invented. In recent years, wide attention has been paid to the oxide thin film transistors due to its ease preparation, low cost, and suitability for mass production. Traditionally used gate dielectric film (such as silicon dioxide film) in oxide thin film transistor owns low dielectric constant, which leads to weak capacitive coupling between the gate dielectric layer and the channel layer. As a result, high voltage (10 V or more) needs to be applied on the gate electrode in order to achieve the purpose of regulating the current of channel layer. Therefore, new oxide thin film needs to be developed. In this paper, silane coupling agents (3-triethoxysilypropyla-mine) KH550 solid electrolyte film was obtained by spin coating-process. The KH550 solid electrolyte was used as gate dielectric layer to fabricate low-voltage indium zinc oxide thin film transistor. The surface topography and thickness of KH550 solid electrolyte film were characterized by atomic force microscopy and field emission scanning electron microscope, respectively. The capacitance-frequency curve of the sample was measured by impedance analyzer (Soloartron 1260A), and the electrical characteristics of the sample were analyzed by a semiconductor parameter analyzer (Keithley 4200 SCS). A maximum specific capacitance of about 7.3 µF/cm2 is obtained at 1 Hz. The transistor shows a good stability of pulse operation and negative bias voltage, the operation voltage is only 2 V, the current on/off ratio is about 1.24 × 106, and the subthreshold swing is 169.2 mV/decade. The development of KH550 solid electrolyte gate dielectric provides a novel way for the research of oxide thin film transistor. PubDate: 2022-05-16
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Abstract: Abstract This article aims to provide reference for medicine-engineering interdisciplinary research. Targeted at the scientific literature and patent literature published by Shanghai Jiao Tong University, this article attempts to set up co-occurrence matrix of medicine-engineering institutional information which was extracted from address fields of the papers, so as to construct the medicine-engineering intersection datasets. The dataset of scientific literature was analyzed using bibliometrics and visualization methods from multiple dimensions, and the most active factors, such as trends of output, journal and subject distribution, were identified from the indicators of category normalized citation impact (CNCI), times cited, keywords, citation topics and the degree of medicine-engineering interdisplinary. Research on hotspots and trends was discussed in detail. Analyses of the dataset of patent literature showed research themes and measured the degree for technology convergence of medicine-engineering. PubDate: 2022-05-16
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Abstract: Abstract To solve the problems of low efficiency and multi-solvability of humanoid manipulator Cartesian space path planning in physical human-robot interaction, an improved bi-directional rapidly-exploring random tree algorithm based on greedy growth strategy in 3D space is proposed. The workspace of manipulator established based on Monte Carlo method is used as the sampling space of the rapidly-exploring random tree, and the opposite expanding greedy growth strategy is added in the random tree expansion process to improve the path planning efficiency. Then the generated path is reversely optimized to shorten the length of the planned path, and the optimized path is interpolated and pose searched in Cartesian space to form a collision-free optimized path suitable for humanoid manipulator motion. Finally, the validity and reliability of the algorithm are verified in an intelligent elderly care service scenario based on Walker2, a large humanoid service robot. PubDate: 2022-05-04
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Abstract: Abstract Non-uniformity of light sources is one of the inevitable error factors causing poor shape recovery accuracy of photometric stereo methods under close-range lighting with quasi point lights. Semi-calibrated photometric stereo methods are required to avoid repeated, tedious and impractical photometric calibration. In this paper, two simple, concise but effective mesh-based semi-calibrated photometric stereo methods are proposed. The proposed methods extend the traditional mesh-based photometric stereo methods and further allow joint and accurate estimation of normals and non-uniform light intensities by alternatively updating normals, depth maps and intensities. Extensive experiments are conducted to validate the effectiveness and robustness of the proposed algorithms. Even under extremely severe non-uniform lighting, the proposed methods can still suppress the error and improve the shape recovery accuracy by 65.6% in real-world experiments. PubDate: 2022-05-04
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Abstract: Abstract As a new type of marine structure, floating breakwater can provide suitable water area for coastal residents. In this paper, a multi-module floating breakwater with three cylinders was designed. According to the characteristics of each module, the elastic connector was created. The cabins with functions such as living, generating electricity and entertainment were arranged. A linear spring constrained design wave (LSCDW) method for strength analysis of floating marine structures with multi-module elastic connections was proposed. The numerical model was verified by 1:50 similarity ratio in the test tank. According to the analysis of design wave and extreme wave conditions, considering the mooring loads and environmental loads and connector loads, the overall strength of breakwater was analyzed by LSCDW method. These studies can provide new insights and theoretical guidance for the design of multi-module floating structures. PubDate: 2022-05-04
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Abstract: Abstract The operation time of external trucks in a container terminal is one of port operation key performance indicators concerned by port operators, external truck operators and related government authorities. With the traffic big data combined with the operation characteristics of the container terminal, the system dynamics method is used to build the simulation model of the operation system for external trucks. The simulation results of the operation time of external trucks are consistent with the actual situation, which provides an effective way to eliminate the “black box” of the operation time of the external trucks. The model can also be applied in multiple scenarios by using the traffic big data, and the simulation results can be adopted by the relevant organizations. PubDate: 2022-05-04
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Abstract: Abstract Automatic segmentation of ischemic stroke lesions from computed tomography (CT) images is of great significance for identifying and curing this life-threatening condition. However, in addition to the problem of low image contrast, it is also challenged by the complex changes in the appearance of the stroke area and the difficulty in obtaining image data. Considering that it is difficult to obtain stroke data and labels, a data enhancement algorithm for one-shot medical image segmentation based on data augmentation using learned transformation was proposed to increase the number of data sets for more accurate segmentation. A deep convolutional neural network based algorithm for stroke lesion segmentation, called structural similarity with light U-structure (USSL) Net, was proposed. We embedded a convolution module that combines switchable normalization, multi-scale convolution and dilated convolution in the network for better segmentation performance. Besides, considering the strong structural similarity between multi-modal stroke CT images, the USSL Net uses the correlation maximized structural similarity loss (SSL) function as the loss function to learn the varying shapes of the lesions. The experimental results show that our framework has achieved results in the following aspects. First, the data obtained by adding our data enhancement algorithm is better than the data directly segmented from the multimodal image. Second, the performance of our network model is better than that of other models for stroke segmentation tasks. Third, the way SSL functioned as a loss function is more helpful to the improvement of segmentation accuracy than the cross-entropy loss function. PubDate: 2022-04-30
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Abstract: Abstract In order to solve the problem of strength instability of cemented tailings backfill (CTB) under low temperature environment (⩽ 20 °C), the strength optimization and prediction of CTB under the influence of multiple factors were carried out. The response surface method (RSM) was used to design the experiment to analyze the development law of backfill strength under the coupling effect of curing temperature, sand-cement ratio and slurry mass fraction, and to optimize the mix proportion; the artificial neural network algorithm (ANN) and particle swarm optimization algorithm (PSO) were used to build the prediction model of backfill strength. According to the experimental results of RSM, the optimal mix proportion under different curing temperatures was obtained. When the curing temperature is 10–15 °C, the best mix proportion of sand-cement ratio is 9, and the slurry mass fraction is 71%; when the curing temperature is 15–20 °C, the best mix proportion of sand-cement ratio is 8, and the slurry mass fraction is 69%. The ANN-PSO intelligent model can accurately predict the strength of CTB, its mean relative estimation error value and correlation coefficient value are only 1.95% and 0.992, and the strength of CTB under different mix proportion can be predicted quickly and accurately by using this model. PubDate: 2022-04-30
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Abstract: Abstract In order to design and manufacture a bionic bone scaffold for personalized bone tissue repairing, we give the performance requirements and indicators, and propose a method of establishing a three-dimensional bone scaffold solid model based on the Voronoi architecture. The modeling parameters, number of seed points and scaling factor are found, which can control the model performance. The finite element analysis model of bone scaffold with different number of seed points and scaling factor is set up. By adopting the method of theory analysis, experiment and simulation calculation, the performance parameters of the porosity, the specific surface area and the elastic modulus of 15 sets of bionic bone scaffold model are obtained. The relation between the bone scaffold model parameters and the porosity, the porosity and the specific surface area, the porosity and the equivalent elastic modulus are established. The individual design method of Voronoi bone scaffold is proposed. In the condition of given equivalent elastic modulus and the defected shape of bone, the bone scaffold model with spatial Voronoi architecture which accords with the performance requirements can be designed and produced rapidly, which provides reference for the personalized treatment of bone defecting. PubDate: 2022-04-30
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Abstract: Abstract The vehicles and pedestrians ranging is one of the basic functions of advanced driving assistance system. However, most of the ranging systems can only work on workstations with high computing power. To solve this problem, a lightweight algorithm is proposed to be packaged into Android application package, and be installed in Android smartphones for vehicles and pedestrians ranging. The proposed ranging system is based on the images obtained by smartphone’s monocular camera. To achieve real-time ranging, an 8-bit integer (int8) quantization algorithm is proposed to accelerate the inference of convolutional neural networks. To increase the detection precision, a zoom-in algorithm is further proposed to detect small targets in the distance. After having detected the 2D bounding boxes of vehicles and pedestrians, a pinhole ranging method is applied to estimate the distance. In order to verify the proposed algorithm, the mean average precision (mAP) and the frame per second (FPS) are first tested by using COCO dataset on Huawei P40Pro, then, the ranging precision on the real road. The experimental results show that this algorithm can successfully perform real-time ranging (15 FPS) with high precision (34.8 mAP) onto the tested smartphones. Finally, a possible mobile application based on the ranging algorithm, i.e., distance keeping warning, is also provided. PubDate: 2022-04-30
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