Research on double T-shape MEMS bionic vector hydrophone and its application in obstacle avoidance sonar

Sensor Review ◽  
2015 ◽  
Vol 35 (1) ◽  
pp. 76-84 ◽  
Author(s):  
Liu Linxian ◽  
Zhang Wendong ◽  
Zhang Guojun ◽  
Guan Linggang ◽  
Xue Chenyang ◽  
...  
Keyword(s):  
Obstacle Avoidance ◽  
Traffic Safety ◽  
Market Potential ◽  
Detection Sensitivity ◽  
Calibration Data ◽  
Underwater Acoustic ◽  
Content Type ◽  
Sonar System ◽  
Vector Hydrophone ◽  
Highly Effective

Purpose – The purpose of this paper is to develop a novel MEMS vector hydrophone with the key features of smaller size, better consistency, higher sensitivity and directional reception, and to develop a highly effective and economical obstacle avoidance sonar system. Currently, the typical vector hydrophones are resonant vector hydrophones based on the accelerometer, which greatly increases the volume and constrains the detection sensitivity. Also, because the system is composed of a number of devices, its size is difficult to be reduced. Design/methodology/approach – A novel double T-shape MEMS vector hydrophone is proposed with a fish’s lateral line organs as prototypes. The structure size and layout location of the piezoresistors were determined by simulation analysis, and the double T-shape microstructure was fabricated integrally by MEMS manufacturing technology, after which, the acoustic package of the microstructure was completed and the prototype was produced. Finally, the packaged hydrophone was calibrated in a standing wave field in the first-class national-defense underwater acoustic calibration station of China. Also, the design and test of an obstacle avoidance sonar system based on the vector hydrophone were completed. Findings – The calibration data show that the double T-shape vector hydrophone has a flat frequency response curve, exhibits a sensitivity of −180 dB (1 kHz, 0 dB reference 1 V/uPa) and shows a good directivity pattern in the form of an “8” shape. The test results of the obstacle avoidance sonar system further verify the feasibility of detecting underwater acoustic signals. Research limitations/implications – The next work is to increase the sensitivity by optimizing the microstructure and to realize orientation by organizing array. Practical implications – The hydrophone has the advantages of smaller size, lower cost and directional reception. It can be used to develop highly effective and economical obstacle avoidance sonar system, thus solving the problems of water transport efficiency and traffic safety. The hydrophone has broad application prospects and a huge market potential in the civilian fields. Originality/value – The MEMS technology and innovative bionic microstructure enable the miniaturization and low cost of the hydrophone. The hydrophone is easy to form array and can narrow the array aperture greatly. So, the hydrophone can be widely used in civil sonar systems.

A study on MEMS vector hydrophone and its orientation algorithm

Sensor Review ◽  
2020 ◽  
Vol 40 (2) ◽  
pp. 191-201
Author(s):  
Zhenzhen Shang ◽  
Wendong Zhang ◽  
Guojun Zhang ◽  
Xiaoyong Zhang ◽  
Lansheng Zhang ◽  
...  
Keyword(s):  
Standing Wave ◽  
Phase Error ◽  
Market Potential ◽  
Vibration Velocity ◽  
Wave Tube ◽  
Detection Mechanism ◽  
Content Type ◽  
Detection Systems ◽  
Vector Hydrophone ◽  
Standing Wave Tube

Purpose The problem of port and starboard ambiguity will exist when only utilize the vector or scalar parameters. Meanwhile, the amplitude-phase error between the vector and scalar can also cause this problem. In this paper, a compound MEMS vector hydrophone which contains cilia vector microstructure and piezoelectric ceramic tube has been presented to solve the problem. Compared with traditional MEMS vector hydrophone, the compound MEMS vector hydrophone can realize the measurement of sound pressure and vibration velocity simultaneously. Design/methodology/approach A compound MEMS vector hydrophone has been presented. The unipolar directivity of the combined signal which combine the acoustic pressure and vibration velocity is used to achieve the direction of arrival (DOA). This paper introduced the working principle and the target detection mechanism of the compound vector hydrophone. The amplitude and phase error are analyzed and corrected in the standing wave tube. After that, the authors use beam-forming algorithm to estimate the DOA. Findings The experimental results in the standing wave tube and the external field verified the vector hydrophone's directional accuracy up to 1 and 5 degrees, respectively. Practical implications The research of compound vector hydrophone plays an important role in marine acoustic exploration and engineering applications. Originality/value This research provides a basis for MEMS hydrophone directivity theory. The compound vector hydrophone has been applied in the underwater location, with a huge market potential in underwater detection systems.

scholarly journals Design and implementation of a jellyfish otolith-inspired MEMS vector hydrophone for low-frequency detection

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Renxin Wang ◽  
Wei Shen ◽  
Wenjun Zhang ◽  
Jinlong Song ◽  
Nansong Li ◽  
...  
Keyword(s):  
Structural Parameters ◽  
Low Frequency ◽  
Directivity Pattern ◽  
Stress Distributions ◽  
Strong Response ◽  
Underwater Acoustic ◽  
Frequency Detection ◽  
Vector Hydrophone ◽  
Shock Resistance ◽  
Marine Applications

AbstractDetecting low-frequency underwater acoustic signals can be a challenge for marine applications. Inspired by the notably strong response of the auditory organs of pectis jellyfish to ultralow frequencies, a kind of otolith-inspired vector hydrophone (OVH) is developed, enabled by hollow buoyant spheres atop cilia. Full parametric analysis is performed to optimize the cilium structure in order to balance the resonance frequency and sensitivity. After the structural parameters of the OVH are determined, the stress distributions of various vector hydrophones are simulated and analyzed. The shock resistance of the OVH is also investigated. Finally, the OVH is fabricated and calibrated. The receiving sensitivity of the OVH is measured to be as high as −202.1 dB@100 Hz (0 dB@1 V/μPa), and the average equivalent pressure sensitivity over the frequency range of interest of the OVH reaches −173.8 dB when the frequency ranges from 20 to 200 Hz. The 3 dB polar width of the directivity pattern for the OVH is measured as 87°. Moreover, the OVH is demonstrated to operate under 10 MPa hydrostatic pressure. These results show that the OVH is promising in low-frequency underwater acoustic detection.

scholarly journals Rough diamonds in emerging markets: legacy, competitiveness, and sustained high performance

2019 ◽  
Vol 26 (3) ◽  
pp. 363-386
Author(s):  
Seung Ho Park ◽  
Gerardo R. Ungson
Keyword(s):  
Human Capital ◽  
Emerging Markets ◽  
High Performance ◽  
Core Competencies ◽  
Market Potential ◽  
Government Support ◽  
Screening Tests ◽  
Institutional Voids ◽  
Content Type ◽  
Over Time

Purpose The purpose of this paper is to uncover the underlying drivers of sustained high performing companies based on a field study of 127 companies in Brazilian, Russian, Indian and Chinese (BRIC) and Association of Southeast Asian Nations (ASEAN) emerging markets. Understanding these companies provides a complementary way of appraising the growth, development and transformation of emerging markets. The authors synthesize the findings in an overarching framework that covers six strategies for building and sustaining legacy that leads to the succession of intergenerational wealth over time: overcoming institutional voids, inclusive markets, deepening localization, nurturing government support, building core competencies and harnessing human capital. The authors relate these strategies to different levels of development using Prahalad and Hart’s BOP framework. Design/methodology/approach This study examines the underlying drivers of sustained high-performance companies based on field studies from an initial set of 105,260 BRIC companies and close to 500 companies in ASEAN. The methods employed four screening tests to arrive at a selection of the highest-performing firms: 70 firms in the BRIC nations and 58 firms from ASEAN. Following the selection, the authors constructed cases using primary interviews and secondary data, with the assistance of Ernst & Young and with academic colleagues in Manila. These studies were originally conducted in two separate time periods and reported accordingly. This paper synthesizes the findings of these two studies to arrive at an extended integrative framework. Findings From the cases, the authors examine six strategies for building and sustaining legacy that lead to high performance over time: overcoming institutional voids, creating inclusive markets, deepening localization, nurturing government support, building core competencies and harnessing human capital. To address the evolving state of institutional voids in these countries, the authors employ similar methods to hypothesize the placement of these strategies in the context of the world economic pyramid, initially formulated as the “bottom of the pyramid” framework. Originality/value This paper synthesizes and extends the authors’ previous works by proposing the concept of legacy to describe the emergence and succession of local exemplary firms in emerging markets. This study aims to complement extant measures of nation-growth based primarily on GDP. The paper also extends the literature on institutional voids in shifting the focus from the mix of voids to their evolving state. Altogether, the paper provides a complementary narrative on assessing the market potential of emerging markets by adopting several categories of performance.

Robot obstacle avoidance system using deep reinforcement learning

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Xiaojun Zhu ◽  
Yinghao Liang ◽  
Hanxu Sun ◽  
Xueqian Wang ◽  
Bin Ren
Keyword(s):  
Reinforcement Learning ◽  
Collision Avoidance ◽  
Obstacle Avoidance ◽  
Learning Algorithm ◽  
Optimal Path ◽  
Environmental Parameters ◽  
Working Environment ◽  
Content Type ◽  
Practical Applications ◽  
Human Operators

Purpose Most manufacturing plants choose the easy way of completely separating human operators from robots to prevent accidents, but as a result, it dramatically affects the overall quality and speed that is expected from human–robot collaboration. It is not an easy task to ensure human safety when he/she has entered a robot’s workspace, and the unstructured nature of those working environments makes it even harder. The purpose of this paper is to propose a real-time robot collision avoidance method to alleviate this problem. Design/methodology/approach In this paper, a model is trained to learn the direct control commands from the raw depth images through self-supervised reinforcement learning algorithm. To reduce the effect of sample inefficiency and safety during initial training, a virtual reality platform is used to simulate a natural working environment and generate obstacle avoidance data for training. To ensure a smooth transfer to a real robot, the automatic domain randomization technique is used to generate randomly distributed environmental parameters through the obstacle avoidance simulation of virtual robots in the virtual environment, contributing to better performance in the natural environment. Findings The method has been tested in both simulations with a real UR3 robot for several practical applications. The results of this paper indicate that the proposed approach can effectively make the robot safety-aware and learn how to divert its trajectory to avoid accidents with humans within the workspace. Research limitations/implications The method has been tested in both simulations with a real UR3 robot in several practical applications. The results indicate that the proposed approach can effectively make the robot be aware of safety and learn how to change its trajectory to avoid accidents with persons within the workspace. Originality/value This paper provides a novel collision avoidance framework that allows robots to work alongside human operators in unstructured and complex environments. The method uses end-to-end policy training to directly extract the optimal path from the visual inputs for the scene.

“I don’t feel any danger because I am in my own community”: a photovoice study on adolescents’ perceived community safety

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yingwei Yang ◽  
Karen Liller ◽  
Dinorah Martinez Tyson ◽  
Martha Coulter
Keyword(s):  
Protective Factors ◽  
Traffic Safety ◽  
Rural Areas ◽  
Training Session ◽  
Well Being ◽  
Influential Factors ◽  
Community Safety ◽  
Content Type ◽  
Safety Promotion ◽  
Photovoice Methodology

Purpose A safe environment is critical for adolescents’ well-being. The purpose of this photovoice study is to explore reasons that make adolescents feel safe in their community. Design/methodology/approach This study was conducted in Florida through both online and in-person recruitment. After a training session on the ethical and technical use of cameras and a brief introduction of the photovoice methodology, six adolescents took photos (n = 66) in their community and discussed their photos guided by the revised SHOWeD framework. Abridged transcripts were used to match photos with corresponding discussions. Thematic analysis was conducted by the research team. Findings This study identified four main themes related to adolescents’ safe perceptions, including community protective factors (n = 22 photos) such as safe physical environments and community cohesion; family protective factors (n = 14 photos) including safe home and caring parents; traffic safety (n = 14 photos), such as proper road signs, seat belts for car safety and helmets and locks for bicycle safety; and public safety (n = 8 photos), such as emergency numbers, fire departments and police cars and officers. Research limitations/implications Due to the limited number of participants, this study did not compare the similarities and differences of safety perceptions between adolescents living in high crime areas (urban communities) and those in low crime areas (suburban and rural communities). Future photovoice studies are recommended to further explore the influential factors associated with adolescents’ perceived community safety in urban and rural areas with different levels of crime rates to provide more evidence on targeted strategies for community safety promotion in each area. Practical implications By exploring the reasons for adolescents’ safe feelings in their community using photovoice, this study provides insights for future intervention programs to promote community safety for children and adolescents from the community, family, traffic and societal perspectives. Social implications This photovoice study not only empowers adolescents to identify community assets related to their safe perceptions but also illustrates valuable insights for researchers and public health professionals for safety promotion. Originality/value This study has used a broad research question to explore the reasons that make adolescents feel safe, providing them the opportunities to express their opinions by photo taking and photo discussions. Moreover, rich information at the community, family and societal levels has been collected as related to factors contributing to adolescents’ safe perceptions, adding to the literature on community safety. In addition, this photovoice study has offered both in-person and online participation. Such combination not only provides adolescents with an opportunity to choose a participation method that works best for them but also adds to the photovoice methodology by extending the data collection from in-person to online.

Real-time velocity scaling and obstacle avoidance for industrial robots using fuzzy dynamic movement primitives and virtual impedances

2018 ◽  
Vol 45 (1) ◽  
pp. 110-126 ◽  
Author(s):  
Iman Kardan ◽  
Alireza Akbarzadeh ◽  
Ali Mousavi Mohammadi
Keyword(s):  
Real Time ◽  
Obstacle Avoidance ◽  
Time Constant ◽  
Fuzzy System ◽  
Industrial Robots ◽  
Simple Method ◽  
Content Type ◽  
Dynamic Movement ◽  
Steering Mechanism ◽  
Novel Method

Purpose This paper aims to increase the safety of the robots’ operation by developing a novel method for real-time implementation of velocity scaling and obstacle avoidance as the two widely accepted safety increasing concepts. Design/methodology/approach A fuzzy version of dynamic movement primitive (DMP) framework is proposed as a real-time trajectory generator with imbedded velocity scaling capability. Time constant of the DMP system is determined by a fuzzy system which makes decisions based on the distance from obstacle to the robot’s workspace and its velocity projection toward the workspace. Moreover, a combination of the DMP framework with a human-like steering mechanism and a novel configuration of virtual impedances is proposed for real-time obstacle avoidance. Findings The results confirm the effectiveness of the proposed method in real-time implementation of the velocity scaling and obstacle avoidance concepts in different cases of single and multiple stationary obstacles as well as moving obstacles. Practical implications As the provided experiments indicate, the proposed method can effectively increase the real-time safety of the robots’ operations. This is achieved by developing a simple method with low computational loads. Originality/value This paper proposes a novel method for real-time implementation of velocity scaling and obstacle avoidance concepts. This method eliminates the need for modification of original DMP formulation. The velocity scaling concept is implemented by using a fuzzy system to adjust the DMP’s time constant. Furthermore, the novel impedance configuration makes it possible to obtain a non-oscillatory convergence to the desired path, in all degrees of freedom.

scholarly journals A New Highly Sensitive and Specific Real-Time PCR Assay Targeting the Malate Dehydrogenase Gene ofKingella kingaeand Application to 201 Pediatric Clinical Specimens

2018 ◽  
Vol 56 (8) ◽  
Author(s):  
Nawal El Houmami ◽  
Guillaume André Durand ◽  
Janek Bzdrenga ◽  
Anne Darmon ◽  
Philippe Minodier ◽  
...  
Keyword(s):  
Real Time ◽  
Malate Dehydrogenase ◽  
Real Time Pcr ◽  
Detection Sensitivity ◽  
Rt Pcr ◽  
Pcr Assay ◽  
Content Type ◽  
Clinical Specimens ◽  
Specificity And Sensitivity ◽  
Pcr Assays

ABSTRACTKingella kingaeis a significant pediatric pathogen responsible for bone and joint infections, occult bacteremia, and endocarditis in early childhood. Past efforts to detect this bacterium using culture and broad-range 16S rRNA gene PCR assays from clinical specimens have proven unsatisfactory; therefore, by the late 2000s, these were gradually phased out to explore the benefits of specific real-time PCR tests targeting thegroELgene and the RTX locus ofK. kingae. However, recent studies showed that real-time PCR (RT-PCR) assays targeting theKingellasp. RTX locus that are currently available for the diagnosis ofK. kingaeinfection lack specificity because they could not distinguish betweenK. kingaeand the recently describedKingella negevensisspecies. Furthermore,in silicoanalysis of thegroELgene from a large collection of 45K. kingaestrains showed that primers and probes fromK. kingaegroEL-based RT-PCR assays display a few mismatches withK. kingae groELvariations that may result in decreased detection sensitivity, especially in paucibacillary clinical specimens. In order to provide an alternative togroEL- and RTX-targeting RT-PCR assays that may suffer from suboptimal specificity and sensitivity, aK. kingae-specific RT-PCR assay targeting the malate dehydrogenase (mdh) gene was developed for predicting no mismatch between primers and probe and 18 variants of theK. kingae mdhgene from 20 distinct sequence types ofK. kingae. This novelK. kingae-specific RT-PCR assay demonstrated high specificity and sensitivity and was successfully used to diagnoseK. kingaeinfections and carriage in 104 clinical specimens from children between 7 months and 7 years old.

Design, development and performance evaluation of pressure sensor using eddy current displacement sensing coil

Sensor Review ◽  
2018 ◽  
Vol 38 (2) ◽  
pp. 248-258
Author(s):  
Gobi K. ◽  
Kannapiran B. ◽  
Devaraj D. ◽  
Valarmathi K.
Keyword(s):  
Performance Evaluation ◽  
Eddy Current ◽  
Pressure Sensor ◽  
Strain Gauge ◽  
Pressure Sensors ◽  
Calibration Data ◽  
Position Measurement ◽  
Content Type ◽  
Short Period ◽  
Type Pressure

Purpose The conventional strain gauge type pressure sensor suffers in static testing of engines due to the contact transduction method. This paper aims to focus on the concept of non-contact transduction-based pressure sensor using eddy current displacement sensing coil (ECDS) to overcome the temperature limitations of the strain gauge type pressure sensor. This paper includes the fabrication of prototypes of the proposed pressure sensor and its performance evaluation by static calibration. The fabricated pressure sensor is proposed to measure pressure in static test environment for a short period in the order of few seconds. The limitations of the fabricated pressure sensor related to temperature problems are highlighted and the suitable design changes are recommended to aid the future design. Design/methodology/approach The design of ECDS-based pressure sensor is aimed to provide non-contact transduction to overcome the limitations of the strain gauge type of pressure sensor. The ECDS is designed and fabricated with two configurations to measure deflection of the diaphragm corresponding to the applied pressure. The fabricated ECDS is calibrated using a standard micro meter to ensure transduction within limits. The fabricated prototypes of pressure sensors are calibrated using dead weight tester, and the calibration results are analyzed to select the best configuration. The proposed pressure sensor is tested at different temperatures, and the test results are analyzed to provide recommendations to overcome the shortcomings. Findings The performance of the different configurations of the pressure sensor using ECDS is evaluated using the calibration data. The analysis of the calibration results indicates that the pressure sensor using ECDS (coil-B) with the diaphragm as target is the best configuration. The accuracy of the fabricated pressure sensor with best configuration is ±2.8 per cent and the full scale (FS) output is 3.8 KHz. The designed non-contact transduction method extends the operating temperature of the pressure sensor up to 150°C with the specified accuracy for the short period. Originality/value Most studies of eddy current sensing coil focus on the displacement and position measurement but not on the pressure measurement. This paper is concerned with the design of the pressure sensor using ECDS to realize the non-contact transduction to overcome the limitations of strain gauge type pressure sensors and evaluation of the fabricated prototypes. It is shown that the accuracy of the proposed pressure sensor is not affected by the high temperature for the short period due to non-contact transduction using ECDS.

Aspiration, foreignness liability and market potential

2018 ◽  
Vol 35 (6) ◽  
pp. 1009-1032
Author(s):  
Lee Li ◽  
Gongming Qian ◽  
Zhengming Qian ◽  
Irene R.R. Lu
Keyword(s):  
Performance Feedback ◽  
Small Firms ◽  
Theory Of The Firm ◽  
Market Potential ◽  
Content Type ◽  
Country Market ◽  
International Behavior ◽  
Relationship Of ◽  
The Impact ◽  
The Relationship

PurposeUsing behavioral theory of the firm, the purpose of this paper is to examine how a small firm’s performance relative to historical and social aspirations is related to its international entrepreneurial orientation (IEO). This study also explores two environmental factors, liability of foreignness (LoF) and host-country market potential (HMP), as the moderators for the relationship of performance and IEO.Design/methodology/approachThis study uses survey for data collection from Canadian small firms and employs regression models for data analysis.FindingsThe results show that small firms demonstrate stronger IEO when their performance is below aspirations, but their IEO diminishes when their performance exceeds aspirations. The authors also found that a small firm’s LoF does not moderate the impact of its performance feedback on IEO. However, the authors found HMP plays a moderating role when a small firm’s performance is below aspirations.Originality/valueThis study investigates the relationship of IEO to aspiration and found that this relationship is moderated by HMP. The study advances our knowledge on small firms’ international behavior.

Mechanical arm obstacle avoidance path planning based on improved artificial potential field method

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Tianying Xu ◽  
Haibo Zhou ◽  
Shuaixia Tan ◽  
Zhiqiang Li ◽  
Xia Ju ◽  
...  
Keyword(s):  
Path Planning ◽  
Obstacle Avoidance ◽  
Potential Field ◽  
Planning Process ◽  
Field Method ◽  
Artificial Potential Field ◽  
Local Minima ◽  
Content Type ◽  
Potential Field Method ◽  
Artificial Potential Field Method

Purpose This paper aims to resolve issues of the traditional artificial potential field method, such as falling into local minima, low success rate and lack of ability to sense the obstacle shapes in the planning process. Design/methodology/approach In this paper, an improved artificial potential field method is proposed, where the object can leave the local minima point, where the algorithm falls into, while it avoids the obstacle, following a shorter feasible path along the repulsive equipotential surface, which is locally optimized. The whole obstacle avoidance process is based on the improved artificial potential field method, applied during the mechanical arm path planning action, along the motion from the starting point to the target point. Findings Simulation results show that the algorithm in this paper can effectively perceive the obstacle shape in all the selected cases and can effectively shorten the distance of the planned path by 13%–41% with significantly higher planning efficiency compared with the improved artificial potential field method based on rapidly-exploring random tree. The experimental results show that the improved artificial potential field method can effectively plan a smooth collision-free path for the object, based on an algorithm with good environmental adaptability. Originality/value An improved artificial potential field method is proposed for optimized obstacle avoidance path planning of a mechanical arm in three-dimensional space. This new approach aims to resolve issues of the traditional artificial potential field method, such as falling into local minima, low success rate and lack of ability to sense the obstacle shapes in the planning process.

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