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Agnieszka Szczęsna, Przemysław Pruszowski
Inertial orientation tracking is still an area of active research, especially in the context of out-door, real-time, human motion capture. Existing systems either propose loosely coupled tracking approaches where each segment is considered independently, taking the resulting drawbacks into account, or tightly coupled solutions that are limited to a fixed chain with few segments. Such solutions have no flexibility to change the skeleton structure, are dedicated to a specific set of joints, and have high computational complexity...
2016: SpringerPlus
Gang Tang, Bin Yang, Cheng Hou, Guimiao Li, Jingquan Liu, Xiang Chen, Chunsheng Yang
Recently, piezoelectric energy harvesters (PEHs) have been paid a lot of attention by many researchers to convert mechanical energy into electrical and low level vibration. Currently, most of PEHs worked under high frequency and low level vibration. In this paper, we propose a micro cantilever generator based on the bonding of bulk PZT wafer and phosphor bronze, which is fabricated by MEMS technology, such as mechanical chemical thinning and etching. The experimental results show that the open-circuit output voltage, output power and power density of this fabricated prototype are 35 V, 321 μW and 8664 μW cm(-3) at the resonant frequency of 100...
December 8, 2016: Scientific Reports
Fabian Marcel Rast, Judith Verena Graser, André Meichtry, Markus Josef Ernst, Christoph Michael Bauer
Postural control strategies can be investigated by kinematic analysis of joint movements. However, current research is focussing mainly on the analysis of centre of pressure excursion and lacks consensus on how to assess joint movement during postural control tasks. This study introduces a new signal processing technique to comprehensively quantify joint sway during standing and evaluates its reproducibility. Fifteen patients with non-specific low back pain and ten asymptomatic participants performed three repetitions of a 60-second standing task on foam surface...
November 29, 2016: Journal of Biomechanics
Massimiliano Pau, Silvia Caggiari, Alessandro Mura, Federica Corona, Bruno Leban, Giancarlo Coghe, Lorena Lorefice, Maria Giovanna Marrosu, Eleonora Cocco
BACKGROUND: This study aims to verify the feasibility of use of wearable accelerometers in an ambulatory environment to assess spatiotemporal parameters of gait in people with Multiple Sclerosis (pwMS), as well as the correlation of objective data with patient-reported outcomes. METHODS: One hundred and five pwMS (Expanded Disability Status Scale, EDSS in the range 0-6.5) classified in three sub-groups (EDSS 0-1.5, EDSS 2-4, EDSS 4.5-6.5) and 47 healthy controls (HC) participated in the study...
November 2016: Multiple Sclerosis and related Disorders
Melissa M B Morrow, Bethany Lowndes, Emma Fortune, Kenton R Kaufman, Susan Hallbeck
The purpose of this study was to validate a commercially available IMU system against a standard lab-based motion capture system for the measurement of shoulder elevation, elbow flexion, trunk flexion/extension and neck flexion/extension kinematics. The validation analyses were applied to six surgical faculty members performing a standard, simulated surgical training task that mimics minimally invasive surgery. Three-dimensional joint kinematics were simultaneously recorded by an optical motion capture system and an IMU system with six sensors placed on the head, chest, and bilateral upper and lower arms...
December 5, 2016: Journal of Applied Biomechanics
Rahel Ammann, Wolfgang Taube, Thomas Wyss
PURPOSE: The aim of the present study was to quantify gait asymmetry in well-trained runners, with and without previous injuries during interval training sessions incorporating different distances. METHODS: Twelve well-trained runners participated in eight high-intensity interval training sessions on a synthetic track over a 4-week period. The training consisted of 10 × 400 m, 8 × 600 m, 7 × 800 m, and 6 × 1000 m running. Using an inertial measurement unit, the ground contact time (GCT) of every step was recorded...
December 5, 2016: International Journal of Sports Physiology and Performance
Shu-Yin Chiang, Yao-Chiang Kan, Yun-Shan Chen, Ying-Ching Tu, Hsueh-Chun Lin
Ubiquitous health care (UHC) is beneficial for patients to ensure they complete therapeutic exercises by self-management at home. We designed a fuzzy computing model that enables recognizing assigned movements in UHC with privacy. The movements are measured by the self-developed body motion sensor, which combines both accelerometer and gyroscope chips to make an inertial sensing node compliant with a wireless sensor network (WSN). The fuzzy logic process was studied to calculate the sensor signals that would entail necessary features of static postures and dynamic motions...
December 3, 2016: Sensors
Yi Lu, Dongyan Wei, Qifeng Lai, Wen Li, Hong Yuan
Indoor positioning has recently become an important field of interest because global navigation satellite systems (GNSS) are usually unavailable in indoor environments. Pedestrian dead reckoning (PDR) is a promising localization technique for indoor environments since it can be implemented on widely used smartphones equipped with low cost inertial sensors. However, the PDR localization severely suffers from the accumulation of positioning errors, and other external calibration sources should be used. In this paper, a context-recognition-aided PDR localization model is proposed to calibrate PDR...
November 30, 2016: Sensors
Xiao Zhou, Gongliu Yang, Qingzhong Cai, Jing Wang
In recent years, with the emergency of high precision inertial sensors (accelerometers and gyros), gravity compensation has become a major source influencing the navigation accuracy in inertial navigation systems (INS), especially for high-precision INS. This paper presents preliminary results concerning the effect of gravity disturbance on INS. Meanwhile, this paper proposes a novel gravity compensation method for high-precision INS, which estimates the gravity disturbance on the track using the extreme learning machine (ELM) method based on measured gravity data on the geoid and processes the gravity disturbance to the height where INS has an upward continuation, then compensates the obtained gravity disturbance into the error equations of INS to restrain the INS error propagation...
November 29, 2016: Sensors
Jiateng Hou, Yingfei Sun, Lixin Sun, Bingyu Pan, Zhipei Huang, Jiankang Wu, Zhiqiang Zhang
This paper proposes a neuromusculoskeletal (NMS) model to predict individual muscle force during elbow flexion and extension. Four male subjects were asked to do voluntary elbow flexion and extension. An inertial sensor and surface electromyography (sEMG) sensors were attached to subject's forearm. Joint angle calculated by fusion of acceleration and angular rate using an extended Kalman filter (EKF) and muscle activations obtained from the sEMG signals were taken as the inputs of the proposed NMS model to determine individual muscle force...
November 29, 2016: Sensors
Shuang Du, Wei Sun, Yang Gao
Micro-electro-mechanical-systems (MEMS) inertial measurement unit (IMU) outputs are corrupted by significant sensor errors. The navigation errors of a MEMS-based inertial navigation system will therefore accumulate very quickly over time. This requires aiding from other sensors such as Global Navigation Satellite Systems (GNSS). However, it will still remain a significant challenge in the presence of GNSS outages, which are typically in urban canopies. This paper proposed a rotary inertial navigation system (INS) to mitigate navigation errors caused by MEMS inertial sensor errors when external aiding information is not available...
November 29, 2016: Sensors
Bhargava Teja Nukala, Taro Nakano, Amanda Rodriguez, Jerry Tsay, Jerry Lopez, Tam Q Nguyen, Steven Zupancic, Donald Y C Lie
Gait analysis using wearable wireless sensors can be an economical, convenient and effective way to provide diagnostic and clinical information for various health-related issues. In this work, our custom designed low-cost wireless gait analysis sensor that contains a basic inertial measurement unit (IMU) was used to collect the gait data for four patients diagnosed with balance disorders and additionally three normal subjects, each performing the Dynamic Gait Index (DGI) tests while wearing the custom wireless gait analysis sensor (WGAS)...
November 29, 2016: Biosensors
Weisheng Kong, Salvatore Sessa, Massimiliano Zecca, Atsuo Takanishi
The inertial measurement unit is popularly used as a wearable and flexible tool for human motion tracking. Sensor-to-body alignment, or anatomical calibration (AC), is fundamental to improve accuracy and reliability. Current AC methods either require extra movements or are limited to specific joints. In this research, the authors propose a novel method to achieve AC from standard motion tests (such as walking, or sit-to-stand), and compare the results with the AC obtained from specially designed movements. The proposed method uses the limited acceleration range on medial-lateral direction, and applies principal component analysis to estimate the sagittal plane, while the vertical direction is estimated from acceleration during quiet stance...
November 28, 2016: Sensors
Yeoun Jae Kim, Jong Hyun Seo, Hong Rae Kim, Kwang Gi Kim
BACKGROUND: Many robotic needle-biopsy systems have been developed to enhance the accuracy of needle-biopsy intervention. These systems can reduce the intervention time and the radiation exposure of clinicians. However, respiratory-motion compensation is needed to ensure the accuracy and efficiency of needle biopsy intervention. METHODS: Human respiratory-motion data were acquired using three inertial measurement units (IMUs), and respiratory motion was simulated using the Stewart-Gough platform...
December 4, 2016: International Journal of Medical Robotics + Computer Assisted Surgery: MRCAS
A K Davis, D T Michel, R S Craxton, R Epstein, M Hohenberger, T Mo, D H Froula
As hydrodynamics codes develop to increase understanding of three-dimensional (3-D) effects in inertial confinement fusion implosions, diagnostics must adapt to evaluate their predictive accuracy. A 3-D radiation postprocessor was developed to investigate the use of soft x-ray self-emission images of an imploding target to measure the size of nonuniformities on the target surface. Synthetic self-emission images calculated from 3-D simulations showed a narrow ring of emission outside the ablation surface of the target...
November 2016: Review of Scientific Instruments
P S Datte, J S Ross, D H Froula, K D Daub, J Galbraith, S Glenzer, B Hatch, J Katz, J Kilkenny, O Landen, D Manha, A M Manuel, W Molander, D Montgomery, J Moody, G F Swadling, J Weaver
The National Ignition Facility (NIF) is a 192 laser beam facility designed to support the Stockpile Stewardship, High Energy Density and Inertial Confinement Fusion (ICF) programs. We report on the design of an Optical Thomson Scattering (OTS) diagnostic that has the potential to transform the community's understanding of NIF hohlraum physics by providing first principle, local, time-resolved measurements of under-dense plasma conditions. The system design allows operation with different probe laser wavelengths by manual selection of the appropriate beam splitter and gratings before the shot...
November 2016: Review of Scientific Instruments
J S Milnes, T M Conneely, C J Horsfield
Photek are a well-established supplier of microchannel plate (MCP) photomultiplier tubes (PMTs) to the inertial confinement fusion community. The analogue signals produced at the major inertial confinement fusion facilities cover many orders of magnitude, therefore understanding the upper saturation limit of MCP-PMTs to large low rate signals takes on a high importance. Here we present a study of a single and a double MCP-PMT with 10 mm diameter active area. The saturation was studied for a range of optical pulse widths from 4 ns to 100 ns and at a range of electron gain values: 10(3) to 10(4) for the single and 10(4) to 10(6) for the double...
November 2016: Review of Scientific Instruments
G D Sutcliffe, L M Milanese, D Orozco, B Lahmann, M Gatu Johnson, F H Séguin, H Sio, J A Frenje, C K Li, R D Petrasso, H-S Park, J R Rygg, D T Casey, R Bionta, D P Turnbull, C M Huntington, J S Ross, A B Zylstra, M J Rosenberg, V Yu Glebov
CR-39 detectors are used routinely in inertial confinement fusion (ICF) experiments as a part of nuclear diagnostics. CR-39 is filtered to stop fast ablator ions which have been accelerated from an ICF implosion due to electric fields caused by laser-plasma interactions. In some experiments, the filtering is insufficient to block these ions and the fusion-product signal tracks are lost in the large background of accelerated ion tracks. A technique for recovering signal in these scenarios has been developed, tested, and implemented successfully...
November 2016: Review of Scientific Instruments
G A Wurden, L A Stephey, C Biedermann, M W Jakubowski, J P Dunn, M Gamradt
A high-resolution imaging system, consisting of megapixel mid-IR and visible cameras along the same line of sight, has been prepared for the new W7-X stellarator and was operated during Operational Period 1.1 to view one of the five inboard graphite limiters. The radial line of sight, through a large diameter (184 mm clear aperture) uncoated sapphire window, couples a direct viewing 1344 × 784 pixel FLIR SC8303HD camera. A germanium beam-splitter sends visible light to a 1024 × 1024 pixel Allied Vision Technologies Prosilica GX1050 color camera...
November 2016: Review of Scientific Instruments
L C Jarrott, L R Benedetti, H Chen, N Izumi, S F Khan, T Ma, S R Nagel, O L Landen, A Pak, P K Patel, M Schneider, H A Scott
We report on measurements of the electron temperature in the hotspot of inertially confined, layered, spherical implosions on the National Ignition Facility using a differential filtering diagnostic. Measurements of the DT and DD ion temperatures using neutron time-of-flight detectors are complicated by the contribution of hot spot motion to the peak width, which produce an apparent temperature higher than the thermal temperature. The electron temperature is not sensitive to this non-thermal velocity and is thus a valuable input to interpreting the stagnated hot spot conditions...
November 2016: Review of Scientific Instruments
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