A Soft 3-dimensional Force Sensor For Measuring Head Impacts In Football Helmets

Purpose Many manufacturing sites require precision assembly. Particularly, similar to cell phones, assembly at the sub-mm scale is not easy, even for humans. In addition, the system should assemble each part with adequate force and avoid breaking the circuits with excessive force. The purpose of this study is to assemble high precision components with relatively reasonable vision devices compared to previous studies. Design/methodology/approach This paper presents a vision-force guided precise assembly system using a force sensor and two charge coupled device (CCD) cameras without an expensive 3-dimensional (3D) sensor or computer-aided design model. The system accurately estimates 6 degrees-of-freedom (DOF) poses from a 2D image in real time and assembles parts with the proper force. Findings In this experiment, three connectors are assembled on a printed circuit board. This system obtains high accuracy under 1 mm and 1 degree error, which shows that this system is effective. Originality/value This is a new method for sub-mm assembly using only two CCD cameras and one force sensor.

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Emergent Access to the Airway and Chest in American Football Players

Journal of Athletic Training ◽

10.4085/1062-6050-50.4.04 ◽

2015 ◽

Vol 50 (7) ◽

pp. 681-687 ◽

Cited By ~ 6

Author(s):

Erik E. Swartz ◽

Jason P. Mihalik ◽

Laura C. Decoster ◽

Sossan Al-Darraji ◽

Justin Bric

Keyword(s):

Life Support ◽

Athletic Trainers ◽

Random Order ◽

Medical Personnel ◽

Face Mask ◽

American Football ◽

Football Players ◽

3 Dimensional ◽

Football Helmets ◽

Quasi Experimental

Context American football has the highest rate of fatalities and catastrophic injuries of any US sport. The equipment designed to protect athletes from these catastrophic events challenges the ability of medical personnel to obtain neutral spine alignment and immobilization during airway and chest access for emergency life-support delivery. Objective To compare motion, time, and difficulty during removal of American football helmets, face masks, and shoulder pads. Design Quasi-experimental, crossover study. Setting Controlled laboratory. Patients or Other Participants We recruited 40 athletic trainers (21 men, 19 women; age = 33.7 ± 11.2 years, height = 173.1 ± 9.2 cm, mass = 80.7 ± 17.1 kg, experience = 10.6 ± 10.4 years). Intervention(s) Paired participants conducted 16 trials in random order for each of 4 helmet, face-mask, and shoulder-pad combinations. An 8-camera, 3-dimensional motion-capture system was used to record head motion in live models wearing properly fitted helmets and shoulder pads. Main Outcome Measure(s) Time and perceived difficulty (modified Borg CR-10). Results Helmet removal resulted in greater motion than face-mask removal, respectively, in the sagittal (14.88°, 95% confidence interval [CI] = 13.72°, 16.04° versus 7.04°, 95% CI = 6.20°, 7.88°; F1,19 = 187.27, P < .001), frontal (7.00°, 95% CI = 6.47°, 7.53° versus 4.73°, 95% CI = 4.20°, 5.27°; F1,19 = 65.34, P < .001), and transverse (7.00°, 95% CI = 6.49°, 7.50° versus 4.49°, 95% CI = 4.07°, 4.90°; F1,19 = 68.36, P < .001) planes. Face-mask removal from Riddell 360 helmets took longer (31.22 seconds, 95% CI = 27.52, 34.91 seconds) than from Schutt ION 4D helmets (20.45 seconds, 95% CI = 18.77, 22.12 seconds) or complete ION 4D helmet removal (26.40 seconds, 95% CI = 23.46, 29.35 seconds). Athletic trainers required less time to remove the Riddell Power with RipKord (21.96 seconds, 95% CI = 20.61°, 23.31° seconds) than traditional shoulder pads (29.22 seconds, 95% CI = 27.27, 31.17 seconds; t19 = 9.80, P < .001). Conclusions Protective equipment worn by American football players must eventually be removed for imaging and medical treatment. Our results fill a gap in the evidence to support current recommendations for prehospital emergent management in patients wearing protective football equipment. Helmet face masks and shoulder pads with quick-release designs allow for clinically acceptable removal times without inducing additional motion or difficulty.

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Measuring head impacts: accelerometers and other sensors

Sports Neurology - Handbook of Clinical Neurology ◽

10.1016/b978-0-444-63954-7.00023-9 ◽

2018 ◽

pp. 235-243 ◽

Cited By ~ 3

Author(s):

Bethany Rowson ◽

Abigail Tyson ◽

Steven Rowson ◽

Stefan Duma

Keyword(s):

Measuring Head ◽

Head Impacts

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Multiple Wafer Bonding for MEMS Applications

MRS Proceedings ◽

10.1557/proc-681-i7.2 ◽

2001 ◽

Vol 681 ◽

Author(s):

M. Reiche ◽

M. Haueis ◽

J. Dual ◽

C. Cavalloni ◽

R. Buser

Keyword(s):

Wafer Bonding ◽

Microelectromechanical Systems ◽

Single Crystal Silicon ◽

Force Sensor ◽

Semiconductor Wafer ◽

Crystal Silicon ◽

Static Loads ◽

3 Dimensional ◽

Wafer Direct Bonding ◽

Better Than

ABSTRACTMost of the microelectromechanical systems (MEMS) require a 3-dimensional architecture which can efficiently be realized by multiple semiconductor wafer direct bonding. The present paper demonstrates the method on a force sensor for high resolution measurements of static loads. To minimize temperature stress an all-in silicon solution was developed in contrast to micromachined resonant force sensors published already in the literature.The presented force sensor integrates load coupling, the excitation and detection of the vibration of the microresonator in one and the same single crystal silicon package. First measurements proved a sensitivity of 26 Hz/N and a resolution better than 3 mN.

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Analysis of HIC and Hydrostatic Pressure in the Human Head during NOCSAE Tests of American Football Helmets

Brain Sciences ◽

10.3390/brainsci11030287 ◽

2021 ◽

Vol 11 (3) ◽

pp. 287

Author(s):

Mateusz Dymek ◽

Mariusz Ptak ◽

Monika Ratajczak ◽

Fábio A. O. Fernandes ◽

Artur Kwiatkowski ◽

...

Keyword(s):

Human Head ◽

Numerical Approach ◽

American Football ◽

Head Model ◽

Head Impacts ◽

Social Burden ◽

Direct Head ◽

Hybrid Iii ◽

Football Helmets ◽

Head Injury Criteria

Brain damage is a serious economic and social burden. Contact sports such as American football, are one of the most common sources of concussions. The biomechanical response of the head–helmet system caused by dynamic loading plays a major role. The literature has focused on measuring the resultant kinematics that act on the head and helmet during tackles. However, few studies have focused on helmet validation tests, supported by recent findings and emerging numerical approaches. The future of helmet standards could benefit from insights at the level of injury mechanisms, using numerical tools to assess the helmets. Therefore, in this work, a numerical approach is employed to investigate the influence of intracranial pressure (ICP) on brain pathophysiology during and after helmeted impacts, which are common in American football. The helmeted impacts were performed at several impact locations according to the NOCSAE standard (configurations A, AP, B, C, D, F, R, UT). In order to evaluate the ICP levels, the αHEAD finite element head and brain model was combined with a Hybrid III-neck structure and then coupled with an American football helmet to simulate the NOCSAE impacts. In addition, the ICP level was analyzed together with the resulting HIC value, since the latter is commonly used, in this application and others, as the injury criterion. The obtained results indicate that ICP values exceed the common threshold of head injury criteria and do not correlate with HIC values. Thus, this work raises concern about applying the HIC to predict brain injury in American football direct head impacts, since it does not correlate with ICP predicted with the FE head model.

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Application of Digital Volume Correlation Algorithm to Cell Mechanics

Volume 11: Mechanics of Solids, Structures and Fluids ◽

10.1115/imece2009-13253 ◽

2009 ◽

Author(s):

Hyock J. Kwon ◽

Boxin Zhao ◽

Praveen N. P. Rao

Keyword(s):

Cell Mechanics ◽

Cross Correlation ◽

Speckle Pattern ◽

Traction Force ◽

Force Sensor ◽

Digital Volume Correlation ◽

Linear Elasticity Theory ◽

3 Dimensional ◽

Soft Gels ◽

Cell Motion

This study developed a digital volume correlation (DVC) algorithm based on fast normalized cross-correlation to measure the 3-dimensional deformation of soft gels, which was further utilized as a force sensor for cell mechanics studies. The developed algorithm was applied to the 3-D volume images of a gel acquired by confocal microscope to measure the deformation of the gel. The gel contained uniformly-dispersed florescence-labeled microbeads so as to generate a necessary speckle pattern for cross-correlation. The developed algorithm has been validated both analytically and experimentally, and applied to investigate cell mechanics by measuring the displacement field induced by the cell motion. Then, surface traction force generated by cells can be quantified through the conventional linear elasticity theory without any further assumption.

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Laboratory Validation of Instrumented Mouthguard for Use in Sport

Sensors ◽

10.3390/s21186028 ◽

2021 ◽

Vol 21 (18) ◽

pp. 6028

Author(s):

Danyon Stitt ◽

Nick Draper ◽

Keith Alexander ◽

Natalia Kabaliuk

Keyword(s):

Linear Acceleration ◽

Systematic Bias ◽

Strongly Correlated ◽

Rotational Acceleration ◽

Sports Performance ◽

Kinematic Parameters ◽

Measuring Head ◽

Head Impacts ◽

Inherent Risk ◽

Measurement Devices

Concussion is an inherent risk of participating in contact, combat, or collision sports, within which head impacts are numerous. Kinematic parameters such as peak linear and rotational acceleration represent primary measures of concussive head impacts. The ability to accurately measure and categorise such impact parameters in real time is important in health and sports performance contexts. The purpose of this study was to assess the accuracy of the latest HitIQ Nexus A9 instrumented mouthguard (HitIQ Pty. Ltd. Melbourne Australia) against reference sensors in an aluminium headform. The headform underwent drop testing at various impact intensities across the NOCSAE-defined impact locations, comparing the peak linear and rotational acceleration (PLA and PRA) as well as the shapes of the acceleration time-series traces for each impact. Mouthguard PLA and PRA measurements strongly correlated with (R2 = 0.996 and 0.994 respectively), and strongly agreed with (LCCC = 0.997) the reference sensors. The root mean square error between the measurement devices was 1 ± 0.6g for linear acceleration and 47.4 ± 35 rad/s2 for rotational acceleration. A Bland–Altman analysis found a systematic bias of 1% for PRA, with no significant bias for PLA. The instrumented mouthguard displayed high accuracy when measuring head impact kinematics in a laboratory setting.

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The Ability of American Football Helmets to Manage Linear Acceleration With Repeated High-Energy Impacts

Journal of Athletic Training ◽

10.4085/1062-6050-51.4.08 ◽

2016 ◽

Vol 51 (3) ◽

pp. 258-263 ◽

Cited By ~ 9

Author(s):

Janie Cournoyer ◽

Andrew Post ◽

Philippe Rousseau ◽

Blaine Hoshizaki

Keyword(s):

Linear Acceleration ◽

High Energy ◽

American Football ◽

Football Players ◽

Multiple Impacts ◽

Head Impacts ◽

Football Helmet ◽

Acceleration Data ◽

Football Helmets ◽

Injury Causation

Football players can receive up to 1400 head impacts per season, averaging 6.3 impacts per practice and 14.3 impacts per game. A decrease in the capacity of a helmet to manage linear acceleration with multiple impacts could increase the risk of traumatic brain injury.Context: To investigate the ability of football helmets to manage linear acceleration with multiple high-energy impacts.Objective: Descriptive laboratory study.Design: Laboratory.Setting: We collected linear-acceleration data for 100 impacts at 6 locations on 4 helmets of different models currently used in football. Impacts 11 to 20 were compared with impacts 91 to 100 for each of the 6 locations.Main Outcome Measure(s): Linear acceleration was greater after multiple impacts (91−100) than after the first few impacts (11−20) for the front, front-boss, rear, and top locations. However, these differences are not clinically relevant as they do not affect the risk for head injury.Results: American football helmet performance deteriorated with multiple impacts, but this is unlikely to be a factor in head-injury causation during a game or over a season.Conclusions:

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Three-Dimensional Reconstruction Using Stereo Pairs from Serial Thick Sections

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100080249 ◽

1977 ◽

Vol 35 ◽

pp. 562-563

Author(s):

Robert Glaeser ◽

Thomas Bauer ◽

David Grano

Keyword(s):

Three Dimensional ◽

Dimensional Structure ◽

Serial Sections ◽

Thin Sections ◽

3 Dimensional ◽

Transmission Electron ◽

Freeze Dried ◽

Dimensional Reconstruction ◽

Stereo Imagery ◽

Whole Mounts

In transmission electron microscopy, the 3-dimensional structure of an object is usually obtained in one of two ways. For objects which can be included in one specimen, as for example with elements included in freeze- dried whole mounts and examined with a high voltage microscope, stereo pairs can be obtained which exhibit the 3-D structure of the element. For objects which can not be included in one specimen, the 3-D shape is obtained by reconstruction from serial sections. However, without stereo imagery, only detail which remains constant within the thickness of the section can be used in the reconstruction; consequently, the choice is between a low resolution reconstruction using a few thick sections and a better resolution reconstruction using many thin sections, generally a tedious chore. This paper describes an approach to 3-D reconstruction which uses stereo images of serial thick sections to reconstruct an object including detail which changes within the depth of an individual thick section.

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Structural preservation and absolute contrast of catalase crystal sections prepared with tannic acid

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010007597x ◽

1983 ◽

Vol 41 ◽

pp. 448-449

Author(s):

C.W. Akey ◽

M. Szalay ◽

S.J. Edelstein

Keyword(s):

Tannic Acid ◽

Beef Heart ◽

X Rays ◽

Screw Axis ◽

General Applicability ◽

Thin Sections ◽

Beef Liver ◽

3 Dimensional ◽

Dimensional Reconstruction ◽

Structural Preservation

Three methods of obtaining 20 Å resolution in sectioned protein crystals have recently been described. They include tannic acid fixation, low temperature embedding and grid sectioning. To be useful for 3-dimensional reconstruction thin sections must possess suitable resolution, structural fidelity and a known contrast. Tannic acid fixation appears to satisfy the above criteria based on studies of crystals of Pseudomonas cytochrome oxidase, orthorhombic beef liver catalase and beef heart F1-ATPase. In order to develop methods with general applicability, we have concentrated our efforts on a trigonal modification of catalase which routinely demonstrated a resolution of 40 Å. The catalase system is particularly useful since a comparison with the structure recently solved with x-rays will permit evaluation of the accuracy of 3-D reconstructions of sectioned crystals.Initially, we re-evaluated the packing of trigonal catalase crystals studied by Longley. Images of the (001) plane are of particular interest since they give a projection down the 31-screw axis in space group P3121. Images obtained by the method of Longley or by tannic acid fixation are negatively contrasted since control experiments with orthorhombic catalase plates yield negatively stained specimens with conditions used for the larger trigonal crystals.

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