The Effect of Vertical and Multiplanar Accelerations on Differing Production Seat Belt Sensor Designs

2008 ◽  
Author(s):  
Steven E. Meyer ◽  
Arin A. Oliver ◽  
Davis A. Hock ◽  
Joshua D. Hayden ◽  
Stephen M. Forrest ◽  
...  
Keyword(s):  
Real World ◽  
Inertial Sensors ◽  
Inertial Sensor ◽  
Seat Belt ◽  
Design Feature ◽  
Test Methods ◽  
Center Of Gravity ◽  
Restraint System ◽  
Occupant Injury ◽  
Cup Design

In real world accidents, vehicles are often subjected to multiplanar crash environments such as those seen in multiple impacts or rollover collisions. These various impact environments can directly affect the accelerations experienced by the vehicle and its components. Particularly vulnerable is the vehicle sensitive (inertially activated) crash sensor that is commonly used in seat belt retractor design. Though these designs have been proven effective in the frontal crash environments, they have also been shown to be susceptible to unlocking and/or a delay in lockup by vertical and/or rotational accelerations [1–3]. Such delayed retractor response can result in belt webbing payout and significant occupant motion within the restraint system. This can increase the likelihood and severity of occupant injury within the vehicle and/or injury from partial or full ejection in rollovers. Occurrence of this phenomenon in the real world has been documented and previously published [4, 5]. Evidence of retractor sensor unlocking and resulting spoolout includes identifiable forensic markings on the restraint system components [6] as well as occupant excursion evidence including full ejection and excessive partial ejection of properly belted vehicle occupants. The subject paper will follow previously published test methodologies [1–3] and report on new testing conducted on four differing production seat belt retractor designs. The test methods include linear accelerator tests to document the effects of a vertical pulse on an inertially sensitive retractor and, secondly, rotational accelerator tests wherein the retractors were mounted on a rotating fixture and subjected to various roll rates. Two tested retractors are the ball and cup design with the retractor’s inertial sensor incorporated within the retractor mounted in the vehicle’s roof pillars. The other two tested retractor designs utilize remote mounted (near the vehicle’s center of gravity) inertial sensors. These retractors are biased to the locked position via a spring and are held unlocked only when a solenoid is energized by the vehicle’s remote inertial sensor. For the rotational acceleration tests, the retractors were mounted in similar positions to that seen in their respective production vehicles relative to the vehicle’s center of gravity. Two retractors were then tested concurrently on the same test apparatus such that they were subjected to equivalent multiplanar environments, and thus allowed for direct comparison of their retractor design sensitivities and lockup performance. Additionally, a vehicle pillar mounted retractor was tested with and without a webbing sensitive lockup feature to allow for analysis of this design feature in varying multiplanar environments. The retractors’ performance under both the linear/vertical and rollover test conditions were noticeably different and are analyzed in detail.

scholarly journals Re-Enactment as a Method to Reproduce Real-World Fall Events Using Inertial Sensor Data: Development and Usability Study

10.2196/13961 ◽  
2020 ◽  
Vol 22 (4) ◽  
pp. e13961
Author(s):  
Kim Sarah Sczuka ◽  
Lars Schwickert ◽  
Clemens Becker ◽  
Jochen Klenk
Keyword(s):  
Real World ◽  
Independent Living ◽  
Inertial Sensors ◽  
Inertial Sensor ◽  
Center Of Mass ◽  
Fall Detection ◽  
Video Data ◽  
Sensor Data ◽  
Movement Behavior ◽  
The Real

Background Falls are a common health problem, which in the worst cases can lead to death. To develop reliable fall detection algorithms as well as suitable prevention interventions, it is important to understand circumstances and characteristics of real-world fall events. Although falls are common, they are seldom observed, and reports are often biased. Wearable inertial sensors provide an objective approach to capture real-world fall signals. However, it is difficult to directly derive visualization and interpretation of body movements from the fall signals, and corresponding video data is rarely available. Objective The re-enactment method uses available information from inertial sensors to simulate fall events, replicate the data, validate the simulation, and thereby enable a more precise description of the fall event. The aim of this paper is to describe this method and demonstrate the validity of the re-enactment approach. Methods Real-world fall data, measured by inertial sensors attached to the lower back, were selected from the Fall Repository for the Design of Smart and Self-Adaptive Environments Prolonging Independent Living (FARSEEING) database. We focused on well-described fall events such as stumbling to be re-enacted under safe conditions in a laboratory setting. For the purposes of exemplification, we selected the acceleration signal of one fall event to establish a detailed simulation protocol based on identified postures and trunk movement sequences. The subsequent re-enactment experiments were recorded with comparable inertial sensor configurations as well as synchronized video cameras to analyze the movement behavior in detail. The re-enacted sensor signals were then compared with the real-world signals to adapt the protocol and repeat the re-enactment method if necessary. The similarity between the simulated and the real-world fall signals was analyzed with a dynamic time warping algorithm, which enables the comparison of two temporal sequences varying in speed and timing. Results A fall example from the FARSEEING database was used to show the feasibility of producing a similar sensor signal with the re-enactment method. Although fall events were heterogeneous concerning chronological sequence and curve progression, it was possible to reproduce a good approximation of the motion of a person’s center of mass during fall events based on the available sensor information. Conclusions Re-enactment is a promising method to understand and visualize the biomechanics of inertial sensor-recorded real-world falls when performed in a suitable setup, especially if video data is not available.

scholarly journals An Inertial Sensor-Based Gait Analysis Pipeline for the Assessment of Real-World Stair Ambulation Parameters

Sensors ◽  
2021 ◽  
Vol 21 (19) ◽  
pp. 6559
Author(s):  
Nils Roth ◽  
Arne Küderle ◽  
Dominik Prossel ◽  
Heiko Gassner ◽  
Bjoern M. Eskofier ◽  
...  
Keyword(s):  
Gait Analysis ◽  
Real World ◽  
Inertial Sensors ◽  
Inertial Sensor ◽  
Analysis Pipeline ◽  
Postural Control System ◽  
Mobility Impairments ◽  
Spatial Features ◽  
Level Walking ◽  
Stair Ambulation

Climbing stairs is a fundamental part of daily life, adding additional demands on the postural control system compared to level walking. Although real-world gait analysis studies likely contain stair ambulation sequences, algorithms dedicated to the analysis of such activities are still missing. Therefore, we propose a new gait analysis pipeline for foot-worn inertial sensors, which can segment, parametrize, and classify strides from continuous gait sequences that include level walking, stair ascending, and stair descending. For segmentation, an existing approach based on the hidden Markov model and a feature-based gait event detection were extended, reaching an average segmentation F1 score of 98.5% and gait event timing errors below ±10ms for all conditions. Stride types were classified with an accuracy of 98.2% using spatial features derived from a Kalman filter-based trajectory reconstruction. The evaluation was performed on a dataset of 20 healthy participants walking on three different staircases at different speeds. The entire pipeline was additionally validated end-to-end on an independent dataset of 13 Parkinson’s disease patients. The presented work aims to extend real-world gait analysis by including stair ambulation parameters in order to gain new insights into mobility impairments that can be linked to clinically relevant conditions such as a patient’s fall risk and disease state or progression.

Restraint System Performance and Injury Potential to Belted Occupants in Automobile Rollover Crashes

2006 ◽  
Author(s):  
Steven E. Meyer ◽  
Steven Forrest ◽  
Brian Herbst
Keyword(s):  
Real World ◽  
Dynamic Testing ◽  
Seat Belt ◽  
Restraint System ◽  
Structure Damage ◽  
Complete Vehicle ◽  
Increased Risk ◽  
Vehicle Components ◽  
Occupant Kinematics ◽  
Injury Potential

It has long been recognized within the automotive safety community and by numerous biomechanical research studies that providing effective occupant protection in automotive rollover crashes requires effective occupant restraint. Effective occupant restraint includes, at the most basic level, preventing occupant ejection and providing sufficient control of occupant kinematics through the rollover event to prevent potentially injurious contacts with interior vehicle components. This paper examines both laboratory and real-world accident analysis of restraint performance in rollover-type environments. This includes studies involving static and dynamic testing with human surrogates and anthropometric test devices (ATDs). Additionally, the effects of rollover roof deformation on the restraint systems ability to control or affect occupant kinematics, when those restraint systems are anchored to the dynamically deforming structural components of the vehicle, are examined. Finally, various production and alternative restraint system designs are considered and discussed relative to their ability to control occupant kinematics and their influence on belted occupants' injury potential in the rollover crash mode. This paper will focus on the effect of seat belt looseness, or slack, and its relationship to occupant excursion during a rollover. Literature is referenced establishing that increased occupant excursion produces increased injury potential in rollovers, both by increasing the likelihood of injurious contacts with interior vehicle components as well as an increased risk of full and partial ejection. Four complete vehicle inversion studies (spit tests) are conducted with live surrogate occupants in production vehicle restraint systems. These studies document occupant excursions under a 1G inverted environment with various amounts of seat belt slack in production restraint systems as well as comparison tests using various alternative restraint configurations. Additionally three complete vehicle inverted drop tests are conducted in which the vehicles' roof structures and the upper torso belt anchors (D-ring) are instrumented to document their displacement while producing typical real-world type roof structure damage. The effect of this restraint anchor deformation is then examined relative to the occupant excursions evaluated in the spit tests. Lastly, a complete dolly rollover test conducted on a contemporary production mini van with production restrained anthropometric test devices (ATDs) is examined with a focus on the restraint system's geometry alterations and effectiveness through the multiple roll/roof contact events.

scholarly journals Reference in-vitro dataset for inertial-sensor-to-bone alignment applied to the tibiofemoral joint

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Ive Weygers ◽  
Manon Kok ◽  
Thomas Seel ◽  
Darshan Shah ◽  
Orçun Taylan ◽  
...  
Keyword(s):  
Inertial Sensors ◽  
Inertial Sensor ◽  
Ground Truth ◽  
Transformation Matrices ◽  
True Model ◽  
Advance Research ◽  
Manual Palpation ◽  
Visualization Tools ◽  
Inertial Measurements

AbstractSkin-attached inertial sensors are increasingly used for kinematic analysis. However, their ability to measure outside-lab can only be exploited after correctly aligning the sensor axes with the underlying anatomical axes. Emerging model-based inertial-sensor-to-bone alignment methods relate inertial measurements with a model of the joint to overcome calibration movements and sensor placement assumptions. It is unclear how good such alignment methods can identify the anatomical axes. Any misalignment results in kinematic cross-talk errors, which makes model validation and the interpretation of the resulting kinematics measurements challenging. This study provides an anatomically correct ground-truth reference dataset from dynamic motions on a cadaver. In contrast with existing references, this enables a true model evaluation that overcomes influences from soft-tissue artifacts, orientation and manual palpation errors. This dataset comprises extensive dynamic movements that are recorded with multimodal measurements including trajectories of optical and virtual (via computed tomography) anatomical markers, reference kinematics, inertial measurements, transformation matrices and visualization tools. The dataset can be used either as a ground-truth reference or to advance research in inertial-sensor-to-bone-alignment.

scholarly journals Smartphone-Based Inertial Odometry for Blind Walkers

Sensors ◽  
2021 ◽  
Vol 21 (12) ◽  
pp. 4033
Author(s):  
Peng Ren ◽  
Fatemeh Elyasi ◽  
Roberto Manduchi
Keyword(s):  
Particle Filtering ◽  
Inertial Sensors ◽  
State Of The Art ◽  
Inertial Sensor ◽  
Mean Shift ◽  
Gait Pattern ◽  
Comparative Assessment ◽  
Pedestrian Tracking ◽  
Step Counter ◽  
Assisted Navigation

Pedestrian tracking systems implemented in regular smartphones may provide a convenient mechanism for wayfinding and backtracking for people who are blind. However, virtually all existing studies only considered sighted participants, whose gait pattern may be different from that of blind walkers using a long cane or a dog guide. In this contribution, we present a comparative assessment of several algorithms using inertial sensors for pedestrian tracking, as applied to data from WeAllWalk, the only published inertial sensor dataset collected indoors from blind walkers. We consider two situations of interest. In the first situation, a map of the building is not available, in which case we assume that users walk in a network of corridors intersecting at 45° or 90°. We propose a new two-stage turn detector that, combined with an LSTM-based step counter, can robustly reconstruct the path traversed. We compare this with RoNIN, a state-of-the-art algorithm based on deep learning. In the second situation, a map is available, which provides a strong prior on the possible trajectories. For these situations, we experiment with particle filtering, with an additional clustering stage based on mean shift. Our results highlight the importance of training and testing inertial odometry systems for assisted navigation with data from blind walkers.

scholarly journals Inertial Sensor Reliability and Validity for Static and Dynamic Balance in Healthy Adults: A Systematic Review

Sensors ◽  
2021 ◽  
Vol 21 (15) ◽  
pp. 5167
Author(s):  
Nicky Baker ◽  
Claire Gough ◽  
Susan J. Gordon
Keyword(s):  
Systematic Review ◽  
Discriminant Validity ◽  
Inertial Sensors ◽  
Postural Sway ◽  
Inertial Sensor ◽  
Dynamic Balance ◽  
Healthy Adults ◽  
Gait Velocity ◽  
Time Data ◽  
Targeted Interventions

Compared to laboratory equipment inertial sensors are inexpensive and portable, permitting the measurement of postural sway and balance to be conducted in any setting. This systematic review investigated the inter-sensor and test-retest reliability, and concurrent and discriminant validity to measure static and dynamic balance in healthy adults. Medline, PubMed, Embase, Scopus, CINAHL, and Web of Science were searched to January 2021. Nineteen studies met the inclusion criteria. Meta-analysis was possible for reliability studies only and it was found that inertial sensors are reliable to measure static standing eyes open. A synthesis of the included studies shows moderate to good reliability for dynamic balance. Concurrent validity is moderate for both static and dynamic balance. Sensors discriminate old from young adults by amplitude of mediolateral sway, gait velocity, step length, and turn speed. Fallers are discriminated from non-fallers by sensor measures during walking, stepping, and sit to stand. The accuracy of discrimination is unable to be determined conclusively. Using inertial sensors to measure postural sway in healthy adults provides real-time data collected in the natural environment and enables discrimination between fallers and non-fallers. The ability of inertial sensors to identify differences in postural sway components related to altered performance in clinical tests can inform targeted interventions for the prevention of falls and near falls.

scholarly journals Finger and foot tapping sensor system for objective motor assessment

2018 ◽  
Vol 75 (1) ◽  
pp. 68-77 ◽  
Author(s):  
Milica Djuric-Jovicic ◽  
Nenad Jovicic ◽  
Sasa Radovanovic ◽  
Milica Jecmenica-Lukic ◽  
Minja Belic ◽  
...  
Keyword(s):  
Healthy Subjects ◽  
Motor Performance ◽  
Graphical Representation ◽  
Inertial Sensors ◽  
Inertial Sensor ◽  
Quantitative Estimation ◽  
Objective Assessment ◽  
Force Sensor ◽  
Neurological Patient ◽  
Foot Tapping

Background/Aim. Finger tapping test is commonly used in neurological examinations as a test of motor performance. The new system comprising inertial and force sensors and custom proprietary software was developed for quantitative estimation and assessment of finger and foot tapping tests. The aim of this system was to provide diagnosis support and objective assessment of motor function. Methods. Miniature inertial sensors were placed on fingertips and used for measuring finger movements. A force sensor was placed on the fingertip of one finger, in order to measure the force during tapping. For foot tapping assessment, an inertial sensor was mounted on the subject?s foot, which was placed above a force platform. By using this system, various parameters such as a number of taps, tapping duration, rhythm, open and close speed, the applied force and tapping angle, can be extracted for detailed analysis of a patient?s motor performance. The system was tested on 13 patients with Parkinson?s disease and 14 healthy controls. Results. The system allowed easy measurement of listed parameters, and additional graphical representation showed quantitative differences in these parameters between neurological patient and healthy subjects. Conclusion. The novel system for finger and foot tapping test is compact, simple to use and efficiently collects patient data. Parameters measured in patients can be compared to those measured in healthy subjects, or among groups of patients, or used to monitor progress of the disease, or therapy effects. Created data and scores could be used together with the scores from clinical tests, providing the possibility for better insight into the diagnosis.

A new method to reduce the noise of the miniaturised inertial sensors disposed in redundant linear configurations

2013 ◽  
Vol 117 (1188) ◽  
pp. 111-132 ◽  
Author(s):  
T. L. Grigorie ◽  
R. M. Botez
Keyword(s):  
Inertial Sensors ◽  
Inertial Sensor ◽  
Low Frequency ◽  
Minimum Variance ◽  
Measurement Unit ◽  
Time Step ◽  
Accelerometer Sensor ◽  
Sensor Model ◽  
Input Acceleration

Abstract This paper presents a new adaptive algorithm for the statistical filtering of miniaturised inertial sensor noise. The algorithm uses the minimum variance method to perform a best estimate calculation of the accelerations or angular speeds on each of the three axes of an Inertial Measurement Unit (IMU) by using the information from some accelerometers and gyros arrays placed along the IMU axes. Also, the proposed algorithm allows the reduction of both components of the sensors’ noise (long term and short term) by using redundant linear configurations for the sensors dispositions. A numerical simulation is performed to illustrate how the algorithm works, using an accelerometer sensor model and a four-sensor array (unbiased and with different noise densities). Three cases of ideal input acceleration are considered: 1) a null signal; 2) a step signal with a no-null time step; and 3) a low frequency sinusoidal signal. To experimentally validate the proposed algorithm, some bench tests are performed. In this way, two sensors configurations are used: 1) one accelerometers array with four miniaturised sensors (n = 4); and 2) one accelerometers array with nine miniaturised sensors (n = 9). Each of the two configurations are tested for three cases of input accelerations: 0ms−1, 9·80655m/s2 and 9·80655m/s2.

scholarly journals Comparative Analysis of Inertial Sensor to Optical Motion Capture System Performance in Push-Pull Exertion Postures

2016 ◽  
Vol 60 (1) ◽  
pp. 970-974 ◽  
Author(s):  
Sol Lim ◽  
Andrea Case ◽  
Clive D’Souza
Keyword(s):  
Motion Capture ◽  
Inertial Sensors ◽  
Inertial Sensor ◽  
Interactive Effects ◽  
Flexion Angle ◽  
Task Demand ◽  
Optical Motion ◽  
Physical Task ◽  
Target Force ◽  
Optical Motion Capture

This study examined interactions between inertial sensor (IS) performance and physical task demand on posture kinematics in a two-handed force exertion task. Fifteen male individuals participated in a laboratory experiment that involved exerting a two-handed isometric horizontal force on an instrumented height-adjustable handle. Physical task demand was operationalized by manipulating vertical handle height, target force magnitude, and force direction. These factors were hypothesized to influence average estimates of torso flexion angle measured using inertial sensors and an optical motion capture (MC) system, as well as the root mean squared errors (RMSE) between instrumentation computed over a 3s interval of the force exertion task. Results indicate that lower handle heights and higher target force levels were associated with increased torso and pelvic flexion in both, push and pull exertions. Torso flexion angle estimates obtained from IS and MC did not differ significantly. However, RMSE increased with target force intensity suggesting potential interactive effects between measurement error and physical task demand.

MEMS Inertial Sensor Fault Diagnosis Using a CNN-Based Data-Driven Method

2020 ◽  
Vol 34 (14) ◽  
pp. 2059048
Author(s):  
Tong Gao ◽  
Wei Sheng ◽  
Mingliang Zhou ◽  
Bin Fang ◽  
Liping Zheng
Keyword(s):  
Fault Diagnosis ◽  
Adaptive Learning ◽  
Inertial Sensors ◽  
Inertial Sensor ◽  
Optimization Method ◽  
Learning Rate ◽  
Data Driven ◽  
Adaptive Learning Rate ◽  
Improved Performance ◽  
Rate Optimization

In this paper, we propose a novel fault diagnosis (FD) approach for micro-electromechanical systems (MEMS) inertial sensors that recognize the fault patterns of MEMS inertial sensors in an end-to-end manner. We use a convolutional neural network (CNN)-based data-driven method to classify the temperature-related sensor faults in unmanned aerial vehicles (UAVs). First, we formulate the FD problem for MEMS inertial sensors into a deep learning framework. Second, we design a multi-scale CNN which uses the raw data of MEMS inertial sensors as input and which outputs classification results indicating faults. Then we extract fault features in the temperature domain to solve the non-uniform sampling problem. Finally, we propose an improved adaptive learning rate optimization method which accelerates the loss convergence by using the Kalman filter (KF) to train the network efficiently with a small dataset. Our experimental results show that our method achieved high fault recognition accuracy and that our proposed adaptive learning rate method improved performance in terms of loss convergence and robustness on a small training batch.

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