Head Restraint Research Articles

The Influence of Enhanced Side Impact Protection on Kinematics and Injury Measures of Far- or Center-Seated Children in Forward-Facing Child Restraints

Objective: To evaluate the influence of forward-facing child restraint systems’ (FFCRSs) side impact structure, such as side wings, on the head kinematics and response of a restrained, far- or center-seated 3-year-old anthropomorphic test device (ATD) in oblique sled tests.Methods: Sled tests were conducted utilizing an FFCRS with large side wings and with the side wings removed. The CRS were attached via LATCH on 2 different vehicle seat fixtures—a small SUV rear bench seat and minivan rear bucket seat—secured to the sled carriage at 20° from lateral. Four tests were conducted on each vehicle seat fixture, 2 for each FFCRS configuration. A Q3s dummy was positioned in FFCRS according to the CRS owner's manual and FMVSS 213 procedures. The tests were conducted using the proposed FMVSS 213 side impact pulse. Three-dimensional motion cameras collected head excursion data. Relevant data collected during testing included the ATD head excursions, head accelerations, LATCH belt loads, and neck loads.Results: Results indicate that side wings have little influence on head excursions and ATD response. The median lateral head excursion was 435 mm with side wings and 443 mm without side wings. The primary differences in head response were observed between the 2 vehicle seat fixtures due to the vehicle seat head restraint design. The bench seat integrated head restraint forced a tether routing path over the head restraint. Due to the lateral crash forces, the tether moved laterally off the head restraint reducing tension and increasing head excursion (477 mm median). In contrast, when the tether was routed through the bucket seat's adjustable head restraint, it maintained a tight attachment and helped control head excursion (393 mm median).Conclusion: This testing illustrated relevant side impact crash circumstances where side wings do not provide the desired head containment for a 3-year-old ATD seated far-side or center in FFCRS. The head appears to roll out of the FFCRS even in the presence of side wings, which may expose the occupant to potential head impact injuries. We postulate that in a center or far-side seating configuration, the absence of door structure immediately adjacent to the CRS facilitates the rotation and tipping of the FFCRS toward the impact side and the roll-out of the head around the side wing structure. Results suggest that other prevention measures, in the form of alternative side impact structure design, FFCRS vehicle attachment, or shared protection between the FFCRS and the vehicle, may be necessary to protect children in oblique side impact crashes.

Investigation of Child Restraint System (CRS) Compatibility in the Vehicle Seat Environment

Objective: Child restraint system (CRS) misuse is common and can have serious consequences to child safety. Physical incompatibilities between CRS and vehicles can complicate the installation process and may worsen CRS misuse rates. This study aims to identify the most common sources of incompatibility between representative groups of CRS and vehicles.Methods: Detailed dimensional data were collected from 59 currently marketed CRS and 61 late model vehicles. Key dimensions were compared across all 3,599 theoretical CRS/vehicle combinations and the most common predicted incompatibilities were determined. A subset of 34 physical installations was analyzed to validate the results.Results: Only 58.2% of rear-facing (RF) CRS/vehicle combinations were predicted to have proper agreement between the vehicle's seat pan angle and the CRS manufacturers’ required base angle. The width of the base of the CRS was predicted to fit snugly between the vehicle's seat pan bolsters in 63.3% of RF CRS/vehicle combinations and 62.2% of forward-facing (FF) CRS/vehicle combinations. FF CRS were predicted to be free of interaction with the vehicle's head restraint in 66.4% of combinations. Roughly 90.0% of RF CRS/vehicle combinations were predicted to have enough horizontal clearance space to set the front seat in the middle its fore/aft slider track. Compatibility rates were above 98% regarding the length of the CRS base compared to the length of the vehicle seat pan and the ability of the top tether to reach the tether anchor. Validation studies revealed that the predictions of RF CRS base angle range vs. seat pan angle compatibility were accurate within 6%, and head restraint interference and front row clearance incompatibilities may be more common than the dimensional analysis approach has predicted.Conclusions: The results of this study indicate that RF CRS base angles and front row clearance space, as well as FF CRS head restraint interference, are frequent compatibility concerns. These results enable manufacturers, researchers, and consumers to focus their attention on the most relevant CRS/vehicle incompatibility issues in today's market.

DESIGN PARAMETERS OF DRIVER SEAT IN AN AUTOMOBILE

Driver seat is an important system of any automobile, it is also complicated system consists of so many parts, adjustments as well as safety systems. A seat adjustment includes height adjustment, fore and aft adjustment, back recline adjustments. Safety systems include seat belts, air bags and advanced head restraints. Generally professional driver works more than eight hours per day of a week, therefore driver seat must be designed by considering all the parameters. Also uneven road condition induces the vibration in a vehicle transmitted to driver body. Poorly designed driver seat affects the driver health and psychological conditions of mind. Three main objectives of any driver seats are safety, health and comfort of driver. This paper presents all the parameters of driver seat such as anthropometry of human, ergonomics related parameters, seat materials, safety related parameters, comfort related parameters as well as weight and aesthetics with classifications and basics of driver seat.

Non-invasive primate head restraint using thermoplastic masks

BackgroundThe success of many neuroscientific studies depends upon adequate head fixation of awake, behaving animals. Typically, this is achieved by surgically affixing a head-restraint prosthesis to the skull. New methodHere we report the use of thermoplastic masks to non-invasively restrain monkeys’ heads. Mesh thermoplastic sheets become pliable when heated and can then be molded to an individual monkey's head. After cooling, the custom mask retains this shape indefinitely for day-to-day use. ResultsWe successfully trained rhesus macaques (Macaca mulatta) to perform cognitive tasks while wearing thermoplastic masks. Using these masks, we achieved a level of head stability sufficient for high-resolution eye-tracking and intracranial electrophysiology. Comparison with existing methodCompared with traditional head-posts, we find that thermoplastic masks perform at least as well during infrared eye-tracking and single-neuron recordings, allow for clearer magnetic resonance image acquisition, enable freer placement of a transcranial magnetic stimulation coil, and impose lower financial and time costs on the lab. ConclusionsWe conclude that thermoplastic masks are a viable non-invasive form of primate head restraint that enable a wide range of neuroscientific experiments.

Vehicle Occupant Head Position Quantification Using an Array of Capacitive Proximity Sensors

Currently, proper vehicle head restraint (HR) positioning requires manual adjustment and knowledge on the part of the occupant. By removing the requirement for manual adjustment, an HR positioning system that autonomously moves and adapts the HR position properly to any seated occupant could serve to reduce the social and personal costs of whiplash injuries, as compared with existing manual systems. To achieve this, quantification of the occupant's head position relative to the HR is required. In a previous paper, a rectangular capacitive proximity-sensing array for the purpose of occupant head position quantification was studied. Here, a range-maximized sensor was first designed to reduce electrostatic and environmental disturbances. To achieve this, numerical modeling and laboratory experiments were conducted, and then, a design process for an interdigitated comb-shaped sensor geometry was proposed to maximize the sensing range of the sensor. The effects of temperature and humidity on the sensor were also evaluated and compensated. A novel capacitive proximity-sensing array was then designed, which had the minimum number of the aforementioned comb-shaped sensors necessary for accurately estimating the 3-D position of an occupant's head in near real time. This estimation was carried out using a nonparametric neural network. The above capacitive array was then integrated and fully contained in a customized HR as part of a vehicle seat safety system. The system was tested and demonstrated that such a head position sensing methodology would be capable of autonomously positioning an HR to meet the guidelines of the Insurance Institute for Highway Safety (IIHS).

Juxtacellular Monitoring and Localization of Single Neurons within Sub-cortical Brain Structures of Alert, Head-restrained Rats.

There are a variety of techniques to monitor extracellular activity of single neuronal units. However, monitoring this activity from deep brain structures in behaving animals remains a technical challenge, especially if the structures must be targeted stereotaxically. This protocol describes convenient surgical and electrophysiological techniques that maintain the animal's head in the stereotaxic plane and unambiguously isolate the spiking activity of single neurons. The protocol combines head restraint of alert rodents, juxtacellular monitoring with micropipette electrodes, and iontophoretic dye injection to identify the neuron location in post-hoc histology. While each of these techniques is in itself well-established, the protocol focuses on the specifics of their combined use in a single experiment. These neurophysiological and neuroanatomical techniques are combined with behavioral monitoring. In the present example, the combined techniques are used to determine how self-generated vibrissa movements are encoded in the activity of neurons within the somatosensory thalamus. More generally, it is straightforward to adapt this protocol to monitor neuronal activity in conjunction with a variety of behavioral tasks in rats, mice, and other animals. Critically, the combination of these methods allows the experimenter to directly relate anatomically-identified neurophysiological signals to behavior.

Evaluation of ISO CRS Envelopes Relative to U.S. Vehicles and Child Restraint Systems

Objectives: The objectives of this study are to use computer simulation to evaluate the International Organization for Standardization (ISO) 13216-3:2006(E) child restraint system (CRS) envelopes relative to rear seat compartments from vehicles and CRSs in the U.S. market, investigate the potential compatibility issues of U.S. vehicles and CRSs, and demonstrate whether necessary modifications can be made to introduce such a system into compatibility evaluations between U.S. vehicles and CRSs.Methods: Three-dimensional geometry models for 26 vehicles and 16 convertible CRS designs developed previously were used. Geometry models of 3 forward-facing and 3 rear-facing CRS envelopes provided by the ISO were built in the current study. The virtual fit process closely followed the physical procedures described in the ISO standards.Results: The results showed that the current ISO rear-facing envelopes can provide reasonable classifications for CRSs and vehicles, but the forward-facing envelopes do not represent products currently in the U.S. market. In particular, all of the selected vehicles could accommodate the largest forward-facing CRS envelope at the second-row seat location behind the driver seat. In contrast, half of the selected CRSs could not fit within any of the forward-facing ISO CRS envelopes, mainly due to protrusion at the rear-top corner of the envelope. The results also indicate that the rear seat compartment in U.S. vehicles often cannot accommodate a large portion of convertible CRSs in the rear-facing position. The increased demand for vehicle fuel economy and the recommendation to keep children rear-facing longer may lead to smaller cars and larger CRSs, which may increase the potential for fit problems.Conclusions: The virtual classifications indicated that contact between the forward-facing CRSs and the head restraints in the rear seats as well as that between the rear-facing CRSs and the back of the front seats is a main concern regarding the compatibility between the vehicles and the CRSs. Therefore, modification of the current ISO forward-facing CRS envelopes will likely to be necessary to ensure that they are useful for the U.S. market.

Research on Safety Distance Mathematical Model of Pro-Active Head Restraint in Rear-end Collision Avoidance System

Pro-active head restraint is a new automotive safety device with both active safety and passive safety characteristics. It can make a pre-estimation of the occurrence possibility of rear-end collision. Thus, the whiplash injury can be effectively reduced or even prevented. One of the key elements in rear-end collision avoidance system is to establish an effective safety distance mathematical model. Based on the running state of front car, the related calculation models of safety distance are established by means of dynamical and kinematical analysis of vehicle braking process and following process. Taken randomness and dynamic characteristics of parameters into consideration, the fuzzy relations between these parameters should be validated by means of fuzzy theory. Thus, it may accord with the actual driving conditions. By using the MATLAB software, the study shows that safety distance model and the methods used to determine parameters are reasonable, and the false alarm can be effectively minimized.

NUMERICAL SIMULATION OF ENERGY ABSORPTION IN POLYURETHANE FOAMS UNDER IMPACT

Selection of proper mechanical characteristics of the padding material of the head rest, namely polyurethane foam, is particularly important in the design process of the vehicle seat head restraint. In the paper the code of numerical simulation of flexible polyurethane foam absorber response against impact of a rigid body (passenger’s head) is presented. The code is based on the lump mass method. Basics of the numerical algorithm based on this method are presented. Material constitutive model of flexible polyurethane foam (FPF) derived on the basis of former experimental tests and used in the algorithm is described. Comparative results of numerical simulations together with results of experiments carried out on drop hammer rig with flat impact or are shown. The results are presented on diagrams of deceleration versus time. Also comparative Finite Element simulations are carried out. The FE simulation was performed using the implicit analysis, taking into account the multi-linear, hyper-elastic material model and large strain (non-linear geometric relations). The influence of damping coefficient on the deceleration characteristics was investigated. Some final conclusions concerning the applicability of the numerical code based on the lump mass method, as well as its advantages in comparison with the FE software are derived.

Active Head Restraints Used to Improve the Car Seats Safety in a Rear Impact Situation, in Accordance with the Requirements of EURO NCAP

This article is devoted to the urgent, presently, problem that is to ensure the best level of the passive safety of car seats with active head restraints, as well as to assess the effectiveness of such constructional designs. This is an impact-related task, to be, as a consequence, essentially nonlinear with large deformations, strains and accelerations. To solve this problem finite element models of three types of seat designs with active head restraints have been developed. When creating the simulation FEM a number of CAD (Computer Aided Design)/CAE (Computer Aided Engineering) software was used. This work was performed within the framework of the developed technique, which allows an efficient creation of the car seat designs with passive and active head restraints that meet requirements of the passive safety. The results of calculations and experiments allowed us to find that the active head restraint significantly reduced a NIC (Neck Injury Criterion) value, namely up to 36.92 (4%) when using the active headrest with articulated tilting couch, 29.23 (per 24%) when using the active headrest with sliding pad, and 26.15 (31%) when using the active head restraint, which is provided with an airbag. We have also managed to achieve significantly reduced head acceleration under impact. It was found that FEM seats with active head restraint, which is provided with an airbag, are the most secure because of the least NIC value under the impact (26.15). Presented in the article materials are used in teaching students at the department “Wheeled vehicles” of scientific and educational complex Special engineering in BMSTU.

Safety Distance Mathematical Model of Pro-Active Head Restraint Based on Fuzzy Theory

Pro-active head restraint is a new automotive safety device. It can make a pre-estimation of the occurrence possibility of rear-end collision. Thus, the whiplash injury can be effectively reduced or even prevented. One of the key elements in rear-end collision avoidance system is to establish an effective safety distance mathematical model. Based on the running state of front car, the related calculation models of safety distance are established by means of dynamical and kinematical analysis of vehicle braking process and following process. Taken randomness of parameters into consideration, the fuzzy relations between these parameters should be validated by means of fuzzy theory. By using the MATLAB software, the study shows that safety distance model and the methods used to determine parameters are reasonable, and the false alarm can be effectively minimized.

Update on the Effectiveness of High Retention Seats in Preventing Fatal Injury in Rear Impacts

Purpose: Starting in 1997, General Motors (GM) introduced high retention seats in new model vehicles to improve rear impact safety. The seat allowed the occupant to pocket into the seatback and had increased strength and improved head restraint coverage. The initial 4-year safety trends were evaluated using the 1991–2000 Fatality Analysis Reporting System (FARS). The reduction in odds of fatal injury was 30.4% (95% confidence interval [CI], 0.9–51.1, P <.05). This study updates the earlier one by adding 8 years of FARS data.Methods: The 2001–2008 FARS was analyzed for rear impacts of 1992 to 2008 model year GM vehicles that transitioned to high retention seats. The number of fatal and nonfatal injuries to drivers and right-front passengers was determined in vehicles with baseline (earlier designs) and high retention seats. The odds ratio for fatal injury and the change in fatality risk were determined with ±95% confidence intervals, z-statistic, and significance level. The data were further subdivided by passenger car, light truck (truck, SUV, and van) and driver-only crashes.Results: Based on 9,570 drivers and right-front passengers in fatal rear impacts in 1991–2008 FARS data, the fatality risk was 16.6% (95% CI, 15.1–18.3) in vehicles with high retention seats and 27.1% (95% CI, 26.1–28.1) in vehicles with baseline seats. The reduction in odds for fatal injury was 46.3% (95% CI, 39.3–52.4) with high retention seats and it was statistically significant with z = 9.982, P <.0001. The reduction in odds for fatal injury was similar for occupants in passenger cars at 45.4% (95% CI, 35.4–53.8) and light trucks, SUVs, and vans at 45.0% (95% CI, 28.8–57.5) using 2001–2008 FARS; however, the fatality risk was higher in passenger cars, at 23.1% (95% CI, 20.6–25.7), than in light trucks, SUVs, and vans, at 8.7% (95% CI, 7.0–10.7).Conclusions: Vehicles with high retention seats significantly reduced the odds for fatal injury by 46.3% (95% CI, 39.3–52.4, P <.0001) in rear impacts compared to vehicles with earlier seat designs. The new generation of yielding seats has significantly improved occupant safety in rear impacts.

Factors affecting tether use and correct use in child restraint installations

IntroductionField studies show that top tethers go unused in half of forward-facing child restraint installations. MethodIn this study, parent volunteers were asked to use the Lower Anchors and Tethers for Children (LATCH) to install child restraints in several vehicles to identify tether anchor characteristics that are associated with tether use. Thirty-seven volunteers were assigned to four groups. Each group tested two forward-facing child restraints in four of 16 vehicle models. Logistic regression models were used to identify predictors of tether use and correct use. ResultsSubjects used the tether in 89% of the 294 forward-facing child restraint installations and attached the tether correctly in 57% of the installations. Tethers were more likely to be used when the anchor was located on the rear deck as typically found in sedans compared with the seatback, floor, or roof. Tethers were less likely to be attached correctly when there was potentially confusing hardware present. No vehicle tether hardware characteristics or vehicle manual directions were associated specifically with correct tether routing and head restraint position. ConclusionThis study provides laboratory evidence that specific vehicle features are associated with tether use and correct use. Practical applicationsModifications to vehicles that make tether anchors easier to find and identify likely will result in increases in tether use and correct use.

Energy Absorption Device with Pendulum of Automobile Seats Head Restraints

According to the key parameters of automobile seats’ pendulum machine, a calculating method considering the anti-collision is proposed. Then the mathematical modeling of the pendulum system with actual working condition is established based on rigid body dynamical theories. With the momentum law and collision theory, a equation describes what condition for the center of collision and the point of impact to coincidence is derived. For system optimization, the minimal pendulum weight is taken as the objective function, multiple parameters as design variables, the pendulums’ optimum parameters are calculated by using mixed penalty function method.

J26 Portable Oculometric System for Quantitative Assessmentof Horizontal and Vertical Saccades in HD Monitoring

<h3>Background</h3> Saccadic eye movement parameters, such as its dynamics, latency and error rate are considered as a quantitative biomarkers of disease severity in HD. They possess potential for quick, non-invasive, objective assessment of cortical and sub-cortical function and when repeated systematically may allow easy tracking of disease progression or evaluation of novel therapies. Subjective evaluation of saccadic function is already included in UHDRS scale, however, most subtle features of saccadic movement cannot be observed without the instrumentation. On the other hand, application of the oculometric equipment is limited by its significantly high costs and complicated testing procedures. <h3>Methods/techniques</h3> Authors present Saccadometer Research XY, an integrated system dedicated for rapid, quantitative assessment of horizontal and vertical saccadic eye movement metrics in clinical environment. Subject’s eye movements are captured by a small factor, photo-electric sensor, designed for minimal setup and robust measurement. The stimuli is presented by an integrated, 8-targets laser stimuli generator, bound with the subject’s head, so that external stimuli display and head restraint are not required. The system provides pre programmed set of experiments for both reflex and volitional saccadic responses as well as build-in expert system for automatic saccade detection and classification. It allows to complete the testing procedure within several minutes. <h3>Conclusions</h3> Previous Saccadometer models have already proven its usefulness in examination of HD patients. The newest addition allows the measurement of vertical saccades, which are reported now to be more affected in HD than the horizontal.

Finite Element Models Development of Car Seats With Passive Head Restraints to Study Their Meeting Requirements for EURO NCAP

Finite Element Models Development of Car Seats With Passive Head Restraints to Study Their Meeting Requirements for EURO NCAP

Two-photon imaging of neural activity in awake mobile mice.

A method for functional, cellular-resolution imaging of neural populations in awake and mobile mice is presented here. The method is based on the use of a spherical treadmill, head restraint, and motion correction software that facilitate neural imaging in the awake brain with a fixed upright two-photon microscope. These approaches have proven to be applicable to a wide range of brain regions and should help further our understanding of how neuronal population activity within the brain's microcircuitry is connected to animal behavior.

A MATLAB-based eye tracking control system using non-invasive helmet head restraint in the macaque.

Tracking eye position is vital for behavioral and neurophysiological investigations in systems and cognitive neuroscience. Infrared camera systems which are now available can be used for eye tracking without the need to surgically implant magnetic search coils. These systems are generally employed using rigid head fixation in monkeys, which maintains the eye in a constant position and facilitates eye tracking. We investigate the use of non-rigid head fixation using a helmet that constrains only general head orientation and allows some freedom of movement. We present a MATLAB software solution to gather and process eye position data, present visual stimuli, interact with various devices, provide experimenter feedback and store data for offline analysis. Our software solution achieves excellent timing performance due to the use of data streaming, instead of the traditionally employed data storage mode for processing analog eye position data. We present behavioral data from two monkeys, demonstrating that adequate performance levels can be achieved on a simple fixation paradigm and show how performance depends on parameters such as fixation window size. Our findings suggest that non-rigid head restraint can be employed for behavioral training and testing on a variety of gaze-dependent visual paradigms, reducing the need for rigid head restraint systems for some applications. While developed for macaque monkey, our system of course can work equally well for applications in human eye tracking where head constraint is undesirable.

Brainstem processing of vestibular sensory exafference: implications for motion sickness etiology.

The origin of the internal "sensory conflict" stimulus causing motion sickness has been debated for more than four decades. Recent studies show a subclass of neurons in the vestibular nuclei and deep cerebellar nuclei that respond preferentially to passive head movements. During active movement, the semicircular canal and otolith input ("reafference") to these neurons are canceled by a mechanism comparing the expected consequences of self-generated movement (estimated with an internal model-presumably located in the cerebellum) with the actual sensory feedback. The un-canceled component ("exafference") resulting from passive movement normally helps compensate for unexpected postural disturbances. Notably, the existence of such vestibular "sensory conflict" neurons had been postulated as early as 1982, but their existence and putative role in posture control and motion sickness have been long debated. Here, we review the development of "sensory conflict" theories in relation to recent evidence for brainstem and cerebellar reafference cancelation, and identify some open research questions. We propose that conditions producing persistent activity of these neurons, or their targets, stimulate nearby brainstem emetic centers-via an as yet unidentified mechanism. We discuss how such a mechanism is consistent with the notable difference in motion sickness susceptibility of drivers as opposed to passengers, human immunity to normal self-generated movement and why head restraint or lying horizontal confers relative immunity. Finally, we propose that fuller characterization of these mechanisms and their potential role in motion sickness could lead to more effective, scientifically based prevention and treatment for motion sickness.

Experimental support that ocular tremor in Parkinson's disease does not originate from head movement.

Our recent report of ocular tremor in Parkinson's disease (PD) has raised considerable controversy as to the origin of the tremor. Using an infrared based eye tracker and a magnetic head tracker, we reported that ocular tremor was recordable in PD subjects with no apparent head tremor. However, other investigators suggest that the ocular tremor may represent either transmitted appendicular tremor or subclinical head tremor inducing the vestibulo-ocular reflex (VOR). The present study aimed to further investigate the origin of ocular tremor in PD. Eye movements were recorded in 8 PD subjects both head free, and with full head restraint by means of a head holding device and a dental impression bite plate. Head movements were recorded independently using both a high sensitivity tri-axial accelerometer and a magnetic tracking system, each synchronized to the eye tracker. Ocular tremor was observed in all 8 PD subjects and was not influenced by head free and head fixed conditions. Both magnetic tracking and accelerometer recordings supported that the ocular tremor was fully independent of head position. The present study findings support our initial findings that ocular tremor is a fundamental feature of PD unrelated to head movements. Although the utility of ocular tremor for diagnostic purposes requires validation, current findings in large cohorts of PD subjects suggest its potential as a reliable clinical biomarker.