Journal articles: 'Body accelerations'

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Picu, Mihaela. "A Study of Vertical Vibration Transmissibility by the Human Body." Applied Mechanics and Materials 325-326 (June 2013): 152–57. http://dx.doi.org/10.4028/www.scientific.net/amm.325-326.152.

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The transmission of longitudinal vibration (generated by the vibrating platform Brüel & Kjær 4827) in the whole body of ten subjects was investigated. Altogether 200 individual tests were made. Vibration was measured with 356A16 PCB Piezotronics triaxial accelerometers fixed to the toes, ankles, lumbar, cervical, fingers, elbow and shoulder. Vibrations were analyzed with a multiple acquisition vibrations system NetdB. Data were processed using dBFA Suite. Vibration time was 1min and frequency range was between 10-40Hz, because the low frequencies are the resonance frequencies for the human body. Body vibration transmissibility was determined by the ratio of root mean square acceleration signal from accelerometer by the root mean square of acceleration signal from the vibrating platform. It was found that the accelerations at the lumbar level are more attenuated than the accelerations at the ankle level.

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Thandiackal, Robin, Carl H. White, Hilary Bart-Smith, and George V. Lauder. "Tuna robotics: hydrodynamics of rapid linear accelerations." Proceedings of the Royal Society B: Biological Sciences 288, no. 1945 (2021): 20202726. http://dx.doi.org/10.1098/rspb.2020.2726.

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Fish routinely accelerate during locomotor manoeuvres, yet little is known about the dynamics of acceleration performance. Thunniform fish use their lunate caudal fin to generate lift-based thrust during steady swimming, but the lift is limited during acceleration from rest because required oncoming flows are slow. To investigate what other thrust-generating mechanisms occur during this behaviour, we used the robotic system termed Tunabot Flex, which is a research platform featuring yellowfin tuna-inspired body and tail profiles. We generated linear accelerations from rest of various magnitudes (maximum acceleration of 3.22 m s − 2 at 11.6 Hz tail beat frequency) and recorded instantaneous electrical power consumption. Using particle image velocimetry data, we quantified body kinematics and flow patterns to then compute surface pressures, thrust forces and mechanical power output along the body through time. We found that the head generates net drag and that the posterior body generates significant thrust, which reveals an additional propulsion mechanism to the lift-based caudal fin in this thunniform swimmer during linear accelerations from rest. Studying fish acceleration performance with an experimental platform capable of simultaneously measuring electrical power consumption, kinematics, fluid flow and mechanical power output provides a new opportunity to understand unsteady locomotor behaviours in both fishes and bioinspired aquatic robotic systems.

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Evans, A. L., G. Duncan, and W. Gilchrist. "Recording accelerations in body movements." Medical & Biological Engineering & Computing 29, no. 1 (1991): 102–4. http://dx.doi.org/10.1007/bf02446305.

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Savitsky, Daniel. "Direct Measure of Rigid Body Accelerations for Wave Impact of a Planing Hull." Journal of Ship Production and Design 32, no. 04 (2016): 235–44. http://dx.doi.org/10.5957/jspd.2016.32.4.235.

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Measurements of accelerations during wave impact of a planing hull are usually contaminated by nonhydrodynamic disturbances inherent in full-scale tests and by vibrations induced by the test model and towing carriage in towing tank tests. As a consequence, researchers have resorted to the use of electronic filters to extract rigid body hydrodynamic impact accelerations. This article first calculates the rigid body impact acceleration time histories of 2dimensional deadrise wedges impacting on a level water surface as a function of initial contact velocity, deadrise angle, and unit drop weight. It also calculates the spectral content of these time histories. It then demonstrates how the time histories, time to peak, and spectral content of these 2D wedges are distorted by the use of standard "one-way" electronic filters when processing the data. In a sense, this section of the article can be taken as a simple tutorial on the impact process. The Davidson Laboratory suggests and demonstrates the use of a rigid "free-running" model that is not rigidly connected to the towing carriage and is thus devoid of carriage-induced disturbances. This obviates the use of filters in processing the recorded data. Hence, the directly measured impact accelerations are thus rigid body hydrodynamic accelerations. These are compared with measurements made with the model rigidly attached to the carriage to demonstrate its effect on contaminating the recorded hydrodynamic signal. It is recommended that other towing tanks consider the use of this or other "free-model" test procedures to identify the possible contamination of the recorded acceleration time histories introduced by their carriage and model disturbances. It is also recommended that for those full-scale tests, where the "Standard G" method of data reduction has been applied, that a model be built and tested using the "free-model" test procedure suggested in this article. This will compare the derived rigid body accelerations with the true hydrodynamic impact accelerations as obtained in these free-model tests.

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Buckley, Christopher, Brook Galna, Lynn Rochester, and Claudia Mazzà. "Attenuation of Upper Body Accelerations during Gait: Piloting an Innovative Assessment Tool for Parkinson’s Disease." BioMed Research International 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/865873.

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The objective of the current investigation was to explore whether upper body accelerations obtained during gait provide sensitive measures of postural control in people with Parkinson’s disease (PD). Thirteen people with PD (70±11years) and nineteen age-matched controls (70±7years) walked continuously for two minutes while wearing three inertial sensors located on their lower back (L5), shoulder level (C7), and head. Magnitude (root mean square (RMS)), attenuation (attenuation coefficient), and smoothness (Harmonic ratios, HR) of the accelerations were calculated. People with PD demonstrated greater RMS, particularly in the mediolateral direction, but similar harmonic ratio of head accelerations compared to controls. In addition, they did not attenuate accelerations through the trunk and neck as well as control participants. Our findings indicate that measuring upper body movement provides unique information regarding postural control in PD and that poor attenuation of acceleration from the pelvis to the head contributes to impaired head control. This information is simple to measure and appears to be sensitive to PD and, consequently, is proposed to benefit researchers and clinicians.

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Martínez-Llop, Pablo Garrido, Juan de Dios Sanz Bobi, Álvaro Solano Jiménez, and Jorge Gutiérrez Sánchez. "Condition-Based Maintenance for Normal Behaviour Characterisation of Railway Car-Body Acceleration Applying Neural Networks." Sustainability 13, no. 21 (2021): 12265. http://dx.doi.org/10.3390/su132112265.

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Recently, passenger comfort and user experience are becoming increasingly relevant for the railway operators and, therefore, for railway manufacturers as well. The main reason for this to happen is that comfort is a clear differential value considered by passengers as final customers. Passengers’ comfort is directly related to the accelerations received through the car-body of the train. For this reason, suspension and damping components must be maintained in perfect condition, assuring high levels of comfort quality. An early detection of any potential failure in these systems derives in a better maintenance inspections’ planification and in a more sustainable approach to the whole train maintenance strategy. In this paper, an optimized model based on neural networks is trained in order to predict lateral car-body accelerations. Comparing these predictions to the values measured on the train, a normal characterisation of the lateral dynamic behaviour can be determined. Any deviation from this normal characterisation will imply a comfort loss or a potential degradation of the suspension and damping components. This model has been trained with a dataset from a specific train unit, containing variables recorded every second during the year 2017, including lateral and vertical car-body accelerations, among others. A minimum average error of 0.034 m/s2 is obtained in the prediction of lateral car-body accelerations. This means that the average error is approximately 2.27% of the typical maximum estimated values for accelerations in vehicle body reflected in the EN14363 for the passenger coaches (1.5 m/s2). Thus, a successful model is achieved. In addition, the model is evaluated based on a real situation in which a passenger noticed a lack of comfort, achieving excellent results in the detection of atypical accelerations. Therefore, as it is possible to measure acceleration deviations from the standard behaviour causing lack of comfort in passengers, an alert can be sent to the operator or the maintainer for a non-programmed intervention at depot (predictive maintenance) or on board (prescriptive maintenance). As a result, a condition-based maintenance (CBM) methodology is proposed to avoid comfort degradation that could end in passenger complaints or speed limitation due to safety reasons for excessive acceleration. This methodology highlights a sustainable maintenance concept and an energy efficiency strategy.

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Waddington, G., T. Dickson, S. Trathen, and R. Adams. "Walking for fitness: is it enough to maintain both heart and bone health?" Australian Journal of Primary Health 17, no. 1 (2011): 86. http://dx.doi.org/10.1071/py10035.

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Exercising at levels of whole body accelerations exceeding 3.6 g has been shown to have positive effects on cardiovascular fitness, bone density and balance. This pilot research project evaluated the whole body accelerations and cardiovascular challenge provided by selected walks in the Canberra region of Australia to determine if walks could be ranked according to potential level of impact on both cardiovascular fitness and bone health. Nine participants, who described themselves as walking at least 3 km, three times per week, wore a data logging device recording heart rate, acceleration and GPS position while walking three outdoor tracks: (1) the running track of an athletics stadium; (2) on a hill climb path through bushland; and (3) on a route through suburban streets. There was a significant difference (P < 0.05) for heart rate, distribution of whole body accelerations and average walking speed between track 2 and tracks 1 and 3. There was a significant difference for heart rate, distribution of whole body accelerations and average walking speed between the walks. The running track and the suburban walk provide a moderate exercise challenge, with the hill climb walk providing progressively greater vertical height challenge, resulting in an increased cardiovascular exercise challenge. No participant effectively exceeded the threshold for achieving a positive impact on bone density (100 or more accelerations/day >3.6 g) on track 1, and only two of the nine participants intermittently achieved this threshold on tracks 2 and 3.

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Reinker, Lukas, Dominic Bläsing, Rudolf Bierl, Sabina Ulbricht, and Sebastian Dendorfer. "Correlation of Acceleration Curves in Gravitational Direction for Different Body Segments during High-Impact Jumping Exercises." Sensors 23, no. 4 (2023): 2276. http://dx.doi.org/10.3390/s23042276.

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Osteoporosis is a common disease of old age. However, in many cases, it can be very well prevented and counteracted with physical activity, especially high-impact exercises. Wearables have the potential to provide data that can help with continuous monitoring of patients during therapy phases or preventive exercise programs in everyday life. This study aimed to determine the accuracy and reliability of measured acceleration data at different body positions compared to accelerations at the pelvis during different jumping exercises. Accelerations at the hips have been investigated in previous studies with regard to osteoporosis prevention. Data were collected using an IMU-based motion capture system (Xsens) consisting of 17 sensors. Forty-nine subjects were included in this study. The analysis shows the correlation between impacts and the corresponding drop height, which are dependent on the respective exercise. Very high correlations (0.83–0.94) were found between accelerations at the pelvis and the other measured segments at the upper body. The foot sensors provided very weak correlations (0.20–0.27). Accelerations measured at the pelvis during jumping exercises can be tracked very well on the upper body and upper extremities, including locations where smart devices are typically worn, which gives possibilities for remote and continuous monitoring of programs.

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Arruda, Ademir F. S., Christopher Carling, Vinicius Zanetti, Marcelo S. Aoki, Aaron J. Coutts, and Alexandre Moreira. "Effects of a Very Congested Match Schedule on Body-Load Impacts, Accelerations, and Running Measures in Youth Soccer Players." International Journal of Sports Physiology and Performance 10, no. 2 (2015): 248–52. http://dx.doi.org/10.1123/ijspp.2014-0148.

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Purpose:To analyze the effects of a very congested match schedule on the total distance (TD) covered, high-intensity-running (HIR) distance, and frequency of accelerations and body-load impacts (BLIs) performed in a team of under-15 soccer players (N = 10; 15.1 ± 0.2 y, 171.8 ± 4.7 cm, 61 ± 6.0 kg) during an international youth competition.Methods:Using global positioning systems, player performances were repeatedly monitored in 5 matches performed over 3 successive days.Results:Significant differences were observed between matches (P < .05) for the frequency of accelerations per minute, BLIs, and BLIs per minute. No differences were observed for the TD covered, TD run per minute, number of high-intensity runs, distance covered in HIR, per-minute peak running speed attained, or frequency of accelerations. The frequency of accelerations per minute decreased across the competition while BLIs were higher during the final than in all other matches.Conclusions:These results suggest that BLIs and acceleration might be used as an alternative means to represent the external load during congested match schedules rather than measures related to running speed or distance covered.

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Zhao, Jing-Shan, Song-Tao Wei, and Xiao-Cheng Sun. "Computational Dynamics of Multi-Rigid-Body System in Screw Coordinate." Applied Sciences 13, no. 10 (2023): 6341. http://dx.doi.org/10.3390/app13106341.

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This paper investigates the kinematics and dynamics of multi-rigid-body systems in screw form. The Newton–Euler dynamics equations are established in screw coordinates. All forces and torques of the multi-rigid-body system can be solved straightforwardly since they are explicit in the form of screw coordinates. The displacement and acceleration are unified in matrix form, which associates the kinematics and dynamics with variable of velocity. A one-step numerical algorithm only is needed to solve the displacements and accelerations. As a result, all absolute displacements, velocities, and accelerations are directly obtained by one kinematic equation. The kinematics and dynamics of Gough–Stewart platform validate this the method. In this paper, the kinematics and dynamics are carried out with the example of a Gough–Stewart platform, which represents the most complex multi-rigid-body system, to verify the computational dynamics method. The proposed algorithm is also fit for the kinematics and dynamics modeling of other multi-rigid-body systems.

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Bakker, Romy S., Roel H. A. Weijer, Robert J. van Beers, Luc P. J. Selen, and W. Pieter Medendorp. "Decisions in motion: passive body acceleration modulates hand choice." Journal of Neurophysiology 117, no. 6 (2017): 2250–61. http://dx.doi.org/10.1152/jn.00022.2017.

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In everyday life, we frequently have to decide which hand to use for a certain action. It has been suggested that for this decision the brain calculates expected costs based on action values, such as expected biomechanical costs, expected success rate, handedness, and skillfulness. Although these conclusions were based on experiments in stationary subjects, we often act while the body is in motion. We investigated how hand choice is affected by passive body motion, which directly affects the biomechanical costs of the arm movement due to its inertia. With the use of a linear motion platform, 12 right-handed subjects were sinusoidally translated (0.625 and 0.5 Hz). At 8 possible motion phases, they had to reach, using either their left or right hand, to a target presented at 1 of 11 possible locations. We predicted hand choice by calculating the expected biomechanical costs under different assumptions about the future acceleration involved in these computations, being the forthcoming acceleration during the reach, the instantaneous acceleration at target onset, or zero acceleration as if the body were stationary. Although hand choice was generally biased to use of the dominant hand, it also modulated sinusoidally with the motion, with the amplitude of the bias depending on the motion’s peak acceleration. The phase of hand choice modulation was consistent with the cost model that took the instantaneous acceleration signal at target onset. This suggests that the brain relies on the bottom-up acceleration signals, and not on predictions about future accelerations, when deciding on hand choice during passive whole body motion. NEW & NOTEWORTHY Decisions of hand choice are a fundamental aspect of human behavior. Whereas these decisions are typically studied in stationary subjects, this study examines hand choice while subjects are in motion. We show that accelerations of the body, which differentially modulate the biomechanical costs of left and right hand movements, are also taken into account when deciding which hand to use for a reach, possibly based on bottom-up processing of the otolith signal.

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Kavanagh, Justin J., Steven Morrison, and Rod S. Barrett. "Lumbar and cervical erector spinae fatigue elicit compensatory postural responses to assist in maintaining head stability during walking." Journal of Applied Physiology 101, no. 4 (2006): 1118–26. http://dx.doi.org/10.1152/japplphysiol.00165.2006.

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The purpose of this study was to examine how inducing fatigue of the 1) lumbar erector spinae and 2) cervical erector spinae (CES) muscles affected the ability to maintain head stability during walking. Triaxial accelerometers were attached to the head, upper trunk, and lower trunk to measure accelerations in the vertical, anterior-posterior, and mediolateral directions during walking. Using three accelerometers enabled two adjacent upper body segments to be defined: the neck segment and trunk segment. A transfer function was applied to root mean square acceleration, peak power, and harmonic data derived from spectral analysis of accelerations to quantify segmental gain. The structure of upper body accelerations were examined using measures of signal regularity and smoothness. The main findings were that head stability was only affected in the anterior-posterior direction, as accelerations of the head were less regular following CES fatigue. Furthermore, following CES fatigue, the central nervous system altered the attenuation properties of the trunk segment in the anterior-posterior direction, presumably to enhance head stability. Following lumbar erector spinae fatigue, the trunk segment had greater gain and increased regularity and smoothness of accelerations in the mediolateral direction. Overall, the results of this study suggest that erector spinae fatigue differentially altered segmental attenuation during walking, according to the level of the upper body that was fatigued and the direction that oscillations were attenuated. A compensatory postural response was not only elicited in the sagittal plane, where greater segmental attenuation occurred, but also in the frontal plane, where greater segmental gain occurred.

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Rossborough, Jackson, Angeles Salles, Laura Stidsholt, Peter T. Madsen, Cynthia F. Moss, and Larry F. Hoffman. "Inflight head stabilization associated with wingbeat cycle and sonar emissions in the lingual echolocating Egyptian fruit bat, Rousettus aegyptiacus." Journal of Comparative Physiology A 207, no. 6 (2021): 757–72. https://doi.org/10.5281/zenodo.13432212.

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(Uploaded by Plazi for the Bat Literature Project) Sensory processing of environmental stimuli is challenged by head movements that perturb sensorimotor coordinate frames directing behaviors. In the case of visually guided behaviors, visual gaze stabilization results from the integrated activity of the vestibuloocular reflex and motor efference copy originating within circuits driving locomotor behavior. In the present investigation, it was hypothesized that head stabilization is broadly implemented in echolocating bats during sustained flight, and is temporally associated with emitted sonar signals which would optimize acoustic gaze. Predictions from these hypotheses were evaluated by measuring head and body kinematics with motion sensors attached to the head and body of free-flying Egyptian fruit bats. These devices were integrated with ultrasonic microphones to record sonar emissions and elucidate the temporal association with periods of head stabilization. Head accelerations in the Earth-vertical axis were asymmetric with respect to wing downstroke and upstroke relative to body accelerations. This indicated that inflight head and body accelerations were uncoupled, outcomes consistent with the mechanisms that limit vertical head acceleration during wing downstroke. Furthermore, sonar emissions during stable flight occurred most often during wing downstroke and head stabilization, supporting the conclusion that head stabilization behavior optimized sonar gaze and environmental interrogation via echolocation.

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Rossborough, Jackson, Angeles Salles, Laura Stidsholt, Peter T. Madsen, Cynthia F. Moss, and Larry F. Hoffman. "Inflight head stabilization associated with wingbeat cycle and sonar emissions in the lingual echolocating Egyptian fruit bat, Rousettus aegyptiacus." Journal of Comparative Physiology A 207, no. 6 (2021): 757–72. https://doi.org/10.5281/zenodo.13432212.

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(Uploaded by Plazi for the Bat Literature Project) Sensory processing of environmental stimuli is challenged by head movements that perturb sensorimotor coordinate frames directing behaviors. In the case of visually guided behaviors, visual gaze stabilization results from the integrated activity of the vestibuloocular reflex and motor efference copy originating within circuits driving locomotor behavior. In the present investigation, it was hypothesized that head stabilization is broadly implemented in echolocating bats during sustained flight, and is temporally associated with emitted sonar signals which would optimize acoustic gaze. Predictions from these hypotheses were evaluated by measuring head and body kinematics with motion sensors attached to the head and body of free-flying Egyptian fruit bats. These devices were integrated with ultrasonic microphones to record sonar emissions and elucidate the temporal association with periods of head stabilization. Head accelerations in the Earth-vertical axis were asymmetric with respect to wing downstroke and upstroke relative to body accelerations. This indicated that inflight head and body accelerations were uncoupled, outcomes consistent with the mechanisms that limit vertical head acceleration during wing downstroke. Furthermore, sonar emissions during stable flight occurred most often during wing downstroke and head stabilization, supporting the conclusion that head stabilization behavior optimized sonar gaze and environmental interrogation via echolocation.

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Rossborough, Jackson, Angeles Salles, Laura Stidsholt, Peter T. Madsen, Cynthia F. Moss, and Larry F. Hoffman. "Inflight head stabilization associated with wingbeat cycle and sonar emissions in the lingual echolocating Egyptian fruit bat, Rousettus aegyptiacus." Journal of Comparative Physiology A 207, no. 6 (2021): 757–72. https://doi.org/10.5281/zenodo.13432212.

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(Uploaded by Plazi for the Bat Literature Project) Sensory processing of environmental stimuli is challenged by head movements that perturb sensorimotor coordinate frames directing behaviors. In the case of visually guided behaviors, visual gaze stabilization results from the integrated activity of the vestibuloocular reflex and motor efference copy originating within circuits driving locomotor behavior. In the present investigation, it was hypothesized that head stabilization is broadly implemented in echolocating bats during sustained flight, and is temporally associated with emitted sonar signals which would optimize acoustic gaze. Predictions from these hypotheses were evaluated by measuring head and body kinematics with motion sensors attached to the head and body of free-flying Egyptian fruit bats. These devices were integrated with ultrasonic microphones to record sonar emissions and elucidate the temporal association with periods of head stabilization. Head accelerations in the Earth-vertical axis were asymmetric with respect to wing downstroke and upstroke relative to body accelerations. This indicated that inflight head and body accelerations were uncoupled, outcomes consistent with the mechanisms that limit vertical head acceleration during wing downstroke. Furthermore, sonar emissions during stable flight occurred most often during wing downstroke and head stabilization, supporting the conclusion that head stabilization behavior optimized sonar gaze and environmental interrogation via echolocation.

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Rossborough, Jackson, Angeles Salles, Laura Stidsholt, Peter T. Madsen, Cynthia F. Moss, and Larry F. Hoffman. "Inflight head stabilization associated with wingbeat cycle and sonar emissions in the lingual echolocating Egyptian fruit bat, Rousettus aegyptiacus." Journal of Comparative Physiology A 207, no. 6 (2021): 757–72. https://doi.org/10.5281/zenodo.13432212.

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(Uploaded by Plazi for the Bat Literature Project) Sensory processing of environmental stimuli is challenged by head movements that perturb sensorimotor coordinate frames directing behaviors. In the case of visually guided behaviors, visual gaze stabilization results from the integrated activity of the vestibuloocular reflex and motor efference copy originating within circuits driving locomotor behavior. In the present investigation, it was hypothesized that head stabilization is broadly implemented in echolocating bats during sustained flight, and is temporally associated with emitted sonar signals which would optimize acoustic gaze. Predictions from these hypotheses were evaluated by measuring head and body kinematics with motion sensors attached to the head and body of free-flying Egyptian fruit bats. These devices were integrated with ultrasonic microphones to record sonar emissions and elucidate the temporal association with periods of head stabilization. Head accelerations in the Earth-vertical axis were asymmetric with respect to wing downstroke and upstroke relative to body accelerations. This indicated that inflight head and body accelerations were uncoupled, outcomes consistent with the mechanisms that limit vertical head acceleration during wing downstroke. Furthermore, sonar emissions during stable flight occurred most often during wing downstroke and head stabilization, supporting the conclusion that head stabilization behavior optimized sonar gaze and environmental interrogation via echolocation.

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Kanchwala, Husain. "Vehicle suspension model development using test track measurements." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 234, no. 5 (2019): 1442–59. http://dx.doi.org/10.1177/0954407019867504.

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Detailed suspension modeling is a prerequisite for accurate vehicle dynamics simulation. Quarter car models are widely used in the literature, but they are simple and do not capture all dynamic effects. On the other hand, full car models are computationally complex and not available to the designer at initial stage of vehicle development. A test track data based methodology to develop a Laplace domain reduced order suspension model of intermediate complexity between a full car and a quarter car model is presented in this paper. A prototype vehicle is driven on sinusoidal tracks and vertical accelerations of wheel axles and suspension to body attachment points are measured. Using this acceleration data, a transfer function model is fitted to predict the body points accelerations in response to measured wheel–axle accelerations. This model is further extended to incorporate an unsprung mass model and retain suspension properties as free parameters to enable quick parametric studies without repeated field testing. A discussion is given of aspects of the model that match experiments, as well as possible sources of observed mismatch. Finally, two potential applications are given to study the effect of suspension and unsprung mass model properties on body point responses.

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Ekdahl, Mitchell, Sophia Ulman, and Lauren Butler. "Relationship of Knee Abduction Moment to Trunk and Lower Extremity Segment Acceleration during Sport-Specific Movements." Sensors 24, no. 5 (2024): 1454. http://dx.doi.org/10.3390/s24051454.

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The knee abduction moment (KAM) has been identified as a significant predictor of anterior cruciate ligament (ACL) injury risk; however, the cost and time demands associated with collecting three-dimensional (3D) kinetic data have prompted the need for alternative solutions. Wearable inertial measurement units (IMUs) have been explored as a potential solution for quantitative on-field assessment of injury risk. Most previous work has focused on angular velocity data, which are highly susceptible to bias and noise relative to acceleration data. The purpose of this pilot study was to assess the relationship between KAM and body segment acceleration during sport-specific movements. Three functional tasks were selected to analyze peak KAM using optical motion capture and force plates as well as peak triaxial segment accelerations using IMUs. Moderate correlations with peak KAM were observed for peak shank acceleration during single-leg hop; peak trunk, thigh, and shank accelerations during a deceleration task; and peak trunk, pelvis, and shank accelerations during a 45° cut. These findings provide preliminary support for the use of wearable IMUs to identify peak KAM during athletic tasks.

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Karp, Alan H. "Speeding up N-body Calculations on Machines without Hardware Square Root." Scientific Programming 1, no. 2 (1992): 133–40. http://dx.doi.org/10.1155/1992/974623.

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The most time consuming part of an N-body simulation is computing the components of the accelerations of the particles. On most machines the slowest part of computing the acceleration is in evaluating r-3/2, which is especially true on machines that do the square root in software. This note shows how to cut the time for this part of the calculation by a factor of 3 or more using standard Fortran.

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Stevens, Tom G. A., Cornelis J. de Ruiter, Cas van Niel, Roxanne van de Rhee, Peter J. Beek, and Geert J. P. Savelsbergh. "Measuring Acceleration and Deceleration in Soccer-Specific Movements Using a Local Position Measurement (LPM) System." International Journal of Sports Physiology and Performance 9, no. 3 (2014): 446–56. http://dx.doi.org/10.1123/ijspp.2013-0340.

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Purpose:A local position measurement (LPM) system can accurately track the distance covered and the average speed of whole-body movements. However, for the quantification of a soccer player’s workload, accelerations rather than positions or speeds are essential. The main purpose of the current study was therefore to determine the accuracy of LPM in measuring average and peak accelerations for a broad range of (maximal) soccerspecific movements.Methods:Twelve male amateur soccer players performed 8 movements (categorized in straight runs and runs involving a sudden change in direction of 90° or 180°) at 3 intensities (jog, submaximal, maximal). Position-related parameters recorded with LPM were compared with Vicon motion-analysis data sampled at 100 Hz. The differences between LPM and Vicon data were expressed as percentage of the Vicon data.Results:LPM provided reasonably accurate measurements for distance, average speed, and peak speed (differences within 2% across all movements and intensities). For average acceleration and deceleration, absolute bias and 95% limits of agreement were 0.01 ± 0.36 m/s2 and 0.02 ± 0.38 m/s2, respectively. On average, peak acceleration was overestimated (0.48 ± 1.27 m/s2) by LPM, while peak deceleration was underestimated (0.32 ± 1.17 m/s2).Conclusion:LPM accuracy appears acceptable for most measurements of average acceleration and deceleration, but for peak acceleration and deceleration accuracy is limited. However, when these error margins are kept in mind, the system may be used in practice for quantifying average accelerations and parameters such as summed accelerations or time spent in acceleration zones.

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Cation, Sarah, Michele Oliver, Robert Joel Jack, James P. Dickey, and Natasha Lee Shee. "Whole-Body Vibration Sensor Calibration Using a Six-Degree of Freedom Robot." Advances in Acoustics and Vibration 2011 (May 12, 2011): 1–7. http://dx.doi.org/10.1155/2011/276898.

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Exposure to whole-body vibration (WBV) is associated with a wide variety of health disorders and as a result WBV levels are frequently assessed. Literature outlining WBV accelerations rarely address the calibration techniques and procedures used for WBV sensors to any depth, nor are any detailed information provided regarding such procedures or sensor calibration ranges. The purpose of this paper is to describe a calibration method for a 6 DOF transducer using a hexapod robot. Also described is a separate motion capture technique used to verify the calibration for acceleration values obtained which were outside the robot calibration range in order to include an acceptable calibration range for WBV environments. The sensor calibrated in this study used linear (Y=mX) calibration equations resulting in r2 values greater than 0.97 for maximum and minimum acceleration amplitudes of up to ±8 m/s2 and maximum and minimum velocity amplitudes up to ±100°/s. The motion capture technique verified that the translational calibrations held for accelerations up to ±4 g. Thus, the calibration procedures were shown to calibrate the sensor through the expected range for 6-DOF WBV field measurements for off-road vehicles even when subjected to shocks as a result of high speed travel over rough terrain.

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Condurache, Daniel, Mihail Cojocari, and Ionuţ Popa. "Hypercomplex Quaternions and Higher-Order Analysis of Spatial Kinematic Chains." BULETINUL INSTITUTULUI POLITEHNIC DIN IAȘI. Secția Matematica. Mecanică Teoretică. Fizică 69, no. 1-4 (2023): 21–34. http://dx.doi.org/10.2478/bipmf-2023-0002.

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Abstract This paper introduces a novel computational method for analyzing the higher-order acceleration field of spatial kinematics chains. The method is based on vector and quaternionic calculus, as well as dual and multidual algebra. A closed-form coordinate-free solution generated by the morphism between the Lie group of rigid body displacements and the unit multidual quaternions is presented. Presented solution is used for higher-order kinematics investigation of lower-pair serial chains. Additionally, a general method for studying the vector field of arbitrary higher-order accelerations is discribed. The method utilizes the “automatic differentiation” feature of multidual and hyper-multidual functions to obtain the higher-order derivative of a rigid body pose without need in further differentiation of the body pose regarding time. Also is proved that all information regarding the properties of the distribution of higher-order accelerations is contained in the specified unit hyper-multidual quaternion.

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Gellner, Ryan A., Eamon T. Campolettano, Eric P. Smith, and Steven Rowson. "Are specific players more likely to be involved in high-magnitude head impacts in youth football?" Journal of Neurosurgery: Pediatrics 24, no. 1 (2019): 47–53. http://dx.doi.org/10.3171/2019.2.peds18176.

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OBJECTIVEYouth football attracts approximately 3.5 million participants every year, but concern has recently arisen about the long-term effects of experiencing repetitive head accelerations from a young age due to participation in football. The objective of this study was to quantify total involvement in high-magnitude impacts among individual players in youth football practices. The authors explored the relationship between the total number of high-magnitude accelerations in which players were involved (experienced either by themselves or by other players) during practices and the number of high-magnitude accelerations players experienced.METHODSA local cohort of 94 youth football players (mean age 11.9 ± 1.5, mean body mass 50.3 ± 16.4 kg) from 4 different teams were recruited and outfitted with helmet-mounted accelerometer arrays. The teams were followed for one season each for a total of 128 sessions (practices, games, and scrimmages). All players involved in high-magnitude (greater than 40g) head accelerations were subsequently identified through analysis of practice film.RESULTSPlayers who experienced more high-magnitude accelerations were more likely to be involved in impacts associated with high-magnitude accelerations in other players. A small subset of 6 players (6%) were collectively involved in 230 (53%) high-magnitude impacts during practice, were involved in but did not experience a high-magnitude acceleration 78 times (21% of the 370 one-sided high-magnitude impacts), and experienced 152 (30%) of the 502 high-magnitude accelerations measured. Quarterbacks/running backs/linebackers were involved in the greatest number of high-magnitude impacts in practice and experienced the greatest number of high-magnitude accelerations. Which team a player was on was an important factor, as one team showed much greater head impact exposure than all others.CONCLUSIONSThis study showed that targeting the most impact-prone players for individualized interventions could reduce high-magnitude acceleration exposure for entire teams. These data will help to further quantify elevated head acceleration exposure and enable data-driven interventions that modify exposure for individual players and entire teams.

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Lucas-Cuevas, Angel G., Pedro Pérez-Soriano, Michael Bush, et al. "Effects of Different Backpack Loads in Acceleration Transmission during Recreational Distance Walking." Journal of Human Kinetics 37, no. 1 (2013): 81–89. http://dx.doi.org/10.2478/hukin-2013-0028.

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It is well established nowadays the benefits that physical activity can have on the health of individuals. Walking is considered a fundamental method of movement and using a backpack is a common and economical manner of carrying load weight. Nevertheless, the shock wave produced by the impact forces when carrying a backpack can have detrimental effects on health status. Therefore, the aim of this study was to investigate differences in the accelerations placed on males and females whilst carrying different loads when walking. Twenty nine sports science students (16 males and 13 females) participated in the study under 3 different conditions: no weight, 10% and 20% body weight (BW) added in a backpack. Accelerometers were attached to the right shank and the centre of the forehead. Results showed that males have lower accelerations than females both in the head (2.62 ± 0.43G compared to 2.83 + 0.47G) and shank (1.37 ± 0.14G compared to 1.52 ± 0.15G; p<0.01). Accelerations for males and females were consistent throughout each backpack condition (p>0.05). The body acts as a natural shock absorber, reducing the amount of force that transmits through the body between the foot (impact point) and head. Anthropometric and body mass distribution differences between males and females may result in women receiving greater impact acceleration compared to men when the same load is carried.

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Aubert, Jean-Thomas, and Christian Ribreau. "Contribution of Inertia on Venous Flow in the Lower Limb during Stationary Gait." Journal of Applied Biomechanics 20, no. 2 (2004): 115–28. http://dx.doi.org/10.1123/jab.20.2.115.

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Blood flows toward the heart through collapsible vessels, the veins. The equations of flow in collapsible tubes in motion show a strong dependence on body forces resulting from gravity and acceleration. This paper analyzes the contribution of body forces to venous blood flow during walking on level ground. It combines the biomechanics of gait and theory of collapsible tubes to point out that body forces due to gravity and limb acceleration cannot be overlooked when considering the determinants of venous blood flow during locomotion. The study involved the development of a kinematic model of the limb as a multi-pendulum arrangement in which the limb segments undergo angular displacements. Angular velocities and accelerations were determined and the body forces were calculated during various phases of the gait cycle. A vascular model of the leg's major venous system was also constructed, and the accelerations due to body and gravity forces were calculated in specific venous segments, using the data from the kinematic model. The results showed there were large, fast variations in the axial component (Gx–Mx) of the body forces in veins between the hip and the ankle. Acceleration peaks down to –2G were obtained at normal locomotion. At fast locomotion, a distal vein in the shank displayed values of (Gx–Mx)/G equal to –3.2. Given the down-to-up orientation of the x-axis, the axial component Mx was usually positive in the axial veins, and Mx could shift from positive to negative during the gait cycle in the popliteal vein and the dorsal venous arch.

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Mačužić Saveljić, S., B. Arsić, I. Saveljić, and J. Lukić. "In-vehicle comfort assessment during fore-and-aft random vibrations based on artificial neural networks (ANN)." IOP Conference Series: Materials Science and Engineering 1271, no. 1 (2022): 012021. http://dx.doi.org/10.1088/1757-899x/1271/1/012021.

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Abstract Driving comfort is one of the important factors for vehicle users. There is a lot of research related to comfort or discomfort in a vehicle but there is still no well-defined way to assess it accurately. In this paper, an assessment of vehicle comfort during fore-and-aft random vibrations was made based on measured and predicted r.m.s. acceleration values. Measured values of r.m.s. accelerations were obtained by laboratory testing while the predicted values of r.m.s. accelerations obtained based on the ANN (Artifical Neural Network) model. 20 male subjects participated in the study. Their different anthropometric characteristics of the body were taken into account. Based on the measured r.m.s. values of acceleration formed ANN model which has ability to predict r.m.s. acceleration values based on measured values. The obtained results showed high accuracy of the model.

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Blouin, Jean-Sébastien, Gunter P. Siegmund, and J. Timothy Inglis. "Interaction between acoustic startle and habituated neck postural responses in seated subjects." Journal of Applied Physiology 102, no. 4 (2007): 1574–86. http://dx.doi.org/10.1152/japplphysiol.00703.2006.

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Postural and startle responses rapidly habituate with repeated exposures to the same stimulus, and the first exposure to a seated forward acceleration elicits a startle response in the neck muscles. Our goal was to examine how the acoustic startle response is integrated with the habituated neck postural response elicited by forward accelerations of seated subjects. In experiment 1, 14 subjects underwent 11 sequential forward accelerations followed by 5 additional sled accelerations combined with a startling tone (124-dB sound pressure level) initiated 18 ms after sled acceleration onset. During the acceleration-only trials, changes consistent with habituation occurred in the root-mean-square amplitude of the neck muscles and in the peak amplitude of five head and torso kinematic variables. The subsequent addition of the startling tone restored the amplitude of the neck muscles and four of the five kinematic variables but shortened onset of muscle activity by 9–12 ms. These shortened onset times were further explored in experiment 2, wherein 16 subjects underwent 11 acceleration-only trials followed by 15 combined acceleration-tone trials with interstimulus delays of 0, 13, 18, 23, and 28 ms. Onset times shortened further for the 0- and 13-ms delays but did not lengthen for the 23- and 28-ms delays. These temporal and spatial changes in EMG can be explained by a summation of the excitatory drive converging at or before the neck muscle motoneurons. The present observations suggest that habituation to repeated sled accelerations involves extinguishing the startle response and tuning the postural response to the whole body disturbance.

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Chen, Xuechao, Qiang Huang, Zhangguo Yu, and Yuepin Lu. "Robust push recovery by whole-body dynamics control with extremal accelerations." Robotica 32, no. 3 (2013): 467–76. http://dx.doi.org/10.1017/s0263574713000829.

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SUMMARYThis paper presents a whole-body dynamics controller for robust push recovery on a force-controlled bipedal robot. Featherstone's spatial vector method is used to deduce dynamics formulas. We reveal a relationship between the accelerations of the floating base and the desired external forces needed for those accelerations. Introducing constraints on the desired external forces causes corresponding constraints on the accelerations. Quadratic programming is applied to find the extremal accelerations, which recover the robot from pushes as best as possible. A robustness criterion is proposed based on the linear inverted pendulum model to evaluate the performance of push recovery methods quantitatively. We evaluate four typical push recovery methods and the results show that our method is more robust than these. The effectiveness of the proposed method is demonstrated by push recovery in simulations.

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Kejonen, Pirjo, Kari Kauranen, Ahti Niinimaa, and Heikki Vanharanta. "Velocities and Accelerations of Body Parts during Standing: Association with Visual Information." Journal of Sport Rehabilitation 13, no. 1 (2004): 31–43. http://dx.doi.org/10.1123/jsr.13.1.31.

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Context:Balance evaluation and training are typically included in rehabilitation after sport injuries.Objective:To evaluate and compare the maximal velocities and accelerations of balancing movements during 2-leg stance with eyes open and closed. The effect of age on the measured values was also evaluated.Design:Cross-sectional study.Participants:100 healthy, randomly selected subjects (50 men, 50 women; age 31–80 years).Setting:Body-movement values were measured with the Mac Reflex motion-analysis system.Intervention:Subjects stood barefoot.Main Outcome Measures:ANOVAs were used to explain the body movements. The location of measurement, presence or absence of vision, and subjects’ age and gender were used as explanatory variables.Results:With eyes closed, all measured body parts had significantly higher maximal velocity and acceleration values than with eyes open. Age seemed to affect the acceleration values.Conclusion:Visual information was found to significantly influence movement values. Exercises should be done under various conditions to improve standing balance abilities.

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Roberts, Thomas J., and Jeffrey A. Scales. "Mechanical power output during running accelerations in wild turkeys." Journal of Experimental Biology 205, no. 10 (2002): 1485–94. http://dx.doi.org/10.1242/jeb.205.10.1485.

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SUMMARYWe tested the hypothesis that the hindlimb muscles of wild turkeys(Meleagris gallopavo) can produce maximal power during running accelerations. The mechanical power developed during single running steps was calculated from force-plate and high-speed video measurements as turkeys accelerated over a trackway. Steady-speed running steps and accelerations were compared to determine how turkeys alter their running mechanics from a low-power to a high-power gait. During maximal accelerations, turkeys eliminated two features of running mechanics that are characteristic of steady-speed running: (i) they produced purely propulsive horizontal ground reaction forces, with no braking forces, and (ii) they produced purely positive work during stance, with no decrease in the mechanical energy of the body during the step. The braking and propulsive forces ordinarily developed during steady-speed running are important for balance because they align the ground reaction force vector with the center of mass. Increases in acceleration in turkeys correlated with decreases in the angle of limb protraction at toe-down and increases in the angle of limb retraction at toe-off. These kinematic changes allow turkeys to maintain the alignment of the center of mass and ground reaction force vector during accelerations when large propulsive forces result in a forward-directed ground reaction force. During the highest accelerations, turkeys produced exclusively positive mechanical power. The measured power output during acceleration divided by the total hindlimb muscle mass yielded estimates of peak instantaneous power output in excess of 400 W kg-1 hindlimb muscle mass. This value exceeds estimates of peak instantaneous power output of turkey muscle fibers. The mean power developed during the entire stance phase increased from approximately zero during steady-speed runs to more than 150 W kg-1muscle during the highest accelerations. The high power outputs observed during accelerations suggest that elastic energy storage and recovery may redistribute muscle power during acceleration. Elastic mechanisms may expand the functional range of muscle contractile elements in running animals by allowing muscles to vary their mechanical function from force-producing struts during steady-speed running to power-producing motors during acceleration.

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Iriarte-Díaz, José, Daniel K. Riskin, David J. Willis, Kenneth S. Breuer, and Sharon M. Swartz. "Whole-body kinematics of a fruit bat reveal the influence of wing inertia on body accelerations." Journal of Experimental Biology 214, no. 9 (2011): 1546–53. https://doi.org/10.5281/zenodo.13450747.

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(Uploaded by Plazi for the Bat Literature Project) The center of mass (COM) of a flying animal accelerates through space because of aerodynamic and gravitational forces. For vertebrates, changes in the position of a landmark on the body have been widely used to estimate net aerodynamic forces. The flapping of relatively massive wings, however, might induce inertial forces that cause markers on the body to move independently of the COM, thus making them unreliable indicators of aerodynamic force. We used high-speed three-dimensional kinematics from wind tunnel flights of four lesser dog-faced fruit bats, Cynopterus brachyotis, at speeds ranging from 2.4 to 7.8ms–1 to construct a time-varying model of the mass distribution of the bats and to estimate changes in the position of their COM through time. We compared accelerations calculated by markers on the trunk with accelerations calculated from the estimated COM and we found significant inertial effects on both horizontal and vertical accelerations. We discuss the effect of these inertial accelerations on the long-held idea that, during slow flights, bats accelerate their COM forward during 'tip-reversal upstrokes', whereby the distal portion of the wing moves upward and backward with respect to still air. This idea has been supported by the observation that markers placed on the body accelerate forward during tip-reversal upstrokes. As in previously published studies, we observed that markers on the trunk accelerated forward during the tip-reversal upstrokes. When removing inertial effects, however, we found that the COM accelerated forward primarily during the downstroke. These results highlight the crucial importance of the incorporation of inertial effects of wing motion in the analysis of flapping flight.

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38

Iriarte-Díaz, José, Daniel K. Riskin, David J. Willis, Kenneth S. Breuer, and Sharon M. Swartz. "Whole-body kinematics of a fruit bat reveal the influence of wing inertia on body accelerations." Journal of Experimental Biology 214, no. 9 (2011): 1546–53. https://doi.org/10.5281/zenodo.13450747.

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(Uploaded by Plazi for the Bat Literature Project) The center of mass (COM) of a flying animal accelerates through space because of aerodynamic and gravitational forces. For vertebrates, changes in the position of a landmark on the body have been widely used to estimate net aerodynamic forces. The flapping of relatively massive wings, however, might induce inertial forces that cause markers on the body to move independently of the COM, thus making them unreliable indicators of aerodynamic force. We used high-speed three-dimensional kinematics from wind tunnel flights of four lesser dog-faced fruit bats, Cynopterus brachyotis, at speeds ranging from 2.4 to 7.8ms–1 to construct a time-varying model of the mass distribution of the bats and to estimate changes in the position of their COM through time. We compared accelerations calculated by markers on the trunk with accelerations calculated from the estimated COM and we found significant inertial effects on both horizontal and vertical accelerations. We discuss the effect of these inertial accelerations on the long-held idea that, during slow flights, bats accelerate their COM forward during 'tip-reversal upstrokes', whereby the distal portion of the wing moves upward and backward with respect to still air. This idea has been supported by the observation that markers placed on the body accelerate forward during tip-reversal upstrokes. As in previously published studies, we observed that markers on the trunk accelerated forward during the tip-reversal upstrokes. When removing inertial effects, however, we found that the COM accelerated forward primarily during the downstroke. These results highlight the crucial importance of the incorporation of inertial effects of wing motion in the analysis of flapping flight.

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39

Iriarte-Díaz, José, Daniel K. Riskin, David J. Willis, Kenneth S. Breuer, and Sharon M. Swartz. "Whole-body kinematics of a fruit bat reveal the influence of wing inertia on body accelerations." Journal of Experimental Biology 214, no. 9 (2011): 1546–53. https://doi.org/10.5281/zenodo.13450747.

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(Uploaded by Plazi for the Bat Literature Project) The center of mass (COM) of a flying animal accelerates through space because of aerodynamic and gravitational forces. For vertebrates, changes in the position of a landmark on the body have been widely used to estimate net aerodynamic forces. The flapping of relatively massive wings, however, might induce inertial forces that cause markers on the body to move independently of the COM, thus making them unreliable indicators of aerodynamic force. We used high-speed three-dimensional kinematics from wind tunnel flights of four lesser dog-faced fruit bats, Cynopterus brachyotis, at speeds ranging from 2.4 to 7.8ms–1 to construct a time-varying model of the mass distribution of the bats and to estimate changes in the position of their COM through time. We compared accelerations calculated by markers on the trunk with accelerations calculated from the estimated COM and we found significant inertial effects on both horizontal and vertical accelerations. We discuss the effect of these inertial accelerations on the long-held idea that, during slow flights, bats accelerate their COM forward during 'tip-reversal upstrokes', whereby the distal portion of the wing moves upward and backward with respect to still air. This idea has been supported by the observation that markers placed on the body accelerate forward during tip-reversal upstrokes. As in previously published studies, we observed that markers on the trunk accelerated forward during the tip-reversal upstrokes. When removing inertial effects, however, we found that the COM accelerated forward primarily during the downstroke. These results highlight the crucial importance of the incorporation of inertial effects of wing motion in the analysis of flapping flight.

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40

Iriarte-Díaz, José, Daniel K. Riskin, David J. Willis, Kenneth S. Breuer, and Sharon M. Swartz. "Whole-body kinematics of a fruit bat reveal the influence of wing inertia on body accelerations." Journal of Experimental Biology 214, no. 9 (2011): 1546–53. https://doi.org/10.5281/zenodo.13450747.

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(Uploaded by Plazi for the Bat Literature Project) The center of mass (COM) of a flying animal accelerates through space because of aerodynamic and gravitational forces. For vertebrates, changes in the position of a landmark on the body have been widely used to estimate net aerodynamic forces. The flapping of relatively massive wings, however, might induce inertial forces that cause markers on the body to move independently of the COM, thus making them unreliable indicators of aerodynamic force. We used high-speed three-dimensional kinematics from wind tunnel flights of four lesser dog-faced fruit bats, Cynopterus brachyotis, at speeds ranging from 2.4 to 7.8ms–1 to construct a time-varying model of the mass distribution of the bats and to estimate changes in the position of their COM through time. We compared accelerations calculated by markers on the trunk with accelerations calculated from the estimated COM and we found significant inertial effects on both horizontal and vertical accelerations. We discuss the effect of these inertial accelerations on the long-held idea that, during slow flights, bats accelerate their COM forward during 'tip-reversal upstrokes', whereby the distal portion of the wing moves upward and backward with respect to still air. This idea has been supported by the observation that markers placed on the body accelerate forward during tip-reversal upstrokes. As in previously published studies, we observed that markers on the trunk accelerated forward during the tip-reversal upstrokes. When removing inertial effects, however, we found that the COM accelerated forward primarily during the downstroke. These results highlight the crucial importance of the incorporation of inertial effects of wing motion in the analysis of flapping flight.

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Kim, Jinwoo, and Seongjin Yim. "Design of a Suspension Controller with Human Body Model for Ride Comfort Improvement and Motion Sickness Mitigation." Actuators 13, no. 12 (2024): 520. https://doi.org/10.3390/act13120520.

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This paper presents a method to design a suspension controller with a human body model for ride comfort improvement and motion sickness mitigation. Generally, it has been known that the vertical acceleration of a sprung mass should be reduced for ride comfort. On the other hand, recent studies have shown that, combined, the vertical acceleration and pitch rate of a sprung mass are key factors that cause motion sickness. However, those variables have been considered with respect to the center of gravity of a sprung mass. For motion sickness mitigation, the vertical acceleration of a human head should be also considered. In this paper, the vertical accelerations and pitch rates of a sprung mass and a human head are controlled by a suspension controller for ride comfort improvement and motion sickness mitigation. For the controller design, a half-car and human body models are adopted. With those models, several types of static output feedback suspension controller are designed with linear quadratic optimal control methodology. To reduce the pitch rate of the sprung mass and the vertical acceleration of the head, a filtered-X LMS algorithm is adopted as an adaptive feedforward algorithm and combined with the static output feedback controllers. A frequency response analysis and simulation are performed with the designed controllers on vehicle simulation software, CarSim®. From the simulation results, it is shown that the proposed controllers can effectively reduce the vertical accelerations and the pitch rate of the sprung mass and the human head.

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Brown, Derrick D., Jurjen Bosga, and Ruud G. J. Meulenbroek. "Effects of Mirror and Metronome Use on Spontaneous Dance Movements." Motor Control 25, no. 1 (2021): 75–88. http://dx.doi.org/10.1123/mc.2020-0012.

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This study investigated effects of mirror and metronome use on spontaneous upper body movements by 10 preprofessional dancers in a motor task in which maximally diverse upper body movement patterns were targeted. Hand and trunk accelerations were digitally recorded utilizing accelerometers and analyzed using polar frequency distributions of the realized acceleration directions and sample entropy of the acceleration time. Acceleration directions were more variably used by the arms than by the torso, particularly so when participants monitored their performance via a mirror. Metronome use hardly affected the predictability of the acceleration time series. The findings underscore the intrinsic limitations that people experience when being asked to move randomly and reveal moderate effects of visual and acoustic constraints on doing so in dance.

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Srivastava, Lalit M., U. E. Edemeka, and Vijai P. Srivastava. "Effects of External Body Accelerations on Blood Flow." Japanese Journal of Applied Physics 33, Part 1, No. 6A (1994): 3648–55. http://dx.doi.org/10.1143/jjap.33.3648.

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Edwards, Emma, Bert Bond, Timothy P. Holsgrove, Jerry Hill, Ryan Baker, and Genevieve K. R. Williams. "Stirred Not Shaken: A Longitudinal Pilot Study of Head Kinematics and Cognitive Changes in Horseracing." Vibration 7, no. 4 (2024): 1171–89. http://dx.doi.org/10.3390/vibration7040060.

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The purpose of this longitudinal pilot study was to add to the body of research relating to head kinematics/vibration in sport and their potential to cause short-term alterations in brain function. In horseracing, due to the horse’s movement, repeated low-level accelerations are transmitted to the jockey’s head. To measure this, professional jockeys (2 male, 2 female) wore an inertial measurement unit (IMU) to record their head kinematics while riding out. In addition, a short battery of tests (Stroop, Trail Making Test B, choice reaction time, manual dexterity, and visual function) was completed immediately before and after riding. Pre- and post-outcome measures from the cognitive test battery were compared using descriptive statistics. The average head kinematics measured across all jockeys and days were at a low level: resultant linear acceleration peak = 5.82 ± 1.08 g, mean = 1.02 ± 0.01 g; resultant rotational velocity peak = 10.37 ± 3.23 rad/s, mean = 0.85 ± 0.15 rad/s; and resultant rotational acceleration peak = 1495 ± 532.75 rad/s2, mean = 86.58 ± 15.54 rad/s2. The duration of an acceleration event was on average 127.04 ± 17.22 ms for linear accelerations and 89.42 ± 19.74 ms for rotational accelerations. This was longer than those noted in many impact and non-impact sports. Jockeys experienced high counts of linear and rotational head accelerations above 3 g and 400 rad/s2, which are considered normal daily living levels (average 300 linear and 445 rotational accelerations per hour of riding). No measurable decline in executive function or dexterity was found after riding; however, a deterioration in visual function (near point convergence and accommodation) was seen. This work lays the foundation for future large-scale research to monitor the head kinematics of riders, measure the effects and understand variables that might influence them.

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Schneider, Klaus, and Ronald F. Zernicke. "Computer Simulation of Head Impact: Estimation of Head-Injury Risk during Soccer Heading." International Journal of Sport Biomechanics 4, no. 4 (1988): 358–71. http://dx.doi.org/10.1123/ijsb.4.4.358.

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With a validated mathematical model of the head-neck consisting of nine rigid bodies (skull, seven cervical vertebrae, and torso), we simulated head impacts to estimate the injury risk associated with soccer heading. Experimental data from head-linear accelerations during soccer heading were used to validate the nine-body head-neck model for short duration impact loading of the head. In the computer simulations, the mass ratios between head mass and impacting body mass, the velocity of the impacting body, and the impact elasticity were varied. Head-linear and angular accelerations were compared to standard head-injury tolerance levels, and the injury risk specifically related to soccer heading was estimated. Based on our choice of tolerance levels in general, our simulations showed that injury risk from angular head accelerations was greater than from linear head accelerations, and compared to frontal impacts, lateral impacts had greater angular and less linear head accelerations. During soccer heading, our simulations indicated an unacceptable injury risk caused by angular head accelerations for frontal and lateral impacts at relatively low impact velocities for children, and at medium range impact velocities for adults. For linear head accelerations, injury risk existed for frontal and lateral impacts at medium range to relatively larger impact velocities for children, while no injury risk was shown for adults throughout the entire velocity range. For injury prevention, we suggest that head-injury risk can be reduced most substantially by increasing the mass ratio between head and impacting body. In soccer with children, the mass of the impacting body has to be adjusted to the reduced head mass of a child, that is, it must be clearly communicated to parents, coaches, and youngsters to only use smaller soccer balls.

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Micó-Amigo, M. Encarna, Idsart Kingma, Erik Ainsworth, et al. "A novel accelerometry-based algorithm for the detection of step durations over short episodes of gait in healthy elderly." Journal of NeuroEngineering and Rehabilitation 13, no. 1 (2016): 38. https://doi.org/10.1186/s12984-016-0145-6.

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Background: The assessment of short episodes of gait is clinically relevant and easily implemented, especially given limited space and time requirements. BFS (body-fixed-sensors) are small, lightweight and easy to wear sensors, which allow the assessment of gait at relative low cost and with low interference. Thus, the assessment with BFS of short episodes of gait, extracted from dailylife physical activity or measured in a standardised and supervised setting, may add value in the study of gait quality of the elderly. The aim of this study was to evaluate the accuracy of a novel algorithm based on acceleration signals recorded at different human locations (lower back and heels) for the detection of step durations over short episodes of gait in healthy elderly subjects.Methods: Twenty healthy elderly subjects (73.7 ± 7.9 years old) walked twice a distance of 5 m, wearing a BFS on the lower back, and on the outside of each heel. Moreover, an optoelectronic three-dimensional (3D) motion tracking system was used to detect step durations. A novel algorithm is presented for the detection of step durations from low-back and heel acceleration signals separately. The accuracy of the algorithm was assessed by comparing absolute differences in step duration between the three methods: step detection from the optoelectronic 3D motion tracking system, step detection from the application of the novel algorithm to low-back accelerations, and step detection from the application of the novel algorithm to heel accelerations.Results: The proposed algorithm successfully detected all the steps, without false positives and without false negatives. Absolute average differences in step duration within trials and across subjects were calculated for each comparison, between low-back accelerations and the optoelectronic system were on average 22.4 ± 7.6 ms (4.0 ± 1.3 % of average step duration), between heel accelerations and the optoelectronic system were on average 20.7 ± 11.8 ms (3.7 ± 1.9 %), and between low-back accelerations and heel accelerations were on average 27.8 ± 15.1 ms (4.9 ± 2.5 % of average step duration).Conclusions: This study showed that the presented novel algorithm detects step durations over short episodes of gait in healthy elderly subjects with acceptable accuracy from low-back and heel accelerations, which provides opportunities to extract a range of gait parameters from short episodes of gait.

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Qiu, Runqi. "Adaptive Control of Vehicle Active Suspension Based on Neural Network Optimization." E3S Web of Conferences 261 (2021): 03046. http://dx.doi.org/10.1051/e3sconf/202126103046.

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An adaptive proportional–integral–derivative (PID) control method based on radial basis function neural network optimization (RBF-PID) is designed for a four-degree-of-freedom active suspension model of a 1/2 vehicle. By building a simulation model of the suspension in MATLAB/Simulink, a C-level road white noise random excitation signal is used as the road input, and the front and rear body vertical accelerations are simulated as the feedback of the control loop, respectively. The simulation results show that the proposed RBF-PID control strategy can effectively suppress the front and rear body acceleration and effectively reduce the centroid vertical acceleration, and improve the performance by about 10.3% compared with the traditional PID control suspension and about 31.2% compared with the passive suspension, but the control effect improvement for the angular acceleration of body pitch angle is not obvious.

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Hennig, Ewald M., Thomas L. Milani, and Mario A. Lafortune. "Use of Ground Reaction Force Parameters in Predicting Peak Tibial Accelerations in Running." Journal of Applied Biomechanics 9, no. 4 (1993): 306–14. http://dx.doi.org/10.1123/jab.9.4.306.

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Ground reaction force data and tibial accelerations from a skin-mounted transducer were collected during rearfoot running at 3.3 m/s across a force platform. Five repetitive trials from 27 subjects in each of 19 different footwear conditions were evaluated. Ground reaction force as well as tibial acceleration parameters were found to be useful for the evaluation of the cushioning properties of different athletic footwear. The good prediction of tibial accelerations by the maximum vertical force rate toward the initial force peak (r2 = .95) suggests that the use of a force platform is sufficient for the estimation of shock-absorbing properties of sport shoes. If an even higher prediction accuracy is required a regression equation with two variables (maximum force rate, median power frequency) may be used (r2 = .97). To evaluate the influence of footwear on the shock traveling through the body, a good prediction of peak tibial accelerations can be achieved from force platform measurements.

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Pramudita, Jonas A., Shunsuke Kikuchi, and Yuji Tanabe. "Numerical Analysis of Vehicle Occupant Responses during Rear Impact Using a Human Body Model." Applied Mechanics and Materials 566 (June 2014): 480–85. http://dx.doi.org/10.4028/www.scientific.net/amm.566.480.

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Understanding vehicle occupant responses during real-world rear collision accidents is very important in the development of appropriate safety technologies for neck injury lessening. In this study, numerical analysis of vehicle occupant responses during rear impact were conducted by using a human multi-body model, a seat finite element model and crash accelerations obtained from real-world accidents. The human multi-body model was developed based on the body characteristics of a typical Japanese male, including the outer body geometry, inertial properties of body segments and passive joint characteristics. The seat finite element model was extracted from a detailed car finite element model. A small modification was done to the seat model to deal with the rear impact simulations. The crash accelerations were obtained from the drive recorder database of rear collision accidents occurred in Japan. Several crash accelerations were selected and used as input conditions during the rear impact simulations. Kinematic responses of the occupants during the accidents can be reasonably predicted by the simulations. Furthermore, different level of accelerations leads to different kinematics responses that may cause variation in injury occurrence and injury severity.

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KIM, JI-WON, YU-RI KWON, JAE-HOON HEO, et al. "ACCELERATION PATTERN OF THE UPPER BODY DURING LEVEL WALKING IN PATIENTS WITH PARKINSON'S DISEASE." Journal of Mechanics in Medicine and Biology 16, no. 08 (2016): 1640025. http://dx.doi.org/10.1142/s021951941640025x.

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The aim of this study was to investigate the effects of Parkinson's disease (PD) on upper body acceleration patterns during level walking. Twenty-three patients with PD and 29 controls of similar age participated in this study. Subjects walked along a 12 m linear walkway at self-selected comfortable speeds. Upper body accelerations were measured using three-axis accelerometers located at the pelvis, shoulder, and head. Acceleration magnitude, stride-to-stride irregularity, and degree of coupling among three body parts were derived from the acceleration signals. In the vertical (supero-inferior) direction, PD patients exhibited a smaller acceleration magnitude, a more irregular pattern, and less coupling of acceleration among body parts compared to the controls ([Formula: see text]). In the anterio-posterior (AP) direction, acceleration magnitude at the pelvis in PD patients was smaller than that in the controls ([Formula: see text]). In addition, the phase lag of AP head acceleration from shoulder and pelvis was smaller in PD patients than in the controls ([Formula: see text]). These results suggest that PD patients walk with reduced ankle power generation and a more rigid upper body in the AP direction and with more irregular muscle force generation in the SI direction.

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Journal articles on the topic 'Body accelerations'

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