| 1. |
- Ghaffari, Ghazaleh, 1985, et al.
(author)
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Female kinematics and muscle responses in lane change and lane change with braking maneuvers
- 2021
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In: Traffic Injury Prevention. - : Informa UK Limited. - 1538-957X .- 1538-9588. ; 22:3, s. 236-241
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Journal article (peer-reviewed)abstract
- Objective: The primary aim of this article is to extensively study female occupant kinematics and muscle activations in vehicle maneuvers potentially occurring in precrash situations and with different seat belt configurations. The secondary aim is to provide validation data for active human body models (AHBMs) of female occupants in representative precrash loading situations. Methods: Front seat female passengers wearing a 3-point seat belt, with either standard or pre-pretensioning functionality, were subjected to multiple autonomously carried-out lane change and lane change with braking maneuvers while traveling at 73 km/h. This article quantifies the head center of gravity and T1 vertebra body (T1) linear and rotational displacements. This article also includes surface electromyography (EMG) data collected from 38 muscles in the neck, torso, and upper and lower extremities, all normalized by maximum voluntary contraction (MVC). The raw EMG data were filtered, rectified, and smoothed. Separate Wilcoxon signed-rank tests were performed on EMG onset and amplitude as well as peak displacements of head and T1 considering 2 paired samples with the belt configuration as an independent variable. Results: Significantly smaller lateral and forward displacements for head and T1 were found with the pre-pretensioner belt versus the standard belt (P <.05). Averaged muscle activity, mainly in the neck, lumbar extensor, and abdominal muscles, increased up to 16% MVC immediately after the vehicle accelerated in the lateral direction. Muscles in the right and left sides of the body displayed differences in activation time and amplitude relative to the vehicle’s lateral motion. For specific muscles, lane changes with the pre-pretensioner belt resulted in earlier muscle activation onsets and significantly smaller activation amplitudes compared to the standard belt (P <.05). Conclusions: The presented results from female passengers complement the previously published results from male passengers subjected to the same loading scenarios. The data provided in this article can be used for validation of AHBMs of female occupants in both sagittal and lateral loading scenarios potentially occurring prior to a crash. Additionally, our results show that a pre-pretensioner belt decreases muscle activation onset and amplitude as well as forward and lateral displacements of head and T1 compared to a standard belt, confirming previously published results.
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| 2. |
- Ghaffari, Ghazaleh, 1985
(author)
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Passenger kinematics in Lane change and Lane change with Braking Manoeuvres using two belt configurations: standard and reversible pre‐pretensioner
- 2018
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In: Conference proceedings International Research Council on the Biomechanics of Injury, IRCOBI. - 2235-3151. ; , s. 493-511
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Conference paper (peer-reviewed)abstract
- The development of integrated safety technologies in modern cars demands comprehensive research to predict human occupant response in pre‐crash and crash situations. The aim of this study is to investigate occupant kinematics and to provide validation data for Human Body Models (HBMs) in simulations of evasive events potentially occurring prior to a crash. Nine front‐seat male passengers, wearing a seat belt in either standard or pre‐tensed configuration prior to the event, were exposed to multiple repeatable lane change and lane change with braking manoeuvres while travelling at 73 km/h. The focus of the study was to analyze the occupant kinematics and belt characteristics. The presented data can be used for validation of HBMs in both sagittal and lateral loading scenarios in simulation of pre‐crash events. Corridors comprising mean ±one standard deviation indicated lower sideways and forward displacements for head centre of gravity and T1, with the prepretensioner belt versus the standard belt. Upper torso and head lateral excursion were similar for lane change and lane change with braking manoeuvres, while the longitudinal excursions were highly influenced.
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| 3. |
- Ghaffari, Ghazaleh, 1985, et al.
(author)
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Passenger muscle responses in lane change and lane change with braking maneuvers using two belt configurations: Standard and reversible pre-pretensioner
- 2019
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In: Traffic Injury Prevention. - : Informa UK Limited. - 1538-957X .- 1538-9588. ; 20:sup1, s. S43-S51
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Journal article (peer-reviewed)abstract
- Objective : The introduction of integrated safety technologies in new car models calls for an improved understanding of the human occupant response in precrash situations. The aim of this article is to extensively study occupant muscle activation in vehicle maneuvers potentially occurring in precrash situations with different seat belt configurations. Methods : Front seat male passengers wearing a 3-point seat belt with either standard or pre-pretensioning functionality were exposed to multiple autonomously carried out lane change and lane change with braking maneuvers while traveling at 73 km/h. This article focuses on muscle activation data (surface electromyography [EMG] normalized using maximum voluntary contraction [MVC] data) obtained from 38 muscles in the neck, upper extremities, the torso, and lower extremities. The raw EMG data were filtered, rectified, and smoothed. All muscle activations were presented in corridors of mean ± one standard deviation. Separate Wilcoxon signed ranks tests were performed on volunteers’ muscle activation onset and amplitude considering 2 paired samples with the belt configuration as an independent factor. Results : In normal driving conditions prior to any of the evasive maneuvers, activity levels were low (<2% MVC) in all muscles except for the lumbar extensors (3–5.5% MVC). During the lane change maneuver, selective muscles were activated and these activations restricted the sideway motions due to inertial loading. Averaged muscle activity, predominantly in the neck, lumbar extensor, and abdominal muscles, increased up to 24% MVC soon after the vehicle accelerated in lateral direction for all volunteers. Differences in activation time and amplitude between muscles in the right and left sides of the body were observed relative to the vehicle’s lateral motion. For specific muscles, lane changes with the pre-pretensioner belt were associated with earlier muscle activation onsets and significantly smaller activation amplitudes than for the standard belt (P <.05). Conclusions : Applying a pre-pretensioner belt affected muscle activations; that is, amplitude and onset time. The present muscle activation data complement the results in a preceding publication, the volunteers’ kinematics and the boundary conditions from the same data set. An effect of belt configuration was also seen on previously published volunteers’ kinematics with lower lateral and forward displacements for head and upper torso using the pre-pretensioner belt versus the standard belt. The data provided in this article can be used for validation and further improvement of active human body models with active musculature in both sagittal and lateral loading scenarios intended for simulation of some evasive maneuvers that potentially occur prior to a crash.
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| 4. |
- Ghaffari, Ghazaleh, 1985
(author)
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Postural and Muscular Responses of Car Occupants under Pre-Crash Conditions
- 2021
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Doctoral thesis (other academic/artistic)abstract
- Advanced integrated safety technologies in modern cars such as collision avoidance intervention and pre-crash activated restraint systems require comprehensive research on how vehicle occupants respond to these systems. The aim of this thesis is to provide insights into car passengers’ body kinematics and muscle activations in representative pre-crash circumstances with respect to two belt configurations (i.e., standard versus pre-pretensioner). Another objective is to explore the influence of occupants’ individual characteristics — namely age, stature, and sex — on their body kinematics. A complementary objective is to provide validation data for human body models (HBMs). A set of in-vehicle experiments was carried out in which front-row passengers were traveling at 73 km/h and subjected to autonomous lane changes and lane changes combined with braking, each with two belt configurations: standard and reversible pre-pretensioner belts. Volunteer muscle activations were measured by the surface electromyography (EMG) technique. Transformation of coordinates corresponding to several film targets attached to the head and upper torso was used to calculate the kinematics in 3-D. The volunteers’ EMG and kinematics were processed, and the quantified kinematics were statistically explored using principal component analysis and linear mixed model. Compared to the standard belt, pre-tensioning the seat belt prior to the maneuvers reduced lateral and forward displacements of the head and upper torso significantly. Seat belt pre-tensioning was also associated with earlier muscle activation onset and significantly lower activation amplitude for specific muscles. The influence of sex, stature, and their interaction on the head and upper torso kinematics were found statistically significant but accounted for a small amount of variance. A statistical model was developed which can predict head and upper torso kinematics of occupants with different stature and sex. The data provided in this thesis can be used for further enhancement and validation of HBMs. Consequently, the design of integrated safety systems in modern cars can benefit from more biofidelic models representing a wide range of population more accurately. Further statistical investigations for other types of omnidirectional loading scenarios and, preferably with a larger and more diverse sample space, are required to establish more accurate statistical models that can be generalized to the whole population.
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| 5. |
- Ghaffari, Ghazaleh, 1985
(author)
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Volunteer Kinematics and Muscle Activity in Dynamic Events Representative of Pre-crash Scenarios, Evaluation Data for Human Body Models
- 2018
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Licentiate thesis (other academic/artistic)abstract
- Advanced integrated safety technologies in modern cars such as collision avoidance intervention and pre-crash activated restraint systems involve comprehensive research on how vehicle occupants respond to these systems in pre-crash situations. Human Body Models (HBMs) are mathematical tools developed to predict human responses and injury outcomes in different pre-crash and in-crash situations. In recent years, introducing muscular activation strategies into the HBMs has enhanced the accuracy of model responses in these situations. The development and validation of biofidelic HBMs intended for studies of pre-crash situations require information on kinematics and muscle activation of vehicle occupants in similar circumstances. This information can be obtained through volunteer experiments representative of pre-crash loading situations. To provide validation data for HBMs, this thesis investigates volunteer responses in evasive manoeuvres potentially occurring prior to a crash. Kinematics and muscle responses of front-seat male passengers travelling at 73 km/h together with vehicle dynamics and boundary conditions were measured in the following scenarios: autonomous lane change and autonomous lane change combined with braking, each with two belt configurations; standard and reversible pre-pretensioner belts. The surface electromyography method was used to measure muscle activity and the data was then normalised using maximum voluntary contraction (MVC) values. Transformation of coordinates corresponding to several film targets attached to the head and torso was used to calculate head centre of gravity (CoG) and upper torso kinematics in 3-D. All data were presented in corridors comprising mean ± one standard deviation. Muscle activity as well as head and torso motion were influenced by type of the manoeuvre and the belt configuration used. In addition to lateral motion observed in lane changes, forward displacement of the head and upper torso were also observed in lane changes with braking. Differences in activation time and amplitude between muscles in the right and left side of the body with respect to the vehicle’s lateral motion were noted. Compared to the standard belt, pre-tensioning the seat belt prior to the manoeuvres reduced lateral and forward displacement of head and upper torso. Seat belt pre-tensioning was also associated with earlier muscle activation onset and significantly lower activation amplitude for specific muscles. The data provided in this thesis can be used for further enhancement and validation of HBMs capable of simulating muscles activity in simulation of pre-crash situations, involving both sagittal and lateral loading. In addition to the volunteer data being suitable for directly assessing the design of integrated safety systems, the HBMs validated against the volunteer data can facilitate the prediction of injury outcomes in crashes that may follow evasive manoeuvres. As such, the HBMs would be applicable in the optimisation of integrated safety technologies targeted at the reduction of injuries of vehicle occupants. Further studies identifying responses of other occupant categories based on seated position, gender, age, stature and BMI are needed for subject-specific optimisation of safety systems in modern cars. Furthermore, studies on volunteer responses in other types of omnidirectional loading scenarios as well as the effect of being unprepared compared to anticipatory or voluntary responses, can help understand human motor control strategies specific to pre-crash situations.
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| 6. |
- Larsson, Emma, 1991, et al.
(author)
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Passenger Kinematics Variance in Different Vehicle Manoeuvres - Biomechanical Response Corridors Based on Principal Component Analysis
- 2022
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In: Conference proceedings International Research Council on the Biomechanics of Injury, IRCOBI. - 2235-3151. ; 2022-September, s. 793-843
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Conference paper (peer-reviewed)abstract
- This study explores the influence of occupant characteristics and belt type on occupant kinematics in evasive manoeuvres and provides models for construction of response corridors. Data originated from evasive manoeuvres with male and female volunteers. Principal component analysis and linear mixed models were used on selected data to create predictive models for kinematics and belt time histories, using belt configuration, sex, age, stature, and BMI as co-variates. Monte Carlo simulations of resulting models were used to generate upper and lower response corridor limits around the predicted responses. For translational and rotational displacements of the head and the torso, the first three principal components together captured 91%-99% of the variance in the responses. Belt configuration, sex, age, stature, BMI, and their interaction effects were found statistically significant (p < 0.05) in the linear mixed model analysis in lane changes, braking and U-turns at 40 km/h but not in U-turns at 30 km/h or when aware of turn. Response corridors for average sex, stature and BMI, were provided. In conclusion, the models and data provided can be used for validation of human body models with a range of anthropometries and in different manoeuvres and belt configurations potentially occurring in pre-crash manoeuvres.
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| 7. |
- Saremi, Amin, et al.
(author)
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An acoustic echo canceller optimized for hands-free speech telecommunication in large vehicle cabins
- 2023
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In: EURASIP Journal on Audio, Speech, and Music Processing. - : Springer. - 1687-4714 .- 1687-4722. ; 2023:1
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Journal article (peer-reviewed)abstract
- Acoustic echo cancelation (AEC) is a system identification problem that has been addressed by various techniques and most commonly by normalized least mean square (NLMS) adaptive algorithms. However, performing a successful AEC in large commercial vehicles has proved complicated due to the size and challenging variations in the acoustic characteristics of their cabins. Here, we present a wideband fully linear time domain NLMS algorithm for AEC that is enhanced by a statistical double-talk detector (DTD) and a voice activity detector (VAD). The proposed solution was tested in four main Volvo truck models, with various cabin geometries, using standard Swedish hearing-in-noise (HINT) sentences in the presence and absence of engine noise. The results show that the proposed solution achieves a high echo return loss enhancement (ERLE) of at least 25 dB with a fast convergence time, fulfilling ITU G.168 requirements. The presented solution was particularly developed to provide a practical compromise between accuracy and computational cost to allow its real-time implementation on commercial digital signal processors (DSPs). A real-time implementation of the solution was coded in C on an ARM Cortex M-7 DSP. The algorithmic latency was measured at less than 26 ms for processing each 50-ms buffer indicating the computational feasibility of the proposed solution for real-time implementation on common DSPs and embedded systems with limited computational and memory resources. MATLAB source codes and related audio files are made available online for reference and further development.
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| 8. |
- Sjödahl, Jenny, et al.
(author)
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Response of the muscles in the pelvic floor and the lower lateral abdominal wall during the Active Straight Leg Raise in women with and without pelvic girdle pain: An experimental study
- 2016
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In: Clinical Biomechanics. - : Elsevier BV. - 0268-0033 .- 1879-1271. ; 35, s. 49-55
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Journal article (peer-reviewed)abstract
- Background The relationship between activation of the stabilizing muscles of the lumbopelvic region during the Active Straight Leg Raise test and pelvic girdle pain remains unknown. Therefore, the aim was to examine automatic contractions in relation to pre-activation in the muscles of the pelvic floor and the lower lateral abdominal wall during leg lifts, performed as the Active Straight Leg Raise test, in women with and without persistent postpartum pelvic girdle pain. Methods Sixteen women with pelvic girdle pain and eleven pain-free women performed contralateral and ipsilateral leg lifts, while surface electromyographic activity was recorded from the pelvic floor and unilaterally from the lower lateral abdominal wall. As participants performed leg lifts onset time was calculated as the time from increased muscle activity to leg lift initiation. Findings No significant differences were observed between the groups during the contralateral leg lift. During the subsequent ipsilateral leg lift, pre-activation in the pelvic floor muscles was observed in 36% of women with pelvic girdle pain and in 91% of pain-free women (P = 0.01). Compared to pain-free women, women with pelvic girdle pain also showed significantly later onset time in both the pelvic floor muscles (P = 0.01) and the muscles of the lower lateral abdominal wall (P < 0.01). Interpretation We suggest that disturbed motor activation patterns influence women's ability to stabilize the pelvis during leg lifts. This could be linked to provocation of pain during repeated movements. © 2016 Elsevier Ltd. All rights reserved.
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