A statistical method for predicting automobile driving posture

A new model for predicting automobile driving posture is presented. The model, based on data from a study of 68 men and women in 18 vehicle package and seat conditions, is designed for use in posturing the human figure models that are increasingly used for vehicle interior design. The model uses a series of independent regression models, coupled with data-guided inverse kinematics, to fit a whole-body linkage. An important characteristic of the new model is that it places greatest importance on prediction accuracy for the body locations that are most important for vehicle interior design: eye location and hip location. The model predictions were compared with the driving postures of 120 men and women in five vehicles. Errors in mean eye location predictions in the vehicles were typically less than 10 mm. Prediction errors were largely independent of anthropometric variables and vehicle layout. Although the average posture of a group of people can be predicted accurately, individuals' postures cannot be predicted precisely because of interindividual posture variance that is unrelated to key anthropometric variables. The posture prediction models developed in this research can be applied to posturing computer-rendered human models to improve the accuracy of ergonomic assessments of vehicle interiors.     

Endurance time of grip-force as a function of grip-span, posture and anthropometric variables

The time to volitional exhaustion (endurance time) for sustained contractions is considered as a valid parameter to quantify fatigue and to determine the required rest pauses between two successive contractions. In this study, the effects of grip-span, shoulder posture and anthropometric characteristics on endurance time of grip-force during sustained 30% of maximal voluntary grip-force were investigated. Both subjective and objective measures of fatigue were used in determining the endurance times. Twelve male subjects performed sustained isometric handgrip contractions using a handgrip dynamometer at the combinations of three different grip span settings and two shoulder postures. The investigated three grip spans were the optimal, 2 cm narrower than the optimal, and 2 cm wider than the optimal. The investigated two shoulder postures were neutral and 25° flexion. The outcome measures were: endurance time, surface electromyography of related forearm muscles, heart rate, blood pressure, and ratings of perceived discomfort/pain. The results indicate that the endurance time decreases significantly as the grip span deviates from the optimal in both directions. On the other hand, the considered shoulder postures did not have a significant effect on the endurance time. Further analysis indicated a significant negative correlation between endurance time and rest pause and a marginal positive correlation between maximum voluntary grip-force and rest pause. Body mass index, and volume of forearm and hand had also significant negative correlation with endurance time. The comparisons are made with a number of existing endurance models and the impact of findings are discussed.

Relevance to industry

In accurate establishment of the time standards, muscular fatigue allowances need to be taken into account. The endurance time for sustained isometric contractions is correlated with the required rest allowances (pauses) for intermittent static contractions; and therefore, required muscular fatigue allowances can be estimated from the endurance times.     

Effects of keyboard tray geometry on upper body posture and comfort

The effects of a downward-tilting (DT) keyboard tray on wrist posture, seated posture and self-assessed musculoskeletal discomfort were investigated in a field experiment. Thirty-eight professional office workers were studied. A pretest assessed how they typed using either a conventional keyboard on a desk or on an articulating keyboard tray, and with or without wrist rests. Workers were randomly allocated to a control (n = 15) or test group (n = 23) that used their existing keyboard in a DT system. A post-test was conducted 3 weeks later. Results showed no significant changes in wrist posture, seated posture or reports of musculoskeletal discomfort for the control group, and approximately 50% of typing wrist movements put the hand in a neutral zone. There were significant improvements in wrist posture, seated posture and upper body musculoskeletal discomfort for the test group using the DT system. Over 80% of typing wrist movements put the hand into a neutral zone with the DT arrangement. Reactions to using a conventional keyboard on a DT system were positive.     

Effects of keyboard tray geometry on upper body posture and comfort

The effects of a downward-tilting (DT) keyboard tray on wrist posture, seated posture and self-assessed musculoskeletal discomfort were investigated in a field experiment. Thirty-eight professional office workers were studied. A pretest assessed how they typed using either a conventional keyboard on a desk or on an articulating keyboard tray, and with or without wrist rests. Workers were randomly allocated to a control (n= 15) or test group (n= 23) that used their existing keyboard in a DT system. A post-test was conducted 3 weeks later. Results showed no significant changes in wrist posture, seated posture or reports of musculoskeletal discomfort for the control group, and ? 50% of typing wrist movements put the hand in a neutral zone. There were significant improvements in wrist posture, seated posture and upper body musculoskeletal discomfort for the test group using the DT system. Over 80% of typing wrist movements put the hand into a neutral zone with the DT arrangement. Reactions to using a conventional keyboard on a DT system were positive.     

Effects of using head-up display in automobile context on attention demand and driving performance

This study aimed to investigate the difference in driving performance between drivers’ attention on the head-up display (HUD)/road under low/high road conditions via a driving simulator experiment. Experimental driving included four driving scenarios with attention-on-the-HUD followed by attention-on-the-road or vice versa under high or low driving load conditions. Each scenario took about a 30-min driving consisting of two 15-min sections for each attention location. Forty-eight participants, divided into four groups, drove one of the four scenarios once. Besides driving safely within speed limit, participants were also required to perform detection task and speed limit sign response task. Results revealed that drivers paying attention to the HUD, under both low and high driving load conditions, reacted faster to speed limit sign changes than when paying attention to the road. In addition, attention-to-the-HUD under low driving load condition caused the smallest variation in steering wheel angle and lateral acceleration. These differences can be attributed to the driver's enhanced awareness and the cognitive capture effect, and tended to diminish with increasing driving workload. Finally, attention shift of drivers and the so-called novelty effect for using new technology product were also found.     

The inadequate effect of automobile seating on foot posture and callus development

Driver posture is an important factor to be considered in the ergonomics design process of automobiles. Most decisions during automobile design and manufacture are informed by studying the intricate biomechanical components of human musculoskeletal systems to ensure maximum comfort, safety and well-being during driving. A case study is presented that confirms inappropriate foot position as a causative factor for the development of abnormal lateral/plantar heel callosities when driving a 4 x 4-style vehicle. The driver's foot position was influenced by the seat geometry of the vehicle. Cessation of driving the 4 x 4-style vehicle and driving of an alternative automobile while on holiday for a period of 4 weeks resolved the condition. On return to the 4 x 4-style vehicle, however, the abnormal callus patterns redeveloped while using the same footwear and no change in any other parameters. It is therefore suggested that seat and consequent foot position is an important ergonomic factor that should be addressed in the future design of automobile seating.     

The inadequate effect of automobile seating on foot posture and callus development

Driver posture is an important factor to be considered in the ergonomics design process of automobiles. Most decisions during automobile design and manufacture are informed by studying the intricate biomechanical components of human musculoskeletal systems to ensure maximum comfort, safety and well-being during driving. A case study is presented that confirms inappropriate foot position as a causative factor for the development of abnormal lateral/plantar heel callosities when driving a 4 × 4-style vehicle. The driver's foot position was influenced by the seat geometry of the vehicle. Cessation of driving the 4 × 4-style vehicle and driving of an alternative automobile while on holiday for a period of 4 weeks resolved the condition. On return to the 4 × 4-style vehicle, however, the abnormal callus patterns redeveloped while using the same footwear and no change in any other parameters. It is therefore suggested that seat and consequent foot position is an important ergonomic factor that should be addressed in the future design of automobile seating.     

Joint road geometry estimation and vehicle tracking

Detection and tracking of other vehicles and estimation of lane geometry will be required for many intelligent driver assistance systems in the future. By combining the processing of these two features into a single filter, better utilisation of the available information can be achieved. For instance, it is demonstrated that it is possible to improve the road shape estimate by including information about the lateral movement of leading vehicles.

Statistical evaluation is done by comparing the estimated parameters to true values in varying road and weather conditions. The performance is also related to typical requirements of active safety applications such as adaptive cruise control and a new safety function called emergency lane assist.     

自动驾驶制动控制方案的研究

为了保证车辆在自动驾驶过程中安全、平稳、可靠地实施自动制动控制,应用最优化方法中的非线性规划理论,以控制制动时间最短、保证乘员最舒适为约束条件,对车辆制动控制行为进行了精确的数学建模;并使用MATLAB优化工具箱进行仿真计算,得出了在初速度分别为30 km/h、60 km/h、90 km/h和120 km/h时的车辆在200 m定长距离下以刹车次数、刹车时间、刹车间隔为参数的自动制动控制方案。仿真结果表明,在3090 km/h的低、中速情况下,通过间歇刹车,车辆可以平稳、安全地驻车在200 m处;而对于1     

Ergonomic evaluation of the ambulance interior to reduce paramedic discomfort and posture stress

OBJECTIVE: This study aims to evaluate safety and accessibility of an advanced life support (ALS) ambulance interior. BACKGROUND: The standard ambulance's interior design is unsatisfactory based on perceived discomfort and postures that constrain paramedics and medical staff, resulting in unsafe treatment of patients, mainly when being transported. METHODS: Two procedures were used to evaluate performance during a wide range of rescue tasks: a survey, based on questionnaires, interviews, and observation of paramedics performing routine tasks; and upper body and back posture analysis, based on postural considerations. RESULTS: Findings revealed that 74% of the paramedics stated that the location of the paramedic's seat is inefficient while they perform clinical procedures; 94% found the bench uncomfortable; 77% felt that the vertical distance between the bench and the stretcher is too far; and 86% needed to steady themselves when the vehicle was moving. Posture analysis showed that paramedics undergo several nonneutral back postures, including twisted back (>20 degrees) and sitting with back flexion between 20 degrees and 45 degrees. CONCLUSION: Because the interior of the ALS ambulance was found to be unsatisfactory both to paramedics and patients, alternative design issues are proposed. APPLICATION: The suggested practical layout contains four main modifications: (a) replacing the bench with two adjustable paramedic seats, (b) redesigning the medical cabinet for easy access, (c) adding an adjustable folding seat opposite the two new seats, and (d) adding a swiveling base and lifting apparatus that will accommodate the stretcher and enable better accessibility to patients by the paramedic personnel.     

基于DSP与LabVIEW的汽车行驶姿态参数采集系统设计

设计了一种基于TMS320F2812与LabVIEW的汽车行驶姿态参数采集系统。利用ADIS16355AMLZ三轴陀螺仪灵敏度高、集成度高、测量精度高等特点,系统采用DSP对汽车行驶姿态进行实时数据采集,并通过SPI接口实现两者之间的通信,上位机采用LabVIEW作为开发平台,通过串口实现DSP与上位机的通信。     

Vibration and spinal lengthening in simulated vehicle driving

There is active interest in the relationship between back pain and driving. The availability of a precision stadiometer enabled experiments to be done to explore the effects of simulated driving on the change in spinal length, the hypothesis being that the spinal load would cause a shrinking in the length of the spine. The experiments demonstrated that, when exposed to a combination of vertical and horizontal vibration at 4 Hz the spinal length increased for all eight subjects, whilst under no vibration conditions there was a decrease in the average length. At 6 and 8 Hz there was no statistically significant change in length. The results suggest that there is an unloading of the spine when subjects under simulated driving conditions are exposed to vibrations in two directions at a frequency close to the spine's natural frequency.     

Effects of natural posture imbalance on posture deviation caused by load carriage

PurposeThe purpose of this study was to explore posture deviation variability caused by load carriages depending on natural posture imbalance to provide information about a carrying habit exaggerating an individual's posture imbalance. All people exhibit some imbalance from the standard anatomical pose which assumes alignment with the frontal and median planes. In this study natural posture imbalance is the starting point for determining posture deviation which is posture imbalance resulting from an activity, carrying an item.MethodsSeventeen female participants, 19–37 years old, were recruited from university staff, faculty members, and students. Participants were each scanned wearing their own underwear (bra and panties) in: (a) the anatomical pose (P1) face forward and feet placed at shoulder width without carrying an item, (b) carrying a backpack (P2), (c) carrying a shoulder bag on the right shoulder (P3R) and the left shoulder (P3L), (d) carrying a bag cross-body with a strap placed on the left shoulder to place the weight at the hip level on the right side (P4R) and the strap and handbag placed in the opposite direction (P4L), and (e) carrying a bag with the right hand (P5R) and the left hand (P5L). The bag weight was approximately 10% of a participant's body weight. Five body angles were obtained in each scanning position (eight positions total) for all participants and statistical analyses were conducted for posture assessment. Three statistical test methods were used: (a) Paired t-test to determine posture changes in each loaded position compared to natural posture in P1. (b) Paired t-test to identify differences of the degree of posture changes between right-side load (R) and left-side load (L) positions to determine a posture deviation tendency with asymmetrical load carriages. (c) Bivariate (Pearson) correlation test to examine how natural posture imbalance and posture deviation co-vary.Results(a) Asymmetrical load positions exhibited greater changes on shoulder and spine posture than a symmetrical load position, exhibiting obvious changes in P3 and P4 rather than P5. (b) The degrees and directions of posture deviation resulting from an asymmetrical load carriage varied depending on those of an individual's natural posture imbalance. When a participant exhibited great posture imbalance in P1, significant differences of posture deviation on the shoulder and spine between R and L positions were observed in P3 and P4. (c) Significant correlations between natural posture imbalance and posture deviation resulting from load carriages were found for most body angles.ConclusionsPeople need to be aware of their natural posture imbalance and try to avoid carrying heavy handbags or any type of carriages making their posture imbalance worse to prevent possible further distortion.Relevance to IndustryAlthough this study used handbags and a backpack as the load carrying devices, the way a person carries a load of any type is relevant in many industries and in the military.     

Profiling drivers based on driver dependent vehicle driving features

This work addresses the problem of profiling drivers based on their driving features. A purpose-built hardware integrated with a software tool is used to record data from multiple drivers. The recorded data is then profiled using clustering techniques. k-means has been used for clustering and the results are counterchecked with Fuzzy c-means (FCM) and Model Based Clustering (MBC). Based on the results of clustering, a classifier, i.e., an Artificial Neural Network (ANN) is trained to classify a driver during driving in one of the four discovered clusters (profiles). The performance of ANN is compared with that of a Support Vector Machine (SVM). Comparison of the clustering techniques shows that different subsets of the recorded dataset with a diverse combination of attributes provide approximately the same number of profiles, i.e., four. Analysis of features shows that average speed, maximum speed, number of times brakes were applied, and number of times horn was used provide the information regarding drivers’ driving behavior, which is useful for clustering. Both one versus one (SVM) and one versus rest (SVM) method for classification have been applied. Average accuracy and average mean square error achieved in the case of ANN was 84.2 % and 0.05 respectively. Whereas the average performance for SVM was 47 %, the maximum performance was 86 % using RBF kernel. The proposed system can be used in modern vehicles for early warning system, based on drivers’ driving features, to avoid accidents.     

A new digital human environment and assessment of vehicle interior design

Vehicle interior design directly relates to driver performance measures such as comfort, efficiency, risk of injury, and vehicle safety. A digital human is a convenient tool for satisfying the need to reduce the design cycle in order to save time and money. This paper presents a digital human environment, Santos™, developed at The University of Iowa, and its assessment as applied to the interior design of a Caterpillar vehicle. The digital human environment involves male models and accommodates a large percentage of the operator population (from the 5th percentile to the 95th percentile). It has a user-friendly interface and includes various tools such as posture prediction, reachability check, zone differentiation, and biomechanics assessment for the upper body and hand. The key difference from a traditional digital human environment is that Santos’s environment is optimization-based. This can answer design questions regarding whether the operator can reach relevant controls, what the comfort level is if one can reach the control, and what strength is required of the operator to pull a shift, etc. The illustrative example of a Caterpillar cab is demonstrated using this digital human environment.     

基于车辆行驶数据的驾驶人行为谱分析方法

针对我国驾驶人行为谱的研究尚不完善,专业领域内没有相应的行为谱分析工具的问题,提出了一套针对营运客车的完整的驾驶人驾驶行为谱体系并设计了一套分析工具。首先,设计并定义了驾驶人行为谱的特征指标和评价指标;其次,给出了驾驶人行为谱的特征指标分析、计算方法,采用基于马尔可夫链蒙特卡洛采样和离群点剔除的K-means算法对驾驶人的驾驶风格进行分析,采用回归学习对驾驶人的驾驶技能进行分析;然后,设计了基于车联网、大数据的驾驶人行为谱的基础数据采集和预处理方法;最后,采用Java语言、Spring MVC架构开发出驾驶人行为谱分析工具。将机器学习中的数据挖掘、数据分析算法与交通安全领域相结合,对完善我国驾驶人行为谱框架体系具有理论意义,为我国驾驶人行为谱的研究提供了一个科学、定量化分析的工具,对交管部门规范驾驶人驾驶行为、提高道路安全指数、制定合理的交通安全管理策略具有指导意义。     

Identification of vehicle parameters using stationary driving maneuvers

Using the velocity dependent static gains of the one track model it is shown how special combinations of parameters like cornering stiffness and center of gravity can be estimated. Driving with various speed and a constant cornering radius it is possible to estimate three different gains by measurement of the lateral acceleration, the yaw rate and the vehicle slip angle without knowing the moment of inertia of the vehicle. Results are shown for different measurements of a passenger car.     

越野智能车转向及驱动协调控制

本文以实现智能车在非结构化越野环境中的自主导航为目的,对越野路径识别及轨迹跟踪控制方法开展研究.首先基于视觉传感器和激光传感器实现可行驶路径的分割与提取,并建立了包含车辆转向及驱动的耦合控制系统模型;然后,针对控制系统模型具有非匹配不确定性的特点,采用反演变结构控制算法设计了转向及驱动协调控制器,并引入饱和函数以解决变结构的抖振问题;最后,通过仿真和越野导航试验验证了所提出控制算法的有效性和鲁棒性.     

Role of lateral acceleration in curve driving: driver model and experiments on a real vehicle and a driving simulator

Experimental studies show that automobile drivers adjust their speed in curves so that maximum vehicle lateral accelerations decrease at high speeds. This pattern of lateral accelerations is described by a new driver model, assuming drivers control a variable safety margin of perceived lateral acceleration according to their anticipated steering deviations. Compared with a minimum time-to-lane-crossing (H. Godthelp, 1986) speed modulation strategy, this model, based on nonvisual cues, predicts that extreme values of lateral acceleration in curves decrease quadratically with speed, in accordance with experimental data obtained in a vehicle driven on a test track and in a motion-based driving simulator. Variations of model parameters can characterize "normal" or "fast" driving styles on the test track. On the simulator, it was found that the upper limits of lateral acceleration decreased less steeply when the motion cuing system was deactivated, although drivers maintained a consistent driving style. This is interpreted per the model as an underestimation of curvilinear speed due to the lack of inertial stimuli. Actual or potential applications of this research include a method to assess driving simulators as well as to identify driving styles for on-board driver aid systems.     

The relationship between foot pain, anthropometric variables and footwear among older people

Objective

To verify the prevalence of pain among older people when wearing shoes, and the relationships between foot pain, high-heeled shoes and anthropometric variables.

Method

Both feet of 227 older women and 172 older men were evaluated with respect to anthropometric variables, arch index and foot posture index. The participants were also asked about the presence of foot pain while wearing high-heeled shoes. The data were analyzed using the Chi-square test, Pearson's correlation, MANOVA, multiple regression analysis, t test, and analysis of probability.

Findings

The prevalence of foot pain when wearing shoes was high and was associated with the female gender, however wearing high-heeled shoes was not associated with pain. The women with foot pain presented larger values for the circumferences of the metatarsal heads and the instep (after normalization with the foot length) than those without pain. The men with pain did not present different measurements from those without pain.