| With a high riding-comfort seat,the car can not only greatly ease the long-distance driving physical and mental fatigue of vehicle occupants to ensure the safer driving,but also potentially improve the psychological acceptance of consumers on car buying.So a high riding-comfort seat is the key technology of vehicle seat and the key to improve the market competitiveness of vehicle product.How to better improve the riding comfort of automobile seats is one of the most important applied research topics.The international mainstream human musculoskeletal mechanics analysis software called Any Body was used to model the size of Chinese adult man and simulate the driver operating posture and occupant natural sitting posture,based on the mechanical characteristics of human skeletal muscle.,The driver's discomfort function was established,based on the changes of the muscle activity of the main working muscle groups and force on bones in different simulation positions.And the advanced clinical medical methods MRI was used to determined the mechanism.The body pressure distribution and subjective evaluation results for automobile seat comfort in test are combined together to provide a quantitative design basis for the comfort design of car seats.The specific contents are as follows:Firstly,a human musculoskeletal model of the car driver on the driving seat in the sitting position was established.The structure and composition of skeletal muscle in human muscle system were introduced.The mechanical model of muscle was eatablished,based on the mechanism of muscle contraction and the principle of muscle strength.Then the driver's model in working position on basis of the basic human musculoskeletal model was established in Any Body software,based on the Hill muscle mechanics model.The key adjustment was to set the human body motion parameters such as the coordinate point,the movement part,the motion mode,the path and the time course,including adding the steering wheel and pedals,establishing a connection between the human body and each human-machine interaction component to carry out the force and solving the problem of constraint.Secondly,in cooperation with China FAW Group Corporation R&D Center project,eight professional commercial vehicle drivers were selected using clinical medical imaging studies to analyze their lumbar MRI images,which could help analyze the mechanism of commercial vehicle drivers prone to occupational disease.The lumbar disc magnetic resonance degeneration grading of MRI images were analyzed in clinical study.By means of digital analysis of spinal sagittal parameters,it was found that the most degenerative areas of the human spinal column in the driver population were the human spinal L4-5 lumbar intervertebral disc and L5-S1 intervertebral lumbar disc,which was consistent with the clinical results.Then,the human musculoskeletal mechanics model was adjusted to be suitable for internal layout of commercial vehicle.The changes of stress between each lumbar intervertebral disc of driver in different angle of the seat-pan and the back-rest were analyzed.The results showed that the L4-5 lumbar disc and the L5-S1 lumbar disc bore the largest force,which was consistent with the MRI and clinical conclusions that the largest forced joint were most likely to get degenerative diseases;What's more,the simulation results showed that the change of steering angle is helpful to reduce the force of the lumbar intervertebral disc.The simulation result showed that the change of back-rest angle is helpful to reduce the force between the lumbar intervertebral discs.Under the condition of satisfying the driving safety,when the back-rest angle was 15°and the seat-pan angle was 3°,the driver's lumbar discs bore the least force,which was much more favorable to their health.Then,the comfort evaluation of car-seats was analyzed using human musculoskeletal model in different sitting positions,based on the analysis of human biomechanics.Through adjusting the angle of the seat-back and seat-pan,waist muscle activity,the stress of thoracic bone and leg muscle activity of different percentiles China adult male passenger car driver and occupant were analyzed.By means of correlation analysis,the main working muscles of the human body were screened and the ride comfort function of drivers was established.A test using real people in the real vehicle was carried out.The EMG changes of the lumbar erector spinae,multifidus muscle,rectus femoris,hamstring,tibialis anterior and gastrocnemius of the real driver in the driving posture were measured and analyzed.The electromyogram signal was denoised by threshold filtering algorithm in wavelet domain.The results were compared with the results of simulation,by which the authenticity and reliability of simulation results were verified.The results showed that the muscle activity of erector spinae was the largest.The lumbar vertebra is the main load-bearing part that supported the sitting driver,and the fourth and fifth joints of the lumbar spine have the largest bearing force.The human thoracic spine mainly bore the support force from the back of the seat,and the main forces focused on the thoracic vertebrae T9,T10 and T12 joints.Actually,the main working muscles and main load-bearing bones of sitting driver and passenger changed almost the same,but there were still some differences between them.Most of the abdominal muscles and the spine internal force were relaxed gradually with the increase of the inclination of the backrest.Most of the leg muscles were also relaxed with the increase of the inclination of the seat-pan.However,when the seat angle was greater than 7.5°,the abdominal muscle activation and spinal internal force suddenly increased,so the seat angle could not be bigger than 7.5°.The results of the test and the simulation analysis were in good agreement.Finally,the static pressure distribution test was performed in the four commercial vehicles which were allocated by China FAW Group Corporation R&D Center,based on the analysis of the characteristics of human biomechanics and the clinical MRI results.Considering material,contour and angle of the seat,five professional commercial vehicle drivers were respectively tested static pressure distribution on the driving seat of four commercial vehicles.Subjective evaluation was also made in the experiment.Through subjective weighting method and objective weighting method,the weights of each evaluation index were calculated and analyzed.The data of subjective evaluation were processed,and the consistency between subjective and objective data was analyzed.The results showed that the degree of hardness,contour and design of Volvo commercial and Mercedes Benz commercial vehicle car seat cushion were more suitable and more securely wrap than the others.The central back ideal support distribution should be consistent with the physiological curve of the human spine.The shape of backrest of the Benz commercial vehicle car seat was more in line with the curve of the human spine and could give better support and better fit to the back of the human body.Comprehensive subjective and objective evaluation results showed that the overall comfort degree of Mercedes Benz commercial driver's seat was higher?... |
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