Driving Discomfort Evaluation Based On Muscle Force

Along with the progress of science and technology，automobile has become anintegral part of the daily life and the harmful to the health of drivers caused bylong-term driving has become a focus issue. Meanwhile, in order to meet the demandof consumers, the auto manufacturers pay more and more attention to ergonomicsperformance of products, especially driving comfort. However, the previousdiscomfort model based on joint angles could be used to neither reveal the essence offatigue nor optimize the cab package design. In this research, therefore, themusculoskeletal system theory of human biomechanics was applied to automotiveergonomics to study the driving joint moment and muscle force and explain theessential reasons of driving discomfort which offered theoretical foundation tooptimize the cab design.By means of CATIA, the virtual cab was constructed included four mostimportant parameters: H30, L6, H17&PH30.And then, driving posture described bymain joint angles could be attained by RAMSIS, based on the95percentile humanbody model. Additionally, for purpose of quasi-static, the upper limb and lower limbposture was simulating during the course of driving operation.Combined with biomechanics research findings, the chain models of lower limb,upper limb and neck were established. Then, joint moment of lower limb, upper limband neck were calculated and moment curves was drawn by MATLAB.Moment arms of lower limb and upper limb were computed based on theprevious research results after analyzing the joint movement mechanism and thenobjective functions and boundary conditions for calculating muscle force wereformulated via the joint moment. The optimization function Fmincon in MATLABToolbox was used for calculating muscle force and its curve was fitted.Muscle discomfort concept that the muscle load was the evaluation index ofmuscle discomfort was introduced by analyzing the muscle force data. The localjoint discomfort model based on muscles superimposition was defined and used tocalculating the discomfort of ankle joint. Then, the flow graph of solving whole bodydiscomfort model was established and in order to induce the discomfort evaluationmodel weight factor was confirmed when analyzed the correlation coefficients between body discomfort and joint discomfort. Finally, the validity of the researchwas verified via comparing the evaluation model with RAMSIS..