Research On Lower Limb Handling Comfort Of Commercial Vehicle Drivers Based On Musculoskeletal Biomechanics

From the design perspective of human-vehicle-environment interaction,the driver’s leg comfort is an important content of the driver’s cockpit design,which directly affects the driver’s handling comfort.Therefore,the use of ergonomics and biomechanics methods to design and evaluate the comfort of commercial vehicle seats and pedals is of great significance for improving the comfort of the driver’s lower limbs and driving safety.In the past,the evaluation of car comfort mainly relied on a large number of subjective evaluation statistics,which lacked corresponding theoretical and data support.With the continuous deepening of ergonomics research,biomechanical analysis has been brought into the evaluation of vehicle handling comfort.Biomechanical analysis can reveal the mechanism of driver fatigue from a more detailed level such as musculoskeletal,and can accurately and systematically establish a drivers’ comfort evaluation system from medical anatomy,sports mechanics and other aspects combined with mathematical models.In this paper,starting from the simulation and experiment,the 95 th percentile driver is selected as the research object and the driver simulation driving platform is built to collect the kinematics(Marker point coordinates),dynamics(ground reaction and pedal resistance)and EMG data of drivers’ lower limbs in different maneuvering states.Based on Opensim software we can reconstruct the driver’s manipulation scene,and then in turn,through the steps of model scaling,inverse kinematics,inverse dynamics,residual reduction and static optimization,the drivers’ changes in the joint angle,joint torque and muscle activation of the lower limbs during the manipulation process can be calculated.Combined with different seat heights,we can analyze the comfort of lower limbs when the drivers are operating the pedals and in different sitting posture under the cruise control of commercial vehicles.Secondly,to analyze the driver’s muscle activation in different maneuvering states,the EMG signal collected in the experiment is processed by band-pass filtering,notching,full-wave rectification,low-pass filtering,etc.Muscle activation is the ratio of the electrical signal generated by the driver’s muscle force in a certain state to the electrical signal generated when the muscle is in the maximum force state.In this paper,the driver’s MVC calibration test is used to obtain the electrical signal under the maximum muscle force state.The results of the pedal manipulation test will be compared with the simulation results to verify the validity of the simulation results.Finally,the discomfort of each muscle is evaluated based on the driver’s muscle activation during manipulation,and a single-factor evaluation set for each muscle is established.Then,the weight coefficients of each muscle to the overall discomfort of lower limbs are given by means of regression analysis and analytic hierarchy process.Based on the discomfort weight coefficients of different muscles we can establish the overall operating discomfort evaluation model of the driver’s lower limbs under different operating conditions.This model can be used to simultaneously evaluate the pedal operating comfort and drivers’ comfort for sitting posture When the vehicls are cruising at a constant speed,which provides a reference for the comfort design of commercial vehicle cabs.