Study On The Influence Of Ergonomic Seat Parameters On The Biomechanical Characteristics Of Human Lower Limbs

In the design of ergonomic seat parameters,most research and evaluation methods are based on static stable posture,while the dynamic process from sitting still to standing is often overlooked.During this brief dynamic process,the force and torque exerted on the joints fluctuate greatly,and joint wear is also more pronounced.Therefore,it is particularly important to study the impact of lower limb biomechanical characteristics during sit to stand exercise.In the seat parameters,seat height and sitting depth have a significant impact on the biomechanics of the lower limbs.In existing research,there are relatively more studies on sitting height,but there is little research on sitting depth,and there is no study combining sitting height and sitting depth.Therefore,this study investigates the impact of sitting and standing movements on the biomechanical properties of the lower limbs from the perspectives of sitting height and sitting depth.This article analyzes the effects of sitting height and sitting depth on the biomechanics of the lower limbs by establishing a mathematical model of the sitting and standing movement process,combined with experimental research.The research content of this article is as follows:(1)Sitting and standing motion process and modeling methods.We have organized the existing research methods for dividing the stages of sitting and standing movements,classifying biomechanical models,and modeling mathematical models.Based on this theoretical foundation,we propose our own modeling methods and research ideas.(2)Kinematics and dynamics modeling of sitting and standing movement process.Simplify the human body as a three link biomechanical rigid body model consisting of the head arm torso,hip joint,thigh,knee joint,calf,ankle joint,and foot,and calculate joint torque from both static and inertial effects.In addition,modeling the connection segments,establishing dynamic force balance equations and torque balance equations on the horizontal and vertical axes for each connection segment of the foot,calf,and thigh,and calculating joint reaction forces and muscle torque.(3)Simulation analysis of sitting and standing motion process.According to the method of dividing human body segments into 15 segments,a 3D rigid body model of the 15 individual segments was established using SolidWorks 3D modeling software,and human motion simulation was performed using ADAMS simulation software.The simulated output torque of the ankle,knee,and hip joints was compared with the torque of each joint calculated by the mathematical model in Chapter 3 to verify the correctness of the mathematical model.(4)Experiment and result analysis.A height adjustable experimental seat,a one-dimensional force platform and a three-dimensional force platform were built,and then a sitting and standing motion experiment was conducted with 22 recruited subjects in cooperation with motion capture.Real time angles of each joint and external force data of the subjects in the process of sitting to the station were obtained through data processing.Finally,the experimental data were brought into the established mathematical model to calculate joint torque,joint reaction force and muscle torque,Analyze the influence of seat parameters on the biomechanical characteristics of the lower limbs during sitting and standing movements based on the calculation results.The research results of the paper indicate that joint torque,joint reaction force,and muscle torque all decrease with the increase of seat height,ankle joint torque decreases with the increase of sitting depth,hip joint torque increases with the increase of sitting depth,and the impact of sitting depth on knee joint torque,joint muscle torque,and joint reaction force shows an opposite trend above and below 100%popliteal height.Overall,When the seat height is 100%popliteal height,the influence of sitting depth on it is relatively small.The research results and mathematical models of the paper can provide reference for seat design,research on lower limb strength and balance in the elderly,lower limb rehabilitation sitting and standing exercise training,and sitting and standing accessory design.