Design And Analysis Of A Fully Gaited Lumbar Dynamic Loading Robot

With the rapid growth of the number of sedentary and low-headed people,lumbar degenerative diseases are gradually showing a trend of youth and high incidence.Lumbar fusion is the gold standard for the treatment of lumbar degenerative diseases,but it can have an impact on the movement of the lower limb joints and the transmission and distribution of loads from the sacroiliac joints,accelerating the degeneration of adjacent segments of the lumbar spine.In order to study the impact of fusion surgery on adjacent segment degenerative diseases,this topic focuses on the key technical issues of the lumbar spine in vitro loading system.The main research contents are as follows:Firstly,based on the characteristics of lumbar spine motion during the full gait cycle and the experimental requirements for in vitro lumbar spine loading operations,the functional requirements of the lumbar spine loading robot are determined.Using a modular design method,a human body mechanism of the lumbar spine dynamic loading machine composed of a gait simulation mechanism and a six dimensional force loading mechanism is proposed,in which the gait simulation mechanism can achieve pelvic posture adjustment,and the six dimensional force loading mechanism can achieve load control.Secondly,the kinematics analysis of the gait simulation mechanism was performed using the standard D-H parameter method,and the forward kinematics solution of the upper lumbar spine fixation point was solved,and the simulation verification of the theoretical results was completed;The Monte Carlo method was used to calculate the space required for lumbar spine fixation points.Solve the inverse position solution and the motion space of the loading point of the six dimensional force loading mechanism,compare the working space of the loading point and the fixed point,and verify the rationality of the mechanism design;The velocity Jacobian matrix and force Jacobian matrix of the loading point to the center point of the lower lumbar spine fixation platform are solved by differential transformation method.Then,a finite element model of the human lumbar spine was established.Starting from the CT image,several modeling software processes(Mimics,Geomagic,Solid Works,and ANSYS)were conducted in turn to finally establish and complete the validation of the lumbar finite element model.The motion data of the lumbar vertebral body measured by this model is within the error range of previous in vitro lumbar spine loading experiments,and is similar to the experimental data of previous lumbar finite element loading experiments.Finally,the dynamic and static characteristics of the lumbar dynamic loading robot were analyzed to verify the rationality of the robot design.Conduct lumbar spine curvature adjustment experiment and full gait dynamic loading experiment simulation to verify the theoretical loading of the lumbar spine dynamic loading robot,and analyze the biomechanical differences between the lumbar spine model during the curvature adjustment process and the full gait motion cycle.The work done in this article provides a reference for the development of a fully gait lumbar dynamic loading robot system for clinical applications and for the analysis of in vitro lumbar loading in full gait.