Design And Performance Analysis Of Redundant Parallel Robot For Fracture Reduction

With the rapid development of social economy and the improvement of urbanization level,fracture caused by accidents caused by vehicles,fracture caused by falling from high altitude caused by infrastructure construction,fracture caused by falls of overweight people and the elderly show an increasing trend year by year.At present,minimally invasive fracture reduction surgery mainly relies on intramedullary nail positioning device.This surgical method has small wound and fast postoperative recovery.However,minimally invasive surgery cannot directly observe the location of fracture.To improve the surgical accuracy,medical staff often need to use X-ray imaging equipment to complete the reduction operation.In the process of multiple fluoroscopy,medical workers will be exposed to radiation for a long time,and with the increase of fracture cases,medical workers will face greater occupational harm.One way to solve this problem is to use robots instead of humans to perform surgery,reducing the radiation exposure of medical workers.According to the above research background,three surgical robot schemes introducing redundancy were proposed based on the Gough-Stewart parallel platform in this paper,and the three schemes were compared and analyzed to find an optimal robot structure suitable for fracture reduction surgery.The main contents of the paper are as follows:Based on the analysis of research progress at home and abroad,considering that the reduction of femoral fracture requires a large driving force,this paper chooses the form of parallel robot as the basic configuration of surgical robot.To make up for the problems of small workspace and complex singularity of the parallel robot,the method of introducing redundancy is selected based on the Gough-Stewart parallel platform,and three schemes of introducing redundancy are proposed.Then the kinematic models of three kinds of redundant parallel mechanisms were established respectively,and the velocity relationship between the driving joint and the executing joint was obtained.A workspace algorithm for analyzing redundant parallel robots is studied.Three kinds of redundant parallel mechanisms are compared and analyzed respectively from two aspects of position workspace and attitude workspace.The position and attitude workspace of the three kinds of redundant parallel mechanisms are shown in the form of images.Then,taking the workspace as the performance index,the utilization ratio of the three redundant parallel mechanisms to the redundant driver was analyzed.In the case of introducing the redundant driver stroke of the same stroke,the change of the workspace of the three redundant drivers with the increase of the redundant driver stroke was compared and analyzed.The analysis results show that the inclined redundant driver has better performance.To analyze the improvement of the singularity avoidance ability of three redundant drive schemes,this paper uses the three-point method to analyze the velocity Jacobian of the mechanism,and uses the dimensionally homogeneous matrix to calculate the condition number distribution and compare.The analysis shows that the inclined redundant driver still has better performance in the expected operating workspace.The dynamic capture equipment was used to verify the analysis of three kinds of redundant parallel mechanisms.The limit cases of position workspace and attitude workspace were extracted to record the experimental data.The experimental results verified the correctness of the workspace analysis method in this paper.Taking the sensitivity as the indirect index,the correctness of the singularity analysis method is verified by measuring and calculating three kinds of sensitivity.Multi-objective and multi-parameter genetic algorithm was used to optimize the parameters of a parallel mechanism with inclined redundant actuators,and the optimal structural parameters suitable for fracture reduction surgery were obtained.