基于复位路径包络误差和改进人工势力场法的复位机器人安全策略

Safety Strategy of Fracture Reduction Robot Based on the Envelope Error of Reduction Path and Improved Artificial Force Field Method

针对机器人辅助骨折复位操作中的人机协同手术安全问题,提出一种基于复位路径包络误差和改进人工势力场的复位安全策略。根据CT扫描数据,采用逆向建模构建骨折的3D数字化模型,采用A*搜索算法规划避障复位路径。基于临床手术精度要求和术前规划的复位路径,在所规划的复位路径周围构建包络误差面,提出改进的人工势力场法,以无数个包络圆形成的包络误差面建立斥力场,在骨折近端断面处建立引力场,引导复位机器人进行骨折复位,保证机器人辅助骨折复位手术操作被限定于复位路径的包络误差范围内。对基于复位路径包络误差的机器人复位安全策略进行仿真验证,针对骨折复位路径无障碍、有障碍两种情况,分别进行复位操作安全策略的仿真分析。仿真结果表明采用包络误差和改进人工势力场的安全策略时,复位路径完全落在包络误差所限定的范围内,能较好地避开障碍物,且仿真路径与规划路径非常接近,能有效提高机器人复位操作的安全性和精准性。

Aiming at the safety of human-computer cooperative surgery in the robot-assisted long bone fracture reduction operation,a safety strategy of fracture reduction robot is proposed and is based on the envelope error of reduction path and improved artificial field method.According to the patient’s CT scan data,the 3 D digital model of the fracture is constructed by reverse modeling,and the A*search algorithm is used to plan the obstacle avoidance reduction path.Based on the clinical surgical accuracy requirements and planned reduction path,an envelope error surface is constructed around the planned reduction path,and an improved artificial force field is proposed.A repulsive field is established on the envelope error surface formed by the countless enveloping circle,and a gravitational field is established at the end of the long bone.Then,the reduction robot is guided to perform a fracture reduction,and the operation of the robot-assisted fracture reduction operation is limited to the envelope error range of the planned path.The safety strategy of reduction robot based on the envelope error of reduction path is simulated for verification.For two situations of the fracture reduction path no obstacles and the obstacles situation,the simulation of the safety strategy of the reduction operation is carried out,respectively.Simulation results show that adopting the safety strategy based on the envelope error and the improved artificial force field method can ensure the reduction path completely fall within the range defined by the envelope error,which can completely avoid the obstacle,and the simulation path is very close to the planned path,which can effectively improve the safety and precision of the reduction robot operation.