切口式单孔腹腔镜连续体手术机器人构型设计和优化

Design and Optimization of Continuum Robot Configuration for Single-port Laparoscopic Surgery

针对现有单孔腹腔镜柔性手术机器人刚度不足,负载能力较差及灵活度低等问题,提出了一种切口式连续体机器人机械臂构型设计方案。考虑柔性机器人工作刚度和灵活性难以同时提高这一瓶颈,结合分层理论(Layerwise theory, LWT)及拉格朗日乘子法对模型构造及尺寸参数进行优化。基于Ⅰ型裂纹模型和应力强度分析,对绳驱机器人的牵引线位限方式进行优化。利用切口式机器人切口间隙和连续体最大可弯曲角度θ的关系图以及有限元分析,提出了切口间距优化策略。通过样机测试验证了各优化方案的可行性和有效性。实验证明,优化后的实验机械臂样机在0.5 N的弯曲反向负载下末端偏移误差在0.5 mm内;在柔性体弯曲角90°的范围内,末端负载0.5 N的偏移量均值为0.27 mm。实验表明提出的优化夹层切口式机器人具有较大的刚度和负载能力,在实际手术场景应用中,柔性体末端受拉或负载器械时仍能够满足所需的姿态要求。

Aiming at the problems of insufficient rigidity,poor load capacity and low flexibility of existing single-port laparoscopic flexible surgical robots,a design scheme of notched continuum robot manipulator is proposed.Considering that the stiffness and flexibility of flexible robots are difficult to improve at the same time,the model structure and size parameters are optimized by layer-Wise theory and Lagrangian multiplier method.Based on the I-type crack model and stress strength analysis,the position restriction form of the traction line of the tendon-drive robot is optimized.Based on the relationship diagram of the notch size and the maximum bendable angle of the continuum as well as the finite element analysis,the optimization method of the notch size is proposed.The feasibility and effectiveness of each optimization scheme are verified by prototype testing.The results of experiments show that the end offset error of the optimized robotic manipulator is within 0.5 mm under the load of 0.5 N,and the average offset error under the end load of 0.5 N is 0.27 mm within the range of 90°bending angle of the flexible body.Experiments show that the proposed optimized sandwiching-notched robot has greater stiffness and load capacity,and still has good control accuracy after loading instruments in actual surgical applications.