可用于微创手术的毫米级微小并联机器人的设计、制造及实现

Design,Fabrication and Realization of a Parallel Microrobot at the Millimeter Scale for Minimally Invasive Surgery

压电驱动的并联机构具有精度高、刚度大及动态特性好的优点,可实现结构小型化,在微创手术操作领域具有广阔应用前景。提出了一种可用于微创手术的毫米级压电驱动并联机器人。所设计微小机器人由两片压电双晶片驱动,通过设计仿蜻蜓扑翼四杆放大机构将致动器的微小驱动位移转化为末端基臂杆的大范围转动,引入平行四杆机构提高机器人的运动刚度和稳定性。建立了机器人速度雅可比矩阵,通过分析灵巧度和全域性能等运动传递指标对机器人杆件尺寸进行优化。提出基于智能复合微结构的激光微加工和多层复合层压工艺,实现了微小机器人从复杂三维空间多杆件结构到多层材料平面加工、层压、释放及装配的一体化制造。微小机器人整体尺寸为21 mm×26 mm×5.6 mm,质量为3.05 g(包含压电双晶片)。搭建实验平台开环测试了微小机器人在重复跟踪水平直线、竖直直线、圆及正弦轨迹下的运动性能。在55 V电压激励下,实测机器人在开环重复跟踪水平和竖直直线的运动行程、相对误差、准确度均方根误差和重复度均方根误差分别为2.12 mm,0.93%,19.7μm±0.5μm,8.5μm±0.4μm和2.01 mm,0.52%,10.5μm±0.4μm,4.9μm±0.2μm。实验证实了所设计微小并联机器人具有良好的轨迹跟踪精度和重复定位精度。

The parallel mechanism actuatedbypiezoelectricactuators possesses remarkable advantages of high precision,large stiffness,and excellent dynamic characteristics,and can be integrated to miniature size,thus has great potentials in the application of minimally invasive surgery.A piezo-actuated parallel microrobot at the millimeter scale for minimally invasive surgery is developed.The proposed microrobot is driven by two piezoelectric bimorphs independently.Inspired by the flapping wing mechanism of the dragonfly,a bionic four-bar amplification mechanism which converts the micro driving displacement of the piezo actuators into a large rotation of the base link is designed.And a parallelogram linkage mechanism is introduced to enhance the stiffness and stability of the microrobot.The velocity Jacobian matrix of the developed microrobot is established.The optimal dimensions of the robot links are determined by evaluating the dexterity and global conditioning indexes.Then,a laser micromachining and lamination processes based on the smart composite microstructure is proposed for the integrated fabrication of the microrobot prototype.By doing this,the complex three-dimensional structure of the proposed microrobot with multiple links is obtained through a series of fabrication processes including laser cutting,laminating,folding,releasing,and assembling of multiple laminate layers.The fabricated microrobot has dimensions of 21 mmx26 mmx5.6 mm,and a mass of 3.05 g(including actuators).Finally,open-loop experiments are conducted on the tracking performances of the developed microrobot when repeatablely following horizontal line,vertical line,circle,and sinusoidal trajectories.Under an excitation amplitude of 55 V,experimental results show that the motion stroke,relative error,RMSE,and repeatability RMSE of the proposed microrobot are 2.12 mm,0.93%,19.7μm±0.5μm,8.5μm±0.4μm for the horizontal line,and 2.01 mm,0.52%,10.5μm±0.4μm,4.9μm±0.2μm for the vertical line,respectively.Therefore,the developed microrobot demonstrates the high positioning accuracy and effective tracking capabilities.