双半球胶囊内窥镜流体环境姿态稳定性研究

为实现双半球胶囊内窥镜流体环境下精准定位控制,需对双半球胶囊滑滚运动姿态稳定性进行研究。建立了双半球胶囊流体环境滑滚运动动力学模型,对胶囊姿态稳定特性及影响因素进行了数值仿真分析,给出了胶囊姿态稳定控制参数选取方法。仿真和实验结果表明,双半球胶囊内窥镜在流体环境下可实现姿态稳定的滑滚运动,姿态调整时间短,移动速度低,有利于胶囊的精准定位控制。

Precision loss of ball screw mechanism under sliding-rolling mixed motion behavior

The sliding-rolling mixed motion behavior degrades the ball screw’s precision at different levels.Based on the sliding-rolling mixed motion between ball and screw/nut raceway,the ball screw’s precision loss considering different given axial loading and rotational speed working conditions was investigated.Since creep and lubrication relate to sliding and rolling motion wear,the creep and lubrication characteristics are analyzed under different working conditions.Besides,the precision loss was calculated considering the sole influence of sliding behavior between ball and screw and compared with the results from other current models.Finally,research on precision loss owing to the sliding-rolling mixed motion behavior was realized under given working conditions,and suitable wear tests were carried out.The analytical results of precision loss are in good agreement with the experimental test conclusions,which is conducive to better predicting the law of precision loss in stable wear period.

双半球胶囊机器人滑滚驱动机理

为实现双半球胶囊机器人的精准移位,胶囊必须具有慢速移位控制功能。然而,低转速的双半球胶囊慢速运动时,容易受到胃肠凸凹表面的干扰,胶囊姿态稳定性差,精准移位控制困难。为此,提出流体环境内胶囊滑滚驱动控制策略,即通过流体环境内胶囊的高速空转解决姿态稳定控制问题,并利用滑滚运动实现胶囊慢速精确移位。以低雷诺数流体理论和弹流润滑理论为基础,计算双半球胶囊在胃壁表面滑滚运动的流体力和力矩,建立滑滚驱动动力学模型,对胶囊滑滚速度特性进行分析。仿真及实验表明:低雷诺数流体环境下利用滑滚驱动策略实现双半球胶囊慢速稳定移位功能切实可行,滑滚速度可通过改变控制参数实现精确控制,显著提高了胶囊移位精度。研究为借助流体环境改善胶囊的动态性能提供了理论依据。