三指灵巧手内力汇交多边形存在性判别算法

抓取内力对三指灵巧手实现稳定抓取具有重要的作用。当手指指端与物体构成有摩擦的固定点接触模型时,三指内力必须位于相应接触点摩擦扇内并交于内力汇交多边形内的一点。因此,内力优化算法的研究必须建立在内力汇交多边形存在的基础之上。基于对物体表面接触位置的几何特性分析,建立摩擦扇存在条件,每个指端接触点的内法矢与接触平面所成夹角小于接触点摩擦圆锥角。通过研究接触点摩擦扇边界线及其交点的相互位置关系,推导内力汇交多边形的存在条件,任意两个摩擦扇的边界线交点中,至少有一个位于第三个摩擦扇的严格内部,或者至少有3个边界线交点位于第三个摩擦扇边界线上。最后构建判别三指内力汇交多边形存在性的通用算法,由此可确定能实现对指端操作力起调整作用的自平衡内力。结合抓取实例说明了判别算法的有效性。

Study on Friction Factor of Developing and Developed Laminnr Flow in Annular－Sector Ducts

The pressure drops of laminar developing and developed flow in Hnnular-sector ducts with small round corner have been investigated experimentally. Numerical simulation has been performed to study the effect of the small round corner on the friction factor in the developed region. It has been found that with the increase in corner radius, the value of fRe decreases. In the range of rc/ro from 0.031 to 0.12,the decrease in fRe varies from 0.048% to 0.1% for the five apex angle computed.