To study the ostrich (Struthio camelus) foot sole with an irregular surface and papillae, we designed a multi-angle device to measure its friction properties on sand. The observed macro- and micro-structures of the ostrich foot sole intensified friction by tightly gripping sand particles. The sliding friction of the ostrich foot on a single-layer sand board increased with the enlarging particle size. A loose sand all-direction test showed that the coefficient of friction (COF) of the ostrich foot sole was higher than that of the nonpapillary foot. The COF of the ostrich foot sole minimized to 0.30 at 0° and maximized to 0.61 at 180°, and that of the nonpapillary foot minimized to 0.23 at 300° and maximized to 0.54 at 180°, suggesting the ostrich papillae exerted a friction effect. Significant differences in COF were observed among the ranges 10°–40°, 90° and 120°–350°, indicating the papillae can steadily enhance the frictional performance. This study provides an important theoretical basis for the design of frictional robots for deep space exploration and other soft media.

研究鸵鸟（Struthio camelus) 具有不规则表面和乳突的足底，我们设计了一个多角度装置来测量其在沙子上的摩擦性能。鸵鸟足底观察到的宏观和微观结构通过紧紧抓住沙粒而加剧了摩擦。鸵鸟足在单层砂板上的滑动摩擦力随着粒径的增大而增大。松沙全方位测试表明，鸵鸟足底的摩擦系数（COF）高于非乳头足。鸵鸟足底的COF在0°时最小为0.30，在180°时最大为0.61，非乳头足在300°时最小为0.23，在180°时最大为0.54，表明鸵鸟乳头产生了摩擦作用。在 10°–40°、90° 和 120°–350° 范围内观察到 COF 的显着差异，表明乳头可以稳定地提高摩擦性能。该研究为深空探测等软介质摩擦机器人的设计提供了重要的理论依据。