水陆两栖球形机器人辅助鳍的水动力特性

Hydrodynamic performance of assistant fins of an amphibious spherical robot

为将传统球形机器人的应用领域从陆地拓展到水域,通过在球壳上黏附辅助鳍,增大球形机器人水面运动的推进力,设计一种紧凑高效的水陆两栖球形机器人。分析特殊平面形状的单片辅助鳍在运动周期中入水面积和形心的变化规律,基于机翼理论推导液体作用在辅助鳍上的升力和阻力计算公式,给出水平分力和竖直分力表达式。利用傅里叶级数对水平分力和竖直分力进行拟合,针对球壳上不同数量辅助鳍配置方式,给出傅里叶级数表示的水平分力合力和竖直分力合力计算公式。研究结果表明,增大球壳旋转角速度和辅助鳍入水面积可提高水平分力;水平分力合力呈现周期性变化规律;增加配置的辅助鳍数量可增大水平分力合力的平均值,减小合力的波动幅度;辅助鳍结构能够给球形机器人水面运动提供持续稳定的推进力。

To expand the application of a traditional spherical robot from the terrestrial environment to the aquatic environment,a compact and efficacious amphibious spherical robot design was proposed by attaching assistant fins onto the outer spherical shell to increase the robot's propulsion force.The wetted surface area of one assistant fin and its centroid were calculated,then equations of the lift force and the drag force were derived based on the airfoil theory,and afterwards equations of the horizontal force and the vertical force were presented.The horizontal force and the vertical force were fitted separately using Fourier series,and after that,the equations of the resultant force exerted on all those fins submerged into the water were given.The results show that increasing the rotational speed of the spherical shell and the wetted surface area of the fin increase the horizontal force.Attaching more fins onto the spherical shell increases the average of the resultant horizontal force,which changes periodically,and decreases its undulation.The assistant fins provide steady propulsion force for the spherical robot.