In this paper, a symmetrical, totally 3D printed, Petal-shaped capsule robot (PCR), with fluid resistance torsion moment-weaken effect, is presented. The distribution of fluid dynamic pressure and torsion moment models on the outer surface of the PCR is established, while a constant swimming velocity mathematical model is derived, to describe the relationship between the pressure gradient and the swimming velocity. The higher the fluid dynamic pressure of the PCR is, the smaller the pressure gradient is. The fluid pressure gradient in the liquid-filled environment is the main reason for the full suspension of the PCR. In order to verify the relationship between the pressure gradient, fluid dynamic pressure and the PCR stable swimming velocity, a hand-held magnetic generator, and four novel capsule robot prototypes are developed. The experiments are performed in transparent acrylic pipes of different diameters. The results show that the torsion moment of the four capsule robots, each designed with different eccentricities, gradually decreases as the pipe diameter and eccentricity values increase. Under the same conditions, the rotating speed and constant swimming velocity of capsule robots A, B, C, and D increased successively, obeying the same law as the pressure gradient, which verified the important role of the fluid pressure gradient. The results fully describe the non-contact swimming motion of PCR, under the sole action of fluid dynamic pressure. The research on the characteristics of the pressure gradient poses a certain reference value for further improving the driving performance of capsule robots, specifically laying a foundation regarding their use for examination and medical operation in the non-structural environment of the GI (gastrointestinal) tract.

在本文中，提出了一种对称的、完全 3D 打印的花瓣形胶囊机器人 (PCR)，具有流体阻力扭转力矩减弱效应。建立了PCR外表面的流体动压分布和扭矩模型，并推导出了恒游速数学模型，描述了压力梯度与游动速度之间的关系。PCR的流体动压越高，压力梯度越小。充满液体的环境中的流体压力梯度是 PCR 完全悬浮的主要原因。为了验证压力梯度、流体动压和 PCR 稳定游泳速度之间的关系，开发了手持式磁力发生器和四个新型胶囊机器人原型。实验在不同直径的透明亚克力管中进行。结果表明，四个设计有不同偏心距的胶囊机器人的扭矩随着管径和偏心距值的增加而逐渐减小。在相同条件下，胶囊机器人A、B、C、D的转速和恒游速度依次增大，与压力梯度遵循相同的规律，验证了流体压力梯度的重要作用。结果充分描述了 PCR 在流体动压的唯一作用下的非接触式游泳运动。压力梯度特性的研究对进一步提高胶囊机器人的驱动性能具有一定的参考价值，