Currier Todd M, Lheron Samuel, Modarres-Sadeghi Yahya
University of Massachusetts, Amherst, MA 01003, United States of America.
Bioinspir Biomim. 2020 Aug 21;15(5):055006. doi: 10.1088/1748-3190/ab9a14.
Inspired by the fastest observed live fishes, we have designed, built and tested a robotic fish that emulates the fast-start maneuver of these fishes and generates acceleration and velocity magnitudes comparable to those of the live fishes within the same time scale. We have designed the robotic fish such that it uses the snap-through bucking of its spine to generate the fast-start response. We have used a dynamic snap-through buckling model and a series of experiments on a beam under snap-through buckling to describe the robotic fish's motion. Our under-actuated robot relies on passive dynamics of a continuous beam to generate organic waveforms. In its transient fast-start maneuver, our robotic fish produces mode shapes very similar to those observed in live fishes, by going through a snap-through bifurcation. We have also used a nonlinear structural model subjected to a non-conservative eccentric compressive force, which is constrained to act tangential to the structure at all times, coupled with a simple fluid dynamic model to approximate the transient behavior of the robot. We relate the numerical results from our nonlinear model to the dynamics observed in the live system proposing an updated kinematic model to understand the mode shapes observed in the fast-start maneuver of the live fishes. We also report on deploying the robotic fish in a river.
受观察到的游动速度最快的活鱼启发，我们设计、制造并测试了一种机器鱼，它能模拟这些鱼类的快速启动动作，并在相同时间尺度内产生与活鱼相当的加速度和速度大小。我们设计的机器鱼利用其脊柱的快速屈曲来产生快速启动反应。我们使用了动态快速屈曲模型以及在快速屈曲状态下对梁进行的一系列实验来描述机器鱼的运动。我们的欠驱动机器人依靠连续梁的被动动力学来产生有机波形。在其瞬态快速启动动作中，我们的机器鱼通过经历快速屈曲分岔，产生与活鱼中观察到的非常相似的振型。我们还使用了一个受非保守偏心压缩力作用的非线性结构模型，该力始终被约束为与结构相切作用，并结合一个简单的流体动力学模型来近似机器人的瞬态行为。我们将非线性模型的数值结果与在活体系统中观察到的动力学联系起来，提出了一个更新的运动学模型，以理解在活鱼快速启动动作中观察到的振型。我们还报告了在河流中部署机器鱼的情况。
