Key Laboratory of Bionic Engineering (Ministry of Education), Jilin University, Room 218, Bionics Building, 5988# Renmin Street, Changchun, 130025, China.
State Key Laboratory of Automotive Simulation and Control, Jilin University, Room 218, Bionics Building, 5988# Renmin Street, Changchun, 130025, China.
Sci Rep. 2021 Aug 16;11(1):16581. doi: 10.1038/s41598-021-96158-1.
The fast swimming speed, flexible cornering, and high propulsion efficiency of diving beetles are primarily achieved by their two powerful hind legs. Unlike other aquatic organisms, such as turtle, jellyfish, fish and frog et al., the diving beetle could complete retreating motion without turning around, and the turning radius is small for this kind of propulsion mode. However, most bionic vehicles have not contained these advantages, the study about this propulsion method is useful for the design of bionic robots. In this paper, the swimming videos of the diving beetle, including forwarding, turning and retreating, were captured by two synchronized high-speed cameras, and were analyzed via SIMI Motion. The analysis results revealed that the swimming speed initially increased quickly to a maximum at 60% of the power stroke, and then decreased. During the power stroke, the diving beetle stretched its tibias and tarsi, the bristles on both sides of which were shaped like paddles, to maximize the cross-sectional areas against the water to achieve the maximum thrust. During the recovery stroke, the diving beetle rotated its tarsi and folded the bristles to minimize the cross-sectional areas to reduce the drag force. For one turning motion (turn right about 90 degrees), it takes only one motion cycle for the diving beetle to complete it. During the retreating motion, the average acceleration was close to 9.8 m/s in the first 25 ms. Finally, based on the diving beetle's hind-leg movement pattern, a kinematic model was constructed, and according to this model and the motion data of the joint angles, the motion trajectories of the hind legs were obtained by using MATLAB. Since the advantages of this propulsion method, it may become a new bionic propulsion method, and the motion data and kinematic model of the hind legs will be helpful in the design of bionic underwater unmanned vehicles.
潜水甲虫的快速游泳速度、灵活的转弯能力和高效的推进效率主要是通过其两条强大的后腿实现的。与其他水生生物不同，如海龟、水母、鱼类和青蛙等，潜水甲虫可以在不转身的情况下完成后退运动，并且这种推进方式的转弯半径很小。然而，大多数仿生车辆并没有包含这些优势，这种推进方式的研究对于仿生机器人的设计是有用的。在本文中，通过两台同步高速摄像机捕捉到了潜水甲虫的游泳视频，包括前进、转弯和后退，并通过 SIMI Motion 进行了分析。分析结果表明，游泳速度最初迅速增加到动力冲程的 60%时达到最大值，然后减小。在动力冲程中，潜水甲虫伸展其胫节和跗节，两侧的刚毛形状像桨叶，以最大限度地增加横截面积以获得最大推力。在恢复冲程中，潜水甲虫旋转其跗节并折叠刚毛以最小化横截面积以减少阻力。对于一个转弯动作（右转约 90 度），潜水甲虫只需一个运动周期即可完成。在后退运动中，前 25 毫秒内平均加速度接近 9.8 m/s。最后，基于潜水甲虫后腿的运动模式，构建了一个运动学模型，并根据该模型和关节角度的运动数据，使用 MATLAB 获得了后腿的运动轨迹。由于这种推进方式的优势，它可能成为一种新的仿生推进方式，后腿的运动数据和运动学模型将有助于仿生水下无人飞行器的设计。
