Bioinspiration & Biomimetics最新文献

Traditional locomotion strategies fail in low-Reynolds-number fluid environments, where viscous forces dominate over inertial forces. Microorganisms have developed specialized structures such as cilia and flagella to overcome this challenge, enabling efficient movement through highly resistive environments. Among these organisms,Phytophthorazoospores demonstrate unique locomotion mechanisms that allow them to rapidly spread and attack new hosts while expending minimal energy. In this study, we present the design, fabrication, and testing of a zoospore-inspired robot, which leverages dual flexible planar flagella and oscillatory propulsion mechanisms to emulate the natural swimming behavior of zoospores. Our experiments and theoretical model reveal that both flagellar shape and oscillation frequency strongly influence the robot's propulsion speed, with longer flagella and higher frequencies yielding enhanced performance. Additionally, the anterior flagellum, which generates a pulling force on the body, is dominant in enhancing propulsion efficiency compared to the posterior flagellum's pushing force. This is a significant experimental finding, as it would be challenging to observe directly in biological zoospores, which spontaneously release the posterior flagellum when the anterior flagellum detaches. This work contributes to the development of advanced microscale robotic systems with potential applications in medical, environmental, and industrial fields. It also provides a valuable platform for studying biological zoospores and their unique locomotion strategies.

Harbour seal whiskers, characterised by their wavy morphology and elliptical cross-section, are capable of perceiving minute flow velocities as low as 10^-4m s^-1. This study investigates the hydrodynamics and flow perception mechanisms of three elastically mounted whiskers arranged side-by-side in the wake of a caudal fin, using direct numerical simulations. The whiskers are spaced at centre-to-centre distances ofS/D= 2-4, whereSis the inter-whisker spacing andDis the equivalent narrow-face diameter of whisker model. The vibration responses, hydrodynamic forces, wake patterns, energy transfer mechanisms, and flow-sensing performance of the whiskers were analysed. Two distinct wake-whisker interaction patterns are identified, governed by the side-by-side spacing: (Ⅰ) partially-interacted pattern (S/D⩽ 2), in which the upstream caudal fin vortexes bypass the side whiskers, leading to a direct impact on the side whiskers only; (Ⅱ) fully-interacted pattern (S/D> 2), in which the vortexes are able to pass through the gap between the whiskers, allowing all three whiskers to interact with the wake. The energy transfer analysis reveals that the spanwise and chordwise vortexes of caudal fin selectively enhance or suppress whisker vibrations depending on their relative rotation directions, leading to distinct excitation patterns across different spacing configurations. An optimal wake flow perception is achieved atS/D= 3 through lift-vorticity correlation and mutual information analyses under the studied conditions.

The multi-scale hierarchical structure of the conch shell exhibits exceptional mechanical properties, earning it the reputation as nature's natural armor. Based on structural bionics, this study investigates the self-similar three-dimensional structure of conch shells and analyzes their effects on energy absorption (EA). The universal testing machine results demonstrate that the shell specimens exhibit distinct mechanical properties under different loading conditions. Under transverse compression testing, the gastropod shells showed an average peak load of 442.55 N, compressive strength of 110.62 MPa, and Young's modulus of 13.36 GPa. In axial compression tests, the shells displayed an average peak load of 412.16 N with a mean crushing force of 219.79 N. A mathematical 3D model of the conch was developed based on geometric formulas, complemented by scanner-based sample digitization and reverse reconstruction. Multiphysics simulation tools enabled optimization of key conch topology parameters (α,β,r₀,a,b), while response surface modeling quantified parameter-EA correlations. The optimized structural parameters were determined asα= 86.6,β= 12.2,r₀= 92.5,a= 27.5,b= 37.5.The performance metrics of this structure are as follows: SEA_optim= 13.38 J g^-1, MCF_optim= 13.08 kN, CFE_optim= 0.45, and ULC_optim= 0.33.Our findings establish that energy dissipation performance in conch shells is fundamentally linked to their fractal-like self-similar organization. These findings provide crucial theoretical foundations and experimental references for the optimized design of bio-inspired energy-absorbing structures.

Bio-robots, a novel type of robot based on a brain-machine interface, have shown great potential in search and rescue tasks. Current research is focused on the bio-robot itself, such as locomotion, localization and navigation, but lacks interactions with the external environment. In this paper we propose a new system that allows a rat robot to autonomously explore the border of an unknown field out of sight and then obtain the boundary map. We invented a wearable backpack, which is an embedded system with laser-ranging sensors, inertial measurement units and an ultra-wide band (UWB) module, for the rat robot. Based on the wearable system, a classification method for motion states based on the random forest algorithm and a navigation algorithm based on a finite state machine were developed for the autonomous exploration of the border and tested in a locomotion experiment. With the localization and distance data from the UWB module and laser-ranging sensors, we mapped the distribution of the border using the Ramber-Douglas-Peucker algorithm. The results show that this system could effectively navigate the rat robot to explore the field and accurately detect the border. The accuracy of classification reaches 97.86% and the error rate of border detection is 5.90%. This work provides a novel technology that has potential for practical applications such as prospecting for minerals and search tasks.

Latch-mediated spring actuation systems leverage the interplay of springs and latches to rapidly accelerate a load. In biological systems, elastic energy is often distributed across multiple structures, resulting in forces applied from multiple springs. Here, we specifically examine dual-spring force couples in torque reversal systems. A dual-spring force couple applies forces from recoiling springs at two locations to generate torque. Torque reversal systems transition from spring loading to spring actuation through a change in torque direction. We develop a mathematical model of a dual-spring force couple in a torque reversal system, where one spring is attached to the pivot point of a rigid body. During spring loading, this spring compresses to store elastic energy; during spring actuation, it recoils, driving pivot translation and contributing to rotation. We experimentally validate the model using a physical model. We then vary geometric parameters and the energy partition between the two springs to examine how these factors shape system dynamics. We show how variations in geometry and energy partition influence the rotational, translational and coupling terms in the mathematical model. Finally, we demonstrate that the energetics of these systems must be carefully accounted for to accurately capture how potential energy is transformed into kinetic energy. We hypothesize that dual-spring force couples in torque reversal systems may be prevalent in biological organisms, and that insights from this work can guide the design of spring-actuated mechanisms in robotics.

Biologically-inspired jumping robots have demonstrated remarkable adaptability in complex environments, making them increasingly valuable across various fields. However, effective path planning in obstacle-dense environments for large-scale jumping robots remains a significant challenge. Inspired by independent decision-making in the efficient collaborative behavior of locust swarms, we propose a two-stage curriculum reinforcement learning (TS-CRL) framework for locust-inspired jumping robots. This framework enables individual robots to autonomously determine actions based on local environmental observations during group crossing tasks. TS-CRL incorporates a population-invariant encoder with an attention mechanism, allowing it to efficiently handle an increased number of training robots. Moreover, it employs an actor-critic network architecture based on Kolmogorov-Arnold networks to enhance training performance. To further improve the training efficiency, we divided the policy training process into two stages with gradually increasing environmental complexity. The effectiveness and scalability of TS-CRL were validated through a locust-inspired jumping robot platform in challenging simulation scenarios. Notably, TS-CRL can generate efficient, collision-free paths to guide multiple jumping robots. Compared with typical reinforcement learning algorithms, TS-CRL reduced the average path cost by 13.7% and markedly improved the success rate of robots in reaching the target areas. Finally, we constructed a multi-robot system consisting of locust-inspired jumping robots for experiments in the real world.

The Ocean Sunfish (Mola mola) has one of the most unusual body geometries and swimming strategies of all fish species. Effectively lacking a caudal fin, these fish propel themselves by synchronized flapping of their extremely long dorsal and anal fins-a form of locomotion known as median/paired fin (MPF). Long misunderstood to be poor swimmers,Mola molaare increasingly being recognized for their surprising swimming efficiency and agility. MPF propulsion can be modeled as a combination of pitching and heaving in a hydrofoil, a well-studied phenomenon, and the mechanical simplicity of these motions lend themselves well to the creation of compact and robust propulsion systems. Here, we present a novel bio-inspired marine robotic test platform based on the body geometry and swimming strategy of theMola mola. We analyze the forces generated by various flapping frequencies and patterns (synchronous and asynchronous), and the flow behavior for both single flap events and continuous flapping. We observe that there is a linear trend between flapping frequency and thrust force for both synchronous and asynchronous flapping up to the maximum frequencies obtainable with the current design. We then test the flapping parameters resulting in the highest thrust forces for both flapping patterns in a free-swimming arrangement and show that the synchronous flapping results in larger steady-state swimming speed.

With the emergence of new flapping-wing micro aerial vehicle (FWMAV) designs, a need for extensive and advanced mission capabilities arises. FWMAVs try to adapt and emulate the flight features of birds and flying insects. While current designs already achieve high manoeuvrability, they still almost entirely lack perching and take-off capabilities. These capabilities would enable long-term monitoring and surveillance operations, and more complex and multifaceted missions in cluttered environments. We present the development and testing of a framework that enables repeatable perching and take-off for small- to medium-sized FWMAVs, utilising soft, non-damaging grippers. Thanks to its novel active-passive actuation system, an energy-conserving state can be achieved and indefinitely maintained while the vehicle is perched. This actuation system is inspired by the digital tendon locking mechanism observed in perching birds and allows for high gripping power and minimal energy usage with a low weight penalty. A prototype of the proposed system weighing under 39 g was manufactured and extensively tested on a 110 g flapping-wing robot. Successful free-flight tests demonstrated the full mission cycle of landing, perching and subsequent take-off. The telemetry data recorded during the flights yields extensive insight into the system's behaviour and is a valuable step towards full automation and optimisation of the entire take-off and landing cycle.

Prior spring-mass locomotion models achieve stable gaits by prescribing a constant touchdown angle (TD angle) during the flight phase; however, they either exclude torso modeling or depend on online state feedback to stabilize the pitch angle of the torso. In contrast, evidence from biology and robotics suggests that coordinating monoarticular and biarticular hip-knee muscles supports whole-body stability with the simplified controller without online state feedback. However, this has only been verified through empirical and constructive approaches, rather than through dynamical modeling. To verify this hypothesis, we propose a new mathematical dynamical model, torso-hip-knee three pairs of six springs, a planar locomotion model that consists of a torso and coordinated springs imitating a three-pair six-muscle structure in the upper leg. The proposed dynamical model achieves stable running solely by giving a constant TD angle and a constant kicking angle relative to the torso, which control the dynamics during the flight and stance phases respectively. Numerical analysis utilizing Floquet multipliers demonstrates that self-stability emerges across stiffness parameters of coordinated springs. These results constitute the first mathematical evidence that muscle coordination, including biarticular muscles, can stabilize torso pitch during locomotion and provide guidelines for legged-robot design and rehabilitation assessment.

Environmental stressors such as hypoxia challenge the balance between individual physiological performance and the coordination required for collective behaviors like schooling. Here, we investigate how glass catfish (Kryptopterus vitreolus) modulate locomotor and group-level behavior across a gradient of oxygen saturation (95%-20%) while swimming steadily at a constant cruising speed. We found that tailbeat frequency decreased significantly with declining oxygen (p < 0.0001), alongside reductions in wave speed (p = 0.007). Tailbeat amplitude, by contrast, increased significantly under hypoxia (p < 0.0001), and posterior segment angles showed a slight, non-significant increase, consistent with modestly greater tail bending. Despite these changes, the Strouhal number remained fairly constant, and waveform topology was conserved. School structure, including nearest-neighbor distance and distance to the center of the school, remained stable across oxygen treatments, but with significant variation across individual schools. A clear behavioral threshold was observed below 25% oxygen saturation, beyond which coordinated schooling deteriorated. These findings demonstrate that glass catfish employ internally coordinated, energetically economical kinematic adjustments to preserve group cohesion under metabolic constraint. This strategy highlights a decentralized mechanism for sustaining collective behavior near physiological limits and offers biologically-grounded insights relevant to energy-aware coordination in bioinspired swarms.