Gliding animals traverse cluttered aerial environments when performing ecologically relevant behaviours. However, it is unknown how gliders execute collision-free flight over varying distances to reach their intended target. We quantified complete glide trajectories amid obstacles in a naturally behaving population of gliding lizards inhabiting a rainforest reserve. In this cluttered habitat, the lizards used glide paths with fewer obstacles than alternatives of similar distance. Their takeoff direction oriented them away from obstacles in their path and they subsequently made mid-air turns with accelerations of up to 0.5 g to reorient towards the target tree. These manoeuvres agreed well with a vision-based steering model which maximized their bearing angle with the obstacle while minimizing it with the target tree. Nonetheless, negotiating obstacles reduced mid-glide shallowing rates, implying greater loss of altitude. Finally, the lizards initiated a pitch-up landing manoeuvre consistent with a visual trigger model, suggesting that the landing decision was based on the optical size and speed of the target. They subsequently followed a controlled-collision approach towards the target, ending with variable impact speeds. Overall, the visually guided path planning strategy that enabled collision-free gliding required continuous changes in the gliding kinematics such that the lizards never attained theoretically ideal steady-state glide dynamics.

Gliding animals change their body shape and posture while producing and modulating aerodynamic forces during flight. However, the combined effect of these different factors on aerodynamic force production, and ultimately the animal’s gliding ability, remains uncertain. Here, we quantified the time-varying morphology and aerodynamics of complete, voluntary glides performed by a population of wild gliding lizards (Draco dussumieri) in a seven-camera motion capture arena constructed in their natural environment. Our findings, in conjunction with previous airfoil models, highlight how three-dimensional (3D) wing shape including camber, planform, and aspect ratio enables gliding flight and effective aerodynamic performance by the lizard up to and over an angle of attack (AoA) of 55° without catastrophic loss of lift. Furthermore, the lizards maintained a near maximal lift-to-drag ratio throughout their mid-glide by changing body pitch to control AoA, while simultaneously modulating airfoil camber to alter the magnitude of aerodynamic forces. This strategy allows an optimal aerodynamic configuration for horizontal transport while ensuring adaptability to real-world flight conditions and behavioral requirements. Overall, we empirically show that the aerodynamics of biological airfoils coupled with the animal’s ability to control posture and their 3D wing shape enable efficient gliding and adaptive flight control in the natural habitat.

5Conducting polymers combine the advantages of metal conductivity with ease in processing and biocompatibility; making them extremely versatile for biosensor and tissue engineering applications. However, the inherent brittle property of conducting polymers limits their direct use in such applications which generally warrant soft and flexible material responses. Addition of fillers increases the material compliance, but is achieved at the cost of reduced electrical conductivity. To retain suitable conductivity 10 without compromising the mechanical properties, we fabricate an electroactive blend (dPEDOT) using low grade PEDOT:PSS as the base conducting polymer with polyvinyl alcohol and glycerol as dopants. Bulk dPEDOT films show a thermally stable response till 110 ºC with over seven fold increase in room temperature conductivity as compared to 0.002 Scm -1 for pristine PEDOT:PSS. We characterized the nonlinear stress-strain response of dPEDOT, well described using a Mooney-Rivlin hyperelastic model, 15 with ductility of ~five times its original length and report elastomer-like moduli. Dynamic mechanical analysis shows constant storage moduli over a large range of frequencies with corresponding linear increase in tan (δ) values. We relate the enhanced performance of dPEDOT with the underlying structural constituents using FTIR and AFM microscopy. These data demonstrate specific interactions between individual components of dPEDOT, their effect on surface topography and material properties. Finally, 20 we show biocompatibility of dPEDOT using fibroblasts that have comparable cell morphologies and viability as control; making it attractive as a biomaterial. 65 Hookean (NH) form of hyperelastic constitutive model, given by = ( 1 2 + 2 2 + 3 2 − 3) where ; = 1: 3 are stretches in the principal directions respectively. These experimental data

Landing on vertical surfaces in challenging environments is a critical ability for multimodal robots—it allows the robot to hold position above the ground without expending energy to hover. Asian flat‐tailed geckos (Hemidactylus platyurus) are observed to glide and perch on vertical surfaces by relying on their tail and body morphology, potentially reducing the control effort to perch. This novel perching mechanism using a bioinspired physical model is discussed and its tail and body parameters to determine their influence on perching success and the kinematics of the gecko's dynamic landing maneuver are adjusted. Perching performance is evaluated by changing the model's torso and tail stiffness. Combining a compliant torso and stiff tail enables the model to passively perch on a vertical substrate with a success rate >90%, compared with ≈10% without a tail attached. A compliant torso is necessary to absorb the in‐flight kinetic energy and accommodate the uncertainties in approach conditions. Similar to the gecko's perching strategy, the stiff tail pushes against the substrate, preventing the model from falling backward head over heels. These findings highlight the critical role of tail and material stiffness for perching and provide a simplified mechanism to impart perching capabilities in robots.

Studies invoking biomitetics have gained significant popularity over the last two decades, allowing for the construction of more lifelike robots inspired by nature. The goal of bioinspired robotics is often twofold: understanding nature's fundamental processes and acquiring the capacity to replicate those processes to ultimately construct improved robotic platforms with similar capability. By examining the underlying principles of locomotion strategies found in nature, researchers sought to develop robots with similar capabilities in aerial, [1,2] aquatic, [3][4][5][6][7][8] and terrestrial [9][10][11][12] environments as well as using the robots as platforms in biomechanics research to understand the fundamentals of animal locomotion. [13] To negotiate compelx environments and flow regimes, animals must be able to perform multimodal locomotion. Highly maneuverable multimodal locomotion is needed for diverse survival needs such as fast escape from predators, quick pursuit, searching for food, breeding, nesting, preserving energy, and migration. [14] The most delicate aspect of multimodal locomotion is the challenging transition from one mode to another at the intersection land-air, water-air, or water-land. Flying and gliding animals transition from air to land by perching on a diverse range of complex, natural, and surfaces. [15] From large birds to microscopic insects, animals rely mostly on passive mechanisms to perch. Birds decelerate in the air utilizing their morphing wings and tail and then land slowly in a controlled fashion as they approach the substrate. During landing, they bend their legs, resulting in a tendon on the ankle's backside to naturally force the toes to grip around a branch. This passively operated mechanism is critical for perching without active gripping control. [16,17] Smaller animals also depend on the functional morphology to increase robustness and reduce neural control effort honeybees use the swinging motion of their abdomen to dissipate residual flying energy to achieve a smooth, stable, and quick landing. [18] Houseflies perch by using their compliant legs to dissipate the high kinetic energy of flight. [19] Perching is not limited to flight animals. Gliding animals in the absence of thrust generation capabilities can also modify their body orientation and body shape to successfully perch. [20][21][22][23] Gliding mammals and flying lizards possess well-defined aerodynamic surfaces allowing them to significantly decelerate their descent and control their body orientation before perching. [24]

This review highlights the largely understudied behavior of gliding locomotion, which is exhibited by a diverse range of animals spanning vertebrates and invertebrates, in air and in water. The insights in the literature gained from January 2022 to December 2022 continue to challenge the previously held notion of gliding as a relatively simple form of locomotion. Using advances in field/lab data collection and computation, the highlighted studies cover gliding in animals including seabirds, flying lizards, flying snakes, geckos, dragonflies, damselflies, and dolphins. Altogether, these studies present gliding as a sophisticated behavior resulting from the interdependent aspects of morphology, sensing, environment, and likely selective pressures. This review uses these insights as inspiration to encourage researchers to revisit gliding locomotion, both in the animal's natural habitat and in the laboratory, and to investigate questions spanning gliding biomechanics, ecology, sensing, and the evolution of animal flight.

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