Mode Of Locomotion Research Articles

Mechanical model and experimental investigation of a novel pneumatic foot

Almost all forms of soft crawling robots and animals rely on frictional anisotropy to achieve terrestrial locomotion. However, the electroadhesion force of actuators is limited to the materials, roughness of various terrain, and patterning high- and low- friction materials on the ventral side of the robot can only enable the robot to crawl along a single direction. This paper presents a novel pneumatic foot that can regulate the friction between itself and the crawling surface to achieve frictional anisotropy in two opposite directions. The design scheme, working mechanism and analytical model based on the energy method of the pneumatic foot are described. The accuracy of the analytical model is verified by numerical simulation and experimental study. A soft crawling robot, including its locomotion mode and control system, is designed. Crawling experiments on various terrain and payload experiments are conducted to prove the feasibility of the pneumatic foot. The pneumatic foot can enable the robot to crawl on various terrain at a maximum speed of 0.128 BL/s. When the payloads are 4.29 times of the robot’s weight, the crawling speed is still relatively high (0.108 BL/s). This pneumatic foot can be applied to biomimetic inchworm or earthworm robots on various terrain and in some limited space, such as the air ducts of central air-conditioning.

Exocrine gland-resident memory CD8+ T cells use mechanosensing for tissue surveillance.

Tissue-resident CD8+ T cells (TRM) continuously scan peptide-MHC (pMHC) complexes in their organ of residence to intercept microbial invaders. Recent data showed that TRM lodged in exocrine glands scan tissue in the absence of any chemoattractant or adhesion receptor signaling, thus bypassing the requirement for canonical migration-promoting factors. The signals eliciting this noncanonical motility and its relevance for organ surveillance have remained unknown. Using mouse models of viral infections, we report that exocrine gland TRM autonomously generated front-to-back F-actin flow for locomotion, accompanied by high cortical actomyosin contractility, and leading-edge bleb formation. The distinctive mode of exocrine gland TRM locomotion was triggered by sensing physical confinement and was closely correlated with nuclear deformation, which acts as a mechanosensor via an arachidonic acid and Ca2+ signaling pathway. By contrast, naïve CD8+ T cells or TRM surveilling microbe-exposed epithelial barriers did not show mechanosensing capacity. Inhibition of nuclear mechanosensing disrupted exocrine gland TRM scanning and impaired their ability to intercept target cells. These findings indicate that confinement is sufficient to elicit autonomous T cell surveillance in glands with restricted chemokine expression and constitutes a scanning strategy that complements chemosensing-dependent migration.

The sedimentation behaviors of elliptical active particles in a rectangular box

The “squirmer” model, a micro-swimming model driven by an imposed tangential velocity at the boundaries, is used to simulate the sedimentation behaviors of one and two elliptical active particles in a two-dimensional rectangular box. Six typical locomotion modes (including the steady vertically moving (SVM), steady inclined sliding (SIS), unilateral attracted oscillating (UAO), bilateral attracted oscillating (BAO), chaotic attracted oscillating (CAO), and up-down alternate tumbling (UAT)) are identified. The effects of particle aspect ratio (AR = 0.2∼1.0), self-propelling strength (β = −5∼5), swimming Reynolds number (Res = 0.1∼5.0), and density ratio of particle to fluid (γ = 1.01∼2.1) on the sedimentation behaviors of particles (the locomotion modes and the terminal Reynolds number (Ret)), are discussed. It is concluded that the locomotion modes are closely relevant to AR, γ, and Res. The collision between particles only changes their orientations but is not sensitive to the final locomotion modes. At Res≥4.0, the modes of puller type particles change from UAO to SIS or SIS to UAT. Meanwhile, it is found that (ⅰ) particle's Ret increases with AR when it is in SIS; a larger AR leads to a greater decay of Ret when it is in UAO; the decay of Ret is smooth when it is in BAO. (ⅱ) A large |β| results in a large Ret for a particle in SIS, and it is more prominent for a puller type particle than a pusher type particle. (ⅲ) In the falling period, Res speeds up a pair of pusher type particles, while it is more prominent for the pusher type particle with a lower initial position; Res also speeds up both neutral type particles with a linear relationship of Ret∼1.35Res. γ and Ret are linear positive correlated for both a pair of pusher type particles and a pair of neutral type particles.

Sex and State-Dependent Effects on Proactive Behaviors of Bent-Wing Bats Across Contexts

Synopsis Animals within a population may show distinct behavioral types that differ consistently among individuals over time and across contexts, collectively known as animal personality. Individual state variables arising from intrinsic features of organisms and their interactions with the environment may contribute to or aid in maintaining these interindividual behavioral differences. The present study examined the effects of body mass, body condition, flight morphology, and parasite load on the personality traits of bent-wing bats Miniopterus fuliginosus. We assessed the bats in three testing contexts—hole-board box (HB), tunnel-box (TB), and flight-tent (FT)—that mimicked their natural environmental settings and allowed for different locomotion modes. A principal component analysis loaded the three mutually positively correlated personality traits of the bats—boldness, activity, and exploration—in each context onto a single component of proactiveness. In accordance with the AIC criteria, sex, body mass, body condition index, and wingtip shape were selected as predictors for the proactiveness of the bats in the TB and FT tests. In the HB tests, the biomass and abundances of parasitic bat flies were additionally selected, but body condition was excluded. We found a negative effect of the body mass on the proactiveness of the female bats in both the HB and FT tests, and that on the proactiveness of the male bats in the HB tests but not so in the FT tests. The sexual differences and negative correlation between the body mass of the bats and their proactive responsiveness are consistent with the mechanism of state-dependent energy assimilation efficiency. Our results may also concur with the predicted feedback mechanism stemming from the characteristic conditions associated with the environment of the bats. This latter inference offers insights for exploring the patterns of personality traits along gradients or the seasonality of ecological conditions.

Does aquatic performance predict terrestrial performance: a case study with an aquatic frog, Xenopus laevis.

The physical properties of the environment impose strong selection on organisms and their form-function relationships. In water and on land, selective pressures differ, with water being more viscous and denser than air, and gravity being the most important external force on land for relatively large animals such as vertebrates. These different properties of the environment could drive variation in the design and mechanics of the locomotor system of organisms. Animals that use multiple environments can consequently exhibit locomotion conflicts between the demands imposed by the media, leading to potential trade-offs. Here, we tested for the presence of such locomotor trade-offs depending on the environment (water or land) in a largely aquatic frog, Xenopus laevis. We focused on terrestrial and aquatic exertion capacity (time and distance swum or jumped until exhaustion) and aquatic and terrestrial burst capacity (maximal instantaneous swimming velocity and maximal force jump) given the ecological relevance of these traits. We tested these performance traits for trade-offs, depending on environments (water versus air) and locomotor modes (i.e. exertion and burst performance). Finally, we assessed the contribution of morphological traits to each performance trait. Our data show no trade-offs between the performance traits and between the environments, suggesting that X. laevis is equally good at swimming and jumping thanks to the same underlying morphological specialisations. We did observe, however, that morphological predictors differed depending on the environment, with variation in head shape and forelimb length being good predictors for aquatic locomotion and variation in hindlimb and forelimb segments predicting variation in jumping performance on land.

Bio-Inspired Untethered Robot-Sensor Platform for Minimally Invasive Biomedical Sensing.

Conventional catheter- or probe-based in vivo biomedical sensing is uncomfortable, inconvenient, and sometimes infeasible for long-term monitoring. Existing implantable sensors often require an invasive procedure for sensor placement. Untethered soft robots with the capability to deliver the sensor to the desired monitoring point hold great promise for minimally invasive biomedical sensing. Inspired by the locomotion modes of snakes, we present here a soft kirigami robot for sensor deployment and real-time wireless sensing. The locomotion mechanism of the soft robot is achieved by kirigami patterns that offer asymmetric tribological properties that mimic the skin of the snake. The robot exhibits good deployability, excellent load capacity (up to 150 times its own weight), high-speed locomotion (0.25 body length per step), and wide environmental adaptability with multimodal movements (obstacle crossing, locomotion in wet and dry conditions, climbing, and inverted crawling). When integrated with passive sensors, the versatile soft robot can locomote inside the human body, deliver the passive sensor to the desired location, and hold the sensor in place for real-time monitoring in a minimally invasive manner. The proof-of-concept prototype demonstrates that the platform can perform real-time impedance monitoring for the diagnosis of gastroesophageal reflux disease.

3D Printable Micro/Macro Dual Driving Multipede Millirobot and Its Characterization for Multi-Locomotory Modes

Aiming at both high motion precision and high velocity is arduous in the development of miniature robots because of contradictory aspects between the precision and the velocity. In this article, we developed a simple three-dimensional printable micro/macro dual driving multipede millirobot to successfully satisfy both high precision and high velocity, by employing bio-inspired titled legs through the concept of anisotropic friction. Four locomotory modes (stick, stick-slip, pure-slip, and jumping) of the millirobot were carefully examined and effectively manipulated to switch micro and macro motions for high precision and high velocity, respectively. We investigated the effects of external conditions (mobile surface roughness and excitation waveform) and internal conditions (geometric parameters of driving legs) on the locomotory modes. The millirobot achieved a step resolution of 2 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> m in the micromotion and maximum mobile velocity of 800 mm/s in the macromotion. In addition, our millirobot can perform bi-directional motion (forward and backward) with quick return characteristics.

How birds dissipate heat before, during and after flight.

Animal flight uses metabolic energy at a higher rate than any other mode of locomotion. A relatively small proportion of the metabolic energy is converted into mechanical power; the remainder is given off as heat. Effective heat dissipation is necessary to avoid hyperthermia. In this study, we measured surface temperatures in lovebirds (Agapornis personatus) using infrared thermography and used heat transfer modelling to calculate heat dissipation by convection, radiation and conduction, before, during and after flight. The total non-evaporative rate of heat dissipation in flying birds was 12× higher than before flight and 19× higher than after flight. During flight, heat was largely dissipated by forced convection, via the exposed ventral wing areas, resulting in lower surface temperatures compared with birds at rest. When perched, both before and after exercise, the head and trunk were the main areas involved in dissipating heat. The surface temperature of the legs increased with flight duration and remained high on landing, suggesting that there was an increase in the flow of warmer blood to this region during and after flight. The methodology developed in this study to investigate how birds thermoregulate during flight could be used in future studies to assess the impact of climate change on the behavioural ecology of birds, particularly those species undertaking migratory flights.

Environmental force sensing helps robots traverse cluttered large obstacles

Robots can traverse sparse obstacles by sensing environmental geometry and avoiding contact with obstacles. However, for search and rescue in rubble, environmental monitoring through dense vegetation, and planetary exploration over Martian and lunar rocks, robots must traverse cluttered obstacles as large as themselves by physically interacting with them. Previous work discovered that the forest floor-dwelling discoid cockroach and a sensor-less minimalistic robot can traverse cluttered grass-like beam obstacles of various stiffness by transitioning across different locomotor modes. Yet the animal was better at traversal than the sensor-less robot, likely by sensing forces during obstacle interaction to control its locomotor transitions. Inspired by this, here we demonstrated in simulation that environmental force sensing helps robots traverse cluttered large obstacles. First, we developed a multi-body dynamics simulation and a physics model of the minimalistic robot interacting with beams to estimate beam stiffness from the sensed contact forces. Then, we developed a force feedback strategy for the robot to use the sensed beam stiffness to choose the locomotor mode with a lower mechanical energy cost. With feedforward pushing, the robot was stuck in front of stiff beams if it has a limited force capacity; without force limit, it traversed but suffered a high energy cost. Using obstacle avoidance, the robot traversed beams by avoiding beam contact regardless of beam stiffness, resulting in a high energy cost for flimsy beams. With force feedback, the robot determined beam stiffness, then traversed flimsy beams by pushing them over and stiff beams by rolling through the gap between them with a low energy cost. Stiffness estimation based on force sensing was accurate across varied body oscillation amplitude and frequency and position sensing uncertainty. Mechanical energy cost of traversal increased with sensorimotor delay. Future work should demonstrate cluttered large obstacle traversal using force feedback in a physical robot.

The development of a novel terrestrial/aerial robot: autonomous quadrotor tilting hybrid robot

AbstractUnmanned aerial vehicles (UAVs) possess fast-moving abilities and have been used in various tasks in the past decades. However, their performances are still restricted by insufficient endurance and confined environments. Intuitively, combining other locomotion modes with UAVs, such as diving and driving, would be an appropriate idea to improve the robot’s adaptability and solve the endurance problem. Recently, the terrestrial/aerial hybrid robots have drawn the researchers’ eyes for their outstanding performances, which can deploy flight mode to traverse insurmountable terrains and ground mode to increase endurance and realize detailed searches. Therefore, this paper developed the autonomous quadrotor tilting hybrid robot (AQT-HR) to achieve terrestrial/aerial dual-modal mobility and verified that the robot delivers high energy efficiency. The AQT-HR can achieve flying and driving through a quadrotor tilting mechanism, which can alter one single driving force into different directions. Furthermore, the dynamic models of the hybrid robot’s aerial and ground locomotion are derived and introduced into the model-feedforward PID control algorithm for improving the robot’s flying stability. Finally, we conducted some mobility tests and experiments about traversing obstacles to demonstrate that the proposed hybrid robot can realize autonomous mode switching and perform a low energy consumption in ground movement mode.

Quadrupedal terrestrial locomotion in emperor penguins (Aptenodytes forsteri)

ABSTRACT Birds generally employ bipedal terrestrial locomotion; their wings flap synchronously to provide aerial propulsion. Penguins (Spheniscidae) are non-flyers that use their modified wings (flippers) to ‘fly’ underwater, again using synchronous action. The family is distributed from the equator to the Antarctic; the earliest penguins lived at temperate latitudes. On land, penguins usually walk bipedally and slowly (waddling) because their legs are short and their bodies long and fusiform. Their flippers are held out sideways and show little movement; they may function like balance poles. A few penguin species breed at high latitude and make substantial terrestrial migrations over snow and ice; they intermittently use an alternative terrestrial locomotory mode (tobogganing) in which they lie on their ventral surfaces and use the feet alternately to propel them more quickly. The emperor penguin Aptenodytes forsteri makes two-way trips (<250 km) to breed, encountering both ice and several types of snow. The topography varies from flat areas to steep slopes and ridges. In this study we analysed 13 publicly available video records and demonstrate that the flippers are also used for propulsion (particularly for climbing in deep snow). Gait analysis reveals that all four limbs are employed in a quadrupedal, ipsilaterally coordinated manner: the classic mode of tetrapod terrestrial locomotion. During climbing, tetrapod limb action is supplemented by use of the beak as an anchor. During quadrupedal locomotion over snow the flippers move snow on their power strokes, thereby demonstrating exchange of forces.

Early Prediction of Lower Limb Prostheses Locomotion Mode Transition Based on Terrain Recognition

Early Prediction of Lower Limb Prostheses Locomotion Mode Transition Based on Terrain Recognition

Toward Real-Time Animal Tracking with Integrated Stimulus Control for Automated Conditioning in Aquatic Eco-Neurotoxicology.

Aquatic eco-neurotoxicology is an emerging field that requires new analytical systems to study the effects of pollutants on animal behaviors. This is especially true if we are to gain insights into one of the least studied aspects: the potential perturbations that neurotoxicants can have on cognitive behaviors. The paucity of experimental data is partly caused by a lack of low-cost technologies for the analysis of higher-level neurological functions (e.g., associative learning) in small aquatic organisms. Here, we present a proof-of-concept prototype that utilizes a new real-time animal tracking software for on-the-fly video analysis and closed-loop, external hardware communications to deliver stimuli based on specific behaviors in aquatic organisms, spanning three animal phyla: chordates (fish, frog), platyhelminthes (flatworm), and arthropods (crustacean). The system's open-source software features an intuitive graphical user interface and advanced adaptive threshold-based image segmentation for precise animal detection. We demonstrate the precision of animal tracking across multiple aquatic species with varying modes of locomotion. The presented technology interfaces easily with low-cost and open-source hardware such as the Arduino microcontroller family for closed-loop stimuli control. The new system has potential future applications in eco-neurotoxicology, where it could enable new opportunities for cognitive research in diverse small aquatic model organisms.

High-density EMG, IMU, kinetic, and kinematic open-source data for comprehensive locomotion activities

Novel sensor technology enables new insights in the neuromechanics of human locomotion that were previously not possible. Here, we provide a dataset of high-density surface electromyography (HDsEMG) and high-resolution inertial measurement unit (IMU) signals, along with motion capture and force data for the lower limb of 10 healthy adults during multiple locomotion modes. The participants performed level-ground and slope walking, as well as stairs ascent/descent, side stepping gait, and stand-to-walk and sit-to-stand-to-walk, at multiple walking speeds. These data can be used for the development and validation of locomotion mode recognition and control algorithms for prosthetics, exoskeletons, and bipedal robots, and for motor control investigations.

The impact of the land-to-sea transition on evolutionary integration and modularity of the pinniped backbone

In this study, we investigate how the terrestrial-aquatic transition influenced patterns of axial integration and modularity in response to the secondary adaptation to a marine lifestyle. We use 3D geometric morphometrics to quantify shape covariation among presacral vertebrae in pinnipeds (Carnivora; Pinnipedia) and to compare with patterns of axial integration and modularity in their close terrestrial relatives. Our results indicate that the vertebral column of pinnipeds has experienced a decrease in the strength of integration among all presacral vertebrae when compared to terrestrial carnivores (=fissipeds). However, separate integration analyses among the speciose Otariidae (i.e., sea lions and fur seals) and Phocidae (i.e., true seals) also suggests the presence of different axial organizations in these two groups of crown pinnipeds. While phocids present a set of integrated “thoracic” vertebrae, the presacral vertebrae of otariids are characterized by the absence of any set of vertebrae with high integration. We hypothesize that these differences could be linked to their specific modes of aquatic locomotion –i.e., pelvic vs pectoral oscillation. Our results provide evidence that the vertebral column of pinnipeds has been reorganized from the pattern observed in fissipeds but is more complex than a simple “homogenization” of the modular pattern of their close terrestrial relatives.

Neuroanatomy of the late Cretaceous Thescelosaurus neglectus (Neornithischia: Thescelosauridae) reveals novel ecological specialisations within Dinosauria

Ornithischian dinosaurs exhibited a diversity of ecologies, locomotory modes, and social structures, making them an ideal clade in which to study the evolution of neuroanatomy and behaviour. Here, we present a 3D digital reconstruction of the endocranial spaces of the latest Cretaceous neornithischian Thescelosaurus neglectus, in order to interpret the neuroanatomy and paleobiology of one of the last surviving non-avian dinosaurs. Results demonstrate that the brain of Thescelosaurus was relatively small compared to most other neornithischians, instead suggesting cognitive capabilities within the range of extant reptiles. Other traits include a narrow hearing range, with limited ability to distinguish high frequencies, paired with unusually well-developed olfactory lobes and anterior semicircular canals, indicating acute olfaction and vestibular sensitivity. This character combination, in conjunction with features of the postcranial anatomy, is consistent with specializations for burrowing behaviours in the clade, as evidenced by trace and skeletal fossil evidence in earlier-diverging thescelosaurids, although whether they reflect ecological adaptations or phylogenetic inheritance in T. neglectus itself is unclear. Nonetheless, our results provide the first evidence of neurological specializations to burrowing identified within Ornithischia, and non-avian dinosaurs more generally, expanding the range of ecological adaptations recognized within this major clade.

A Small-Scale Untethered Tensegrity Robot With High Velocity and Multi Locomotion Modes

A Small-Scale Untethered Tensegrity Robot With High Velocity and Multi Locomotion Modes

Acoustic Streaming-Induced Multimodal Locomotion of Bubble-Based Microrobots.

Acoustically-driven bubbles at the micron scale can generate strong microstreaming flows in its surrounding fluidic medium. The tunable acoustic streaming strength of oscillating microbubbles and the diversity of the generated flow patterns enable the design of fast-moving microrobots with multimodal locomotion suitable for biomedical applications. The acoustic microrobots holding two coupled microbubbles inside a rigid body are presented; trapped bubbles inside the L-shaped structure with different orifices generatevarious streaming flows, thus allowing multiple degrees of freedom in locomotion. The streaming pattern and mean streaming speed depend on the intensity and frequency of the acoustic wave, which can trigger four dominant locomotion modes in the microrobot, denoted as translational and rotational, spinning, rotational, and translational modes. Next, the effect of various geometrical and actuation parameters on the control and navigation of the microrobot is investigated. Furthermore, the surface-slipping multimodal locomotion, flow mixing, particle manipulation capabilities, the effective interaction of high flow rates with cells, and subsequent cancerous cell lysing abilities of the proposed microrobot are demonstrated. Overall, these results introduce a design toolbox for the next generation of acoustic microrobots with higher degrees of freedom with multimodal locomotion in biomedical applications.

Spikebot: A Multigait Tensegrity Robot with Linearly Extending Struts.

Numerous recent research efforts have leveraged networks of rigid struts and flexible cables, called tensegrity structures, to create highly resilient and packable mobile robots. However, the locomotion of existing tensegrity robots is limited in terms of both speed and number of distinct locomotion modes, restricting the environments that a robot is capable of exploring. In this study, we present a tensegrity robot inspired by the volumetric expansion of Tetraodontidae. The robot, referred to herein as Spikebot, employs pneumatically actuated rigid struts to expand its global structure and produce diverse gaits. Spikebot is composed of linear actuators that dually serve as rigid struts linked by elastic cables for stability. The linearly actuating struts can selectively protrude to initiate thrust- and instability-driven locomotion primitives. Such motion primitives allow Spikebot to reliably locomote, achieving rolling, lifting, and jumping. To highlight Spikebot's potential for robotic exploration, we demonstrate how it achieves multi-dimensional locomotion over varied terrestrial conditions.

Kinematic Modeling and Optimization of a Clustered Tensegrity Mobile Robot

Abstract Clustered tensegrity mechanisms have elicited extensive attention in recent research due to their easy control system and high stiffness-to-mass ratio. However, modeling and analyzing these mechanisms are still challenging due to the clustering of cables and redundant structural parameters. This article proposes an energy-based kinematic modeling method for a modular clustered tensegrity mobile robot. The design of the clustered tensegrity robot is inspired by the biomechanics of worms, allowing it to achieve two locomotion modes resembling earthworm-like and inchworm-like movements using two motors. Moreover, the clustered and modular structure enables the robot to increase the number of modules as needed without increasing the number of actuators. This feature enhances the robot's terrain adaptability without adding complexity to the control system. The article establishes kinematic models using the energy method and clarifies the motion law of nodes on the sliding cables of the robot, considering multiple structural parameters for both locomotion modes. Based on these models, the article reveals the mapping relationships among various structural parameters (i.e., cable-hole gap, cable-hole friction, stiffness and original length of elastic cables, and ground–robot friction) and locomotion performance (i.e., morphology, displacement, and velocity) of the robot. Furthermore, structural parameter optimization is performed to enhance the kinematic performance of the robot in both locomotion modes simultaneously. To validate the proposed kinematic modeling method, a prototype with two modules is developed, and experiments are conducted to assess the robot's locomotion performance. These experiments demonstrate the effectiveness and rationality of the proposed method.