Locomotion Velocity Research Articles

Laser-Printed All-Carbon Responsive Material and Soft Robot.

Responsive materials and actuators are the basis for the development of various leading-edge technologies but have so far mostly been designed based on polymers, incurring key limitations related to sensitivity and environmental tolerance. This work reports a new responsive material, laser-printed carbon film (LPCF), produced via direct laser transformation of a liquid organic precursor and consists of graphitic and amorphous carbons. The high activity of amorphous carbon combined with the dual-gradient structure enables the LPCF to have a actuation speed of 9400°s-1 in response to the stimulus of organic vapor. LPCF exhibits a conductivity of 950Sm-1 and excellent resistance to various extreme environmental conditions, which are unachievable for polymer-based materials. Additionally, an LPCF-based all-carbon soft robot that can mimic the complex continuous backward somersaulting motions without manual intervention is constructed. The locomotion velocity of the robot reaches a value of 1.19BLs-1, which is almost one to two orders of magnitude faster than that of reported soft robots. This work not only offers a new paradigm for highly responsive materials but also provides a great design and engineering example for the next generation of biomimetic robots with life-like performance.

Higher Blood Lactate with Prolongation of Underwater Section in Submaximal Front-Crawl Swimming.

The underwater phase (UP) is highly important for overall swimming performance in most swimming events. However, the metabolic effects of the prolonged UP remain unclear. The purpose of this cross-sectional study was to compare the blood lactate response to submaximal front-crawl swimming with short and extended UP. Twelve (four females) junior competitive swimmers (aged 15.4 (1.4) years) undertook 200 m front-crawl swim trials in a 25 m pool at a pre-determined "anaerobic threshold" velocity on two occasions using short (<5 m) and extended (12.5 m) UP after each turn. Pacing and total time were ensured to be identical between the trials. Capillary blood lactate response was measured. Testing for 25 m swim time with <5 m and 12.5 m UP was conducted on a separate occasion. When athletes undertook and extended UP after each propulsion from the wall, their post-exercise blood lactate concentration reached 7.9 (2.1) mmol/L, more than two times higher than the response to trial with short UP (p < 0.001). All-out 25 m swimming with <5 m or 12.5 m UP disclosed no difference in locomotion velocity (p > 0.05). In conclusion, extending UP of submaximal front-crawl swimming close to maximally allowed during the races substantially increases blood lactate accumulation, i.e., increases the reliance on anaerobic metabolism. Therefore, extended UP is most likely counterproductive for the performance in long-distance swimming, at least for the athletes with a FINA score of <800. On the other hand, the extension of UP could be an effective strategy to train 'lactate tolerance', lactate shuttling, removal, and recycling.

Locomotor-cognitive dual-tasking in children with developmental coordination disorder.

Children with Developmental Coordination Disorder (DCD) demonstrate deficits in predictive motor control and aspects of cognitive control compared with their typically developing (TD) peers. Adjustment to dynamic environments depends on both aspects of control and the deficits for children with DCD may constrain their ability to perform daily actions that involve dual-tasking. Under the assumption that motor-cognitive integration is compromised in children with DCD, we examined proportional dual-task costs using a novel locomotor-cognitive dual-task paradigm that enlisted augmented reality. We expect proportional dual-task performance costs to be greater for children with DCD compared to their TD peers. Participants were 34 children aged 6-12 years (16 TD, 18 DCD) who walked along a straight 12 m path under single- and dual-task conditions, the cognitive task being visual discrimination under simple or complex stimulus conditions presented via augmented reality. Dual-task performance was measured in two ways: first, proportional dual-task costs (pDTC) were computed for cognitive and gait outcomes and, second, within-trial costs (p-WTC) were measured as the difference on gait outcomes between pre- and post-stimulus presentation. On measures of pDTC, TD children increased their double-limb support time when walking in response to a dual-task, while the children with DCD increased their locomotor velocity. On p-WTC, both groups increased their gait variability (step length and step width) when walking in response to a dual-task, of which the TD group had a larger proportional change than the DCD group. Greater pDTCs on motor rather than cognitive outcomes were consistent across groups and method of dual-task performance measurement. Contrary to predictions, our results failed to support dramatic differences in locomotor-cognitive dual-task performance between children with DCD and TD, with both groups tending to priorities the cognitive over the motor task. Inclusion of a within-trial calculation of dual-task interference revealed an expectancy effect for both groups in relation to an impending visual stimulus. It is recommended that dual-task paradigms in the future continue to use augmented reality to present the cognitive task and consider motor tasks of sufficient complexity to probe the limits of performance in children with DCD.

Thermally-activated locomotion of a bilayer polymer actuator

The development of smart actuators based on renewable or biocompatible materials, which are able for delivery of specific cargo is of great importance in robotics, medical and material science engineering, food industry, etc. Here, we report the original design of a bilayer polymer actuator consisting of two polymer materials with an interface adhesive layer between them, able for macroscopic locomotion step by step on a special ratchet substrate through repetitive bending and straightening. This was triggered by heat alternation due to incandescent lamp radiation on/off switching, with a rapid reaction time of the actuator to heat exposure of the order of few seconds. Specifically, a relatively fast locomotion of the actuator was achieved due to the large amplitude of its reversible bending deformation of up to ∼40% measured in terms of the actuator's elevation-to-length ratio. As a result, a typical actuator demonstrated the locomotion velocity of about 3 cm/min, where each cycle of contraction/expansion yielded a walking step of ∼1 cm for about 20 s. It was demonstrated that the actuator, while moving, is able to carry a cargo almost twice heavier than the mass of the carrier itself. Based on optical microscopy and atomic force - infrared spectroscopy data it was concluded that the adhesive interface layer plays an important role in the stable operation of the actuator as it retards linear expansion of the rear polymer layer and thus assists conversion of different linear expansion of the adjacent layers into their effective bending.

Alligatorascension: climbing performance of Alligator mississippiensis

Abstract In tetrapedal locomotion, whether horizontal or during climbing, interactions between the foot and the contact surface or substrate influence the locomotor performance. Multiple previous studies of tetrapedal squamates (lizards) have reported that the animals used the same locomotor velocity, regardless of the angle of ascension. The present study was performed to determine if the American alligator (Alligator mississippiensis) would exhibit a stable climbing velocity and to determine to what degree, if any, this climbing velocity could be modified by substrate differences. Sub-adult Alligator mississippiensis, with body lengths around 170 cm, used the same stride velocity when moving at angles of 0°, 30°, and 55°. During these trials, both the sub-adult and juvenile alligators used a “low walk” gait, rather than a distinctive climbing gait. When the alligators traversed an open grate, their stride duration increased (and stride velocity decreased) presumably due to the insertion (and retraction) of their claws and digits into the grate. When climbing at 55° the juvenile and sub-adult alligators used the same stride duration; the sub-adults used a stride length that was significantly larger in absolute terms, but significantly shorter in relative terms. Despite their large size, and their more caudal center of mass, the climbing performance of Alligator mississippiensis is similar to what has been described in the previously-studied tetrapedal squamates.

Neurotoxicity of Glyphosate to Planarian Dugesia japonica.

As one of the most widely used herbicides in agricultural industry, the residues of glyphosate (GLY) are frequent environmental pollutants. Freshwater planarian Dugesia japonica has been developed as a model for neurotoxicology. In this study, the effects of GLY on locomotion and feeding behavior, as well as neuroenzyme activities and mRNA expressions of D. japonica were determined. Additionally, histochemical localization was executed to explore the damage to the central nervous system (CNS) of planarians stressed by GLY. The results showed that the locomotor velocity, ingestion rate and the neuroenzyme activity were inhibited and the gene expressions were altered. Also, histo-architecture injury to CNS of planarians upon GLY exposure in a time-dependent manner was observed. Collectively, our results indicate that GLY can cause neurotoxicity to freshwater planarians representing as reduction in locomotor velocity and feeding rate by disturbing the neurotransmission systems and damaging the structure of CNS.

A magnetic soft robot with rolling and grasping capabilities

Soft robots offer a great application potential in the field of military, medical, and industry. In this study, a rolling gait was adopted to the design of the soft robot so as to improve the locomotion velocity of the soft robot actuated by the magnetic field. The soft robot was fabricated as a square frame structure (6 × 6 × 0.6 mm) to achieve grasping function. The experimental results indicated that the designed soft robot could roll on a slope with a maximum inclination around 30° under the given conditions. The velocity of the soft robot during the rolling process would decrease with the increase of the inclination. Meanwhile, the soft robot could carry objects 3.75 times its own weight when it rolled on a level pavement. Further analysis and experiments suggested that the rolling locomotion of the soft robot relied on the magnetic torque and the friction force. The locomotion velocity of the soft robot was related to the perimeter of the contour composed of the soft robot and the object being grasped. Moreover, a modular assembly strategy was proposed to improve the locomotion and grasping performance of the soft robot. The findings of this work will help to promote the application of untethered soft robots.

Responses of Freshwater Planarian Girardia tigrina to Fipronil-Based Insecticide: Survival, Behavioral and Physiological Endpoints

Fipronil is a pyrazole insecticide used to control undesirable insect populations. Due to its large-scale application, there is the potential for surface waters’ contamination, with toxic action for non-target organisms, and consequent impacts on aquatic ecosystems. Planarians are potential non-target aquatic invertebrates to these insecticides. They are widespread in tropical freshwaters and have been proposed as good candidates to assess the toxic effects of freshwater systems contaminated by insecticides. Thus, the present study aims to evaluate the sublethal concentrations of a fipronil-based insecticide that may affect the planarian physiology. After chronic exposure to Regent 800 WG®, a significant decrease in locomotor velocity (LOEC—6.25 mg·L−1), regeneration of the auricles and photoreceptors (LOEC—3.13 mg·L−1), and reproduction (fecundity—LOEC 12.5 mg·L−1) were observed. The results of our study demonstrate that long-term exposure to a pyrazole insecticide can compromise non-target aquatic invertebrates while reinforcing the need for a better investigation of complementary parameters (such as behavior, regeneration, and reproduction) for a more accurate risk assessment of commercial pesticide toxicity in freshwater systems.

Leveraging Evolutionary Algorithms for Feasible Hexapod Locomotion Across Uneven Terrain

Optimizing gait stability for legged robots is a difficult problem. Even on level surfaces, effectively traversing across different textures (e.g., carpet) rests on dynamically tuning parameters in multidimensional space. Inspired by biology, evolutionary algorithms (EA) remain an attractive solution for feasibly implementing robotic locomotion with both energetic economy and rapid parameter convergence. Here, we leveraged this class of algorithms to evolve a stable hexapod gait controller capable of traversing uneven terrain and obstacles. Gait parameters were evolved in a rigid body dynamics simulation on an 8 x 3 meter obstacle course comprised of random step field, linear obstacles and inclined surfaces. Using a fitness function that jointly optimized locomotion velocity and stability, we found that multiple successful gait parameter evolutions yielded specialized functionality for each leg. Specific gait parameters were identified as critical to developing a rough terrain gait.

Coordinated optimization of locomotion velocity and energy consumption in vibration-driven system

Coordinated optimization of locomotion velocity and energy consumption in vibration-driven system

Optimal control of the multi-module vibration-driven locomotion robot

The vibration-driven robot utilizes the periodic inertia force from the oscillator to realize locomotion. Because its movement does not rely on wheels or legs, the robot's body can be designed very neatly for working in restricted circumstances such as pipeline inspection and post-disaster rescue. Because high mobility is essential in these applications, the issue of actuation design to maximize the robot's average locomotion velocity emerges. Distinct from parameter optimization at given actuation patterns, the present paper represents the actuation design as the problem of optimal control and constructs an evolutionary algorithm to solve it. First, taking advantage of the periodicity, the internal actuation is represented as the Fourier series with the unknown period, harmonic coefficients, and phase shifts. Then, the multi-objective evolutionary algorithm based on decomposition (MOEA/D) is employed to optimize the unknown multi-parameters. Numerical results show that the optimal actuation of the one-module robot with isotropic friction is consistent with existing theoretical solutions, which verifies the correctness and practicability of our general scheme. Further explorations of the multi-module robot reveal that the optimal actuation continuously degenerates from the three-phase pattern to the two-phase when the friction ratio gradually attenuates to zero. Most importantly, although the optimal actuation phase shift between adjacent robot modules has been commonly accepted as half of the actuation period, the proposed scheme finds that the average velocity indeed maintains the maximum within a certain phase margin. As can be expected, this robustness will relax the burden of sophisticated actuation tuning in practice.

RhoA-ROCK competes with YAP to regulate amoeboid breast cancer cell migration in response to lymphatic-like flow.

Lymphatic drainage generates force that induces prostate cancer cell motility via activation of Yes‐associated protein (YAP), but whether this response to fluid force is conserved across cancer types is unclear. Here, we show that shear stress corresponding to fluid flow in the initial lymphatics modifies taxis in breast cancer, whereas some cell lines use rapid amoeboid migration behavior in response to fluid flow, a separate subset decrease movement. Positive responders displayed transcriptional profiles characteristic of an amoeboid cell state, which is typical of cells advancing at the edges of neoplastic tumors. Regulation of the HIPPO tumor suppressor pathway and YAP activity also differed between breast subsets and prostate cancer. Although subcellular localization of YAP to the nucleus positively correlated with overall velocity of locomotion, YAP gain‐ and loss‐of‐function demonstrates that YAP inhibits breast cancer motility but is outcompeted by other pro‐taxis mediators in the context of flow. Specifically, we show that RhoA dictates response to flow. GTPase activity of RhoA, but not Rac1 or Cdc42 Rho family GTPases, is elevated in cells that positively respond to flow and is unchanged in cells that decelerate under flow. Disruption of RhoA or the RhoA effector, Rho‐associated kinase (ROCK), blocked shear stress–induced motility. Collectively, these findings identify biomechanical force as a regulator amoeboid cell migration and demonstrate stratification of breast cancer subsets by flow‐sensing mechanotransduction pathways.

Neural correlates of multidimensional motor outputs in an excitatory parafascicular-zona incerta circuit

The parafascicular nucleus (Pf) in medial thalamus is interconnected with prefrontal cortex and basal ganglia. Though much research has determined its importance in cognitive regulation of behaviour, its projections to regions in subthalamus remain less known. Such connections include those to zona incerta (ZI), located immediately dorsal to subthalamic nuclei (STN) regulating motor output, and whose role in a motor context is only beginning to be investigated. We thus examined circuits from parafascicular (Pf) thalamus to ZI, and its activity during locomotion and spontaneous behaviours in mice. We found that a distinct group of CaMKIIα-positive excitatory parafascicular neurons, separated from VGLUT2-positive excitatory neurons, project widely into ZI, more than adjacent STN. Our results from fibre photometry and decoding with general linear model (GLM) indicate that PF-ZI pathways do not specifically correlate with amount of locomotion or movement velocity, but instead show more specified activity during relative directional changes of movements observed in turning, sniffing behaviours. These results hint at the PF-ZI pathway having a distinct role in directing action specificity and have implications for subcortical bases in dimensional control of behaviours.

Design improvement by a simulative investigation of the locomotion of a snake‐like soft robot

AbstractThis work aims to improve the design of a snake‐like soft robot in terms of its velocity of locomotion by a geometric model. Therefore, we determine the locomotion of the snake‐like soft robot as the result of a given excitation curvature and a given friction anisotropy between the robot and the ground.Varying the design parameters of the robot in the model allows to identify important parameters to increase the velocity of locomotion of the snake‐like soft robot. Whereas its body design is sufficient, the transverse friction of its artificial skin is the main parameter to be improved. The transverse friction can be adjusted by turning the scales of the artificial skin. The velocity of locomotion of the robot increases significantly by this simple trick.

Fast-Moving Self-Propelled Droplets of a Nanocatalyzed Belousov-Zhabotinsky Reaction.

Self-sustained locomotion by virtue of an internalized chemical reaction is a characteristic feature of living systems and has inspired researchers to develop such self-moving biomimetic systems. Here, we harness a self-oscillating Belousov-Zhabotinsky (BZ) reaction, a well-known chemical oscillator, with enhanced kinetics by virtue of our graphene-based catalytic mats, to elucidate the spontaneous locomotion of BZ reaction droplets. Specifically, our nanocatalysts comprise ruthenium nanoparticle decorations on graphene oxide, reduced graphene oxide, and graphene nanosheets, thereby creating 0D-2D heterostructures. We demonstrate that when these nanocatalyzed droplets of the BZ reaction are placed in an oil-surfactant medium, they exhibit a macroscopic translatory motion at the velocities of few millimeters per second. This motion is brought about by the combination of enhanced kinetics of the BZ reaction and the Marangoni effect. Our investigations reveal that the velocity of locomotion increases with the electrical conductivity of our nanocomposites. Moreover, we also show that the positive feedback generated by the reaction-diffusion phenomena results in an asymmetric distribution of surface tension that, in turn, facilitates the self-propelled motion of the BZ droplets. Finally, we explore a system of multiple nanocatalyzed BZ droplets and reveal a variety of motions caused by their mutual interactions. Our findings suggest that through the use of 0D-2D hybrid nanomaterials, it is possible to design fast-moving self-propelled synthetic objects for a variety of biomimetic applications.

Kinetic and Kinematic Analysis of Locomotion Speed of Higher Secondary Boys

The purpose was to analyze selected components of locomotion speed. Thirty school boys of age ranging from 17 to 19 year were selected as subject. Selected anthropometric and mechanical parameters were body weight, body height, leg length, maximum locomotion speed, leg power, stride length, stride frequency, body inclination, angle of leg placement in braking phase, push-off angle, horizontal projection of CG in braking phase, horizontal projection of CG in propulsion phase, horizontal velocity of CG in braking phase, horizontal velocity of CG in propulsion phase, velocity of swing leg in braking phase, velocity of swing leg in propulsion phase, angular velocity of thigh in propulsion phase, contact phase, flight phase, braking phase, and propulsion phase. The maximum locomotion speed was determined by a field test. Running action was filmed by a digital video camera with 120 fps for the distance between 40 to 50 m of the 100 m race. The anthropometric parameters were measured using standard procedure. The selected mechanical parameters were analyzed by motion analysis software. Results showed that weight, height, leg length, stride length, stride frequency had higher positive correlation with maximum locomotion velocity, whereas, contact phase, flight phase and propulsion phase had higher negative correlation with maximum locomotion velocity.

Behavioral Parameters of Planarians (Girardia tigrina) as Fast Screening, Integrative and Cumulative Biomarkers of Environmental Contamination: Preliminary Results

The present study aims to use behavioral responses of the freshwater planarian Girardia tigrina to assess the impact of anthropogenic activities on the aquatic ecosystem of the watershed Araguaia-Tocantins (Tocantins, Brazil). Behavioral responses are integrative and cumulative tools that reflect changes in energy allocation in organisms. Thus, feeding rate and locomotion velocity (pLMV) were determined to assess the effects induced by the laboratory exposure of adult planarians to water samples collected in the region of Tocantins-Araguaia, identifying the sampling points affected by contaminants. Furthermore, physicochemical and microbiological parameters, as well as the presence of inorganic compounds (dissolved aluminum, total barium, total chloride, dissolved iron, total fluoride, total manganese, nitrates, nitric nitrogen, total sulfate, total zinc) and surfactants, were determined on each specific sampling point. The behavioral biomarkers (feeding rate and pLMV) of the freshwater planarians were significantly decreased when organisms were exposed to water samples from four municipalities (Formoso do Araguaia, Lagoa da Confusão, Gurupi and Porto Nacional), sites of the Tocantins-Araguaia hydrographic region—TAHR. Both behavioral biomarkers decreased up to ~37–39% compared to organisms in ASTM medium only. Our results showed that these behavioral biomarkers can be used for fast screening monitoring of environmental samples of freshwater ecosystems, since a decrease in feeding rate and locomotor activity was observed in sites impacted by anthropogenic activities. However, the absence of effects observed in some sampling points does not represent the absence of contamination, since several other classes of contaminants were not determined. In these negative results, the absence of deleterious effects on behavioral biomarkers might only be indicative that the potential presence of contaminants on such sites does not significantly affect the performance of planarians. This fast screening approach seems to be useful to determine contaminated sites in freshwater ecosystems for biomonitoring purposes. This knowledge will help to develop biomonitoring programs and to decide appropriate sampling sites and analysis.

Male pheromones modulate synaptic transmission at the C. elegans neuromuscular junction in a sexually dimorphic manner.

The development of functional synapses in the nervous system is important for animal physiology and behaviors, and its disturbance has been linked with many neurodevelopmental disorders. The synaptic transmission efficacy can be modulated by the environment to accommodate external changes, which is crucial for animal reproduction and survival. However, the underlying plasticity of synaptic transmission remains poorly understood. Here we show that in Caenorhabditis elegans, the male environment increases the hermaphrodite cholinergic transmission at the neuromuscular junction (NMJ), which alters hermaphrodites' locomotion velocity and mating efficiency. We identify that the male-specific pheromones mediate this synaptic transmission modulation effect in a developmental stage-dependent manner. Dissection of the sensory circuits reveals that the AWB chemosensory neurons sense those male pheromones and further transduce the information to NMJ using cGMP signaling. Exposure of hermaphrodites to the male pheromones specifically increases the accumulation of presynaptic CaV2 calcium channels and clustering of postsynaptic acetylcholine receptors at cholinergic synapses of NMJ, which potentiates cholinergic synaptic transmission. Thus, our study demonstrates a circuit mechanism for synaptic modulation and behavioral flexibility by sexual dimorphic pheromones.

Leg amputation modifies coordinated activation of the middle leg muscles in the cricket Gryllus bimaculatus

Insects alter their walking pattern in order to respond to demands of an ever-changing environment, such as varying ground surface textures. They also exhibit resilient and flexible ability to retain the capacity to walk even after substantial changes in their body properties, e.g. leg amputation. While the motor control paradigm governing the inter-leg coordination in such adaptive walking has been extensively described in past studies, the mechanism remains unknown. Here, we examined this question by using the cricket (Gryllus bimaculatus), which shows a tetrapod/tripod gait on a flat surfaces, like many other insects. We performed leg amputation experiments to investigate modifications of leg movements and coordination of muscle activities. We simultaneously recorded (1) the leg movements, locomotion velocity, and body rotation and (2) the leg movements and leg muscles activities before and after leg amputation. Crickets displayed adaptive coordination of leg movement patterns in response to amputations. The activation timings of levator muscles in both middle legs tended to synchronize in phase when both legs were amputated at the coxatrochanteral joint. This supports the hypothesis that an intrinsic contralateral connection within the mesothoracic ganglion exists, and that mechanosensory feedback from the legs override this connection, resulting in the anti-phase movement of a normal gait.

Angular variables of climbing geckos in two lateral undulation patterns

Geckos demonstrate flexible and agile locomotion on diverse terrains and surfaces. The lateral undulation pattern referring to the trunk-limbs coordination gives animals advantages in terms of motion speed, dynamical stability, and highly efficient movement. Quantitative analysis of the angular variables of the trunk and limbs was proposed to compare the kinematics of Gekko gecko on the vertical plane in the standing wave and traveling wave of lateral undulation patterns. Thirteen angular variables were measured to illustrate the kinematic characteristics of trunk flexion, girdles rotation, scapula rotation, trunk deflection, femoral/humeral protraction–retraction, abduction–adduction, and rotation around their axes, and knee/elbow flexion-extension. One-way analysis of variance (ANOVA) tested for mean differences between patterns for maximum value, minimum value, and range value of each angular variable. The geckos adapted to the changes in locomotion velocity by dynamically adjusting the joints angular variables. Twenty of the thirty-nine angular values showed a significant pattern effect that presented the variation of angular values or the timing of the peak of the angle curve in two different lateral undulation patterns. The climbing stability of a gecko is tightly associated with the coordination between the body and the limbs.