Locomotion Mechanism Research Articles

Amoeba-Inspired Magnetic Venom Microrobots.

Nature provides a successful evolutionary direction for single-celled organisms to solve complex problems and complete survival tasks - pseudopodium. Amoeba, a unicellular protozoan, can produce temporary pseudopods in any direction by controlling the directional flow of protoplasm to perform important life activities such as environmental sensing, motility, predation, and excretion. However, creating robotic systems with pseudopodia to emulate environmental adaptability and tasking capabilities of natural amoeba or amoeboid cells remains challenging. Here, this work presents a strategy that uses alternating magnetic fields to reconfigure magnetic droplet into Amoeba-like microrobot, and the mechanisms of pseudopodia generation and locomotion are analyzed. By simply adjusting the field direction, microrobots switch in monopodia, bipodia, and locomotion modes, performing all pseudopod operations such as active contraction, extension, bending, and amoeboid movement. The pseudopodia endow droplet robots with excellent maneuverability to adapt to environmental variations, including spanning 3D terrains and swimming in bulk liquids. Inspired by the "Venom," the phagocytosis and parasitic behaviors have also been investigated. Parasitic droplets inherit all the capabilities of amoeboid robot, expanding their applicable scenarios such as reagent analysis, microchemical reactions, calculi removal, and drug-mediated thrombolysis. This microrobot may provide fundamental understanding of single-celled livings, and potential applications in biotechnology and biomedicine.

Light-sheet microscopy reveals dorsoventral asymmetric membrane dynamics of Amoeba proteus during pressure-driven locomotion.

Amoebae are found all around the world and play an essential role in the carbon cycle in the environment. Therefore, the behavior of amoebae is a crucial factor when considering the global environment. Amoebae change their distribution through amoeboid locomotion, which are classified into several modes. In the pressure-driven mode, intracellular hydrostatic pressure generated by the contraction of cellular cortex actomyosin causes the pseudopod to extend. During amoeboid locomotion, the cellular surface exhibits dynamic deformation. Therefore, to understand the mechanism of amoeboid locomotion, it is important to characterize cellular membrane dynamics. Here, to clarify membrane dynamics during pressure-driven amoeboid locomotion, we developed a polkadot membrane staining method and performed light-sheet microscopy in Amoeba proteus, which exhibits typical pressure-driven amoeboid locomotion. It was observed that the whole cell membrane moved in the direction of movement, and the dorsal cell membrane in the posterior part of the cell moved more slowly than the other membrane. In addition, membrane complexity varied depending on the focused characteristic size of the membrane structure, and in general, the dorsal side was more complex than the ventral side. In summary, the membrane dynamics of Amoeba proteus during pressure-driven locomotion are asymmetric between the dorsal and ventral sides.

Impact of viscoelastic ooze slime on complex wavy gliders near a solid boundary

• Fluid mechanics of bacterial motion is discussed numerically. • Glider is approximated as a 2D complex wavy sheet. • To capture the viscoelastic properties of slime FENE-P fluid model is utilized. • The gliding motion is highly dependent on slime rheology and wave amplitudes. Prokaryote propulsion is bewilderingly diverse. Many bacteria swim through the fluid medium via rotating a long helical flagellum driven by a rotary motor, some possesses helical shaped bodies and use mechanochemical filaments. Rod-shaped Bacteria (present near the solid wall) practice another mechanism of locomotion, generally called gliding motility. It is hypothesized that rod-shaped bacteria propel it selves by producing waves in their body and leave an adhesive slime trail. Based on these observations, we use a mathematical model (of complex undulating sheet) to examine the gliding motility of bacteria on a layer of non-Newtonian slime. FENE-P fluid model is approximated as a layer of non-Newtonian slime. Navier-Stokes equation is simplified using the lubrication assumption which results in a second-order differential equation. The speed of organism, flow rate and energy loss at larger values of the involved parameters are simulated using a blended numerical technique. The streamlines pattern and velocity of the slime are also drawn for the realistic pairs of speed and flow rate and are thoroughly explained.

Dynamic Research on Nonlinear Locomotion of Inchworm-Inspired Soft Crawling Robot.

Inchworm-inspired bionic soft crawling robot (SCR) composed of soft materials possesses preeminent active compliant deformation ability and has obvious advantages over traditional hard robots when moving in a confined space, which is up-and-coming candidate in robotic community. Nevertheless, there are rare investigations on dynamic modeling problems of the SCR allowing for its nonlinear deformation properties and frictional contact that affects its crawling performance. In view of this, within the theoretical framework of absolute nodal coordinate formulation, in consideration of material, geometry, and boundary nonlinearities, combining a multiple-point contact model with the Coulomb friction model, an effective and accurate nonlinear dynamic model for a bioinspired SCR with one single limb is proposed to elucidate its motion law. We implement an in-depth dynamic research and analysis on the SCR in terms of average velocity, stick-slip characteristic, gaits and successfully simulate its successive forward crawling locomotion meanwhile gaining dynamic response. The proposed theoretical dynamic model correctly captures the SCR' complex geometry configurations and nonlinear deformations, discloses its stick-slip dynamic behaviors and crawling locomotion mechanism, whose effectiveness and superiority are validated experimentally, which inspires a deep insight to motion analysis of other types of soft robots, and enlightens new ideas of their diversified architecture designs.

Design of a Magnetic Soft Inchworm Millirobot Based on Pre-Strained Elastomer with Micropillars.

Rather than using longitudinal "muscle" as in biological inchworm, the existing magnetic active elastomer (MAE)-based inchworm robots utilize magnetic torque to pull and push the soft body, which hinders its locomotion mobility. In this paper, a new pre-strained MAE inchworm millirobot with micropillars is proposed. The pre-strained elastomer serves as a pre-load muscle to contract the soft body, and the micropillars act as tiny feet to anchor the body during the locomotion. The proposed magnetic inchworm robot features a simple fabrication process that does not require special magnetization equipment. For the first time, the pre-load muscle is introduced in the design of magnetic inchworm robots, making it more like a real inchworm in terms of locomotion mechanism. The locomotion principle and parametric design for the desired locomotion performance have been investigated. Experimental results show that the fabricated magnetic inchworm robot (size: 10 mm × 5 mm, micropillars length: 200 µm, and mass: 262 g) can locomote on a smooth acrylic surface (roughness of 0.3 µm) at the speed of 0.125 body lengths per second, which is comparable with the existing magnetic inchworm robots. Moreover, the locomotion capabilities of the inchworm robot on wet surfaces and inclined planes have been verified via experimental studies.

The Autonomous Pipeline Navigation of a Cockroach Bio-Robot with Enhanced Walking Stimuli.

Tens of crawling bio-robots with cockroaches as the mobile platform have been developed with various functions. Compared with artificial crawling robots of the same size, they revealed better flexibility, larger payload, and stronger endurance. These features made bio-robots ideal for pipeline inspection scenarios because the advancements in locomotion mechanisms and efficient power systems are still hurdles for current artificial systems. In this study, we controlled the bio-robot to crawl in the confined dark pipeline and achieved autonomous motion control with the help of an onboard sensing system. Specifically, a micro-camera was mounted on the electronic backpack of the cockroach for image collection, and an IMU sensor was used to compute its body orientation. The electronic backpack transmitted images to the host computer for junction recognition and distance estimation. Meanwhile, the insect's habituation to electrical stimulation has long been an uncertain factor in the control of bio-robots. Here, a synergistic stimulation strategy was proposed to markedly reduce the habituation and increase the number of effective turning controls to over 100 times. It is also found that both the increase of payload and the application of stimulations could promote the metabolic rate by monitoring carbon dioxide release. With the integration of synergistic stimulation and autonomous control, we demonstrated the fully autonomous pipeline navigation with our cockroach bio-robot, which realized the cycle number of approximately 10 in a roll. This research provides a novel technology that has the potential for practical applications in the future.

Stair-Climbing Robots: A Review on Mechanism, Sensing, and Performance Evaluation

Indoor service robots have been widely introduced in the fields of cleaning, delivery, education, guidance, and healthcare, etc. in indoor environments. The mobility of an indoor service robot is essential to expanding its applications. However, the mobility of existing indoor service robots is highly limited by surrounding indoor environments. For example, a stair is one of the major obstacles that restrict the reachable areas of indoor service robots. Even though many studies have been performed to develop reliable and fast stair-climbing robots based on legged, tracked, wheel-legged and wheel-linkage mechanisms, a market-dominant stair-climbing robot remains unsolved. This review investigates the efforts of engineers devoted to stair-climbing robots. To this end, the locomotion mechanisms of stair climbing robots are classified and their sensing method are summarized. In this review, we also propose useful criteria for evaluating the stair-climbing ability of an indoor service robot. By virtue of these criteria, the stair-climbing performance of existing robots are qualitatively compared. We hope this review helps develop the reliable and fast stair-climbing robots and the reasonable criteria for their performances.

A Variable Clutch Mechanism for Adjustable Stiffness Actuators Based on Bending and Torsion of Prismatic Beams

Today, a major obstacle to developing locomotion mechanisms that are as safe and energy efficient as living organisms has been overcome with the development of actuators with adjustable stiffness. This work presents an innovative clutch mechanism whose stiffness can be adjusted based on the combined bending and torsion of the prismatic beams. In this way, the stiffness of any rotary actuator can be adjusted with the help of this clutch mechanism. The adjustable clutch mechanism consists of elastic prismatic beams placed in any position in the power transmission unit. The stiffness of the clutch mechanism is controlled by varying the active clutch length of these prismatic elastic beams using an additional actuator. This work is a new version developed to solve the mechanical problems observed in our previous studies using elastic cylindrical beams. Cylindrical beams subjected to dynamic bending have a higher risk of cracking on the cylindrical surface over time. The cross-section of cylindrical beams subjected to bending is very narrow at the point furthest from the center, which bears the greatest load in bending. For this reason, it has been observed that the beams break due to micro-cracks on the surfaces of the cylindrical beams in long-term use. However, the rectangular beam proposed as a solution to this mechanical problem is subject to combined torsion and bending, complicating the analytical solution. In this study, the stiffness variation of an adjustable elastic coupling mechanism depending on the coupling length was obtained with a simplified discrete analytical approach. Torsional and bending stiffness of the prismatic beams were calculated separately, and their sum gave the angular stiffness of the actuator. The analytical results obtained using this simple approach are compared with the experimental and finite element analysis results. The results show that the current design can adjust the stiffness over a wide range and the simple analytical approach gives more accurate results as the clutch length increases.

Untethered unidirectionally crawling gels driven by asymmetry in contact forces

Reversible thermoresponsive hydrogels, which swell and shrink (deswell) in the temperature range of 30° to 60°C, provide an attractive material class for operating untethered soft robots in human physiological and ambient conditions. Crawling has been demonstrated previously with thermoresponsive hydrogels but required patterned or constrained gels or substrates to break symmetry for unidirectional motion. Here, we demonstrate a locomotion mechanism for unidirectionally crawling gels driven by spontaneous asymmetries in contact forces during swelling and deswelling of segmented active thermoresponsive poly(N-isopropylacrylamide) (pNIPAM) and passive polyacrylamide (pAAM) bilayers with suspended linkers. Actuation studies demonstrate the consistent unidirectional movement of these gel crawlers across multiple thermal cycles on flat, unpatterned substrates. We explain the mechanism using finite element simulations and by varying experimental parameters such as the linker stiffness and the number of bilayer segments. We elucidate design criteria and validate experiments using image analysis and finite element models. We anticipate that this mechanism could potentially be applied to other shape-changing locomotors.

Trabecular bone ontogeny tracks neural development and life history among humans and non-human primates

Trabecular bone-the spongy bone inside marrow cavities-adapts to its mechanical environment during growth and development. Trabecular structure can therefore be interpreted as a functional record of locomotor behavior in extinct vertebrates. In this paper, we expand upon traditional links between form and function by situating ontogenetic trajectories of trabecular bone in four primate species into the broader developmental context of neural development, locomotor control, and ultimately life history. Our aim is to show that trabecular bone structure provides insights into ontogenetic variation in locomotor loading conditions as the product of interactions between increases in body mass and neuromuscular maturation.Our results demonstrate that age-related changes in trabecular bone volume fraction (BV/TV) are strongly and linearly associated with ontogenetic changes in locomotor kinetics. Age-related variation in locomotor kinetics and BV/TV is in turn strongly associated with brain and body size growth in all species. These results imply that age-related variation in BV/TV is a strong proxy for both locomotor kinetics and neuromuscular maturation. Finally, we show that distinct changes in the slope of age-related variation in bone volume fraction correspond to the age of the onset of locomotion and the age of locomotor maturity.Our findings compliment previous studies linking bone development to locomotor mechanics by providing a fundamental link to brain development and life history. This implies that trabecular structure of fossil subadults can be a proxy for the rate of neuromuscular maturation and major life history events like locomotor onset and the achievement of adult-like locomotor repertoires.

Sound generated by flow over two traveling wavy foils in a side-by-side arrangement

Numerical simulations are employed to investigate the sound generated by flow over two traveling wavy foils in a side-by-side arrangement by an immersed-boundary-method-based hybrid approach. The effects of Strouhal number (St), phase difference, and lateral spacing (S) between the foils on the flow performance and the sound pressure field are examined. The results imply that the sound produced by a single foil is dominated by the lift dipole, and that the low-amplitude–high-frequency foil can achieve higher thrust and higher sound pressure compared to the high-amplitude–low-frequency foil. For the two side-by-side foils (i.e., an in-phase and anti-phase foil system), the sound pressure fields exhibit distinct features. Specifically, a dipole-like pattern appears during in-phase motion, whereas a monopole-like pattern exists during anti-phase motion. Moreover, the magnitude of the sound pressure increases slightly with increasing S in the in-phase case. However, the sound pressure decreases rapidly when S < 0.7L (foil length) and then remains nearly unchanged when S > 0.7L in the anti-phase case. Furthermore, the anti-phase foil system could improve thrust by increasing power consumption and could generate lower sound pressure compared to the in-phase one due to the distinct differences in wake patterns. The present work is expected to improve the understanding of sound-generation mechanisms of fish-like locomotion and collective motion for relevant biomimetic underwater vehicles.

Bio-Inspired Locomotion Control of Gecko-Mimic Robot: From Biological Observation to Robot Control

By studying animal and human locomotion strategies, mechanisms, patterns, kinematics, and dynamics, bio-inspired locomotion aims to establish a new theory and method of bionic mechanism, motion planning, and stable control, as well as a new concept for developing bio-inspired robots and unmanned systems. Throughout the long history of evolution, animals have shaped robust, complex, and adaptive movements in order to live in difficult environments. Nature provides an endless supply of robot design concepts for many environmental conditions, such as flight [1], swimming [2], and terrestrial movement [3].

Firing behavior of single motor units of the tibialis anterior in human walking as non-invasively revealed by HDsEMG decomposition

Objective. Investigation of the firing behavior of motor units (MUs) provides essential neuromuscular control information because MUs are the smallest organizational component of the neuromuscular system. The MUs activated during human infants’ leg movements and rodent locomotion, mainly controlled by the spinal central pattern generator (CPG), show highly synchronous firing. In addition to spinal CPGs, the cerebral cortex is involved in neuromuscular control during walking in human adults. Based on the difference in the neural control mechanisms of locomotion between rodent, human infants and adults, MU firing behavior during adult walking probably has some different features from the other populations. However, so far, the firing activity of MUs in human adult walking has been largely unknown due to technical issues. Approach. Recent technical advances allow noninvasive investigation of MU firing by high-density surface electromyogram (HDsEMG) decomposition. We investigated the MU firing behavior of the tibialis anterior (TA) muscle during walking at a slow speed by HDsEMG decomposition. Main results. We found recruitment threshold modulation of MU between walking and steady isometric contractions. Doublet firings, and gait phase-specific firings were also observed during walking. We also found high MU synchronization during walking over a wide range of frequencies, probably including cortical and spinal CPG-related components. The amount of MU synchronization was modulated between the gait phases and motor tasks. These results suggest that the central nervous system flexibly controls MU firing to generate appropriate force of TA during human walking. Significance. This study revealed the MU behavior during walking at a slow speed and demonstrated the feasibility of noninvasive investigation of MUs during dynamic locomotor tasks, which will open new frontiers for the study of neuromuscular systems in the fields of neuroscience and biomedical engineering.

Automatic rainwater collecting duct

Today conserving water has become an important issue to solve. Despite taking numerous measures, a viable solution has yet to be discovered. Everyone should be aware of the importance of adopting a water conservation plan. Many rainwater harvesting devices were common in many regions around the world in previous years. However, there is still no reliable way for collecting high-quality rainwater. Physically controlled gadgets are difficult to manipulate according to the user’s needs. So, this project was designed as automatic rainwater collecting duct. The collecting duct contains solid waste like leave and sediments which block the pathway of the water and reduce the quality of rainwater so make the automation in that duct. First of all, the duct is in the downward position by using rain sensor will detect the rain and as the output locomotive mechanism works which rotate a duct in 180-degree upside and purely collect the rainwater after the rain stops the duct rotates another 180 degrees and it back to the initial position of downward, in this way the duct is out of the solid waste stagnant and the collected rainwater is in good quality. The collected water can be stored in a copper tank that is contaminated purely. It can be used for drinking after the first stage of the purification of rainwater.

Evolving and generalising morphologies for locomoting micro-scale robotic agents

Designing locomotive mechanisms for micro-scale robotic systems could enable new approaches to tackling problems such as transporting cargos, or self-assembling into pre-programmed architectures. Morphological factors often play a crucial role in determining the behaviour of micro-systems, yet understanding how to design these aspects optimally is a challenge. This paper explores how the morphology of a multi-cellular micro-robotic agent can be optimised for reliable locomotion using artificial evolution in a stochastic environment. We begin by establishing the theoretical mechanisms that would allow for collective locomotion to emerge from contractile actuations in multiple connected cells. These principles are used to develop a Cellular Potts model, in order to explore the locomotive performance of morphologies in simulation. Evolved morphologies yield significantly better performance in terms of the reliability of the travel direction and the distance covered, compared to random morphologies. Finally, we demonstrate that patterns in evolved morphologies are robust to small imperfections and generalise well to larger morphologies.

Design of a Locomotion Mechanism for a Metamorphic Exploration Robot

Este artículo propone el diseño de un sistema mecánico capaz de ejecutar la morfosis entre un robot caminante tipo hexápodo y un robot esférico, basado en un modelo de 4 barras, permitiendo la exploración en diferentes terrenos y manufactura basada en tecnología de impresión 3D. El diseño de los elementos que integran este prototipo se desarrolló bajo la perspectiva técnica de la metodología Quality Funtion Design (QFD), obteniendo como resultado experimental un sistema Manivela-Balancín acoplado a cada extremidad, el cual permitió la locomoción típica de un robot artrópodo y al mismo tiempo, extender la capacidad de movilidad al generar una mórfosis con el propósito de realizar una locomoción esférica. Esta locomoción se desarrolló con el objetivo de aprovechar la ventaja dinámica en una superficie donde la cubierta del mecanismo permitiera un desplazamiento sin restricciones, específicamente, en un terreno regular plano, bioinspirada en el desplazamiento “flic-flac” de la araña del desierto (Cebrennus Villosus). El análisis cinemático para este modelo fue representado con el método analítico. La geometría y dimensiones de los elementos fueron desarrollados para su fabricación con tecnología de impresión 3D, con base en las propiedades mecánicas del material Poliácido-láctico (PLA), sin comprometer las capacidades de carga y torque de los servomotores del robot Bioloid®, el cual fue empleado como base del diseño. Para comprobar la capacidad del mecanismo se realizó un análisis general de elemento finito, con lo que es posible verificar que el material satisface las propiedades mecánicas necesarias para el uso operacional del mismo.

A biomechanics dataset of healthy human walking at various speeds, step lengths and step widths

The biomechanics of human walking are well documented for standard conditions such as for self-selected step length and preferred speed. However, humans can and do walk with a variety of other step lengths and speeds during daily living. The variation of biomechanics across gait conditions may be important for describing and determining the mechanics of locomotion. To address this, we present an open biomechanics dataset of steady walking at a broad range of conditions, including 33 experimentally-controlled combinations of speed (0.7–2.0 m·s−1), step length (0.5–1.1 m), and step width (0–0.4 m). The dataset contains ground reaction forces and motions from healthy young adults (N = 10), collected using split-belt instrumented treadmill and motion capture systems respectively. Most trials also include pre-computed inverse dynamics, including 3D joint positions, angles, torques and powers, as well as intersegmental forces. Apart from raw data, we also provide five strides of good quality data without artifacts for each trial, and sample software for visualization and analysis.

A Polyimide Film-Based Simple Force Plate for Measuring the Body Mass of Tiny Insects

Insects exhibit excellent maneuvers such as running and flying despite their small bodies; therefore, their locomotion mechanism is expected to provide a design guideline for micromachines. Numerical simulations have been performed to elucidate this mechanism, whereby it is important to develop a model that is physically identical to the target insect's parts to reproduce kinematic dynamics. In particular, in flight, the shape and mass of wings, which flap at high frequencies, are significant parameters. However, small insects such as fruit flies have small, thin, and light wings; thus, their mass cannot be easily measured. In this study, we proposed a high-resolution and simple force plate to measure the mass of each part of a tiny insect. The device consists of a circular plate supported by flat spiral springs made of polyimide film, and a laser displacement meter that detects the displacement of the center of the plate. The simple plate fabrication process requires only a couple of minutes. A fabricated force plate with a sub-N/m spring constant achieved a resolution of less than 2 µg. As a demonstration, the wing mass of the fruit flies was measured. The experimental results suggest that the wings accounted for approximately 0.4% of the body mass.

Nanorobotics in Blood Vessels

Nowadays the use of nanorobots for medical diagnostics is huge. Nanorobots are used to treat these diagnostics and it will be widely used in future. Here, we design a control method which controls the motion of Nanorobots that are sent into human’s blood vessels and it is used as medical therapies. This study investigates the control mechanism for locomotion of nanorobots in blood vessel repair applications. Each nanorobot operating as artificial platelets has only essential characteristics for self-assembling into a mass at the injured blood vessel to reduce blood loss.Electromagnetism can be used to guide the nanorobots to move to a particular point or part of the body. Coils are also used here.

Interactive fiber-elastomer composites for locomotion mechanism

There is a considerable need for research to fully exploit the application potential of adaptive fiber-reinforced plastics based on functional materials, in particular with regard to industry-specific solutions. Hence, this paper presents the development of a locomotion mechanism based on fiber-elastomer composites with shape memory alloys. In order to attain this goal, shape memory alloys were textile-technically integrated into the reinforcing fabric in the weft direction using flat knitting technology. The functionalized reinforcing fabrics was infused by the vacuum assisted resin infusion with an elastomeric silicone matrix system. Later, an extensive electro-thermal-mechanical characterization of the fiber-elastomer composites by varying electrical power caused by the varying voltage amplitude was completed. The fiber-elastomer composites were then shaped in a cross-country ski as an example of locomotion mechanism. Finally, the forward movement of the cross-country skiers was realized by activating the shape memory alloy in the left and right leg.