Maximum Forward Velocity Research Articles

Enhancing Swimming Performance of Magnetic Helical Microswimmers by Surface Microstructure.

Artificial bacterial flagella (ABF), also known as a magnetic helical microswimmer, has demonstrated enormous potential in various future biomedical applications (e.g., targeted drug delivery and minimally invasive surgery). Nevertheless, when used for in vivo/in vitro treatment applications, it is essential to achieve the high motion efficiency of the microswimmers for rapid therapy. In this paper, inspired by microorganisms, the surface microstructure was introduced into ABFs to investigate its effect on the swimming behavior. It was confirmed that compared with smooth counterparts, the ABF with surface microstructure reveals a smaller forward velocity below the step-out frequency (i.e., the frequency corresponding to the maximum velocity) but a larger maximum forward velocity and higher step-out frequency. A hydrodynamic model of microstructured ABF is employed to reveal the underlying movement mechanism, demonstrating that the interfacial slippage and the interaction between the fluid and the microstructure are essential to the swimming behavior. Furthermore, the effect of surface wettability and solid fraction of microstructure on the swimming performance of ABFs was investigated experimentally and analytically, which further reveals the influence of surface microstructure on the movement mechanism. The results present an effective approach for designing fast microrobots for in vivo/in vitro biomedical applications.

Influence of Maximal Strength on Bench Press and Trunk Rotation in Adapted Shot-put: A Pilot Investigation

PURPOSE: Shot-put is a complex ballistic movement that involves segments’ translational and rotational motions. Its goal is to release the shot at maximum forward velocity (strength) at an angle of approximately 40º (rotation). Considering the adapted shot-put, those two components could be more limited in action. Therefore, the present study aimed to examine the correlations among the one-repetition maximum (1RM) test in the bench press (BP1RM) and trunk rotation (TR1RM) and the throwing distance of the adapted shotput and body composition (Fat mass and Fat-free mass [FFM]), and the throwing distance of the adapted shot-put (TD) and 1RM results.METHODS: Eighteen non-professional athletes were evaluated, and their anthropometric data were obtained (bio-impedance measurements). Afterward, the participants performed the BP1RM and TR1RM exercises. Finally, they performed the adapted shot-put in similar conditions as the official competitions, where three trials of ASP were performed, and the best of these trials were assessed.RESULTS: The results showed a significant relationship between the throwing distance and 1RM results for both exercises (BP1RM (<i>p</i>=.040) and TR1RM (<i>p</i>=.002)) and with the amount of FFM (<i>p</i>=.045). Concerning FFM relationships, the results showed a positive relationship with both 1RM exercises (BP1RM (<i>p</i>=.034) and TR1RM (<i>p</i>=.003)). The Fat Mass results demonstrated an inverse correlation only with BP1RM (<i>p</i>=.035).CONCLUSIONS: The results suggest that physical preparation, including BP1RM and TR1RM exercises, are fundamental to improving adapted shot-put performance. This showed preliminary indicators of which variables may influence the adapted shot-put that might help coaches and athletes to improve their performance. Nevertheless, those results should be carefully considered since the movement evaluated was very complex, especially when performed by participants unfamiliar with them, and because the same analysis included both sexes.

A Dielectric Elastomer Actuator-Driven Vibro-Impact Crawling Robot.

Over the last decade, many bio-inspired crawling robots have been proposed by adopting the principle of two-anchor crawling or anisotropic friction-based vibrational crawling. However, these robots are complicated in structure and vulnerable to contamination, which seriously limits their practical application. Therefore, a novel vibro-impact crawling robot driven by a dielectric elastomer actuator (DEA) is proposed in this paper, which attempts to address the limitations of the existing crawling robots. The novelty of the proposed vibro-impact robot lies in the elimination of anchoring mechanisms or tilted bristles in conventional crawling robots, hence reducing the complexity of manufacturing and improving adaptability. A comprehensive experimental approach was adopted to characterize the performance of the robot. First, the dynamic response of the DEA-impact constraint system was characterized in experiments. Second, the performance of the robot was extensively studied and the fundamental mechanisms of the vibro-impact crawling locomotion were analyzed. In addition, effects of several key parameters on the robot’s velocity were investigated. It is demonstrated that our robot can realize bidirectional motion (both forward and backward) by simple tuning of the key control parameters. The robot demonstrates a maximum forward velocity of 21.4 mm/s (equivalent to 0.71 body-length/s), a backward velocity of 16.9 mm/s, and a load carrying capacity of 9.5 g (equivalent to its own weight). The outcomes of this paper can offer guidelines for high-performance crawling robot designs, and have potential applications in industrial pipeline inspections, capsule endoscopes, and disaster rescues.

Accuracy and precision of simpler and lower-cost technologies to measure the initial lean angle, step length and step velocity for forward lean releases

Current technologies to measure the maximum forward lean angle, step length and velocity in a clinical setting are neither simple nor cheap. Therefore, the purpose of this study was to determine the accuracy and precision of four live and one post-processing measurement methods compared to the 3D motion analysis gold standard. Twelve healthy younger adults recovered balance, after being released from six randomly ordered forward initial lean angles, using four different live measurement methods: LabVIEW, load cell, inclinometer and protractor. The initial lean angle, step length and velocity were also calculated in post-processing using 2D video analysis and 3D motion analysis. The LabVIEW method was the most accurate and precise, followed by the protractor, inclinometer and load cell methods. The load cell method was the most complex, followed by the LabVIEW, inclinometer and protractor methods. The LabVIEW method was the most expensive, followed by the load cell, inclinometer and protractor methods. Video analysis was sufficiently accurate and precise, equal in complexity and much less expensive than the gold standard. Simpler and lower-cost technologies to measure the initial lean angle, step length and velocity are sufficiently accurate and precise (live: protractor, post-processing: video analysis) to potentially use in a clinical setting.

Quantitative normal values of helical flow, flow jets and wall shear stress of healthy volunteers in the ascending aorta

Objectives4D flow MRI enables quantitative assessment of helical flow. We sought to generate normal values and elucidate changes of helical flow (duration, volume, length, velocities and rotational direction) and flow jet (displacement, flow angle) as well as wall shear stress (WSS).MethodsWe assessed the temporal helical existence (THEX), maximum helical volume (HVmax), accumulated helical volume (HVacc), accumulated helical volume length (HVLacc), maximum forward velocity (maxVfor), maximum circumferential velocity (maxVcirc), rotational direction (RD) and maximum wall shear stress (WSS) as reported elsewhere using the software tool Bloodline in 86 healthy volunteers (46 females, mean age 41 ± 13 years).ResultsWSS decreased by 42.1% and maxVfor by 55.7% across age. There was no link between age and gender regarding the other parameters.ConclusionThis study provides age-dependent normal values regarding WSS and maxVfor and age- and gender-independent normal values regarding THEX, HVmax, HVacc, HVLacc, RD and maxVcirc.Key Points• 4D flow provides numerous new parameters; therefore, normal values are mandatory.• Wall shear stress decreases over age.• Maximum helical forward velocity decreases over age.

Biomimetic omnidirectional multi-tail underwater robot

Biomimetics adopted as a basis for underwater robotic design to enhance locomotion efficiency, maneuverability, and adaptability has shown an extraordinary vitality and enormous growth potential in the field of underwater robotics. However, most designs are focused on mimicry of a specific aquatic organism or its specific function. Biomimetic approaches to underwater robot design that incorporate combination and coordination of multiple individuals could provide a powerful vehicle to build robotic systems that could go far beyond simply mimicking a specific aquatic organism, which remains largely unexplored. With an increasing requirement of underwater robots in context of professional explorations, measurements, and inspections, the demand for underwater robots with high stability and maneuverability has become more urgent. To this end, this study aims at presenting a novel biomimetic design of an omnidirectional underwater robot with multiple tails. This designed underwater robot with multiple tails is capable of combining different advantageous locomotion modes from fish, frog, octopus, fish swarm, and dolphin formation. Swimming locomotion modes including forward motion, steering, sinking, rising and their combinations can be realized flexibly. The robot can easily switch between arbitrary locomotion modes to achieve fast changes of swimming directions in 3D space. Full demonstrations of swimming locomotion modes and their flexible switch are presented to show the robot’s excellent performance on stability, mobility, and maneuverability. The maximum forward velocity and steering angular velocity of the designed robot in this study can correspondingly reach 1.160 m/s (1.93BL) and 115.7 ∘/s. The resulting prototype is experimentally verified in a laboratory water tank with waves. The robot could be the first of its kind achieving higher stability, mobility, and maneuverability of great potential in working in complex dynamic water environments, and thus would present an alternative and new insight into underwater robotic design and control, focusing on complex water environments.

Locomotion of Bioinspired Underwater Snake Robots Using Metaheuristic Algorithm

Snake Robots (SR) have been successfully deployed and proved to attain bio-inspired solutions owing to its capability to move in harsh environments, a characteristic not found in other kinds of robots (like wheeled or legged robots). Underwater Snake Robots (USR) establish a bioinspired solution in the domain of underwater robotics. It is a key challenge to increase the motion efficiency in underwater robots, with respect to forwarding speed, by enhancing the locomotion method. At the same time, energy efficiency is also considered as a crucial issue for long-term automation of the systems. In this aspect, the current research paper concentrates on the design of effectual Locomotion of Bioinspired Underwater Snake Robots using Metaheuristic Algorithm (LBIUSR-MA). The proposed LBIUSR-MA technique derives a bi-objective optimization problem to maximize the Forward Velocity (FV) and minimize the Average Power Consumption (APC). LBIUSR-MA technique involves the design of Manta Ray Foraging Optimization (MRFO) technique and derives two objective functions to resolve the optimization issue. In addition to these, effective weighted sum technique is also used for the integration of two objective functions. Moreover, the objective functions are required to be assessed for varying gait variables so as to inspect the performance of locomotion. A detailed set of simulation analyses was conducted and the experimental results demonstrate that the developed LBIUSR-MA method achieved a low Average Power Consumption (APC) value of 80. under δ value of 50. The proposed model accomplished the minimum PAC and maximum FV of USR in an effective manner.

Design of a miniature modular inchworm robot with an anisotropic friction skin

SUMMARYThis paper presents the design, analysis, and experimental validation of a miniature modular inchworm robot (MMIR). Inchworm robots are capable of maneuvering in confined spaces due to their small size, a desirable characteristic for surveillance, exploration and search and rescue operations. This paper presents two generations of the MMIR (Version 1—V1 and Version 2—V2) that utilize anisotropic friction skin and an undulatory rectilinear gait to produce locomotion. This paper highlights design improvements and a multi-body dynamics approach to model and simulate the system. The MMIR V2 incorporates a slider-crank four-bar mechanism and a relative body revolute joint to produce high-frequency relative translation and rotation to increase forward velocity and enable turning capabilities. Friction analysis and locomotion experiments were conducted to assess the systems performance on various surfaces, validate the dynamic model and simulation results, and measure the maximum forward velocity. The MMIR V1 and V2 were able to achieve maximum forward velocities of 12.7 mm/s and 137.9 mm/s, respectively. These results are compared to reported results of similar robots published in the literature.

Note: Lever-type bidirectional stick-slip piezoelectric actuator with flexible hinge.

This paper presents a lever-type stick-slip piezoelectric actuator based on the lever amplification principle. The proposed actuator can achieve large strokes, high velocity, and bidirectional actuation with a single piezoelectric stack. The finite element simulation of the lever-type flexible hinge is performed, and the designed prototype is tested. When the voltage is 100 Vp-p, the maximum forward velocity is 7.69 mm/s under the symmetry of 20%. The maximum reverse velocity is 7.12 mm/s under the symmetry of 80%. The maximum forward and reverse displacement deviation within 10 cycles is 0.88 μm, and the maximum load can reach 105 g.

Planar time-optimal paths for asymmetric vehicles in constant flows

This paper introduces a new kinematic model to describe the planar motion of an autonomous underwater vehicle moving in constant current flows. The vehicle is modeled as a rigid body moving at maximum attainable forward velocity with symmetric bounds on the control input for the steering rate. The model approximates the effect a flow will induce on the steering rate of the vehicle due to the asymmetric geometry of the vehicle. By imposing restrictions on the magnitude of the flow, the model is then used to characterize and construct the minimum-time paths that guide the vehicle from a given initial to a final configuration in the plane. Algorithms for the time-optimal path synthesis problem are also introduced, along with several simulations to validate the proposed method. Lastly, insights into how one would approach the energy-optimal problem are given, highlighting the fundamental differences in formulation and methods used to solve for the optimal paths.

Monolithic Piezoelectric Insect With Resonance Walking

This paper describes the design, manufacture, and performance of an untethered hexapod robot titled MinRAR V2. This robot utilizes a monolithic piezoelectric element machined to allow for individual activation of bending actuators. The legs were designed so that the first two resonance modes overlap and therefore produce a walking motion at resonance. The monolithic construction significantly improves the matching of resonance modes between legs when compared with previous designs. Miniature control and high-voltage driving electronics were designed to drive 24 separate piezoelectric elements powered from a single 3.7 V lithium polymer battery. The robot was driven both tethered and untethered, and was able to achieve a maximum forward velocity of 98 mm/s when driven at 190 Hz and 6 mm/s at 5 Hz untethered. The robot is capable of a wide range of movements including banking, on the spot turning, and reverse motion.

Miniature Resonant Ambulatory Robot

This article describes the design, manufacture, and performance of a prototype miniature resonant ambulatory robot that uses piezoelectric actuators to achieve locomotion. Each leg is comprised of two piezoelectric bimorph benders, joined at the tip by a flexure and end effector. Combinations of amplitude and phase can be used to produce a wide range of motions including swinging and lifting. A lumped mass model previously developed is described as a design tool to tune the resonance modes of the end effector. The completed robot was driven with frequencies up to 500 Hz resulting in a maximum forward velocity of approximately 520 mm/s at 350 Hz. A frequency analysis was also performed to determine the effects of ground contact on the performance of the robot. This analysis showed a significant reduction in the resonance gain and frequency.

Application of Large Scale Particle Image Velocimetry (LSPIV) to Identify Flow Pattern in a Channel

This study has three main goals, first, to map the flow structure in a channel using a unique technique named Large Scale Particle Image Velocimetry (LSPIV). Second, to test the sensitivity of LSPIV results to LSPIV parameters (e.g., Interrogation Area, and Searching Area). Third, to test the capability of LSPIV method in predicting the magnitude and direction of flow velocity in a complex flow structure. An LSPIV system was set to observe 14 (fourteen) runs of laboratory re-circulating trapezoidal open channel with a sudden expansion-constriction shape in its middle reach. LSPIV technique was successfully mapping the core flow and the swirling motions near the wall in the expansion-constriction reach. In the core flow region, longitudinal velocity, U, estimate was sensitive to the interrogation area and searching area parameters, while lateral velocity, V, estimate was insensitive to those parameters. The opposite condition occurred in the wall region. The maximum forward flow velocity U was 0.56 m/s occurred in the core flow region. This value was closed to channel bulk velocity Ubulk=0.4 m/s measured using flow meters. The largest backward velocity was 0.068 m/s, obtained in left wall region where the swirling motion occurred.

감조하천에서 조위 및 유량조건에 따른 역류 분석

The Han River is the only waterway in Korea where estuary is not blocked by dykes so that tidal water is flowing in and out through the tidal reach. The extreme tidal range in the Yellow Sea causes an intense flood current, stretching over horizontal extents of tens of kilometers into the rivers. To elucidate the flow reversal by discharge conditions and transient tidal level in the Han river, numerical simulations were conducted under 7 boundary conditions for two days with 10 minute time step. As the flow conditions changed from low discharge and high tidal difference to high discharge and low tidal difference, the flow reversals became weaker and the velocity of forward flow direction became higher due to the increased flow momentums and decreased tidal differences. In the case of normal flow, the maximum reverse velocity was 0.4 m/s, which was equivalent to the maximum forward velocity. In addition, the pattern of the development and decay of forward and reverse flow was presented.

A MEMS linear accelerator for levitated micro-objects

In this work, the design, micro-fabrication, and characterization steps of a contactless linear accelerator is presented. The proposed design in principle can levitate conductive micro-objects and accelerate or move them over a predefined trajectory. The levitation is realized using electromagnetic induction generated by a changing AC field whereas the propulsion is achieved through electrostatic forces from a controlled DC source. This is the first time in literature that such a hybrid design is used to accomplish this idea. It has been experimentally shown that the proposed design can levitate 1mm×1mm sized and 7μm thick micro-objects to a maximum height of 75μm and propel them forward continuously at a maximum average forward velocity of 3.6mm/s.

A Numerical Study of Jet Propulsion of an Oblate Jellyfish Using a Momentum Exchange-Based Immersed Boundary-Lattice Boltzmann Method

AbstractIn present paper, the locomotion of an oblate jellyfish is numerically investigated by using a momentum exchange-based immersed boundary-Lattice Boltzmann method based on a dynamic model describing the oblate jellyfish. The present investigation is agreed fairly well with the previous experimental works. The Reynolds number and the mass density of the jellyfish are found to have significant effects on the locomotion of the oblate jellyfish. Increasing Reynolds number, the motion frequency of the jellyfish becomes slow due to the reduced work done for the pulsations, and decreases and increases before and after the mass density ratio of the jellyfish to the carried fluid is 0.1. The total work increases rapidly at small mass density ratios and slowly increases to a constant value at large mass density ratio. Moreover, as mass density ratio increases, the maximum forward velocity significantly reduces in the contraction stage, while the minimum forward velocity increases in the relaxation stage.

Decentralized Coordination of Constrained Fixed-wing Unmanned Aerial Vehicles: Circular Orbits

UAVs are promising platforms for various missions such as remote sensing of agricultural products, forest fire surveillance, search-and-rescue and border monitoring. A relevant common challenge in the above missions is that of convergence to an objective circular orbit. To address this challenge for fixed-wing UAVs, intrinsic constraints such as nonholonomic nature of the vehicle, minimum and maximum forward velocity, maximum angular velocity and limited detection range must be considered. In this paper, a decentralized coordination strategy is developed so that a number of fixed-wing UAVs converge to an objective circle, respecting the mentioned constraints. Also, a priority-based collision avoidance scheme is proposed to avoid inter-UAV collision. Convergence of the system is proved by analysis of the finite state machine associated with the coordination algorithm. Simulation results are presented to verify the feasibility of the proposed approach.

Trypanosome Motion Represents an Adaptation to the Crowded Environment of the Vertebrate Bloodstream

Blood is a remarkable habitat: it is highly viscous, contains a dense packaging of cells and perpetually flows at velocities varying over three orders of magnitude. Only few pathogens endure the harsh physical conditions within the vertebrate bloodstream and prosper despite being constantly attacked by host antibodies. African trypanosomes are strictly extracellular blood parasites, which evade the immune response through a system of antigenic variation and incessant motility. How the flagellates actually swim in blood remains to be elucidated. Here, we show that the mode and dynamics of trypanosome locomotion are a trait of life within a crowded environment. Using high-speed fluorescence microscopy and ordered micro-pillar arrays we show that the parasites mode of motility is adapted to the density of cells in blood. Trypanosomes are pulled forward by the planar beat of the single flagellum. Hydrodynamic flow across the asymmetrically shaped cell body translates into its rotational movement. Importantly, the presence of particles with the shape, size and spacing of blood cells is required and sufficient for trypanosomes to reach maximum forward velocity. If the density of obstacles, however, is further increased to resemble collagen networks or tissue spaces, the parasites reverse their flagellar beat and consequently swim backwards, in this way avoiding getting trapped. In the absence of obstacles, this flagellar beat reversal occurs randomly resulting in irregular waveforms and apparent cell tumbling. Thus, the swimming behavior of trypanosomes is a surprising example of micro-adaptation to life at low Reynolds numbers. For a precise physical interpretation, we compare our high-resolution microscopic data to results from a simulation technique that combines the method of multi-particle collision dynamics with a triangulated surface model. The simulation produces a rotating cell body and a helical swimming path, providing a functioning simulation method for a microorganism with a complex swimming strategy.

Ball height during backswing and its influence on tenpin bowling performance

In tenpin bowling, it is common for coaches to suggest that bowlers display a higher backswing in order to generate higher peak ball velocity during swing (PBvel). This stems from the assumption that the swing is akin to a pendulum, whereby the speed of the ball is dependent on the potential energy gained from its starting height. The primary objective of this study was to ascertain whether maximum ball height (BHNorm) during backswing is related to PBvelor bowling score average (BSave). The study also compared BHNormbetween elite and backup bowlers. Participants were assigned into two groups based on their BSave over three tournaments, with those averaging above 200 pin falls placed in the elite group. There were 18 elite (M=10, F=8; BSave 213±7) and 12 backup bowlers (M=7, F=5; BSave 181±9). Ball height and velocity data were derived from Kwon3D system utilising four 100 Hz cameras. BHNormwas the vertical distance between the maximum ball height during backswing and the lowest point during swing, normalised to subject's height. PBvelwas the maximum linear forward velocity of the ball near release. Participants aimed for a strike at each of the four trials, the mean scores were used. In terms of relationship to bowling performance, BHNormhad no significant (p<0.05) relationship to BSave (r=0.00) and PBvel(r=0.01). Comparisons of BHNormbetween the elite and backup group also yielded no significant differences. Contrary to the popular notion that raising the ball higher will lead to higher release velocity, the height a ball is raised during backswing does not seem to correspond with higher ball speeds, nor does it relate to better bowling scores. The latter is supported by the fact that there was no significant difference in BHNormbetween the different level bowlers. It can be suggested that the ball height during backswing is more of a choice of individual preference rather than the need to generate more ball speed.

Acid phosphatase production by Rhizopus delemar: A role played in the Ni(II) bioaccumulation process

The microbial growth and activity of acid phosphatase enzyme during the growth of Rhizopus delemar in the presence or absence of Ni(II) ions were investigated. An increase in initial Ni(II) ion concentration inhibited both growth rate of R. delemar and acid phosphatase activity. The maximum-intrinsic specific growth rate (μm) and Monod constant (Ks) of microorganism in Ni(II)-free medium were found as 0.0649h−1 and 1.8928g/L, respectively. The inhibition of Ni(II) ions on growth rate of R. delemar was found to be a competitive inhibition and the inhibition constant was found to be 67.11mg Ni(II)/L. The intrinsic Michaelis–Menten constant (Km) and maximum forward velocity of the reaction (vm) were determined as 3.17mM and 833.3μmol/Lmin, respectively, in Ni(II)-free medium. In the presence of Ni(II) ions, the activity of acid phosphatase was inhibited. Addition of Ni(II) ions decreased the maximum reaction velocity, vm, showed noncompetitive-type inhibition kinetics and the inhibition constant was determined as 50mg Ni(II)/L. Maximum Ni(II) uptake was obtained by the growing cells of R. delemar, while the uptake capacity of resting cells was lowest. This study proved that acid phosphatase enzyme participated in the Ni(II) bioaccumulation mechanism of growing R. delemar.