Exceptional running and turning performance in a mite

Rubin, Samuel J.; Young, Maria Ho-Yan; Wright, J. C.; Whitaker, Dwight; Ahn, Anna

doi:10.1242/jeb.128652

Cited by 29 publications

(25 citation statements)

References 51 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, small-size arthropods outperform larger animals in terms of their relative moving speeds. For example, a small mite, Paratarsotomus macropalpis, is now the world's fastest known running animal, with a relative speed at several hundred body lengths per second (39). An opposite trend exists for soft robots, as shown in the elliptical and blue color shaded area, which For animals including both mammals (purple) and arthropods (orange), relative speeds show a strong negative scaling law with respect to the body mass, showing that relative running speeds increase as body masses decrease.…”

Section: The Comparison Of Relative Moving Speedmentioning

confidence: 99%

“…In particular, arthropods show how rapid, cyclic locomotion at high frequencies at this scale is possible without compromising robustness and survivability in harsh conditions (36,37). Flying mosquitos can oscillate or vibrate their wings at more than 800 Hz (38), and 1-mm mites attain relative ground speeds exceeding 200 body lengths per second (BL/s) (39,40). In this work, we introduce fast and robust insect-scale soft robots based on a curved piezoelectric PVDF unimorph structure to achieve several key advancements: (i) Under an alternating current (AC) driving power near the resonant frequency (850 Hz) of the structure, a prototype 10-mm-long robot (0.024 g) attained a relative speed of 20 BL/s-the fastest among published reports of insect-scale soft ground robots; (ii) after stepping on the robot with an adult human's full body weight (59.5 kg, about 1 million times heavier than the robot), the robot could still move afterward, demonstrating exceptional robustness; (iii) the robot could move smoothly carrying a load weighing 0.406 g, which is six times heavier than that of the robot; (iv) further enhancement of agility was demonstrated by designing the moving mechanism to emulate features of galloping-like gaits using a two-leg prototype robot.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Insect-scale fast moving and ultrarobust soft robot

et al. 2019

View full text Add to dashboard Cite

Mobility and robustness are two important features for practical applications of robots. Soft robots made of polymeric materials have the potential to achieve both attributes simultaneously. Inspired by nature, this research presents soft robots based on a curved unimorph piezoelectric structure whose relative speed of 20 body lengths per second is the fastest measured among published artificial insect-scale robots. The soft robot uses several principles of animal locomotion, can carry loads, climb slopes, and has the sturdiness of cockroaches. After withstanding the weight of an adult footstep, which is about 1 million times heavier than that of the robot, the system survived and continued to move afterward. The relatively fast locomotion and robustness are attributed to the curved unimorph piezoelectric structure with large amplitude vibration, which advances beyond other methods. The design principle, driving mechanism, and operating characteristics can be further optimized and extended for improved performances, as well as used for other flexible devices.

show abstract

Section: The Comparison Of Relative Moving Speedmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Insect-scale fast moving and ultrarobust soft robot

et al. 2019

View full text Add to dashboard Cite

show abstract

“…Sometimes, however, deviations from this model are observed, as with wood ants described by Reinhardt et al Furthermore, some of the fastest legged locomotion relative to body size occurs at scales smaller than those previously studied. For example erythracarid mites (body length of 1 mm) can run at speeds up to 192 body lengths per second (BL s −1 ) (Rubin et al, 2016). So far, few explanations for these speeds exist, in no small part due to the challenges in measuring the underlying mechanics at this scale.…”

Section: Introductionmentioning

confidence: 99%

Gait studies for a quadrupedal microrobot reveal contrasting running templates in two frequency regimes

et al. 2017

View full text Add to dashboard Cite

Performance metrics such as speed, cost of transport, and stability are the driving factors behind gait selection in legged locomotion. To help understand the effect of gait on the performance and dynamics of small-scale ambulation, we explore four quadrupedal gaits over a wide range of stride frequencies on a 1.43 g, biologically-inspired microrobot, the Harvard Ambulatory MicroRobot (HAMR). Despite its small size, HAMR can precisely control leg frequency, phasing, and trajectory, making it an exceptional platform for gait studies at scales relevant to insect locomotion. The natural frequencies of the body dynamics are used to identify frequency regimes where the choice of gait has varying influence on speed and cost of transport (CoT). To further quantify these effects, two new metrics, ineffective stance and stride correlation, are leveraged to capture effects of foot slippage and observed footfall patterns on locomotion performance. At stride frequencies near body resonant modes, gait is found to drastically alter speed and CoT. When running well above these stride frequencies we find a gait-agnostic shift towards energy characteristics that support 'kinematic running', which is defined as a gait with a Froude number greater than one with energy profiles more similar to walking than running. This kinematic running is rapid (8.5 body lengths per second), efficient (CoT = 9.4), different from widely observed SLIP templates of running, and has the potential to simplify design and control for insect-scale runners.

show abstract

“…, which is explicitly indicated by a parameter's functional dependency on M (in parenthesis) in our model description. We apply our model calculations to body mass values that range from M = 10 −8 kg (mites [59]) to M = 10 5 kg (heaviest dinosaurs [60]).…”

Section: Force Equilibrium Maximum Running Speed and Body Sizementioning

confidence: 99%

Rules of nature’sFormula Run: Muscle mechanics during late stance is the key to explaining maximum running speed

Guenther

Rockenfeller

Weihmann

et al. 2020

Preprint

View full text Add to dashboard Cite

The maximum running speed of legged animals is one evident factor for evolutionary selection---for predators and prey. Therefore, it has been studied across the entire size range of animals, from the smallest mites to the largest elephants, and even beyond to extinct dinosaurs. A recent analysis of the relation between animal mass (size) and maximum running speed showed that there seems to be an optimal range of body masses in which the highest terrestrial running speeds occur. However, the conclusion drawn from that analysis---namely, that maximum speed is limited by the fatigue of white muscle fibres in the acceleration of the body mass to some theoretically possible maximum speed---was based on coarse reasoning on metabolic grounds, which neglected important biomechanical factors and basic muscle-metabolic parameters. Here, we propose a generic biomechanical model to investigate the allometry of the maximum speed of legged running. The model incorporates biomechanically important concepts: the ground reaction force being counteracted by air drag, the leg with its gearing of both a muscle into a leg length change and the muscle into the ground reaction force, as well as the maximum muscle contraction velocity, which includes muscle-tendon dynamics, and the muscle inertia---with all of them scaling with body mass. Put together, these concepts' characteristics and their interactions provide a mechanistic explanation for the allometry of maximum legged running speed. This accompanies the offering of an explanation for the empirically found, overall maximum in speed: In animals bigger than a cheetah or pronghorn, the time that any leg-extending muscle needs to settle, starting from being isometric at about midstance, at the concentric contraction speed required for running at highest speeds becomes too long to be attainable within the time period of a leg moving from midstance to lift-off. Based on our biomechanical model we, thus, suggest considering the overall speed maximum to indicate muscle inertia being functionally significant in animal locomotion. Furthermore, the model renders possible insights into biological design principles such as differences in the leg concept between cats and spiders, and the relevance of multi-leg (mammals: four, insects: six, spiders: eight) body designs and emerging gaits. Moreover, we expose a completely new consideration regarding the muscles' metabolic energy consumption, both during acceleration to maximum speed and in steady-state locomotion.

show abstract

Exceptional running and turning performance in a mite

Cited by 29 publications

References 51 publications

Insect-scale fast moving and ultrarobust soft robot

Insect-scale fast moving and ultrarobust soft robot

Gait studies for a quadrupedal microrobot reveal contrasting running templates in two frequency regimes

Rules of nature’sFormula Run: Muscle mechanics during late stance is the key to explaining maximum running speed

Contact Info

Product

Resources

About