Fast and slow processes underlie the selection of both step frequency and walking speed

Humans spontaneously select a step frequency that minimizes the energy expenditure of walking. This selection might be embedded within the neural circuits that generate gait so that the optimum is pre-programmed for a given walking speed. Or perhaps step frequency is directly optimized, based on sensed feedback of energy expenditure. Direct optimization is expected to be slow due to the compounded effect of delays and iteration, whereas a pre-programmed mechanism presumably allows for faster step frequency selection, albeit dependent on prior experience. To test for both pre-programmed selection and direct optimization, we applied perturbations to treadmill walking to elicit transient changes in step frequency. We found that human step frequency adjustments ( n = 7) occurred with two components, the first dominating the response (66 ± 10% of total amplitude change; mean ± SD) and occurring quite quickly (1.44 ± 1.14 s to complete 95% of total change). The other component was of smaller amplitude (35 ± 10% of total change) and took tens of seconds (27.56 ± 16.18 s for 95% completion). The fast process appeared to be too fast for direct optimization and more indicative of a pre-programmed response. It also persisted even with unusual closed-loop perturbations that conflicted with prior experience and rendered the response energetically suboptimal. The slow process was more consistent with the timing expected for direct optimization. Our interpretation of these results is that humans may rely heavily on pre-programmed gaits to rapidly select their preferred step frequency and then gradually fine-tune that selection with direct optimization.

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Framework for Developing Bio-Inspired Morphologies for Walking Robots

Applied Sciences ◽

10.3390/app10196986 ◽

2020 ◽

Vol 10 (19) ◽

pp. 6986

Author(s):

Peter Billeschou ◽

Nienke N. Bijma ◽

Leon B. Larsen ◽

Stanislav N. Gorb ◽

Jørgen C. Larsen ◽

...

Keyword(s):

Walking Speed ◽

Dung Beetle ◽

Object Manipulation ◽

Step Length ◽

Legged Robots ◽

Walking Robots ◽

Beetle Species ◽

Step Frequency ◽

Development Framework ◽

Interdisciplinary Collaborations

Morphology is a defining trait of any walking entity, animal or robot, and is crucial in obtaining movement versatility, dexterity and durability. Collaborations between biologist and engineers create opportunities for implementing bio-inspired morphologies in walking robots. However, there is little guidance for such interdisciplinary collaborations and what tools to use. We propose a development framework for transferring animal morphologies to robots and substantiate it with a replication of the ability of the dung beetle species Scarabaeus galenus to use the same morphology for both locomotion and object manipulation. As such, we demonstrate the advantages of a bio-inspired dung beetle-like robot, ALPHA, and how its morphology outperforms a conventional hexapod by increasing the (1) step length by 50.0%, (2) forward and upward reach by 95.5%, and by lowering the (3) overall motor acceleration by 7.9%, and (4) step frequency by 21.1% at the same walking speed. Thereby, the bio-inspired robot has longer and fewer steps that lower fatigue-inducing impulses, a greater variety of step patterns, and can potentially better utilise its workspace to overcome obstacles. Hence, we demonstrate how the framework can be used to develop legged robots with bio-inspired morphologies that embody greater movement versatility, dexterity and durability.

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Insect–computer hybrid legged robot with user-adjustable speed, step length and walking gait

Journal of The Royal Society Interface ◽

10.1098/rsif.2016.0060 ◽

2016 ◽

Vol 13 (116) ◽

pp. 20160060 ◽

Cited By ~ 20

Author(s):

Feng Cao ◽

Chao Zhang ◽

Hao Yu Choo ◽

Hirotaka Sato

Keyword(s):

Walking Speed ◽

Step Length ◽

Legged Robot ◽

Step Frequency ◽

Locomotion Control ◽

Insect Locomotion ◽

Implanted Electrodes ◽

Walking Gait ◽

Leg Muscles ◽

Adjustable Speed

We have constructed an insect–computer hybrid legged robot using a living beetle ( Mecynorrhina torquata ; Coleoptera). The protraction/retraction and levation/depression motions in both forelegs of the beetle were elicited by electrically stimulating eight corresponding leg muscles via eight pairs of implanted electrodes. To perform a defined walking gait (e.g. gallop), different muscles were individually stimulated in a predefined sequence using a microcontroller. Different walking gaits were performed by reordering the applied stimulation signals (i.e. applying different sequences). By varying the duration of the stimulation sequences, we successfully controlled the step frequency and hence the beetle's walking speed. To the best of our knowledge, this paper presents the first demonstration of living insect locomotion control with a user-adjustable walking gait, step length and walking speed.

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The Effect of Stiff Foot Plate Length on Walking Gait Mechanics

Journal of Biomechanical Engineering ◽

10.1115/1.4046882 ◽

2020 ◽

Vol 142 (9) ◽

Author(s):

Dave Schmitthenner ◽

Carolyn Sweeny ◽

Jing Du ◽

Anne E. Martin

Keyword(s):

Walking Speed ◽

Knee Kinematics ◽

Foot And Ankle ◽

Step Frequency ◽

Walking Gait ◽

Plate Length ◽

Ankle Kinematics ◽

Gait Parameters ◽

Gait Mechanics ◽

Reaction Forces

Abstract Exoskeletons are increasingly being used to treat gait pathologies. Many of these exoskeletons use a foot plate to actuate the foot, altering the effective stiffness of the foot. Stiffness of the biological foot and ankle plays an important role in the energy modulating function of the leg, so it is important to examine how a foot plate in and of itself impacts gait. Therefore, this study quantified how foot plates themselves alter the walking gait of 16 healthy young adults. The effect of the foot plate length was also examined through the use of two foot plates, one that ended at the metatarsals and one that extended past the toes, about 20% longer. Gait parameters examined included walking speed, step frequency, joint angles for the hip, knee, ankle, forefoot, and toe, ground reaction forces (GRF), and foot–ankle power. The most significant changes were caused by the full plate, which caused an average 13% decrease in the ankle range of motion (ROM) and a 23% decrease in forward GRF at push off. The shorter plate also decreased ankle ROM to a lesser degree. This indicates that the presence of a foot plate impacted foot and ankle kinematics. However, the presence of the tested foot plate had no effect on walking speed or hip or knee kinematics. This indicates that subjects were mostly able to compensate both kinematically and energetically via their foot and ankle for the increased foot stiffness due to the tested foot plate.

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Optimizing the Scale of a Wavelet-Based Method for the Detection of Gait Events from a Waist-Mounted Accelerometer under Different Walking Speeds

Sensors ◽

10.3390/s19081869 ◽

2019 ◽

Vol 19 (8) ◽

pp. 1869 ◽

Cited By ~ 8

Author(s):

Carlotta Caramia ◽

Cristiano De Marchis ◽

Maurizio Schmid

Keyword(s):

Inertial Sensor ◽

Initial Contact ◽

Vertical Acceleration ◽

Strongly Correlated ◽

Step Frequency ◽

Wide Range ◽

All Speeds ◽

Events Detection ◽

Walking Speeds ◽

Selection Of

The accurate and reliable extraction of specific gait events from a single inertial sensor at waist level has been shown to be challenging. Among several techniques, a wavelet-based method for initial contact (IC) and final contact (FC) estimation was shown to be the most accurate in healthy subjects. In this study, we evaluated the sensitivity of events detection to the wavelet scale of the algorithm, when walking at different speeds, in order to optimize its selection. A single inertial sensor recorded the lumbar vertical acceleration of 20 subjects walking at three different self-selected speeds (slow, normal, and fast) in a motion analysis lab. The scale of the wavelet method was varied. ICs were generally accurately detected in a wide range of wavelet scales under all the walking speeds. FCs detection proved highly sensitive to scale choice. Different gait speeds required the selection of a different scale for accurate detection and timing, with the optimal scale being strongly correlated with subjects’ step frequency. The best speed-dependent scales of the algorithm led to highly accurate timing in the detection of IC (RMSE < 22 ms) and FC (RMSE < 25 ms) across all speeds. Our results pave the way for the optimal adaptive selection of scales in future applications using this algorithm.

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Study of Symmetric Solutions of an Underactuated Bipedal Robot

Volume 4A: Dynamics, Vibration, and Control ◽

10.1115/imece2018-87723 ◽

2018 ◽

Author(s):

Prachi Shah ◽

Vivek Sangwan

Keyword(s):

Energy Efficiency ◽

Walking Speed ◽

Solution Space ◽

Bipedal Walking ◽

Walking Robot ◽

Bipedal Robot ◽

The Past ◽

The Family ◽

Two Parameter ◽

Selection Of

Underactuated bipedal walking has been intensively studied for the past few decades and several methods have been proposed to design trajectories; however, quickly generating trajectories with varying speeds remains a challenge. One solution is to have a library of trajectories precomputed from which a new one can be picked or constructed quickly based on specific requirements. For this to become feasible one needs to develop a good understanding of the solution space. This is non-trivial for a non-linear hybrid system such as a walking robot. The goal of this study is to explore a two parameter solution space of simple underactuated biped, under a specific virtual constraint, used in literature, to enforce a symmetric gait. The family of feasible walking solutions identified is further evaluated for performance and energy efficiency. This analysis can potentially facilitate quick selection of walking trajectories for meeting specific walking speed and efficiency requirements.

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Effects of Walking Speed and Step Frequency on Estimation of Physical Activity Using Accelerometers

Journal of PHYSIOLOGICAL ANTHROPOLOGY ◽

10.2114/jpa2.30.119 ◽

2011 ◽

Vol 30 (3) ◽

pp. 119-127 ◽

Cited By ~ 32

Author(s):

Jonghoon Park ◽

Kazuko Ishikawa-Takata ◽

Shigeho Tanaka ◽

Yuko Mekata ◽

Izumi Tabata

Keyword(s):

Physical Activity ◽

Walking Speed ◽

Step Frequency

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Shifts in Gait Signatures Mark the End of Lifespan in Mice, With Sex Differences in Timing

Frontiers in Aging Neuroscience ◽

10.3389/fnagi.2021.716993 ◽

2021 ◽

Vol 13 ◽

Author(s):

Lauren Broom ◽

Jessica Stephen ◽

Varun Nayar ◽

Veronique G. VanderHorst

Keyword(s):

Sex Differences ◽

Stride Length ◽

Walking Speed ◽

Functional Decline ◽

Slow Motion ◽

Mature Adult ◽

Adult Age ◽

Age Related ◽

Speed Dependence ◽

Selection Of

Reduced walking speed is a hallmark of functional decline in aging across species. An age-related change in walking style may represent an additional key marker signifying deterioration of the nervous system. Due to the speed dependence of gait metrics combined with slowing of gait during aging, it has been challenging to determine whether changes in gait metrics represent a change in style. In this longitudinal study we employed gait signatures to separate changes in walking style and speed in mice. We compared gait signatures at mature adult age with middle aged, old and geriatric time points and included female and male sub-cohorts to examine sex differences in nature or timing signature shifts. To determine whether gait signature shifts occurred independently from a decline in other mobility domains we measured balance and locomotor activity. We found that walking speed declined early, whereas gait signatures shifted very late during the aging process. Shifts represented longer swing time and stride length than expected for speed, as in slow motion, and were preceded by a decline in other mobility domains. The pattern of shifts was similar between female and male cohorts, but with sex differences in timing. We conclude that changes in walking style, speed and other mobility domains represent separate age-related phenomena. These findings call for careful, sex specific selection of type and timing of outcome measures in mechanistic or interventional studies. The pattern of age-related gait signature shifts is distinct from patterns seen in neurodegenerative conditions and may be a translatable marker for the end of the lifespan.

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Natural Frequency Method: estimating the preferred walking speed of Tyrannosaurus rex based on tail natural frequency

Royal Society Open Science ◽

10.1098/rsos.201441 ◽

2021 ◽

Vol 8 (4) ◽

Author(s):

Pasha A. van Bijlert ◽

A. J. ‘Knoek’ van Soest ◽

Anne S. Schulp

Keyword(s):

Energy Storage ◽

Natural Frequency ◽

Elastic Energy ◽

Walking Speed ◽

Natural Frequencies ◽

Body Parts ◽

Step Frequency ◽

Frequency Method ◽

Cost Of Transport ◽

Moment Arms

Locomotor energetics are an important determinant of an animal's ecological niche. It is commonly assumed that animals minimize locomotor energy expenditure by selecting gait kinematics tuned to the natural frequencies of relevant body parts. We demonstrate that this allows estimation of the preferred step frequency and walking speed of Tyrannosaurus rex , using an approach we introduce as the Natural Frequency Method. Although the tail of bipedal dinosaurs was actively involved in walking, it was suspended passively by the caudal interspinous ligaments. These allowed for elastic energy storage, thereby reducing the metabolic cost of transport. In order for elastic energy storage to be high, step and natural frequencies would have to be matched. Using a 3D morphological reconstruction and a spring-suspended biomechanical model, we determined the tail natural frequency of T. rex (0.66 s −1 , range 0.41–0.84), and the corresponding walking speed (1.28 m s −1 , range 0.80–1.64), which we argue to be a good indicator of preferred walking speed (PWS). The walking speeds found here are lower than earlier estimations for large theropods, but agree quite closely with PWS of a diverse group of extant animals. The results are most sensitive to uncertainties regarding ligament moment arms, vertebral kinematics and ligament composition. However, our model formulation and method for estimation of walking speed are unaffected by assumptions regarding muscularity, and therefore offer an independent line of evidence within the field of dinosaur locomotion.

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Cognitive gadgets and cognitive priors

Behavioral and Brain Sciences ◽

10.1017/s0140525x19000992 ◽

2019 ◽

Vol 42 ◽

Author(s):

Gian Domenico Iannetti ◽

Giorgio Vallortigara

Keyword(s):

Cognitive Neuroscience ◽

Selection Of

Abstract Some of the foundations of Heyes’ radical reasoning seem to be based on a fractional selection of available evidence. Using an ethological perspective, we argue against Heyes’ rapid dismissal of innate cognitive instincts. Heyes’ use of fMRI studies of literacy to claim that culture assembles pieces of mental technology seems an example of incorrect reverse inferences and overlap theories pervasive in cognitive neuroscience.

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