scholarly journals Drosophila uses a tripod gait across all walking speeds, and the geometry of the tripod is important for speed control

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Chanwoo Chun ◽  
Tirthabir Biswas ◽  
Vikas Bhandawat
Keyword(s):  
Simple Model ◽  
Spatial Resolution ◽  
Inverted Pendulum ◽  
Walking Speed ◽  
High Spatial Resolution ◽  
Center Of Mass ◽  
Mass Movement ◽  
Speed Control ◽  
Tripod Gait ◽  
Walking Speeds

Changes in walking speed are characterized by changes in both the animal’s gait and the mechanics of its interaction with the ground. Here we study these changes in walking Drosophila. We measured the fly’s center of mass movement with high spatial resolution and the position of its footprints. Flies predominantly employ a modified tripod gait that only changes marginally with speed. The mechanics of a tripod gait can be approximated with a simple model – angular and radial spring-loaded inverted pendulum (ARSLIP) – which is characterized by two springs of an effective leg that become stiffer as the speed increases. Surprisingly, the change in the stiffness of the spring is mediated by the change in tripod shape rather than a change in stiffness of individual legs. The effect of tripod shape on mechanics can also explain the large variation in kinematics among insects, and ARSLIP can model these variations.

The Control of Walking in Orthoptera

1973 ◽  
Vol 58 (1) ◽  
pp. 45-58
Author(s):  
M. D. BURNS
Keyword(s):  
Walking Speed ◽  
Schistocerca Gregaria ◽  
Relative Independence ◽  
Straight Line ◽  
Tripod Gait ◽  
High Level ◽  
Walking Speeds ◽  
Leg Movements

1. The patterns of leg movements during normal straight-line walking of the locust Schistocerca gregaria and the grasshopper Romalea microptera were recorded and analysed. 2. The ratio of protraction to retraction increased with walking speed except in the prothoracic legs. At any one speed both protraction and retraction durations were variable but the variation was greatest for protraction. 3. The locust employed an alternating tripod gait at all walking speeds recorded (2-8 steps/sec.) It displayed a high level of variability in its leg movements which appeared to be held in check by stabilising mechanisms operating on the first and last leg pairs. 4. The movements of individual legs of the grasshopper were very similar to those of the locust but the gait used was not alternating tripod. 5. Comparisons were made with other insects and it was suggested that the specialization of the metathoracic legs in the locust gave rise to most of the variability in leg movements and that the relative independence of the prothoracic legs reflects an exploratory role in walking.

Interlimb Coordination During Slow Walking in the Cockroach: I. Effects of Substrate Alterations

1979 ◽  
Vol 78 (1) ◽  
pp. 233-243 ◽  
Author(s):  
CARL P. SPIRITO ◽  
DANIEL L. MUSHRUSH
Keyword(s):  
Control System ◽  
Walking Speed ◽  
Interlimb Coordination ◽  
Steering Control ◽  
Inclined Plane ◽  
Slow Walking ◽  
Tripod Gait ◽  
Walking Speeds

In this study, interlimb coordination in the cockroach during slow walking (2–7 steps/s) is described for a variety of substrate conditions. During normal free-walking, the animal utilizes an alternating tripod gait (both ipsilateral and contralateral phase close to 0.50). The protraction/retraction ratio varies linearly with walking speed. When tethered on a supported ball, the ipsilateral phase ranges from 0.32 to 0.46 at walking speeds of 2-7 steps/s, and contralateral phase is constant at 0.53. Protraction/retraction ratios are normal in this case. Blind free-walking animals use a gait which is indistinguishable from normal, but the protraction/retraction ratio is constant over speeds of 2-7 steps/s. When walking down an inclined plane (45°), the gait resembles ball-walking, with an average ipsilateral phase of 0.43 and contralateral phase of 0.53. These alterations of gait under different substrate conditions can be related to the animal's responses to loading, gravity, and steering control system.

scholarly journals A Method of Speed Control during Over-Ground Walking: Using a Digital Light-Emitting Diode Light Strip

2013 ◽  
Vol 718-720 ◽  
pp. 1371-1376 ◽  
Author(s):  
Liang Huang ◽  
Jie Zhuang ◽  
Yan Xin Zhang
Keyword(s):  
Walking Speed ◽  
Light Emitting Diode ◽  
Speed Control ◽  
Visual Cue ◽  
Light Emitting ◽  
Custom Made ◽  
Percent Difference ◽  
Average Percent Difference ◽  
Walking Speeds ◽  
Over Ground Walking

The purpose of this report was to introduce the design of a portable, inexpensive and programmable digital light-emitting diode (LED) system to control overground walking speed. The system includes a custom-made 10 meters digital LED strip and a digital microcontroller. By controlling the duration time of the power supply to each LED unit, a visible running lights signal can provide a visual cue for speed control. To evaluate this design, five subjects were asked to walk overground while following the LED visual cue at five different target speeds. The actual walking speeds were determined using Vicon motion capture system. The results of this evaluation showed a good match between the actual and desired speeds. The average percent difference was 2.51%, measured over 250 walking trials by the subjects. 98% of trials had an percent difference smaller than 6.5%, which is the maximum tolerated error within the literature. The inter-trial reliability for the LED speed control system ranged from 0.85 to 0.88 for faster speeds (1.6 m/s, 1.4 m/s), and slightly lower ranging from 0.74 to 0.79 at slower speeds (1.2 m/s, 1.0 m/s, 0.8 m/s).

Heel-Contact Toe-Off Walking Pattern Generator Based on the Linear Inverted Pendulum

2016 ◽  
Vol 13 (01) ◽  
pp. 1650002 ◽  
Author(s):  
Yukitoshi Minami Shiguematsu ◽  
Przemyslaw Kryczka ◽  
Kenji Hashimoto ◽  
Hun-Ok Lim ◽  
Atsuo Takanishi
Keyword(s):  
Simple Model ◽  
Humanoid Robot ◽  
Inverted Pendulum ◽  
Center Of Mass ◽  
Pattern Generator ◽  
Walking Pattern ◽  
Heel Contact ◽  
Zero Moment ◽  
Two Stages ◽  
Multibody Dynamics Model

We propose a novel heel-contact toe-off walking pattern generator for a biped humanoid robot. It is divided in two stages: a simple model stage where a Linear Inverted Pendulum (LIP) based heel-contact toe-off walking model based on the so-called functional rockers of the foot (heel, ankle and forefoot rockers) is used to calculate step positions and timings, and the Center of Mass (CoM) trajectory taking step lengths as inputs, and a multibody dynamics model stage, where the final pattern to implement on the humanoid robot is obtained from the output of the first simple model stage. The final pattern comprises the Zero Moment Point (ZMP) reference, the joint angle references and the end effector references. The generated patterns were implemented on our robotic platform, WABIAN-2R to evaluate the generated walking patterns.

scholarly journals Walking Stability of a Variable Length Inverted Pendulum Controlled with Virtual Constraints

2019 ◽  
Vol 16 (06) ◽  
pp. 1950040
Author(s):  
Qiuyue Luo ◽  
Christine Chevallereau ◽  
Yannick Aoustin
Keyword(s):  
Periodic Motion ◽  
Inverted Pendulum ◽  
Walking Speed ◽  
Center Of Mass ◽  
Pi Controller ◽  
Variable Length ◽  
Bipedal Walking ◽  
Human Walking ◽  
Walking Gait ◽  
Switching Condition

Bipedal walking is a complex phenomenon that is not fully understood. Simplified models make it easier to highlight the important features. Here, the variable length inverted pendulum (VLIP) model is used, which has the particularity of taking into account the vertical oscillations of the center of mass (CoM). When the desired walking gait is defined as virtual constraints, i.e., as functions of a phasing variable and not on time, for the evolution of the swing foot and the vertical oscillation of the CoM, the walk will asymptotically converge to the periodic motion under disturbance with proper choice of the virtual constraints, thus a self-stabilization is obtained. It is shown that the vertical CoM oscillation, positions of the swing foot and the choice of the switching condition play crucial roles in stability. Moreover, a PI controller of the CoM velocity along the sagittal axis is also proposed such that the walking speed of the robot can converge to another periodic motion with a different walking speed. In this way, a natural walking gait is illustrated as well as the possibility of velocity adaptation as observed in human walking.

Nervous Mechanisms Underlying Intersegmental Co-Ordination of Leg Movements During Walking in the Cockroach

1973 ◽  
Vol 58 (3) ◽  
pp. 725-744
Author(s):  
K. G. PEARSON ◽  
J. F. ILES
Keyword(s):  
Sensory Input ◽  
Walking Speed ◽  
Campaniform Sensilla ◽  
Mutual Inhibition ◽  
Leg Muscles ◽  
Slow Walking ◽  
Tripod Gait ◽  
Walking Speeds ◽  
Generating System ◽  
Leg Movements

1. The activity in identical motoneurones innervating leg muscles of the three thoracic segments of the cockroach has been recorded in (a) normal walking animals, (b) walking animals after lesions to the nervous system and/or amputation of the mesothoracic legs, and (c) restrained de-afferented preparations. 2. The phase of levator motoneurone burst activity of the mesothoracic leg in the metathoracic cycle is almost 0·5 for all walking speeds above 2 steps/sec, confirming that a tripod gait is used at all but the slowest speeds. 3. The burst-generating systems in each segment are centrally coupled because in de-afferented preparations there is a tendency for the bursts in the mesothoraci segment to begin near the end of the metathoracic bursts, and vice versa. 4. Sensory input from leg receptors is also important in co-ordinating stepping movements of the different legs since (a) there are some differences in motoneurone activity of de-afferented and walking preparations, and (b) amputation of the mesothoracic legs at the trochanter leads to an immediate change in the co-ordination of the remaining four legs. 5. It is proposed that two mechanisms are important in co-ordinating leg movements in a slow walking cockroach (a) mutual inhibition between levator burst-generating systems in adjacent ipsilateral legs, and (b) an inhibitory reflex pathway from the campaniform sensilla of the trochanter to the burst-generating system of each leg. The second of these two mechanisms may become less important as the walking speed increases.

scholarly journals Vibrotactile Stimulation of Nail of Hallux during Walking: Effect on Center-of-Mass Movement in Healthy Young Adults

2020 ◽  
Vol 10 (13) ◽  
pp. 4562
Author(s):  
Haruki Toda ◽  
Yuki Hashimoto ◽  
Mitsunori Tada
Keyword(s):  
Walking Speed ◽  
Lateral Displacement ◽  
Center Of Mass ◽  
Mass Movement ◽  
Vibrotactile Stimulation ◽  
Lateral Direction ◽  
Large Variability ◽  
Young Males ◽  
Stance Time ◽  
Stimulation Of

Previous studies have reported that vibrotactile stimulation of the nail of the hallux decreases the variability of the center-of-mass (CoM) movement in the lateral direction in subjects performing unsteady walking on the spot. This study investigated the effect of vibrotactile stimulation of the nail of the hallux on the CoM movement during walking. Healthy young males were asked to walk with and without stimulation, and their CoM was measured. The intrasubject mean and coefficient of variation (CV) of their walking speed, stance time, and CoM movement were evaluated. The differences between the variables with and without stimulation were determined, and the baseline-dependent effects of the stimulation on these variables were analyzed. It was observed that stimulation had a negative baseline-dependent effect on the CVs of the walking speed, stance time, and the CoM movement in the lateral direction. In particular, stimulation decreased the CV of the CoM movement in the lateral direction for subjects with a greater variability. Vibrotactile stimulation of the nail of the hallux can reduce the variability of the lateral displacement of the CoM movement in healthy young subjects who otherwise show a large variability of the CoM movement during walking without stimulation.

scholarly journals Spring-loaded inverted pendulum goes through two contraction-extension cycles during the single stance phase of walking

2019 ◽  
Author(s):  
Gabriel Antoniak ◽  
Tirthabir Biswas ◽  
Nelson Cortes ◽  
Siddhartha Sikdar ◽  
Chanwoo Chun ◽  
...  
Keyword(s):  
Stance Phase ◽  
Inverted Pendulum ◽  
Center Of Mass ◽  
Legged Locomotion ◽  
Quantitative Model ◽  
Active Elements ◽  
Mechanical Models ◽  
Reaction Forces ◽  
Spring Loaded Inverted Pendulum ◽  
Walking Speeds

AbstractDespite the overall complexity of legged locomotion, the motion of the center of mass (COM) itself is relatively simple, and can be qualitatively described by simple mechanical models. The spring-loaded inverted pendulum (SLIP) is one such model, and describes both the COM motion and the ground reaction forces (GRFs) during running. Similarly, walking can be modeled by two SLIP-like legs (double SLIP or DSLIP). However, DSLIP has many limitations and is unlikely to serve as a quantitative model for walking. As a first step to obtaining a quantitative model for walking, we explored the ability of SLIP to model the single stance phase of walking across the entire range of walking speeds. We show that SLIP can be employed to quantitatively model the single stance phase except for two exceptions: first, it predicts larger horizontal GRFs than empirically observed. A new model - angular and radial spring-loaded inverted pendulum (ARSLIP) can overcome this deficit. Second, even the single stance phase has active elements, and therefore a quantitative model of locomotion would require active elements. Surprisingly, the leg spring undergoes a contraction-extension-contraction-extension (CECE) during walking; this cycling is partly responsible for the M-shaped GRFs produced during walking. The CECE cycle also lengthens the stance duration allowing the COM to travel passively for a longer time, and decreases the velocity redirection between the beginning and end of a step. A combination of ARSLIP along with active mechanisms during transition from one step to the next is necessary to describe walking.

High spatial resolution AEM observations of yttrium segregation in chromia scales grown on Co-45%Cr

1986 ◽  
Vol 44 ◽  
pp. 518-519
Author(s):  
K. Przybylski ◽  
A. J. Garratt-Reed ◽  
G. J. Yurek
Keyword(s):  
Spatial Resolution ◽  
Outer Surface ◽  
Maximum Concentration ◽  
High Spatial Resolution ◽  
Reactive Elements ◽  
Chromia Scales

The addition of so-called “reactive” elements such as yttrium to alloys is known to enhance the protective nature of Cr2O3 or Al2O3 scales. However, the mechanism by which this enhancement is achieved remains unclear. An A.E.M. study has been performed of scales grown at 1000°C for 25 hr. in pure O2 on Co-45%Cr implanted at 70 keV with 2x1016 atoms/cm2 of yttrium. In the unoxidized alloys it was calculated that the maximum concentration of Y was 13.9 wt% at a depth of about 17 nm. SIMS results showed that in the scale the yttrium remained near the outer surface.

Integration of Core-Edge Spectroscopy Methods for the Study of Polymers

1996 ◽  
Vol 54 ◽  
pp. 154-155
Author(s):  
E. G. Rightor
Keyword(s):  
Excited State ◽  
Polymer Blends ◽  
Gas Phase ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Electronic States ◽  
Core Electron ◽  
Bulk Solids ◽  
Development Application

Core edge spectroscopy methods are versatile tools for investigating a wide variety of materials. They can be used to probe the electronic states of materials in bulk solids, on surfaces, or in the gas phase. This family of methods involves promoting an inner shell (core) electron to an excited state and recording either the primary excitation or secondary decay of the excited state. The techniques are complimentary and have different strengths and limitations for studying challenging aspects of materials. The need to identify components in polymers or polymer blends at high spatial resolution has driven development, application, and integration of results from several of these methods.

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