scholarly journals Side-Impact Collision: Mechanics of Obstacle Negotiation in Sidewinding Snakes

2020 ◽  
Author(s):  
Henry C. Astley ◽  
Jennifer M. Rieser ◽  
Abdul Kaba ◽  
Veronica M. Paez ◽  
Ian Tomkinson ◽  
...  
Keyword(s):  
Natural Habitat ◽  
Body Waves ◽  
Side Impact ◽  
Behavioral Strategies ◽  
Cluttered Environments ◽  
Heterogeneous Habitats ◽  
Static Contact ◽  
Lateral Undulation ◽  
Crotalus Cerastes ◽  
And Control

AbstractSnakes excel at moving through cluttered environments, and heterogeneities can be used as propulsive contacts for snakes performing lateral undulation. However, sidewinding, often associated with sandy deserts, cuts a broad path through the environment that may increase the vulnerability to obstacles. Our prior work demonstrated that sidewinding can be represented as a pair of orthogonal body waves (vertical and horizontal) that can be independently modulated to achieve high maneuverability and incline ascent, suggesting that sidewinders may also use template modulations to negotiate obstacles. To test this hypothesis, we recorded overhead video of four sidewinder rattlesnakes (Crotalus cerastes) crossing a line of vertical pegs placed in the substrate. Snakes used three methods to traverse the obstacles: a Propagate Through behavior in which the lifted moving portion of the snake was deformed around the peg and dragged through as the snake continued sidewinding (115/160 runs), Reversal turns that reorient the snake entirely (35/160), or switching to Concertina locomotion (10/160). The Propagate-Through response was only used if the anterior-most region of static contact would propagate along a path anterior to the peg, or if a new region of static contact could be formed near the head to satisfy this condition; otherwise, snakes could only use Reversal Turns or switch to Concertina locomotion. Reversal Turns allowed the snake to re-orient and either escape without further peg contact or resorting to Propagate Through. We developed an algorithm to reproduce the Propagate Through behavior in a robotic model using a modulation of the two-wave template. This range of behavioral strategies provides sidewinders with a versatile range of options for effectively negotiating obstacles in their natural habitat, as well as provide insights into the design and control of robotic systems dealing with heterogeneous habitats.

scholarly journals Slithering CSF: Cerebrospinal Fluid Dynamics in the Stationary and Moving Viper Boa, Candoia aspera

Biology ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 672
Author(s):  
Bruce A. Young ◽  
Skye Greer ◽  
Michael Cramberg
Keyword(s):  
Cerebrospinal Fluid ◽  
Cardiac Cycle ◽  
Low Frequency ◽  
Mean Amplitude ◽  
The Body ◽  
Body Waves ◽  
Lower Amplitude ◽  
Lateral Undulation ◽  
Recovery From Anesthesia ◽  
The Relationship

In the viper boa (Candoia aspera), the cerebrospinal fluid (CSF) shows two stable overlapping patterns of pulsations: low-frequency (0.08 Hz) pulses with a mean amplitude of 4.1 mmHg that correspond to the ventilatory cycle, and higher-frequency (0.66 Hz) pulses with a mean amplitude of 1.2 mmHg that correspond to the cardiac cycle. Manual oscillations of anesthetized C. aspera induced propagating sinusoidal body waves. These waves resulted in a different pattern of CSF pulsations with frequencies corresponding to the displacement frequency of the body and with amplitudes greater than those of the cardiac or ventilatory cycles. After recovery from anesthesia, the snakes moved independently using lateral undulation and concertina locomotion. The episodes of lateral undulation produced similar influences on the CSF pressure as were observed during the manual oscillations, though the induced CSF pulsations were of lower amplitude during lateral undulation. No impact on the CSF was found while C. aspera was performing concertina locomotion. The relationship between the propagation of the body and the CSF pulsations suggests that the body movements produce an impulse on the spinal CSF.

A Comprehensive Review on Reconfigurable Drones: Classification, Characteristics, Design and Control Technologies

2021 ◽  
pp. 1-27
Author(s):  
Saddam Hocine Derrouaoui ◽  
Yasser Bouzid ◽  
Mohamed Guiatni ◽  
Islam Dib
Keyword(s):  
Fault Tolerant ◽  
Control Strategies ◽  
Cluttered Environments ◽  
Viable Solution ◽  
Promising Solution ◽  
Design Characteristics ◽  
And Performance ◽  
Control Technologies ◽  
And Control ◽  
Near Future

Recently, reconfigurable drones have gained particular attention in the field of automation and flying robots. Unlike the conventional drones, they are characterized by a variable mechanical structure in flight, geometric adaptability, aerial reconfiguration, high number of actuators and control inputs, and variable mathematical model. In addition, they are exploited to flight in more cluttered environments, avoid collisions with obstacles, transport and grab objects, cross narrow and small spaces, decrease different aerial damages, optimize the consumed energy, and improve agility and maneuverability in flight. Moreover, these new drones are considered as a viable solution to provide them with specific and additional functionalities. They are a promising solution in the near future, since they allow increasing considerably the capabilities and performance of classical drones in terms of multi-functionalities, geometric adaptation, design characteristics, consumed energy, control, maneuverability, agility, efficiency, obstacles avoidance, and fault tolerant control. This paper explores very interesting and recent research works, which include the classification, the main characteristics, the various applications, and the existing designs of this particular class of drones. Besides, an in-depth review of the applied control strategies will be presented. The links of the videos displaying the results of these researches will be also shown. A comparative study between the different types of flying vehicles will be established. Finally, several new challenges and future directions for reconfigurable drones will be discussed.

Bio-Inspired Snake Robots

2018 ◽  
pp. 246-275 ◽  
Author(s):  
Mohammadali Javaheri Koopaee ◽  
Cid Gilani ◽  
Callum Scott ◽  
XiaoQi Chen
Keyword(s):  
Future Research ◽  
Snake Robot ◽  
Cluttered Environments ◽  
Flat Surfaces ◽  
Robot Locomotion ◽  
Control Schemes ◽  
Unstructured Environment ◽  
And Control ◽  
World Environment ◽  
Snake Robots

This chapter concerns modelling and control of snake robots. Specifically, the authors' main goal is introducing some of the fundamental design, modelling, and control approaches introduced for efficient snake robot locomotion in cluttered environments. This is a critical topic because, unlike locomotion in flat surfaces, where pre-specified gait equations can be employed, for locomotion in unstructured environment more sophisticated control approaches should be used to achieve intelligent and efficient mobility. To reach this goal, shape-based modelling approaches and a number of available control schemes for operation in unknown environments are presented, which hopefully motivates more scholars to start working on snake robots. Some ideas about future research plans are also proposed, which can be helpful for fabricating a snake robot equipped with the necessary features for operation in a real-world environment.

scholarly journals Reconfigurable Motion Planning and Control in Obstacle Cluttered Environments under Timed Temporal Tasks

2019 ◽  
Author(s):  
Christos K. Verginis ◽  
Constantinos Vrohidis ◽  
Charalampos P. Bechlioulis ◽  
Kostas J. Kyriakopoulos ◽  
Dimos V. Dimarogonas
Keyword(s):  
Motion Planning ◽  
Cluttered Environments ◽  
Planning And Control ◽  
And Control

EFFECT OF VAIRIMORPHA SP.1 ON SURVIVAL OF GEOCORIS PUNCTIPES2 IN THE LABORATORY

1985 ◽  
Vol 20 (3) ◽  
pp. 354-358 ◽  
Author(s):  
O. G. Marti ◽  
J. J. Hamm
Keyword(s):  
Spodoptera Frugiperda ◽  
Natural Habitat ◽  
Fall Armyworm ◽  
Spore Dispersal ◽  
Control Groups ◽  
Geocoris Punctipes ◽  
And Control

Survival of Geocoris punctipes (Say) (Hemiptera: Lygaeidae) after ingestion of fall armyworm, Spodoptera frugiperda (J. E. Smith), tissues infected with Vairimorpha sp. (Microspora: Microsporida) was studied in the laboratory. In six tests involving 532 adult G. punctipes, survival averaged 38.1 days when infected larvae were consumed and 42.9 days when healthy larvae were eaten. These means were significantly different (P < 0.05). There was no germination of Vairimorpha spores or development of the pathogen in G. punctipes. Differences in survival between treated and control groups were attributed to ingestion of a non-nutritive meal equivalent to a brief period of starvation. The insect should be able to compensate in its natural habitat by seeking other prey. We believe the potential of this insect as a vector in spore dispersal outweighs the relatively minor effects of spore ingestion observed in the laboratory.

Muscular mechanisms of snake locomotion: an electromyographic study of the sidewinding and concertina modes of Crotalus cerastes, Nerodia fasciata and Elaphe obsoleta

1988 ◽  
Vol 140 (1) ◽  
pp. 1-33 ◽  
Author(s):  
B. C. Jayne
Keyword(s):  
Muscle Activity ◽  
Body Region ◽  
Longissimus Dorsi ◽  
Lateral Flexion ◽  
Elaphe Obsoleta ◽  
Active Muscle ◽  
Nerodia Fasciata ◽  
Static Contact ◽  
Crotalus Cerastes ◽  
Epaxial Muscles

Synchronized electromyography and cinematography were used to determine the muscle activity of colubroid snakes during sidewinding and concertina locomotion. The primary muscles studied were the three largest, most superficial epaxial muscles: the Mm. semispinalis-spinalis, longissimus dorsi and iliocostalis. Sidewinding locomotion of Nerodia fasciata and Crotalus cerastes was the result of continuous posterior propagation of contractile blocks consisting of several adjacent muscle segments. During sidewinding, the activity of the M. longissimus dorsi and M. iliocostalis was primarily unilateral, beginning when a body region was convex and ending when it was maximally concave on the side of the active muscle. Unilateral activity of the M. semispinalis-spinalis correlated with lateral flexion in addition to bilateral activity that correlated with dorsiflexion of the vertebral column. During concertina locomotion of N. fasciata and Elaphe obsoleta, muscle activity also involved blocks of several simultaneously active adjacent muscle segments, but all major activity was unilateral and was not propagated posteriorly in a simple continuous fashion. Muscle activity during concertina locomotion correlated either with lateral flexion towards the side of the active muscle or with the maintenance of static contact with the sides of a tunnel. The number of simultaneously active adjacent muscle segments and the maximum duration of continuous muscle activity varied significantly between Nerodia and Elaphe and among the different widths of tunnels. Theoretical considerations combined with observed differences suggest that the more elongate body of Elaphe is advantageous for performing concertina locomotion. There was no consistent evidence that nonhomologous muscles with tendinous interconnections functioned as single units during either of these two locomotor modes. Although individual segments of the studied epaxial muscles span several vertebrae, via long, tendinous connections, consistent kinematic correlations with muscle activity were observed only between the contractile portion of a muscle segment and the vertebrae adjacent to that contractile portion.

scholarly journals Editorial for special collection on the estimation and control of MAV navigation in GPS-denied cluttered environments

2018 ◽  
Vol 10 (2) ◽  
pp. 125-126
Author(s):  
Julien Marzat ◽  
Guido de Croon ◽  
Friedrich Fraundorfer ◽  
Pascal Morin ◽  
Antonios Tsourdos
Keyword(s):  
Cluttered Environments ◽  
Special Collection ◽  
Estimation And Control ◽  
And Control

scholarly journals Teacher Frustration and Emotion Regulation in University Language Teaching

2018 ◽  
Vol 41 (4) ◽  
pp. 433-452 ◽  
Author(s):  
Sam Morris ◽  
Jim King
Keyword(s):  
Emotion Regulation ◽  
Language Instruction ◽  
Language Teachers ◽  
Foreign Language Instruction ◽  
Behavioral Strategies ◽  
Stimulated Recall ◽  
Semistructured Interviews ◽  
Student Misbehavior ◽  
And Control ◽  
Student Apathy

Abstract Few jobs come without irritations, and foreign language instruction comes with its own particular set of frustrations which, when accumulated, can lead to stress and eventual burnout for teachers. One mechanism for reducing such frustrations is that of emotion regulation, the cognitive and behavioral strategies individuals employ to manage the emotions they experience or display. To date, no known studies have reported specifically on the in-class frustration experienced by language teachers, or on how teachers regulate their feelings of frustration. Herein, the authors discuss the experiences of seven EFL teachers at a university in Japan obtained through a series of semistructured interviews, classroom observations and corresponding stimulated-recall sessions. The authors discuss four salient thematic frustrations: student apathy, classroom silence, misbehavior in the context of relational strain, and working conditions. The results reveal that participants applied contextually-dependent emotion regulation behaviors, the success of which was often contingent on the participants’ levels of confidence and control over the stressors. Thus, participants showed more success in managing pervasive low-level stressors such as apathy and silence, and more support would be welcome to aid them to manage more debilitating stressors such as student misbehavior. The authors offer suggestions for teachers, trainers and institutions on reducing frustration.

scholarly journals Modulation of orthogonal body waves enables high maneuverability in sidewinding locomotion

2015 ◽  
Vol 112 (19) ◽  
pp. 6200-6205 ◽  
Author(s):  
Henry C. Astley ◽  
Chaohui Gong ◽  
Jin Dai ◽  
Matthew Travers ◽  
Miguel M. Serrano ◽  
...  
Keyword(s):  
Motor Pattern ◽  
Body Waves ◽  
Wave System ◽  
Single Plane ◽  
Snake Robot ◽  
Horizontal Wave ◽  
Terrestrial Environments ◽  
Wave Cycle ◽  
Crotalus Cerastes ◽  
High Degree

Many organisms move using traveling waves of body undulation, and most work has focused on single-plane undulations in fluids. Less attention has been paid to multiplane undulations, which are particularly important in terrestrial environments where vertical undulations can regulate substrate contact. A seemingly complex mode of snake locomotion, sidewinding, can be described by the superposition of two waves: horizontal and vertical body waves with a phase difference of ±90°. We demonstrate that the high maneuverability displayed by sidewinder rattlesnakes (Crotalus cerastes) emerges from the animal’s ability to independently modulate these waves. Sidewinder rattlesnakes used two distinct turning methods, which we term differential turning (26° change in orientation per wave cycle) and reversal turning (89°). Observations of the snakes suggested that during differential turning the animals imposed an amplitude modulation in the horizontal wave whereas in reversal turning they shifted the phase of the vertical wave by 180°. We tested these mechanisms using a multimodule snake robot as a physical model, successfully generating differential and reversal turning with performance comparable to that of the organisms. Further manipulations of the two-wave system revealed a third turning mode, frequency turning, not observed in biological snakes, which produced large (127°) in-place turns. The two-wave system thus functions as a template (a targeted motor pattern) that enables complex behaviors in a high-degree-of-freedom system to emerge from relatively simple modulations to a basic pattern. Our study reveals the utility of templates in understanding the control of biological movement as well as in developing control schemes for limbless robots.

scholarly journals Study on Multi-Agent Evolutionary Game of Emergency Management of Public Health Emergencies Based on Dynamic Rewards and Punishments

2021 ◽  
Vol 18 (16) ◽  
pp. 8278
Author(s):  
Ruguo Fan ◽  
Yibo Wang ◽  
Jinchai Lin
Keyword(s):  
Public Health ◽  
Emergency Management ◽  
Simulation Analysis ◽  
Evolutionary Game ◽  
Behavioral Strategies ◽  
Public Health Emergencies ◽  
Multi Agent ◽  
Punishment Mechanism ◽  
And Control ◽  
Reward And Punishment

In the context of public health emergency management, it is worth studying ways to mobilize the enthusiasm of government, community, and residents. This paper adopts the method of combining evolutionary game and system dynamics to conduct a theoretical modeling and simulation analysis on the interactions of the behavioral strategies of the three participants. In response to opportunistic behavior and inadequate supervision in the static reward and punishment mechanism, we introduced a dynamic reward and punishment mechanism that considers changes in the social environment and the situation of epidemic prevention and control. This paper proves that the dynamic reward and punishment mechanism can effectively suppress the fluctuation problem in the evolutionary game process under static scenarios and achieve better supervision results through scenario analysis and simulation experiments.

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