scholarly journals Position-Posture Control of Multilegged Walking Robot Based on Kinematic Correction

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Liang Zhang ◽  
Yaguang Zhu ◽  
Feifei Zhang ◽  
Shuangjie Zhou
Keyword(s):  
Position Control ◽  
Body Position ◽  
Control Process ◽  
The Body ◽  
Posture Control ◽  
Effective Control ◽  
Adjustment Process ◽  
Multilegged Walking Robot ◽  
Posture Adjustment ◽  
Robot Platform

Posture-position control is the fundamental technology among multilegged robots as it is hard to get an effective control on rough terrain. These robots need to constantly adjust the position-posture of its body to move stalely and flexibly. However, the actual footholds of the robot constantly changing cause serious errors during the position-posture control process because their foot-ends are basically in nonpoint contact with the ground. Therefore, a position-posture control algorithm for multilegged robots based on kinematic correction is proposed in this paper. Position-posture adjustment is divided into two independent motion processes: robot body position adjustment and posture adjustment. First, for the two separate adjustment processes, the positions of the footholds relative to the body are obtained and their positions relative to the body get through motion synthesis. Then, according to the modified inverse kinematics solution, the joint angles of the robot are worked out. Unlike the traditional complex closed-loop position-posture control of the robot, the algorithm proposed in this paper can achieve the purpose of reducing errors in the position-posture adjustment process of the leg-foot robot through a simple and general kinematic modification. Finally, this method is applied in the motion control of a bionic hexapod robot platform with a hemispherical foot-end. A comparison experiment of linear position-posture change on the flat ground shows that this method can reduce the attitude errors, especially the heading error reduced by 55.46%.

Proprioceptive hair cells on the neck of the squid Lolliguncula brevis :a sense organ in cephalopods for the control of head-to-body position

1995 ◽  
Vol 349 (1328) ◽  
pp. 153-178 ◽  
Keyword(s):  
Hair Cells ◽  
Position Control ◽  
Body Position ◽  
Sense Organ ◽  
The Body ◽  
Sensory Cells ◽  
Posterior Group ◽  
Left And Right ◽  
Head Roll ◽  
Lolliguncula Brevis

Decapod cephalopods, such as cuttlefishes and squids, have a distinct neck region that allows movements (roll, pitch and yaw) of the head relative to the body. This paper describes the structure, innervation and central pathways of proprioceptive hair cells on the neck of the squid Lolliguncula brevis that sense such movements and control head-to-body position. These hair cells exist on the dorsal side of the neck underneath the nuchal cartilage, close to the animal’s midline on either side of the nuchal crest. On each side, the hair cells can be divided into an anterior and a posterior group of 25—35 and 70—80 cells, respectively. An individual hair cell carries up to 300 kinocilia of equal length (about 30 pm), arranged in up to seven rows. The hair cells of the left and right anterior group are morphologically polarized in the medial direction, whereas the hair cells of the left and right posterior group are polarized in the anterior direction. The hair cells are primary sensory cells. They are innervated by a branch of the postorbital nerve and project ipsilaterally into the ventral part of the ventral magnocellular lobe. Efferent synaptic contacts are present at the base of the hair cells. In behavioural tests the influence of the neck hair cells on head position control was investigated. During imposed body rolls, a unilateral deafferentation of the cells caused an asymmetric change of the compensatory head roll response and elicited a head roll offset to the operated side. Bilateral deafferentation of the cells elicited a downward head pitch offset. This offset was superimposed on the compensatory head pitch response during imposed body pitch. These morphological and behavioural findings show that the neck hair cells and the associated nuchal cartilage structures of Lolliguncula brevis form a neck receptor organ that, together with statocyst an visua inputs, controls the position of the animal’s head and body.

scholarly journals Dynamic Modeling and Simulation of a Body Weight Support System

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Zhendong Song ◽  
Wei Chen ◽  
Wenbing Wang ◽  
Guoqing Zhang
Keyword(s):  
Body Weight ◽  
Control Process ◽  
Vertical Motion ◽  
The Body ◽  
Body Weight Support ◽  
Gait Rehabilitation ◽  
Series Elastic Actuator ◽  
Weight Support ◽  
Support Force ◽  
Body Weight Support System

This paper proposes a body weight support (BWS) system with a series elastic actuator (SEA) to facilitate walking assistance and motor relearning during gait rehabilitation. This system comprises the following: a mobile platform that ensures movement of the system on the ground, a BWS mechanism with an SEA that is capable of providing the desired unloading force, and a pelvic brace to smooth the pelvis motions. The control of the body weight support is realized by an active weight-offload method, and a dynamic model of the BWS system with offload mass of a human is conducted to simulate the control process and optimize the parameters. Preliminary results demonstrate that the BWS system can provide the desired support force and vertical motion of the pelvis.

Obesity impairs performing and learning a timing perception task regardless of the body position

2021 ◽  
Author(s):  
Fernanda Mottin Refinetti ◽  
Ricardo Drews ◽  
Umberto Cesar Corrêa ◽  
Flavio Henrique Bastos
Keyword(s):  
Body Position ◽  
The Body ◽  
Perception Task ◽  
Timing Perception

Lepeophtheirus salmonis (Krøyer, 1837): second nauplius and copepodid locomotor appendages, surface areas and possible appendage functions

Crustaceana ◽  
2013 ◽  
Vol 86 (13-14) ◽  
pp. 1695-1710 ◽  
Author(s):  
Susan E. Allen ◽  
A. G. Lewis
Keyword(s):  
Body Position ◽  
Ventral Surface ◽  
Total Surface Area ◽  
The Body ◽  
Lepeophtheirus Salmonis ◽  
Sinking Rate ◽  
Surface Areas ◽  
Thoracic Legs ◽  
Two Stages ◽  
Suitable Location

Locomotor appendage-body relationships were used to examine whether swimming or reduction in sinking rate is the more important function in the second nauplius and copepodid stages of Lepeophtheirus salmonis (Krøyer, 1837). Except for the similarity in swimming appendage surface areas without setae, the appendages of the two stages are morphologically distinct. Although the nauplius is smaller than the copepodid it has long slender appendages that, with setae, provide greater total surface area than the paddle-shaped copepodid thoracic legs. Copepodid thoracic legs are more similar to those used for swimming by planktonic copepods although with more limited propulsion capability. Naupliar appendages project from the body while copepodid appendages can be folded against the ventral surface, improving hydrodynamic flow as well as body position after attachment to a host. Both copepodid and naupliar appendages are of sufficient size that they should provide escape velocities of more than 100 mm ⋅ s−1. The nature and display of the naupliar appendages suggest they could be used to reduce sinking rate by as much as 64%, reducing the need to swim to maintain a suitable location in the water. Although copepodid thoracic legs could reduce sinking rate by over 40%, their position on the ventral surface and the nature of other appendages suggests a more important use, for orientation and attachment once a host is located.

Direct Kinematic Analysis of a Hexapod Spider-Like Mobile Robot

2011 ◽  
Vol 403-408 ◽  
pp. 5053-5060 ◽  
Author(s):  
Mostafa Ghayour ◽  
Amir Zareei
Keyword(s):  
Angular Velocity ◽  
Mobile Robot ◽  
Time Variation ◽  
Kinematic Analysis ◽  
The Body ◽  
Specific Time ◽  
Centre Of Gravity ◽  
Joint Variable ◽  
Direct Kinematics ◽  
Robot Platform

In this paper, an appropriate mechanism for a hexapod spider-like mobile robot is introduced. Then regarding the motion of this kind of robot which is inspired from insects, direct kinematics of position and velocity of the centre of gravity (C.G.) of the body and noncontact legs are analysed. By planning and supposing a specific time variation for each joint variable, location and velocity of the C.G. of the robot platform and angular velocity of the body are obtained and the results are shown and analysed.

scholarly journals A faster escape does not enhance survival in zebrafish larvae

2017 ◽  
Vol 284 (1852) ◽  
pp. 20170359 ◽  
Author(s):  
Arjun Nair ◽  
Christy Nguyen ◽  
Matthew J. McHenry
Keyword(s):  
High Speed ◽  
Larval Fish ◽  
Body Position ◽  
Three Dimensional ◽  
Limited Range ◽  
The Body ◽  
Model Parameters ◽  
Fish Prey ◽  
Zebrafish Larvae ◽  
Fish Predators

An escape response is a rapid manoeuvre used by prey to evade predators. Performing this manoeuvre at greater speed, in a favourable direction, or from a longer distance have been hypothesized to enhance the survival of prey, but these ideas are difficult to test experimentally. We examined how prey survival depends on escape kinematics through a novel combination of experimentation and mathematical modelling. This approach focused on zebrafish ( Danio rerio ) larvae under predation by adults and juveniles of the same species. High-speed three-dimensional kinematics were used to track the body position of prey and predator and to determine the probability of behavioural actions by both fish. These measurements provided the basis for an agent-based probabilistic model that simulated the trajectories of the animals. Predictions of survivorship by this model were found by Monte Carlo simulations to agree with our observations and we examined how these predictions varied by changing individual model parameters. Contrary to expectation, we found that survival may not be improved by increasing the speed or altering the direction of the escape. Rather, zebrafish larvae operate with sufficiently high locomotor performance due to the relatively slow approach and limited range of suction feeding by fish predators. We did find that survival was enhanced when prey responded from a greater distance. This is an ability that depends on the capacity of the visual and lateral line systems to detect a looming threat. Therefore, performance in sensing, and not locomotion, is decisive for improving the survival of larval fish prey. These results offer a framework for understanding the evolution of predator–prey strategy that may inform prey survival in a broad diversity of animals.

Leg Lift During Non-Overconstrained Pseudo-Static Walking

1996 ◽  
Author(s):  
Chee K. Foo ◽  
Eugene F. Fichter ◽  
Becky L. Fichter
Keyword(s):  
Position Control ◽  
The Body ◽  
Degree Of Freedom ◽  
Walking Machine

Abstract A non-overconstrained pseudo-static walking machine has 1 leg joint under position control for every degree-of-freedom of the body. When 1 joint is position controlled on each of 6 legs, leg lift during a step results in 1 unregulated degree-of-freedom of the body. A second joint in one of the 5 legs that maintain contact with the ground must be switched to active position control at the same time that a foot is lifted. In theory any passively controlled joint in the 5 supporting legs may be chosen. However the requirement that no leg be in tension and practical limits on torques available from joint actuators severely restrict choice of both additional joint to actively position control and possible body positions where legs can be lifted.

scholarly journals The Body Position Spatial Task, a Test of Whole-Body Spatial Cognition: Comparison Between Adults With and Without Parkinson Disease

2018 ◽  
Vol 32 (11) ◽  
pp. 961-975 ◽  
Author(s):  
Jessica Battisto ◽  
Katharina V. Echt ◽  
Steven L. Wolf ◽  
Paul Weiss ◽  
Madeleine E. Hackney
Keyword(s):  
Parkinson Disease ◽  
Spatial Cognition ◽  
Body Position ◽  
Spatial Task ◽  
The Body ◽  
Whole Body

An Improved Body-Exact Method to Predict Large Amplitude Ship Roll Responses

2018 ◽  
Author(s):  
Rahul Subramanian ◽  
Naga Venkata Rakesh ◽  
Robert F. Beck
Keyword(s):  
Incident Wave ◽  
Large Amplitude ◽  
Nonlinear Models ◽  
Body Position ◽  
Computational Cost ◽  
Offshore Structures ◽  
The Body ◽  
Surface Boundary ◽  
Strip Theory ◽  
New Formulation

Accurate prediction of the roll response is of significant practical relevance not only for ships but also ship type offshore structures such as FPSOs, FLNGs and FSRUs. This paper presents a new body-exact scheme that is introduced into a nonlinear direct time-domain based strip theory formulation to study the roll response of a vessel subjected to moderately large amplitude incident waves. The free surface boundary conditions are transferred onto a representative incident wave surface at each station. The body boundary condition is satisfied on the instantaneous wetted surface of the body below this surface. This new scheme allows capturing nonlinear higher order fluid loads arising from the radiated and wave diffraction components. The Froude-Krylov and hydrostatic loads are computed on the intersection surface of the exact body position and incident wave field. The key advantage of the methodology is that it improves prediction of nonlinear hydrodynamic loads while keeping the additional computational cost small. Physical model tests have been carried out to validate the computational model. Fairly good agreement is seen. Comparisons of the force components with fully linear and body-nonlinear models help in bringing out the improvements due to the new formulation.

scholarly journals Embodiment of sleep-related words: evidence from event-related potentials

2020 ◽  
Author(s):  
Mareike J. Hülsemann ◽  
Björn Rasch
Keyword(s):  
Cognitive Processing ◽  
Word Processing ◽  
Body Position ◽  
Event Related Potentials ◽  
Event Related Potential ◽  
The Body ◽  
Semantic Meaning ◽  
Related Potentials ◽  
Multimodal Networks ◽  
Lying Down

AbstractOur thoughts, plans and intentions can influence physiological sleep, but the underlying mechanisms are unknown. According to the theoretical framework of “embodied cognition”, the semantic content of cognitive processes is represented by multimodal networks in the brain which also include body-related functions. Such multimodal representation could offer a mechanism which explains mutual influences between cognition and sleep. In the current study we tested whether sleep-related words are represented in multimodal networks by examining the effect of congruent vs. incongruent body positions on word processing during wakefulness.We experimentally manipulated the body position of 66 subjects (50 females, 16 males, 19-40 years old) between standing upright and lying down. Sleep- and activity-related words were presented around the individual speech recognition threshold to increase task difficulty. Our results show that word processing is facilitated in congruent body positions (sleep words: lying down and activity words: standing upright) compared with incongruent body positions, as indicated by a reduced N400 of the event-related potential (ERP) in the congruent condition with the lowest volume. In addition, early sensory components of the ERP (N180 and P280) were enhanced, suggesting that words were also acoustically better understood when the body position was congruent with the semantic meaning of the word. However, the difference in ERPs did not translate to differences on a behavioural level.Our results support the prediction of embodied processing of sleep- and activity-related words. Body position potentially induces a pre-activation of multimodal networks, thereby enhancing the access to the semantic concepts of words related to current the body position. The mutual link between semantic meaning and body-related function could be a key element in explaining influences of cognitive processing on sleep.

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