scholarly journals A Riemannian Geometry Theory of Synergy Selection for Visually-Guided Movement

Vision ◽  
2021 ◽  
Vol 5 (2) ◽  
pp. 26
Author(s):  
Peter D. Neilson ◽  
Megan D. Neilson ◽  
Robin T. Bye
Keyword(s):  
Riemannian Geometry ◽  
Degrees Of Freedom ◽  
Geometric Theory ◽  
Visual Space ◽  
Human Movement ◽  
The Body ◽  
Body Parts ◽  
Visually Guided ◽  
Visuomotor Task ◽  
Low Dimensional

Bringing together a Riemannian geometry account of visual space with a complementary account of human movement synergies we present a neurally-feasible computational formulation of visuomotor task performance. This cohesive geometric theory addresses inherent nonlinear complications underlying the match between a visual goal and an optimal action to achieve that goal: (i) the warped geometry of visual space causes the position, size, outline, curvature, velocity and acceleration of images to change with changes in the place and orientation of the head, (ii) the relationship between head place and body posture is ill-defined, and (iii) mass-inertia loads on muscles vary with body configuration and affect the planning of minimum-effort movement. We describe a partitioned visuospatial memory consisting of the warped posture-and-place-encoded images of the environment, including images of visible body parts. We depict synergies as low-dimensional submanifolds embedded in the warped posture-and-place manifold of the body. A task-appropriate synergy corresponds to a submanifold containing those postures and places that match the posture-and-place-encoded visual images that encompass the required visual goal. We set out a reinforcement learning process that tunes an error-reducing association memory network to minimize any mismatch, thereby coupling visual goals with compatible movement synergies. A simulation of a two-degrees-of-freedom arm illustrates that, despite warping of both visual space and posture space, there exists a smooth one-to-one and onto invertible mapping between vision and proprioception.

scholarly journals A Riemannian Geometry Theory of Three-Dimensional Binocular Visual Perception

Vision ◽  
2018 ◽  
Vol 2 (4) ◽  
pp. 43
Author(s):  
Peter Neilson ◽  
Megan Neilson ◽  
Robin Bye
Keyword(s):  
Riemannian Geometry ◽  
Vector Bundles ◽  
Three Dimensional ◽  
Geometric Theory ◽  
Visual Space ◽  
Human Movement ◽  
Image Features ◽  
Covariant Derivatives ◽  
Christoffel Symbols ◽  
Distance Relationship

We present a Riemannian geometry theory to examine the systematically warped geometry of perceived visual space attributable to the size–distance relationship of retinal images associated with the optics of the human eye. Starting with the notion of a vector field of retinal image features over cortical hypercolumns endowed with a metric compatible with that size–distance relationship, we use Riemannian geometry to construct a place-encoded theory of spatial representation within the human visual system. The theory draws on the concepts of geodesic spray fields, covariant derivatives, geodesics, Christoffel symbols, curvature tensors, vector bundles and fibre bundles to produce a neurally-feasible geometric theory of visuospatial memory. The characteristics of perceived 3D visual space are examined by means of a series of simulations around the egocentre. Perceptions of size and shape are elucidated by the geometry as are the removal of occlusions and the generation of 3D images of objects. Predictions of the theory are compared with experimental observations in the literature. We hold that the variety of reported geometries is accounted for by cognitive perturbations of the invariant physically-determined geometry derived here. When combined with previous description of the Riemannian geometry of human movement this work promises to account for the non-linear dynamical invertible visual-proprioceptive maps and selection of task-compatible movement synergies required for the planning and execution of visuomotor tasks.

scholarly journals A Novel Self-Intersection Penalty Term for Statistical Body Shape Models and Its Applications in 3D Pose Estimation

2019 ◽  
Vol 9 (3) ◽  
pp. 400 ◽  
Author(s):  
Zaiqiang Wu ◽  
Wei Jiang ◽  
Hao Luo ◽  
Lin Cheng
Keyword(s):  
Pose Estimation ◽  
Body Shape ◽  
The Body ◽  
The Self ◽  
Body Parts ◽  
3D Pose Estimation ◽  
Penalty Term ◽  
Partial Derivatives ◽  
Shape Models ◽  
Low Dimensional

Statistical body shape models are widely used in 3D pose estimation due to their low-dimensional parameters representation. However, it is difficult to avoid self-intersection between body parts accurately. Motivated by this fact, we proposed a novel self-intersection penalty term for statistical body shape models applied in 3D pose estimation. To avoid the trouble of computing self-intersection for complex surfaces like the body meshes, the gradient of our proposed self-intersection penalty term is manually derived from the perspective of geometry. First, the self-intersection penalty term is defined as the volume of the self-intersection region. To calculate the partial derivatives with respect to the coordinates of the vertices, we employed detection rays to divide vertices of statistical body shape models into different groups depending on whether the vertex is in the region of self-intersection. Second, the partial derivatives could be easily derived by the normal vectors of neighboring triangles of the vertices. Finally, this penalty term could be applied in gradient-based optimization algorithms to remove the self-intersection of triangular meshes without using any approximation. Qualitative and quantitative evaluations were conducted to demonstrate the effectiveness and generality of our proposed method compared with previous approaches. The experimental results show that our proposed penalty term can avoid self-intersection to exclude unreasonable predictions and improves the accuracy of 3D pose estimation indirectly. Further more, the proposed method could be employed universally in triangular mesh based 3D reconstruction.

scholarly journals The effects of surface compliance on greyhound galloping dynamics

2019 ◽  
Vol 233 (4) ◽  
pp. 1033-1043 ◽  
Author(s):  
Hasti Hayati ◽  
David Eager ◽  
Paul Walker
Keyword(s):  
Degrees Of Freedom ◽  
Surface Composition ◽  
Substrate Surface ◽  
The Body ◽  
Body Parts ◽  
Contributing Factors ◽  
Life Threatening ◽  
Track Surface ◽  
The Right ◽  
Single Support Phase

Greyhounds are the fastest breed of dog and can reach a speed up to 68 km/h. These racing animals sustain unique injuries seldom seen in other breeds of dog. The highest rate of life-threatening injuries in these dogs is hock fracture, mostly of the right hind-leg. One of the main injury contributing factors in this sport is the track surface. There are some studies into the ideal track surface composition for greyhound racing but almost no study has investigated the body–surface interaction. Accordingly, the purpose of this work is to study the effect of surface compliance on the galloping dynamics of greyhounds during the hind-leg single-support phase which is a critical phase in hock injuries. Thus, a three degrees-of-freedom model for the greyhound body and substrate surface is designed using spring-loaded inverted pendulum method. The results showed that forces acting on the hind-leg were substantially affected when the surface compliance altered from the relatively hard (natural grass) to a relatively soft surface (synthetic rubber). The main contribution of this work is designing a mathematical model to predict the dynamics of the hock and the hind-leg as the most vulnerable body parts in greyhounds. Furthermore, this model can be used to optimise the greyhound track surface composition and therefore improve the safety and welfare within the greyhound racing industry.

Balance Maintaining by Human

2016 ◽  
Vol 248 ◽  
pp. 155-160
Author(s):  
Andrzej Kot ◽  
Agata Nawrocka
Keyword(s):  
Nervous System ◽  
Human Body ◽  
Degrees Of Freedom ◽  
Inverted Pendulum ◽  
Balance Control ◽  
Human Motion ◽  
The Body ◽  
Posture Control ◽  
Body Parts ◽  
Receptor System

Harmonious cooperation of the skeletal, muscular and nervous systems, forming a human motion organ, is responsible for all undertaken movement activities. Motion organ in the illustrated embodiment responsible not only for two basic motion activities, locomotion and manipulation, but also for maintaining the posture of the human body. Standing posture control makes a particular dimension of physical activity, because correct, stable posture determines the ability to perform most human movements. In the case of a man to maintain a balance in a standing position seems to be something obvious and does not require much effort, but with the advent of lesions or aging we begin to see how complex it is the process of balance control. The changes lead to impaired balance control which in turn can lead to the appearance of postural instability and in extreme circumstances, even to collapse. Maintaining a stable posture it is primarily associated with motor control provided by the human nervous system. The nervous system acts as an posture control system and most of all giving to a body well-defined silhouette. This control relies heavily on the integration of information from the human receptor system. Muscle, joint, tendon and skin receptors communicate first to the brain information about the movement and position of individual body parts and then feedback these signals to the muscles, causing reflex reactions allowing for correction of posture and thus return the center of gravity to a position that maintaining equilibrium. Subdivide those human body into segments linked closely with the system osteoarthritis limbs and trunk can create a system of interconnected pendulums with many degrees of freedom. In the case of standing it will be largely complicated inverted pendulums system by which activities phenomena associated with maintaining balance and locomotion can be modeled. If additionally in an upright position, taking into account the natural motion restrictions movements in all joints except the ankles will be blocked, the body will be a close approximation behave like a rigid body. So we can assume that for supporting the human body at the ankle, it will behave like an inverted pendulum. The article presents the ways of describing the equilibrium of man as an inverted pendulum.

scholarly journals Running Form Analysis Based on Impact Dynamics: A Minimally Complex Mechanical Model

2018 ◽  
Vol 63 (1) ◽  
pp. 7-15 ◽  
Author(s):  
László Bencsik ◽  
Ambrus Zelei
Keyword(s):  
Degrees Of Freedom ◽  
Biomechanical Model ◽  
Total Body Weight ◽  
The Body ◽  
Body Parts ◽  
Form Analysis ◽  
Biomechanical Models ◽  
Foot Strike ◽  
Low Degrees ◽  
The Impact

Biomechanical models of different complexity are used to understand the dynamics of human running. Low degrees-of-freedom models are appropriate for the prediction of the effect of certain parameter changes. We present a minimally complex biomechanical model which characterizes the effects of foot strike pattern and shank angle on the ground-foot impact intensity, which influences the risk of injuries and energy efficiency.A three segment leg model (thigh, shank and foot) is proposed combined with the mass of the rest of the body parts concentrated in the hip. The ground-foot impact intensity and the absorbed kinetic energy are analyzed using multibody dynamics tools. The impact intensity was discovered in the parameter space of the angle of the thigh, the angle of the shank, the foot strike pattern and the running speed.The results regarding the effect of strike pattern are in coincidence with the literature: forefoot strike implies lower impact intensity and energy absorption than rearfoot strike. However, in contrast of the previous result of a two segment foot model from the related literature, the calculations indicated that the shank angle highly affects the impact intensity: the impact intensity can be reduced by foot touchdown under the hip. We showed that foot and shank cannot be analyzed in itself without considering the thigh and the total body weight, and we also confirmed that the horizontal velocity cannot be neglected when foot impact is analyzed.

The Visual Simulation Analysis of Human Body Movement Model

2014 ◽  
Vol 556-562 ◽  
pp. 3913-3916
Author(s):  
Jun Jie Wang
Keyword(s):  
Human Body ◽  
Simulation Analysis ◽  
Body Movement ◽  
Linear Optimization ◽  
Human Movement ◽  
The Body ◽  
Body Parts ◽  
Optimization Strategy ◽  
Matching Accuracy ◽  
Movement Model

This paper proposes the re-built human body movement model with multiple cameras. In the tracking frame of the non-linear optimization strategy, the paper builds the body dynamic model to dynamically simulate the human movement which effectively solves the issues of the body parts overlap and tracking errors accumulate. Compared with traditional methods, the required equipment is very economic and the matching accuracy of the algorithm is quite high. The paper applies the athletes as the experimental examples which illustrate the proposed algorithm can effectively increase the 3D image tracking matching accuracy in dynamic videos as the analysis basis.

Representing utility and deploying the body

2020 ◽  
Vol 43 ◽  
Author(s):  
David Spurrett
Keyword(s):  
Functional Activity ◽  
Degrees Of Freedom ◽  
The Body ◽  
Target Article ◽  
Processing Demands ◽  
The Many

Abstract Comprehensive accounts of resource-rational attempts to maximise utility shouldn't ignore the demands of constructing utility representations. This can be onerous when, as in humans, there are many rewarding modalities. Another thing best not ignored is the processing demands of making functional activity out of the many degrees of freedom of a body. The target article is almost silent on both.

Formulation, Design and Development of Niosome Based Topical Gel for Skin Cancer

2017 ◽  
Vol 2 (3) ◽  
Keyword(s):  
Skin Cancer ◽  
Drug Release ◽  
Hemorrhagic Cystitis ◽  
The Body ◽  
Cancer Drug ◽  
Inversion Method ◽  
Body Parts ◽  
Basal Cells ◽  
Formulation Design ◽  
Topical Gel

Melanoma is the most dangerous type of skin cancer in which mostly damaged unpaired DNA starts mutating abnormally and staged an unprecedented proliferation of epithelial skin to form a malignant tumor. In epidemics of skin, pigment-forming melanocytes of basal cells start depleting and form uneven black or brown moles. Melanoma can further spread all over the body parts and could become hard to detect. In USA Melanoma kills an estimated 10,130 people annually. This challenge can be succumbed by using the certain anti-cancer drug. In this study design, cyclophosphamide were used as a model drug. But it has own limitation like mild to moderate use may cause severe cytopenia, hemorrhagic cystitis, neutropenia, alopecia and GI disturbance. This is a promising challenge, which is caused due to the increasing in plasma drug concentration above therapeutic level and due to no rate limiting steps involved in formulation design. In this study, we tried to modify drug release up to threefold and extended the release of drug by preparing and designing niosome based topical gel. In the presence of Dichloromethane, Span60 and cholesterol, the initial niosomes were prepared using vacuum evaporator. The optimum percentage drug entrapment efficacy, zeta potential, particle size was found to be 72.16%, 6.19mV, 1.67µm.Prepared niosomes were further characterized using TEM analyzer. The optimum batch of niosomes was selected and incorporated into topical gel preparation. Cold inversion method and Poloxamer -188 and HPMC as core polymers, were used to prepare cyclophosphamide niosome based topical gel. The formula was designed using Design expert 7.0.0 software and Box-Behnken Design model was selected. Almost all the evaluation parameters were studied and reported. The MTT shows good % cell growth inhibition by prepared niosome based gel against of A375 cell line. The drug release was extended up to 20th hours. Further as per ICH Q1A (R2), guideline 6 month stability studies were performed. The results were satisfactory and indicating a good formulation approach design was achieved for Melanoma treatment.

Re-imagining Reproduction: Unsettling Metaphors in the History of Imperial Science and Commercial Surrogacy in India

Somatechnics ◽  
2015 ◽  
Vol 5 (1) ◽  
pp. 88-103 ◽  
Author(s):  
Kalindi Vora
Keyword(s):  
Assisted Reproductive Technologies ◽  
Reproductive Technologies ◽  
The Body ◽  
Body Parts ◽  
Colonial History ◽  
Women's Bodies ◽  
Commercial Surrogacy ◽  
Art Practices ◽  
History Of ◽  
Travel Industry

This paper provides an analysis of how cultural notions of the body and kinship conveyed through Western medical technologies and practices in Assisted Reproductive Technologies (ART) bring together India's colonial history and its economic development through outsourcing, globalisation and instrumentalised notions of the reproductive body in transnational commercial surrogacy. Essential to this industry is the concept of the disembodied uterus that has arisen in scientific and medical practice, which allows for the logic of the ‘gestational carrier’ as a functional role in ART practices, and therefore in transnational medical fertility travel to India. Highlighting the instrumentalisation of the uterus as an alienable component of a body and subject – and therefore of women's bodies in surrogacy – helps elucidate some of the material and political stakes that accompany the growth of the fertility travel industry in India, where histories of privilege and difference converge. I conclude that the metaphors we use to structure our understanding of bodies and body parts impact how we imagine appropriate roles for people and their bodies in ways that are still deeply entangled with imperial histories of science, and these histories shape the contemporary disparities found in access to medical and legal protections among participants in transnational surrogacy arrangements.

Deadlift Recognition and Application based on Multiple Modalities using Recurrent Neural Network

2020 ◽  
Vol 2020 (17) ◽  
pp. 2-1-2-6
Author(s):  
Shih-Wei Sun ◽  
Ting-Chen Mou ◽  
Pao-Chi Chang
Keyword(s):  
Neural Network ◽  
Recurrent Neural Network ◽  
Network Structure ◽  
Inertial Sensors ◽  
Body Movement ◽  
The Body ◽  
Body Parts ◽  
Multimodal Sensing ◽  
Multiple Devices ◽  
Neural Network Structure

To improve the workout efficiency and to provide the body movement suggestions to users in a “smart gym” environment, we propose to use a depth camera for capturing a user’s body parts and mount multiple inertial sensors on the body parts of a user to generate deadlift behavior models generated by a recurrent neural network structure. The contribution of this paper is trifold: 1) The multimodal sensing signals obtained from multiple devices are fused for generating the deadlift behavior classifiers, 2) the recurrent neural network structure can analyze the information from the synchronized skeletal and inertial sensing data, and 3) a Vaplab dataset is generated for evaluating the deadlift behaviors recognizing capability in the proposed method.

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