Postural Modes Research Articles

Design and Optimization of Multifunctional Human Motion Rehabilitation Training Robot EEGO

A multifunctional human motion rehabilitation training robot named EEGO (electric easy go) that could achieve four functions through structural transformation was designed. The four functions achieved by four working modes: the Supporting Posture Mode (SM), the Grasping Posture Mode (GM), the Riding Posture Mode (RM), and the Pet Mode (PM), which are suitable for patients in the middle and late stages of rehabilitation. The size of the equipment under different functions is determined by the height of different postures of the human. During the design process, the equipment was lightweight using size optimization methods, resulting in a 47.3% reduction in mass compared to the original design. Based on the Zero Moment Point (ZMP) stability principle, the stability mechanism of the robot was verified under the three different functions. According to the wanted function of the equipment, the control system of the equipment was designed. Finally, a prototype was prepared based on the analysis and design results for experimental verification, which can effectively assist patients in motion rehabilitation training such as gait, walking, and other movements.

Self-organizing neural network for reproducing human postural mode alternation through deep reinforcement learning

A self-organized phenomenon in postural coordination is essential for understanding the auto-switching mechanism of in-phase and anti-phase postural coordination modes during standing and related supra-postural activities. Previously, a model-based approach was proposed to reproduce such self-organized phenomenon. However, if we set this problem including the process of how we establish the internal predictive model in our central nervous system, the learning process is critical to be considered for establishing a neural network for managing adaptive postural control. Particularly when body characteristics may change due to growth or aging or are initially unknown for infants, a learning capability can improve the hyper-adaptivity of human motor control for maintaining postural stability and saving energy in daily living. This study attempted to generate a self-organizing neural network that can adaptively coordinate the postural mode without assuming a prior body model regarding body dynamics and kinematics. Postural coordination modes are reproduced in head-target tracking tasks through a deep reinforcement learning algorithm. The transitions between the postural coordination types, i.e. in-phase and anti-phase coordination modes, could be reproduced by changing the task condition of the head tracking target, by changing the frequencies of the moving target. These modes are considered emergent phenomena existing in human head tracking tasks. Various evaluation indices, such as correlation, and relative phase of hip and ankle joint, are analyzed to verify the self-organizing neural network performance to produce the postural coordination transition between the in-phase and anti-phase modes. In addition, after learning, the neural network can also adapt to continuous task condition changes and even to unlearned body mass conditions keeping consistent in-phase and anti-phase mode alternation.

Recognition of Human Motion Intentions Based on Bayesian-Optimized XGBOOST Algorithm

In order to improve the recognition rate for lower extremity motion patterns, this study designs a recognition method for such patterns, which integrates electromyography (EMG) and inertial measurement unit (IMU) signals in three posture modes, including walking on the ground, squatting, and extending seated legs, to address the difficulty with obtaining high signal-to-noise ratio EMG and IMU signals synchronously. Besides, this study proposes a synchronous analysis method for EMG and IMU dual-mode information to correct antipower frequency interference accelerometer signals. The collected signals are preprocessed to extract eigenvalues. And by using the kernel principal component analysis (KPCA), the information on these eigenvalues is fused. Finally, according to the characteristics of the data, a Bayesian-optimized XGBOOST algorithm is designed. Lower-limb movement patterns are classified with the feature vector put into the optimization algorithm. Multiperson experimental results show that the average recognition accuracy for different poses can reach 94.42%, the average F 1 value 95.33%, and the average return value 95.68%, proving that the model proposed can be used to identify human motion intentions and its generalization ability can detect individual differences in human bodies.

Positional Behavior and Substrate Use in Wild Tibetan Macaques.

Simple SummaryBody size and individual development are essential factors that affect primate movement through the canopy and access to food. However, only a few studies have been conducted on immature wild macaques. Although adults are significantly heavier than the other age groups, this study found that they did not exhibit higher frequencies of climbing and bridging. Jumps and suspensions were more frequent in juveniles than adults. We also found that juveniles exhibited rare behaviors during play, such as cling locomotion, suspensory locomotion, and bounding. We hypothesized that juveniles would exhibit diverse positional behaviors associated with altered skeletal muscle development. Diverse positional abilities facilitate habitat exploitation and the avoidance of danger.Body size and individual development significantly affect positional behavior and substrate use. However, only a few studies have been conducted on immature wild macaques. We studied wild Tibetan macaques (Macaca thibetana) inhabiting Mt. Huangshan, China, to explore the degree of interspecific variation in positional behavior in relation to body weight and individual development. From September 2020 to August 2021, we used instantaneous scan sampling (duration 5 min, interval 10 min) to record age–sex groups, locomotions, postures, and substrate attributes. The results showed that Tibetan macaques used terrestrial substrates in nearly two-thirds of the recorded observations. The main postural modes were sitting and quadrupedal standing. The main locomotor modes were quadrupedal walking and climbing among all age–sex group records. Positional behavior and substrate use in adults only significantly differed from those in juveniles and infants. Although adult males were larger than the other age–sex groups, they did not climb and bridge more frequently than the other age–sex groups. The frequency of climbing, leaping, and suspension was significantly higher in juveniles than in adults. In addition, adult males used terrestrial and larger substrates more frequently, while juveniles and infants used arboreal substrates and terminals more frequently than adult males during traveling and feeding. We hypothesize that the more positional behavioral spectrum of Tibetan macaque juveniles’ may be related to rapid skeletal muscle development. These results suggest that differences in interspecific positional behavior may be caused by the individual development and survival needs of individuals, rather than just body size.

Breathing pattern, orthognathic surgery and head posture in dentofacial deformity

Abstract Introduction: Dentofacial deformity (DFD) and the breathing mode can change the head posture. However, head posture changes after orthognathic surgery are controversial, and no studies were found on the relationship between the head posture and breathing mode in adults with DFD. Objective: To identify the main head posture changes in young adults affected by DFD, to verify if orthognathic surgery modifies the breathing mode and head posture, and if the breathing mode is associated with the head posture. Methods: Twenty-five young adults were assessed and divided in dentofacial deformity group (DFD; n = 15; x̅ = 28 years) and control group with dentofacial harmony (CG; n = 10; balanced by gender and age with the study group). Breathing mode was evaluated according to the orofacial myofunctional evaluation protocol, and biophotogrammetry was used in the head posture analyses. For the DFD group, the evaluations were performed pre and post the orthognathic surgery (pre- and post-DFD). Results: For the DFD group, the breathing mode modified after orthognathic surgery (p = 0.003), but with difference from GC (p = 0.027). No changes were found in head posture after orthognathic surgery, but significant difference was seen between post-DFD and GC for head inclination (p = 0.017). No relationship was observed between breathing mode and head posture (p > 0.05). Conclusion: After orthognathic surgery, a spontaneous improvement of breathing was seen in the sample. It was not possible to verify changes in head posture and association with breathing mode and head posture.

Multiparameter study of the physiological reactions of the human organism to complex postural loads

BACKGROUND: Reactions of human cardiovascular system to complex dynamic postural loads were under investigation by previous authors. Individual limiting mode of postural loads, i.e. alternating negative-positive periodic changes of body position angle on tilting table with regard to clinostatic position, was defined. It was demonstrated that application of oscillatory passive dynamic postural loads can cause certain hemodynamic reactions, which expression depend on postural loads dynamic characteristics and subjects primary state.
 AIM: Aim of the study is to develop comprehensive methodology (practice) that explores regulation mechanisms of cardiovascular, respiratory, central and autonomic nervous systems and their reactions to physiological strains with assigned properties (intensity, direction, periodicity and duration of postural loads).
 MATERIALS AND METHODS: 30 young healthy participants took part in the study. Physiological indicators were registered in dynamic mode synchronously with trajectory of participants motion. This study implemented common statistical methods as much as original means of analysis by integrating theory of dynamic systems.
 RESULTS: Evaluation of synchronously registered physiological indicators by means of instrumental and software application, in particular, postural loads protocols of various intensity and motion direction, showed that oscillatory passive dynamic postural mode allows considerable improvements in overall blood circulation and gas exchange in the lungs. These changes constitute in a rise of systemic and local blood flow without significant shift of arterial pressure, increased frequency of heartbeats and respiratory rate.
 CONCLUSIONS: Continuous monitoring of participants condition during complex postural loads give an opportunity for studying a set of physiological reactions and has a future implication in scientifically approved recommendations that describe practical use of postural loads as a correction technology for human health state and training.

Fusing Hand Postures and Speech Recognition for Tasks Performed by an Integrated Leg–Arm Hexapod Robot

Hand postures and speech are convenient means of communication for humans and can be used in human–robot interaction. Based on structural and functional characteristics of our integrated leg-arm hexapod robot, to perform reconnaissance and rescue tasks in public security application, a method of linkage of movement and manipulation of robots is proposed based on the visual and auditory channels, and a system based on hand postures and speech recognition is described. The developed system contains: a speech module, hand posture module, fusion module, mechanical structure module, control module, path planning module and a 3D SLAM (Simultaneous Localization and Mapping) module. In this system, three modes, i.e., the hand posture mode, speech mode, and a combination of the hand posture and speech modes, are used in different situations. The hand posture mode is used for reconnaissance tasks, and the speech mode is used to query the path and control the movement and manipulation of the robot. The combination of the two modes can be used to avoid ambiguity during interaction. A semantic understanding-based task slot structure is developed by using the visual and auditory channels. In addition, a method of task planning based on answer-set programming is developed, and a system of network-based data interaction is designed to control movements of the robot using Chinese instructions remotely based on a wide area network. Experiments were carried out to verify the performance of the proposed system.

Manual dexterity of mice during food-handling involves the thumb and a set of fast basic movements.

The small first digit (D1) of the mouse's hand resembles a volar pad, but its thumb-like anatomy suggests ethological importance for manipulating small objects. To explore this possibility, we recorded high-speed close-up video of mice eating seeds and other food items. Analyses of ethograms and automated tracking with DeepLabCut revealed multiple distinct microstructural features of food-handling. First, we found that mice indeed made extensive use of D1 for dexterous manipulations. In particular, mice used D1 to hold food with either of two grip types: a pincer-type grasp, or a "thumb-hold" grip, pressing with D1 from the side. Thumb-holding was preferentially used for handling smaller items, with the smallest items held between the two D1s alone. Second, we observed that mice cycled rapidly between two postural modes while feeding, with the hands positioned either at the mouth (oromanual phase) or resting below (holding phase). Third, we identified two highly stereotyped D1-related movements during feeding, including an extraordinarily fast (~20 ms) "regrip" maneuver, and a fast (~100 ms) "sniff" maneuver. Lastly, in addition to these characteristic simpler movements and postures, we also observed highly complex movements, including rapid D1-assisted rotations of food items and dexterous simultaneous double-gripping of two food fragments. Manipulation behaviors were generally conserved for different food types, and for head-fixed mice. Wild squirrels displayed a similar repertoire of D1-related movements. Our results define, for the mouse, a set of kinematic building-blocks of manual dexterity, and reveal an outsized role for D1 in these actions.

Основные средства формирования и коррекции постуральных механизмов у дошкольников с нарушениями опорно-двигательного аппарата

The article investigated the problem of using the basic means for the formation and correction of postural mechanisms in preschool children with musculoskeletal system disorder. First of all, this refers to the means of physical education, i.e. special exercises performed by the child independently or under the guidance of a teacher. As the basis for the exercises selection and systematization was taken ontogenetic principle of the biological systems sequential formation of child's body, which are part of the postural aplomb system (vestibular, visual, proprioceptive and oculomotor).Exactly the basis of this ontogenetically predetermined sequence of the necessary equilibrium system structures formation were selected and classified that sections of corrective physical exercises aimed at purposeful development and correction of the balance function in preschool age children with movement disorders. Among them were the following sections: vestibular exercises without visual control, vestibular-visual exercises, vestibular-visual-supporting-rectifying exercises, vestibular-visual-proprioceptive-supporting exercises and exercises for oculomotor function. In the classification of the development means and equilibrium function correction in preschoolers, the principle of amplification was applied, when the following more perfect one was added to each previous in the ontogenetic function of postural aplomb, the next more perfect one was added and so on until the complete integration of exercises reflecting the training of all five channels of the postural aplomb system of the child. To improve the equilibrium function of the child, then these exercises can be formed into specially organized postural modes, depending on the characteristics of postural deficiency in an individual child or a typological subgroup of children. Particular attention is paid in the article to stabilometric training based on biological feedback in the process of implementing the corresponding training games using the stabilometric platform “Stabilan”. It is final phase of the equilibrium function training that makes it possible to most effectively integrate the activities of all five channels of the postural aplomb system to ensure stable dynamic stability of the child. Key words: physical exercises, postural mechanism, correction, postural motor mode, preschool children.

Kinematic and Kinetostatic Analysis of Parallel Manipulators with Emphasis on Position, Motion, and Actuation Singularities

SummaryThis paper provides a contribution to the singularity analysis of the parallel manipulators by introducing the position singularities in addition to the motion and actuation singularities. The motion singularities are associated with the linear velocity mapping between the task and joint spaces. So, they are the singularities of the relevant Jacobian matrices. On the other hand, the position singularities are associated with the nonlinear position mapping between the task and joint spaces. So, they are encountered in the position-level solutions of the forward and inverse kinematics problems. In other words, they come out irrespective of the velocity mapping and the Jacobian matrices. Considering these distinctions, a kinematic singularity is denoted here by one of the four acronyms, which are PSFK (position singularity of forward kinematics), PSIK (position singularity of inverse kinematics), MSFK (motion singularity of forward kinematics), and MSIK (motion singularity of inverse kinematics). There may also occur an actuation singularity (ACTS) concerning the kinetostatic relationships that involve forces and moments. However, it is verified that an ACTS is the same as an MSFK. Each singularity induces different consequences in the joint and task spaces. A PSFK imposes a constraint on the active joint variables and makes the end-effector position indefinite and uncontrollable. Therefore, it must be avoided. An MSFK imposes a constraint on the rates of the active joint variables and makes the end-effector motion indefinite and easily perturbable. Besides, since it is also an ACTS, it causes the actuator torques or forces to grow without bound. Therefore, it must also be avoided. On the other hand, a PSIK imposes a constraint on the end-effector position but provides freedom for the active joint variables. Similarly, an MSIK imposes a constraint on the end-effector motion but provides freedom for the rates of the active joint variables. A PSIK or MSIK need not be avoided if the constraint it imposes on the position or motion of the end-effector is acceptable or if the task can be planned to be compatible with that constraint. Besides, with such a compatible task, a PSIK or MSIK may even be advantageous, because the freedom it provides for the active joint variables can sometimes be used for a secondary purpose. This paper is also concerned with the multiplicities of forward kinematics in the assembly modes of the manipulator and the multiplicities of inverse kinematics in the posture modes of the legs. It is shown that the assembly mode changing poses of the manipulator are the same as the MSFK poses, and the posture mode changing poses of the legs are the same as the MSIK poses.

Three-dimensional behavioural phenotyping of freely moving C. elegans using quantitative light field microscopy.

Behavioural phenotyping of model organisms is widely used to investigate fundamental aspects of organism biology, from the functioning of the nervous system to the effects of genetic mutations, as well as for screening new drug compounds. However, our capacity to observe and quantify the full range and complexity of behavioural responses is limited by the inability of conventional microscopy techniques to capture volumetric image information at sufficient speed. In this article we describe how combining light field microscopy with computational depth estimation provides a new method for fast, quantitative assessment of 3D posture and movement of the model organism Caenorhabditis elegans (C. elegans). We apply this technique to compare the behaviour of cuticle collagen mutants, finding significant differences in 3D posture and locomotion. We demonstrate the ability of quantitative light field microscopy to provide new fundamental insights into C. elegans locomotion by analysing the 3D postural modes of a freely swimming worm. Finally, we consider relative merits of the method and its broader application for phenotypic imaging of other organisms and for other volumetric bioimaging applications.

Effect of body mass distribution on the ontogeny of positional behaviors in non-human primates: Longitudinal follow-up of infant captive olive baboons (Papio anubis).

The diversity of primates' positional capabilities is unique among mammals. Indeed, they exhibit a daily repertoire composed of various locomotor and postural modes that may be linked to their particular morphological pattern. Because ontogeny undergoes parallel behavioral and morphological modifications, it may be useful to investigate the biomechanical consequences of the changing body shape. We, therefore, collected accurate quantitative and longitudinal data on positional behaviors, body mass distribution patterns, activities, and environment on a sample of six infant olive baboons, Papio anubis. These baboons are kept at the Primatology Station of the CNRS, France, where they live within the same social group. Individual behaviors were quantified using the focal sampling method. The body mass distribution was estimated according to a geometric model based on direct external measurements. Multivariate analysis enabled us to analyze the interactions between the data. Our results show that body mass distribution changes together with the ontogenetic changes in positional behaviors. At an early age, individuals have distally heavy segment masses in the limbs and an important fraction of the behavioral repertoire involves efficient grasping abilities. At the end of infancy, the same individuals have relatively more mass in proximal segments of the limbs and the proportion of quadrupedal walking is significantly higher while other climbing and suspensory behaviors decreased substantially. The present study experimentally confirms the association between body mass distribution and the positional repertoire of primates. These relationships, when interpreted in the context of basic biomechanical concepts, may improve our understanding of primate locomotion. We discuss further the implications of these functional relationships when modeling the evolutionary pathway of primates. Am. J. Primatol. 78:1201-1221, 2016. © 2016 Wiley Periodicals, Inc.

Integrating locomotion, postures and morphology: The case of the tayra, Eira barbara (Carnivora, Mustelidae)

Locomotion and postures are key factors to understanding the biology of animals. However, scansorial and arboreal carnivorans remain poorly studied regarding these issues. Herein, we present a behavioral and morphological analysis of the arboreal locomotion of the tayra (Eira barbara), a neotropical forest-dwelling mustelid. Data on habitat use and locomotor and postural modes were collected from free-ranging tayras in a terra-firme forest in French Guiana. Additionally, qualitative morphological traits and linear measurements of the girdles and appendicular skeleton were analyzed through comparative anatomical descriptions, univariate tests, and a principal components and discriminant analysis. Tayras frequently used clambering, quadrupedal walking, claw climbing and quadrupedal standing, performed primarily on small and medium, oblique and horizontal branches. Furthermore, our morpho-functional analyses revealed that tayras possess autopodial specializations for navigating on arboreal substrates, while the more proximal elements present features more similar to other terrestrial or scansorial mustelids, and theoretically less modified from the hypothetical weasel-like ancestor of mustelids. This mosaic of morphological features of the tayra, a combination of phylogenetic inertia and ecological signals, very likely evolved to promote the efficient and effective exploitation of diverse habitats and resources in this versatile species.

Design and Test of a Hybrid Foot Force Sensing and GPS System for Richer User Mobility Activity Recognition

Wearable and accompanied sensors and devices are increasingly being used for user activity recognition. However, typical GPS-based and accelerometer-based (ACC) methods face three main challenges: a low recognition accuracy; a coarse recognition capability, i.e., they cannot recognise both human posture (during travelling) and transportation mode simultaneously, and a relatively high computational complexity. Here, a new GPS and Foot-Force (GPS + FF) sensor method is proposed to overcome these challenges that leverages a set of wearable FF sensors in combination with GPS, e.g., in a mobile phone. User mobility activities that can be recognised include both daily user postures and common transportation modes: sitting, standing, walking, cycling, bus passenger, car passenger (including private cars and taxis) and car driver. The novelty of this work is that our approach provides a more comprehensive recognition capability in terms of reliably recognising both human posture and transportation mode simultaneously during travel. In addition, by comparing the new GPS + FF method with both an ACC method (62% accuracy) and a GPS + ACC based method (70% accuracy) as baseline methods, it obtains a higher accuracy (95%) with less computational complexity, when tested on a dataset obtained from ten individuals.

Bipedal Behaviour in Olive Baboons: Infants versus Adults in a Captive Environment

The olive baboon is described as a committed quadrupedal primate. However, available data show that they actually use a variety of locomotor and postural modes. Bipedalism is observed occasionally but spontaneously in captivity and in the wild. As observed in other Catarrhini, immature baboons appear to be more bipedal than adults: this study aims to provide the necessary quantitative data to support this hypothesis, as none has been available so far. The locomotor and postural repertoire was quantified for two age classes: infants beginning to forage independently, and adults. Our results show that infants appear to have a wider repertoire than adults, and bipedal postures and locomotion in infants, although infrequent, appear to distinguish them clearly from adults. In captivity, behavioural context and morphology are the two main factors that could explain age-related positional differences, given a constant ecological context.

Positional behavior and substrate use of Micromys minutus (Rodentia: Muridae): Insights for understanding primate origins

Several hypotheses have been proposed to explain the origins of primates, suggesting evolutionary scenarios that are usually paralleled to modern mammalian models that partly simulate the morpho-behavioral apomorphies of primates. The current study examines substrate use and positional behavior of tiny-sized Eurasian harvest mice (Micromys minutus) as living models for inferring the evolution of versatile behavior, flexible branch use and pedal grasping in early small-sized primates. Micromys exhibits a diverse locomotor repertoire composed of clambering and climbing, and uses postural modes requiring secure pedal grasping. It also makes considerable use of fine flexible substrates of various inclinations during both feeding/foraging and traveling. This profile seems to represent an intermediate step between stage 2 (Tupaia-stage) and stage 3 (Caluromys-stage) in Sargis et al.'s (2007) primate evolutionary scenario. Furthermore, our findings suggest that tiny size in itself brings a unique level of flexibility in posture and locomotion that has heretofore been underappreciated in the primate evolution literature.

Expression of Myosin Heavy Chain Isoforms in the Supraspinatus Muscle of Different Primate Species: Implications for the Study of the Adaptation of Primate Shoulder Muscles to Different Locomotor Modes

The supraspinatus muscle is a key component of the soft tissues of the shoulder. In pronograde primates, its main function, in combination with the other rotator cuff muscles (subscapularis, infraspinatus, and teres minor), is to stabilize the glenohumeral joint, whereas in orthograde primates it functions together with the deltoid, to elevate the upper extremity in the scapular plane. To determine whether these functional differences are also reflected in the molecular biochemistry of the supraspinatus muscles involved in these different locomotor modes, we used real-time polymerase chain reaction (RT-PCR) to analyze the expression of the myosin heavy chain (MHC) isoforms in supraspinatus muscles from modern humans and 12 species of pronograde and orthograde primates. The MHC expression pattern in the supraspinatus muscle of pronograde primates was consistent with its function as a tonic and postural muscle, whereas the MHC expression pattern observed in the supraspinatus muscle of nonhuman orthograde primates was that of a muscle that emphasizes speed, strength, and less resistance to fatigue. These findings are consistent with the role of the supraspinatus in the posture and locomotor modes of these groups of nonhuman primates. The humans included in the study had an expression pattern similar to that of the nonhuman orthograde primates. In conclusion, molecular analysis of skeletal muscles via RT-PCR can contribute to a better understanding of the morphological and functional characteristics of the primate musculoskeletal system.

The positional behavior of pygmy marmosets (Cebuella pygmaea) in northwestern Bolivia

Pygmy marmosets are distinctive given their diminutive body size, their year-round reliance upon exudates, and their use of morphologically adapted tegulae to engage in a high degree of claw-clinging behaviors associated with exudate exploitation. This project examined the positional behavior and habitat preferences of one group of pygmy marmosets in a secondary forest within the Department of Pando, northwestern Bolivia. Results from this study indicate that pygmy marmosets primarily use claw-clinging during feeding (89.6%) with preferential use of large vertical trunks. Claw-clinging was also the dominant postural mode during exudate foraging (43.1%) with preferential use of large vertical trunks. Quadrupedalism was the dominant locomotor mode during travel (55.7%) with preferential use of bamboo and medium-sized substrates. These results support previous notions that claw-climbing is a solution to overcome the constraints of small body size while suggesting that quadrupedalism is a habitat-dependent locomotor mode.

Adaptive Body Posture Analysis Using Collaborative Multi-Sensors for Elderly Falling Detection

Multisensors explore the collaborative analysis of body posture modes to detect accidental-falling incidents and provide relevant data to medical personnel for rescue and treatment.

La Dynamique Posturale Non-Linéaire. Partie I : bases et fondements

The different sensorial systems involved in the postural control form a super system preserving the static and dynamical equilibrium of a standing human being, motionless or moving. Now, the human posture captors are endowed with conditions that are sufficient to constitute a dynamical system. Then, we can show that: (i) generic properties of dynamical systems may be applied to the postural system, (ii) we may benefit from conceptual justifications to postural interactions experienced at a clinical level. Moreover, concerning the issue of the multi-causal chain in posturology, it is possible to infer and characterize a certain number of generic properties relative to these postural interactions. From this theoretical grounding, based on the knowledge of dynamical systems, it appears licit to introduce the concept of Non-linear Postural Dynamics (NPD). In a first part of this paper, the bases and foundations of NPD are presented, while the second part deals with different possible modes of NPD. Indeed, because the postural system is comparable to the structure of a dynamical system, it turns out that the former, natural seat of non-linear interaction dynamics, exhibits four dynamical modes and only four, « solutions » to the whole postural system. These four modes are as follows: (1) the quasi-linear mode, (2) the stationary mode, (3) the non-linear convergent mode, and (4) the chaotic mode. The present paper is devoted to the definition and articulation of these postural dynamic's modes. A codification of the clinical elements of their recognition should constitute a logically indispensable sequel. However, by their very constitutive principles themselves, some of these modes call for a functional multi-disciplinary approach. As a consequence, in the search for therapeutic protocols, not blindly but rather built on the interplay of various medical fields relative to posture and its physio-dynamical equilibrium, it is necessary to identify in a first step, and as surely as possible, the postural mode in which the patient stands.