Natural Locomotion Research Articles

The Histamine H3 Receptor Antagonist DL77 Ameliorates MK801-Induced Memory Deficits in Rats.

The role of Histamine H3 receptors (H3Rs) in memory, and the prospective of H3R antagonists in pharmacological control of neurodegenerative disorders, e.g., Alzheimer disease (AD) is well-accepted. For that reason, the procognitive effects of the H3R antagonist DL77 on cognitive impairments induced with MK801 were tested in an inhibitory passive avoidance paradigm (PAP) and novel object recognition (NOR) task in adult male rats, using donepezil (DOZ) as a standard drug. Acute systemic pretreatment with DL77 (2.5, 5, and 10 mg/kg, i.p.) significantly ameliorated memory deficits induced with MK801 in PAP (all P < 0.05, n = 7). The ameliorative effect of most promising dose of DL77 (5 mg/kg, i.p.) was reversed when rats were co-injected with the H3R agonist R-(α)-methylhistamine (RAMH, 10 mg/kg, i.p.) (p = 0.701 for MK801-amnesic group vs. MK801+DL77+RAMH group, n = 6). In the NOR paradigm, DL77 (5 mg/kg, i.p.) counteracted long-term memory (LTM) deficits induced with MK801 (P < 0.05, n = 6–8), and the DL77-provided effect was similar to that of DOZ (p = 0.788, n = 6–8), and was reversed when rats were co-injected with RAMH (10 mg/kg, i.p.) (p = 0.877, n = 6, as compared to the (MK801)-amnesic group). However, DL77 (5 mg/kg, i.p.) did not alter short-term memory (STM) impairment in NOR test (p = 0.772, n = 6–8, as compared to (MK801)-amnesic group). Moreover, DL77 (5 mg/kg) failed to modify anxiety and locomotor behaviors of animals innate to elevated-plus maze (EPM) (p = 0.67 for percentage of time spent exploring the open arms, p = 0.52 for number of entries into the open arms, p = 0.76 for percentage of entries into the open arms, and p = 0.73 number of closed arm entries as compared to saline-treated groups, all n = 6), demonstrating that the procognitive effects observed in PAP or NOR tests were unconnected to alterations in emotions or in natural locomotion of tested animals. These results signify the potential involvement of H3Rs in modulating neurotransmitters related to neurodegenerative disorders, e.g., AD.

A NATUREZA DA FORÇA: NOTAS SOBRE O TEXTO LATINO DE IN PHYSICA II, 1, L. 11-14 DE FILOPONO

Este artigo apresenta uma exegese do In Physica II, 1, l. 11-14 de Filipono, texto no qual o autor expõe uma compreensão da noção de força como formadora e diretiva da totalidade dos corpos na medida em que os mantém no ser, conferindo, portanto, unidade e ordenação ao cosmo. Nesse contexto, é possível sustentar que a força vinculada com a locomoção natural dos corpos simples tomados em conjunto, o cosmo, é uma anima mundi. Para tanto, a noção de vida, também presente no In Physica II, 1, l. 11-14, é tomada como chave de leitura, uma vez que por ela tem sentido afirmar que o cosmos possui uma forma, esta que, no limite, é a própria alma do cosmo.

A load-based mechanism for inter-leg coordination in insects.

Animals rely on an adaptive coordination of legs during walking. However, which specific mechanisms underlie coordination during natural locomotion remains largely unknown. One hypothesis is that legs can be coordinated mechanically based on a transfer of body load from one leg to another. To test this hypothesis, we simultaneously recorded leg kinematics, ground reaction forces and muscle activity in freely walking stick insects (Carausius morosus). Based on torque calculations, we show that load sensors (campaniform sensilla) at the proximal leg joints are well suited to encode the unloading of the leg in individual steps. The unloading coincides with a switch from stance to swing muscle activity, consistent with a load reflex promoting the stance-to-swing transition. Moreover, a mechanical simulation reveals that the unloading can be ascribed to the loading of a specific neighbouring leg, making it exploitable for inter-leg coordination. We propose that mechanically mediated load-based coordination is used across insects analogously to mammals.

Propulsion via flexible flapping in granular media.

Biological locomotion in nature is often achieved by the interaction between a flexible body and its surrounding medium. The interaction of a flexible body with granular media is less understood compared with viscous fluids partially due to its complex rheological properties. In this work, we explore the effect of flexibility on granular propulsion by considering a simple mechanical model in which a rigid rod is connected to a torsional spring that is under a displacement actuation using a granular resistive force theory. Through a combined numerical and asymptotic investigation, we characterize the propulsive dynamics of such a flexible flapper in relation to the actuation amplitude and spring stiffness, and we compare these dynamics with those observed in a viscous fluid. In addition, we demonstrate that the maximum possible propulsive force can be obtained in the steady propulsion limit with a finite spring stiffness and large actuation amplitude. These results may apply to the development of synthetic locomotive systems that exploit flexibility to move through complex terrestrial media.

A multidirectional gravity-assist algorithm that enhances locomotor control in patients with stroke or spinal cord injury

Gait recovery after neurological disorders requires remastering the interplay between body mechanics and gravitational forces. Despite the importance of gravity-dependent gait interactions and active participation for promoting this learning, these essential components of gait rehabilitation have received comparatively little attention. To address these issues, we developed an adaptive algorithm that personalizes multidirectional forces applied to the trunk based on patient-specific motor deficits. Implementation of this algorithm in a robotic interface reestablished gait dynamics during highly participative locomotion within a large and safe environment. This multidirectional gravity-assist enabled natural walking in nonambulatory individuals with spinal cord injury or stroke and enhanced skilled locomotor control in the less-impaired subjects. A 1-hour training session with multidirectional gravity-assist improved locomotor performance tested without robotic assistance immediately after training, whereas walking the same distance on a treadmill did not ameliorate gait. These results highlight the importance of precise trunk support to deliver gait rehabilitation protocols and establish a practical framework to apply these concepts in clinical routine.

Comparing Femur Cross‐sectional Morphology in Young Outbred Mice Following Daily Exposure to Muscle‐, Impact‐, or Combined Loading of the Hind Limb Skeleton

Limb bones are exposed to a multitude of intrinsic and extrinsic loading forces which they must resist in order to prevent fracture and maintain function. Bone is a plastic tissue which can adapt to encountered loads by increasing cortical thickness in areas of high strain and resorbing cortex in areas of low strain, thereby optimizing strength, weight, and metabolic requirements. While exercises such as running and jumping are known to induce changes in the cross‐sectional dimensions of limb bones, the relative contributions of muscular contractions and extrinsic ground reaction forces (GRF) in altering bone morphology are not fully understood. We compared femur gross and cross‐sectional morphology in mice exposed to four loading environments that differ in the source of forces imposed on the skeleton: swimming (muscle‐dominated), impact loading via falling (GRF‐dominated), running (combined muscle and GRF characteristic of natural locomotion), and sedentary controls. Four‐week‐old male Hsd:ICR mice were randomly assigned to treatment groups and completed loading exercises daily for 20 days. Mice were injected twice with fluorochrome labels during the final week of treatment to allow measurement of mineral apposition rates and regionalization. Undecalcified femoral mid‐diaphyseal sections were photographed using light and fluorescent microscopy and analyzed for cross‐sectional properties and mineral apposition patterns. We found that the falling impact group had the greatest distal femoral width, but the swim group had the greatest width at the mid‐diaphysis. The jump impact group demonstrated significantly greater cross‐sectional area and moments of inertia than controls, indicating increased resistance to torsion and bending compared to other loading regimes. Examination of mineral apposition patterns showed that mineral apposition was greatest posterolaterally in all groups, with additional medial or posterior cortical drift characterizing each loading treatment. These results indicate regional sensitivity of the growth and morphology of the femur to muscle‐ and GRF‐derived loads and suggest that impact loading induces the growth of stronger bones than other forms of exercise. Future analyses will use 3D geometric morphometrics to examine overall shape differences in femur, tibia, and pelvis following loading treatment.Support or Funding InformationUniversity of Missouri School of Medicine

Recapturing the canopy: stimulating Bornean orang-utan (Pongo pygmaeus) natural locomotion behaviour in a zoo environment

Orang-utans are the largest mainly arboreal animal: wild orang-utans rarely come to the forest floor. In contrast, the locomotion behaviour of captive orang-utans encompasses more time on the ground and they spend less time on locomotion than their wild conspecifics. Moreover, their most frequently employed climbing postures differ from those of wild orang-utans. More natural locomotion behaviour may be stimulated by the design of appropriate enclosures. This study aimed to investigate how the design of orang-utan enclosures influences locomotion behaviour both quantitatively (i.e. time spent above ground and on locomotion) and qualitatively (i.e. types of movement). We collected continuous focal samples from 11 captive Bornean orang-utans ( Pongo pygmaeus ) at Apenheul Primate Park (Apeldoorn, The Netherlands). During the study, Apenheul offered two types of outdoor enclosures to their orang-utans: horizontal trunk enclosures with a relatively high number of large-diameter, horizontal tree trunks; and multiple rope enclosures with a relatively high number of small-diameter ropes. The results showed that the orang-utans’ quantitative locomotion behaviour was more natural in the horizontal trunk than in the multiple rope enclosures: they spent less time on the ground and more time on above-ground locomotion. However, the orang-utans’ qualitative locomotion behaviour seemed more natural in the multiple rope enclosures than in the horizontal trunk enclosures. This indicates that both horizontal trunks and small-diameter substrates are required to stimulate natural quantitative and qualitative locomotion behaviour. Zoos can apply our recommendations to stimulate natural locomotion behaviour in captive orang-utans, which may improve their physical condition and thereby increase their wellbeing.

PHYSICAL EDUCATION FORMATION WITH IN BORDERS OF MODERN UKRAINE IN THE MIDDL E AGES

The article is dedicated to the investigation of physical education formation in Kievan Rus. The work outlines the worldview aspects of body-building, reveals the essence of healthy lifestyle in written documents of the IX–XIV centuries. Different means (folk games, dances, entertainments, fist fights, wrestling, exercises with objects, exercises using means of movement, natural locomotion) and forms (folk, religious, educational, military-physical, competitive) of physical education in Kievan Rus are presented in the article. Based on the analysis of scientific literature, ancient chronicles, ethnographic records, archaeological finds, folklore materials and own research results, we defined the fallowing peculiarities of the functioning of physical education in Kievan Rus: the connection of physical education with the outlook, way of life and place of people residence; interpenetration of inter-ethnic elements of physical education; interconnection of festive-gaming activity and military physical training; gradual transition to organized forms of physical education. In the literary documents of the IX–XIV centuries of the Kievan Rus the issue of healthy lifestyle was described. It ensured the training of young people in labor and military activities. «Pouchenia» by Volodymyr Monomakh provides a universal system for the education of young people, which includes productive labor activity, mental health, motor activity, hardening, rational nutrition, and personal hygiene. Means of physical education in Kievan Rus are divided into three main groups: physical exercises, natural forces, and hygiene factors. Physical exercises were divided into subgroups, depending on the specifics of motor activity: folk games, dancing and entertainment, fist fights and fighting, exercises with objects, exercises using means of movement. The forms of physical education in Kyivan Rus were formed due to the outlook, customs and way of life of the population. The results of the study made it possible to determine the following forms: folk, religious, educational, adventure, military-physical preparation.

Engagement of the Rat Hindlimb Motor Cortex across Natural Locomotor Behaviors.

We mapped the neuronal population responses in the hindlimb motor cortex to hindlimb kinematics and hindlimb muscle synergies across a spectrum of natural locomotion behaviors. Robust task-specific neuronal population responses revealed that the rat motor cortex displays similar modulation as other mammals during locomotion. However, the reduced motor cortex activity during more automated behaviors suggests a relationship between the degree of engagement and task complexity. This relationship emphasizes the importance of the behavioral procedure to engage the motor cortex during motor control studies, gait rehabilitation, and locomotor neuroprosthetic developments in rats.

Are interlimb interactions disturbed in patients with Parkinson’s disease? A study under unloading conditions

During natural human locomotion neural connections characteristic for the control of quadrupedal walking are activated. The degree of interaction between the neural networks generating rhythmic movements of the upper and lower extremities, depends on the tonic state of each of these networks, adjustable by motor command in the brain. The distortion of such command in patients with Parkinson's disease (PD) may lead to disturbance of interlimb interactions. In conditions of arms and legs unloading in 17 patients with PD and 16 healthy subjects investigated the effect of limb movement of one girdle on the parameters of motor activity of the limbs of the other girdle in their combined cyclic movements. In patients the weakening of influences of active or passive arm movements, and active movements of the distal parts of the arms on voluntary leg movements was shown, while in healthy subjects the effect of arm movements on the parameters of voluntary movements was significant. The effect of arm movements on the possibility of involuntary activation of air- stepping by vibratory stimulation of the leg muscles in patients was absent, while in healthy subjects the motor activity of the arms increased the opportunity of involuntary rhythm activation. The differences in the influence of leg movements to the rhythmic movement of the upper extremities in patients and healthy subjects were revealed. The medication exhibited interlimb interaction, but it was insufficient for normalization of the state of neural networks in patients. It is concluded that in patients with PD, neural networks generating stepping rhythm are in a state of heightened tonic activity. This does not allow not only activating involuntary rhythmic movements, but also showing facilitation effect with arms to legs.

Restoring walking after total knee arthroplasty: Symmetries of 3D body centre of mass trajectory and mechanical work

INTRODUCTION Osteoarthritis (OA) is a degenerative joint disease constantly increasing in elderly population and the knee is one of the most affected joints. It contributed together with other musculoskeletal disorders to the 2nd greatest cause of disability in the WHO Global Burden of Disease [1] and patients no more responding to conservative treatments undergo total knee-arthroplasty (TKA) to remove pain and permit an asymptomatic walking. Radiological reports and questionnaires are the current diagnostic tools employed both for the diagnosis and monitoring of OA progression. However, substantial discordance exists between current diagnostic outcomes using those tools and OA symptoms [2]. Further investigation need to identify more reliable biomarkers for early detection of the disease, correct timing for TKA and post-surgery monitoring. Therefore in this study we aim to describe quantitatively the gait of OA patients undergoing to the TKA, with a specific focus on the 3D body centre of mass (BcOM) trajectory (Locomotion 3D Lissajous Countours [3]). METHODS 7 patients with unilateral knee OA (68.9 ± 4.8 years, 69.1 ± 9.1 kg, 1.60 ± 0.07 m) were tested for 4 times: before surgery (PRE), after 2 months (POST2), after 6 months (POST6) and after 12 months (POST12) from TKA. Each time patients were asked to i) complete a WOMAC questionnaire, ii) walk on a 5-force plates (Bertec, Columbus, OH, U.S.A) corridor to estimate spontaneous velocity (vs), and iii) walk for 1 min on a treadmill at 3 selected velocities (vs, v1 and v2). Two velocities, lower than vs, were calculated starting from the Froude Number (Fr): v1 = -30% Fr and v2 = -15% Fr, respectively). A 18 marker model was used to calculate (VICON, Oxford UK) the 3D BCoM trajectory, its symmetries, stride frequency (SF), double contact (DC) time, right and left duty factor, mechanical external and internal work (Wext and Wint respectively), total work (Wtot) and energy recovery (RE). RESULTS WOMAC indices improved significantly already after 6 months and vs significantly increased from 0.89 ± 0.14 (PRE) to 1.13 ± 0.07 m/s (POST12). The figure shows the average BCoM profiles during walking (pointed arrows refer to vertical (z) and progression (x) axes), where upper boundary reaches a higher vertical position (3%) in the POST12 condition compared to the PRE condition and a more symmetrical shape, significantly in x and z directions. For the same walking speed SF decreased significantly already after two months from TKA, DC time decreased to 20% of the stride length and duty factor also assumed lower values after surgery. Patients after TKA improved their locomotor energy recovery mechanisms, reducing mechanical external work by 10%. WINT was constant along the months, while RE slightly increased after TKA. DISCUSSION The group of quantitatively analysed variables, suggest as patients with prosthesis tend to re-establish their natural locomotion pattern after TKA. Body centre of mass analysis during walking, including symmetry and mechanical energy evaluations, quantitatively assess osteoarthritis disease level and can be employed to monitor patients before and after pharmacological and surgical interventions. The same methodology could be applicable to neurological pathologies and to patients affected by other orthopaedic pathologies affecting other limb joints, like hip or ankle. The effects of different prosthesis or surgical techniques on a single pathology/joint could be equally investigated.

Feasibility of a walking virtual reality system for rehabilitation: objective and subjective parameters.

BackgroundEven though virtual reality (VR) is increasingly used in rehabilitation, the implementation of walking navigation in VR still poses a technological challenge for current motion tracking systems. Different metaphors simulate locomotion without involving real gait kinematics, which can affect presence, orientation, spatial memory and cognition, and even performance. All these factors can dissuade their use in rehabilitation. We hypothesize that a marker-based head tracking solution would allow walking in VR with high sense of presence and without causing sickness. The objectives of this study were to determine the accuracy, the jitter, and the lag of the tracking system and its elicited sickness and presence in comparison of a CAVE system.MethodsThe accuracy and the jitter around the working area at three different heights and the lag of the head tracking system were analyzed. In addition, 47 healthy subjects completed a search task that involved navigation in the walking VR system and in the CAVE system. Navigation was enabled by natural locomotion in the walking VR system and through a specific device in the CAVE system. An HMD was used as display in the walking VR system. After interacting with each system, subjects rated their sickness in a seven-point scale and their presence in the Slater-Usoh-Steed Questionnaire and a modified version of the Presence Questionnaire.ResultsBetter performance was registered at higher heights, where accuracy was less than 0.6 cm and the jitter was about 6 mm. The lag of the system was 120 ms. Participants reported that both systems caused similar low levels of sickness (about 2.4 over 7). However, ratings showed that the walking VR system elicited higher sense of presence than the CAVE system in both the Slater-Usoh-Steed Questionnaire (17.6 ± 0.3 vs 14.6 ± 0.6 over 21, respectively) and the modified Presence Questionnaire (107.4 ± 2.0 vs 93.5 ± 3.2 over 147, respectively).ConclusionsThe marker-based solution provided accurate, robust, and fast head tracking to allow navigation in the VR system by walking without causing relevant sickness and promoting higher sense of presence than CAVE systems, thus enabling natural walking in full-scale environments, which can enhance the ecological validity of VR-based rehabilitation applications.

The Manifestation of the Discrete and Continuous Types of Bioelectric Control of Natural Locomotion at the Over-Five Age

The concept of physiology of activity by N.A. Bernstein, developed on the grounds of in-depth theoretical and empirical analysis of natural human locomotion, served as a basis for understanding the target determination of human behavior, the mechanisms of motor skills formation and levels of building movements. Scientific and technological progress has determined the emergence of new methods for registration of natural human locomotion parameters, complementing Bernstein’s concept with new structures. The method of interference surface electromyogram based on the "Neuro-MEP" computer system of the Neurosoft Company (Ivanovo, Russia) was used to study the indicators of signal implementation amplitude and frequency, as well as electromyogram patterns of shank, thigh and back muscles during squatting by 5-6-year-old children. The dominant types of patterns were determined. It has been found that in the study of muscle groups, the electromyogram burst waveform dominates at the age of 5 years and the monophasic waveform dominates at the age of 6 years. Based on the analysis of the content of obtained electromyograms, we justified the discrete and continuous type of bioelectric control. The discrete type dominates at the age of 5 years. The main criterion of its manifestation is the record of the EMG burst waveform. The continuous type of bioelectric control dominates at the age of 6 against the EMG monophasic waveform recording. It has been revealed that formation of the established types of bioelectric control of the muscle groups under study is subject to the laws of heterochrony and heterotrophy.

Reductions in Cardiovascular and Metabolic Demands During Work Rate Matched Eccentric Stepping Exercise

Eccentric (ECC) exercise training induces greater increases in muscle strength, hypertrophy and performance compared with work rate (WR) matched concentric (CON) exercise. During ECC WR-matched cycle ergometry there is also a reduction in cardiovascular (CV) and metabolic demands compared with CON. However, the magnitude of this reduction during ECC exercise, which more closely mirrors natural locomotion, is unknown. Similarly, it is unknown whether ECC stepping exercise performed at the same CON metabolic rate can be tolerated to allow a greater volume of work to be accumulated for the same CV and metabolic demand. PURPOSE: To compare CV and metabolic responses during CON and ECC stepping exercise performed at the same mechanical and metabolic rates. METHODS: Eight participants (5 m, 3 f), (mean ± SD: 22 ± 2 yr; 172 ± 6 cm; 70 ± 9 kg) performed a CON and ECC ramp incremental test to the limit of tolerance on a step ergometer (Eccentron; BTE, Hanover, MD, USA). CON and ECC constant WR tests were then performed for 15 min at the same mechanical (work) and metabolic (pulmonary oxygen uptake (VO2)) rate, set at 90% of the CON lactate threshold (i.e. moderate-intensity). All tests were undertaken > 48 hours apart. Breath-by-breath VO2, heart rate (HR), and blood pressure (BP) responses were measured throughout. RESULTS: During constant exercise at the same mechanical WR (36.2 ± 6.2 W), in which a steady-state was attained, compared with CON, ECC [INCREMENT]VO2 was 64 ± 9 % lower (22 ± 0.07 vs. 0.62 ± 0.17 l.min-1; P < 0.05), [INCREMENT]HR was 51 ± 13 % lower (14.6 ± 5.9 vs. 29.9 ± 7.2 beats.min-1; P < 0.05) and [INCREMENT] mean arterial pressure was 56 ± 18 % lower (7 ± 3 vs. 16 ± 5 mmHg; P < 0.05). The ECC WR predicted to match for metabolic rate (VO2, 1.2 ± 0.1 l•min-1) was 66 ± 19 % higher (60.0 ± 13.2 vs. 36.2 ± 6.2 W; P < 0.001), and allowed a greater volume of work to be accumulated; however, VO2 and HR continued to increase throughout the exercise. CONCLUSION: ECC stepping exercise at the same mechanical WR reduces the CV and metabolic demand of the exercise. Although ECC exercise at the same predicted VO2 was tolerable, and allowed a greater volume of work to be accumulated, VO2 and HR increased throughout the exercise, suggesting this was performed at a higher exercise intensity, which may be contraindicated in some populations.

Propulsion for Biological Inspired Micro-Air Vehicles (MAVs)

Small Unmanned Aerial Vehicles have been receiving an increasingly interest in the last decades, fostered by the need of vehicles able to perform surveillance, communications relay links, ship decoys, and detection of biological, chemical, or nuclear materials. Smaller and handy vehicles Micro Air vehicles (MAVs) become even more challenging when DARPA launched in 1997 a pilot study into the design of portable (150 mm) flying vehicles to operate in D3—dull, dirty and dangerous—environments. More recently DARPA launched a Nano Air Vehicle (NAV) program with the objective of developing and demonstrating small (<100 mm; <10 g) lightweight air vehicles with the potential to perform indoor and outdoor missions. The current investigation is focused on the mechanisms involved with natural locomotion (propulsion and lift should not be considered independently). Biological systems with interesting applications to MAVs are generally inspired on flying insects or birds; however, similarly to the aerodynamics of flight, powered swimming requires animals to overcome drag by producing thrust. Commonalities between natural flying and swimming are analyzed together with flow control issues as a purpose of improvement on biology-inspired or biomimetic concepts for Micro Air Vehicles implementation.

Adaptive Torque and Position Control for a Legged Robot Based on a Series Elastic Actuator

Inspired by biological systems, we seek to achieve natural dynamics and versatile locomotion for hopping or running robots by installing a series elastic actuator (SEA) in the joints due to its compliant property, passive adaptability and energy storage. However, robots equipped with these actuators have drawbacks in terms of substantial delay and limited bandwidth in their position control, especially when a robot has to choose its foothold while it is running at a demanding speed. To solve these problems, compliance control and adaptive position/torque control are introduced to a hopping- legged robot in this paper. The compliant performance of the robot can be improved through the intrinsic property of an SEA with a torque control algorithm. Combining the kinetics model and stochastic model of a 2-DOF robot, an adaptive position control with Kalman Filtering (KF) is developed to provide rapid convergent state estimation of the load on the robotic end-effector by solving the inverse dynamics. Validating the robustness and effectiveness of the proposed algorithm on our hopping-legged robot Tigger, the experimental results show very good position-tracking and disturbance-rejection, as well as flexible interactions while operating in a complex environment.

Hybrid Motion Graphs for Character Animation

Many works in the literature have improved the performance of motion graphs for synthesis the humanlike results in limited domains that necessity few constraints like dance, navigation in small game like environments or in games by the gesture of feedback on a snowboard tutorial. The humanlike cannot exist in an environment without interacting with the world surrounding them; the naturalness of the entire motion extremely depends on the animation of the walking character, the chosen path and the interaction motions. Addressing exact position of end-effectors is the main disadvantage of motion graphs which cause less importance expended to the search for motions with no collision in complex environments or manipulating motions. This fact motivates this approach which is the proposition of an hybrid motion graphs taking advantages of motion graphs to synthesis a natural locomotion and overcoming their limitations in synthesis manipulation motions by combined it with an inverse kinematic method for synthesis the upper-body motions.

Influence of Lateral Dominance of Sight on the Quality of the Natural Locomotion Performance at the Senior Preschool Age

Influence of Lateral Dominance of Sight on the Quality of the Natural Locomotion Performance at the Senior Preschool Age

Natural Locomotion Based on Foot-Mounted Inertial Sensors in a Wireless Virtual Reality System

Virtual reality has become a promising field in recent decades, and its potential now seems clearer than ever. With the development of handheld devices and wireless technologies, interest in virtual reality is also increasing. Therefore, there is an accompanying interest in inertial sensors, which can provide such advantages as small size and low cost. Such sensors can also operate wirelessly and be used in an increasing number of interactive applications. An example related to virtual reality is the ability to move naturally through virtual environments. This is the objective of the real-walking navigation technique, for which a number of advantages have previously been reported in terms of presence, object searching, and collision, among other concerns. In this article, we address the use of foot-mounted inertial sensors to achieve real-walking navigation in a wireless virtual reality system. First, an overall description of the problem is presented. Then, specific difficulties are identified, and a corresponding technique is proposed to overcome each: tracking of foot movements; determination of the user’s position; percentage estimation of the gait cycle, including oscillating movements of the head; stabilization of the velocity of the point of view; and synchronization of head and body yaw angles. Finally, a preliminary evaluation of the system is conducted in which data and comments from participants were collected.

Representation of impossible worlds in the cognitive map.

It is often assumed that humans represent large-scale spatial environments as cognitive maps, but the exact features of these representations are still unclear. We investigate the structure of this representation with the impossible worlds paradigm by testing whether the information provided by virtual environments (VEs) with arbitrary violations of geometrical rules is rectified ("distorted") to become compatible with a map-like structure. The experiments were conducted in virtual reality using a natural locomotion interface. The subjects' task was to explore possible and impossible VEs carefully to achieve a "full understanding". After each trial, they had to "blindly" reproduce the path through the environment from memory in a VE with impoverished visual cues. We have found no evidence for angular or configurational distortions or alterations in the blind reproductions of impossible VEs. Blind reproduction indicates that impossible VEs do not require a transformation into a "possible" format to make them fit into the cognitive map. This suggests that the representation may not be similar to a map in a bounded sense of interpretation but requires more generalized concepts for its understanding.