Avian gait analysis

Modern broilers have difficulty walking, and there is ongoing debate as to whether the birds are in pain. Most gait analysis of poultry consists of visual assessment and scoring, and the results are therefore very subjective. In order to describe and quantify gait patterns accurately, a more objective method is required. Only then can differences between the gait of normal chickens and modem broilers be properly described, and attempts made to determine whether the observed gait patterns are the result of the conformation of the birds, or the presence of pain.Two methods were used in this research. The pedobarograph is a relatively novel method of gait analysis for animals which enables footfall patterns to be recorded, enabling spatial parameters (step length, width and angle) and plantar pressure patterns to be described and measured. A Kistler force plate was then used to measure the three - dimensional ground reaction forces (GRF's) produced during walking. Speed and cadence can be calculated using either system.Gait patterns are described for normal birds, and for different strains of broilers, raised on different feeding regimes. All the gait parameters were very variable, both between birds, and within the same bird, even when bodyweight and speed were controlled for. Despite the high variability, however, significant differences were identified in many of the gait parameters between the different groups.The vertical and craniocaudal GRF's of Brown Leghorns showed similar characteristics to those produced in human walking. The peak vertical forces were of a similar order of magnitude in the birds as in humans (125 -150 % bodyweight), and the peak craniocaudal forces, and rate of change of force, were closely tied to speed. All the GRF's in the birds increased significantly with increasing speed, except for braking rate (which was more variable) and stance time (which decreased significantly). The mediolateral forces were much greater in the birds than have been reported for other species, however, with peaks of 10 -22% bodyweight. Analysis of plantar pressures showed that the pressures were concentrated on the digital pads, with the lowest pressures on the metatarsal pad ( <131 kNm "2), and highest pressures on the medial toe (up to 218 kNm "2).Combined gait analysis and morphometric studies of ad libitum -fed selected broilers identified many ways in which their gait deviated from that of relaxed broilers and Brown Leghorns, in ways which would serve to increase stability and decrease stresses on the skeleton. The ad libitum -fed selected birds (compared to restricted -fed strain -mates and relaxed birds of the same weight), had more breast muscle anteriorly, and shorter, wider legs, but with immature bones, of lower % ash content. They moved more slowly, taking short steps, and positioned their feet wide apart and turned `toe -out' to increase their walking base. They kept their feet on the ground for longer, with short swing periods, and long double contact times. Decreasing the unstable periods of single support, and increasing the stance periods, reduces the peak forces on the skeleton. The slow speed and short steps also reduce the vertical excursions of the centre of gravity. The very wide walking base results in abnormally large mediolateral forces being required to move the centre of gravity over the stance leg, however, increasing the inefficiency of the gait, leading to fatigue. Mediolateral forces in ad libitum -fed selected birds averaged 17 -21% bodyweight at 6 weeks, compared to 10 -11% in the Brown Leghorns, and <5 -8% in humans (Biewener, 1992).Changes in the GRF's were also demonstrated in the slower growing (restricted -fed) broilers with age. In these birds, both the peak vertical forces and the peak mediolateral forces decreased with age, despite the fact that the birds increased in size (and girth) and their speed of movement remained similar. This indicates that the birds developed gait optimisations as they grew (as is the case with children), possibly because the slower growth allowed the body to develop more in proportion.Analysis of the gait of a small number of lame birds demonstrated marked differences in the spatial and force parameters between the sound and lame limb. The peak forces on the lame leg were dramatically reduced, and compensatory increases were seen in the GRF's of the sound limb. The birds used several methods to avoid fully loading the lame leg: flapping the wings to raise the centre of gravity, pushing up on the sound limb prior to placing the lame leg down, and flexing the lame limb as it starts to weightbear.There were no changes in the GRF's or temporal parameters of gait of broilers given analgesic (carprofen). Unfortunately, this does not prove conclusively that the birds were not in pain, as analgesic efficacy has not been validated in broilers, and it is also possible that the parameters under test do not change in the presence of pain. However the incidental finding of old blood in synovial fluid samples of over 50% of the ad libitum -fed broilers adds to the welfare concerns. A second interesting finding was the high alkalinity of the fluid (median pH 8.15 - 8.40), with the possible consequences on intra- articular pharmacodynamics. Although the analgesic study proved inconclusive, results of the gait and morphometric studies demonstrate that it is possible to explain the gait patterns of ad libitum -fed selected broilers based on their body conformation alone

First Person Perspective of Seated Participants Over a Walking Virtual Body Leads to Illusory Agency Over the Walking

Agency, the attribution of authorship to an action of our body, requires the intention to carry out the action, and subsequently a match between its predicted and actual sensory consequences. However, illusory agency can be generated through priming of the action together with perception of bodily action, even when there has been no actual corresponding action. Here we show that participants can have the illusion of agency over the walking of a virtual body even though in reality they are seated and only allowed head movements. The experiment (n = 28) had two factors: Perspective (1PP or 3PP) and Head Sway (Sway or NoSway). Participants in 1PP saw a life-sized virtual body spatially coincident with their own from a first person perspective, or the virtual body from third person perspective (3PP). In the Sway condition the viewpoint included a walking animation, but not in NoSway. The results show strong illusions of body ownership, agency and walking, in the 1PP compared to the 3PP condition, and an enhanced level of arousal while the walking was up a virtual hill. Sway reduced the level of agency. We conclude with a discussion of the results in the light of current theories of agency

First person perspective of seated participants over a walking virtual body leads to illusory agency over the walking

Agency, the attribution of authorship to an action of our body, requires the intention to carry out the action, and subsequently a match between its predicted and actual sensory consequences. However, illusory agency can be generated through priming of the action together with perception of bodily action, even when there has been no actual corresponding action. Here we show that participants can have the illusion of agency over the walking of a virtual body even though in reality they are seated and only allowed head movements. The experiment (n = 28) had two factors: Perspective (1PP or 3PP) and Head Sway (Sway or NoSway). Participants in 1PP saw a life-sized virtual body spatially coincident with their own from a first person perspective, or the virtual body from third person perspective (3PP). In the Sway condition the viewpoint included a walking animation, but not in NoSway. The results show strong illusions of body ownership, agency and walking, in the 1PP compared to the 3PP condition, and an enhanced level of arousal while the walking was up a virtual hill. Sway reduced the level of agency. We conclude with a discussion of the results in the light of current theories of agency

Physics-based control of virtual characters in low frequency simulations

International audienceUsing a lower simulation frequency for physics-based control of virtual characters frees computation time that can be used for more complex environment. However, using low simulation frequency may introduce instabilities inside the simulation. In this paper, we demonstrate that even a simple control strategy can be used at a low simulation frequency by adapting the control parameters. Indeed we show that lower frequencies hold a more restrictive space of possible control parameters than higher ones. We propose a method to find optimized control parameters for frequencies as low as 200Hz. As using such low frequencies may introduce foot-ground contact instabilities, we also introduce an additional control feedback on the stance leg. Our controller shows similar robustness as high frequency controller while using 0.8ms per simulation step

Virtuality Supports Reality for e-Health Applications

Strictly speaking the word “virtuality” or the expression “virtual reality” refers to an application for things simulated or created by the computer, which not really exist. More and more often such things are becoming equally referred with the adjective “virtual” or “digital” or mentioned with the prefixes “e-” or “cyber-”. So we know, for instance, of virtual or digital or e- or cyber- community, cash, business, greetings, books .. till even pets. The virtuality offers interesting advantages with respect to the “simple” reality, since it can reproduce, augment and even overcome the reality. The reproduction is not intended as it has been so far that a camera films a scenario from a fixed point of view and a player shows it, but today it is possible to reproduce the scene dynamically moving the point of view in practically any directions, and “real” becomes “realistic”. The virtuality can augment the reality in the sense that graphics are pulled out from a television screen (or computer/laptop/palm display) and integrated with the real world environments. In this way useful, and often in somehow essentials, information are added for the user. As an example new apps are now available even for iphone users who can obtain graphical information overlapped on camera played real scene surroundings, so directly reading the height of mountains, names of streets, lined up of satellites .., directly over the real mountains, the real streets, the real sky. But the virtuality can even overcome reality, since it can produce and make visible the hidden or inaccessible or old reality and even provide an alternative not real world. So we can virtually see deeply into the matter till atomic dimensions, realize a virtual tour in a past century or give visibility to hypothetical lands otherwise difficult or impossible to simple describe. These are the fundamental reasons for a naturally growing interest in “producing” virtuality. So here we will discuss about some of the different available methods to “produce” virtuality, in particular pointing out some steps necessary for “crossing” reality “towards” virtuality. But between these two parallel worlds, as the “real” and the “virtual” ones are, interactions can exist and this can lead to some further advantages. We will treat about the “production” and the “interaction” with the aim to focus the attention on how the virtuality can be applied in biomedical fields, since it has been demonstrated that virtual reality can furnish important and relevant benefits in e-health applications. As an example virtual tomography joins together 3D imaging anatomical features from several CT (Computerized axial Tomography) or MRI (Magnetic Resonance Imaging) images overlapped with a computer-generated kinesthetic interface so to obtain a useful tool in diagnosis and healing. With the new endovascular simulation possibilities, a head mounted display superimposes 3D images on the patient’s skin so to furnish a direction for implantable devices inside blood vessels. Among all, we chose to investigate the fields where we believe the virtual applications can furnish the meaningful advantages, i.e. in surgery simulation, in cognitive and neurological rehabilitation, in postural and motor training, in brain computer interface. We will furnish to the reader a necessary partial but at the same time fundamental view on what the virtual reality can do to improve possible medical treatment and so, at the end, resulting a better quality of our life

Human locomotion and energetics in simulated partial gravity

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1992.Includes bibliographical references (leaves 214-219).by Dava Jean Newman.Ph.D

Altering gait symmetry using an asymmetric visual cue

Gait asymmetries are a common problem for clinical populations—such as stroke survivors and people with Parkinson’s disease—and are associated with increased gait instability and fall risk. Current methods to alter gait asymmetries rely heavily on split-belt treadmill training. Gait training using visual cues projected on a screen or in immersive virtual reality have been shown to produce greater improvements in gait asymmetries relative to traditional treadmill training alone. However, it is unclear the extent to which gait asymmetries can be systematically altered using an asymmetric visual cue, which represents a more cost-effective strategy relative to split-belt treadmill training or immersive virtual reality. Investigating whether using a visual asymmetric cue can alter gait symmetry in healthy adults is the first step in determining if this methodology is plausible for future research with clinical populations. The purpose of this dissertation was threefold: (1) to examine the extent to which healthy adults can synchronize to an asymmetric visual cue during treadmill walking; (2) to explore if the asymmetric walking pattern is retained once the visual cue is removed; and (3) to examine transfer of the asymmetric walking pattern to overground walking after the treadmill training session. Seventy-two healthy participants (age 23.89 ± 6.08 years) were enrolled in this study and quasi-randomized into four experimental groups (N = 64) or the control group (N = 8). All participants completed questionnaires related to health history/demographics, limb dominance, and physical activity. All groups completed three 10-minute walking sessions with wearable sensors (APDM Inc., Portland, OR) to record spatiotemporal gait measures. The first session was the same for all groups and consisted of walking at their self-selected speed on the treadmill. For session two, experimental groups 1 and 2 attempted to synchronize their gait to a visual cue (i.e., walking stick figure) exhibiting a small gait asymmetry presented on the projection screen in front of that treadmill, while experimental groups 3 and 4 attempted to synchronize their gait to a visual cue with a large gait asymmetry. For the third session, groups 1 and 3 walked on the treadmill for 10 minutes after the visual cue was removed, while groups 2 and 4 walked for 10 minutes overground after the treadmill training. The dependent variables were calculated using the Symmetry Index (SI) equation: stride length SI %, step duration SI %, and single limb support SI %. Visually inspecting the data showed some participants responded to the visual cue stimulus, while others did not. Therefore, experimental groups were further divided into responders (N = 42) and non-responders (N = 22). Wilcoxon Signed Rank and Mann Whitney U tests were run to determine if the gait asymmetry metrics differed from baseline to adaptation, adaptation to post adaptation and between groups, and Wilcoxon effect sizes were calculated to determine the magnitude of the effect. The results reported in Manuscript I show gait asymmetries increased in the small and large asymmetry responder groups; the effect sizes were moderate to large. However, no changes were shown in the small and large asymmetry non-responder groups; the effect sizes were small to moderate. The results from Manuscript II show that the small asymmetry responder group has reduced gait asymmetries during retention, yet some gait asymmetry metrics remain elevated in the large gait asymmetry responder group during retention. The gait asymmetry responder groups revealed decreases in almost all gait asymmetry metrics indicating the adopted gait pattern did not transfer to overground walking. No gait asymmetry changes were observed for the non-responder groups for retention or transfer. Collectively, the results suggest that an asymmetric visual cue can be used to alter gait symmetry and retention may be observed as such training. However, further research should investigate why some participants did not respond to the visual cue

Climbing and Walking Robots

Nowadays robotics is one of the most dynamic fields of scientific researches. The shift of robotics researches from manufacturing to services applications is clear. During the last decades interest in studying climbing and walking robots has been increased. This increasing interest has been in many areas that most important ones of them are: mechanics, electronics, medical engineering, cybernetics, controls, and computers. Today’s climbing and walking robots are a combination of manipulative, perceptive, communicative, and cognitive abilities and they are capable of performing many tasks in industrial and non- industrial environments. Surveillance, planetary exploration, emergence rescue operations, reconnaissance, petrochemical applications, construction, entertainment, personal services, intervention in severe environments, transportation, medical and etc are some applications from a very diverse application fields of climbing and walking robots. By great progress in this area of robotics it is anticipated that next generation climbing and walking robots will enhance lives and will change the way the human works, thinks and makes decisions. This book presents the state of the art achievments, recent developments, applications and future challenges of climbing and walking robots. These are presented in 24 chapters by authors throughtot the world The book serves as a reference especially for the researchers who are interested in mobile robots. It also is useful for industrial engineers and graduate students in advanced study

On Walking

Imagine the anatomy of architecture as a complex system, where the form is the result of generative processes, the material properties of the components, and their patterns of assembly. Within this paradigm, surface is that part of the system which exchanges energy, information, and materials with the local environment. How does human occupation of a space offer energy, information, or material to the system-building, and how can the surface best vector these exchanges? Walking could represent human occupation in this context. I choose my walker’s lineage and declare my interest, as an architect, in empathetic space. I explore the history of bipedalism, of the path as an architectural object, and of the sciences, philosophies and poetries of walkers. And I browse through contemporary architectural discourse pertaining to emergent design methodologies. Along the way, I test my proposal in two experiments: one complete, and one in progress..