Walking comes naturally to us and appears to be simple. However, this is not so and it is known that walking requires high level neural control and muscle coordination. There is no single, unifying theory of bipedal walking. Models of walking are useful in various ways such as developing computational theories of neural control, understanding muscle coordination and to design and analyze lower extremity prostheses. This thesis deals with modeling and simulation of walking from a kinematics and dynamics view point. Three sagittal planar models with increasing levels of complexity are presented in this thesis. The first model is a simple two degrees of freedom (DoF) model representing the motion at the hip and the knee joint. The second model is a three DoF model where the ankle joint motion is also taken into account. Finally, the third model considers both the legs and has seven DoF. The kinematic and dynamic equations of the models are derived, and the inverse dynamic analysis and forward dynamic simulation of the models are performed. The simulation results are compared with experimental data available in literature.

This thesis discusses walking robots issues, their classification, management and construction. There are listed the most famous motion algorithms and their graphical representation. Examples of existing walking robots are also mentioned in this thesis. There are also described modifications of hexapod robot, its hardware and software. The robot is controlled through graphical user interface, which displays data from all sensors, visualises positions of all legs and allows the creation of user defined gaits and its simulations.

No description available.

Background: Physical functioning and mobility of older populations are of increasing interest when populations are aging. Lower body functioning such as walking is a fundamental part of many actions in daily life. Limitations in mobility threaten independent living as well as quality of life in old age. In this study we examine differences in physical aging and convert those differences into the everyday measure of single years of age. Methods: We use the English Longitudinal Study of Ageing, which was collected biennially between 2002 and 2012. Data on physical performance, health as well as information on economics and demographics of participants were collected. Lower body performance was assessed with two timed walks at normal pace each of 8 ft (2.4 m) of survey participants aged at least 60 years. We employed growth curve models to study differences in physical aging and followed the characteristic-based age approach to illustrate those differences in single years of age. Results: First, we examined walking speed of about 11,700 English individuals, and identified differences in aging trajectories by sex and other characteristics (e.g. education, occupation, regional wealth). Interestingly, higher educated and non-manual workers outperformed their counterparts for both men and women. Moreover, we transformed the differences between subpopulations into single years of age to demonstrate the magnitude of those gaps, which appear particularly high at early older ages. Conclusions: This paper expands research on aging and physical performance. In conclusion, higher education provides an advantage in walking of up to 15 years for men and 10 years for women. Thus, enhancements in higher education have the potential to ensure better mobility and independent living in old age for a longer period. (author's Abstract)

published_or_final_version / Community Medicine / Master / Master of Public Health

Recent studies have suggested the biomechanical subtasks of walking can be produced using a reduced set of co-excited muscles or modules. Individuals post-stroke often exhibit poor inter-muscular coordination characterized by poor timing and merging of modules that are normally independent in healthy individuals. However, whether locomotor therapy can influence module quality (timing and composition) and whether these improvements lead to improved walking performance is unclear. Further, it is unknown whether the same modules that produce self-selected walking can also produce the execution of different mobility tasks. In this study, experimental analyses were used to compare module quality pre- and post-therapy. In subjects with four modules pre- and post-therapy, locomotor training resulted in improved timing of the ankle plantarflexor module and a more extended paretic leg angle that allowed the subjects to walk faster with more symmetrical propulsion. In addition, subjects with three modules pre-therapy increased their number of modules and improved walking performance post-therapy. Thus, locomotor training was found to influence module composition and timing, which can lead to improvements in walking performance. Experimental and simulation analyses were then used to characterize modular organization in specific mobility tasks (walking at self-selected speed with maximum cadence, maximum step length, and maximum step height). We found that the same underlying modules (number and composition) in each subject that contribute to steady-state walking also contribute to the different mobility tasks. In healthy subjects, module timing, but not composition, changed when the task demands were altered. This adaptability in module timing, in addition to the ability to adapt to the changing task demands, was limited in the post-stroke subjects. The primary difference in the execution of the walking biomechanical subtasks occurred in the control of the leg during pre-swing and swing. To increase cadence, the ankle plantarflexors and dorsiflexors contributed more power to the ipsilateral leg in pre-swing and swing, respectively. To increase step height, the hamstrings provided energy to the ipsilateral leg that accelerated the leg into swing in pre-swing and swing. These results provide a first step towards linking impaired module patterns to mobility task performance in persons post-stroke. / text

No description available.

In the past decade, society has become increasingly dependent on portable electronic devices that are almost exclusively powered by batteries. The performance and duration of operation of these devices are constrained by the limited energy per unit mass of batteries. Recent advances in the field of energy harvesting have led to the development of efficient and sustainable technologies that are capable of collecting mechanical energy from human motion, and producing the electrical power required to operate portable devices. This thesis focuses on the design and evaluation of a motion-based biomechanical energy harvester that collects energy from the user’s lower limbs. Two lower-limb energy-driven harvesting backpacks, a belt-driven prototype and a gear-driven prototype, were developed. Human treadmill walking testing showed that the belt-driven prototype was able to produce 19.3-12.2W of electrical power with a device efficiency of 34.4-48.4%. The belt-driven prototype had a low metabolic cost of carrying the device, approximately 18W, but had a large metabolic cost of producing electrical power, approximately 188W. This large metabolic cost of energy production is likely a consequence of the large mechanical power required to drive the device, namely to overcome the moment of inertia and the frictional loss of the device. Preliminary testing of the gear-driven prototype showed that the device was able to produce 7-11.2W of electrical power with a device efficiency of 58-78%. A theoretical model was developed that was able to predict the harvester0s electrical power output and the respective load on the user, from a given input motion wave-form. This model was able to predict the peak voltage and peak force with a percent difference of 2% ± 2% and 6.4% ± 4% respectively. Further reduction of the volume, weight, and number of parts of the energy harvester is essential in making the harvester a viable commercial product for powering portable devices. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2013-08-27 10:46:27.16

<p>Relationships between motor development and language abilities have been consistently reported in previous literature. One of the relationships that has becoming increasing popular is the link between walking and language. Whereas research has demonstrated that onset of walking is related to communicative skills and vocabulary abilities (e.g., Clearfield, 2011; Walle & Campos, 2014), the mechanism underlying this relationship remains unclear. One potential explanation is that walking increases young children’s opportunities to interact with objects and explore the environment. Young children’s ability to adapt gait while playing is necessary for successful navigation of their environment and may be one factor underlying the walking-language relationship. However, little research has examined how young children adapt gait when interacting with objects in their environment when they are free to walk in a naturalistic manner. Additionally, how young children’s gait control and behavior during free-play is related to word learning has also been understudied. The purpose of this dissertation was to quantify how new and experienced walkers adapt gait behavior based on task (carrying objects compared to not carrying objects) and environmental constraints (free-play versus straight-path) and assess how these behaviors may be related to language abilities early in development. </p> <p><br></p><p>Chapter 3 examined how object carriage impacts gait characteristics and behavioral measures of stability during free-play and a straight-path task. New (13-month-olds) and experienced (24-month-olds) walkers engaged in a 20-minute free-play session with their parents. Eighteen toys that varied in size and weight were provided. Following the free-play session, new and experienced walkers engaged in a straight-path task where they were encouraged to walk from their parents to the experimenter, take a toy, and carry the toy back to their parent. Overall, size and weight did not appear to impact lower-body gait characteristics. Although there were no differences in lower-body gait control when carrying a toy compared to not carrying a toy, there were individual differences in how young children adapted their step length, step width, and stride speed with some children adopting more mature gait characteristics and others adopting less mature gait patterns. Young children’s lower-body gait also differed based on environmental constraints (free-play versus straight-path task). In addition to these lower-body findings, new and experienced walkers also adapted their upper-body control when carrying toys in both free-play and the straight-path task. New walkers also appear to focus on weight of the toy when selecting toys to carry whereas experienced walkers did not demonstrate preference for specific toy characteristics. </p> <p><br></p><p>Chapter 4 assessed the relationship between gait characteristics and functional behavior during free-play and communicative/vocabulary abilities in new and experienced walkers. Thirty-eight new walkers and thirty-eight experienced walkers from Chapter 3 were included in the analyses. Additionally, thirteen new walkers also returned at 24-months and repeated the data collection procedure for a longitudinal analysis of these relationships. The protocol for Chapter 3 was the same as Chapter 4; however, only free-play measures were included in the analyses. Parents also filled out the age-appropriate version of the MacArthur-Bates Communicative Development Inventory as a measure of communicative/vocabulary abilities. Overall, the results of Chapter 4 demonstrated that quality of upper-body gait control and time spent in motion were significant predictors of new walkers’ communicative skills and vocabulary abilities. Whereas these relationships were not apparent in the experienced walking group, quality of gait at 13-months was predictive of productive vocabulary scores at 24-months of age. </p> <p><br></p><p>Taken together, the results from these studies suggest that examining gait behavior during free-play reveals how complex young children’s navigation of their environment is. Furthermore, these early movements and functional behavior during free-play may be important predictors underlying the relationship between onset of walking and language development.</p>

This project documents my process of visual and hermeneutic enquiry centred on the Tswaing meteorite impact crater, north of Pretoria. In my visual investigation I attempt to apprehend the landscape through a cyclical process which involves walking within it, photographing it in 360° ‘visualisations’, editing the imagery and returning, often frustrated, to repeat both encounter and process. The cycle of reflection leads me to consider my circular process itself as a dialogical mode of interpretation and response to the primeval, circular landscape of the impact crater. Informed by Gadamer’s (1975) notion of a hermeneutic circle which extends interpretation and understanding, the reflexive process is extended and enriched through dialogue with the work of pertinent scientists, artists, poets and writers. Landscape is considered as an artefact of deep time, challenging entrenched traditions and notions while considering significant contemporary responses. The dissertation attempts to demonstrate the layered accretion of concept and meaning contained within the visual and theoretical components of the investigation