Matching Items (21)
Description
Gait and balance disorders are the second leading cause of falls in the elderly. Investigating the changes in static and dynamic balance due to aging may provide a better understanding of the effects of aging on postural control system. Static and dynamic balance were evaluated in a total of 21 young (21-35 years) and 22 elderly (50-75 years) healthy subjects while they performed three different tasks: quiet standing, dynamic weight shifts, and over ground walking. During the quiet standing task, the subjects stood with their eyes open and eyes closed. When performing dynamic weight shifts task, subjects shifted their Center of Pressure (CoP) from the center target to outward targets and vice versa while following real-time feedback of their CoP. For over ground walking tasks, subjects performed Timed Up and Go test, tandem walking, and regular walking at their self-selected speed. Various quantitative balance and gait measures were obtained to evaluate the above respective balance and walking tasks. Total excursion, sway area, and mean frequency of CoP during quiet standing were found to be the most reliable and showed significant increase with age and absence of visual input. During dynamic shifts, elderly subjects exhibited higher initiation time, initiation path length, movement time, movement path length, and inaccuracy indicating deterioration in performance. Furthermore, the elderly walked with a shorter stride length, increased stride variability, with a greater turn and turn-to-sit duration. Significant correlations were also observed between measures derived from the different balance and gait tasks. Thus, it can be concluded that aging deteriorates the postural control system affecting static and dynamic balance and some of the alterations in CoP and gait measures may be considered as protective mechanisms to prevent loss of balance.
ContributorsBalasubramanian, Shruthi (Author) / Krishnamurthi, Narayanan (Thesis advisor) / Abbas, James (Thesis advisor) / Buneo, Christopher (Committee member) / Arizona State University (Publisher)
Created2014
Description
Although tremor, rigidity, and bradykinesia are cardinal symptoms of Parkinson's disease (PD), impairments of gait and balance significantly affect quality of life, especially as the disease progresses, and do not respond well to anti-parkinsonism medications. Many studies have shown that people with PD can walk better when appropriate cues are presented but, to the best of our knowledge, the effects of real-time feedback of step length and uprightness of posture on gait and posture have not been specifically investigated. If it can be demonstrated that real-time feedback can improve posture and gait, the resultant knowledge could be used to design effective rehabilitation strategies to improve quality of life in this population.
In this feasibility study, we have developed a treadmill-based experimental paradigm to provide feedback of step length and upright posture in real-time. Ten subjects (mean age 65.9 ± 7.6 years) with mild to moderate PD (Hoehn and Yahr stage III or below) were evaluated in their ability to successfully utilize real-time feedback presented during quiet standing and treadmill walking tasks during a single data collection session in their medication-on state. During quiet standing tasks in which back angle feedback was provided, subjects were asked to utilize the feedback to maintain upright posture. During treadmill walking tasks, subjects walked at their self-selected speed for five minutes without feedback, with feedback of back angle, or with feedback of step length. During walking tasks with back angle feedback, subjects were asked to utilize the feedback to maintain upright posture. During walking tasks with step length feedback, subjects were asked to utilize the feedback to walk with increased step length. During quiet standing tasks, measurements of back angle were obtained; during walking tasks, measurements of back angle, step length, and step time were obtained.
Subjects stood and walked with significantly increased upright posture during the tasks with real-time back angle feedback compared to tasks without feedback. Similarly, subjects walked with significantly increased step length during tasks with real-time step length feedback compared to tasks without feedback. These results demonstrate that people with PD can utilize real-time feedback to improve upright posture and gait.
In this feasibility study, we have developed a treadmill-based experimental paradigm to provide feedback of step length and upright posture in real-time. Ten subjects (mean age 65.9 ± 7.6 years) with mild to moderate PD (Hoehn and Yahr stage III or below) were evaluated in their ability to successfully utilize real-time feedback presented during quiet standing and treadmill walking tasks during a single data collection session in their medication-on state. During quiet standing tasks in which back angle feedback was provided, subjects were asked to utilize the feedback to maintain upright posture. During treadmill walking tasks, subjects walked at their self-selected speed for five minutes without feedback, with feedback of back angle, or with feedback of step length. During walking tasks with back angle feedback, subjects were asked to utilize the feedback to maintain upright posture. During walking tasks with step length feedback, subjects were asked to utilize the feedback to walk with increased step length. During quiet standing tasks, measurements of back angle were obtained; during walking tasks, measurements of back angle, step length, and step time were obtained.
Subjects stood and walked with significantly increased upright posture during the tasks with real-time back angle feedback compared to tasks without feedback. Similarly, subjects walked with significantly increased step length during tasks with real-time step length feedback compared to tasks without feedback. These results demonstrate that people with PD can utilize real-time feedback to improve upright posture and gait.
ContributorsJellish, Jeremy (Author) / Abbas, James (Thesis advisor) / Krishnamurthi, Narayanan (Thesis advisor) / Ingalls, Todd (Committee member) / Arizona State University (Publisher)
Created2014
Description
Multiple Sclerosis, an autoimmune disease, is one of the most common neurological disorder in which demyelinating of the axon occurs. The main symptoms of MS disease are fatigue, vision problems, stability issue, balance problems. Unfortunately, currently available treatments for this disease do not always guarantee the improvement of the condition of the MS patient and there has not been an accurate mechanism to measure the effectiveness of the treatment due to inter-patient heterogeneity. The factors that count for varying the performance of MS patients include environmental setting, weather, psychological status, dressing style and more. Also, patients may react differently while examined at specially arranged setting and this may not be the same while he/she is at home. Hence, it becomes a major problem for MS patients that how effectively a treatment slows down the progress of the disease and gives a relief for the patient. This thesis is trying to build a reliable system to estimate how good a treatment is for MS patients. Here I study the kinematic variables such as velocity of walking, stride length, variability and so on to find and compare the variations of the patient after a treatment given by the doctor, and trace these parameters for some patients after the treatment effect subdued.
ContributorsYin, Siyang (Author) / He, Jiping (Thesis advisor) / Pizziconi, Vincent (Committee member) / Towe, Bruce (Committee member) / Arizona State University (Publisher)
Created2012
Description
Lower-limb prosthesis users have commonly-recognized deficits in gait and posture control. However, existing methods in balance and mobility analysis fail to provide sufficient sensitivity to detect changes in prosthesis users' postural control and mobility in response to clinical intervention or experimental manipulations and often fail to detect differences between prosthesis users and non-amputee control subjects. This lack of sensitivity limits the ability of clinicians to make informed clinical decisions and presents challenges with insurance reimbursement for comprehensive clinical care and advanced prosthetic devices. These issues have directly impacted clinical care by restricting device options, increasing financial burden on clinics, and limiting support for research and development. This work aims to establish experimental methods and outcome measures that are more sensitive than traditional methods to balance and mobility changes in prosthesis users. Methods and analysis techniques were developed to probe aspects of balance and mobility control that may be specifically impacted by use of a prosthesis and present challenges similar to those experienced in daily life that could improve the detection of balance and mobility changes. Using the framework of cognitive resource allocation and dual-tasking, this work identified unique characteristics of prosthesis users’ postural control and developed sensitive measures of gait variability. The results also provide broader insight into dual-task analysis and the motor-cognitive response to demanding conditions. Specifically, this work identified altered motor behavior in prosthesis users and high cognitive demand of using a prosthesis. The residual standard deviation method was developed and demonstrated to be more effective than traditional gait variability measures at detecting the impact of dual-tasking. Additionally, spectral analysis of the center of pressure while standing identified altered somatosensory control in prosthesis users. These findings provide a new understanding of prosthetic use and new, highly sensitive techniques to assess balance and mobility in prosthesis users.
ContributorsHoward, Charla Lindley (Author) / Abbas, James (Thesis advisor) / Buneo, Christopher (Committee member) / Lynskey, Jim (Committee member) / Santello, Marco (Committee member) / Artemiadis, Panagiotis (Committee member) / Arizona State University (Publisher)
Created2017
Description
In this work, different passive prosthetic ankles are studied. It is observed that complicated designs increase the cost of production, but simple designs have limited functionality. A new design for a passive prosthetic ankle is presented that is simple to manufacture while having superior functionality. This prosthetic ankle design has two springs: one mimicking Achilles tendon and the other mimicking Anterior-Tibialis tendon. The dynamics of the prosthetic ankle is discussed and simulated using Working model 2D. The simulation results are used to optimize the springs stiffness. Two experiments are conducted using the developed ankle to verify the simulation It is found that this novel ankle design is better than Solid Ankle Cushioned Heel (SACH) foot. The experimental data is used to find the tendon and muscle activation forces of the subject wearing the prosthesis using OpenSim. A conclusion is included along with suggested future work.
ContributorsBhat, Sandesh Ganapati (Author) / Redkar, Sangram (Thesis advisor) / Sugar, Thomas (Committee member) / Lee, Hyuglae (Committee member) / Marvi, Hamid (Committee member) / Arizona State University (Publisher)
Created2017
Description
Lower-limb wearable assistive robots could alter the users gait kinematics by inputting external power, which can be interpreted as mechanical perturbation to subject normal gait. The change in kinematics may affect the dynamic stability. This work attempts to understand the effects of different physical assistance from these robots on the gait dynamic stability.
A knee exoskeleton and ankle assistive device (Robotic Shoe) are developed and used to provide walking assistance. The knee exoskeleton provides personalized knee joint assistive torque during the stance phase. The robotic shoe is a light-weighted mechanism that can store the potential energy at heel strike and release it by using an active locking mechanism at the terminal stance phase to provide push-up ankle torque and assist the toe-off. Lower-limb Kinematic time series data are collected for subjects wearing these devices in the passive and active mode. The changes of kinematics with and without these devices on lower-limb motion are first studied. Orbital stability, as one of the commonly used measure to quantify gait stability through calculating Floquet Multipliers (FM), is employed to asses the effects of these wearable devices on gait stability. It is shown that wearing the passive knee exoskeleton causes less orbitally stable gait for users, while the knee joint active assistance improves the orbital stability compared to passive mode. The robotic shoe only affects the targeted joint (right ankle) kinematics, and wearing the passive mechanism significantly increases the ankle joint FM values, which indicates less walking orbital stability. More analysis is done on a mechanically perturbed walking public data set, to show that orbital stability can quantify the effects of external mechanical perturbation on gait dynamic stability. This method can further be used as a control design tool to ensure gait stability for users of lower-limb assistive devices.
A knee exoskeleton and ankle assistive device (Robotic Shoe) are developed and used to provide walking assistance. The knee exoskeleton provides personalized knee joint assistive torque during the stance phase. The robotic shoe is a light-weighted mechanism that can store the potential energy at heel strike and release it by using an active locking mechanism at the terminal stance phase to provide push-up ankle torque and assist the toe-off. Lower-limb Kinematic time series data are collected for subjects wearing these devices in the passive and active mode. The changes of kinematics with and without these devices on lower-limb motion are first studied. Orbital stability, as one of the commonly used measure to quantify gait stability through calculating Floquet Multipliers (FM), is employed to asses the effects of these wearable devices on gait stability. It is shown that wearing the passive knee exoskeleton causes less orbitally stable gait for users, while the knee joint active assistance improves the orbital stability compared to passive mode. The robotic shoe only affects the targeted joint (right ankle) kinematics, and wearing the passive mechanism significantly increases the ankle joint FM values, which indicates less walking orbital stability. More analysis is done on a mechanically perturbed walking public data set, to show that orbital stability can quantify the effects of external mechanical perturbation on gait dynamic stability. This method can further be used as a control design tool to ensure gait stability for users of lower-limb assistive devices.
ContributorsRezayat Sorkhabadi, Seyed Mostafa (Author) / Zhang, Wenlong (Thesis advisor) / Lee, Hyunglae (Committee member) / Artemiadis, Panagiotis (Committee member) / Arizona State University (Publisher)
Created2018
Description
As life expectancy continually rises, many age-related conditions such as deteriorated gait and decreased stability begin to play a larger role in affecting the quality of life for all individuals. Medical expenses associated with falls in the elderly population surpassed $50 Billion in 2015 alone. Understanding fall risk and developing robust metrics and methods of assessment has become more important than ever. While traditional fall risk has looked at classical gait parameters, dynamic stability has gained traction as a more accurate representation of stability during active movement and daily activities. This project seeks to determine the effects on the internal perturbation of gait velocity on dynamic stability represented by the Maximal Lyapunov Exponent (MLE) of multiple acceleration vectors, as well as the efficacy of varying methodology used to assess dynamic stability. Data from 15 healthy, college aged individuals was collected. Significant differences were shown between certain gait velocity trials for one analysis of the three methods explored, while overall trends suggested potential differences between gait velocities with other methodologies warranting further investigation.
ContributorsKreisler, Itai Goeta (Author) / Lockhart, Thurmon (Thesis director) / Rezvanian, Saba (Committee member) / W.P. Carey School of Business (Contributor) / Harrington Bioengineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
Gait training therapies are methods for improving the walking stability of individuals who have difficulty walking, whether it is due to injury or neuromuscular conditions. Perturbation training that causes individuals to correct their balance and actively improve their stability could potentially lead to longer term benefits for those with unstable gait. Subjects had the medial lateral movement of their center of mass measured through motion-tracking software (D-Flow 3 and Vicon Nexus 2.2). Perturbation training completed with the GRAIL treadmill randomly triggered medial-lateral sway perturbations of 3 cm a total of fifteen times throughout a five minute training period. Data collected to compare baseline, post-training, and one week follow-up dynamic stabilities were recorded over three minutes without any perturbations. There were no statistically significant differences when comparing the results of all subjects at each instance of data collection with each other. Thus, the perturbation training had no significant impact on the dynamic stability of gait. Major limitations that lend to the inconclusive nature of this study include a small sample size, no repetitions, and only one round of training. Further work can be done to better assess the potential impacts of perturbation training on walking stability for therapeutic use.
ContributorsJamali, Neema (Author) / Lockhart, Thurmon (Thesis director) / Soangra, Rahul (Committee member) / School of Biological and Health Systems Engineering (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
Unmanned aerial vehicles have received increased attention in the last decade due to their versatility, as well as the availability of inexpensive sensors (e.g. GPS, IMU) for their navigation and control. Multirotor vehicles, specifically quadrotors, have formed a fast growing field in robotics, with the range of applications spanning from surveil- lance and reconnaissance to agriculture and large area mapping. Although in most applications single quadrotors are used, there is an increasing interest in architectures controlling multiple quadrotors executing a collaborative task. This thesis introduces a new concept of control involving more than one quadrotors, according to which two quadrotors can be physically coupled in mid-flight. This concept equips the quadro- tors with new capabilities, e.g. increased payload or pursuit and capturing of other quadrotors. A comprehensive simulation of the approach is built to simulate coupled quadrotors. The dynamics and modeling of the coupled system is presented together with a discussion regarding the coupling mechanism, impact modeling and additional considerations that have been investigated. Simulation results are presented for cases of static coupling as well as enemy quadrotor pursuit and capture, together with an analysis of control methodology and gain tuning. Practical implementations are introduced as results show the feasibility of this design.
ContributorsLarsson, Daniel (Author) / Artemiadis, Panagiotis (Thesis advisor) / Marvi, Hamidreza (Committee member) / Berman, Spring (Committee member) / Arizona State University (Publisher)
Created2016
Description
Human walking has been a highly studied topic in research communities because of its extreme importance to human functionality and mobility. A complex system of interconnected gait mechanisms in humans is responsible for generating robust and consistent walking motion over unpredictable ground and through challenging obstacles. One interesting aspect of human gait is the ability to adjust in order to accommodate varying surface grades. Typical approaches to investigating this gait function focus on incline and decline surface angles, but most experiments fail to address the effects of surface grades that cause ankle inversion and eversion. There have been several studies of ankle angle perturbation over wider ranges of grade orientations in static conditions; however, these studies do not account for effects during the gait cycle. Furthermore, contemporary studies on this topic neglect critical sources of unnatural stimulus in the design of investigative technology. It is hypothesized that the investigation of ankle angle perturbations in the frontal plane, particularly in the context of inter-leg coordination mechanisms, results in a more complete characterization of the effects of surface grade on human gait mechanisms. This greater understanding could potentially lead to significant applications in gait rehabilitation, especially for individuals who suffer from impairment as a result of stroke. A wearable pneumatic device was designed to impose inversion and eversion perturbations on the ankle through simulated surface grade changes. This prototype device was fabricated, characterized, and tested in order to assess its effectiveness. After testing and characterizing this device, it was used in a series of experiments on human subjects while data was gathered on muscular activation and gait kinematics. The results of the characterization show success in imposing inversion and eversion angle perturbations of approximately 9° with a response time of 0.5 s. Preliminary experiments focusing on inter-leg coordination with healthy human subjects show that one-sided inversion and eversion perturbations have virtually no effect on gait kinematics. However, changes in muscular activation from one-sided perturbations show statistical significance in key lower limb muscles. Thus, the prototype device demonstrates novelty in the context of human gait research for potential applications in rehabilitation.
ContributorsBarkan, Andrew (Author) / Artemiadis, Panagiotis (Thesis advisor) / Lee, Hyunglae (Committee member) / Marvi, Hamidreza (Committee member) / Arizona State University (Publisher)
Created2016