Matching Items (10)
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- All Subjects: Biomechanics
- Creators: Harrington Bioengineering Program
- Creators: Redkar, Sangram
Description
Human running requires extensive training and conditioning for an individual to maintain high speeds (greater than 10mph) for an extended duration of time. Studies have shown that running at peak speeds generates a high metabolic cost due to the use of large muscle groups in the legs associated with the human gait cycle. Applying supplemental external and internal forces to the human body during the gait cycle has been shown to decrease the metabolic cost for walking, allowing individuals to carry additional weight and walk further distances. Significant research has been conducted to reduce the metabolic cost of walking, however, there are few if any documented studies that focus specifically on reducing the metabolic cost associated with high speed running. Three mechanical systems were designed to work in concert with the human user to decrease metabolic cost and increase the range and speeds at which a human can run.
The methods of design require a focus on mathematical modeling, simulations, and metabolic cost. Mathematical modeling and simulations are used to aid in the design process of robotic systems and metabolic testing is regarded as the final analysis process to determine the true effectiveness of robotic prototypes. Metabolic data, (VO2) is the volumetric consumption of oxygen, per minute, per unit mass (ml/min/kg). Metabolic testing consists of analyzing the oxygen consumption of a test subject while performing a task naturally and then comparing that data with analyzed oxygen consumption of the same task while using an assistive device.
Three devices were designed and tested to augment high speed running. The first device, AirLegs V1, is a mostly aluminum exoskeleton with two pneumatic linear actuators connecting from the lower back directly to the user's thighs, allowing the device to induce a torque on the leg by pushing and pulling on the user's thigh during running. The device also makes use of two smaller pneumatic linear actuators which drive cables connecting to small lever arms at the back of the heel, inducing a torque at the ankles. Device two, AirLegs V2, is also pneumatically powered but is considered to be a soft suit version of the first device. It uses cables to interface the forces created by actuators located vertically on the user's back. These cables then connect to the back of the user's knees resulting in greater flexibility and range of motion of the legs. Device three, a Jet Pack, produces an external force against the user's torso to propel a user forward and upward making it easier to run. Third party testing, pilot demonstrations and timed trials have demonstrated that all three of the devices effectively reduce the metabolic cost of running below that of natural running with no device.
The methods of design require a focus on mathematical modeling, simulations, and metabolic cost. Mathematical modeling and simulations are used to aid in the design process of robotic systems and metabolic testing is regarded as the final analysis process to determine the true effectiveness of robotic prototypes. Metabolic data, (VO2) is the volumetric consumption of oxygen, per minute, per unit mass (ml/min/kg). Metabolic testing consists of analyzing the oxygen consumption of a test subject while performing a task naturally and then comparing that data with analyzed oxygen consumption of the same task while using an assistive device.
Three devices were designed and tested to augment high speed running. The first device, AirLegs V1, is a mostly aluminum exoskeleton with two pneumatic linear actuators connecting from the lower back directly to the user's thighs, allowing the device to induce a torque on the leg by pushing and pulling on the user's thigh during running. The device also makes use of two smaller pneumatic linear actuators which drive cables connecting to small lever arms at the back of the heel, inducing a torque at the ankles. Device two, AirLegs V2, is also pneumatically powered but is considered to be a soft suit version of the first device. It uses cables to interface the forces created by actuators located vertically on the user's back. These cables then connect to the back of the user's knees resulting in greater flexibility and range of motion of the legs. Device three, a Jet Pack, produces an external force against the user's torso to propel a user forward and upward making it easier to run. Third party testing, pilot demonstrations and timed trials have demonstrated that all three of the devices effectively reduce the metabolic cost of running below that of natural running with no device.
ContributorsKerestes, Jason (Author) / Sugar, Thomas (Thesis advisor) / Redkar, Sangram (Committee member) / Rogers, Bradley (Committee member) / Arizona State University (Publisher)
Created2014
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
The global population over the age of 60 is estimated to rise to 23% by 2050 only increase the prevalence of functional neurological disorders and stroke. Increase in cases of functional neurological disorders and strokes will place a greater burden on the healthcare industry, specifically physical therapy. Physical therapy is vital for a patient’s recovery of motor function which is time demanding and taxing on the physical therapist. Wearable robotics have been proven to improve functional outcomes in gait rehabilitation by providing controlled high dosage and high-intensity training. Accurate control strategies for assistive robotic exoskeletons are vital for repetitive high precisions assistance for cerebral plasticity to occur.
This thesis presents a preliminary determination and design of a control algorithm for an assistive ankle device developed by the ASU RISE Laboratory. The assistive ankle device functions by compressing a spring upon heel strike during gait, remaining compressed during mid-stance and then releasing upon initiation of heel-off. The relationship between surface electromyography and ground reactions forces were used for identification of user-initiated heel-off. The muscle activation of the tibialis anterior combined with the ground reaction forces of the heel pressure sensor generated potential features that will be utilized in the revised control algorithm for the assistive ankle device. Work on this project must proceed in order to test and validate the revised control algorithm to determine its accuracy and precision.
This thesis presents a preliminary determination and design of a control algorithm for an assistive ankle device developed by the ASU RISE Laboratory. The assistive ankle device functions by compressing a spring upon heel strike during gait, remaining compressed during mid-stance and then releasing upon initiation of heel-off. The relationship between surface electromyography and ground reactions forces were used for identification of user-initiated heel-off. The muscle activation of the tibialis anterior combined with the ground reaction forces of the heel pressure sensor generated potential features that will be utilized in the revised control algorithm for the assistive ankle device. Work on this project must proceed in order to test and validate the revised control algorithm to determine its accuracy and precision.
ContributorsGaytan-Jenkins, Daniel Rinaldo (Author) / Zhang, Wenlong (Thesis director) / Tyler, Jamie (Committee member) / Harrington Bioengineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
With dwindling water resources due to drought and other pressures, water utilities are seeking to tap into alternative water sources as a means to improve water sustainability. Reclaimed water consists of treated wastewater and is widely used for non-potable purposes, such as irrigation, both agricultural and recreational. However, the reclaimed water distribution system can be subject to substantial regrowth of microorganisms, including opportunistic pathogens, even following rigorous disinfection. Factors that can influence regrowth include temperature, organic carbon levels, disinfectant type, and the time transported (i.e., water age) in the system. One opportunistic pathogen (OP) that is critical to understanding microbial activity in both reclaimed and drinking water distribution systems is Acanthamoeba. In order to better understand the potential for this amoeba to proliferate in reclaimed water systems and influence other OPs, a simulated reclaimed water distribution system was studied. The objective of this study was to compare the prevalence of Acanthamoeba and one of its endosymbionts, Legionella, across varying assimilable organic carbon (AOC) levels, temperatures, disinfectants, and water ages in a simulated reclaimed water distribution system. The results of the study showed that cooler temperatures, larger water age, and chlorine conditions yielded the lowest detection of Acanthamoeba gene copies per mL or cm2 for bulk water and biofilm samples, respectively.
ContributorsDonaldson, Kandace (Author) / Ankeny, Casey (Thesis director) / Edwards, Marc (Committee member) / Pruden, Amy (Committee member) / Harrington Bioengineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
The effect of conflicting sensorimotor memories on optimal force strategies was explored. Subjects operated a virtual object controlled by a physical handle to complete a simple straight-line task. Perturbations applied to the handle induced a period of increased error in subject accuracy. After two blocks of 33 trials, perturbations switched direction, inducing increased error from the previous trials. Subjects returned after a 24-hour period to complete a similar protocol, but beginning with the second context and ending with the first. Interference from the first context on each day caused an increase in initial error for the second (P < 0.05). Following the rest period, subjects showed retention of the sensorimotor memory from the previous day through significantly decreased initial error (P = 3x10-6). However, subjects showed an increase in forces for each new context resulting from a sub-optimal motor strategy. Higher levels of total effort (P < 0.05) and a lack of separation between force values for opposing and non-opposing digits (P > 0.05) indicated a strategy that used more energy to complete the task, even when rates of learning appeared identical or improved. Two possible mechanisms for this lack of energy conservation have been proposed.
ContributorsSmith, Michael David (Author) / Santello, Marco (Thesis director) / Kleim, Jeffrey (Committee member) / Harrington Bioengineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Medial compartment knee osteoarthritis (OA) is a disease whose severity has been associated with the peak adduction moment during walking (pKAM). Unfortunately, measuring patients' pKAM to track their therapy progress involves the use of a gait laboratory which is expensive and time intensive. This study aimed to develop and assess a regression method to predict the pKAM using only plantar pressure measurements. This approach could greatly reduce the burden of evaluating pKAM.
ContributorsThomas, Kevin Andrew (Author) / Hinrichs, Richard (Thesis director) / Harper, Erin (Committee member) / Favre, Julien (Committee member) / Barrett, The Honors College (Contributor) / Harrington Bioengineering Program (Contributor)
Created2014-05
Description
According to the Center for Disease Control and Prevention report around 29,668 United States residents aged greater than 65 years had died as a result of a fall in 2016. Other injuries like wrist fractures, hip fractures, and head injuries occur as a result of a fall. Certain groups of people are more prone to experience falls than others, one of which being individuals with stroke. The two most common issues with individuals with strokes are ankle weakness and foot drop, both of which contribute to falls. To mitigate this issue, the most popular clinical remedy given to these users is thermoplastic Ankle Foot Orthosis. These AFO's help improving gait velocity, stride length, and cadence. However, studies have shown that a continuous restraint on the ankle harms the compensatory stepping response and forward propulsion. It has been shown in previous studies that compensatory stepping and forward propulsion are crucial for the user's ability to recover from postural perturbations. Hence, there is a need for active devices that can supply a plantarflexion during the push-off and dorsiflexion during the swing phase of gait. Although advancements in the orthotic research have shown major improvements in supporting the ankle joint for rehabilitation, there is a lack of available active devices that can help impaired users in daily activities. In this study, our primary focus is to build an unobtrusive, cost-effective, and easy to wear active device for gait rehabilitation and fall prevention in individuals who are at risk. The device will be using a double-acting cylinder that can be easily incorporated into the user's footwear using a novel custom-designed powered ankle brace. The device will use Inertial Measurement Units to measure kinematic parameters of the lower body and a custom control algorithm to actuate the device based on the measurements. The study can be used to advance the field of gait assistance, rehabilitation, and potentially fall prevention of individuals with lower-limb impairments through the use of Active Ankle Foot Orthosis.
ContributorsRay, Sambarta (Author) / Honeycutt, Claire (Thesis advisor) / Dasarathy, Gautam (Thesis advisor) / Redkar, Sangram (Committee member) / Jayasuriya, Suren (Committee member) / Arizona State University (Publisher)
Created2020
Description
Human walking is a complex and rhythmical activity that comprises of the brain, nerves and muscles. Neuromuscular disorder (NMD) is a broad term that refers to conditions that affect the proper use of muscles and nervous system, thus also impairing the walking or gait cycle of an individual. The improper gait cycle might be attributed to the lack of force produced at the toe-off stage. This project addresses if it is possible to create an OpenSim model to find the ideal time and force magnitude needed of an assistive force ankle device to improve gait patterns in individuals with NMD.
ContributorsRivera, Jose Luis (Author) / Zhang, Wenlong (Thesis director) / Lockhart, Thurmon (Committee member) / Harrington Bioengineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Over the past 30 years the use of graphene has been increasing at a rapid rate. The reason why graphene has become more popular is because it is starting to be understood better, and researchers are starting to recognize graphene’s unique properties. Graphene is a single atomic layer of graphite, and graphite is a three-dimensional cube base structure of carbon. Graphite has a high conductivity rate, and graphene has an even higher conductivity, meaning that graphene makes for an excellent resistor in any hardware system. Graphene is flexible, has high durability, and can vary in resistance based on its shape (Sharon 2015). With graphene being able to change its resistivity, it can act as different types of sensors. These sensors include measuring pressure, resistance, force, strain, and angle. One problem across the globe is that patients have arthritis, decaying bone density, and injuries which can easily go mistreated or not treated at all. It can be hard to determine the severity of injuries in joints by observation of the patient. There are tools and equipment that will allow a doctor to track the force and degrees of motion of certain joints, but they are mostly limited to hospitals. With graphene acting as a sensor it can be embedded into casts, braces, and even clothing. With a mobile sensor that relays accurate and continuous data to a doctor they can more precisely determine a therapy or recovery time that will better suit the patients’ needs. In this project the graphene was used to measure the angle of a patient’s wrist while they were wearing a wrist brace. From the data collected, the graphene was able to track the user’s movement of their wrist as they moved it in a single direction. The data showed the angle of the wrist ranging from zero degrees to 90 degrees. This proves that graphene can shape the way biosensing is accomplished. Biodynamics is a growing field, and with more injuries everyday it is important to study graphene and how it can be used to diagnose and prevent injuries related to joints. Graphene can be used as a biosensor which can then be implemented into a brace to allow for accurate biodynamic tracking.
ContributorsSweeten, William (Author) / Lockhart, Thurmon (Thesis director) / Helms Tillery, Stephen (Committee member) / Harrington Bioengineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
The field of prostheses and rehabilitation devices has seen tremendous advancement since the ’90s. However, the control aspect of the said devices is lacking. The need for mathematical theories to improve the control strategies is apparent. This thesis attempts to bridge the gap by introducing some dynamic system analysis and control strategies.Firstly, the human gait dynamics are assumed to be periodic. Lyapunov Floquet theory and Invariant manifold theory are applied. A transformation is obtained onto a simple single degree of freedom oscillator system. The said system is transformed back into the original domain and compared to the original system. The results are discussed and critiqued. Then the technique is applied to the kinematic and kinetic data collected from healthy human subjects to verify the technique’s feasibility. The results show that the technique successfully reconstructed the kinematic and kinetic data.
Human gait dynamics are not purely periodic, so a quasi-periodic approach is adopted. Techniques to reduce the order of a quasi-periodic system are studied. Lyapunov-Peron transformation (a surrogate of Lyapunov Floquet transformation for quasi-periodic systems) is studied. The transformed system is easier to control. The inverse of the said transformation is obtained to transform back to the original domain. The application of the techniques to different cases (including externally forced systems) is studied.
The reduction of metabolic cost is presented as a viable goal for applying the previously studied control techniques. An experimental protocol is designed and executed to understand periodic assistive forces' effects on human walking gait. Different tether stiffnesses are used to determine the best stiffness for a given subject population. An estimation technique is introduced to obtain the metabolic cost using the center of mass's kinematic data.
Lastly, it is concluded that the mathematical techniques can be utilized in a robotic tail-like rehabilitation device. Some possible future research ideas are provided to implement the techniques mentioned in this dissertation.
ContributorsBhat, Sandesh Ganapati (Author) / Redkar, Sangram (Thesis advisor) / Sugar, Thomas G (Committee member) / Rogers, Bradley (Committee member) / Arizona State University (Publisher)
Created2021