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Description
As the robotic industry becomes increasingly present in some of the more extreme environments such as the battle field, disaster sites or extraplanetary exploration, it will be necessary to provide locomotive niche strategies that are optimal to each terrain. The hopping gait has been well studied in robotics and

As the robotic industry becomes increasingly present in some of the more extreme environments such as the battle field, disaster sites or extraplanetary exploration, it will be necessary to provide locomotive niche strategies that are optimal to each terrain. The hopping gait has been well studied in robotics and proven to be a potential method to fit some of these niche areas. There have been some difficulties in producing terrain following controllers that maintain robust, steady state, which are disturbance resistant.

The following thesis will discuss a controller which has shown the ability to produce these desired properties. A phase angle oscillator controller is shown to work remarkably well, both in simulation and with a one degree of freedom robotic test stand.

Work was also done with an experimental quadruped with less successful results, but which did show potential for stability. Additional work is suggested for the quadruped.
ContributorsNew, Philip Wesley (Author) / Sugar, Thomas G. (Thesis advisor) / Artemiadis, Panagiotis (Committee member) / Redkar, Sangram (Committee member) / Arizona State University (Publisher)
Created2015
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Description
Wearable robots including exoskeletons, powered prosthetics, and powered orthotics must add energy to the person at an appropriate time to enhance, augment, or supplement human performance. Adding energy while not being in sync with the user can dramatically hurt performance making it necessary to have correct timing with the user.

Wearable robots including exoskeletons, powered prosthetics, and powered orthotics must add energy to the person at an appropriate time to enhance, augment, or supplement human performance. Adding energy while not being in sync with the user can dramatically hurt performance making it necessary to have correct timing with the user. Many human tasks such as walking, running, and hopping are repeating or cyclic tasks and a robot can add energy in sync with the repeating pattern for assistance. A method has been developed to add energy at the appropriate time to the repeating limit cycle based on a phase oscillator. The phase oscillator eliminates time from the forcing function which is based purely on the motion of the user. This approach has been simulated, implemented and tested in a robotic backpack which facilitates carrying heavy loads. The device oscillates the load of the backpack, based on the motion of the user, in order to add energy at the correct time and thus reduce the amount of energy required for walking with a heavy load. Models were developed in Working Model 2-D, a dynamics simulation software, in conjunction with MATLAB to verify theory and test control methods. The control system developed is robust and has successfully operated on a range of different users, each with their own different and distinct gait. The results of experimental testing validated the corresponding models.
ContributorsWheeler, Chase (Author) / Sugar, Thomas G. (Thesis advisor) / Redkar, Sangram (Thesis advisor) / Artemiadis, Panagiotis (Committee member) / Arizona State University (Publisher)
Created2014
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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

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.
ContributorsKerestes, Jason (Author) / Sugar, Thomas (Thesis advisor) / Redkar, Sangram (Committee member) / Rogers, Bradley (Committee member) / Arizona State University (Publisher)
Created2014
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Description
Multiple robotic arms collaboration is to control multiple robotic arms to collaborate with each other to work on the same task. During the collaboration, theagent is required to avoid all possible collisions between each part of the robotic arms. Thus, incentivizing collaboration and preventing collisions are the two principles which are followed

Multiple robotic arms collaboration is to control multiple robotic arms to collaborate with each other to work on the same task. During the collaboration, theagent is required to avoid all possible collisions between each part of the robotic arms. Thus, incentivizing collaboration and preventing collisions are the two principles which are followed by the agent during the training process. Nowadays, more and more applications, both in industry and daily lives, require at least two arms, instead of requiring only a single arm. A dual-arm robot satisfies much more needs of different types of tasks, such as folding clothes at home, making a hamburger in a grill or picking and placing a product in a warehouse. The applications done in this paper are all about object pushing. This thesis focuses on how to train the agent to learn pushing an object away as far as possible. Reinforcement Learning (RL), which is a type of Machine Learning (ML), is then utilized in this paper to train the agent to generate optimal actions. Deep Deterministic Policy Gradient (DDPG) and Hindsight Experience Replay (HER) are the two RL methods used in this thesis.
ContributorsLin, Steve (Author) / Ben Amor, Hani (Thesis advisor) / Redkar, Sangram (Committee member) / Zhang, Yu (Committee member) / Arizona State University (Publisher)
Created2023
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Description
Touch plays a vital role in maintaining human relationships through social andemotional communications. This research proposes a multi-modal haptic display capable of generating vibrotactile and thermal haptic signals individually and simultaneously. The main objective for creating this device is to explore the importance of touch in social communication, which is absent in traditional

Touch plays a vital role in maintaining human relationships through social andemotional communications. This research proposes a multi-modal haptic display capable of generating vibrotactile and thermal haptic signals individually and simultaneously. The main objective for creating this device is to explore the importance of touch in social communication, which is absent in traditional communication modes like a phone call or a video call. By studying how humans interpret haptically generated messages, this research aims to create a new communication channel for humans. This novel device will be worn on the user's forearm and has a broad scope of applications such as navigation, social interactions, notifications, health care, and education. The research methods include testing patterns in the vibro-thermal modality while noting its realizability and accuracy. Different patterns can be controlled and generated through an Android application connected to the proposed device via Bluetooth. Experimental results indicate that the patterns SINGLE TAP and HOLD/SQUEEZE were easily identifiable and more relatable to social interactions. In contrast, other patterns like UP-DOWN, DOWN-UP, LEFTRIGHT, LEFT-RIGHT, LEFT-DIAGONAL, and RIGHT-DIAGONAL were less identifiable and less relatable to social interactions. Finally, design modifications are required if complex social patterns are needed to be displayed on the forearm.
ContributorsGharat, Shubham Shriniwas (Author) / McDaniel, Troy (Thesis advisor) / Redkar, Sangram (Thesis advisor) / Zhang, Wenlong (Committee member) / Arizona State University (Publisher)
Created2021
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Description
Reinforcement Learning(RL) algorithms have made a remarkable contribution in the eld of robotics and training human-like agents. On the other hand, Evolutionary Algorithms(EA) are not well explored and promoted to use in the robotics field. However, they have an excellent potential to perform well. In thesis work, various RL learning

Reinforcement Learning(RL) algorithms have made a remarkable contribution in the eld of robotics and training human-like agents. On the other hand, Evolutionary Algorithms(EA) are not well explored and promoted to use in the robotics field. However, they have an excellent potential to perform well. In thesis work, various RL learning algorithms like Q-learning, Deep Deterministic Policy Gradient(DDPG), and Evolutionary Algorithms(EA) like Harmony Search Algorithm(HSA) are tested for a customized Penalty Kick Robot environment. The experiments are done with both discrete and continuous action space for a penalty kick agent. The main goal is to identify which algorithm suites best in which scenario. Furthermore, a goalkeeper agent is also introduced to block the ball from reaching the goal post using the multiagent learning algorithm.
ContributorsTrivedi, Maitry Ronakbhai (Author) / Amor, Heni Ben (Thesis advisor) / Redkar, Sangram (Thesis advisor) / Sugar, Thomas (Committee member) / Arizona State University (Publisher)
Created2021
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Description
In today’s modern world, industrial robots are utilized in hazardous working condi-tions across all industries, including the renewable energy industry. Robot control systems and sensors receive and transmit information and data obtained from the users. Over the last ten years, unmanned vehicles have developed into a subject of interest for a variety of

In today’s modern world, industrial robots are utilized in hazardous working condi-tions across all industries, including the renewable energy industry. Robot control systems and sensors receive and transmit information and data obtained from the users. Over the last ten years, unmanned vehicles have developed into a subject of interest for a variety of research institutions. Technology breakthroughs are redefin- ing disaster relief, search-and-rescue(SAR) and salvage operations’ for aerial robotic systems as well as terrestrial and marine ones. A team of collaborative robots is required for the challenging environments, such as space construction, and disaster relief. These robots will have to make trade-offs between mobility and capabilities owing to cost, power, and size constraints. Task execution in numerous areas may de- mand for robot collaboration in order to optimize team performance. An analysis of collaborative Unmanned Aerial Vehicle(UAV) and Unmanned Ground Vehicle(UGV) systems is one of the main components of this thesis. UAV/UGV collaborative frame- works and methods have been presented for reaching or monitoring moving human targets, a stated set-point for a mobile UGV robot to go to in order to approach a dynamic target, and actions to take by the UAVs when the mobile UGV robot is obstructed and cannot reach the target. This method encourages the target and robot to work together more closely. This is one of the most difficult issues in search and rescue operations since human targets are seldom found using just land robots or aerial robots. Finally, the purpose of this thesis is to suggest that the evaluation of the performance of a collaborative robot system may be accomplished by measuring the mobility of robots. Even though multi-robot coordination aids in SAR opera- tions, the findings of the study presented in this thesis conclude that the integration of various autonomous robotic systems in unstructured environments is difficult and that there is currently no unitary analytical model that can be used for this purpose.
ContributorsCherupally, SuryaKiran (Author) / Redkar, Sangram (Thesis advisor) / Nichols, Kevin (Committee member) / Subramanian, Susheel Kumar Cherangara (Committee member) / Arizona State University (Publisher)
Created2022
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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

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