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Research on human grasp typically involves the grasp of objects designed for the study of fingertip forces. Instrumented objects for such studies have often been designed for the simulation of functional tasks, such as feeding oneself, or for rigidity such that the objects do not deform when grasped. The goal of this thesis was to design a collapsible, instrumented object to study grasp of breakable objects. Such an object would enable experiments on human grip responses to unexpected finger-object events as well as anticipatory mechanisms once object fragility has been observed. The collapsible object was designed to be modular to allow for properties such as friction and breaking force to be altered. The instrumented object could be used to study both human and artificial grasp.
ContributorsTorrez, Troy (Author) / Santos, Veronica (Thesis director) / Santello, Marco (Committee member) / Artemiadis, Panagiotis (Committee member) / Barrett, The Honors College (Contributor)
Created2012-05
Description
This thesis focused on understanding how humans visually perceive swarm behavior through the use of swarm simulations and gaze tracking. The goal of this project was to determine visual patterns subjects display while observing and supervising a swarm as well as determine what swarm characteristics affect these patterns. As an ultimate goal, it was hoped that this research will contribute to optimizing human-swarm interaction for the design of human supervisory controllers for swarms. To achieve the stated goals, two investigations were conducted. First, subjects gaze was tracked while observing a simulated swarm as it moved across the screen. This swarm changed in size, disturbance level in the position of the agents, speed, and path curvature. Second, subjects were asked to play a supervisory role as they watched a swarm move across the screen toward targets. The subjects determined whether a collision would occur and with which target while their responses as well as their gaze was tracked. In the case of an observatory role, a model of human gaze was created. This was embodied in a second order model similar to that of a spring-mass-damper system. This model was similar across subjects and stable. In the case of a supervisory role, inherent weaknesses in human perception were found, such as the inability to predict future position of curved paths. These findings are discussed in depth within the thesis. Overall, the results presented suggest that understanding human perception of swarms offers a new approach to the problem of swarm control. The ability to adapt controls to the strengths and weaknesses could lead to great strides in the reduction of operators in the control of one UAV, resulting in a move towards one man operation of a swarm.
ContributorsWhitton, Elena Michelle (Author) / Artemiadis, Panagiotis (Thesis director) / Berman, Spring (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor)
Created2015-05
Description
The generation of walking motion is one of the most vital functions of the human body because it allows us to be mobile in our environment. Unfortunately, numerous individuals suffer from gait impairment as a result of debilitating conditions like stroke, resulting in a serious loss of mobility. Our understanding of human gait is limited by the amount of research we conduct in relation to human walking mechanisms and their characteristics. In order to better understand these characteristics and the systems involved in the generation of human gait, it is necessary to increase the depth and range of research pertaining to walking motion. Specifically, there has been a lack of investigation into a particular area of human gait research that could potentially yield interesting conclusions about gait rehabilitation, which is the effect of surface stiffness on human gait. In order to investigate this idea, a number of studies have been conducted using experimental devices that focus on changing surface stiffness; however, these systems lack certain functionality that would be useful in an experimental scenario. To solve this problem and to investigate the effect of surface stiffness further, a system has been developed called the Variable Stiffness Treadmill system (VST). This treadmill system is a unique investigative tool that allows for the active control of surface stiffness. What is novel about this system is its ability to change the stiffness of the surface quickly, accurately, during the gait cycle, and throughout a large range of possible stiffness values. This type of functionality in an experimental system has never been implemented and constitutes a tremendous opportunity for valuable gait research in regard to the influence of surface stiffness. In this work, the design, development, and implementation of the Variable Stiffness Treadmill system is presented and discussed along with preliminary experimentation. The results from characterization testing demonstrate highly accurate stiffness control and excellent response characteristics for specific configurations. Initial indications from human experimental trials in relation to quantifiable effects from surface stiffness variation using the Variable Stiffness Treadmill system are encouraging.
ContributorsBarkan, Andrew Robert (Author) / Artemiadis, Panagiotis (Thesis director) / Santello, Marco (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor)
Created2015-05
Description
This thesis focused on grasping tasks with the goal of investigating, analyzing, and quantifying human catching trends by way of a mathematical model. The aim of this project was to study human trends in a dynamic grasping task (catching a rolling ball), relate those discovered trends to kinematic characteristics of the object, and use this relation to control a robot hand in real time. As an ultimate goal, it was hoped that this research will aide in furthering the bio-inspiration in robot control methods. To achieve the above goal, firstly a tactile sensing glove was developed. This instrument allowed for in depth study of human reactionary grasping movements when worn by subjects during experimentation. This sensing glove system recorded force data from the palm and motion data from four fingers. From these data sets, temporal trends were established relating to when subjects initiated grasping during each trial. Moreover, optical tracking was implemented to study the kinematics of the moving object during human experiments and also to close the loop during the control of the robot hand. Ultimately, a mathematical bio-inspired model was created. This was embodied in a two-term decreasing power function which related the temporal trend of wait time to the ball initial acceleration. The wait time is defined as the time between when the experimental conductor releases the ball and when the subject begins to initiate grasping by closing their fingers, over a distance of four feet. The initial acceleration is the first acceleration value of the object due to the force provided when the conductor throws the object. The distance over which the ball was thrown was incorporated into the model. This is discussed in depth within the thesis. Overall, the results presented here show promise for bio-inspired control schemes in the successful application of robotic devices. This control methodology will ideally be developed to move robotic prosthesis past discrete tasks and into more complicated activities.
ContributorsCard, Dillon (Co-author) / Mincieli, Jennifer (Co-author) / Artemiadis, Panagiotis (Thesis director) / Santos, Veronica (Committee member) / Middleton, James (Committee member) / Barrett, The Honors College (Contributor) / School of Sustainability (Contributor) / Mechanical and Aerospace Engineering Program (Contributor) / W. P. Carey School of Business (Contributor)
Created2014-05
Description
The ideal function of an upper limb prosthesis is to replace the human hand and arm, but a gulf in functionality between prostheses and biological arms still exists, in large part due the absence of the sense of touch. Tactile sensing of the human hand comprises a key component of a wide variety of interactions with the external environment; visual feedback alone is not always sufficient for the recreation of nuanced tasks. It is hoped that the results of this study can contribute to the advancement of prosthetics with a tactile feedback loop with the ultimate goal of replacing biological function. A three-fingered robot hand equipped with tactile sensing fingertips was used to biomimetically grasp a ball in order haptically explore the environment for a ball-in-hole task. The sensorized fingertips were used to measure the vibration, pressure, and skin deformation experienced by each fingertip. Vibration and pressure sensed by the fingertips were good indicators of changes in discrete phases of the exploratory motion such as contact with the lip of a hole. The most informative tactile cue was the skin deformation of the fingers. Upon encountering the lip of the test surface, the lagging digit experienced compression in the fingertip and radial distal region of the digit. The middle digit experienced decompression of the middle region of the finger and the lagging digit showed compression towards the middle digit and decompression in the distal-ulnar region. Larger holes caused an increase in pressure experienced by the fingertips while changes in stroke speed showed no effect on tactile data. Larger coefficients of friction between the ball and the test surface led to an increase in pressure and skin deformation of the finger. Unlike most tactile sensing studies that focus on tactile stimuli generated by direct contact between a fingertip and the environment, this preliminary study focused on tactile stimuli generated when a grasped object interacts with the environment. Findings from this study could be used to design experiments for functionally similar activities of daily living, such as the haptic search for a keyhole via a grasped key.
ContributorsLoges, Shea Remegio (Author) / Santos, Veronica (Thesis director) / Artemiadis, Panagiotis (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor)
Created2014-05
Description
Walking ability is a complex process that is essential to humans, critical for performing a range of everyday tasks and enables a healthy, independent lifestyle. Human gait has evolved to be robust, adapting to a wide range of external stimuli, including variable walking surface compliance. Unfortunately, many people suffer from impaired gait as a result of conditions such as stroke. For these individuals, recovering their gait is a priority and a challenge. The ASU Variable Stiffness Treadmill (VST) is a device that is able to the change its surface compliance through its unique variable stiffness mechanism. By doing this, the VST can be used to investigate gait and has potential as a rehabilitation tool. The objective of this research is to design a variable damping mechanism for the VST, which addresses the need to control effective surface damping, the only form of mechanical impedance that the VST does not currently control. Thus, this project will contribute toward the development of the Variable Impedance Treadmill (VIT), which will encompass a wider range of variable surface compliance and enable all forms of impedance to be con- trolled for the first time. To achieve this, the final design of the mechanism will employ eddy current damping using several permanent magnets mounted to the treadmill and a large copper plate stationed on the ground. Variable damping is obtained by using lead screw mechanisms to remove magnets from acting on the copper plate, which effectively eliminates their effect on damping and changes the overall treadmill surface damping. Results from experimentation validate the mechanism's ability to provide variable damping to the VST. A model for effective surface damping is generated based on open-loop characterization experiments and is generalized for future experimental setups. Overall, this project progresses to the development of the VIT and has potential applications in walking surface simulation, gait investigation, and robot-assisted rehabilitation technology.
ContributorsFou, Linda Guo (Author) / Artemiadis, Panagiotis (Thesis director) / Lee, Hyunglae (Committee member) / Mechanical and Aerospace Engineering Program (Contributor, Contributor) / School of Mathematical and Statistical Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
In recent years, environment mapping has garnered significant interest in both industrial and academic settings as a viable means of generating comprehensive virtual models of the physical world. These maps are created using simultaneous localization and mapping (SLAM) algorithms that combine depth contours with visual imaging information to create rich, layered point clouds. Given the recent advances in virtual reality technology, these generated point clouds can be imported onto the Oculus Rift or similar headset for virtual reality implementation. This project deals with the robotic implementation of RGB-D SLAM algorithms on mobile ground robots to generate complete point clouds that can be processed off-line and imported into virtual reality engines for viewing in the Oculus Rift. This project uses a ground robot along with a Kinect sensor to collect RGB-D data of the surrounding environment to build point cloud maps using SLAM software. These point clouds are then exported as object or polygon files for post-processing in software engines such as Meshlab or Unity. The point clouds generated from the SLAM software can be viewed in the Oculus Rift as is. However, these maps are mainly empty space and can be further optimized for virtual viewing. Additional techniques such as meshing and texture meshing were implemented on the raw point cloud maps and tested on the Oculus Rift. The aim of this project was to increase the potential applications for virtual reality by taking a robotic mapping approach to virtual reality environment development. This project was successful in achieving its objective. The following report details the processes used in developing a remotely-controlled robotic platform that can scan its environment and generate viable point cloud maps. These maps are then processed off line and ported into virtual reality software for viewing through the Oculus Rift.
ContributorsUdupa, Shreya (Author) / Artemiadis, Panagiotis (Thesis director) / Chickamenahalli, Shamala (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Economics Program in CLAS (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
This study presents quantification of ankle stability as affected by environmental conditions in two degrees of freedom (DOF) with three distinct analysis techniques. Additionally, this study presents gender-specific trends for comparison. Intuitively, ankle stability decreased in less stable environments with a negative simulated stiffness. Female subjects generally suffered a greater loss of stability in moderately and highly unstable environments. Both gender groups exhibited greater stability in the sagittal plane than the frontal plane across the entire range of simulated stiffness's. Outcomes of this study are useful in the design of controllers for lower extremity physically-interactive robotics, understanding situations in which the ankle is likely to lose stability, and understanding the strengths and weaknesses of unique analysis techniques.
ContributorsHanzlick, Harrison Patrick (Author) / Lee, Hyunglae (Thesis director) / Artemiadis, Panagiotis (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / W. P. Carey School of Business (Contributor) / Barrett, The Honors College (Contributor)
Created2017-12
Description
For the past two decades, advanced Limb Gait Simulators and Exoskeletons have been developed to improve walking rehabilitation. A Limb Gait Simulator is used to analyze the human step cycle and/or assist a user walking on a treadmill. Most modern limb gait simulators, such as ALEX, have proven themselves effective and reliable through their usage of motors, springs, cables, elastics, pneumatics and reaction loads. These mechanisms apply internal forces and reaction loads to the body. On the other hand, external forces are those caused by an external agent outside the system such as air, water, or magnets. A design for an exoskeleton using external forces has seldom been attempted by researchers. This thesis project focuses on the development of a Limb Gait Simulator based on a Pure External Force and has proven its effectiveness in generating torque on the human leg. The external force is generated through air propulsion using an Electric Ducted Fan (EDF) motor. Such a motor is typically used for remote control airplanes, but their applications can go beyond this. The objective of this research is to generate torque on the human leg through the control of the EDF engines thrust and the opening/closing of the reverse thruster flaps. This device qualifies as "assist as needed"; the user is entirely in control of how much assistance he or she may want. Static thrust values for the EDF engine are recorded using a thrust test stand. The product of the thrust (N) and the distance on the thigh (m) is the resulting torque. With the motor running at maximum RPM, the highest torque value reached was that of 3.93 (Nm). The motor EDF motor is powered by a 6S 5000 mAh LiPo battery. This torque value could be increased with the usage of a second battery connected in series, but this comes at a price. The designed limb gait simulator demonstrates that external forces, such as air, could have potential in the development of future rehabilitation devices.
ContributorsToulouse, Tanguy Nathan (Author) / Sugar, Thomas (Thesis director) / Artemiadis, Panagiotis (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
The quality of life of many people is lowered by impediments to walking ability caused by neurological conditions such as strokes. Since the ankle joint plays an important role in locomotion, it is a common subject of study in rehabilitation research. Robotic devices such as active ankle-foot orthoses and powered exoskeletons have the potential to be used directly in physical therapy or indirectly in research pursuing more effective rehabilitation methods. This paper presents the LiTREAD, a lightweight three degree-of-freedom robotic exoskeletal ankle device. This novel robotic system is designed to be worn on a user's leg and actuate the foot position during treadmill studies. The robot's sagittal plane actuation is complemented by passive virtual axis systems in the frontal and transverse planes. Together, these degrees of freedom allow the device to approximate the full range of motion of the ankle. The virtual axis mechanisms feature locking configurations that will allow the effect of these degrees of freedom on gait dynamics to be studied. Based on a kinematic analysis of the robot's actuation and geometry, it is expected to meet and exceed its torque and speed targets, respectively. The device will fit either leg of a range of subject sizes, and is expected to weigh just 1.3 kg (2.9 lb.). These features and characteristics are designed to minimize the robot's interference with the natural walking motion. Pending validation studies confirming that all design criteria have been met, the LiTREAD prototype that has been constructed will be utilized in various experiments investigating properties of the ankle such as its mechanical impedance. It is hoped that the LiTREAD will yield valuable data that will expand our knowledge of the ankle and aid in the design of future lower-extremity devices.
ContributorsCook, Andrew James Henry (Author) / Lee, Hyunglae (Thesis director) / Artemiadis, Panagiotis (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12