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Moses, Kenneth C.A Durable Terrestrial Drive Train for a Small Air Vehicle
Master of Sciences (Engineering), Case Western Reserve University, 2010, EMC - Mechanical Engineering
Weight, aerodynamic profile, and strength are considered in the design of a terrestrial drive train for a small air vehicle. Several drive trains were developed and their performance characteristics compared in order to show a progression in their designs. Each iteration contained minor improvements, approaching the goal of a durable terrestrial drive train for a small air vehicle. These drive trains were analyzed in the Case Western Reserve University low-speed wind tunnel for their influence on the performance of the aircraft. The change in lift produced by the aircraft’s airfoil ranges from -1.0% to -4.5%. The drive trains were also tested for their ability to withstand the shock and reduce the impact of landing. Spring steel wire wheel-legs are found to reduce the peak deceleration by 15.8%. The results identify one drive train that meets the performance goals and is suitable for general use in this scale application.

Committee:

Roger Quinn, PhD (Committee Chair); Yasuhiro Kamotani, PhD (Committee Member); Joseph Prahl, PhD (Committee Member)

Subjects:

Engineering; Fluid Dynamics; Mechanical Engineering; Robots; Technology

Keywords:

Micro Air Vehicle; MAV; hybrid vehicle; drive train; terrestrial locomotion; aerial locomotion; wind tunnel; impact test; aircraft design; aerodynamics;

Smith, Lauren MelissaThe Tri-Wheel: A Novel Robot Locomotion Concept Meeting the Need for Increased Speed and Climbing Capability
Master of Sciences, Case Western Reserve University, 2015, EMC - Mechanical Engineering
A need has been expressed for a robot locomotion concept that incorporates both efficient, rapid motion on smooth surfaces as well as the capacity to traverse a variety of challenging terrain obstacles, including but not limited to: stairs, rubble, and other environmental impediments. Currently, this dual capability has not been optimized successfully for existing locomotion concepts. This research seeks to meet this need with a novel mobility concept called the Tri-Wheel and chronicles its theoretical conception, design, and preliminary testing. An in-depth discussion of the design process and determination of derived requirements is first presented to substantiate the final configuration. The Tri-Wheel is then manufactured and installed on an existing robot chassis for testing, ultimately proving the concept successful by meeting the stated research objectives.

Committee:

Roger Quinn (Committee Chair); Paul Barnhart (Committee Member); Joseph Mansour (Committee Member)

Subjects:

Engineering; Mechanical Engineering; Robotics; Robots

Keywords:

robot locomotion; wheels; gearing; first responder; novel locomotion platform; wheel-leg hybrid; Tri-Wheel

Long, Leroy L.An Experiment in Human Locomotion: Energetic Cost and Energy-Optimal Gait Choice
Master of Science, The Ohio State University, 2011, Mechanical Engineering
This thesis experimentally and theoretically explores the hypothesis that humans move in a way that minimizes the metabolic cost (energy usage) to travel a given distance on foot. Humans are at least approximately energy efficient (Borelli, 1680; Alexander R. M., 1989; 2003; Srinivasan & Ruina, 2006). We have performed an experiment to test this hypothesis: the walking and running behavior of humans on a level walkway (i.e. racetrack, building corridor, sidewalk, or pavement). Theoretical calculations based on energy minimization for a typical human predict that when asked to travel a given distance in a prescribed amount of time, humans will: a)‘Walk’ the entire distance when given a large amount of time. b)‘Run’ the entire distance when given a short amount of time. c)Use a mixture of both walking and running at intermediate intervals of time. We performed human subject experiments to test the above predictions. In the experiment, participants are asked to choose a pattern of movement (walking/running) to travel a particular distance on a sidewalk in a specified amount of time. Each subject is equipped with a GPS device, a heart rate monitor and foot pod to measure speed, heart rate and step frequency respectively. The gathered data and results from this experiment suggest that the experiments indeed agree with qualitative theoretical predictions for a typical human providing further evidence for energy optimality in locomotion.

Committee:

Manoj Srinivasan (Advisor); Carlos Castro (Committee Member)

Subjects:

Biomechanics

Keywords:

locomotion; human locomotion; movement; walking; running; gait; gait choice

Aiello, Brett R.Correlation of bone strain and muscle function in the hindlimb of the river cooter turtle (Pseudemys concinna)
Master of Science in Biological Sciences, Youngstown State University, 2012, Department of Biological Sciences
Limb muscles have important roles during locomotion, such as counteracting ground reaction forces (GRF) and generating propulsive mechanical work and power. Depending on the magnitude and direction of the GRF or the performance demands of locomotion, limb muscles may produce high forces that impose substantial loads on limb bones. While bone loading has been studied over a relatively broad phylogenetic and functional range of tetrapod lineages, much less is known about how muscle contractile function directly influences patterns and magnitudes of bone loading. To better understand mechanisms of limb bone loading in terrestrial locomotion, we correlated direct measurements of in vivo bone strain with muscle strain (via sonomicrometry) and EMG activation in a major hip extensor/knee flexor muscle (m. flexor tibialis internus) of river cooter turtles (Pseudemys concinna) during treadmill walking. EMG recordings indicate activity prior to footfall that continues through approximately 50% of the stance phase. The muscle fascicles reach their maximum length just after footfall and actively shorten to their minimum length at 35% of stance. At the time of peak bone strains (both principal and axial), the muscle fascicles are active, but are lengthening as the knee joint begins to extend. On average, the time difference between peak bone strain and muscle strain was 5% of stance. Thus, due to the coincidence between bone strains muscle shortening, bone loading patterns can be correlated directly with the action of limb muscles, refining models of femoral loading derived from force platform studies, and indicating a significant role for FTI in femoral loading in turtles that may explain differences in safety factor estimates between force plate and in vivo strain analyses.

Committee:

Michael T. Butcher, PhD (Advisor); Mark D. Womble, PhD (Committee Member); Robert E. Leipheimer, Ph.D. (Committee Member); Richard W. Blob, Ph.D. (Committee Member)

Subjects:

Anatomy and Physiology; Biology; Biomechanics; Zoology

Keywords:

muscle contractile activity via sonomicrometry and EMG; biomechanics of locomotion; bone strain; turtle

Pesek, Michelle JThe Effects of a Short-term Backwards Running Program on Aerobic Capacity, Equilibrium, and Physiologic Novelty of Task
Master of Science in Exercise and Health Studies, Miami University, 2013, Exercise and Health Studies
Backward running (BR) is commonly used in sport conditioning, for motor learning and neurological purposes, and even more commonly in physical rehabilitation. The current study investigated the effects of a three week backwards running program on cardiorespiratory fitness, equilibrium, and physiologic novelty of task. Eight (n = 8) male and female college students participated in the study. Subjects were randomly assigned to either a backwards running group (BG) (n = 4) or a no backward running group (NBG) (n = 4). All subjects underwent both forward and backward maximum oxygen consumption testing (V02 max) with lactate readings and balance testing on a force plate in week 0 (pre-intervention) and week 5 (post intervention). Additionally, within the BG, average daily heart rates and speed of sessions were recorded daily during the backwards program to assess physiologic novelty of task. No significant improvements were found in cardiorespiratory fitness as evident in both backward and forward V02 max tests following the three week backward running program. Overall, regardless of the time tested, subjects in the NBG exhibited more time farther away from their mean center of pressure when swaying in the medial-lateral (M-L) axis while standing on the right leg only. All subjects showed a decrease in equilibrium from pre to post tests when standing on the left leg only in the M-L axis. Overall, trends were seen for increased cardiorespiratory fitness and equilibrium with backwards training. Furthermore, it is seen that constant adjustment is needed with backwards programs as it is proposed novelty begins to decrease in as little as one week.

Committee:

Mark Walsh, PhD (Advisor); Ronald Cox, PhD (Committee Member); Rose Marie Ward, PhD (Committee Member)

Subjects:

Health Sciences; Kinesiology

Keywords:

backwards running; VO2 max; balance; running; novelty; equilibrium; cardiorespiratory; sway; backwards locomotion

Jorgensen, RyanThree-dimensional trajectories affect the epaxial muscle activity of arboreal snakes crossing gaps
MS, University of Cincinnati, 2017, Arts and Sciences: Biological Sciences
Arboreal habitats have considerable three-dimensional complexity and sizable gaps between branches. Many species of snakes are arboreal and cross large gaps in different directions, but the muscle activity used to do this is unknown. Hence, we used brown tree snakes (Boiga irregularis) bridging gaps to test how the three-dimensional trajectory affected muscle activity and whether these motor patterns differed from those of terrestrial snake locomotion. We used five trajectories: pitch angles of 90, 0 and -90 deg (downhill) when yaw = 0 and 90 deg yaw angles to the left and right when pitch = 0 deg. We recorded movement and EMGs from the three largest epaxial muscles, which from dorsal to ventral are the semispinalis-spinalis (SSP), longissimus dorsi (LD), and iliocostalis (IL). Overall, the SSP had extensive bilateral activity, which resembled the motor pattern during the dorsiflexion of sidewinding snakes. Unlike any previously described terrestrial snake locomotion, bilateral activity of the LD and IL was also common during gap bridging. The largest amounts of muscle activity usually occurred for horizontal gaps, and muscle activity decreased markedly as soon as the snake’s head touched the far edge of the gap. Snakes had the least amount of muscle activity for pitch = -90 deg. While turning sideways, muscles on the convex side had less activity when turning compared to the concave side. Hence, the orientation relative to gravity profoundly affected muscle activity during gap bridging, and these complex three-dimensional movements involved several previously undescribed variants of axial motor pattern.

Committee:

Bruce Jayne, Ph.D. (Committee Chair); Elke Buschbeck, Ph.D. (Committee Member); Daniel Wagenaar, Ph.D. (Committee Member)

Subjects:

Biomechanics

Keywords:

Boiga irregularis;cantilever;arboreal;electromyography;locomotion

Zheng, Yuan-FangModeling, control and simulation of three-dimensional robotic systems with applications to biped locomotion/
Doctor of Philosophy, The Ohio State University, 1984, Graduate School

Committee:

Not Provided (Other)

Subjects:

Physics

Keywords:

Locomotion--Mathematical models;Robotics

Kwak, Se-HungA computer simulation study of a free gait motion coordination algorithm for rough-terrain locomotion by a hexapod walking machine /
Doctor of Philosophy, The Ohio State University, 1986, Graduate School

Committee:

Not Provided (Other)

Subjects:

Engineering

Keywords:

Robots;Locomotion;Computer simulation

Cheng, In-ShengComputer-television analysis of biped locomotion /
Doctor of Philosophy, The Ohio State University, 1974, Graduate School

Committee:

Not Provided (Other)

Subjects:

Engineering

Keywords:

Human locomotion

Hansen, Christopher NelsonREMOTE DISRUPTION OF FUNCTION, PLASTICITY, AND LEARNING IN LOCOMOTOR NETWORKS AFTER SPINAL CORD INJURY
Doctor of Philosophy, The Ohio State University, 2013, Neuroscience Graduate Studies Program
Spinal cord injury (SCI) creates a diverse range of functional outcomes. Impaired locomotion may be the most noticeable and debilitating consequence. Locomotor patterns result from a dynamic interaction between sensory and motor systems in the lumbar enlargement of the spinal cord. After SCI, conflicting cellular and molecular processes initiate along the neuroaxis that may secondarily jeopardize function, plasticity, and learning within locomotor networks. Thus, we used a standardized thoracic contusion to replicate human pathology and identified behavioral, physiological, cellular, and molecular effects in rat and mouse models. Specifically, our goal was to identify kinematic and neuromotor changes during locomotion, evaluate the role of axonal sparing on remote spinal learning, and identify mechanisms of neuroinflammation in the lumbar enlargement that may prevent locomotor plasticity after SCI. Eccentric muscle actions require precise segmental integration of sensory and motor signals. Eccentric motor control is predominant during the yield (E2) phase of locomotion. To identify kinematic and neuromotor changes in E2, we used a mild SCI that allows almost complete functional recovery. Remaining deficits included a caudal shift in locomotor subphases that accompanied a marked reduction in eccentric angular excursions and intralimb coordination. Underlying these metrics, we found distinct bursting impairments in the semitendinosus. Phasic impairments during the eccentric activation of the semitendinosus improved over time and predicted the extent of recovery. Our findings suggest that maladaptive integration of descending and afferent signals limit central pattern generator-directed locomotion after SCI. Axonal sparing after SCI facilitates plasticity rostral and caudal to the lesion. To evaluate the role of axonal sparing on remote lumbar plasticity, we examined learning in isolated lumbar segments early (7d) and late (42d) after SCI. A proof of principle design compared rats that recovered with or without sparing. Early after SCI, learning was impaired regardless of sparing. Alternatively, axonal sparing during recovery allowed near-normal learning late after SCI. To determine if eccentric task-specific training differentially regulates spinal learning, we delivered flat or downhill treadmill training late after recovery from incomplete SCI (34-41d). Downhill treadmill training improved recovery and central learning. This work identifies a time dependent interaction between spared axonal systems and task-specific plasticity in locomotor networks. To determine if remote mechanisms of neuroinflammation impede locomotor plasticity, we conducted a series of experiments in wild type (WT) and genetically engineered (KO) mice. Within 24h in WT mice, resident microglia displayed an inflammatory phenotype alongside increased expression of pro-gelatinase, MMP-3. By 7 and 9d, MMP-9 and TNFa reached significant elevations alongside persistent activation of resident microglia. In MMP-9 null (KO) mice, inflammatory signaling was restored to homeostatic levels. Finally, we examined recovery after early (2-9d) or late (35-42d) treadmill training delivered in WT and MMP-9 KO mice. We found that early training resulted in robust locomotor recovery in MMP-9 KO mice that was retained 4-weeks after the intervention ended. Late training failed to promote recovery in either groups. With these findings, we identified a robust period of locomotor plasticity early after thoracic SCI that is blunted by remote neuroinflammation in locomotor networks.

Committee:

D. Michele Basso, PT, EdD (Advisor)

Subjects:

Neurosciences

Keywords:

Spinal Cord Injury, Locomotion, Neuroinflammation

Horner, Angela M.Crouched Locomotion in Small Mammals: The Effects of Habitat and Aging
Doctor of Philosophy (PhD), Ohio University, 2010, Biological Sciences (Arts and Sciences)
This dissertation project seeks to elucidate the biomechanics of crouched locomotion in small mammals using natural, ecologically relevant perturbations — aging and substrate. The second chapter of this dissertation examines locomotion and sarcopenia in the aging rat, arguably one of most well-studied model vertebrates. Rather than focusing on rats as human models, however, this paper addresses some of the specific challenges encountered by small, crouched animals, the importance of incorporating whole-animal performance measures, and finally how aging might be used as a model experimental technique. The third and fourth chapters of this study address four aspects of tunnel (“subterranean”) locomotion — posture, gait, COM mechanics and energetic cost of locomotion — with comparison to epigean (unconstrained, or overground) conditions. These data are then synthesized to broadly illustrate the performance consequences of tunnel locomotion in small mammals, with particular focus on how mammals may conserve metabolic energy via mechanical and anatomical adaptations. The focus of the third chapter is the locomotion of the domestic ferret(Mustela putorious furo) moving on a force trackway. For this, gaits, posture and center-of-mass mechanics were used as metrics of performance. The fourth chapter is an investigation of the energetic cost of moving in tunnels, with reference to the data from the force trackway study. As an additional test of putative semi-fossorial adaptations, two related rodent species (the semi-fossorial degu, Octodon degus, and the generalist guinea pig, Cavia porcellus) were also measured in both experimental conditions to assess what energetic benefits or costs might be associated with semi-fossoriality.

Committee:

Audrone Biknevicius, PhD (Advisor); Nancy Stevens, PhD (Committee Member); Steve Reilly, PhD (Committee Member); Willem Roosenburg, PhD (Committee Member); Dan Hembree, PhD (Committee Member)

Subjects:

Zoology

Keywords:

animal locomotion; biomechanics; mammal; tunnel; ferret; mechanics; rat; metabolics; energetics; aging

Hyams, Sara E.Arboreal Habitat Structure Affects Locomotor Speed and Path Choice of White-footed Mice (Peromyscus leucopus)
MS, University of Cincinnati, 2010, Arts and Sciences : Biological Sciences
Arboreal habitats pose several challenges for locomotion resulting from narrow cylindrical surfaces, steep inclines, and branches that obstruct straight paths. I determined whether different diameters, inclines, or complexity of branches affected speed of movement and path choice for a semi-arboreal rodent (Peromyscus leucopus). We videotaped laboratory trials of locomotor performance of mice running on cylinders with diameters of 10, 16, 28, 54, and 116 mm, oriented at inclines of 0° and 45° (uphill and downhill), and a subset of diameters horizontally oriented that had secondary branches (pegs) every 10 or 20 cm. For similar branch diameters the speeds of mice were usually faster when running horizontally rather than on inclines, and pegs decreased running speed compared to unobstructed surfaces. When pegs were present, the frequency and duration of pauses increased, speed decreased with decreased distance between pegs, and larger diameters enhanced speeds by reducing the need of mice to use a convoluted trajectory to avoid the pegs. The difficulties of maintaining balance and avoiding toppling seem likely to have caused much of the decrease in speed and increased amounts of pausing. Thus, branch diameter, incline, and the presence of and spacing of secondary branches often had widespread and significant interactive effects on locomotor performance, and additional experiments revealed some of these factors significantly influenced the routes chosen by mice.

Committee:

Guy Cameron, PhD (Committee Chair); Bruce Jayne, PhD (Committee Member); Kenneth Petren, PhD (Committee Member)

Subjects:

Ecology

Keywords:

Peromyscus leucopus;arboreal;habitat structure;performance;locomotion;route choice

Yang, TaoControl of aperiodic walking and the energetic effects of parallel joint compliance of planar bipedal robots
Doctor of Philosophy, The Ohio State University, 2007, Mechanical Engineering
In this dissertation, two problems related to bipedal robot walking are presented. The first problem is the influence of parallel knee joint compliance on the average power cost of walking in an underactuated planar bipedal robot, ERNIE. The second problem is the design of walking controllers that induce aperiodic bipedal robot walking. It has been found that compliance plays important roles in walking and running in animals. Compliance has been used in robotic bipedal machines to improve energetic efficiency or reduce the peak power demand on the robot's actuators. This dissertation presents numerical and experimental studies of the influence of parallel knee joint compliance on the average power cost of walking in an underactuated planar bipedal robot, ERNIE. Four scenarios were studied: one without springs and three with springs of different stiffnesses and preloads. Optimal gaits in terms of average power cost for various speeds were designed for each scenario. It was found that for low-speed walking, soft springs are helpful to reduce power cost, while stiffer springs increase power cost. For high-speed walking, it was found that both soft and stiff springs reduce the average power cost of walking, but stiffer springs reduce the cost more than do softer springs. The second problem addressed in this dissertation is aperiodic walking controller design. The ability to walk stably in varying environments or with different tasks, such as stepping over stones, is of great interest in bipedal walking. In these scenarios, the walking is not periodic. This dissertation presents a new definition of stable walking that is not necessarily periodic for a class of biped robots. The inspiration for the definition is the commonly-held notion of stable walking: the biped does not fall. To make the definition useful, an algorithm is given to verify if a given controller induces stable walking. Also given is a framework to synthesize controllers that induce stable walking. The results are illustrated with numerical simulation and experiments. This dissertation also presents details of a modeling procedure for the experimental bipedal robot, ERNIE, and explores the possibility to apply iterative learning control to bipedal walking.

Committee:

Eric Westervelt (Advisor)

Subjects:

Engineering, Mechanical

Keywords:

Bipedal robots; Locomotion; Control; Aperiodic walking; Compliance

Hanson, Martin GartzTHE EMBRYONIC NEURAL CIRCUIT: MECHANISM AND INFLUENCE OF SPONTANEOUS RHYTHMIC ACTIVITY IN EARLY SPINAL CORD DEVELOPMENT
Doctor of Philosophy, Case Western Reserve University, 2004, Neurosciences
Over the last several decades, a general consensus has emerged that molecular mechanisms are required for proper axon pathfinding and initial circuit formation while activity dependent mechanisms primarily regulate the synaptic refinement important for proper connectivity of the circuit. Shortly after motoneurons are born, they begin to extend axons into the periphery and make early pathfinding decisions. Experiments described within this thesis demonstrate that spontaneous rhythmic bursting episodes of electrical activity as well as spontaneous unit activity could be recorded from these extending axons. Therefore, this spontaneous rhythmic activity during initial outgrowth might play an important role in early axonal decisions. In order to test this hypothesis, it was first essential to characterize the cellular mechanisms required for the initiation and propagation of these episodes. Experiments further demonstrated that the motoneurons, via cholinergic transmission, are essential for the production of this early spontaneous activity but that GABA and glycine acting in an excitatory manner also contribute. With this detailed characterization of the circuit that generates this activity, it was possible to pharmacologically alter the frequency of the spontaneous rhythmic episodes in ovo during precise stages of development while maintaining spontaneous unit activity. Altering the frequency of rhythmic bursting activity during early pathfinding at the nerve plexus not only induced motor axon pathfinding errors, but also altered the expression of EphA4 and polysialic acid on NCAM (PSA), molecules known to be required for early pathfinding. Thus, this work illustrates that both early motor axon pathfinding and the expression of specific guidance molecules is dependent on spontaneous rhythmic episodes of activity from the spinal cord.

Committee:

Lynn Landmesser (Advisor)

Subjects:

Biology, Neuroscience

Keywords:

motoneurons; locomotion; guidance; mouse; chick; spontaneous; circuits; cholinergic; glycine; GABA; PSA; EphA4

Chao, Ching-ShuReal-time multiprocessor control of a hexapod vehicle /
Doctor of Philosophy, The Ohio State University, 1979, Graduate School

Committee:

Not Provided (Other)

Subjects:

Engineering

Keywords:

Multiprocessors;Locomotion

Meglan, Dwight AlanEnhanced analysis of human locomotion /
Doctor of Philosophy, The Ohio State University, 1991, Graduate School

Committee:

Not Provided (Other)

Subjects:

Engineering

Keywords:

Human locomotion

Jaswa, Vijay ChinubhaiAn experimental study of real-time computer control of a hexapod vehicle /
Doctor of Philosophy, The Ohio State University, 1978, Graduate School

Committee:

Not Provided (Other)

Subjects:

Engineering

Keywords:

Automation;Locomotion

Pai, Ammembal LakshmanaStability and control of legged locomotion systems /
Doctor of Philosophy, The Ohio State University, 1971, Graduate School

Committee:

Not Provided (Other)

Subjects:

Engineering

Keywords:

Locomotion

Sun, Shu-ShenA Theoretical study of gaits for legged locomotion systems /
Doctor of Philosophy, The Ohio State University, 1974, Graduate School

Committee:

Not Provided (Other)

Subjects:

Engineering

Keywords:

Locomotion

Liu, YipingA Dual-SLIP Model For Dynamic Walking In A Humanoid Over Uneven Terrain
Doctor of Philosophy, The Ohio State University, 2015, Electrical and Computer Engineering
Control of 3D dynamic walking in bipedal legged machines or humanoid robots remains a challenging problem. To address the complexity brought by the high degrees of freedom (DoFs) in the target system, very often a simple template model is used as an intermediate bridge. A template model is typically much simpler, but can still capture the key characteristics of the dynamics of a particular motion. Usually, a control policy is first developed to regulate the behavior of the template model, then resultant trajectories of the template model are mapped to the whole-body motion of the more complex robot through some optimization-based task-space control strategies. Currently, the most widely used walking template is the Linear Inverted Pendulum Model (LIPM). It has gained popularity due to its simple linearized dynamics, and walking controllers based on the LIPM have had some success. However, the resultant walking gaits from the LIPM miss some of the dynamics that can lead to more efficient gaits such as those in a human. This is due in part to its constant height assumption and the lack of a double support phase. Recently, an alternative walking template called the Dual-SLIP (spring-loaded inverted pendulum) model (or Bipedal SLIP model) has been proposed. This model has its roots in biomechanics studies. With leg compliance it can faithfully reproduce the ground reaction force (GRF) patterns and center of mass (CoM) vertical oscillations observed during human walking. Also its bipedal nature allows it to seamlessly integrate the double support phase during walking. It even has the potential to become a general template that can model both walking and running. Some analyses and control strategies have been developed around this new template. However, almost all the studies are limited to the 2D version of this model. The behavior of the 3D Dual-SLIP model is much more difficult to regulate than its 2D counterpart. And the problem is accentuated when walking over uneven terrain, especially with step height uncertainty. However, to actually use this model as a walking template for a humanoid, the 3D extension is necessary. With such motivation, this thesis is dedicated to develop a dynamic walking controller for a humanoid based on the 3D Dual-SLIP model while traversing uneven terrain. The development is divided into three stages. In the first stage the focus is on 3D walking over flat ground. A new optimization-based approach is proposed to find periodic walking gaits. Through analysis of the dynamics of the 3D Dual-SLIP model, a novel symmetry condition has been identified that is used to greatly simplify the optimization process. It has also been found during the study that the regular conservative 3D Dual-SLIP model is not capable of generating forward walking at speeds faster than 1.4 m/s (assuming a leg length of 1 m). To address this limitation, a variant of the regular Dual-SLIP model, the actuated Dual-SLIP, is introduced to address high-speed walking. With bio-inspired leg actuation, the model can walk up to 2 m/s, which is at the top end of the range of human walking speeds. Since the periodic gaits of the 3D Dual-SLIP model are found to not be self-stable, a discrete-time infinite-horizon LQR controller has been developed to regulate the state of the model. Through this approach, the controller can recover from significant disturbances by automatically adapting footstep positions during walking. In the second stage, the development of the first stage is extended to known uneven terrain, which is the first time the 3D Dual-SLIP model (with leg actuation) has been used to generate dynamic walking gaits over uneven terrain. Since the symmetry condition can no longer be used to aid in the search for periodic gaits over uneven terrain, an improved CoM trajectory and footstep position generation method is developed based on multiple-shooting optimization that is applicable to both flat ground and uneven terrain (with elevation changes up to +/-10% of leg length per step). The resultant gait for flat ground is consistent with that found with the simpler approach of the first stage. The gait over uneven terrain also shows a rich set of human-like characteristics as observed in biomechanics studies. Finally, the work in the second stage is further extended to address a more challenging problem: 3D "blind'' walking with no knowledge of terrain information. Through the expansion of the techniques introduced in the second stage, swing leg retraction and extension strategies (towards the end of the swing phase) for the 3D actuated Dual-SLIP model are developed that allow it to automatically adapt its walking gait over unforeseen terrain height changes up to +/-5% of leg length while maintaining full forward speed. The resultant CoM trajectories and footstep positions of the 3D Dual-SLIP model from the development in all three stages are used to successfully orchestrate dynamic walking motion in real-world humanoid robot models in simulation through a task-space control framework. This is the first demonstration of Dual-SLIP based dynamic walking in a humanoid.

Committee:

David Orin (Advisor)

Subjects:

Robotics

Keywords:

humanoid and bipedal locomotion

Stark, Alyssa Yeager The Effect of Water on the Gecko Adhesive System
Doctor of Philosophy, University of Akron, 2014, Integrated Bioscience
The gecko adhesive system is a dry, reversible adhesive that is virtually surface-insensitive due to the utilization of intermolecular van der Waals forces. Remarkably, although detailed models of the adhesive mechanism exist and hundreds of gecko-inspired synthetics have been fabricated, our ability to fully replicate the system still falls short. One reason for this is our limited understanding of how the system performs in natural environments. To begin to resolve this I focused on one particular environmental parameter, water. Although thin layers of water can disrupt van der Waals forces, I hypothesized that geckos are able to retain or regain adhesive function on wet surfaces. I was motivated to investigate this hypothesis because many species of gecko are native to the tropics, a climate where we expect surface water to be prevalent, thus it is likely geckos have some mechanism to overcome the challenges associated with surface water and wetting. Despite the challenge water should pose to adhesion, I found that when tested on hydrophobic substrates geckos cling equally well in air and water. Conversely, on wet hydrophilic substrates geckos cannot support their body weight. Investigating these results further, I found that the superhydrophobic nature of the adhesive toe pads allows geckos to form an air bubble around their foot, which when pressed into contact with a hydrophobic substrate likely removes water from the adhesive interface. When the toe pads are no longer superhydrophobic however, geckos cannot support their body weight and fall from substrates. In order to regain adhesion geckos only need to take about ten steps on a dry substrate to self-dry their toe pads. Finally, when measuring a dynamic component of adhesion, running, we found that geckos are able to maintain speed on misted hydrophobic and hydrophilic substrates, contrary to what we would predict based on static shear adhesion measurements. In conclusion, my research provides a detailed investigation of how water affects the gecko adhesive system and has applications for synthetic design of adhesives which retain or regain function in water and further motivates the study of this remarkable system in a more environmentally relevant context.

Committee:

Peter Niewiarowski, Dr. (Advisor); Ali Dhinojwala, Dr. (Advisor); Todd Blackledge, Dr. (Committee Member); Matthew Shawkey, Dr. (Committee Member); Jutta Luettmer-Strathmann, Dr. (Committee Member)

Subjects:

Animals; Biology; Biomechanics; Biophysics; Ecology; Materials Science; Morphology; Organismal Biology; Polymers; Zoology

Keywords:

gecko; adhesion; water; superhydrophobic; biomimicry; van der Waals; wetting; locomotion; friction; contact angle; self-cleaning; morphology; performance; behavior; ecology

Copploe, Joseph V.In Vivo Strains in the Femur of the Nine-Banded Armadillo (Dasypus novemcinctus)
Master of Science in Biological Sciences, Youngstown State University, 2014, Department of Biological Sciences
Understanding of the interplay between bone loading patterns and bone material properties in mammals has been based primarily on evidence from upright eutherians, which show limb bones that are loaded predominantly in anteroposterior (AP) bending with minimal torsion. However, loading patterns from the femora of marsupial opossums using crouched limb posture, show appreciable torsion while the bone experiences mediolateral (ML) bending. These data indicated greater locomotor loading diversity than was previously recognized, and suggested the possibility that ancestral loading patterns found in sprawling reptiles might have been retained among basal mammals. To further test this hypothesis, in vivo locomotor strains were recorded from the femur of the nine-banded armadillo (Dasypus novemcinctus). Orientations of principal strains and magnitudes of shear strains indicate that their femora are exposed to a limited amount of torsion, while loading is dominated by ML bending that places the medial aspect of the femur in compression and the lateral aspect in tension. This orientation of bending is similar to that found in opossums, but planar strain analyses indicate much more of the armadillo femur experiences tension during bending, potentially due to the actions of large muscles attached to the robust third trochanter (T3). Comparisons of peak locomotor loads to evaluations of femoral mechanical properties lead to estimates of limb bone safety factors between 2.3--5.0 in bending, similar to other eutherians, but lower than opossums and most sprawling taxa. Thus, femoral loading patterns in armadillos show a mixture of similarities to both opossums (ML bending) and eutherians (limited torsion and low safety factors), along with unique features (high axial tension) that likely relate to their distinctive hindlimb anatomy.

Committee:

Michael Butcher, PhD (Advisor); Mark Womble, PhD (Committee Member); Thomas Diggins, PhD (Committee Member)

Subjects:

Biomechanics

Keywords:

Bone; Bending; Torsion; Safety factor; Locomotion; Mammal; Stress

HIGHAM, TIMOTHY EDWARDEFFECTS OF INCLINE ON CHAMELEON LOCOMOTION: IN VIVO MUSCLE ACTIVITY AND THE THREE-DIMENSIONAL HINDLIMB KINEMATICS
MS, University of Cincinnati, 2003, Arts and Sciences : Biological Sciences
Arboreal animals, especially lizards, often traverse three-dimensional networks of narrow perches with variable inclines, but the effects of both incline and narrow surfaces on the locomotor movement and function of limbs are poorly understood. Thus, I first quantified the three-dimensional hindlimb kinematics of a specialized arboreal lizard, Chamaeleo calyptratus, moving horizontally, and up and down a 30° incline on a narrow (2.4cm) perch and a flat surface. I compared the flat-surface data of C. calyptratus with those of an anatomically generalized terrestrial lizard, Dipsosaurus dorsalis. Second, I studied the hindlimb muscle activity of C. calyptratus on inclines of -45°, 0°, and 45°. I quantified electromyograms (EMGs) from nine hindlimb muscles, and correlated EMGs with three-dimensional hindlimb kinematics. Inclines had significant main effects for relatively few kinematic variables of C. calyptratus (11%) compared to D. dorsalis (73%). For kinematics of C. calyptratus, the main effects of the flat surface versus round perch were nearly three times more widespread than those of incline. The foot of C. calyptratus was markedly anterior to the hip at footfall, primarily as a result of an unusually extended knee for a lizard. A large amount of knee flexion during early stance may be used by C. calyptratus to actively pull the body forward in a manner not found in most other lizards and vertebrates. Despite the kinematics changing little with incline, the EMGs changed substantially. Most of the changes in EMGs were for amplitude rather than timing, and the hip and thigh muscle EMGs had more conspicuous changes with incline than those of the lower limb muscles. The knee flexion of C. calyptratus during the first half of stance was correlated with two large knee flexors which both increased in amplitude when moving uphill compared to level and downhill. Thus, early stance probably contributes significantly to propulsion in C. calyptratus. During stance, the EMGs of the caudofemoralis muscle in C. calyptratus correlated well with femur retraction, knee flexion, and posterior femur rotation, which provide propulsive forces. Many of the muscles in the hindlimb of C. calyptratus changed activity with incline in a manner similar to the propulsive limb muscles in mammals.

Committee:

Dr. Bruce C. Jayne (Advisor)

Subjects:

Biology, General

Keywords:

locomotion; muscle; lizard; kinematics; electromyography

Chen, YiRe-educating the injured spinal cord by operant conditioning of a reflex pathway
Doctor of Philosophy, The Ohio State University, 2006, Physiology
The activity-dependent plasticity is the foundation for normal spinal function. When spinal cord injury (SCI) interrupts the pathways of the spinal circuitry, normal input is altered, and pathological plasticity and abnormal reflexes develop. Thus, it becomes necessary to re-connect the interrupted spinal cord reflex pathways, and also to reshape or re-educate these pathways, to restore even partial function. Operant conditioning of the spinal stretch reflex (SSR) or its electrical analog, the H-reflex, provides a new method to induce long-term plasticity within the spinal cord. In response to an operant conditioning protocol, primates and rodents can gradually increase or decrease the reflex. The conditioning changes the spinal cord and appears to be dependent only on the corticospinal tract. The goal of this study was to determine whether H-reflex conditioning could help to modulate and guide normal functional recovery after SCI. The hypotheses were: (1) that up-conditioning of H-reflex will increase and down-conditioning will decrease the reflex during locomotion; (2) that H-reflex conditioning can reduce asymmetry in locomotion after SCI and that appropriate reflex conditioning can improve locomotion and restore function. These hypotheses were tested by studying soleus muscle activity during locomotion in normal rats and in rats with a lateral column (LC) transection before and after H-reflex conditioning. Results indicate that: 1) in normal rats in which the soleus H-reflex had been decreased by down-conditioning, the H-reflexes elicited during locomotion were also smaller. Similarly, the locomotor H-reflexes were larger in up-conditioned rats. However, the conditioning-induced changes did not affect the duration, length, or right/left symmetry of the step cycle. 2) in rats with LC transection in which a persistent asymmetry in treadmill locomotion was evident, up-conditioning increased the H-reflex and ameliorated the locomotor asymmetry. This improvement was accompanied by a significant increase in right soleus burst amplitude. In contrast, in LC rats without up-conditioning exposure, the locomotor asymmetry persisted and no other significant changes occurred. These results suggest that H-reflex conditioning may be able to reduce the functional deficits associated with SCI. In combination with other therapeutic methods, appropriate reflex conditioning may be able to maximize restoration of function after SCI.

Committee:

Lyn Jakeman (Advisor)

Subjects:

Biology, Neuroscience

Keywords:

Spinal cord injury; H-reflex conditioning; Locomotion

Simons, Verne F. H.Morphological Correlates of Locomotion in Anurans: Limb Length, Pelvic Anatomy and Contact Structures
Master of Science (MS), Ohio University, 2008, Biological Sciences (Arts and Sciences)

This study examines morphological features of the postcranial skeleton in a sample of modern anurans of known locomotor style within the context of a recent phylogenetic hypothesis. Non-destructive methods for collecting skeletal morphometric data from alcohol preserved anuran specimens are herein proposed and tested. Analysis of covariance (ANCOVA) is used to compare morphological structures taking into account differences in body size (SVL) among taxa.

Results of this study differ from previous studies in that the patterns of morphological correlates in anurans may not span the entire anuran clade, but are identifiable within phylogenetically focused comparisons. Manus size was predicted to be larger in arboreal than non arboreal anurans, a pattern supported by comparisons within the family Hylidae, and in the derived group Natatanura. Arboreal bufonid species exhibit wider sacra and longer fore- and hind limbs relative to SVL than do terrestrial species. natatanurans capable of long distance jumping exhibit a larger pes (wider and longer) relative to SVL than do arboreal species. Sacral diapophyseal angle (SDA) provides a method of separating walking/running species from all other locomotor groups examined with the exception of members of the strictly aquatic family Pipidae.

Fossil anuran specimens recently discovered in Oligocene deposits in the Rukwa Rift Basin of Tanzania preserve pelvic anatomy associated with forceful jumping in modern forms. An estimated sacral diapophyseal angle (SDA) for RRBP 04101 of 21.409° is consistent with this locomotor assessment.

Committee:

Nancy J. Stevens, PhD (Advisor); Scott Moody, PhD (Committee Member); Patrick O'Connor, PhD (Committee Member); Susan Williams, PhD (Committee Member)

Subjects:

Biology; Zoology

Keywords:

Anurans; Frogs; Morphometrics; Locomotion

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