Soft-bodied marine invertebrates comprise a keystone component of ocean ecosystems; however, we k... more Soft-bodied marine invertebrates comprise a keystone component of ocean ecosystems; however, we know little of their behaviors and physiological responses within their natural habitat. Quantifying ocean conditions and measuring organismal responses to the physical environment is vital to understanding the species or ecosystemlevel influences of a changing ocean.
Soft-bodied marine invertebrates comprise a keystone component of ocean ecosystems; however, we
k... more Soft-bodied marine invertebrates comprise a keystone component of ocean ecosystems; however, we know little of their behaviors and physiological responses within their natural habitat. Quantifying ocean conditions and measuring organismal responses to the physical environment is vital to understanding the species or ecosystemlevel influences of a changing ocean.
ASME 2009 Summer Bioengineering Conference, Parts A and B, 2009
ABSTRACT Posturographic data collected during quiet stance using force plates is widely used to a... more ABSTRACT Posturographic data collected during quiet stance using force plates is widely used to assess postural stability [1]. Center of pressure (COP) is a commonly used experimental variable for several types of analyses. Traditionally, COP data have been analyzed using measures that describe the shape or speed of the trajectory [1]. Unfortunately, these parameters do not provide insight into the physiological system as a whole and have been shown to have questionable reliability [2].
ASME 2011 Dynamic Systems and Control Conference and Bath/ASME Symposium on Fluid Power and Motion Control, Volume 2, 2011
ABSTRACT Ankle-foot orthoses (AFOs) are used to assist persons with lower-limb neuromuscular impa... more ABSTRACT Ankle-foot orthoses (AFOs) are used to assist persons with lower-limb neuromuscular impairments. We have developed the portable powered AFO (PPAFO). This device uses a bidirectional pneumatic actuator powered by a CO2 bottle to provide dorsiflexor and plantarflexor torque assistance. The PPAFO operates tether-free, allowing for use outside of the laboratory. This system has been tested on one impaired and multiple healthy subjects. Timing of the assistance provided by the PPAFO has been determined by: 1) direct event detection using sensor feedback with threshold triggers, and 2) state estimation in which gait events are estimated using a cross-correlation based algorithm. Direct event detection, while simple to implement, can be unreliable for subjects with certain gait impairments. State estimation, while more complicated to implement, provides access to state information that cannot be directly measured by the AFO, which allows for greater flexibility in assistance timing. Current hardware limitations and future work are also discussed.
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2011
Ankle-foot orthoses (AFOs) ameliorate the impact of impairments to the lower limb neuromuscular m... more Ankle-foot orthoses (AFOs) ameliorate the impact of impairments to the lower limb neuromuscular motor system that affect gait. Emerging technologies provide a vision for fully powered, untethered AFOs. The portable powered AFO (PPAFO) provides both plantarflexor and dorsiflexor torque assistance via a bi-directional pneumatic rotary actuator. The system uses a portable pneumatic power source (bottle of compressed CO(2)) and embedded electronics to control foot motion during level walking. Experimental data were collected to demonstrate functionality from two subjects with bilateral impairments to the lower legs. These data demonstrated the PPAFO's ability to provide functional assistance during gait. The stringent design requirements of light weight, small size, high efficiency and low noise make the creation of daily wear assist devices challenging; but once such devices appear, they will present new opportunities for clinical treatment of gait abnormalities.
ASME 2008 Summer Bioengineering Conference, Parts A and B, 2008
ABSTRACT In this paper, we present a novel ankle-foot-orthosis (AFO) design that controls ankle m... more ABSTRACT In this paper, we present a novel ankle-foot-orthosis (AFO) design that controls ankle motion by providing a plantarflexion stop with free dorsiflexion during gait. The biomechanical controls are accomplished with a unique application of a cam-follower design that uses pneumatic power harvested via an air bellow embedded into the insole of the AFO (Figure 1). This portable design is self-contained and does not require any external power source to provide for the plantarflexion stop locking mechanism. It is the first step in a series of untethered fluid-powered orthotic devices.
Attaching bio-telemetry or -logging devices ('tags') to marine animals for research and m... more Attaching bio-telemetry or -logging devices ('tags') to marine animals for research and monitoring adds drag to streamlined bodies, thus affecting posture, swimming gaits and energy balance. These costs have never been measured in free-swimming cetaceans. To examine the effect of drag from a tag on metabolic rate, cost of transport and swimming behavior, four captive male dolphins (Tursiops truncatus) were trained to swim a set course, either non-tagged (n=7) or fitted with a tag (DTAG2; n=12), and surface exclusively in a flow-through respirometer in which oxygen consumption VO₂ and carbon dioxide production (VO₂; ml kg(-1) min(-1)) rates were measured and respiratory exchange ratio (VO₂/resting VO₂) was calculated. Tags did not significantly affect individual mass-specific oxygen consumption, physical activity ratios (exercise /resting ), total or net cost of transport (COT; J m(-1) kg(-1)) or locomotor costs during swimming or two-minute recovery phases. However, individu...
The Journal of the Acoustical Society of America, 2013
ABSTRACT From Kooyman's 1963 wind-up kitchen timer TDR, multi-sensor tags have evolved si... more ABSTRACT From Kooyman's 1963 wind-up kitchen timer TDR, multi-sensor tags have evolved significantly over the last twenty years. These advancements, including high fidelity acoustics, have been driven by improved sensing and electronics technology, and resulted in highly integrated mechatronics systems for the study of free ranging animals. In the next decade, these tags will continue to improve, and promising work has begun in three key areas: (i) new sensors; (ii) expanding uses of existing sensors; and (iii) increasing attachment duration and reliability. The addition of rapid acquisition GPS and the inclusion of gyroscopes to separate the dynamic acceleration of the animal from gravitational acceleration, are underway but not widely available to the community. Existing sensors could be used for more and different applications, e.g., measuring ambient ocean noise. Tags attached to pinnipeds in the Southern Ocean, for example, could provide noise measurements from remote areas. Finally, attachment duration has been limiting for cetaceans because the suction cups typically used do not reliably stay attached for more than a day. We will present data on engineering efforts to improve attachments: (i) improved tag hydrodynamics; (ii) incorporating bio-compatible glues; and (iii) micro structuring tag components to utilize hydrostatic forces and enhance adhesion.
Soft-bodied marine invertebrates comprise a keystone component of ocean ecosystems; however, we k... more Soft-bodied marine invertebrates comprise a keystone component of ocean ecosystems; however, we know little of their behaviors and physiological responses within their natural habitat. Quantifying ocean conditions and measuring organismal responses to the physical environment is vital to understanding the species or ecosystemlevel influences of a changing ocean.
Soft-bodied marine invertebrates comprise a keystone component of ocean ecosystems; however, we
k... more Soft-bodied marine invertebrates comprise a keystone component of ocean ecosystems; however, we know little of their behaviors and physiological responses within their natural habitat. Quantifying ocean conditions and measuring organismal responses to the physical environment is vital to understanding the species or ecosystemlevel influences of a changing ocean.
ASME 2009 Summer Bioengineering Conference, Parts A and B, 2009
ABSTRACT Posturographic data collected during quiet stance using force plates is widely used to a... more ABSTRACT Posturographic data collected during quiet stance using force plates is widely used to assess postural stability [1]. Center of pressure (COP) is a commonly used experimental variable for several types of analyses. Traditionally, COP data have been analyzed using measures that describe the shape or speed of the trajectory [1]. Unfortunately, these parameters do not provide insight into the physiological system as a whole and have been shown to have questionable reliability [2].
ASME 2011 Dynamic Systems and Control Conference and Bath/ASME Symposium on Fluid Power and Motion Control, Volume 2, 2011
ABSTRACT Ankle-foot orthoses (AFOs) are used to assist persons with lower-limb neuromuscular impa... more ABSTRACT Ankle-foot orthoses (AFOs) are used to assist persons with lower-limb neuromuscular impairments. We have developed the portable powered AFO (PPAFO). This device uses a bidirectional pneumatic actuator powered by a CO2 bottle to provide dorsiflexor and plantarflexor torque assistance. The PPAFO operates tether-free, allowing for use outside of the laboratory. This system has been tested on one impaired and multiple healthy subjects. Timing of the assistance provided by the PPAFO has been determined by: 1) direct event detection using sensor feedback with threshold triggers, and 2) state estimation in which gait events are estimated using a cross-correlation based algorithm. Direct event detection, while simple to implement, can be unreliable for subjects with certain gait impairments. State estimation, while more complicated to implement, provides access to state information that cannot be directly measured by the AFO, which allows for greater flexibility in assistance timing. Current hardware limitations and future work are also discussed.
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2011
Ankle-foot orthoses (AFOs) ameliorate the impact of impairments to the lower limb neuromuscular m... more Ankle-foot orthoses (AFOs) ameliorate the impact of impairments to the lower limb neuromuscular motor system that affect gait. Emerging technologies provide a vision for fully powered, untethered AFOs. The portable powered AFO (PPAFO) provides both plantarflexor and dorsiflexor torque assistance via a bi-directional pneumatic rotary actuator. The system uses a portable pneumatic power source (bottle of compressed CO(2)) and embedded electronics to control foot motion during level walking. Experimental data were collected to demonstrate functionality from two subjects with bilateral impairments to the lower legs. These data demonstrated the PPAFO's ability to provide functional assistance during gait. The stringent design requirements of light weight, small size, high efficiency and low noise make the creation of daily wear assist devices challenging; but once such devices appear, they will present new opportunities for clinical treatment of gait abnormalities.
ASME 2008 Summer Bioengineering Conference, Parts A and B, 2008
ABSTRACT In this paper, we present a novel ankle-foot-orthosis (AFO) design that controls ankle m... more ABSTRACT In this paper, we present a novel ankle-foot-orthosis (AFO) design that controls ankle motion by providing a plantarflexion stop with free dorsiflexion during gait. The biomechanical controls are accomplished with a unique application of a cam-follower design that uses pneumatic power harvested via an air bellow embedded into the insole of the AFO (Figure 1). This portable design is self-contained and does not require any external power source to provide for the plantarflexion stop locking mechanism. It is the first step in a series of untethered fluid-powered orthotic devices.
Attaching bio-telemetry or -logging devices ('tags') to marine animals for research and m... more Attaching bio-telemetry or -logging devices ('tags') to marine animals for research and monitoring adds drag to streamlined bodies, thus affecting posture, swimming gaits and energy balance. These costs have never been measured in free-swimming cetaceans. To examine the effect of drag from a tag on metabolic rate, cost of transport and swimming behavior, four captive male dolphins (Tursiops truncatus) were trained to swim a set course, either non-tagged (n=7) or fitted with a tag (DTAG2; n=12), and surface exclusively in a flow-through respirometer in which oxygen consumption VO₂ and carbon dioxide production (VO₂; ml kg(-1) min(-1)) rates were measured and respiratory exchange ratio (VO₂/resting VO₂) was calculated. Tags did not significantly affect individual mass-specific oxygen consumption, physical activity ratios (exercise /resting ), total or net cost of transport (COT; J m(-1) kg(-1)) or locomotor costs during swimming or two-minute recovery phases. However, individu...
The Journal of the Acoustical Society of America, 2013
ABSTRACT From Kooyman's 1963 wind-up kitchen timer TDR, multi-sensor tags have evolved si... more ABSTRACT From Kooyman's 1963 wind-up kitchen timer TDR, multi-sensor tags have evolved significantly over the last twenty years. These advancements, including high fidelity acoustics, have been driven by improved sensing and electronics technology, and resulted in highly integrated mechatronics systems for the study of free ranging animals. In the next decade, these tags will continue to improve, and promising work has begun in three key areas: (i) new sensors; (ii) expanding uses of existing sensors; and (iii) increasing attachment duration and reliability. The addition of rapid acquisition GPS and the inclusion of gyroscopes to separate the dynamic acceleration of the animal from gravitational acceleration, are underway but not widely available to the community. Existing sensors could be used for more and different applications, e.g., measuring ambient ocean noise. Tags attached to pinnipeds in the Southern Ocean, for example, could provide noise measurements from remote areas. Finally, attachment duration has been limiting for cetaceans because the suction cups typically used do not reliably stay attached for more than a day. We will present data on engineering efforts to improve attachments: (i) improved tag hydrodynamics; (ii) incorporating bio-compatible glues; and (iii) micro structuring tag components to utilize hydrostatic forces and enhance adhesion.
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Papers by Alex Shorter
know little of their behaviors and physiological responses within their natural habitat. Quantifying ocean conditions
and measuring organismal responses to the physical environment is vital to understanding the species or ecosystemlevel influences of a changing ocean.
know little of their behaviors and physiological responses within their natural habitat. Quantifying ocean conditions
and measuring organismal responses to the physical environment is vital to understanding the species or ecosystemlevel influences of a changing ocean.