Publications by authors named "Ryan Farris"

This paper describes the development and evaluation of a novel, threshold-based gait event detection algorithm utilizing only one thigh inertial measurement unit (IMU) and unilateral, sagittal plane hip and knee joint angles. The algorithm was designed to detect heel strike (HS) and toe off (TO) gait events, with the eventual goal of detection in a real-time exoskeletal control system. The data used in the development and evaluation of the algorithm were obtained from two gait databases, each containing synchronized IMU and ground reaction force (GRF) data.

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Exoskeleton technology has undergone significant developments for the adult population but is still lacking for the pediatric population. This paper presents the design of a hip-knee exoskeleton for children 6 to 11 years old with gait abnormalities. The actuators are housed in an adjustable exoskeleton frame where the thigh part can adjust in length and the hip cradle can adjust in the medial-lateral and posterior-anterior directions concurrently.

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This paper presents an innovative design methodology for development of lower limb exoskeletons with the fabrication and experimental evaluation of prototype hardware. The proposed design approach is specifically conceived to be suitable for the pediatric population and uses additive manufacturing and a model parameterized in terms of subject anthropometrics to give a person-specific custom fit. The methodology is applied to create computer-aided design models using average anthropometrics of children 6-11 years old and using anthropometrics of an individual measured by the researchers.

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This paper describes the effects of a novel functional electrical stimulation (FES) system which has been integrated in a powered exoskeleton to provide up to 10 channels of stimulation to users with paraplegia via surface electrodes. Experimental data collected from three users with spinal cord injury (SCI) indicate the system reduced the exoskeleton motor torques necessary to perform sit-to-stand transitions in the exoskeleton. All subjects exhibited reduced muscle spasticity immediately after walking in the exoskeleton with FES.

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5-Fluorouracil (5-Fu) is commonly used chemotherapy drug, but it can lead to the impairment of cognitive function. The pathogenesis of this injury is unknown but may involve modifications to dendritic structure and/or alterations in dendritic spine density and morphology. Dendritic spines are sites of excitatory synaptic transmission and changes in spine structure and dendrite morphology are thought to represent a morphological correlate of altered brain functions associated with hippocampal dependent learning and memory.

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Background: Loss of legged mobility due to spinal cord injury (SCI) is associated with multiple physiological and psychological impacts. Powered exoskeletons offer the possibility of regained mobility and reversal or prevention of the secondary effects associated with immobility.

Objective: This study was conducted to evaluate mobility outcomes for individuals with SCI after 5 gait-training sessions with a powered exoskeleton, with a primary goal of characterizing the ease of learning and usability of the system.

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A hallmark of cystic fibrosis (CF) lung disease is neutrophilic airway inflammation. Elevated neutrophil counts have been associated with decreased forced expiratory volume in 1 second and poor clinical measures in patients with CF. Interleukin 8 (IL-8), epithelial neutrophil activating protein 78 (ENA-78), tumor necrosis factor alpha (TNF-α), granulocyte macrophage colony-stimulating factor (GM-CSF), and granulocyte colony-stimulating factor (G-CSF) contribute to neutrophil activation and disease pathogenesis in the airways of patients with CF.

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This paper presents an assessment of a lower limb exoskeleton for providing legged mobility to people with paraplegia. In particular, the paper presents a single-subject case study comparing legged locomotion using the exoskeleton to locomotion using knee-ankle-foot orthoses (KAFOs) on a subject with a T10 motor and sensory complete injury. The assessment utilizes three assessment instruments to characterize legged mobility, which are the timed up-and-go test, the Ten-Meter Walk Test (10 MWT), and the Six-Minute Walk Test (6 MWT), which collectively assess the subject's ability to stand, walk, turn, and sit.

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Efforts have recently been reported by several research groups on the development of computer-controlled lower limb orthoses to enable legged locomotion in persons with paraplegia. Such systems must employ a control framework that provides essential movements to the paraplegic user (i.e.

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The authors describe a cooperative controller that combines the knee joint actuation of an externally powered lower limb exoskeleton with the torque and power contribution from the electrically stimulated quadriceps muscle group. The efficacy of combining these efforts is experimentally validated with a series of weighted leg lift maneuvers. Measurements from these experiments indicate that the control approach effectively combines the respective efforts of the motor and muscle, such that good control performance is achieved, with substantial torque and energy contributions from both the biological and non-biological actuators.

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This paper describes the application of a powered lower limb exoskeleton to aid paraplegic individuals in stair ascent and descent. A brief description of the exoskeleton hardware is provided along with an explanation of the control methodology implemented to allow stair ascent and descent. Tests were performed with a paraplegic individual (T10 complete injury level) and data is presented from multiple trials, including the hip and knee joint torque and power required to perform this functionality.

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This paper describes the design and implementation of a cooperative controller that combines functional electrical stimulation (FES) with a powered lower limb exoskeleton to provide enhanced hip extension during the stance phase of walking in persons with paraplegia. The controller utilizes two sources of actuation: the electric motors of the powered exoskeleton and the user's machine (FSM), a set of FES. It consists of a finite-state machine (FSM), a set of proportional-derivative (PD) controllers for the exoskeleton and a cycle-to-cycle adaptive controller for muscle stimulation.

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This paper describes a powered lower-limb orthosis that is intended to provide gait assistance to spinal cord injured (SCI) individuals by providing assistive torques at both hip and knee joints, along with a user interface and control structure that enables control of the powered orthosis via upper-body influence. The orthosis and control structure was experimentally implemented on a paraplegic subject (T10 complete) in order to provide a preliminary characterization of its capability to provide basic walking. Data and video is presented from these initial trials, which indicates that the orthosis and controller are able to effectively provide walking within parallel bars at an average speed of 0.

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This paper describes a powered lower-limb orthosis that is intended to provide gait assistance to spinal cord injured (SCI) individuals by providing assistive torques at both hip and knee joints. The orthosis has a mass of 12 kg and is capable of providing maximum joint torques of 40 Nm with hip and knee joint ranges of motion from 105° flexion to 30° extension and 105° flexion to 10° hyperextension, respectively. A custom distributed embedded system controls the orthosis with power being provided by a lithium polymer battery which provides power for one hour of continuous walking.

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High-throughput sequencing of 16S rRNA genes has increased our understanding of microbial community structure, but now even higher-throughput methods to the Illumina scale allow the creation of much larger datasets with more samples and orders-of-magnitude more sequences that swamp current analytic methods. We developed a method capable of handling these larger datasets on the basis of assignment of sequences into an existing taxonomy using a supervised learning approach (taxonomy-supervised analysis). We compared this method with a commonly used clustering approach based on sequence similarity (taxonomy-unsupervised analysis).

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This paper presents preliminary results on the development of a powered lower limb orthosis intended to provide legged mobility (with the use of a stability aid, such as forearm crutches) to paraplegic individuals. The orthosis contains electric motors at both hip and both knee joints, which in conjunction with ankle-foot orthoses, provides appropriate joint kinematics for legged locomotion. The paper describes the orthosis and the nature of the controller that enables the SCI patient to command the device, and presents data from preliminary trials that indicate the efficacy of the orthosis and controller in providing legged mobility.

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This paper proposes a new configuration for a hybrid-FES gait restoration system, and presents a combination of simulation and experiment that support the feasibility of the proposed approach. Gait simulation results are presented that indicate the majority of load bearing and the majority of power for gait is provided by the legs (i.e.

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Given the growing wealth of downstream information, the integration of molecular and non-molecular data on a given organism has become a major challenge. For micro-organisms, this information now includes a growing collection of sequenced genes and complete genomes, and for communities of organisms it includes metagenomes. Integration of the data is facilitated by the existence of authoritative, community-recognized, consensus identifiers that may form the heart of so-called information knuckles.

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