Brett F. BuSha

An orthotic hand-assistive exoskeleton for actuated pinch and grasp

Over 450,000 Americans suffer from debilitative disorders resulting in the loss of proper hand function. A lightweight, non-cumbrous, orthotic hand exoskeleton was designed to restore normal pinching and grasping finger motions. Three functional digit mechanisms were designed: a thumb, index, and grouped third digit, comprised of the middle, ring, and small fingers. Each phalange was enclosed by a series of cylindrical aluminum bands connected at the centers of rotation of each joint. Bowden cables were mounted beneath each digit to provide active flexion, mimicking the tendons in the hand. A spring extension mechanism maintained constant tension in the Bowden cables, and during relaxation, returned the actuated digits to a fully extended resting position. Individually controlled actuators mounted on a forearm assembly produced 15 N of tensile force in each cable. The orthotic hand exoskeleton will be integrated with a digital control system currently under development in this laboratory. The complete system was designed to restore hand functionality through the amplification of precision pinch and/or power grasp.

Head motion controlled power wheelchair

Quadriplegics rely on power wheelchairs for mobility, but the hands-free controller systems currently available are obtrusive and expensive. The objective of this project was to design a power wheelchair with a novel control system for quadriplegics with head and neck mobility. The control system translates the position of the users head into speed and directional control of the wheelchair. Head movement was measured using camera-based motion-tracking of an infrared LED array on the back of the users head. The control system included a standby mode that was activated by pressing the head back against the headrest, which activated the braking system while deactivating the drive train, allowing for manual control of the wheelchair via a rear support system.

A power-assisted exoskeleton optimized for pinching and grasping motions

Over 450,000 Americans suffer from degenerative muscle diseases characterized by loss of strength and dexterity in the human hand. An assistive hand exoskeleton was designed to amplify residual muscle strength and restore functionality by assisting pinching and grasping motions. The device featured three movable digits: thumb, index, and middle-ring-small (MRS) digit. Adjustable straps wrapped around the exterior of the finger links and secured the users fingers inside the device. A microcontroller processed force sensing resistor (FSR) data and commanded articulating motors. The exoskeleton was lightweight, flexible, portable and accessible to a wide range of user finger diameters.

Orthotic Hand-Assistive Exoskeleton

Many people suffer from diseases that impair muscle function, resulting in decreased hand strength and a significant reduction in hand function. The objective of this project is to design and fabricate a powered exoskeleton that assists hand function and reduces the amount of muscular force needed to pinch and grasp. This device will be portable and easily manufactured, consisting of four major sub-systems: a mechanical exoskeleton, forearm support structure, biofeedback sensor array, and motor control system. The exoskeleton will be comprised of aluminum bands incorporated into a tight fitting glove. The mechanical exoskeleton will be actuated using braided polymer cables attached to three linear actuators via a simple pulley system that connects the most distal finger bands to the motors. The control system of the hand will incorporate a microcontroller that is coded to integrate data from the finger tip sensors to actuate the motors. A light weight, portable battery will be utilized as the power supply.

Gender and breathing route modulate cardio-respiratory variability in humans.

During spontaneous breathing, there is an intrinsic scaling of respiratory variability and a correlation between respiratory and heart rate variabilities. To identify the effect of breathing route on respiratory and heart rate variabilities, breath-to-breath interval (BBI) and heartbeat-to-heartbeat interval (RRI) were recorded from 12 female and 12 male adult subjects breathing through the nose or mouth. Temporal scaling within the BBI and RRI was quantified with detrended fluctuation analysis (DFA). We identified a significant gender-based breathing route interaction in the short-term scaling of BBI (p=0.007), a decrease in the short-term scaling of RRI during nose breathing (p=0.026), and a significant interdependence of short-term scaling of BBI and RRI in female subjects. We conclude that there is a gender-based differential effect of breathing route on the control of respiration and an increase in the random behavior of RRI associated with nasal breathing. These data also suggest the presence cardio-respiratory coupling of scaling behavior in female subjects.

Exercise modulation of cardiorespiratory variability in humans

Cardiorespiratory variability is the product of the integration of centrally generated rhythms with feedback from central and peripheral sensors. To quantify the effect of increased central drive on scaling patterns of cardiorespiratory activity, breath-to-breath interval (BBI) and heartbeat-to-heartbeat interval (RRI) were recorded from 17 female and 17 male adult subjects at rest and at two levels of mild exercise. Temporal scaling of BBI and RRI was quantified with detrended fluctuation analysis. Relative to a resting state, exercise induced a decrease in the short-term scaling of BBI (p=0.022), an increase in the long-term scaling of RRI (p=0.006), and abolished a significant positive linear relationship in females subjects (p=0.024) and a significant negative relationship in male subjects (p=0.025) in the short-term scaling of BBI and RRI. In conclusion, exercise has opposing effects on the control of breathing and heart rate, and modulates a divergent gender-based coupling of the temporal scaling of cardiorespiratory function.

Strength amplifying hand exoskeleton

Degenerative muscle diseases characterized by loss of strength and dexterity in the human hand significantly affect the physical, emotional, and social well-being of affected individuals. An assistive hand exoskeleton was designed to amplify residual muscle strength and improve functionality by assisting pinching and grasping motions. The device featured three movable finger components: thumb, index, and middle-ring-small (MRS). The exoskeleton and support structures were 3D printed using ABS thermoplastic. Feedback from embedded flex sensors and a force-sensing resistor were analyzed by a microcontroller, which individually commanded three linear electrical actuators. Actuators produced flexion through a cable-driven system, where monofilament polymer cables on the palmar side of the fingers, simulating the tendons of the human hand. The exoskeleton was lightweight, portable, and customizable.

A two-bit binary control system for an orthotic, hand-assistive exoskeleton

A combined 450,000 Americans suffer from multiple sclerosis, chronic carpal tunnel syndrome, and muscular dystrophy; debilitative disorders that result in a loss of muscle strength and dexterity within the afflicted individual. A controlled orthotic exoskeleton presents a solution by amplifying a users residual strength to restore precision pinch and/or power grasp motions. In order to optimize system response time and control accuracy, a two-bit binary state control algorithm was designed using LabVIEW v8.5. The states of the control system were refined using positional and object-sensing information supplied via negative feedback from Hall effect angular sensors and force sensing resistors. Forearm EMG was recorded and used to characterize hand strength with and without the mechanical assistance generated from the hand-assistive exoskeleton. The control system was tested using simulated sensor feedback data and has proven to be a robust design. The controller will be integrated with a glove-like, hand-based exoskeleton. The complete system was designed to restore hand functionality through the amplification of precision pinch and/or power grasp.

3-D printed hand assisstive exoskeleton for actuated pinch and grasp

In the United States over 1 million Americans suffer from muscular disorders such as Multiple Sclerosis, Carpal Tunnel Syndrome and Parkinsons disease. Muscular disorders can affect the skeletal muscles that control hand movements by reducing strength and dexterity resulting in a loss of the hands ability to perform everyday functional movements such as pinching and grasping. A power assistive exoskeleton was designed to amplify a users residual strength and restore functional movements. This device incorporates a multi-digit mechanism comprising of a thumb, index, and grouped third MRS (middle, ring, small) digit. Each digit will provide flexion/extension through the coupling of a solenoid pneumatic actuator and a double action pneumatic cylinder working in compression. The double action pneumatic cylinders are connected to a polymer-braided cable that can produce a force on each digit allowing it to actuate. The solenoid pneumatic actuator is powered through a control system that receives sensor feedback from force sensing resistors placed on each digit, and converts it to an electrical signal. Preliminary testing will include the utilization of forearm EMG data obtained when the user performs daily tasks such as picking up a pencil, a 5 lb bag, and a water bottle with the exoskeleton. These results should present a reduction in pinching and grasping effort with respect to normal force production in each subject tested, and thereby successfully amplifying these movements and restoring hand functionality.

A stochastic and integrative model of breathing

Human breathing patterns contain both temporal scaling characteristics, and an innately random component. A stochastic and mathematically integrative model of breathing (SIMB) that simulated the natural random and fractal-like pattern of human breathing was designed using breath-to-breath interval (BBI) data recorded from 14 healthy subjects. Respiratory system memory was estimated with autocorrelation, and a probability density function (PDF) was created by fitting a polynomial curve to each normalized BBI sequence histogram. SIMB sequences were produced by randomly selecting BBI values using a PDF and imparting memory with an autocorrelation-based function. Temporal scaling was quantified with detrended fluctuation analysis. The SIMB BBI sequences were embedded with significant fractal scaling (p<0.001) that was similar to the human data (p>0.05), and increasing SIMB output length did not alter the temporal scaling (p>0.05). This study demonstrated a new computational model that can reproduce the inherent stochastic and time scaling characteristics of human breathing.