//EXOFLEX
An Exoskeleton Glove for The Management of Hypermobile Type Ehlers Danlos Syndrome
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What is Hypermobile Ehlers Danlos Syndrome?
What is Hypermobile Ehlers Danlos Syndrome?
Hypermobile type Ehlers Danlos Syndrome (hEDS) is a genetic disorder that results in the hyperextension of joints. This can lead to many symptoms, some of the most under addressed are:
Muscle Weakness
Chronic Pain
Fatigue
A Proposed Solution
A Proposed Solution
Focusing on the under addressed symptoms of hEDS, a soft exoskeleton glove was proposed. The main 4 area of design were:
Mechanical Design
Electrical System
Software Design
Orthotic Ring Design
Mechanical System
Mechanical System
The mechanical system of the exoskeleton comprised of a DC motor, threaded spool, an idler bearing, tubing system, and orthotic rings.
Motor & Spool
Motor & Spool
The DC motor had a threaded spool on the shaft to assist with even unspool and respooling.
Idler Bearing
Idler Bearing
Used to keep tension in the system while the motor unspools and respools the cabling.
Braided Tension Line & Channel System
Braided Tension Line & Channel System
A tension line was created by using tackle line rated at 10lbs. A total of 10 strands were used to provide each finger with 2 subsections of the line. The line was fed through channel system on the hand to keep the system closed. This brought them to the orthotic ring's attachment posts.
Orthotic Ring Design
Orthotic Ring Design
Orthotic rings are a bracing treatment that prevents the hyperextension & subluxation of the finger joints. The design of them for the exoskeleton adds posts to the backs of the rings. These attachment posts provided anchoring points to the tension wires from the mechanical system.
Electrical Design
Electrical Design
The design of the electrical system resulted in two main focuses: the input system and the electromechanical output system. The input system used a flex sensor. The output system comprised of a DC motor and a motor driver board.
Flex Sensor
Flex Sensor
When a flex sensor is bent, the total resistance changes. The amount of bending is corresponded to by a value of 0 -1023. From expriamental testing, a threshold of 500 was set. If the value dropped below the threshold, the hand would close.
Arduino
Arduino
The Arduino Uno was the microcontroller chosen for the electrical system. It provided the digital and analog out channels needed for the electrical system.
DC Motor & Driver
DC Motor & Driver
A 12V DC motor was chosen for this application, as it produced a favorable output torque for its size and price. When the flex sensor bends, the DC motor turns clockwise.
Software Design
Software Design
The software developed for the system was developed in Arduino Uno's IDE. The software has 3 possible outcomes based on the flex sensor's values.
The hand has not moved, the motor does not turn
The hand closes, the motor turns clockwise
The hand opens, the motor turns counter clockwise
The code also checks for how long its been in a certain state and attempts to keep track of where the hand is.
The code's decision tree diagram can be seen to the left.
Different Iterations of the Exoskeleton Design
Different Iterations of the Exoskeleton Design
In order to settle on the best design to solve the design objectives, many different designs were fabricated and tested.
The first 2 designs were built at a scale model. The third lattice design and fabricated to scale; however, the durability was severely lacking.
The final orthotic rings in the design went through over 10 design iterations to get them to a satisfactory point. A few of these designs can be seen in the last image.
Featured in the Wentworth President's Report:
Featured in the Wentworth President's Report:
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For more In Depth Information:
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