USB Interface Technology for Individuals with Limited Upper Limb Mobility

This image shows the casing for the device

Heather Anderson, Isidro Magaña, Ashley Thibodeaux, Zachary Wells (Louisiana Tech University)

ABSTRACT

Individuals with spinal cord injuries have limited motor function and thus have difficulties plugging USB devices into computers. We propose to replace the physical element of USB connections with magnetic force over copper leads housed in an ABS casing. This will allow for consumers to easily connect and disconnect USB devices without fine motor skills. The device has been tested for data transfer speeds to ensure it meets USB 2.0 specifications. The device has also been tested with consumers of varying mobility levels to determine overall satisfaction with the proposed solution.

BACKGROUND

The rapid growth in computer use due to the recent technological surge has made it important that one can interface with computers and technological devices. Computers are used by 75% of adult women and 73% of adult men in the United States (1). Computer use has opened doors for people with disabilities to communicate and further integrate in society.

Although technology has helped the disabled, it has also created barriers, particularly for those with motor impairments using USB devices. The number of products with USB interface is growing at a rapid pace, and there are currently over 6 billion of these products in the market today (2). Many assistive technologies created specifically for helping people with motor impairments in their upper limbs and hands, such as special keyboards, wireless mice, and adaptive buttons/switches, commonly require USB interfaces for use. The act of plugging in the USB flash drive or cable to operate these devices hinders a person with upper limb and hand mobility impairment. This problem has yet to be solved and continues to be an issue among those with upper limb or hand impairments considering 36% and 29% are the “percentages of people ages 15 to 64 with a severe disability who use a computer and the internet at home” (3). In 2004, the estimated total of people with some level of disability was around 58.7 million (4). Of these, 2 million adults with arthritis reported having problems with grasping objects (5), along with many other functional limitations that hinder them in daily activities and in the workforce.

People with motor impairments have found it difficult to find and maintain a job. In the same May 2007 report, 56% of people ranging from 21-64 years old were reported as having some level of disability while also being employed (3). Furthermore, 11.8 million people from 16-64 years old reported having difficulties finding and maintaining a job due to a disability (3). Therefore it is essential to find a way to allow these individuals with motor impairments to participate in this technologically driven world, so that they can be highly independent in all areas of life.

Currently there is no solution for the problem of plugging and unplugging USB operated devices. Therefore, an assistive device is needed to close the gap between USB use and disability constraints.

STATEMENT OF PROBLEM

We propose a device that would allow people with little to no use of their hands to connect and disconnect USB devices. This device would give people with disabilities greater independence and enhanced safety by removing the need to use the mouth or for a caretaker’s assistance to insert or remove USB devices. The gained independence allowed to these people by our proposed device could ease their difficulty in maintaining a job without the need for assistance. Through this device, we can help people interact with a prominent technology in an easy and cost-effective way.

METHODS

Alternative Solutions Considered

Assistive technological devices that have been considered include motorized hand technology, wireless data transfer for USB flash drive, auto-loading lock (similar to optical drive loading) for USB device, and the USB interface technological device. The approach that applies to the general need for plugging and unplugging a various range of USB devices and is the most feasible considering the time and money constraints is the USB interface technological device.

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figure 1: This image shows the casing for the device

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The USB interface technological device shown in figure 1 employs the use of magnets to hold the male and female sections of the prototype together to ensure a solid connection between the exposed copper leads on both sections. Both pieces are designed using CAD software and are machined out of ABS. The female piece is designed to hold a USB device such as a flash drive securely and be handled and transported by the consumer using a rubber loop connected to the top of the device. Because of the magnets and open lead faces of both sections of the device, the consumer must simply position the device near the male end connected to a computer to allow for magnetic force to pull the sections together and create a connection.

Specific Aims

Several specific aims were developed to guide the course of this design process. Specific aim 1 was to determine the scope of the problem. This specific aim was split into 1.1 – meet with the consumer to determine the level of need, 1.2 – produce design specifications based on consumer feedback, and 1.3 – perform feasibility testing. Specific aim 2 was to design the device. This specific aim was split into 2.1 – design device to fit product specifications, 2.2 – build device components, and 2.3 – assemble the device. Specific aim 3 was to test the device. This specific aim was split into 3.1 – verification testing against product specs, 3.2 – safety testing, 3.3 – test on different levels of mobility, and 3.4 – validation testing with the consumer to evaluate satisfaction.

RESULTS

The device was built according to our product specifications. Measurements such as the dimensions and weight were recorded for comparison with the product specifications. The power was measured across the two supply leads and was determined to match USB 2.0 standards of +/- 5 volts. The temperature of the device was monitored during extended operation and it was determined to not pose a fire hazard. The current across each lead was measured and determined to be negligible and therefore the device carries no hazard of electrical shock. Table 1 below reports the values of the various findings.

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Table 1: This table contains the measured parameters for the device

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The device was tested numerous times by the team members to ensure its continued functionality and was also tested with two consumers. The consumer evaluated the device based on a performance chart which allowed them to rate on a scale of 1 to 5 the various components: overall ease of use, size of USB adapter, ease of use of handle, weight of device, ability to connect adapter, ability to disconnect the device, overall functionality, overall appearance, possibility of purchasing this device if on market. The consumer was also able to verbally describe any suggestions they might have regarding the device and its operation.

DISCUSSION

The USB interface device described in this report would be beneficial to persons with limited upper limb mobility because it would allow them to connect and disconnect USB devices using only gross muscle control. This device performed well with consumers suffering from spinal cord injury, however the consumer with severe cerebral palsy had more difficulty using the smaller loop-shaped handle we provided. The handle on this design could be customized on a per-consumer basis to maximize user satisfaction. This device also has the potential for a hub addition that would allow a few devices to be used in series.

IMPLICATIONS

The total cost for one male and female adapter is $40.05. A typical consumer setup might include 4 male adapters at home and work for a total of 8, as well as 4 female adapters which puts the total cost at $240.31. Relative to available assistive technology this device is reasonably price. Mass-production techniques would significantly decrease the total cost of USB interface device.

REFERENCES

1. Computer usage in the U.S. (2008, December). October 27, 2009, Infoplease: Pew internet & American life project tracking survey.

2. Reviews and news on tech products, software and downloads: SuperSpeed USB 3.0. October 30, 2009, PC World.

3. US census press releases- Americans with disabilities act: July 26. (2007, May 29). October 24, 2009, Census bureau home page.

4. People with disabilities in the United States. (2001, March 16). October 30, 2009, U.S. census bureau.

5. Arthritis: data and statistics. (2009, October 28). October 30, 2009, CDC: Centers for disease control and prevention: cdc.gov.

ACKOWLEDGEMENTS

We would like to acknowledge the funding of this project through the Center for Rehabilitation Engineering Science and Technology at Louisiana Tech University.