Developing an Open Source Sonar Navigation Device

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#### Vision Rehabilitation International

Guide Dogs NSW/ACT

Subject: Health Care Sciences & Services, Medicine, Rehabilitation

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VOLUME 4 , ISSUE 1 (April 2011) > List of articles

### Developing an Open Source Sonar Navigation Device

Citation Information : International Journal of Orientation & Mobility. Volume 4, Issue 1, Pages 92-98, DOI: https://doi.org/10.21307/ijom-2011-011

Published Online: 16-April-2018

### ARTICLE

#### ABSTRACT

Commercial assistive devices tend to be expensive and difficult for the user to customise to their specific needs. We have developed a hand mounted sonar navigation device designed specifically to be vastly more affordable, while being easy for individuals to both make and customise. This paper covers the process of developing the device, publishing complete details of the device, and the results of having interested individuals make their own version.

## Background

Comparatively few companies pursue assistive technology because the market is small and highly regulated. This makes the devices offered limited in function and expensive, as well as out of reach for many people who need them.

Recently the ability for individuals to create sophisticated custom electronic devices has expanded dramatically. In the last several years the cost of complex electronic components have dropped, become easier to use, and well documented making it possible for people with a hobbyist level of skill to build unique and useful projects. These factors combine to make it straightforward for people without special training to connect sensors, motors, and other electromechanical devices together with sophisticated logic and programming to create complex devices.

With the increasing availability of these technologies has risen the concept of Open Source Hardware, which makes the full design for a device available for anyone to make, improve and modify it to their own use (OSHW Committee, 2011).

The combination of these two concepts, allowing the average person to make advanced devices and the open sharing of complete device designs has positive implications for assistive technology. Starting from free instructions, a hobbyist would be able build a sophisticated assistive device that can be customised to serve an individual’s specific needs, while still costing less than more general commercial offerings.

This project explores the process first by developing a hand mounted sonar navigation device, then offering the complete plans and instructions to the community and finally observing the results of those who chose to build, modify, and use the device.

## Concept

Through working on a virtual navigation project for people with vision impairment we found that ultrasonic sensors provided excellent navigation cues. After investigating the current state of ultrasonic navigation aids we decided to create our own.

##### Figure 2.

The tacit haptic glove.

## Response

After completing the initial design we published on our web site full plans for the device including a demonstration video, development notes, full plans, schematics, illustration, parts list, programming code, and a pattern for the gauntlet. These were released under a license that allowed free copying, redistribution, modification, and also allowed individuals to make their own.

Response was strong and immediate. Within 24 hours more than 10,000 people had visited the page, and it received coverage by national and international media. We also received a large volume of email from people who were blind as well as sighted individuals who were interested in helping family, friends, and community members with vision impairment. The nature and volume of the feedback clearly showed the demand for affordable and accessible assistive technology.

Not all feedback was positive, however. The most common complaint was that the individual did not know someone who had the skills to construct the device. Another common complaint was that it was difficult or impossible for a person with vision impairment to make one for himself.

In the months following its release a number of people built Tacit devices based on our original plans. Several people freely contributed improvements in the design and function. Others have reported making custom versions for their individual needs, such as an illuminated pointer to help an assistant identify objects that they sense, and adding a switch for shorter range finding to help location objects on a table. Other builders simplified the design to have only a single sensor and servo, making the design more compact.

Because we are only publishing plans for the device, this project has not gone through governmental approval common for most assistive devices. This makes it incumbent on the developer and builder to make sure the device is safe and effective. We have done our best to design something that maximises safety and effectiveness, and we believe that even in the worst case the chance for personal danger is virtually nonexistent. However, with the Open Source Hardware model we have no control over those who build the device, or the changes they make in the design. A number of the custom versions made changes that disregarded our research. A common change was to simply attach the device to a glove rather than build a gauntlet. While not dangerous the change somewhat compromises the sense of touch on the worn hand. Another, common, but more serious change was to use vibration motors even though research showed the possibility of numbness and nerve damage from doing so.

From the perspective of the individual builders these changes made sense since they simplify the construction. However, we were surprised that makers would so easily disregard the research and benefits of the design.

While it is impossible to know exactly how many people have chosen to build or use the device we collected feedback from the 23 builders who contacted us to share their product.

• Total devices built: 23

• Devices changed from the design: 23 (100%)

• Device changes contraindicated by research: 6 (26%)

• Builders who shared improvements: 7 (30%)

• Users who found the device useful: 20 (87%)

## Results

In general we consider the project a success. We produced plans for a device that when properly built is a small fraction of the price of similar devices. In sharing the plans we found that many people were introduced to a new class of accessibility devices that they were unable to have before. Finally by incorporating improvements from the community a higher quality device was the result. Unique, custom devices were created to serve the needs of the individual.

The main drawback of the project is that the devices can be built in ways that might endanger the user. While we went to lengths to explain the safety of certain features there is no way to prevent someone from ignoring them when they build their own device.

We are now working on a second version of the project that will possibly be produced as a kit. The kit will be much easier to build, allowing the devices to get ‘on the hands of’ more people who need them, discouraging those who would take possibly troublesome short cuts, but allowing those who want to customise the design to do so.

While the results are not exclusively positive, we think Open Hardware assistive devices, if carefully designed, provide much more help than harm and we will continue to develop the concept further.

## References

1. Calder, D. J. (2009). Assistive technology interfaces for the blind. 2009 3rd IEEE International Conference on Digital Ecosystems and Technologies, 318-323. Ieee. Retrieved from http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=5276752
[CROSSREF] [URL]
2. Lundborg, G., Dahlin, L. B., Hansson, H. A., Kanje, M., & Necking, L. E. (1990). Vibration exposure and peripheral nerve fiber damage. The Journal of Hand Surgery, 15(2), 346-351.
[CROSSREF]
3. Moxon, R., Allison, A., & England, G. C. W. (2010). Effect of ultrasonic devices on the distraction behavior of guide dogs. International Journal of Orientation & Mobility, 3(1), 27-31.
[CROSSREF]
4. OSHW Definition Committee. (2011). Open Source Hardware (OSHW) Definition 1.0. Retrieved from http://freedomdefined.org/OSHW#Open_Source_Hardware_.28OSHW.29_Definition_1.0
[URL]

### FIGURES & TABLES

Figure 1.

The tacit haptic glove.

Figure 2.

The tacit haptic glove.

### REFERENCES

1. Calder, D. J. (2009). Assistive technology interfaces for the blind. 2009 3rd IEEE International Conference on Digital Ecosystems and Technologies, 318-323. Ieee. Retrieved from http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=5276752
[CROSSREF] [URL]
2. Lundborg, G., Dahlin, L. B., Hansson, H. A., Kanje, M., & Necking, L. E. (1990). Vibration exposure and peripheral nerve fiber damage. The Journal of Hand Surgery, 15(2), 346-351.
[CROSSREF]
3. Moxon, R., Allison, A., & England, G. C. W. (2010). Effect of ultrasonic devices on the distraction behavior of guide dogs. International Journal of Orientation & Mobility, 3(1), 27-31.
[CROSSREF]
4. OSHW Definition Committee. (2011). Open Source Hardware (OSHW) Definition 1.0. Retrieved from http://freedomdefined.org/OSHW#Open_Source_Hardware_.28OSHW.29_Definition_1.0
[URL]