GPS For The Blind — Forgive Me If I Throw A Little Cold Water

GPS navigation plan to help blind

By Geoff Adams-Spink
Age & disability correspondent, BBC News website

Easy Walk is available on Symbian mobile phones

An Italian technology company is pioneering a GPS satellite system that will give blind people greater independence and mobility.

The Easy Walk service has been developed by Il Village, a firm in Turin in northern Italy.

It is currently being tested by a group of 30 people from the Italian Blind Union who are providing feedback. The plan is for Easy Walk to be launched to blind and partially sighted people in Piedmont in the autumn.

Easy Walk uses a mobile phone that runs the Symbian operating system, a small Bluetooth GPS receiver, text to speech software called Talks (though rival products are also compatible) and a call centre that will operate around the clock seven days a week….

“What is really important is that behind all that stuff there is a call centre with a human being that can help you and who understands your needs,” he said.

The system has already been tested across the border in France and Switzerland.

The first phase of the project has resulted in 95% accuracy in determining a user’s exact location and Mr de Paoli intends to rebuild the system from scratch for the second phase of testing to achieve 100% reliability. Read the full BBC article here:

I’m already on record as strongly supportive of all technologies to help those less abled, and certainly the blind. In fact just about a year ago I note I wrote a piece on this same subject where I wrote about old friends Thom Foulks (RIP) and Bonnie Snyder, two of many whom I used to spend a lot of time with thinking up ways to assist people with technology. This is still one of my favorite subjects. However, I also am a long-time GPS practioner and the term “Can’t make a silk purse out of a sow’s ear” comes to mind.

I applaud Mr. de Paoli’s efforts but I’d like to bring a couple points to his attention as well as to Mr. Adams-Spink, who as a reporter for an agency as English as the BBS News ought to know more about precision of language … especially when people’s hopes and dreams may be riding on your reportage.

First, let’s look at the tools here. GPS phones are notoriously inaccurate. When I was selling inexpensive commercial-grade tracking systems I had lots of queries and clients whose first experience with GPS had been with cheap mobile phones. They loved the promise of the technology but hated the sloppy application. Mobile phone GPS positioning is designed around the FCC E-911 requirements of locating a caller within 100 meters. Would you be confident of walking 100 meters in city traffic with your eyes closed? naw, didn’t think so. Blind folks could really use something like this but city sidewalks are often only a meter or so wide. This is a very high accuracy application and sadly it can’t be done with peanut vendor equipment.

Second, and yes I did notice, Mr. de Paoli is using a secondary add-on GPS receiver. I don’t know the brand or specs but let’s assume it’s at least up to standard commercial grade accuracy of about 10 meters, plus or minus, 95% of the time. This will help, but certainly not solve the accuracy problem. In addition it adds significant expense, battery life issues (two batteries to worry about charge in, and how many, like me, have a mobile phone that goes from showing full charge to dropping dead in a call in 3 or 4 minutes)? I also have yet to see a Bluetooth connected device that works as reliably as I would want to see a piece of personal safety-related gear work, but I’m not a Bluetooth expert.

Not addressed at all is the question of the antenna in the GPS and how it is going to be carried so it gets a clear and consistent view of the sky? I’d mount it on the top of of a baseball cap myself, but perhaps that’s too simplistic.

The last point I’d like to address is the technical detail of the story. When Mr. Adams-Spink says the system is currently 95% accurate in determining a user’s “exact” location, even a nit-picker like me will agree, given we don’t get too hung up on the definition of “exact”. But then, for no discernable reason, he relates how the developer plans to make the system 100% “Reliable”. My comment to that, after I recovered my breath and cleaned up the mess caused by snorting coffee out my nose is, “Good luck”!

No system made by man is 100% “reliable” and no system is 100% “accurate. When specifying systems involving aviation and space-based assets, such as GPS, is to define them in terms of RAM … not the Random Access Memory in your computer but Reliability, Availability and Maintainability. Reliability is typically the MTBF (Mean Time Between Failures) and index of the expected hours, days or months between breakdowns. I don’t think many of us have seen a mobile phone with an infinite time between failures any time lately, have we? Maintainability typically measures time to effect repairs so we don’t need to go into that here, as we know how long it takes to repair consumer-grade electronics like this, in technical terms it’s from now to whenever.

That leaves Availability … Availability rate = (total time – unavailable time) / total time. The total GPS availability, with all ground and spaced based redundancy doesn’t attain 100%, so obviously a tiny subset of the system with no inherent redundancy can’t do any better. I’m at a loss as to what the reporter really meant to say, but a person educated and gifted enough to work for a prestigious organization like the BBC should certainly know the meaning of TANSTAAFL.