My experience with the North Paw
For anyone unfamiliar with the North Paw, it is a haptic compass that is worn around the ankle. You can get more info about it here: http://sensebridge.net/projects/northpaw/
I was really excited about the North Paw, as a haptic compass (ideally an internal one, like the South Paw, but we obviously aren't there yet) and therefore a constant and reliable sense of direction has been my dream since I first read about haptic belt experiments in 2004 or 2005.
I got a North Paw and wore it for about three days before deciding that, while the concept is interesting, it is not reliable enough to continue to use in its current form. But, this may partially be due to my own usage pattern. YMMV.
First off, North Paw pros:
- Surprisingly good battery life. After a full charge, it easily lasted a full day of being out and about and was still going when I took it off after about 12 hours.
- Despite looking like a house arrest anklet, it's actually pretty discreet and can be easily hidden under a pant leg, providing you aren't wearing skinny jeans.
And, the big con:
- Usually, for me, it didn't buzz towards North. I only wore it in neighborhoods I'm familiar with while testing, and my city has a pretty well aligned grid, so it was super easy to tell when the North Paw was wrong. Which was most of the time.
I think the main reason the North Paw didn't work for me is that my primary means of transportation is by bike. Coincidentally, the way you calibrate a North Paw is by flipping it over four times. Often, while I was riding my bike, the pedaling motion would apparently trigger this calibration process, causing it to miscalibrate. It is also possible that the metal in the bike gears was throwing off the compass. But, a haptic compass that doesn't work while riding a bike is effectively useless to me, as that is the main time I need to have a good sense of direction. These things make me think that maybe the ankle is a poor location choice for a haptic compass (though probably still better than most other options, which change on more axises even more frequently). The waist might be the right place for such a wearable (and hopefully, one day, implantable).
Another strange thing is that apparently some buildings I frequent (notably the building my office is in, which also manages to act like a giant faraday cage and block out cell phone signals [related? who knows?]) will predictably cause the North Paw to signal a false positive "North". Since my phone compass agrees with this incorrect North, it's clearly the building's fault and not the North Paw's. Still, this makes me question the utility of a perma-compass in general, as its trustworthiness would immediately be suspect whenever you're indoors.