location sensing


What options are available to provide location specific information to visitors in museums? And how do these options compare? If you had to make a decision today, what technology would you choose? Well, it would depend on your objective and your budget.

As I’ve pondered these questions, I’ve come up with a list of what I consider to be the viable location sensing options today. This topic must be revisted at least once a year (preferably every 6 months) as the technology is changing quickly.

Location Sensing Options:

  1. Manual
  2. Infrared
  3. Bluetooth
  4. RFID
  5. GPS
  6. WiFi (802.11)
Rating Location Sensing Options
Manual Infrared Blue tooth RFID (short) RFID (long) GPS WLAN
Cost

None Low Low Low Medium Low Very High
Line of Site No Yes No No No Yes No
Range 10m 1m-10m 5-25cm 3-5m unlimited unlimited
Functions Indoors Yes Yes Yes Yes Yes No Yes
Energy Required on PDA None Low Low Low Medium Low High

Requirements of my current research:

  1. Indoors
  2. Able to handle 30-50 people simultaneously
  3. Ideal reading range – 1 to 3 meters
  4. Intuitive/transparent technology
  5. Low cost

GPS won’t work, because I’m indoors. I can’t afford to even consider Long Range RFID or WiFi at this time. This leaves me with four options to consider.

Manual User manually enters a code number to indicate their location.
Pros: Inexpensive and easy to implement. Allows you to pour all your resources into content creation and usability.
Cons: Users have to hunt for code numbers. Since most museums don’t have content for every object, users aren’t sure which items have additional content unless they get close enough to see the code number.

Infrared – Infrared triggers are placed in each area/room of the museum.
Pros: Simple technology. Low energy requirement. Inexpensive. Because infrared requires line of site, it insures location accuracy.
Cons: Requires line of site, so a crowded gallery can make sensing the triggers difficult. (this can be overcome by placing triggers on ceiling and using multiple triggers).

Bluetooth – Bluetooth triggers are placed in each area/room of the museum.
Pros: Low energy requirement. Inexpensive. Does not require line of site (works in crowded situations).
Cons: Bluetooth standards are still in flux. Maximum of 8 connections per pico net will require multiple triggers for 50 simultaneous connections. Can transmit through walls giving inaccurate location.

RFID – RFID passive tags are placed in each area/room of the museum.
Pros: Low energy requirement. Short range RFID SD Readers now available at reasonable price point.
Cons: Requires user to be within 1-4 inches of the tag.

My recommendations today for this research project:

  • Infrared triggers on the ceiling

My hopes for tomorrow:

  • Long Range RFID – I’m watching this technology closely and predict that this will be a reasonable solution within 1-2 years.

My humble opinion:

  • WiFi isn’t the best fit for location sensing today. I’ve got to have wifi in the museum for transfering data realtime, but the cost for accurate location sensing isn’t worth it. And before you know it, wifi will be as ubiquitous as mobile phone coverage, so spending large amounts of money on current 802.11 access points for location sensing isn’t the best use of resources.

I can’t wait to see what the landscape looks like in 6 months!

Position Puzzle: Where are you? Or more specifically, where is your handheld?

IrDA Beacon and Dell Axim x50v

One method for determining the location of a handheld computer indoors is by infrared beacons. Armed with two Lesswire IrDA Beacons and my trusty Dell Axim x50v, I searched for the answer to my position puzzle.

Each Lesswire IrDA Beacon is designed to broadcast a unique identification code over a short distance. In addition to the unique id, the beacon can hold up to 60 text strings. Maximum broadcast area for this unit is 10 meters with a wide angle coverage of 165 degrees horizontal and 55 degrees vertical. The unit can be powered by battery or external power supply.

So, for example, if you were to walk into a museum of natural science, I could have an IrDA Beacon in front of every major exhibit. Your handheld would sense the exhibits you were closest to and let you choose to learn additional information. I would have the choice of mapping the IrDA unique code to each exhibit, and triggering the appropriate information that way, or I could add a few text strings to communicate information to the handheld device.

For my first experience, how could I resist teaching the IrDA beacon to say “Hello” and “Glenda”. Original…I know.
Screenshot of PDA receiving Beacon ID and the text HelloScreenshot of PDA receiving Beacon ID and the text Glenda
Condensed Results

  • Pros: Works like a charm. I’m in love. IrDA is a wonderful option for location sensing. Economical, compared to wireless location sensing. Easy to set up and maintain.
  • Cons: Infrared requires line of sight, so beacon’s can be blocked by someone standing in front of it. Possible solution, mount multiple beacons for an exhibit, or mount beacon on ceiling where it isn’t likely to be blocked. Does not provide wireless internet access for other fun things I want to do in the museum.


Specific Lessons Learned about IrDA Beacons and Pocket PCs:

  1. For Windows Mobile 2003 OS: Make sure to install the iPAQ 5550 version of the lwBeacon.dll. This is the only dll that I’ve gotten to work with the Windows Mobile 2003 OS on the Dell Axim x50v and the Dell Axim X5.
  2. Make sure the “Receive Incoming Beams” setting is UNCHECKED. I know, I know…it sounds counterintuitive..but it is true.
    Settings>Connections>Beam
    (uncheck) Receive all incoming beams and select discoverable mode.

    Why do you need to do this? Because if you leave this setting checked, then the lwBeacon.dll and the Windows Mobile 2003 infared.dll fight with each other and you will never win!

  3. The wires that lead from the battery to the IrDA device were purposely not connected (I think to keep the device from draining the battery). Once I connected the wires…then the battery took a charge and voila, I was in business.
  4. While I could get my newer devices (Dell Axim X50v and X5) to receive the IrDA beams, I could NOT get them to reprogram the content on the IrDA beacon itself. I had to use an old iPAQ 3670 running MS PPC Version 3.0 to program the lesswire beacons. I couldn’t get any of the Dell’s (Windows Mobile 2003) to program the beacon. They Dell’s can all receive the beacon info…but not program it. Luckily, I’ve got about 5 old iPAQ 3670’s lyin’ around.

I have a new dance step to share with you. It is called the Ekahau Dance…and it goes like this.

  1. Set up at least 4 wireless access points.
  2. Install the Ekahau Position Software on one laptop and a few mobile devices (laptops or pdas)
  3. Mark a square grid out on the floor of the “room” you want to establish location sensing. Each point should be at least 5 feet from the other points.
  4. Turn on the Ekahau Position Software on your primary laptop and begin the dance
    • stand on grid point 1
    • with primary laptop in your hands (Ekahau software in “sensing mode”)
    • Do a smooth 360 degree turn while standing on grid point 1 in exactly 20 seconds
    • move to grid point 2 and repeat until you’ve danced on all the grid points
  5. You’ve just taught the Ekahau software what wireless access “smells” like at each grid point!
  6. Now, grab a mobile device (with the Ekahau client software installed) and walk around the “room”
  7. Abracadabra – your movements are shown on the primary Ekahau Laptop.

Notes to self for next Ekahau Dance Session: Wear cowboy boots (not sneakers or thongs) and bring iPod fully charged and loaded.

Why would I want to do the Ekahau Dance? Because I’m a handheld junkie? Noooooo, because I want to create a “smart environment” indoors. Imagine, being in a museum and having a handheld device that is sensitive to your location. Then the fun begins. I can’t wait to design this user interface, making sure that you are in control and that information is intuitively available to you, but never interrupts you.

The Ekahau Positioning Engine is my first 802.11b wireless location sensing experiment. I’m also exploring RFID, IrDA and Bluetooth. More on these adventures as they occur!

Where are you? That is the question o’ the day. With all of our mobile devices and wireless access…we can now find each other easily (when we want to be found), but interestingly enough, we rarely know where the other person is. And how often are you not quite sure where you are? Wouldn’t it be cool to have your very own Marauder’s Map? (Just in case you aren’t up on your Harry Potter..the Marauder’s Map is a magic map that shows the location of everyone in Hogwarts School of Witchcraft & Wizardry in real time).

Reality check, Goodwitch…there isn’t a real marauder’s map!
Why, I beg to differ. I’ve experienced it myself!
Do tell…

I’ve been researching location sensing with handheld computers and discovered some delicious off-the-shelf solutions. My first round of testing was with the Ekahau Position Engine which uses WiFi signal strength to sniff out your location and map you to the map. So, I’ve literally watched the motions of my teammates on my very own Ekahau/Marauders Map! Our early results have given us accuracy to within 6 inches (at best) and 22 feet (at worst). I’m looking forward to the next round of fine tuning which I hope yields accuracy of 3 feet or better. Why in the world would I want to accurately know where someone is? So, I could provide information to you (if you want it) based on your current location.

Museums Examples:

  • You are in a gallery in the museum and I can give you information on the works of art that are near you.
  • You’ve wandered off from the rest of your group and wonder where they are & vice versa.

College Campus Examples:

  • It is the first day of classes and you don’t know where your next class is.
  • You agreed to meet a friend on the west mall, but there is quite a crowd and you can’t locate them.

So, what would you like to know from your location sensitive PDA or Laptop? Would you want location based information? Do you like the idea of being able to see where someone is or allowing others to see where you are…or is it all a little too “big brother” for you?

Prediction: museums will be filled with transparent technology in the future…and not just technology for technology sake…but technology that makes the museum responsive to you.

Early example: Experience Music Project (EMP) in Seattle. Walk into a room at EMP, and your handheld computer senses where you are. Choose to listen to detailed information on the artist, music or genre…or just soak in the era by listening to the mp3 of your choice.

My favorite moments at EMP

  1. Wandering through the Jimi Hendrix display while listening to “Purple Haze”, “All Along the Watchtower” and “Fire”, I was transported to the 60’s. I never had the chance to hear Hendrix live…but for a moment…as I stood inches away from his guitar and his stage clothes with his music blasting in my ears…I was there.
  2. Roots and Branches sculpture of 500 guitars

    When I realized that the amazing “Roots & Branches” sculptureof over 500 musical instruments was actually playing live music robotically. The sculpture was art, music and math transformed into a jaw dropping collage of instruments and musical styles.

  3. Playing a little bass to “Louie Louie” in the Sound Lab….where instruments are programmed to help the novice (that’s me) or allow the experts to strut their stuff.
  4. EMP, you rock! You don’t just showcase your collection, you put the music in my hands and the spotlight on me. This is what I want all museums to be like…hands-on, interactive and personal.