Indoor Location Sensing

[d7x]

I've got an application that requires indoor positioning and was wondering how applicable the Ultimate GPS - https://www.adafruit.com/products/746 - might be. My understanding is that GPS units require line of sight to satellites but I've also seen some GPS units seem to acquire location while inside. To be more specific, I want to know where the object is (X & Y coordinates only, for now) in relation to a central point within the building. If the Ultimate GPS cannot be relied upon for indoor location sensing, what type of components would you recommend using?

[franklin97355]

Describe the building, the size and the resolution you need. Does this have to work while the object is moving? RFID may be what you need

[d7x]

The main location will be a 28,000 sqft exhibit hall. In regards to whether the object will be stationary, no it will be mobile. Given that it's mobile, it needs to know where "home" is so that it doesn't stray from an area that's 5 sqft.

The secondary location will be a 1 or 2 story house.

[adafruit_support_bill]

it needs to know where "home" is so that it doesn't stray from an area that's 5 sqft.

That's less than a 1 meter radius. Even in ideal conditions, GPS won't give you that level of accuracy.

[d7x]

Are there any other types of solutions that would allow an object to communicate with a nearby base that would provide either relative or absolute location? For example, would it be possible to:
1) emit a signal that the mobile object could pick up a code
2) use the strength of the signal to calculate the distance

Out of curiosity, does Adafruit sell any components that could be used for #1, #2, or both?

[adafruit_support_bill]

The XBee modules do have a relative signal-strength indicator. With more than one transmitter and some triangulation logic, you might be able to estimate relative position. But radio-signal propagation in interior spaces can be hard to predict.

There are a lot of other options including: infrared, ultrasonic, RFID, compass, gyro, accelerometer and odometry. The ideal solution really depends on the functional requirements and operating environment. Such a solution most likely will include some combination of the above technologies.

[franklin97355]

There is an article in the March 2012 issue of Circuit Cellar by Larry Foltzer on "Position Determination from Acoustic Delay Triangulation" that might be what you need. IR beacons are another possibility.

[EasternStarGeek]

Exhibit halls are usually set up on plain concrete floors that are covered with carpet, dividers, etc. when the decorators come in to set up. You might be able to set up a wire-guided AGV system in an environment like that. Tape the wire down to the floor before the carpet is put down. Possible in theory- check with the venue manager and the exhibit coordinator. Naturally, they will want to collect an extra fee if they can.

Hope you're not trying to do this at the Javits Center.

[d7x]

I've decided to add a couple of constraints to the project for the application in an exhibit hall in which I would simply program movements within a small area.

But, my other application is one in which the bot might be in a structure with multiple rooms and would need to have "memory" of different location to know which areas to avoid. The goal is to avoid certain areas of a building while seeking out other areas of a building. To determine the approximate location, RFID sounds like it could be a good technology to leverage if an RFID chip can be read from a distance of a few feet. I'm thinking that 2 chips on either side of a hallway could suffice to alert the bot that the area is off limits.

1) Does this sound feasible with passive RFID or would active RFID be worth a look?

2) Or, is there a better technology that could be leveraged for this purpose?

[adafruit_support_bill]

There are some longer range passive RFID technologies that could work in that envoronment.