When will smartphones be able to navigate to a few metres of accuracy indoors?
Over the past few years the ability of consumer grade devices, typically smart phones but also PNDs, to navigate indoors has improved significantly. This is because GPS has been supplemented by other navigation technologies, such as cell tower identification and, more recently, navigation using Wi-Fi to localise position.
To get reliable sub-10metre accuracy indoors, however, will require more than GPS, cellular and Wi-Fi positioning. Use of other sensors, particularly MEMS inertial sensors, as a compliment to the existing positioning information is likely to provide the answer.
MEMS sensors are becoming very common on consumer devices. For example they are used to detect movement, orient screens and stabilise images. The most common sensors are accelerometers, gyroscopes and magnetometers. In vehicles, odometry (wheel pulse) is also commonly used. Other inputs to a navigation solution include barometric pressure measurement (to help determine height, such as which floor of a building) and even cameras and light sensors.
The answer to accurate indoor position, accurate enough to locate a car in a parking garage or a shop in a mall, would seem to lie in integrating as many of these sensor inputs as possible to provide a blended position.
How far away is this? I would suggest 3-5 years. If you have a different view, let us know.