oblu - a shoe-mounted Indoor Positioning Device
Have you ever wondered that it would have been great if GPS technology could have been used inside big airport or large shopping mall? You often struggle to find your gate number in big International airport. You spend a lot of time on finding the right store you want to visit in a big shopping mall. How can you beat the long search for your destination indoors? Indoor Positioning and navigation has become very important to the people in the last decade and half due to setting up of huge shopping malls, airports etc where a person easily get lost. Advancement in different technologies also paved the way to tackle indoor navigation problem head on.
What is an indoor positioning system and why do we need them?
According to Wikipedia “An indoor positioning system (IPS) is a system to locate objects or people inside a building using radio waves, magnetic fields, acoustic signals, or other sensory information collected by mobile devices.”
IPSes use different technologies, including distance measurement to nearby anchor nodes (nodes with known positions, e.g. WiFi access points or Bluetooth beacons), magnetic positioning, pedestrian dead reckoning. They either actively locate mobile devices and tags or provide ambient location or environmental context for devices to get sensed.
We spend nearly 70% of our time indoors. Therefore, there are many applications which require indoor navigation of humans and machines. The most commonly used positioning solution is satellite based GPS/GNSS which is good for outdoor navigation. It fails in indoor environment or in urban environment which are not accessible to the clear sky. Thus necessitates a indoor positioning system for applications such as geo-survey of slums or the areas under heavy tree canopy, indoor navigation of robots, positioning of rescue agents' for fire fighting, mining accidents, urban warfare etc.
There are many indoor positioning technologies but IMU based Pedestrian dead reckoning (PDR) is one of easiest and cheapest technology to use as it infrastructure free. Here comes “oblu”, a shoe-mounted indoor GPS device.
So what is oblu?
oblu is an Arduino compatible, miniaturized, low cost and open source inertial sensor targeted towards wearable motion sensing applications. It provides you a platform to construct and implement your own thoughts. You are free to configure it as per your need.
The feature rich motion sensor comes pre-programmed as a shoe-sensor (Pedestrian Dead Reckoning or PDR sensor) which is highly effective for navigation under a heavy tree canopy or in the urban locality surrounded by concrete buildings & trees or inside buildings where GPS gets iffy.
The Pedestrian Dead Reckoning (PDR) system consists of "oblu" as a shoe-sensor (IMU) and a PDR application, say Xoblu Android App. Data from on-board multiple IMUs are sampled, fused, calibration compensated and undergoes navigational computation to produce displacement and orientation information of foot at every step. The "oblu" transmits displacement and orientation data at every step to Xoblu, in response to an appropriate command. Xoblu then, using this PDR data from the "oblu", constructs and displays real-time tracked path.
The PDR application is shown below:
The multi-IMU along with the complex-motion-processing-inside approach not only improves accuracy, but also simplifies data transmission to user platform. The PDR data, i.e. displacement and heading change, is transmitted at every step in a very simple format. Data transmission frequency matches with the step frequency which is typically 1 Hz for normal walk. Thus the low rate PDR data (typically few tens of bytes per second) reduces chances of transmission losses as well. The PDR data also removes computation burden from the application platform. The integration between oblu and application platform is shown below:
The modular approach relaxes constraints on the integration platform, allows application engineer to focus on incremental innovation and significantly reduces time-to-market.
Here is the diagram showing the indoor navigation path as traced by its Android Application Xoblu:
What the advantages of oblu are in compared with other IPS?
As it was mentioned above that there are many technologies for indoor positioning. So why we need oblu then? Unlike other popular indoor navigation device, oblu is an infrastructure free device. So there is no need to have some infrastructure preinstall in any indoor environment. You can use oblu practically anywhere in the world. You just put it on your shoe and you are good to go. This significantly reduces setup time. Another important application of infrastructure free indoor positioning is for rescue operation / military operation where one cannot expect any preinstall infrastructure. Thus making it very unique and cheap for such applications. For more details about different indoor positioning technologies one may have look at this article.
Positioning and navigation using Smartphones are very beneficial in everyday life. Where would we be without the friendly voice of Google maps which shows us the way wherever we are? But alas it cannot help us indoors.With oblu there are possibilities to put such an affordable “indoor GPS” into practice.
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