Harry Potter and the Infineon's Hallows

The world needs low cost and accurate indoor navigation system. Hospitals, museums and exhibitions, industrial facilities, automated warehouses etc.

Many universities have a very complex campus structure of several buildings with several floors. This is use case of using indoor and outdoor navigation simultaneously.

Some buildings can include several parts, each of which was built in different historical time. These parts were joined to the original building one by one in different manner, so that the indoor navigation in the whole building is very complicated. An example of such a building is St. Petersburg State University of Aerospace Instrumentation: five parts, four floors, more than 500 rooms.

The main aspect of indoor navigation is floor detection. It is a critically important part. Outdoor navigation has two main dimensions, system can make a mistake and point to the nearby house, in worst case nearby street: such mistake is not too critical. On the other hand, for indoor navigation all three dimensions are vauable. In this case of wrong floor detection can give to the user a completely wrong floor map and totally confuse him.

There is still no leading technology for indoor navigation today, especially in a low cost segment. GPS could not be used inside buildings. WiFi triangulation is complex and usually does not give required accuracy. Also, there could be some places inside the building without any WiFi signal at all. More information about technologies for indoor positioning were collected by as in this paper.

Moreover, it is a widely spread situation, when a building has some locations with very bad or even without mobile communication. Therefore, a reliable, autonomous solution for floor detection is needed.

Accuracy of Infineon's DPS310 pressure sensor allows detecting the exact floor and counting steps to make a precise positioning for indoor navigation.

Step 1. Floor detection with Infineon's pressure sensor

In the Barometric Pressure Sensing with Infineon video we can see various application scenarios including floor detection.

First, we had to make sure that we could get the required accuracy for floor detection for the particular building. To do this we installed Infineon Pressure Sensor Android app and successfully connected SensorHub Nano demo board via Bluetooth.

We run tests inside the building, measured characteristics and got the results which values precisely corresponded to each floor.

We also tried to count steps through rocking of a bracelet. This allows showing to the user her/his approximate positioning on the floor.

Step 2. Building a fully functional prototype

We designed a technology for rapid development of low-cost indoor-services and built an indoor navigation system for our university. It allows finding rooms and build routes between any two points (rooms, entrance, facilities). In this application the user has to change the map position while moving and change floors manually when the route reaches the stairs. Sometimes it is a problem, because the user even does not realize that floor should be changed. The reason is the complicated building architecture as in , where the stairs is a not a guarantee of floor changing.

It is time to change this situation with the Infineon's pressure sensor. :)

Using the Infineon API, we developed a program that allows the application on Android to receive pressure values from the Sensor Hub Nano board via Bluetooth.

Based on the receiving pressure values the application switches the UI to the appropriate floor.

The route is created after entering numbers of the initial and final auditorium or by scanning the QR code. In any case, it is well-known practice.

We assume that the user starts his movement from the starting point of the constructed route. We took the average length of the user's step as one meter. We are calculating the number of bracelet rockings, assuming that the user follows the route and thus, we can calculate its approximate location in the corridors.

The program calculates the traveled distance and highlight the corresponding part of the route.

As a result, we got a fully functional and tested prototype of indoor navigation system with automatic positioning and floor detection.

Future work

There are many things to improve to move from functional prototype to the final product.

First, the route must be completely traced so that the user understands where to go. We did not have time to implement the traversed route drawing over the top of the constructed one. This assumption can be seen in the video. In general, the routes are completely drawn from the auditorium to the auditorium (for example: http://purecreation.ru/suainavqr/?src=1129&dst=5214 ).

Second, we need to improve the accuracy of measuring the user's steps, as well as track its deviations from the route (for example, the user went to the toilet =)). With the help of additional external sensors (for example, compass), we can correct the oncoming errors:

- when the user reaches the corner of the corridor, the direction of his movement also changes (he goes to the right or to the left)

We can track the walk upstairs, which gives us another way to adjust - if the pressure changes no more than DELTA, then the user has finished walking upstairs and, in addition, we know the user’s position for further tracking of the route.

Using two ways to correct inaccuracy and the ability to track the number of user steps, we determine in which part of the university the user is located: a part, a floor, a place in the corridor.

Potential

We suppose that such systems have a great potential. If smartphone vendors integrate very accurate pressure sensors such as Infineon pressure module inside their products (smartphones, tablets) with third party developers they could create new opportunities for rich user indoor navigation experience solutions in various fields.

In addition, there are several other potential markets such as:

• Special devices for museums and exhibitions: navigation, audio guide, augmented reality etc. There is a big benefit to have prepared device and not to use the smartphone of the user. For example: independence from its battery level etc. As an option, special phone cases (with pressure and others sensors) could be made for the most popular models. Usage scenario: During standing on the line to buy the ticket the user puts his/her phone in the special case and install the application.

• Special devices for data centers service

• Special devices for building business needs