Global Positioning System (GPS) is a space based satellite navigation system that provides location and time information whenever there is an unobstructed line of sight for four (or more) GPS satellites. Although it is the main positioning system used nowadays, there are times when it is not possible to reach GPS satellites, such as within (really) big cities, inside buildings, underground, etc.
Inertial Navigation Systems (INS) on the other hand, is a navigation system that uses motion (accelerometer) and rotation (gyroscopes) sensors to continuously calculate via dead reckoning the position, orientation and velocity of an object without the need of any external reference.
The purpose of the BikeNav project would be to implement an INS system using smartphones for bicycles and evaluate the reliability of this approach. The main goal is to have an INS system capable of keeping the real time navigation when the GPS signal is lost. In order to achieve that this system must be able to keep track of the user orientation (heading), through the gyroscope and magnetometer available in the smartphone. Additionally, the system must also be able to detect accelerations, in order to keep track of the users speed.
The first practical application of BikeNav is helping the African Community Health Workers (CHW) on their daily job, in the context of Syndromic Surveillance project. These agents are chosen by the community to provide basic health and medical care in developing countries. CHWs can drive bicycles for more than 25km a day moving between isolated populations. The Syndromic Surveillance requires CHWs to collect clinical data using mobile devices in scenarios of failure/low coverage mobile networks. The data needs to be related to Geo-location and earth observation from satellite data. Syndromic Surveillance will allow detecting and predicting outbreaks or epidemics, through the analysis of correlated data.
CHWs are indeed the main agents of the Syndromic Surveillance and their mission needs to be performed by bicycles in the countries of Sub-Saharan Africa, with the following challenges:
> Dense forests or mountainous regions as barriers to the reception quality of GPS signal;
> GPS not always can be assisted by failing 3G networks, which leads to lower accuracy and longer time for location lock;
> Near real-time positioning tracking is crucial since each clinical data collected should be associated with GPS coordinates;
> Low precision positioning of 500 – 1.000m2 is an acceptable requirement for our client, since this is the maximum resolution of their Earth Observation software.
Author: Cristiano Rodrigues
Type: MSc thesis
Partner: Faculdade de Engenharia da Universidade do Porto