Contribution to orientation aids for the visually impaired using GPS, magnetometer, barometer and Inertial Measurement Unit
We have evaluated the possibilities and the limitations of different sensors able to help to the orientation of the visually impaired: GPS, magnetometer, gyroscope, accelerometers, and barometers and also the way to mix their information for guiding efficiently the visually impaired in three different contexts: urban areas, hiking and indoor areas. We have implemented some belt mounted and hand held prototypes giving the information in the way of “heading” and “distance” to the destination to reach. This information is updated in real time taking into consideration the change of the position and orientation of the person. We have shown, during real situation tests, in urban pedestrian paths and hiking circuits of many kilometers done by different visually impaired people, the efficiency of this approach which is very different to the car navigation. The tests have been run including zones where the sensors data is perturbed: dense forest or big buildings in urban areas (GPS signal perturbed), proximity to electrical lines (magnetometer data perturbed), etc. The most complicated case is the indoor navigation (metro stations and commercial centers) where the GPS signal is not available. Our approach does not require any equipment apparatus in the building (such as Bluetooth or Wi-Fi hotspots) and uses just a previous cartography or a cartography done in situ. We have achieved functional guidance in few hundred meters under certain conditions: the training of the user in order to make him understand the specific characteristics of the mobility language used for the navigation and the learning of the strategies of displacement in order to avoid the failure of the Inertial Measurement Unit (IMU). We are in position to offer, at the end of this work, one tool which can be distributed to the users with reliable solutions for the urban areas and the hiking. For the indoor navigation, complementary development is carrying on and it will be proposed just like beta-test version. This tool is also going to be proposed for initiating non-autonomous visually impaired people to easy treks in order to try to make them want to improve their autonomy.