HIGH ACCURACY VEHICLE GEOLOCATION WITH ABSOLUTE REPOSITIONING, ENSURING EXCELLENT RELIABILITY AND AVAILABILITY
The positioning of a vehicle using GPS is marred by availability problems (areas without GPS coverage such as tunnels, underground car parks) or by significant positioning errors (particularly around urban areas causing reflection of GPS paths). SYSNAV’s trusted navigation solution responds to these issues by supplementing or correcting these errors. As a key principle of SYSNAV’s solutions, no false position, wrongly indicated as reliable, can arise. Reliability and availability are ensured by a set of complementary sensors that constitute a tactical range system with coupled technologies. In addition, this system makes it possible to permanently remove all typical positioning issues:
- Over shooting
- Positioning delay
- Unavailability indoor or underground (service road, tunnel, garage, hangar, etc)
The principle of dead reckoning navigation is that the distance traveled at each instant is projected into the local geographic axes (Up / Down, North / South, East / West). The distance traveled is obtained from the merged measurements of several sensors:
- L’MIMU’s accelerometers (Magneto-Inertial Measurement Unit)
- L’MIMU’s magnetometers
- Data from the wheel odometer
This redundancy ensures continuity of service and exceptional operational reliability. The heading is obtained from the navigation algorithm which uses the angular speeds measured by the gyroscopes and the aforementioned speed measurements. A Kalman filter supervises the data set and produces parameters used to derive the uncertainty on the estimated position.
When operating autonomously without GPS, the system delivers a solution with an accuracy of around 1% of the distance traveled. An accuracy of 5m is guaranteed at all times in nominal mode, even during loss or unreliability of the GPS signal for a certain time. To compensate for this derivation, the GPS is used by the filter as a repositioning means. The GPS measurement, when available, is compared to the navigation solution developed by the filter and is taken into account depending on the estimated quality of the reception and multiple paths encountered.
Both hot and cold start positionings are instantly available, especially for the use of vehicles parked indoors (i.e. firefighter trucks). In fact, the SYSNAV solution excels in reliability, availability and precision performance and can meet legislative requirements in a very competitive economic position.