Exploitable results
Reposit has:
- studied user needs and application requirements, producing a 'System Requirements' deliverable;
- developed algorithms and produced an integrated simulator for V2V communications, RGNSS positioning and CAS warnings;
- run simulations on the scenarios that were defined (72 tests on each software version);
- analysed the feasibility of in-vehicle integration, including the deliverable 'Reposit in-vehicle integration';
- established a certification and standardisation policy, including a business plan and a CEN Workshop Agreement (CWA).
A key achievement was the software development and the final results extracted from the simulation phase. The software modules were developed to simulate each technology involved in Reposit (Relative GNSS positioning, V2V communications and CAS) and a mainstream code comprises the required function calls and synchronism among modules, tying the overall Reposit simulator as a whole. Therefore every simulated vehicle inherits a standard logical architecture and all vehicles are properly synchronised to the millisecond level thanks to the PPS pulse signal received from the GNSS receiver, and they interchange data through the communication module.
The vehicle-to-vehicle/vehicle-to-infrastructure (V2V/V2I) communication module developed allows inter-vehicular communications providing the required data transfer capabilities for a relative positioning algorithm that works in real-time. The data types devised to be interchanged among vehicles are GNSS raw data of approximately 1kb length per vehicle at 1Hz to compute GNSS relative algorithms, and Alarm data warning in advance to all nearby vehicles after a critical red alarm is detected.
A RGNSS (Relative Global Navigation Satellite System) module takes and processes as input the raw data provided by the GNSS receiver on-board a vehicle and the raw data received from other vehicles in real-time through the communication channel.
The trialled system was found to have sufficient accuracy for lane detection (across-carriageway) and properly detects the collision time instant (along the carriageway).
A Collision Avoidance System (CAS) Module was developed, which takes the relative positioning information provided by the RGNSS module as inputs, as well as the information received from other vehicles through the V2V communication link. With this information it predicts the relative dynamics of the vehicles on the road, and it also can advance if a collision is to happen in the near future. When such an event is foreseen, an alarm is raised for the user to be aware of a dangerous situation that might evolve quite fast.
Finally, a Human-Machine Interface (HMI) was developed of a Reposit system based on providing initially visual and acoustic cues to the driver to warn him of any upcoming threat to his safety.
Reposit was a concept and feasibility activity, so Certification needs to be achieved prior to any use for road traffic. Therefore feasibility of standards approval and of Certification according to well defined, institutionally accepted rules is a condition for Reposit feasibility.
Reposit has demonstrated its potential on highways and linear scenarios, but it is still a challenge for it to be effective on continuously changing roads. The system has to count on additional future information to anticipate the changing conditions or increase the monitoring frequency to minimise error peaks, and both initiatives are affordable at low cost by using available maps for such extrapolation and low cost GNSS receivers. So the system has to evolve to face these new challenges using cooperative systems, and remaining a cost effective product. Also, it has to wait until V2V becomes a reality to prove its value in different environments. However, Reposit is still feasible and will potentially show how GNSS systems can tell us more than just our location.
The Reposit system is analogous with a current navigation system within a vehicle but with a V2V communication and additional software running at the background, so it is mainly software, and due to this, cost effective. Perhaps the most expensive part would be the wholly in-vehicle Reposit installation linked with the dashboard HMI, so a strategy could be to leave Reposit to be also installed externally, thus making it affordable.
Recommended future work is the development of a demonstrator system using real vehicles, in order to prove simulations against real world situations.
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