Background
Since the mid-2000s, the global Automated Vehicle (AV) industry has invested more than $80 billion developing self-driving passenger, cargo, and industrial vehicles. Almost all of this research has assumed that other vehicles are manually driven. As a result, multi-vehicle maneuvers that ordinary human drivers trivially accomplish many times per day (such as highway merging, making unprotected left-hand turns, and navigating roundabouts) have only recently become possible for AVs, unnecessarily limiting safe applications of AV technology. The successful results of this project enabled AVs equipped with Connected Vehicle (CV) technology, called Connected Autonomous Vehicles (CAV)s, to perform these maneuvers safely and efficiently.
Approach
The system is composed of a CV subsystem, a negotiation subsystem, and an autonomy subsystem. SwRI's novel negotiation subsystem uses the CV subsystem and a state machine to manage the status of all the vehicles involved in the maneuver, requesting and organizing the maneuver at a high level. The autonomy system of each vehicle is tasked with controlling the vehicle and providing information to the negotiation subsystem about the vehicle’s ability to successfully participate in the maneuver. Control of the maneuver and negotiation is not centralized, and each vehicle in the maneuver interacts with the other vehicles to determine their role in performing the maneuver. Each vehicle uses its route map in conjunction with sensors and data provided by the other vehicles to determine safe participation in the maneuver.
The research and development of this system was split into two phases. During Phase 1, the basic functionality and merging was developed. In Phase 2, the system was improved and adapted to stay within configurable application-specific comfort limits to ensure passenger comfort. Data collections were performed to evaluate if the system was able to stay within those limits.
Accomplishments
The three main possible merging scenarios were performed successfully on three of SwRI's autonomous vehicles in both phases (see attached demonstration video). The experiment was executed at SwRI’s test track and involved performing a multi-vehicle merge at approximately 25 mph. Depending on the arrival time of each vehicle, the merging vehicle would merge in front of, between, or behind the other vehicles in the maneuver.