Development of Advanced Idle Stop-and-Go Control Utilizing V2I 2020-01-0581
Idle Stop-and-go (ISG), also known as Auto Stop/Start, is a fuel saving technology common to many modern vehicles that enables the engine to shut down when the vehicle comes to a stop. Although it may help with fuel efficiency, many drivers in the North American market find the feature to be an annoyance due to hesitation in vehicle re-launch and engine shudder during stop or restart. This paper introduces the usage of traffic signal phase and timing (SPaT) information for controlling the activation of ISG with the goal of reducing driver complaints and increasing acceptance of the function. Previous studies proposed the utilization of Advanced Driver Assistance System (ADAS) to introduce adaptability in powertrain controls to traffic situation changes. For instance, when a vehicle stops and the engine shuts off, the controller monitors the movement of the preceding vehicle using ADAS sensors and restarts the engine when the front launches, prior to the driver releasing the brake pedal. The control logic can also utilize the traffic sign recognition function of the vision sensor to inhibit ISG under specific driving conditions where the feature is typically undesirable, for example, while stopped at a stop sign or waiting at a roundabout. However, when the vehicle is first in line at a traffic light, the previously suggested method for engine restart based on movement detection becomes useless because there is no target vehicle ahead to follow. Thus, the new control logic proposed in this paper leverages Vehicle-to-Infrastructure (V2I) communication for engine restart out of ISG. By obtaining the SPaT of a traffic light, the engine can be restarted a couple of seconds before the traffic light turns green without having to observe a preceding vehicle’s movement. Two methods for obtaining SPaT information were investigated. The first used a smart phone connected to a traffic information server via a 4G LTE network, and the second used Dedicated Short Range Communication (DSRC). Both of these methods showed that this advanced control strategy provides readiness for forthcoming vehicle launch, which may promote acceptance of the ISG function. The description of the new control logic is discussed, and the validation results acquired through real-world vehicle tests are demonstrated.