Lateral Controllability for Automated Driving (SAE Level 2 and Level 3 Automated Driving Systems) 2021-01-0864
In this study we collect and analyze data on how hands-free automated lane centering systems affect the controllability of a hazardous event during an operational situation by a human operator. Through these data and their analysis, we seek to answer the following questions: Is Level 2 and Level 3 automated driving inherently uncontrollable as a result of a steering failure? Or, is there some level of operator control of hazardous situations occurring during Level 2 and Level 3 automated driving that can reasonably be expected, given that these systems still rely on a driver as the primary fall back. The controllability focus group experiments were carried out using an instrumented MY15 Jeep® Cherokee with a prototype Level 2 automated driving system that was modified to simulate a hands-free steering system on a closed track with speeds up to 110kph. The vehicle was also fitted with supplemental safety measures to ensure experimenter control. The lateral controllability study was carried out with a specific focus group of 61 participants representing a demographic unbiased population. Results suggest that driver hand position (hands on/off the steering wheel) significantly moderates a driver’s ability to control and recover from unexpected erroneous steering torque events, and that performance is impacted by torque profile (magnitude and ramp). Evidence suggests that drivers are able to control and recover from sudden unexpected steering torque events as high as 1.7 Nm and 5 Nm/sec ramp as long as a single hand is on the steering wheel in the vehicle under test. This paper discusses various lateral controllability metrics, and provides recommendations for application in hazard analyses of Level 2 or Level 3 automated driving systems.