A Soiling Mitigation Method to Enhance the Performance of ADAS in Precipitation 2022-01-0076

The emergence of autonomous driving technology has tremendous mobility and social-economic benefits. Autonomous vehicles (AVs) rely on various sensors for environmental and traffic data. However, the sensor performance and reliability degrade in adverse weather conditions, which poses a challenge to the safety of AVs. Existing active mitigation strategies such as wipers and water jets are active, complex, and expensive to implement. This study investigated soiling mitigation via a passively rotating lens with the goal to maintain Advanced-Driver-Assistance-System (ADAS) sensor visibility in the rain. The concept of rotating lens has merely been lightly explored in the literature but never studied in detail with realistic continuous rain simulation to verify soiling mitigation effectiveness. An optical camera in place of a frontal vehicle ADAS sensor was integrated into a rotating lens for visual characterization. A wind tunnel was used to simulate various wind-driven rain scenarios in both urban and suburban driving speeds. As driving speed in rain increases, sensor reliability and performance exacerbate due to an increase in perceived rain characteristics, including angle and intensity. This investigation studied the correlation of the rotating lens angular velocity at different driving speeds and its effectiveness in mitigating soiling under various perceived rain conditions. The increase in angular velocity resulted in a direct increase in centrifugal force experienced by each raindrop present on the lens; hence, providing a mitigation effect when droplets are spun off. Compared to stationary reference lens, observations from mitigation-enabling rotating lens showed greatly improved clarity from the optical camera frontal view in reduction of environment obstruction and distortion from rain droplets. Image processing results suggested high confidence in combating all droplet sizes and driving-in-rain conditions. This investigation successfully demonstrated the effectiveness of rotating lens as a concept for soiling mitigation and provided insight for enhancing ADAS sensor performance and reliability in adverse weather conditions.