Testing and Analysis of Lane Departure Warning and Lane Keeping Assist System Response

Many new vehicles come equipped with Advanced Driver Assistance Systems (ADAS) as standard or optional features. These technology packages frequently include Lane Departure Warning (LDW), an electronic system designed to alert the driver when the vehicle begins to depart from its lane. These systems identify lane boundaries using computer analysis of video captured by a forward-facing camera, typically mounted near the rear-view mirror. Some vehicles are also equipped with Lane Keeping Assist (LKA). Upon detecting an unintended lane departure, LKA will make electronic steering and/or braking control inputs to keep the vehicle in its original travel lane. Four vehicles equipped with LDW and LKA were tested: a 2019 Toyota Corolla, 2019 Honda Civic, 2020 Ford Explorer, and 2019 Chevrolet Tahoe. Tests were conducted on a straight, flat road with clear lane markings. Lane departures to the left and to the right were initiated by the test driver at 45 and 65 mph. Using a VBOX 3i RTK DGPS, data related to the vehicle’s speed, acceleration, and driver- and software-related control inputs were collected via the vehicle’s CAN bus. Additionally, the VBOX collected vehicle location data of ±2 cm (±0.79 in) accuracy relative to survey points. Analysis of test data yielded details of system-level behaviors. For LDW, the average warning issue point (lateral distance prior to reaching the lane boundary) observed was 1.33 ft, the average rate of departure (lateral velocity) was 1.45 ft/s, and the warning occurred 0.76 sec before lane departure. Lane keeping actions began, on average, 1.13 ft from the lane boundary (0.66 sec before lane departure) and involved 4.81 degrees of steering with an average maximum lateral acceleration of 2.86 ft/s² (0.09 g). The LKA systems tested permitted the vehicles’ outside tires to exceed the lane boundaries by an average of 0.14 ft.