Solution for lane departure warning system based on ISO17361 standard

LDW (According ISO17361)

1. Definition

Warning threshold

The position of the vehicle on the road when the alarm is issued corresponds to the alarm trigger point set inside the system.

warning threshold placement zone

The area between the earliest alarm line and the latest alarm line, within which the alarm threshold is set.

Curve cutting is a driving behavior that can lead to intentional lane departure and driving toward the inside of the curve.

Chinese lane parameters (refer to GB5768_1999'Road traffic signs and markings'):

Lane width: between 3.0m and 3.75m.

Lane width: 10, 15 or 20 cm.

Lanes of different directions: 4 m (solid line) + 6 m (empty);

Lane lines in the same direction: 2 m (solid line) + 4 m (empty) for urban roads; 6 m (solid line) +9 m (empty) for expressways.

2. Example diagram

3. System functional requirements and classification

4. Test basic scenarios

4.1 Test environment conditions

The following test environmental conditions were employed.

a) Test location: dry and flat asphalt or concrete road surface;

b) Test temperature range: -20℃～40℃;

c) Visible lane markings on the test road surface should be in good condition and comply with the requirements of GB5768.

d) Horizontal visibility should be greater than 1 km.

4.2 Test lane conditions

The radius of curvature of the test lane should be within ±10% of the minimum radius of curvature of the corresponding type in Table 1. The test lane should be long enough to meet the minimum operating speed requirement (i.e. 20m/s for Type I and 17m/s for Type II), so that the vehicle can leave the lane at a departure speed of 0m/s﹤v ≤0.8m/s.

4.3 Test vehicle conditions

The mass of the test vehicle should be between the total mass of the vehicle's curb weight plus the driver and test equipment (the total mass of the driver and test equipment shall not exceed 150kg) and the maximum allowable total mass. The description of the mass should comply with the requirements of 3.2 of GB/T3730.2-1996. The conditions of the test vehicle are not allowed to be changed after the test begins.

4.4 Test system installation and setup

The installation and setting of the lane departure warning system shall be carried out in accordance with the equipment instructions provided by the manufacturer. For the testing of the lane departure warning system with user-adjustable warning thresholds, each test shall be carried out twice, i.e. once with the warning threshold set at the earliest warning threshold and once with the warning threshold set at the latest warning threshold. It is not allowed to change the system settings after the test has started.

4.5 Test Output

Parameters obtained from the data record The following parameters are obtained from the data record:

 a) Alarm trigger point (time and/or space);

 b) deviation speed;

 c) Vehicle speed.

The test equipment records all alarm information during the test and obtains the required parameters from it.

testing scenarios

ØScenario 1: Alarm generation test

The vehicle should be basically in the center of the lane at the beginning of the test. When the vehicle enters the test lane for tracking and reaches a stable state, the vehicle can gradually deviate to the inside and outside of the curve. The vehicle's curve speed is selected according to the system classification in Table 1, that is, 20m/s~22m/s for Type I and 17m/s~19m/s for Type II. The vehicle should deviate once to the left and once to the right in two deviation speed ranges (0.0m/s~0.4m/s and 0.4m/s~0.8m/s) in both right and left turns. Eight deviation conditions can be combined, as shown in Table 3 and Figure 5.

table 3

Figure 5 Alarm test method

ØScenario 2: Repeatability test

Repeatability testing should be conducted on a straight road section. The vehicle speed is selected according to the system classification in Table 1, 20m/s~22m/s for Type I system and 17m/s~19m/s for Type II system. The vehicle can drive along the center of the lane, or drive close to the lane marking on the other side opposite to the lane marking that the vehicle is about to deviate from and cross. For example, if the lane is about to deviate to the right, the vehicle can drive along the lane marking on the left, and vice versa, as shown in Figure 6. After the vehicle tracks along the test lane at the specified speed and reaches a stable state, the vehicle can gradually deviate to the left and right sides of the lane. When the deviation speed is 0.1m/s﹤（V1±0.05）≤0.3m/s, two groups of eight tests are conducted (four left deviations in the first group and four right deviations in the second group); when the deviation speed is 0.6m/s﹤（V2±0.05）≤0.8m/s, another two groups of eight tests are conducted (four left deviations in the third group and four right deviations in the fourth group), that is, a total of 16 tests are required. V1 and V2 are pre-selected by the equipment manufacturer. The test system should be tested sequentially in groups (four tests per group) according to the deviation speed shown in Table 4.

Table 4

Figure 6 Repeatability test method

ØScenario 3: False Alarm Test

The test lane is a straight road with a total length of 1000m (one straight road with a length of 1000m or two straight roads with a length of 500m). When the vehicle is driving in the non-alarm area, the system should not issue an alarm and record the system alarm situation.

Test pass criteria:

ØAlarm generation test 

In each test, the system should ensure that the alarm is issued after the vehicle crosses the earliest alarm line and before crossing the latest alarm line.

ØRepeatability test

For each test group, the system alarm threshold should always be located within a fixed area of ​​0.3m width. When the vehicle is outside the alarm threshold setting area, the system should not issue an alarm. If a test group includes more than 4 tests, and all are within the corresponding deviation speed range, only the first 4 tests are considered.

ØFalse Alarm Test

When the vehicle is between the two earliest warning lines on the left and right (i.e., non-warning area), the system should not issue an alarm.