A vehicle lane departure warning method and system with real-time error correction capability

Abstract

The present application relates to a kind of vehicle lane departure warning method with real-time error correction capability, comprising the following steps: step one, determine detector ranging frequency;Step two, establish collection section interval;Step three, assess running trend;Step four, set alarm real-time error correction mechanism;Step five: establish early warning condition.The present application has vehicle lane departure warning method with real-time error correction capability, by high-frequency ranging to the vehicle passing through detection section, real-time assesses the state and running trend of vehicle keeping lane, estimates the time that vehicle may occur traffic accident;When vehicle exists the risk of lane departure and collides with guardrail or drives out of road, different sound and light alarm prompts are taken according to its degree of lane departure or the length of time that traffic accident may occur, to remind driver to correct vehicle driving track, greatly reduce the occurrence of traffic accident.

Description

Technical Field

[0001] This invention belongs to the field of traffic engineering, and specifically relates to a vehicle lane departure warning method and system with real-time error correction capability. Background Technology

[0002] Existing lane departure warning strategies include the TLC (Time to Lane Crossing) method, the CCP (Car's Current Position) method, and a combined lane departure warning strategy based on CCP and TLC.

[0003] However, regardless of the algorithm or strategy mentioned above, the underlying assumptions of "1. the vehicle is a rectangular prism under the condition, 2. the vehicle's driving state remains unchanged" differ significantly from the actual traffic conditions. This leads to the detection results of the vehicle's driving state not representing the true results (e.g., if the vehicle is not a rectangular prism under the condition, the local detection distance of its external outline does not represent the actual distance between the vehicle and the roadside). The real-time adjustment of the vehicle's driving state cannot be reflected in the above warning strategies (e.g., the real-time adjustment of the vehicle's trajectory contradicts "the vehicle's driving state remains unchanged"). As a result, the above strategies have a high false alarm rate and poor real-time error correction capabilities.

[0004] Therefore, there is an urgent need for a vehicle lane departure warning method with real-time error correction capabilities to ensure road traffic safety and improve the accuracy of warnings. Summary of the Invention

[0005] To address the aforementioned problems, this invention proposes a vehicle lane departure warning method and system with real-time error correction capabilities.

[0006] This invention relates to a vehicle lane departure warning method with real-time error correction capability, comprising the following steps:

[0007] Step 1: Determine the detector ranging frequency

[0008]

[0009] In the formula, d f —Detector ranging frequency, times / s; v speed —Speed ​​limit on roads, m / s; l v —Vehicle length, in meters; —The floor function;

[0010] Step 2: Establish the sampling section interval

[0011] The detector placement interval is:

[0012] d s ≤v speed t r

[0013] In the formula, d s —Detector placement interval, m; t r —Driver reaction time, between 0.7 and 1.0 seconds;

[0014] Step 3: Assess operational trends

[0015] Based on the ranging results of adjacent detectors for the same vehicle and the same data acquisition sequence, the vehicle's running trend can be predicted:

[0016]

[0017] In the formula, L i,j —The distance measurement result of the i-th detector for the j-th vehicle, m; d s —Detector placement interval, m; θ—Offset angle, °;

[0018] Step 4: Set up a real-time alarm correction mechanism

[0019] To avoid false alarms, the following real-time trend correction mechanism and absolute value alarm real-time error correction mechanism are set up:

[0020]

[0021]

[0022] a i =a i +1,if L i,j ≤L s

[0023] In the formula, ct ij —Estimated time, s, for collision with guardrail or exiting the road after the j-th distance measurement at detector i; t i,j —The time s of the j-th distance measurement by the detector at the i-th location of the same vehicle; L s —Absolute value warning standard value, m; w i —Trend warning coefficient; a i —Absolute value warning coefficient;

[0024] Step 5: Establish early warning conditions

[0025] Condition 1: When a i ≥v threshold And the current ranging result L i,j ≤L s When a i ≥v threshold And the current ranging result L i,j ≤L s When the temperature reaches -0.5, an emergency alarm with sound and light will be activated.

[0026] Condition 2: When w i ≥v threshold And the current ct ij When w ≤ 5, the alarm light will turn on to indicate the alarm; when w i ≥v threshold And the current ct ij When the time is less than 2, an emergency alarm with sound and light will be activated.

[0027] In step one, to avoid using local test results to represent the overall operating status of the vehicle, it is necessary to ensure that each vehicle is tested no less than 5 times when passing through the test section.

[0028] In step two, the driver's reaction time is 1 second.

[0029] In the formula of step three, j takes a fixed value of 2; L i-1,2 >L i,2 Predicting vehicle movement trends in real time; when L i-1,2 ≤L i,2 If the prediction is abandoned, θ = 0°.

[0030] In step four, the coefficient a i and w i The threshold determination method is as follows:

[0031]

[0032] In the formula, v threshold —Alarm threshold; when w i ≥v threshold When one of the conditions for issuing a warning is met, the vehicle must reset its warning status after passing through. i =0; when a i ≥v threshold When one of the conditions for triggering an absolute value warning is met, the vehicle must reset option a after passing through. i =0; when the car leaves the i-th detector w i a i The warning threshold has not yet been reached; w needs to be reset. i =0, a i =0.

[0033] The present invention also relates to a system for implementing the method, the system comprising a data acquisition subsystem, a data evaluation subsystem, and an early warning subsystem.

[0034] Beneficial effects

[0035] The present invention provides a vehicle lane departure warning method with real-time error correction capability. By measuring the distance of vehicles passing through the detection section at high frequency, the method assesses the vehicle's lane-keeping status and driving trend in real time and estimates the time when a traffic accident may occur. When there is a risk that a vehicle may deviate from its lane and collide with the guardrail or leave the road, different audible and visual alarm prompts are given according to the degree of lane deviation or the length of time when a traffic accident may occur, reminding the driver to correct the vehicle's driving trajectory and greatly reducing the occurrence of traffic accidents. Attached Figure Description

[0036] Figure 1 This is a schematic diagram illustrating the working principle of the present invention. Detailed Implementation

[0037] The following combination Figure 1 This implementation method will be described in detail.

[0038] The vehicle lane departure warning method with real-time error correction capability of the present invention includes the following steps:

[0039] Step 1: Determine the detector's detection frequency

[0040] To avoid using local detection results to represent the overall operating status of vehicles, it is necessary to ensure that each vehicle is detected at least 5 times when passing through the detection section. Therefore, the detection frequency of the traffic flow detector must meet the following requirements:

[0041]

[0042] In the formula, d f —Detector ranging frequency, times / s; v speed —Speed ​​limit on roads, m / s; l v —Vehicle length, in meters; —The floor function.

[0043] A typical car is 4.5m long. Taking a highway with a speed limit of 120km / h (33.33m / s) as an example, the detector's detection frequency should be no less than 37 times / s. This embodiment assumes the detector's detection frequency is 100 times / s, i.e., d f =100 times / s, greater than 37 times / s, meets the requirements.

[0044] Step 2: Establish the sampling section interval

[0045] To achieve full coverage of vehicle lane departure assessment, continuous traffic flow detectors, such as video detection, are recommended. However, video detection suffers from low distance detection accuracy and threshold calibration drift. To save costs while still meeting basic full-range assessment requirements, the spacing of discrete detectors should meet the following requirements:

[0046] ds ≤v speed t r

[0047] In the formula, d s —Detector placement interval, m; t r —Driver reaction time is generally between 0.7 and 1.0 seconds. Given the significant differences in reaction time among different individuals, it is recommended to take 1 second. The meanings of other parameters are the same as above.

[0048] Taking a highway with a speed limit of 120 km / h (33.33 m / s) as an example, the required spacing between detectors should be less than 33 m. In this embodiment, laser rangefinders are deployed at 10 m intervals, i.e., d s =10m, which meets the requirements.

[0049] Step 3: Assess operational trends

[0050] Based on the ranging results of adjacent detectors for the same vehicle and the same data acquisition sequence, the vehicle's running trend can be predicted:

[0051]

[0052] In the formula, L i,j —The distance measurement result of the i-th detector for the j-th vehicle, m; d s —Detector arrangement interval, m; θ—Offset angle, °. In practical applications, j is taken as a fixed value of 2 here. Only L i-1,2 >L i,2 Only then can the vehicle's operating trend be predicted; while when L i-1,2 ≤L i,2 If the prediction is abandoned, set θ = 0°.

[0053] Assuming the vehicle is traveling at the speed limit (33.33 m / s), and the second distance measurements taken by two adjacent detectors are 1.72 m and 1.66 m respectively, then the vehicle's deviation angle is 0.344°. If the second distance measurements taken by two adjacent detectors are 1.72 m and 1.76 m respectively, then the vehicle has no risk of colliding with the guardrail or going off the road, and θ = 0°.

[0054] Step 4: Design an alarm real-time error correction mechanism

[0055] To avoid false alarms caused by inaccurate individual test results, false alarms even after the vehicle's deviation has been corrected during the test, or false alarms caused by further aberration of the vehicle's deviation, the following real-time correction mechanism for operating trends and real-time error correction mechanism for absolute value alarms are established:

[0056]

[0057]

[0058] a i =a i +1,ifL i,j ≤L s

[0059] In the formula, ct ij —Estimated time, s, for collision with guardrail or exiting the road after the j-th distance measurement at detector i; t i,j —The time s of the j-th distance measurement by the detector at the i-th location of the same vehicle; L s —Absolute value warning standard value, m; w i —Trend warning coefficient; a i —Absolute value warning coefficient; the meanings of other parameters are the same as above.

[0060] Assuming the vehicle travels at the speed limit (33.33 m / s), the second distance measurements taken by two adjacent detectors are 1.72 m and 1.66 m respectively, with a time difference of 0.31 s. When the second and third distance measurements taken by the detector after (1) are 1.66 m and 1.66 m respectively, then ct i3 =8.56s, that is, according to this running trend, it will collide with the guardrail or drive off the road 8.56s after the third detection time point; when the distance measurement results of the detector in the second and third times after (2) are 1.66m and 1.65m respectively, then ct i3 =2.37s; when the distance measurement results of the detector for the second and third times after (3) are 1.66m and 1.68m respectively, then ct i3 = -2.08s, ct i3 A value less than 0 indicates that the vehicle will not collide with the guardrail or run off the road if it continues in this direction.

[0061] After the third distance measurement in cases (1), (2), and (3) above i The results are 2, 2, and 1 respectively. If L s =1.66m, the first distance measurement result is 1.64m, then in the above cases (1), (2), and (3), after the third distance measurement, a i The results are 3, 3, and 2 respectively; other conditions remain unchanged, if L s =1.65m, then after the third distance measurement in cases (1), (2), and (3) above, a i The results were 1, 2, and 1 respectively.

[0062] coefficient a i and w i The threshold determination method is as follows:

[0063]

[0064] In the formula, vthreshold —Alarm threshold; the meanings of other parameters are the same as above. When w i ≥v threshold If the condition for a trend warning is met, the vehicle must be reset after passing through. i =0; when a i ≥v threshold If the absolute value warning is triggered, one of the conditions for the vehicle to pass must be reset (a). i =0; when the car leaves the i-th detector w i a i Even if the warning threshold has not been reached, w still needs to be reset. i =0, a i =0.

[0065] Assuming the vehicle travels at the speed limit (33.33 m / s), and other conditions remain unchanged, we can determine v. threshold =3.

[0066] Step 5: Establish early warning conditions

[0067] Condition 1: When a i ≥v threshold And the current ranging result L i,j ≤L s When a i ≥v threshold And the current ranging result L i,j ≤L s When the temperature reaches -0.5, an emergency alarm with sound and light will be activated.

[0068] Condition 2: When w i ≥v threshold And the current ct ij When w ≤ 5, the alarm light will turn on to indicate the alarm; when w i ≥v threshold And the current ct ij When the time is less than 2, an emergency alarm with sound and light will be activated.

[0069] Assuming the above conditions remain unchanged, L s =1.66m, after the 5th distance measurement a i =3, L i,5 = 1.28m. Since 1.16 < 1.28m < 1.66m, the alarm light will be activated. If the fifth distance measurement result L... i,5 =1.07m, since 1.07m < 1.16m, then the audible and visual alarm will be activated for an emergency warning; if the result of the 5th distance measurement is L i,5 =1.67m. Since 1.67m > 1.66m, there is no need to activate the audible and visual alarm for the time being.

[0070] Similarly, if w is measured after the 5th distance measurement i=3 and ct i5 =3.27s, because w i ≥3 and ct i5 ≤5, activate the alarm light; if w after the 5th distance measurement i =3, ct i5 = 1.46s, because w i ≥3 and ct i5 If the value is less than 2, an emergency alarm with sound and light will be activated; if the value is less than 2 after the 5th distance measurement... i =3, ct i5 =8.67s; although w i ≥3 but ct i5 >5. There is no need to enable the audible and visual alarm for the time being.

[0071] The above description of the present invention is only a preferred embodiment of the present invention and is not intended to limit the implementation of the present invention. Those skilled in the art can easily make corresponding modifications or alterations based on the main concept and spirit of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of protection claimed in the claims.

Claims

1. A vehicle lane departure warning method with real-time error correction capability, characterized by, The method comprises the following steps: Step 1: determining the detection frequency of the detector where d f — detector ranging frequency, Hz; v speed — road speed limit value, m / s; l v — vehicle length, m; — floor function; Step 2: determining the interval of the collected sections The interval of the detector arrangement is: d s ≤v speed t r In the formula, d s Detector arrangement spacing, m; t r - Driver reaction time, between 0.7 and 1.0 s; Step 3: evaluating the running trend Based on the detection results of the same vehicle and the same collection sequence by adjacent detectors, the running trend of the vehicle is predicted: In the formula, L i,j The mth ranging result of the ith detector to the same vehicle d s Detector arrangement spacing, m; θ - angle of deviation, °; Step 4: setting the alarm real-time correction mechanism In order to avoid false alarms, the following running trend real-time correction mechanism and absolute value alarm real-time correction mechanism are set: a i = a i + 1, if L i,j ≤ L s In the formula, ct ij — The estimated time of the ith detector after the jth ranging of the crash barrier or driving out of the road, s; t i,j — the time of the jth ranging of the ith detector of the same vehicle, s; L s - absolute value warning criterion value, m; w i —trend alert coefficient; a i —absolute value alert coefficient; Step 5: determining the early warning condition Condition 1: when a i ≥ v threshold and the current ranging result L i,j ≤ L s , turn on the alarm light; when a i ≥ v threshold and the current ranging result L i,j ≤ L s -0.5, turn on the audible and visual alarm for emergency prompt; Condition two: when w i ≥ v threshold and current ct ij ≤ 5, turn on the alarm light prompt; when w i ≥ v threshold and current ct ij < 2, turn on the sound and light alarm emergency prompt.

2. The vehicle lane departure warning method with real-time error correction capability of claim 1, wherein, In step 1, in order to avoid using local detection results to represent the overall running state of the vehicle, it is necessary to ensure that the detection frequency of each vehicle passing through the detection section is not less than 5 times.

3. The vehicle lane departure warning method with real-time error correction capability of claim 1, wherein, In the formula in step three, j is fixed at 2; L i-1,2 > L i,2 When L i-1,2 ≤ L i,2 , the prediction is abandoned, and θ = 0°.

4. The vehicle lane departure warning method with real-time error correction capability of claim 1, wherein, In step four, the coefficient a i and the threshold value of w i are established as follows: where v threshold is the warning threshold; when w i ≥ v threshold , one of the conditions for a warning is reached, and w i must be reset to 0 after the vehicle has passed; when a i ≥ v threshold , one of the conditions for an absolute value warning is reached, and a i must be reset to 0 after the vehicle has passed; when the vehicle has left the i-th detector, w i , a i must be reset to 0 if the warning threshold has not been reached. i i ​​ 5. A system for implementing the method for vehicle lane departure warning with real-time error correction capability according to any one of claims 1 to 4, characterized in that, The system comprises a data collection subsystem, a data evaluation subsystem and an early warning subsystem.

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