Vehicle lamp cooperative projection control method for severe weather

Abstract

The invention discloses a car lamp cooperative projection control method for severe weather, and belongs to the technical field of car lamps. The method comprises the following steps: S1, acquiring the speed of a vehicle, and environment information and road images in front of the vehicle; s2, environment information in front of the vehicle is evaluated, and if it is judged that the weather is low-visibility weather, a severe weather penetration mode is started; and S3, after the severe weather penetration mode is started, a lane line image and a safe vehicle following distance line image are projected to the road surface in front of the vehicle. The invention provides a vehicle lamp cooperative projection control method for severe weather, which can project a lane line image and a safe vehicle following distance line image to a road surface in front of a vehicle so as to solve the problem of unclear view of a driver caused by a light curtain effect in foggy, rainy and snowy weather in the prior art.

Description

Technical Field

[0001] This invention relates to a method for coordinated projection control of vehicle lights in adverse weather conditions, belonging to the field of vehicle lighting technology. Background Technology

[0002] Currently, modern vehicles are generally equipped with high-performance lighting systems, such as LED or laser headlights, to improve visibility while driving at night. However, in adverse weather conditions such as fog, rain, and snow, the strong light emitted by these headlights is severely scattered by water droplets or ice crystals in the air, forming a "light curtain" in front of the driver. This light curtain effect significantly reduces the contrast of the headlight projection image, making it difficult for the driver to see the actual road conditions and increasing safety hazards.

[0003] Existing ADB technology can partially solve the problem of glare from oncoming vehicles, but its core function is still to optimize the distribution of the illumination beam, without fundamentally solving the problem of light source scattering in adverse weather conditions. Existing DLP projection technology has also been attempted for road sign projection, but its core digital micromirror device (DMD) has limitations in heat resistance and low optical efficiency, which restricts its performance in scenarios requiring extremely high brightness to penetrate adverse weather conditions.

[0004] Therefore, there is an urgent need for an innovative solution that can overcome the above-mentioned shortcomings and provide drivers with clear and intuitive road information prompts in adverse weather conditions. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a vehicle headlight cooperative projection control method for adverse weather conditions, which can project lane lines and safe following distance lines onto the road surface in front of the vehicle to solve the problem of unclear driver vision caused by light curtain effect in foggy, rainy and snowy weather in the prior art.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: A method for vehicle headlight cooperative projection control in adverse weather conditions includes the following steps: Step S1: Collect vehicle speed, environmental information in front of the vehicle, and road images; Step S2: Assess the environmental information in front of the vehicle. If it is determined to be low visibility weather, activate the severe weather penetration mode. Step S3: After activating the severe weather penetration mode, project lane line images and safe following distance line images onto the road surface in front of the vehicle.

[0007] Furthermore, the environmental information includes visibility information and road ambient brightness.

[0008] Furthermore, in step S2, the environmental information in front of the vehicle is evaluated. If it is determined to be low visibility weather, the severe weather penetration mode is activated, specifically including the following steps: A visibility assessment model is established, and the expression of the visibility assessment model is as follows: ; Where V is the current estimated visibility ahead of the vehicle; L is the distance to the visibility sensor baseline; P0 is the emitted light intensity of the transmitter of the visibility sensor; P L The received light intensity of the visibility sensor's receiver after attenuation over distance L; K is the visibility sensor calibration constant; Real-time monitoring of P0 and P L The current visibility estimate V is calculated using the expression of the visibility assessment model, and then the current visibility estimate V is compared with a preset visibility threshold V. th Compare; If V≤V th If the visibility is low, the severe weather penetration mode will be activated.

[0009] Furthermore, in step S3, projecting lane line images and safe following distance line images onto the road surface in front of the vehicle specifically includes the following steps: Step S31: Adaptive brightness control is performed on the projected lane line image and safe following distance line image using a projection brightness control model. Step S32: Based on the real-time driving status, use the safe following distance model to calculate the position of the safe following distance line.

[0010] Furthermore, the expression for the projection brightness control model in step S31 is: ; Among them, L p The brightness of the lane line image and the safe following distance line image; L b ΔL represents the ambient light level of the road ahead of the vehicle. min (R) is the minimum brightness difference that the human eye can distinguish at an observation distance R; k is the adjustment coefficient; V is the estimated current visibility in front of the vehicle; V max L1 represents the baseline clear visibility; L2 represents the brightness adjustment gain.

[0011] Furthermore, the expression for the safe following distance model in step S32 is: ; Among them, D safeThe safe following distance line is the position of the vehicle, v is the current speed of the vehicle, and t is the position of the vehicle. r The sum of the driver's reaction time and the vehicle's braking system response time, μ is the road adhesion coefficient, g is the acceleration due to gravity, and D is the acceleration due to gravity. buffer For a safe buffer distance.

[0012] By adopting the above technical solution, this invention separates the functions of road floodlighting and road information prompts. In severe weather, a preset algorithm determines whether to activate the severe weather penetration mode. When activated, it projects high-brightness, highly directional lane lines and safe following distance lines onto the road surface in front of the vehicle, fundamentally avoiding visual interference caused by light source scattering. This provides drivers with intuitive road spatial relationships and warnings of following hazards, significantly improving drivers' road awareness and driving safety. Attached Figure Description

[0013] Figure 1 This is a flowchart of the vehicle headlight coordinated projection control method for severe weather according to the present invention; Figure 2 This is a schematic diagram showing the position of the safe following distance line according to the present invention. Detailed Implementation

[0014] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0015] like Figure 1 As shown, this embodiment provides a vehicle headlight cooperative projection control method for inclement weather, which includes the following steps: Step S1: Collect vehicle speed, environmental information in front of the vehicle, and road images. Environmental information includes visibility information and road ambient brightness. The vehicle's visibility information is detected by an onboard visibility sensor, lane line images of the road ahead are captured by an onboard forward-facing camera, and road ambient brightness is collected by an onboard light sensor. The vehicle's real-time speed is obtained via the vehicle's CAN bus.

[0016] Step S2: Assess the environmental information ahead of the vehicle. If low visibility weather is determined, activate the severe weather penetration mode. Specifically: A visibility assessment model is established, and its expression is as follows: ; Where V is the current estimated visibility ahead of the vehicle; L is the baseline distance of the visibility sensor, in meters, representing the fixed distance between the transmitter and receiver of the visibility sensor; P0 is the emitted light intensity of the transmitter of the visibility sensor, and also serves as a reference value for the received signal strength; P L The received light intensity of the visibility sensor's receiver after attenuation over distance L; K is the visibility sensor calibration constant, obtained through laboratory calibration.

[0017] Real-time monitoring of P0 and P L The current visibility estimate V is calculated using the expression of the visibility assessment model, and then the current visibility estimate V is compared with the preset visibility threshold V. th In comparison, the visibility threshold V in this embodiment... th The preset length is 200 meters according to national standards. If V ≤ V th If the visibility is low, the severe weather penetration mode will be activated.

[0018] The visibility assessment model in this embodiment is based on the estimation of meteorological optical range, and the formula used is as follows: ; Where V is the current visibility estimate in front of the vehicle, representing the current atmospheric visibility conditions; ε is the human eye's contrast perception threshold, which is usually set to 0.05 (i.e. 5%). σ is the atmospheric extinction coefficient, which represents the attenuation of light per unit path length due to scattering and absorption. In foggy or hazy weather, scattering is the dominant factor.

[0019] Based on the above formula, for ease of sensor measurement and calculation, an equivalent form is adopted, namely the expression of the visibility assessment model: .

[0020] Step S3: After activating the severe weather penetration mode, lane line images and safe following distance line images are projected onto the road surface in front of the vehicle. By projecting the lane line images onto the road surface in front of the vehicle, clear lane line indications are provided to the driver. Simultaneously, safe following distance lines are projected onto the road surface in front of the vehicle, constantly reminding the driver to maintain a safe distance from the vehicle in front, based on the position of the safe following distance lines. Specifically: Step S31: Adaptive brightness control is performed on the projected lane line image and safe following distance line image using a projection brightness control model.

[0021] To ensure optimal visibility of the projected lane line and safe following distance lines under varying ambient brightness, while avoiding glare from excessive brightness, the brightness of the projected images needs to be adaptively adjusted. The projection brightness control model in this embodiment is based on the contrast requirements between the target and the background, and its expression is as follows: L p = L b+ΔL min (R); Among them, L p The brightness of the lane line image and the safe following distance line image; L b ΔL represents the ambient light level of the road ahead of the vehicle. min (R) is the smallest difference in brightness that the human eye can distinguish at an observation distance of R.

[0022] In intermediate vision conditions, i.e., typical nighttime driving scenarios, ΔL min (R) does not perfectly follow the simple Weber's Law, which is expressed as follows: ΔI / I = K; Wherein, ΔI is the difference threshold, which is the minimum stimulus increment that can cause a sensory difference; I represents the original stimulus intensity; K is a constant called the Weber ratio or Weber fraction, which indicates that people are more sensitive to changes in stimuli in different sensory channels.

[0023] In other words, there's a psychological principle governing people's perception of brightness: in dim environments, subtle changes in light are easily noticed; while in bright environments, more significant changes in light are required to attract attention. However, the actual situation is more complex, and the expression for the real-world scenario is as follows: ; Where a, b, and c are empirical fitting or calibration parameters, describing the nonlinear change in human eye contrast sensitivity with the brightness of the road environment ahead of the vehicle. For example, when the brightness of the road environment ahead of the vehicle is typically 0.1–10 cd / m² during nighttime driving, a = 0.1, b = -0.5, and c = 0.02. R is the observation distance in meters, which can be approximated as the image projection distance.

[0024] Considering the atmospheric transmittance T(R) = exp(-σR), the actual image brightness reaching the human eye is... Therefore, to ensure visibility, the required initial projected brightness L p _ req Compensation is required; the initial projected brightness L after compensation p _ req The expression is as follows: .

[0025] Combining this with the visibility assessment model, the final projection brightness control formula is obtained: ; Among them, L p The brightness of the lane line image and the safe following distance line image; L bΔL represents the ambient light level of the road ahead of the vehicle. min (R) represents the minimum brightness difference that the human eye can distinguish at an observation distance R; k is the accommodation coefficient, indicating the different sensitivities to changes in stimuli across different sensory channels; V is the estimated current visibility ahead of the vehicle; V max Define the starting point or zero point for brightness adjustment based on the baseline clear visibility or maximum design visibility, when the actual visibility V ≥ V max At that time, the weather was considered to be excellent, so the brightness adjustment term in the formula was invalid, and the projection brightness only needed to meet the basic contrast requirements; L0 is the brightness adjustment gain, which determines the intensity of brightness adjustment as visibility changes. Together with the adjustment coefficient k, it forms a brightness amplifier. The worse the visibility, the smaller the visibility estimate V, and the higher the output compensation brightness.

[0026] Lane lines and safe following distance lines can be projected using long-wavelength light sources such as amber, which have lower scattering intensity in fog and rain than short-wavelength blue and white light, and thus better penetration characteristics.

[0027] Step S32: Based on the real-time driving status, use the safe following distance model to calculate the position of the safe following distance line.

[0028] The position of the safe following distance line needs to be dynamically calculated based on real-time driving conditions, using the following kinematic model: ; Among them, D safe To maintain a safe following distance, D thinking For the reaction distance, D braking D is the braking distance. buffer For a safe buffer distance.

[0029] Reaction distance D thinking This refers to the distance of delayed braking, which is the sum of the driver's reaction time and the vehicle's braking system response time.

[0030] ; Where v is the vehicle's current speed, derived from the vehicle's CAN bus; t r This is the driver's reaction time plus the vehicle's braking system response time. The driver's reaction time is typically 1.2-1.5 seconds, and the vehicle's braking system response time is typically 0.2-0.3 seconds, totaling approximately 1.5-1.8 seconds.

[0031] Braking distance D braking This refers to the distance a vehicle travels from the moment maximum braking force is applied until it comes to a complete stop. It is a purely physical distance, without taking into account the driver's perception, judgment, and reaction time.

[0032] ; Where v is the vehicle's current speed, obtained from the vehicle's CAN bus; μ is the road adhesion coefficient, which is affected by road material (asphalt, cement), condition (dry, wet, ice), and tire condition. It can be estimated by on-board sensors such as the ESP system or by the driver selecting a preset mode, such as μ=0.8 for dry road surface and μ=0.4 for wet road surface; g is the acceleration due to gravity, 9.8 m / s².

[0033] Safety buffer distance D buffer This is an additional distance added to the sum of the reaction distance and braking distance. Its main purpose is to provide a safety margin to cope with uncertainties that may occur in actual driving. Uncertainties include, for example: Sensor errors and measurement uncertainties: There may be errors in the measurement of parameters such as speed, distance, and road surface adhesion coefficient.

[0034] System response delay: The minute delay between the vehicle control system issuing a command and the actual braking action.

[0035] Uncertainty regarding the behavior of the vehicle in front: The vehicle in front may suddenly apply more urgent braking.

[0036] Changes in vehicle condition: Vehicle load, braking system efficiency, tire wear, etc., may affect the actual braking distance.

[0037] Environmental factors: The road surface friction coefficient may change during braking, for example, when moving from wet asphalt to ice.

[0038] Finally, the expression for the safe following distance model is: ; Among them, D safe The safe following distance line is the position of the vehicle, v is the current speed of the vehicle, and t is the position of the vehicle. r The sum of the driver's reaction time and the vehicle's braking system response time, μ is the road adhesion coefficient, g is the acceleration due to gravity, and D is the acceleration due to gravity. buffer For a safe buffer distance.

[0039] like Figure 2 As shown, if the vehicle speed v = 80 km / h, the road surface adhesion coefficient μ = 0.4, the driver's reaction time + the vehicle braking system response time tr = 1.6s, and the safe buffer distance D... buffer =5m. Substitute into D safe The expression is used to calculate D. safe =103.4m.

[0040] A safe following distance line is projected 103 meters in front of the vehicle. The driver can constantly observe this line while driving. If the safe following distance line is too close to the vehicle in front or has already collided with it, it indicates that the following distance is at a dangerous level.

[0041] The specific embodiments described above further illustrate the technical problems, technical solutions, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for vehicle headlight cooperative projection control in adverse weather conditions, characterized in that, It includes the following steps: Step S1: Collect vehicle speed, environmental information in front of the vehicle, and road images; Step S2: Assess the environmental information in front of the vehicle. If it is determined to be low visibility weather, activate the severe weather penetration mode. Step S3: After activating the severe weather penetration mode, project lane line images and safe following distance line images onto the road surface in front of the vehicle.

2. The vehicle headlight coordinated projection control method for severe weather as described in claim 1, characterized in that, The environmental information includes visibility information and road ambient brightness.

3. The vehicle headlight coordinated projection control method for severe weather as described in claim 1, characterized in that, In step S2, the environmental information in front of the vehicle is assessed. If it is determined to be low visibility weather, the severe weather penetration mode is activated, which specifically includes the following steps: A visibility assessment model is established, and the expression of the visibility assessment model is as follows: ； Where V is the current estimated visibility ahead of the vehicle; L is the distance to the visibility sensor baseline; P0 is the emitted light intensity of the transmitter of the visibility sensor; P L The received light intensity of the visibility sensor's receiver after attenuation over distance L; K is the visibility sensor calibration constant; Real-time monitoring of P0 and P L The current visibility estimate V is calculated using the expression of the visibility assessment model, and then the current visibility estimate V is compared with a preset visibility threshold V. th Compare; If V≤V th If the visibility is low, the severe weather penetration mode will be activated.

4. The vehicle headlight coordinated projection control method for severe weather as described in claim 3, characterized in that, In step S3, projecting lane line images and safe following distance line images onto the road surface in front of the vehicle specifically includes the following steps: Step S31: Adaptive brightness control is performed on the projected lane line image and safe following distance line image using a projection brightness control model. Step S32: Based on the real-time driving status, use the safe following distance model to calculate the position of the safe following distance line.

5. The vehicle headlight coordinated projection control method for severe weather as described in claim 4, characterized in that, The expression for the projection brightness control model in step S31 is: ； Among them, L p The brightness of the lane line image and the safe following distance line image; L b ΔL represents the ambient light level of the road ahead of the vehicle. min (R) is the minimum brightness difference that the human eye can distinguish at an observation distance R; k is the adjustment coefficient; V is the estimated current visibility in front of the vehicle; V max L1 represents the baseline clear visibility; L2 represents the brightness adjustment gain.

6. The vehicle headlight coordinated projection control method for severe weather as described in claim 5, characterized in that, The expression for the safe following distance model in step S32 is: ； Among them, D safe The safe following distance line is the position of the vehicle, v is the current speed of the vehicle, and t is the position of the vehicle. r The sum of the driver's reaction time and the vehicle's braking system response time, μ is the road adhesion coefficient, g is the acceleration due to gravity, and D is the acceleration due to gravity. buffer For a safe buffer distance.

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