A laser radar-based vehicle braking stability detection device and method

Abstract

The present invention relates to a vehicle road test braking performance detection device and method based on two-dimensional laser radar, which belongs to automobile safety performance detection equipment. The device mainly comprises: 2 laser radars of the same model, 2 columns and a signal acquisition and control system. The device uses two two-dimensional laser radars to scan the vehicle tires and bumpers respectively during the vehicle braking process, uses the gradient change law to obtain the effective curve, and processes to obtain the characteristic points. The braking information of the vehicle is obtained by tracking the characteristic points. The present invention can detect the road test braking performance of the vehicle without installing complex equipment. The method has a novel and unique design concept, good detection accuracy, simple device structure, and is easy to install and operate. The research results have certain theoretical and practical value and have a good prospect for application and promotion.

Description

Technical Field

[0001] The present invention relates to a vehicle road test braking performance detection device and method based on two-dimensional laser radar, which belongs to automobile safety performance detection equipment. The device uses two two-dimensional laser radars to scan the vehicle tires and bumpers respectively during the vehicle braking process, uses the gradient change law to obtain the effective curve, and processes to obtain the characteristic points. The braking information of the vehicle is obtained by tracking the characteristic points. The present invention can detect the road test braking performance of the vehicle without installing complex equipment. The method has a novel and unique design concept, good detection accuracy, simple device structure, and is easy to install and operate. The research results have certain theoretical and practical value and have a good prospect for application and promotion. Background Art

[0002] The longer the car is used, the worse the technical parameters will be. The quality of braking performance directly affects the main factor of vehicle safety. According to GB7258-2017: When there is doubt about the braking performance of a vehicle after bench testing, the road test specified in the standard can be used for re-inspection, and the test results of the full-load road test shall prevail. The road test braking test parameters include average braking deceleration, braking coordination time, braking stability and braking distance.

[0003] At present, the main instruments for intelligent road detection methods are the five-wheel instrument test method and the portable brake performance tester test method. The five-wheel instrument displays the running speed, braking time, braking distance and other parameters of the test vehicle in real time by adding "five wheels" to the side or tail of the car. However, this equipment is only used for vehicles with lower driving speeds and is affected by many factors during the test process. The portable brake performance tester uses the brake pedal contact switch as the starting signal and the acceleration sensor as the detection element. By processing the collected signals, parameters such as braking coordination time, initial braking speed, braking distance and average braking deceleration are obtained. However, complex equipment needs to be installed before the test, and the braking results are susceptible to errors caused by installation errors and the impact of vibration on the equipment during braking.

[0004] At present, there is no automobile road test braking performance testing equipment that is easy to install and has accurate and efficient testing. Summary of the invention

[0005] The main purpose of the present invention is to provide a vehicle road test braking performance detection device and method based on two-dimensional laser radar. The device has a unique design concept, is easy to install, and has strong repeatability.

[0006] The above-mentioned object of the present invention can be achieved through the following technical solutions, which are described as follows in conjunction with the accompanying drawings:

[0007] A vehicle road test braking performance detection device and method based on two-dimensional laser radar, the device includes a laser scanning device, a signal acquisition and control system, and is characterized in that:

[0008] The laser scanning device consists of two front and rear two-dimensional laser radars 2 and 9 of the same model and two front and rear pillars 4 and 7. The front and rear pillars 4 and 7 are installed on the right side of the detection area. With the vehicle's forward direction as the positive direction, the front-to-back distance between the center lines of the two pillars is m, and the range of m is 5 meters to 10 meters; the heights of the front and rear pillars 4 and 7 are l1 and l2 respectively, the range of l1 is 2 meters to 2.5 meters, and the range of l2 is 0.5 meters to 1 meter; the front and rear two-dimensional laser radars are respectively installed on the upper part of the pillars.

[0009] The front and rear two-dimensional laser radars 2 and 9 are fixedly mounted on the front pillar 4 and the rear pillar 7 respectively; the front two-dimensional laser radar 2 is fixed on the rocker arm 5 through the front radar fixing frame 3; the rear two-dimensional laser radar 9 is fixed on the L-shaped steel plate 6 through the rear radar fixing frame 10.

[0010] The laser emission points of the lasers 2 and 9 of the front and rear two-dimensional laser radars are A and B respectively. The distance between the laser emission point A and the ground is h1, h1=l1-0.5 (meters), and the distance between the laser emission point B and the ground is h2, h2=l2-0.3 (meters); the scanning plane of the front two-dimensional laser radar 2 forms an angle θ with the xoy plane (θ ranges from 20 degrees to 30 degrees), and the scanning plane of the rear two-dimensional laser radar 9 is parallel to the xoy plane; wherein, the xoy plane is a horizontal plane.

[0011] The front two-dimensional laser radar 2 establishes a coordinate system with the laser emission point A as the origin, the vehicle travel direction as the x-axis, the laser scanning direction as the y-axis, and the direction perpendicular to the ground as the z-axis; the rear two-dimensional laser radar 9 establishes a coordinate system with the laser emission point B as the origin, the vehicle travel direction as the u-axis, the laser irradiation direction as the v-axis, and the direction perpendicular to the ground as the w-axis.

[0012] The above detection device is used to detect the braking performance of the automobile road test:

[0013] When the vehicle starts to brake, the signal acquisition and control system 1 controls the front and rear two-dimensional laser radars 2 and 9 to start collecting information; the rear two-dimensional laser radar 9 scans the car tire during the vehicle braking process, obtains the effective data of the tire profile curve by using the gradient change law, and then fits the vehicle tire profile curve, fits the curve by using the nonlinear least squares method, and obtains the common tangent line and common tangent point of the fitting curve, iteratively calculates the matching degree of the two segments of data based on the common tangent point, and when the matching degree reaches the corresponding accuracy, the intersection of the symmetry axis of the two segments of the curve and the common tangent line is determined as the feature point; the front two-dimensional laser radar 2 scans the car bumper during the vehicle braking process, obtains the effective data segment by using the characteristics of the sudden change of the boundary point data, and fits the curve by using the nonlinear least squares method, and then obtains the centroid coordinates of the fitting curve, and obtains the braking distance and average braking deceleration of the car by tracking the centroid coordinate information;

[0014] Braking distance S measurement method:

[0015] When the vehicle starts braking, the signal acquisition and control system 1 controls the front two-dimensional laser radar 2 to start collecting data. The angle between the front two-dimensional laser radar 2 and the horizontal plane is θ. The point cloud information is obtained by scanning the car bumper. According to the characteristics of the sudden change of the boundary point data, the effective data is obtained. The curve is fitted using the nonlinear least squares method to obtain the centroid coordinates of the curve; suppose the reading of a data point N of the front two-dimensional laser radar is (ρ, α, θ), ρ is the distance value from the point to the laser emission center point A on the scanning plane, α is the angle value of the scanning laser beam passing through the measured point, and θ is the angle between the scanning plane of the front two-dimensional laser radar 2 and the horizontal plane. Then the spatial coordinates of the data point are

[0016]

[0017] Record the starting coordinates of the centroid point in the X-axis direction, recorded as X s When the braking is finished, record the coordinate of the centroid in the x-axis direction, denoted as X e , vehicle braking distance S = X e -X s ;

[0018] Braking stability detection method:

[0019] When the vehicle starts to brake, the signal acquisition and control system 1 controls the rear two-dimensional laser radar 9 to horizontally scan the position of the rear wheels of the vehicle to obtain the point cloud information of the rear tires.

[0020] A certain measured point M in the rear two-dimensional laser radar scanning plane is saved in polar coordinates as (ρ, α), where ρ is the distance from the point to the laser emission center B on the scanning plane, and α is the angle of the scanning laser beam passing through the measured point; the acquired point cloud data is converted to the rectangular coordinate system of the starting scanning plane, and the conversion formula is:

[0021]

[0022] Where C is a fixed constant.

[0023] The curve changing rule is analyzed based on the second-order derivative of the curve to extract the smooth changing segment of the tire profile curve and obtain the tire profile curve of the rear tire.

[0024] The nonlinear least square method is used to fit the curves and the common tangent line and common tangent point of the two curves are obtained.

[0025] Taking the common tangent point as the reference, take the same length on both sides to obtain two new data curves and perform matching analysis until the matching accuracy requirement is met; the symmetry axis is obtained about the common tangent line and the common tangent point, and the intersection of the symmetry axis and the common tangent line is the feature point.

[0026] By obtaining the coordinates of the feature point in the v-axis direction when the vehicle starts braking and the coordinates of the feature point on the v-axis after braking, the difference is the horizontal displacement of the vehicle.

[0027] Average braking deceleration MFDD detection:

[0028] The coordinate value X of the vehicle at time point t is obtained by the front two-dimensional laser radar 2 and the signal acquisition and control system 1. t After Δt time, the vehicle X coordinate value X is obtained. t+Δt , calculate the vehicle speed

[0029]

[0030] Calculate the fully developed average deceleration MFDD using the following formula:

[0031]

[0032] Among them, u b is the vehicle speed of 0.8u0 (km / h); u0 is the actual braking speed (km / h); u e The vehicle speed is 0.1u0 (km / h); s b From u0 to u b Distance traveled by the vehicle (m); s e From u0 to u e Distance traveled by the vehicle (m). BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Axonometric drawing of automobile braking performance testing device

[0034] Figure 2 Schematic diagram of the front and rear 2D laser radar coordinates

[0035] Figure 3 Schematic diagram of the front two-dimensional laser radar 2 scanning the vehicle body position.

[0036] Figure 4 Schematic diagram of the rear two-dimensional laser radar 9 scanning the vehicle body position.

[0037] Figure 5a Axonometric view of the front 2D LiDAR 2 scanning mechanism.

[0038] Figure 5b Axonometric view of the rear 2D laser radar 9 scanning mechanism.

[0039] In the figure: 1. Signal acquisition and control system, 2. Front two-dimensional laser radar, 3. Front radar fixing frame, 4. Front column, 5. Rocker arm, 6. L-shaped steel plate, 7. Rear column, 8. Square steel plate, 9. Rear two-dimensional laser radar, 10. Rear radar fixing frame DETAILED DESCRIPTION

[0040] The specific content and implementation modes of the present invention are described in detail below with reference to the accompanying drawings.

[0041] The present invention relates to a vehicle road test braking performance detection device and method based on two-dimensional laser radar. The device mainly consists of a signal acquisition and control system 1, two two-dimensional laser radars of the same model and two columns. The signal acquisition and control system 1 mainly includes an industrial control computer, an I / O input and output card and a 5375 optical isolation power amplifier output board. The industrial control computer model is EVOC IPC-810E, the CPU is E5300 2.6G, the memory is 2G, the hard disk is 500G, the I / O input and output card and the 5375 optical isolation power amplifier output board are both IPC series products; the two-dimensional laser radar is a German Sick brand LMS111-10100 electromagnetic excitation laser radar, with an output wavelength of 40mm and a line width of 20mm.

[0042] See also Figure 1 The present invention relates to a vehicle road test braking performance detection device and method based on two-dimensional laser radar. The device is mainly composed of a signal acquisition and control system 1 and a laser scanner. The signal acquisition and control system 1 mainly includes an industrial control computer, an I / O input and output card and a 5375 optical isolation power amplifier output board. The industrial control computer is placed in a cabinet, and the 5375 optical isolation power amplifier output board is inserted into the PCI card slot in the industrial computer and connected to the I / O input and output card through a cable; the signal acquisition and control system is placed on the left side of two columns 4 and 7. Both columns are 150mm×150mm square steel, as shown in the figure, and each column is fastened to the ground by four M16 bolts. The heights of columns 4 and 7 are l1 and l2 respectively. The range of l1 is 2 meters to 2.5 meters, and the range of l2 is 0.5 meters to 1 meter. Taking the vehicle's forward direction as the front, the front-to-back distance between the center lines of the two columns is m.

[0043] See also Figure 5a The front two-dimensional laser radar is fixed on both sides of the front column 4 with a rocker arm 5, which is hingedly fixed on the front column 4, and the front two-dimensional laser radar 2 is fixed on the rocker arm through the front radar fixing frame 3. The scanning plane of the front two-dimensional laser radar forms an angle of 20 to 30 degrees with the horizontal plane.

[0044] See also Figure 5b The rear two-dimensional laser radar 9 is fixed to the radar bracket on the upper part of the rear column 7 through the rear radar fixing frame 10. The radar bracket is composed of a square steel plate 8 and an L-shaped steel plate 6. The square steel plate 8 and the L-shaped steel plate 6 are fixed to the two parallel surfaces of the column through four M16×180 high-strength bolts. Two M16 bolt holes are reserved on the L-shaped steel plate 6. The rear two-dimensional laser radar 9 is fixed to the rear radar fixing frame 10, and the rear radar fixing frame 10 is fixed to the radar bracket through two M16×60 high-strength bolts. The scanning plane of the rear two-dimensional laser radar 9 is parallel to the horizontal plane.

[0045] See also Figure 1 , 2, a detection method of a vehicle braking performance detection device

[0046] When the vehicle starts to brake, the signal acquisition and control system 1 controls the front and rear two-dimensional laser radars 2 and 9 to start collecting information; the rear two-dimensional laser radar 9 scans the car tire during the vehicle braking process, obtains the effective data of the tire profile curve by using the gradient change law, and then fits the vehicle tire profile curve, fits the curve by using the nonlinear least squares method, and obtains the common tangent line and common tangent point of the fitting curve, iteratively calculates the matching degree of the two segments of data based on the common tangent point, and when the matching degree reaches the corresponding accuracy, the intersection of the symmetry axis of the two segments of the curve and the common tangent line is determined as the feature point; the front two-dimensional laser radar 2 scans the car bumper during the vehicle braking process, obtains the effective data segment by using the characteristics of the sudden change of the boundary point data, and fits the curve by using the nonlinear least squares method, and then obtains the centroid coordinates of the fitting curve, and obtains the braking distance and average braking deceleration of the car by tracking the centroid coordinate information;

[0047] Braking distance S measurement method:

[0048] When the vehicle starts braking, the signal acquisition and control system 1 controls the two-dimensional laser radar to start collecting data. The angle between the front two-dimensional laser radar 2 and the horizontal plane is θ. The point cloud information is obtained by scanning the car bumper. According to the characteristics of the sudden change of the boundary point data, the effective data is obtained. The curve is fitted using the nonlinear least squares method to obtain the centroid coordinates of the curve; suppose the reading of a data point of the two-dimensional laser radar is (ρ, α, θ), ρ is the distance value from the point to the laser emission center point A on the scanning plane, α is the angle value of the scanning laser beam passing through the measured point, and θ is the angle between the scanning plane of the rear two-dimensional radar 9 and the horizontal plane. Then the spatial coordinates of the data point are

[0049]

[0050] Record the starting coordinate of the centroid point in the x-axis direction, recorded as X s When the braking is finished, record the coordinate of the centroid in the x-axis direction, denoted as X e , vehicle braking distance S = X e -X s ;

[0051] Braking stability detection method:

[0052] When the vehicle starts to brake, the signal acquisition and control system 1 controls the rear two-dimensional laser radar 9 to horizontally scan the position of the rear wheels of the vehicle to obtain the point cloud information of the rear tires.

[0053] The measured point in the two-dimensional laser radar scanning plane is saved in polar coordinates and recorded as (ρ, α), where ρ is the distance from the point to the laser emission center B on the scanning plane, and α is the angle of the scanning laser beam passing through the measured point; the acquired point cloud data is converted to the rectangular coordinate system of the starting scanning plane, and the conversion formula is:

[0054]

[0055] Where C is a fixed constant.

[0056] The curve changing rule is analyzed based on the second-order derivative of the curve to extract the smooth changing segment of the tire profile curve and obtain the tire profile curve of the rear tire.

[0057] The nonlinear least square method is used to fit the curves and the common tangent line and common tangent point of the two curves are obtained.

[0058] Taking the common tangent point as the reference, take the same length on both sides to obtain two new data curves and perform matching analysis until the matching accuracy requirement is met; the symmetry axis is obtained about the common tangent line and the common tangent point, and the intersection of the symmetry axis and the common tangent line is the feature point.

[0059] By obtaining the coordinates of the feature point in the v-axis direction when the car starts braking and the coordinates of the feature point on the v-axis after the braking ends, the difference is the horizontal displacement of the vehicle.

[0060] Average braking deceleration MFDD detection:

[0061] The coordinate value X of the vehicle at time point t is obtained by the front two-dimensional laser radar 2 and the signal acquisition and control system 1. t After Δt time, the vehicle X coordinate value X is obtained. t+Δt , calculate the vehicle speed

[0062]

[0063] Calculate the fully developed average deceleration MFDD using the following formula:

[0064]

[0065] Among them, u b is the vehicle speed of 0.8u0 (km / h); u0 is the actual braking speed (km / h); u e The vehicle speed is 0.1u0 (km / h); s b From u0 to u b Distance traveled by the vehicle (m); s e From u0 to u e Distance traveled by the vehicle (m).

Claims

1. A method for detecting the braking performance of a vehicle road test based on a two-dimensional laser radar, wherein the device used in the method comprises a laser scanning device and a signal acquisition and control system, wherein the laser scanning device is composed of two front and rear two-dimensional laser radars of the same model, wherein the front and rear two-dimensional laser radars are respectively installed on the front and rear pillars on the right side of the forward direction of the inspected vehicle, wherein the distance between the front and rear pillars is 5 to 10 m, the height of the front pillar is 2 to 2.5 m, and the height of the rear pillar is 0.5 to 1 m; It is characterized in that The method for detecting the braking performance of a vehicle road test by the detection device comprises the following steps: Step 1: Detect the braking distance and average braking deceleration of the car: When the vehicle starts to brake, the signal acquisition and control system controls the front and rear two-dimensional laser radars to start collecting information; the rear two-dimensional laser radar scans the car tires during the vehicle braking process, obtains the effective data of the tire profile curve by using the gradient change law, and then fits the vehicle tire profile curve, fits the curve by using the nonlinear least squares method, and obtains the common tangent line and common tangent point of the fitting curve, iteratively calculates the matching degree of the two segments of data based on the common tangent point, and when the matching degree reaches the corresponding accuracy, the intersection of the symmetry axis of the two segments of the curve and the common tangent line is determined as the feature point; the front two-dimensional laser radar scans the car bumper during the vehicle braking process, obtains the effective data segment by using the characteristics of the sudden change of the boundary point data, fits the curve by using the nonlinear least squares method, and then obtains the centroid coordinates of the fitting curve, and obtains the braking distance and average braking deceleration of the car by tracking the centroid coordinate information; Step 2: Measurement method of braking distance S: When the vehicle starts braking, the signal acquisition and control system controls the front and rear two-dimensional laser radars to start collecting data. The angle between the front two-dimensional laser radar and the horizontal plane is θ. The point cloud information is obtained by scanning the car bumper. According to the characteristics of the sudden change of boundary point data, the effective data is obtained. The curve is fitted using the nonlinear least squares method to obtain the centroid coordinates of the curve. Suppose the reading of a data point N of the front two-dimensional laser radar is , is the distance from this point to the laser emission center point A on the scanning plane, is the angle of the scanning laser beam passing through the measured point, θ is the angle between the front two-dimensional laser radar scanning plane and the horizontal plane, then the spatial coordinates of the data point are Record the centroid point at The starting coordinate of the direction is recorded as , when braking ends, record the centroid point at Direction coordinates, denoted as , vehicle braking distance ; Step 3: Braking stability detection method: When the vehicle starts to brake, the signal acquisition and control system controls the rear two-dimensional laser radar to horizontally scan the rear wheel position of the vehicle, and extracts the smooth change segment of the tire profile curve based on the second-order derivative analysis of the curve, and obtains the tire profile curve of the rear tire. The curve is fitted using the nonlinear least squares method, and the common tangent and common tangent point of the two curves are obtained; taking the common tangent point as the reference, the same length is taken on both sides to obtain two new data curves and perform matching analysis until the matching accuracy requirement is met. The intersection of the symmetry axis and the common tangent of the two tire profile curves is the feature point; by obtaining the coordinates of the feature point in the v-axis direction when the vehicle starts braking and the coordinates of the feature point on the v-axis after the braking, the difference is the displacement of the vehicle in the horizontal direction; A certain measured point M in the rear two-dimensional laser radar scanning plane is saved in polar coordinates as (ρ, α), where ρ is the distance from the point to the laser emission center B on the scanning plane, and α is the angle of the scanning laser beam passing through the measured point. The acquired point cloud data is converted into the plane rectangular coordinate system, and the conversion formula is: Where C is a fixed constant; Step 4: Average braking deceleration MFDD detection: The coordinate value of the vehicle at time point t is obtained through the front two-dimensional laser radar and signal acquisition and control system. ,go through Time to get the vehicle's X coordinate value at this time , calculate the vehicle speed Calculate the fully developed average deceleration MFDD using the following formula: in, 0.8 Vehicle speed km / h; is the initial braking speed km / h; 0.1 Vehicle speed km / h; for arrive The distance travelled by the vehicle is m; for arrive The distance m traveled by the vehicle.

2. A vehicle road test braking performance detection method according to claim 1, characterized in that: The front two-dimensional laser radar is fixed on the rocker arm through the front radar fixing frame, and the rocker arm is hinged on the upper part of the front pillar; the rear two-dimensional laser radar is fixed on the L-shaped steel plate through the rear radar fixing frame, and the L-shaped steel plate is fixed on the upper part of the rear pillar.

3. A vehicle road test braking performance detection method according to claim 1 or 2, characterized in that: The laser emission points of the front and rear two-dimensional laser radars are A and B respectively. The distance between the laser emission point A of the front two-dimensional laser radar and the ground is h1, h1=l1-0.5 (meters), and the distance between the laser emission point B of the rear two-dimensional laser radar and the ground is h2, h2=l2-0.3 (meters); the scanning plane of the front two-dimensional laser radar forms an angle θ with the xoy plane, θ= 20~30 0 , the rear two-dimensional laser radar scanning plane is parallel to the xoy plane, and the xoy plane is a horizontal plane.

4. A vehicle road test braking performance detection method according to claim 3, characterized in that: The front two-dimensional laser radar establishes a coordinate system with the laser emission point A as the origin, the vehicle travel direction as the x-axis, the laser scanning direction as the y-axis, and the direction perpendicular to the ground as the z-axis; the rear two-dimensional laser radar establishes a coordinate system with the laser emission point B as the origin, the vehicle travel direction as the u-axis, the laser irradiation direction as the v-axis, and the direction perpendicular to the ground as the w-axis.

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