CN109557549A

CN109557549A - A kind of Vehicle length measurement method based on laser radar

Info

Publication number: CN109557549A
Application number: CN201910100441.1A
Authority: CN
Inventors: 王孖豪; 高飞; 刘浩然; 陈丽格; 汪鹏飞; 卢书芳; 张元鸣; 程振波; 肖刚
Original assignee: Zhejiang University of Technology ZJUT
Current assignee: Zhejiang University of Technology ZJUT
Priority date: 2019-01-31
Filing date: 2019-01-31
Publication date: 2019-04-02

Abstract

The invention proposes a vehicle length measurement method based on laser radar. This method does not require the vehicle under inspection to keep a constant speed for calculating the length of the vehicle outline, and there is no deliberate requirement for the driving speed. Environmental adaptability and high reliability. The measurement error of the vehicle length can be greatly reduced, and the number of re-inspections can be reduced, thereby reducing the time required for vehicle inspection, reducing the workload of inspectors, and improving inspection efficiency.

Description

A kind of Vehicle length measurement method based on laser radar

The present invention relates to the automatic detection field of vehicle gabarit, specifically a kind of Vehicle length measurement side based on laser radar Method.

Background technique

System of the most of measuring station using the automatic measurement vehicle gabarit based on light curtain at present, and light curtain method There are its intrinsic defect, such as its stringent Vehicle Speed requirement, only when vehicle is at the uniform velocity kept straight on 3-5 (km/h), This method can be only achieved the measurement precision of national standard.

Currently being related to Vehicle length measurement method has: and patent of invention (application number: 201610595422.7, title: outside vehicle Wide size light curtain measuring device and method), the length of vehicle is measured by linear measure longimetry light curtain receiver；Patent of invention (application Number: 201610248454.X, a kind of title: light veil type vehicle external profile size detecting device), advanced according to collected vehicle Speed, the wheelbase of different moments, the height of car of different moments and different moments vehicle width, calculate obtain vehicle length Degree；Patent of invention (application number: 201310306743.7, a kind of title: contour dimension fast automatic detecting dress of moving vehicle Set) using detection place two sides laser light curtain to the length for carrying out rough estimate vehicle；Zhou little Bo etc. is (outside a kind of novel vehicle Design [J] the instrumental technique and sensor of wide size detecting system, 2014 (4): 102-105) it is measured using laser-correlation light curtain The length of vehicle；(CAN bus based infrared light curtain formula vehicle overall dimension automatic measuring instrument researches and develops [J] automobile to Peng Yuhua etc. Technology, 2018 (3): 60-62) using CAN bus based infrared light curtain to Vehicle length fast, accurately automatic measurement；? Text can etc. (highway transport vehicle, which loads geometric dimension, to transfinite identification [J] Journal of northeast Forestry university, 2009,37 (4): 108- 111) Vehicle length is measured using light curtain and optoelectronic switch；(vehicle overall dimension detection system designs the Shijiazhuang [D] to Li Dongxing Railway university, 2014) projection measurement principle is utilized, three-dimensional source of parallel light is constructed by light curtain sensor, by detecting vehicle pair Collimated light beam blocks to measure the contour dimensions such as the length of vehicle.These methods are primarily present following problem:

1) in reality measurement, often because vehicle has senile abrasion in use, inspector, which is unfamiliar with, to be examined Vehicle driving operation etc. is various objective and artificial origin, is unable to reach above-mentioned driving requirements.Vehicle gabarit length parameter is caused to need Recheck even artificial detection.Not only detection efficiency is reduced, but also wastes the time of car owner and testing staff.

2) place for carrying out the detection of vehicle gabarit is often in outdoor or semi-enclosed environment, and light curtain is by weather Etc. reasons influence, equipment failure rate is higher, and spoilage is also higher.

Summary of the invention

For the deficiency of existing vehicle gabarit length measurement method, the present invention proposes that a kind of vehicle based on laser radar is long Spend measurement method.

The present invention includes the following steps:

A kind of Vehicle length measurement method based on laser radar, which comprises the steps of:

Step 1: obtaining left and right radar points cloud data frame, the note left and right radar point cloud data of t moment is respectively LP_t={ (x_i, y_i) | i=0,1 ..., d-1, RP_t={ (x_i,y_i) | i=0,1 ..., m-1 }, wherein (x_i,y_i) indicate in point cloud data Coordinate points, d indicate the coordinate points number for including in the left radar data frame of t moment, include in the m expression right radar data frame of t moment Coordinate points number；

Step 2: since initial frame, according to judge vehicle it is initial/terminate frame method and analyze left and right radar points cloud number frame by frame According to, find the target frame met the requirements at first, determine the frame be vehicle drive into the moment, be denoted as t_IN；

Step 3: from t_INFrame starts, according to judge vehicle it is initial/terminate frame method and analyze left and right radar points cloud number frame by frame According to, find the target frame met the requirements at first, determine the frame be vehicle be driven out to the moment, be denoted as t_OUT；

Step 4: according to t_OUTThe point cloud data of -1 frame calculates Vehicle length, specifically: by t_OUTCorresponding cloud number of -1 frame According to being denoted as FP_O={ (x_i,y_i) | i=0,1,2..., k-1 }, k t_OUTThe corresponding coordinate points number of -1 frame；Reject FP_OIn meet y_i < h_f1&&y_i> h_f2Coordinate points, wherein h_f1Indicate t_OUTUpper threshold in -1 frame in coordinate points Y direction, h_f1It indicates t_OUTBottom threshold in -1 frame in coordinate points Y direction；Then Vehicle length L is calculated according to formula (1)_Car:

L_Car=L-s (1)

Wherein, the horizontal distance of laser radar sensor and the left and right laser radar sensor plane of scanning motion, s are before L is indicated FP_OThe abscissa minimum value of middle all the points；

A kind of Vehicle length measurement method based on laser radar, it is characterised in that: one of step 2,3 are sentenced Disconnected vehicle is initial/and terminating frame method, detailed process is as follows:

Step 2.1: rejecting LP_tWith RP_tIn meet y_i< h₀Point, wherein h₀Indicate coordinate points Y-axis side in point cloud data frame Upward threshold value；Merge LP after unified coordinate system_tWith RP_tIt is denoted as P_t, i.e. P_t=LP_t∪RP_t；

Step 2.2: object is calculated in detection zone in left and right laser radar scanning plane according to formula (2) Width w_t,

w_t=x_max-x_min (2)

When meeting w_t> w₀, then t is that vehicle drives into or be driven out to the detection zone moment, wherein w₀Indicate object minimum widith threshold Value.

The present invention has the advantages that 1) this method calculates vehicle gabarit length and is not necessarily to protect in inspection vehicle compared with light curtain method It holds and drives at a constant speed, for travel speed also without deliberately requiring.And the measurement accuracy of laser radar is higher than the measurement accuracy of light curtain；2) Environmental suitability and reliability are even more to be much higher than light curtain；3) measurement error of Vehicle length can be greatly reduced, reinspection is reduced Number improves detection efficiency to mitigate testing staff's work load the time required to reducing vehicle detection.With good reality With value and promotion prospect.

Detailed description of the invention

Fig. 1 is the schematic diagram of laser radar apparatus installation site；

Fig. 2 is that vehicle enters vehicle commander measured zone moment t₀When, the schematic diagram in inspection vehicle driving position；

Fig. 3 is that vehicle commander measures finish time t₁When, the schematic diagram in inspection vehicle driving position；

Fig. 4 is the coordinate value of the partial dot from the frame point cloud data that laser radar obtains；

In figure: the left laser radar sensor of 1-, the right laser radar sensor of 2-, laser radar sensor before 3-, 4- detection Laser radar sensor mounting height h before lane length L, 5-, 9- detect lane length L, 10- tested vehicle length L_Car, 14- Lane length L is detected, horizontal distance S, 16- the tested vehicle length of laser radar sensor and tested vehicle leading edge before 15- L_Car。

Specific embodiment

Below with reference to specific example, to illustrate a kind of implementation of the Vehicle length measurement method based on laser radar of the present invention Mode.

A kind of Vehicle length measurement method based on laser radar, specifically comprises the following steps:

Step 1: obtaining corresponding left and right radar points cloud data frame of each moment, remember the left and right radar point cloud data of t moment Respectively LP_t={ (x_i,y_i) | i=0,1 ..., d-1, RP_t={ (x_i,y_i) | i=0,1 ..., m-1 }, wherein (x_i,y_i) table Show the coordinate points in point cloud data, d indicates the coordinate points number for including in the left radar data frame of t moment, and m indicates the right thunder of t moment Up to the coordinate points number for including in data frame；

Step 4: according to t_OUTThe point cloud data of -1 frame calculates Vehicle length；Specific steps are as follows: by t_OUTThe corresponding point of -1 frame Cloud data are denoted as FP_O={ (x_i,y_i) | i=0,1,2 ..., k-1 }, k t_OUTThe corresponding coordinate points number of -1 frame；Reject FP_OIn it is full Sufficient y_i< h_f1&&y_i> h_f2Coordinate points, wherein h_f1Indicate t_OUTUpper threshold in -1 frame in coordinate points Y direction, h_f1Table Show t_OUTBottom threshold in -1 frame in coordinate points Y direction；Then Vehicle length L is calculated according to formula (1)_Car:

L_Car=L-s (1)

Wherein, the horizontal distance of laser radar sensor and the left and right laser radar sensor plane of scanning motion, s are before L is indicated FP_OThe abscissa minimum value of middle all the points；In this example, h_f1=200mm, h_f2=4000mm, L=23670mm, s= 15661mm。

Wherein one of step 2,3 judge vehicle it is initial/terminating frame method, detailed process is as follows:

Step 2.1: rejecting LP_tWith RP_tIn meet y_i< h₀Point, wherein h₀Indicate coordinate points Y-axis side in point cloud data frame Upward threshold value；Merge LP after unified coordinate system_tWith RP_tIt is denoted as P_t, i.e. P_t=LP_t∪RP_t；In this example, h₀=200mm；

Step 2.2: object is calculated in detection zone in left and right laser radar scanning plane according to formula (2) Width w_t, when meeting w_t> w₀, then t is that vehicle drives into or be driven out to the detection zone moment, wherein w₀Indicate object minimum widith threshold Value；In this example, w₀=1000mm

w_t=x_max-x_min (2)

Content described in this specification embodiment is only enumerating to the way of realization of inventive concept, protection of the invention Range should not be construed as being limited to the specific forms stated in the embodiments, and protection scope of the present invention is also and in this field skill Art personnel conceive according to the present invention it is conceivable that equivalent technologies mean.

Claims

1. a vehicle length measurement method based on laser radar, is characterized in that, comprises the steps:

Step 1: Obtain the left and right radar point cloud data frames, and record the left and right radar point cloud data at time t as LP _t ={(x _i ,y _i )|i=0,1,...,d-1 }, RP _t ={(x _i ,y _i )|i=0,1,...,m-1}, where (x _i , y _i ) represents the coordinate point in the point cloud data, and d represents t The number of coordinate points contained in the left radar data frame at time, m represents the number of coordinate points contained in the right radar data frame at time t;

Step 2: Starting from the initial frame, analyze the left and right radar point cloud data frame by frame according to the method of judging the initial/ending frame of the vehicle, find the target frame that meets the requirements first, and determine the frame as the vehicle entry time, denoted as t _IN ;

Step 3: Starting from the t _IN frame, analyze the left and right radar point cloud data frame by frame according to the method of judging the initial/ending frame of the vehicle, find the target frame that meets the requirements first, and determine the frame as the vehicle exit time, denoted as t _OUT ;

Step 4: Calculate the vehicle length according to the point cloud data of the t _OUT -1 frame, specifically: record the point cloud data corresponding to the t _OUT -1 frame as FP _O ={(x _i ,y _i )|i=0,1 ,2...,k-1}, k is the number of coordinate points corresponding to t _OUT -1 frame; remove the coordinate points that satisfy y _i <h _f1 && y _i >h _f2 in FP _O , where h _f1 represents t _OUT The upper limit of the threshold value in the Y-axis direction of the coordinate point in the -1 frame, h _f1 represents the lower limit of the threshold value in the Y-axis direction of the coordinate point in the t _OUT -1 frame; then calculate the vehicle length L _Car according to formula (1):

L _Car = Ls (1)

Among them, L represents the horizontal distance between the front lidar sensor and the scanning plane of the left and right lidar sensors, and s is the minimum _abscissa of all points in FPO.

2. a kind of vehicle length measurement method based on lidar according to claim 1, is characterized in that, the concrete process of a kind of judging vehicle initial/end frame method in described steps 2,3 is as follows:

Step 2.1: Eliminate the points in LP _t and RP _t that satisfy y _i <h ₀ , where h ₀ represents the threshold in the Y-axis direction of the coordinate point in the point cloud data frame; after unifying the coordinate system, LP _t and RP _t are combined and recorded as P _t , that is, P _t =LP _t ∪RP _t ;

Step 2.2: Calculate the width w _t of the object in the detection area on the left and right lidar scanning planes according to formula (2),

w _t = x _max -x _min (2)

When w _t >w ₀ is satisfied, then t is the time when the vehicle enters or leaves the detection area, where w ₀ represents the minimum object width threshold.