CN110091800B

CN110091800B - Image display and danger early warning method and device for vehicle electronic rearview mirror

Info

Publication number: CN110091800B
Application number: CN201910252246.0A
Authority: CN
Inventors: 肖文平; 陈祥栋; 张航
Original assignee: Shanghai Hinge Electronic Technologies Co Ltd
Current assignee: Shanghai Hinge Electronic Technologies Co Ltd
Priority date: 2019-03-29
Filing date: 2019-03-29
Publication date: 2021-08-20
Anticipated expiration: 2039-03-29
Also published as: CN110091800A

Abstract

The invention discloses an image display and danger early warning method for an electronic rearview mirror of a vehicle, which at least comprises the following steps: acquiring video images of a vehicle in a plurality of preset acquisition directions; displaying a plurality of video images to a driver; processing and displaying the corresponding view images according to the vehicle signals and a preset optimization mode; video images in a plurality of preset acquisition directions are acquired and then transmitted through a vehicle-mounted Ethernet network; the preset optimization mode at least comprises one or more of a forward driving mode, a left turning mode, a right turning mode and a reversing mode; the electronic image display method and the danger display method provided by the invention can provide clear image display pictures for a driver and inform whether a target obstacle appearing on the pictures is in a safe distance range or not, thereby further ensuring the driving safety.

Description

Image display and danger early warning method and device for vehicle electronic rearview mirror

Technical Field

The invention relates to the field of automotive electronics, in particular to an image display and danger early warning method and device for an electronic rearview mirror of a vehicle.

Background

At present, the rearview mirrors installed on the outer sides of automobiles are all optical rearview mirrors, and due to the reason that the mirror surface area and the adjustment angle are limited, the visual dead angles of drivers can be formed in certain areas backwards from the positions of the drivers on the left side and the right side of the automobiles.

Meanwhile, due to the fact that the left and right A columns of the vehicle shield the visual angle of a driver, in the left and right steering processes of the vehicle, the visual dead angle of the driver can be formed in a certain area where the position of the driver moves forward on the left and right sides of the vehicle.

Due to the existence of dead angle blind areas, certain potential safety hazards are brought to driving of the automobile. Meanwhile, the traditional optical exterior rearview mirror has the defects of complex structure, large volume, large wind resistance, large wind noise and the like, and the driving economy and comfort are influenced.

In addition, more and more automobiles are currently equipped with a driving assistance device, a reverse sensor. The initial car backing collision avoidance instrument can detect obstacles in a certain distance range behind a car and give an alarm, and then the alarm is developed into a segmented alarm according to the distance. The reversing radar in the first two stages has a simple function, and the safety is not enough, so that the novel reversing radar system is an intelligent distance measurement sensing system with a single chip microcomputer as a core. When an automobile is backed, a method needing non-contact distance measurement, namely laser infrared rays and ultrasonic waves, is high in distance measurement precision and simple to operate, but is greatly influenced by the environment, the system is not easy to maintain in detection, the price is high, the infrared distance measurement is easily influenced by the ambient illuminance and the light color, and the measurement precision is low. Compared with the prior art, the ultrasonic wave is mechanical wave, has the characteristics of no light influence, no electromagnetic interference, low cost and the like, can measure the material level at fixed points and continuously, has better adaptability in severe environments such as dust, smoke, corrosion and the like, and is widely applied to aspects such as obstacle avoidance of the reversing radar robot controlled by the material level measuring manipulator and other industrial fields. Therefore, in recent years, much research and study has been conducted on ultrasonic ranging. However, the existing ultrasonic ranging sensors are generally small in ranging range, poor in linearity and repeatability, inaccurate in early warning range and the like, and a high-precision ultrasonic ranging-based automobile reversing early warning obstacle avoidance system needs to be invented, is a safety auxiliary device for automobile parking or reversing, can inform a driver of the situation of obstacles around the automobile through sound or more visual display, solves the trouble caused by the driver in front-back and left-right visiting when parking, reversing and starting the automobile, can help the driver to eliminate the defects of dead angle and blurred vision, and improves the driving safety.

Disclosure of Invention

In order to solve the problems, the invention provides an image display and danger early warning method and device of a vehicle electronic rearview mirror, which can avoid the formation of a view blind area, optimize a display mode based on vehicle signals, enable the image display effect of the surrounding environment of a vehicle and the reversing view environment to be better, detect the distance between the vehicle and an obstacle, automatically brake and control a dangerous case when the situation is emergent.

An image display and danger early warning method for a vehicle electronic rearview mirror at least comprises an electronic rearview mirror image display method, and specifically comprises the following steps:

acquiring video images of a vehicle in a plurality of preset acquisition directions;

displaying a plurality of video images to a driver;

processing and displaying the corresponding view images according to the vehicle signals and a preset optimization mode;

video images in a plurality of preset acquisition directions are acquired and then transmitted through a vehicle-mounted Ethernet network;

the preset optimization mode at least comprises one or more of a forward driving mode, a left turning mode, a right turning mode and a reversing mode;

in the forward driving mode, the images displayed on the display screen are as follows: displaying the video image collected at the front left at a normal visual angle, displaying the video image collected at the rear left at a wide-angle visual angle, displaying the video image collected at the front right at a normal visual angle, and displaying the video image collected at the rear right at a wide-angle visual angle;

in the left turn mode, the images displayed by the display screen are: displaying the video images collected at the left front and the left rear at a wide angle of view, displaying the video image at the right front at a normal angle of view, and displaying the video image at the right rear at a wide angle of view;

in the right turn mode, the images displayed by the display screen are: displaying the video images collected at the front left side at a normal visual angle, displaying the video images collected at the rear left side at a wide-angle visual angle, and displaying the video images collected at the front right side and the rear right side at the wide-angle visual angle;

in the reverse mode, the images displayed by the display screen are as follows: and displaying the video images collected at the left front and the left rear at a wide angle of view, and displaying the video images collected at the right front and the right rear at a wide angle of view.

In the preset optimization mode, a normal or optimized video image processing mode is set and stored correspondingly for different vehicle signals;

preferably, the vehicle signal comprises any one of: driving operation signals, sensor signals, vehicle state signals.

Preferably, the driving operation signal includes: and (3) forward driving, left turning, right turning and backing, and correspondingly setting and storing normal or optimized video image processing modes for driving operation signals in different preset acquisition directions.

Preferably, the plurality of predetermined acquisition directions comprises: the left front direction, the left rear direction, the right front direction and the right rear direction of the vehicle.

Preferably, the method of displaying the plurality of video images to the driver includes: be equipped with left post display screen on the inside left A post of vehicle, be equipped with right post display screen on the right A post, the video image on left front and left rear direction is shown through left post display screen, and the video image on right front and right rear direction is shown through right post display screen.

Preferably, the normal display mode of the video image includes: the visual angle is within 60 degrees, and the wide-angle optimization mode of the video image comprises the following steps: the angle of visibility is greater than 120.

Preferably, the image processing unit comprises a main controller, a communication interface in communication connection with the camera, an in-vehicle data interface in communication connection with other in-vehicle external devices, and an image output unit in communication connection with the display screen, wherein the main controller is respectively connected with the image output unit, the in-vehicle data interface, and the communication interface.

Preferably, the image display method comprises the following specific steps:

step S1, the data interface in the vehicle receives the vehicle gear signal and enters step S2;

step S2, transmitting the vehicle gear signal to the main controller, and entering step S3;

step S3, judging whether the vehicle is under the reverse gear position, if not, entering step S4, if yes, entering step S5;

step S4, entering the state, judging that the driving operation signal of the vehicle is in a forward mode, displaying the video image as a normal left front and a wide left rear angle and a normal right front and a wide right rear angle by the main controller, and entering the step S6;

step S5, entering the state, judging that the driving operation signal of the vehicle is in a reverse mode, displaying the video image as a left front wide angle, a left rear wide angle, a right front wide angle and a right rear wide angle by the main controller 101, and entering the step S6;

step S6, judging whether the data interface in the vehicle receives the steering signal, if so, indicating that the vehicle is steered, and entering step S7, if not, indicating that the vehicle is steered, and entering step S11;

step S7, transmitting the steering signal to the main controller, and entering step S8;

step S8, judging the concrete type of the steering signal, entering step S10 when judging the steering signal is a left steering signal, and entering step S9 when judging the steering signal is a right steering signal;

step S9, the main controller adjusts the video image to be normal left-front, wide left-back, wide right-front and wide right-back, and then the process goes to step S11;

step S10, the main controller adjusts the video image to a wide angle at the front left, a wide angle at the back left, a normal front right and a wide angle at the back right, and the process goes to step S11;

step S11, the main controller sends the video image to the image output unit, and proceeds to step S12;

step S12, the image output unit outputs the image to the left display screen and the right display screen, and the step S13 is entered;

and step S13, displaying corresponding images on the left display screen and the right display screen.

The invention also provides a danger early warning method, which specifically comprises the following steps:

step B1: acquiring a target distance between the vehicle and the obstacle through ultrasonic ranging;

step B2: judging whether the target distance is smaller than M1, if so, executing a step B3, otherwise, continuously judging whether the new target distance is smaller than M1;

step B3: starting voice early warning;

step B4: judging whether the target distance is smaller than M2, if so, executing a step B5, otherwise, continuously judging whether the new target distance is smaller than M2;

step B5: starting a buzzing early warning;

step B6: and (5) emergency automatic stop.

Preferably, in step B1, the ultrasonic ranging specifically includes:

step B11: the micro-processing controller generates a pulse signal with the frequency of more than 20KHz, the pulse signal is amplified after passing through the transmitting circuit, and the amplified pulse signal enters the transmitting sensor and drives the transmitting sensor to emit a series of ultrasonic waves;

step B12: the ultrasonic waves are transmitted in a straight line in an air medium and are reflected by an obstacle after encountering the obstacle;

step B13: the reflected ultrasonic echo can be received by the receiving sensor, signal processing is carried out on the reflected ultrasonic echo through the receiving circuit, signals of the processor are transmitted to the micro-processing controller, and echo signal denoising processing can be carried out through the micro-processing controller or the receiving circuit.

Step R14: the microprocessor acquires the target distance according to the time difference between the sending and receiving of the ultrasonic waves and the transmission rate of the ultrasonic waves.

Preferably, in step B13, the denoising processing of the ultrasonic echo signal includes the following steps:

step B131:

establishing an expression (1):

x(i)＝s(i)+n(i) (1)

formula (1), wherein i is 0, 1., N-1, x (i) is a function of noisy signals, s (i) is a function of useful signals, and N (i) is a function of noise;

step B132: selecting a wavelet basis function with vanishing moment N, wherein the wavelet basis function comprises one of DbN function, SymN function and CoifN function, and N is the vanishing moment of the wavelet basis function;

step B133: selecting the number J of decomposition layers, and performing orthogonal wavelet transform on the signal by using the formula (2) to obtain the scale coefficient c of each layer_j，kSum wavelet coefficient d_j，k，

In the formula: k is 0, 1, R-1, J is 0, 1, J is the number of decomposition layers, R is the number of signal sampling points, and h and g are each an orthogonal filter bank;

step B134: selecting threshold function, and applying wavelet coefficient d to each layer_j，kThresholding is carried out, scale coefficient c_j，kKeeping the threshold value constant, selecting one of the formula (3) or the formula (4) by the threshold value function,

in the formula (3), d_j，kThe coefficients of the original wavelet are then compared,

is a wavelet coefficient processed by a threshold function, and Thr is a threshold;

in the formula (4), d_j，kThe coefficients of the original wavelet are then compared,

is a wavelet coefficient processed by a threshold function, Thr is a threshold value, and sgn is a step function; the Thr threshold is calculated by adopting a formula (5):

in the formula (5), j is the current decomposition layer number, Nj is the length of the wavelet coefficient of the current decomposition layer number, and sigma is the standard variance of the signal, which needs to be estimated from the noisy signal;

step B135: reconstructing the signal, selecting a new wavelet coefficient to reconstruct the signal according to the formula (7), wherein the reconstructed signal is the de-noised signal,

preferably, in the step B14, the calculation of the transmission rate of the ultrasonic wave is performed according to one of formula (8) and formula (8):

in formula (8), wherein: c is the transmission rate of ultrasonic waves, and gamma is the ratio of air to heat capacity (the ratio of constant pressure heat capacity to constant volume heat capacity); r ideal gas constant in air; mu is air molar mass; t is the absolute temperature of the gas, and T is the temperature in centigrade;

in formula (9): c is the transmission rate of the ultrasonic wave, T is T +273.15, T is the absolute temperature of air, and T is the temperature in centigrade; gamma is the specific heat capacity of air; p₀The pressure of the humid air;

relative humidity of the humid air, Psb is saturated water vapor partial pressure;

when the allowable ranging error does not exceed 4%, the transmission rate of the ultrasonic wave only needs to be calculated according to the formula (8), otherwise, the transmission rate of the ultrasonic wave is calculated by using the formula (9).

Preferably, in the step B2, the safe distance M1 has a value range of 0.5 to 1M, and the dangerous distance M2 has a value range of 0.2 to 0.3M.

Preferably, the SNR is less than or equal to 20dB, J is 4 or SNR >20dB, and J is 3, wherein SNR (signal to Noise ratio) is the SNR.

Preferably, in step B134, the threshold function is:

d_j,kthe coefficients of the original wavelet are then compared,

is passing a threshold functionAnd (4) the wavelet coefficient after the number processing is that a is more than or equal to 0 and Thr is a threshold value.

In addition, the invention also provides an image display and danger early warning device of the vehicle electronic rearview mirror, which is characterized by comprising the image display device and the danger early warning device of the vehicle electronic rearview mirror,

wherein the image display apparatus includes:

the system comprises a plurality of cameras, a plurality of sensors and a control unit, wherein the cameras are used for acquiring video images of a vehicle in a plurality of preset acquisition directions;

the display screen displays a plurality of video images facing a driver;

and the image processing unit is used for processing and displaying the corresponding view field image according to the vehicle signal and a preset optimization mode.

preferably, in the forward running mode, the image displayed on the display screen is: displaying the video image collected at the front left at a normal visual angle, displaying the video image collected at the rear left at a wide-angle visual angle, displaying the video image collected at the front right at a normal visual angle, and displaying the video image collected at the rear right at a wide-angle visual angle;

Preferably, the method of displaying the plurality of video images to the driver includes:

a left column display screen is arranged on a left column A in the vehicle, a right column display screen is arranged on a right column A, video images in the left front and left rear directions are displayed through the left column display screen, and video images in the right front and right rear directions are displayed through the right column display screen;

Preferably, the image processing unit includes a main controller, a communication interface in communication with the camera, an in-vehicle data interface in communication with other in-vehicle external devices, and an image output unit in communication with the display screen, wherein the main controller is respectively connected to the image output unit, the in-vehicle data interface, and the communication interface.

The present invention provides a hazard warning device comprising:

a microprocessor controller, a transmitting circuit, a receiving circuit, a transmitting sensor, a receiving sensor and a voice reminding module, wherein the microprocessor controller is respectively connected with the transmitting circuit, the receiving circuit and the voice reminding module,

the transmitting circuit is connected with the transmitting sensor, and the receiving circuit is connected with the receiving sensor.

In addition, the micro-processing controller is also connected with the main controller in the image processing unit.

The danger alarm equipment also comprises a temperature sensor and a humidity sensor which are used for detecting the temperature and the humidity outside the vehicle, and the temperature sensor and the humidity sensor are respectively connected with the micro-processing controller.

The danger alarm device is used for ranging the distance between a vehicle and an obstacle, when the distance between a target obstacle and the vehicle is within a preset range, the danger alarm system starts the voice reminding module to give an alarm or carries out microprocessing control to generate a signal which needs to be automatically braked and transmits the signal to the central control of the vehicle, so that the safe braking of the vehicle is realized, and accidents are prevented;

preferably, the target distance between the vehicle and the obstacle is displayed on an electronic rearview mirror.

Principle of ultrasonic ranging:

the ultrasonic transmitter transmits ultrasonic waves to a certain direction, timing is started at the same time of transmitting time, the ultrasonic waves are transmitted in the air and return immediately when encountering an obstacle in the process, and the ultrasonic receiver stops timing immediately when receiving reflected waves. The propagation speed of the ultrasonic wave in the air is 340m/s, and the distance(s) of the transmitting point from the obstacle can be calculated according to the time t recorded by the timer, namely: and s is 340 t/2.

The principle of ultrasonic ranging is that the propagation speed of ultrasonic waves in the air is known, the time of the sound waves reflected back when encountering an obstacle after being transmitted is measured, and the actual distance from a transmitting point to the obstacle is calculated according to the time difference between transmitting and receiving.

The formula for ranging is expressed as: m ═ C × t formula (6)

M in formula (6) is the measured distance length; c is the propagation speed of the ultrasonic wave in the air; t is the time difference of the measured range propagation (t is half the value of the transmit-to-receive time).

Compared with the prior art, the technical scheme of the invention can obtain the following beneficial effects:

1) the invention provides a method and a device for displaying images and warning danger of an electronic rearview mirror of a vehicle, wherein the method and the device for displaying the electronic images of the vehicle process the corresponding visual field images according to a preset optimization mode through video images in a plurality of preset acquisition directions around the acquired vehicle according to vehicle signals, such as sensor signals and vehicle state signals, so that the left and right blind areas seen by a driver in the driving process are reduced, and the images around the vehicle body with wider visual angle range are displayed through a display screen in the vehicle based on driving operation signals through a camera and a related image control unit, thereby achieving the purpose of optimizing the display and improving the safety and comfort of the user in driving the vehicle.

2) The influence of the ambient temperature and the humidity on the ultrasonic transmission rate is considered in the ultrasonic ranging, and the ranging precision between the vehicle and the current barrier is improved, so that the safety early warning or the automatic braking distance can be provided.

3) In addition, when the ultrasonic wave is adopted for ranging, because signal interferences such as thermal noise, bottom clutter and the like exist, the ranging precision is greatly reduced, the general wavelet threshold value method improves parameters in the method, constructs a threshold value function, considers the influence of the environmental temperature and humidity on the ultrasonic wave transmission rate for the ultrasonic ranging, improves the ranging precision between the vehicle and the current barrier, and can provide prepared safety early warning or automatic braking distance.

The camera is used for shooting the image of the surrounding environment of the vehicle and displaying the image in the electronic rearview mirror, so that a clearer image can be provided for a driver, but the driver does not know how far the object displayed by the image of the electronic rearview mirror is away from the vehicle and whether the object is in a safe distance. The electronic image display method and the danger display method provided by the invention can provide clear image display pictures for a driver and inform whether a target obstacle appearing on the pictures is in a safe distance range or not, thereby further ensuring the driving safety.

Drawings

FIG. 1 is a schematic view of an image display and danger warning device for an electronic rearview mirror of a vehicle according to an embodiment of the present invention;

FIG. 2 is a flowchart of an image processing method for displaying an electronic rearview mirror of a vehicle according to an embodiment of the present invention;

FIG. 3 is a schematic table diagram of a predetermined optimization mode of the vehicular electronic rearview mirror in the embodiment of the invention;

FIG. 4 is a flow chart of the early warning process of the danger early warning device in the embodiment of the present invention; and

fig. 5 is a schematic view of ultrasonic ranging of the hazard warning apparatus in the embodiment of the present invention.

Detailed Description

The above and other objects, features and advantages of the present invention will become more apparent by describing in detail preferred embodiments thereof with reference to the accompanying drawings in which:

fig. 1 is a schematic structural diagram of an image display device and a danger warning device for a vehicle electronic rearview mirror in an implementation of the present invention.

As shown in fig. 1, the vehicular electronic image display apparatus includes an image processing unit 1, a wide-angle camera 2, an in-vehicle ethernet 3, and an image display screen 4. The image processing unit 1 includes a main controller 101, a communication interface 102, an in-vehicle high-speed data interface 103, and an image output unit 104. The vehicle electronic image display device further includes an omitted memory connected to the main controller 101 for storing a predetermined optimization pattern table.

The communication interface 102 is in communication connection with the wide-angle camera 2, the in-vehicle high-speed data interface 102 is used for being in communication connection with other in-vehicle external equipment, the image output unit 104 is in communication connection with the image display screen 4, and the main controller 101 is respectively connected with the communication interface 102, the in-vehicle high-speed data interface 103 and the image output unit 104.

The wide-angle camera 2 comprises four cameras installed on a vehicle body, and adopts a wide-angle camera, and the invention can also adopt corresponding cameras based on other image optimization modes, namely a first wide-angle camera, a second wide-angle camera, a third wide-angle camera and a fourth wide-angle camera, and respectively and correspondingly collects image data of the left front, the left rear, the right front and the right rear of the vehicle. The collected image data may be transmitted to the communication interface 102 through the vehicle ethernet 3, and then the communication interface 102 collectively transmits the received four paths of ethernet data to the main controller 101. The in-vehicle high-speed data interface 103 transmits the received in-vehicle data to the main controller 101, the main controller 101 processes four paths of image data of the wide-angle camera 2 after judging the data, and transmits the processed image data to the image output unit 104, and the image output unit 104 transmits the processed image information to two display screens of the image display screens 4 respectively.

The display screen contains left display screen and right display screen in this embodiment, and the left place ahead, the image data display of left rear are on the left display screen in above-mentioned image display screen 4, and left display screen installs on the inside left A post of vehicle. The right front and right rear image data is displayed on a right display screen among the above-mentioned image display screens 4, the right display screen being mounted on a right a pillar inside the vehicle.

The danger early warning apparatus 200 includes: the system comprises a microprocessor controller 201, a transmitting circuit 202, a receiving circuit 203, a transmitting sensor 204, a receiving sensor 205 and a voice reminding module 206, wherein the microprocessor controller 201 is respectively connected with the transmitting circuit 202, the receiving circuit 203 and the voice reminding module 206.

The transmitting circuit 202 is connected to the transmitting sensor 204, and the receiving circuit 203 is connected to the receiving sensor 205.

In addition, the micro-process controller 201 is also connected to the main controller 101 in the image processing unit 1.

The hazard warning apparatus 200 further includes a temperature sensor and a humidity sensor for detecting the temperature and humidity outside the vehicle, and the temperature sensor and the humidity sensor are respectively connected to a microprocessor controller (not shown in the figure).

The microprocessor control 201 of the hazard warning device 200 is also connected to a central processor (not shown) of the vehicle.

Fig. 2 is an image processing flow of the vehicle electronic image display method in the embodiment of the invention. By means of fig. 2, a procedure for a method for electronic image display of a vehicle under different steering signals when the vehicle is in different driving modes.

FIG. 3 is a schematic table diagram of a predetermined optimization mode for optimizing a display in an embodiment of the present invention. The memory is used for storing a predetermined optimization mode table in fig. 3, for example, and the image processing unit 1 processes and displays the corresponding sight field image according to a predetermined optimization mode according to a driving operation signal of the vehicle. As can be seen from fig. 3, in the predetermined optimization mode table, normal or optimized video image processing modes are stored for the driving operation signals under different predetermined acquisition directions.

The process of FIG. 2 is described below in conjunction with the predetermined optimization pattern table of FIG. 3:

step S1, the vehicle interior high speed data interface 103 receives the vehicle gear signal and enters step S2;

step S2, transmitting the vehicle gear signal to the main controller 101, step S3;

in step S3, determine is the vehicle in reverse gear? If no, the process proceeds to step S4, and if yes, the process proceeds to step S5;

step S4, entering the state, judging that the driving operation signal of the vehicle is in the forward mode, displaying the video image by the main controller 101 as a normal left front and a wide left back angle, and a normal right front and a wide right back angle, entering the step S6;

step S6, judging whether the high speed data interface in the vehicle receives the steering signal, if yes, indicating that the vehicle is steered, entering step S7, if no, indicating that the vehicle is steered, entering step S11;

In this embodiment, in the reverse mode, the four directions of the left front, the left rear, the right front and the right rear are all optimized in a wide angle mode. Specifically, for example, the image display at the time of reverse left turn is the same as the left turn mode, and the image display at the time of reverse right turn is the same as the right turn mode.

The processing flow of the above steps S1 to S13 is described below with reference to the respective modules of the image device of the vehicle electronic rearview mirror of fig. 1:

when the vehicle travels forward normally, the main controller 101 processes the received image information and then transmits the processed image information to the image output unit 104. The image output unit 104 transmits the image data of the normal viewing angle at the front left and the wide-angle image data at the rear left to the left display screen of the image display screens 4 for display; the image output unit 104 transmits the right front normal view angle image data and the right rear wide angle image data to the right one of the image display panels 4 for display.

When the in-vehicle high-speed data interface 103 receives a steering signal sent by a vehicle, the steering signal is sent to the main controller 101, and the main controller 101 performs corresponding processing on the received image signal after judging the steering signal. The main controller 101 transmits the processed image signal to the image output unit 104. The vehicle steering signal includes a left steering signal and a right steering signal. In the left turn state, the image output unit 104 transmits the left front wide-angle image and the left rear wide-angle image to the left display screen of the image display screen 4 for display. Transmitting the image data of the normal visual angle at the right back and the wide-angle image data at the right back to a right display screen of the image display screen 4 for display; in the right-turn state, the image output unit 104 transmits the image data of the normal viewing angle at the front left and the image data of the wide viewing angle at the rear left to the left display screen of the image display screen 4 for display. And sending the right front wide-angle image and the right rear wide-angle image to a right display screen of the image display screen 4 for display.

When the in-vehicle high-speed data interface 103 receives a reverse gear signal sent by a vehicle, the reverse gear signal is sent to the main controller 101, and the main controller 101 performs corresponding processing on the received image signal after judging the reverse gear signal. The main controller 101 transmits the processed image signal to the image output unit 104. The image output unit 104 transmits the left front wide-angle image and the left rear wide-angle image to the left display screen of the image display screen 4 for display. And sending the right front wide-angle image and the right rear wide-angle image to a right display screen of the image display screen 4 for display.

The vehicle electronic image display method and the vehicle electronic image display device are specific embodiments of the invention. Of course, the present invention is not limited to the above examples, and various changes may be made in the specific interface form, the detailed part of image processing, and the like. For example, in the above system, the left display screen is disposed on the left a-pillar in the vehicle, and the right display screen is disposed on the right a-pillar in the vehicle. However, it is also possible that the left display screen is arranged on the left door, the center pillar, etc., and the right display screen is arranged on the right door, the center pillar, etc. The left front and left rear images of the vehicle are displayed on the left display screen, and the right front and right rear images of the vehicle are displayed on the right display screen.

In the above embodiment, four wide-angle camera image acquisition devices are arranged on the left and right outside rearview mirrors of the vehicle body, video images are transmitted to the image processing unit through the vehicle-mounted ethernet transmission technology after the images at corresponding positions are acquired, and the image processing unit outputs display pictures to the two-sided display screens mounted on the left and right a-pillars in the vehicle after the images are processed.

Wide-angle cameras typically have viewing angles greater than 120 °, and some even greater than 180 °, as used herein, the viewing angle of a wide-angle camera is greater than 180 °, which allows a greater field of view than a normal viewing angle camera with a viewing angle within 60 °. In the above embodiment, on the basis of fully adopting wide-angle optimization during reversing, the enlarged optimization degree can be adopted to display the corresponding direction during reversing left-hand turning or reversing right-hand turning, and the enlarged optimization degree can be realized by adopting different wide-angle angles, for example, the initial optimization angle is 120 degrees, and the further optimization angle is increased to 160 degrees.

The invention relates to an electronic rearview mirror system for an automobile, which is a rearview system consisting of four cameras and two display screens. Two cameras are respectively arranged on the left side and the right side of the vehicle and respectively face to the front and the rear.

In addition, the electronic image display method for vehicles according to the present invention is not limited to the left-turn and right-turn signals of vehicles, but also includes various sensor signals of vehicles, including rainfall sensor, light sensor, etc., or vehicle state related signals such as low beam and high beam signals of vehicles.

In this embodiment, the specific process of the method and the device for warning and early warning of danger is as follows, and this embodiment will be described in detail with reference to fig. 1, 4, and 5.

Firstly, the micro-processing controller 201 generates a pulse signal and starts timing by the timer 207, and the generated pulse signal is amplified after passing through the transmitting circuit 202, so that the amplitude of the pulse signal is increased. The transmission circuit 202 is a power amplification circuit mainly composed of power amplification devices. The amplified ultrasonic pulse signal drives the transmitting transducer 204 to emit a series of ultrasonic waves, which are propagated linearly in the air medium and, after encountering an obstacle, i.e. the object 300, the reflected echo is reflected by the obstacle and received by the ultrasonic receiving sensor 205, and the back receiving sensor 205 transmits the echo signal to the receiving circuit 203 to remove part of the clutter and transmits the echo signal to the micro-processing controller 201 for signal processing, at this time, if the receiving sensor 205 sends the time of detecting the signal to the microprocessor controller 201, the microprocessor controller 201 starts the timer 207 immediately after receiving the signal to send a signal for stopping timing, the timer 207 will stop timing immediately, the processing process comprises the steps of denoising of echo signals and calculating of target distance, and when the target distance reaches a preset range, an early warning or automatic braking function is started.

In the system, a voice chip, a driving circuit and a loudspeaker are adopted to realize a voice reminding function (not shown in the figure). When the distance between a vehicle rear obstacle and a vehicle is within a dangerous distance range, a rearview mirror system is required to carry out voice reminding on a driver, if the distance meets a voice reminding condition, a voice reminding signal is automatically generated, a serial interface connected with a voice chip through a microprocessor controller sends a voice reminding alarm instruction, and a loudspeaker is driven to carry out voice reminding alarm through a power amplification circuit. If the voice reminding condition is not met, sampling is continued, and judgment is carried out.

The target distance adopts a wavelet threshold change method to remove noise interference, high-quality echo signals are obtained, and the influence of temperature and humidity on the transmission rate of the ultrasonic waves is considered. The removal of echo noise may be performed in the transmit circuitry 202 or in the microprocessor control 201 integrated with DSP processing.

Specifically, in this embodiment, array-type ultrasonic transmitters and receivers are adopted, the array-type ultrasonic transmitters and receivers are respectively installed in the front and the back of the vehicle, each array-type ultrasonic transmitter and receiver is 3, the three transmitters correspond to the three receivers, the included angle between the three transmitters is 60 degrees, and the included angle between the three receivers is also 60 degrees.

Referring to fig. 4, the danger warning and early warning method comprises the following steps:

the target distance is a target distance between the vehicle and the obstacle, and the calculation takes into account the influence of temperature, humidity, and noise.

Step B2: the micro-processing controller judges whether the target distance is smaller than a safe distance M1, if so, the step B3 is executed, otherwise, the new target distance is continuously judged whether to be smaller than M1;

specifically, the safe distance M1 and the dangerous distance M2 defined in the present embodiment generally represent that the vehicle is safe, and the dangerous distance represents that the vehicle is in a dangerous state at this time, and the driver needs to perform manual intervention to brake, etc. However, the factors affecting the safe distance M1 and the dangerous distance M2 are many, and they are performed according to the vehicle speed and the reaction speed of the person. This may be defined on its own, depending on the situation, the safety distance defined in this embodiment being used only in applications where the vehicle speed is slow, such as reversing. Because the vehicle in-process that gos forward, driver's sight is better, can judge the distance adoption measure of barrier according to eyes, and ultrasonic ranging plays driver's warning effect at this moment at the display screen in the electron rear-view mirror. However, the backing conditions are different, the driver of the vehicle depends on the electronic rearview mirror, and the speed in the backing process is slow generally.

Here, M1 is 0.5 to 1M, and M2 is 0.1 to 0.2M. In the examples, M1 is 0.5M, and M2 is 0.2M is most preferable.

Step B3: when the target distance is less than the safe distance M1 which is equal to 0.5, the microprocessor controller controls the voice reminding module to perform voice early warning;

step B4: judging whether the target distance is smaller than a dangerous distance M2, if so, executing a step B5, otherwise, continuously judging whether the new target distance is smaller than M2;

here, M2 is 0.1 to 0.2M. In the examples, M2 is preferably 0.2M.

Step B5: when the target distance is less than M1-0.2, starting a buzzing early warning;

step B6: the microprocessor controller transmits an emergency brake signal to the vehicle central control processor, and the central control processor receives the emergency brake signal to realize automatic emergency automatic stop.

The method for denoising the ultrasonic echo signal comprises the following steps:

step B131:

establishing an expression (1):

x(i)＝s(i)+n(i) (1)

step B132: selecting a wavelet basis function with vanishing moment N. In the present invention, one of, but not limited to, DbN function, SymN function, and CoifN function is selected, where N is the vanishing moment of the wavelet basis function.

DbN, SymN and CoifN belong to orthogonal wavelet bases, and Daubechies wavelets are abbreviated as db wavelets. dbN, N represents the order of db wavelet, and N is 2-10. When N is 1, db1 is a Haar wavelet. Thus, the aforementioned Haar wavelets are due to the class of "orthogonal wavelets". Symmetric wavelets are abbreviated as SymN, N2, 3, Λ, 8, which is an improvement of db wavelets. coifN is a tightly supported orthogonal, biorthogonal wavelet with a support range of 6N-1, which is also nearly symmetrical. Therefore, a suitable wavelet basis is selected according to the waveform and the measured environment, and in the embodiment, SymN is selected as the wavelet basis.

theoretically, the more the maximum hierarchical layers of wavelet decomposition, the more obvious the unmatched characteristics of noise and signals are, and the easier the separation of signals and noise is, but the more the number of decomposition layers is, the greater the reconstruction distortion is. SNR is less than or equal to 20dB, J is 2-4 or SNR is more than 20dB, and J is 3. When a Sym wavelet base is adopted, J is 2.

Step B134: selecting threshold function, and applying wavelet coefficient d to each layer_j,kThresholding is carried out, scale coefficient c_j,kThe threshold function is selected from one of the equations (3) or (4) while remaining unchanged.

In the formula (3), d_j,kThe coefficients of the original wavelet are then compared,

in the formula (4), d_j,kThe coefficients of the original wavelet are then compared,

is a wavelet coefficient processed by a threshold function, Thr is a threshold value, and sgn is a step function;

since the scale threshold is generally a low-frequency useful signal, and the wavelet system is generally a high-frequency noise signal, the wavelet coefficients d of each layer are quantized by selecting a reasonable threshold function and threshold_j,kThe value of (c).

Thr is the threshold value, which, in the prior art,

r is the number of sampling points,

where σ is the standard deviation of the noise. σ can be estimated using the wavelet coefficient d1, k of layer 1, i.e., σ ═ d (mean | d)_1,kI))/0.6745, where mean | d_1，kAnd | represents taking the intermediate value of all the wavelet transform coefficients d1, k amplitude of the layer 1.

The formula (3) and the formula (4) each have advantages and disadvantages. The function of equation (3) is to change the wavelet coefficients with absolute values smaller than the threshold to zero and to retain the wavelet coefficients with absolute values larger than the threshold. Since the function is discontinuous, the reconstructed signal oscillates. The function of the formula (4) is not completely reserved when processing the wavelet coefficients with the absolute value larger than the threshold value, but is subjected to contraction processing, namely, the coefficients are reduced, because the function is a continuous function, the defect of the function of the formula (3) is better overcome, but the method always has constant deviation when reducing the wavelet coefficients with the larger absolute value, and the approximation degree of the reconstructed signal and the original signal is directly influenced. Therefore, to obtain a more accurate threshold function, a variable threshold is applied to Thr, see equation (5).

The Thr threshold is calculated by adopting a formula (5):

in the formula (5), j is the current number of decomposition layers. Nj is the length of the wavelet coefficient for the current decomposition level, σ is the standard deviation of the signal, which needs to be estimated from the noisy signal, σ ═ d (mean | d)_1,k|)/0.6745。

In order to eliminate the disadvantages of the soft and hard threshold functions, a new threshold function is reconstructed in the present embodiment, as shown in formula (10):

in the formula (10), d_j,kThe coefficients of the original wavelet are then compared,

is the wavelet coefficient processed by the threshold function, a is more than or equal to 0, and Thr is the threshold.

When a is 0, expression (10) is equivalent to a hard threshold function, and when a is infinity, expression (10) is equivalent to a soft threshold function. In equation (10), as in the new threshold function, as d_j,kThe increase in the number of the first and second,

increasingly closer to d_j,kNot only overcoming d in the soft threshold function_j,kAnd

the disadvantage of constant deviation, and also overcomes d in the hard threshold function_j,kAnd

without the disadvantage of bias. Under the condition of adopting a variable threshold and constructing a new threshold function, a larger denoising effect can be obtained.

the above is the step of removing the echo noise of the ultrasonic wave by using the wavelet change in this embodiment, and here, a better denoising effect can be obtained by using the wavelet basis, the vanishing moment, the number of decomposition layers, the threshold function and the threshold, so that the micro-processing controller can obtain a better echo signal, and further confirm a more accurate time of receiving the echo.

Under normal temperature and pressure, the propagation speed of the ultrasonic wave in the air is about 340.2 m/s. Compared to other transmission media, such as humidity, pressure, ultrasound is more sensitive to changes in temperature. The propagation velocity of the ultrasonic wave in air can be expressed as:

in formula (8), wherein: gamma is the ratio of the specific heat capacity of air (the ratio of constant pressure heat capacity to constant volume heat capacity), and gamma is 1.4; ideal gas constant in R air, R is 8.134kg^-1K^-1(ii) a Mu is air molar mass 0.00283kg mol^-1(ii) a T is the absolute temperature of the gas, and T is the temperature in centigrade;

according to equation (8), the transmission rate in equation (8) is subjected to taylor series expansion with high-order terms omitted, γ being 1.4 and R being 8.134kg^-1K^-1，μ＝0.00283kg mol^-1The ultrasound velocity available is:

and C is 331.5+0.607t (m/s), and t is the current ambient temperature.

Specifically, the environmental humidity also has an influence on the ultrasonic transmission rate, and therefore, not only the temperature but also the humidity are considered, and through analysis and verification, the formula (9) is adopted:

in formula (9): t ═ T +273.15, TIs the absolute temperature of air, t is the temperature in centigrade; gamma is the specific heat capacity of air; p₀The pressure of the humid air;

relative humidity of the humid air, Psb is saturated water vapor partial pressure; wherein Psb can be obtained by directly referring to the humid air property table or by using the formula of the calculation formula Hyland-Wexler of the humid air state parameter. Po and

the environment is measured by a pressure sensor and a humidity sensor.

Preferably, in this embodiment, (8) or (9) is selected according to the requirement for the accuracy of the distance. When the allowable ranging error does not exceed 4%, the transmission rate of the ultrasonic wave only needs to be calculated according to the formula (8), otherwise, the transmission rate of the ultrasonic wave is calculated by using the formula (9).

Effects and effects of the examples:

compared with the prior art, the technical scheme in the implementation can obtain the following beneficial effects:

the invention provides an image display method of a vehicle electronic rearview mirror, which processes and displays corresponding visual field images according to a preset optimization mode according to vehicle signals, such as sensor signals and vehicle state signals, through video images in a plurality of preset acquisition directions around a collected vehicle, reduces left and right blind areas seen by a driver in a driving process, displays images around a vehicle body with wider visual angle range through a display screen in the vehicle based on driving operation signals through a camera and a related image control unit, achieves the aim of optimizing display, and improves the safety and comfort of the user driving the vehicle

In addition, by using the vehicle-mounted Ethernet technology, the image information displayed on the display screen can be clearer and more real-time;

in addition, the two display screens are used for respectively displaying images in front of the vehicle and behind the vehicle on the left and right sides, and the two display screens are respectively arranged on the left side and the right side in the vehicle, so that the use habits of the existing users are met, and the display of all the images on the two display screens is easier to be accepted by the users compared with the display of all the images on the single display screen.

In addition, in the danger early warning system, the ultrasonic waves are utilized to carry out distance measurement on the vehicle and the target obstacle, and the influence of factors such as ultrasonic echo noise, temperature and humidity is considered in the distance measurement process, so that better measurement accuracy is obtained. Such as: the influence of the ambient temperature and the humidity on the ultrasonic transmission rate is considered in the ultrasonic ranging, and the ranging precision between the vehicle and the current barrier is improved, so that the safety early warning or the automatic braking distance can be provided.

Such as: when the ultrasonic wave is adopted for ranging, because signal interferences such as thermal noise, bottom clutter and the like exist, the ranging precision is greatly reduced, the general wavelet threshold value method improves parameters in the method, constructs a threshold value function, considers the influence of the ambient temperature and humidity on the ultrasonic wave transmission rate for the ultrasonic ranging, improves the ranging precision between a vehicle and the current obstacle, and can provide prepared safety early warning or automatic braking distance.

Claims

1. An image display and danger early warning method for a vehicle electronic rearview mirror is characterized by comprising the following steps:

the method at least comprises the following steps:

displaying a plurality of video images to a driver;

in the forward driving mode, the images displayed by the display screen are as follows: displaying the video image collected at the front left at a normal visual angle, displaying the video image collected at the rear left at a wide-angle visual angle, displaying the video image collected at the front right at a normal visual angle, and displaying the video image collected at the rear right at a wide-angle visual angle;

in the left turn mode, the images displayed by the display screen are as follows: displaying the video images collected at the left front and the left rear at a wide angle of view, displaying the video image at the right front at a normal angle of view, and displaying the video image at the right rear at a wide angle of view;

in the right turn mode, the images displayed by the display screen are as follows: displaying the video images collected at the front left side at a normal visual angle, displaying the video images collected at the rear left side at a wide-angle visual angle, and displaying the video images collected at the front right side and the rear right side at the wide-angle visual angle;

in the reverse mode, the images displayed by the display screen are as follows: displaying the video images collected at the front left and the rear left at a wide angle of view, and displaying the video images collected at the front right and the rear right at a wide angle of view;

the method further comprises a danger early warning method:

step B1: acquiring a target distance between the vehicle and the obstacle through ultrasonic ranging; wherein the ultrasonic ranging comprises the denoising processing of echo signals,

step B2: judging whether the target distance is smaller than a safe distance M1, if so, executing a step B3, otherwise, continuously judging whether the new target distance is smaller than M1;

step B3: starting voice early warning;

step B5: starting a buzzing early warning;

step B6: the emergency automatic stop of the vehicle is carried out,

the denoising processing of the echo signal comprises the following steps: selecting threshold function, and applying wavelet coefficient d to each layer_j,kThresholding is carried out, scale coefficient c_j,kKeeping the threshold value constant, selecting one of the formula (3) or the formula (4) by the threshold value function,

in the formula (5), j is the current decomposition layer number, Nj is the length of the wavelet coefficient of the current decomposition layer number, and sigma is the standard deviation of the signal;

wherein the threshold function is:

wherein d is_j,kThe coefficients of the original wavelet are then compared,

is the wavelet coefficient processed by the threshold function, a is more than or equal to 0, Thr is the threshold value, and sgn is the step function.

2. The image display and danger early warning method for the vehicle electronic rearview mirror as claimed in claim 1, wherein:

the vehicle signal comprises any at least one of: driving operation signals, sensor signals, vehicle state signals.

3. The image display and danger early warning method for the vehicle electronic rearview mirror according to claim 2, characterized in that:

the driving operation signal includes: forward running, left turning, right turning and reverse running,

the normal or optimized video image processing mode is correspondingly set and stored for the driving operation signals in different preset acquisition directions,

the plurality of predetermined acquisition directions comprises: the left front direction, the left rear direction, the right front direction and the right rear direction of the vehicle.

4. The image display and danger early warning method for the vehicle electronic rearview mirror according to claim 1, characterized in that:

the method for displaying a plurality of video images to a driver includes:

the normal display mode of the video image comprises the following steps: the angle of visibility is within 60,

the wide-angle optimization mode of the video image comprises the following steps: the angle of visibility is greater than 120.

5. The image display and danger early warning method for the vehicle electronic rearview mirror according to claim 1, characterized in that:

the image processing unit comprises a main controller, a communication interface in communication connection with the camera, an in-vehicle data interface in communication connection with other in-vehicle external equipment, and an image output unit in communication connection with the display screen, wherein the main controller is respectively connected with the image output unit, the in-vehicle data interface and the communication interface.

6. The image display and danger early warning method for the vehicle electronic rearview mirror as claimed in claim 1, wherein the image display method comprises the following specific steps:

step S5, entering the state, judging that the driving operation signal of the vehicle is in a reverse mode, displaying the video image as a left front wide angle, a left rear wide angle, a right front wide angle and a right rear wide angle by the main controller, and entering the step S6;

step S6, judging whether the data interface in the vehicle receives the steering signal, if so, indicating that the vehicle is steered, entering step S7, if not, indicating that the vehicle is not steered, entering step S11;

7. The image display and danger early warning method for the vehicle electronic rearview mirror as claimed in claim 1, wherein:

in step B1, the step of obtaining the target distance between the vehicle and the obstacle through ultrasonic ranging specifically includes the steps of:

step B13: the reflected ultrasonic echo can be received by the receiving sensor and is subjected to signal processing through the receiving circuit, and the denoising processing of the echo signal is performed through the micro-processing controller or the receiving circuit;

step B14: the micro-processing controller obtains the target distance according to the time difference between the sending and receiving of the ultrasonic waves and the transmission rate of the ultrasonic waves.

8. The image display and danger early warning method for vehicle electronic rearview mirrors as claimed in claim 7, wherein:

in step B13, the denoising processing of the echo signal includes the following steps:

step B131:

establishing an expression (1):

x(i)＝s(i)+n(i) (1)

in formula (1), i is 0, 1, …, N-1, x (i) is a function of noisy signals, s (i) is a function of useful signals, and N (i) is a function of noise;

step B133: selecting the number J of decomposition layers, and performing orthogonal wavelet transform on the signal by using the formula (2) to obtain the scale coefficient c of each layer_j,kSum wavelet coefficient d_j,k，

In the formula (2), k is 0, 1, …, R-1, J is 0, 1, …, J, J is the number of decomposition layers, R is the number of signal sampling points, h and g are mutually orthogonal filter banks, and n is the number of discrete sampling points;

step B134: selecting threshold function, and applying wavelet coefficient d to each layer_j,kThresholding is carried out, scale coefficient c_j,kKeeping the threshold value constant, selecting one of the formula (3) or the formula (4) by the threshold value function,

is the wavelet coefficient processed by the threshold function, Thr is the threshold,sgn is a step function; the Thr threshold is calculated by adopting a formula (5):

in the formula (7), the scale factor c of each layer_j,kSum wavelet coefficient d_j,kK is 0, 1, …, R-1, J is 1, 2, …, J is the number of decomposition layers, R is the number of signal sampling points, and n is the number of discrete sampling points; h and g are each a quadrature filter bank.

9. The image display and danger early warning method for vehicle electronic rearview mirrors as claimed in claim 7, wherein:

in step B14, the formula for calculating the transmission rate of the ultrasonic wave adopts one of the following formula (8) or formula (9):

in formula (8), wherein: c is the ultrasonic velocity, and gamma is the air specific heat ratio; r ideal gas constant in air; mu is air molar mass; t is the absolute temperature of the gas, and T is the temperature in centigrade;

in formula (9): c is the ultrasonic velocity, T is T +273.15, T is the absolute temperature of air, and T is the temperature in centigrade; gamma is the specific heat capacity of air; p₀The pressure of the humid air;

10. The image display and danger early warning method for the vehicle electronic rearview mirror as claimed in claim 1, wherein: in the step B2, the value range of the safe distance M1 is 0.5-1M, and the value range of the dangerous distance M2 is 0.2-0.3M.

11. The image display and danger early warning method for vehicle electronic rearview mirrors according to claim 8, wherein when the SNR is less than or equal to 20dB, J is 2-4 or SNR is more than 20dB, and J is 3.

12. The utility model provides an image display and dangerous early warning equipment of vehicle electron rear-view mirror which characterized in that:

an image display device including an electronic rearview mirror for a vehicle and a hazard warning device,

the image display device of the electronic rearview mirror for a vehicle includes:

the display screen displays a plurality of video images facing a driver;

an image processing unit for processing and displaying the corresponding view field image according to the vehicle signal and a preset optimization mode,

the image processing unit includes at least a main controller;

the danger early warning apparatus includes:

the transmitting circuit is connected with the transmitting sensor, the receiving circuit is connected with the receiving sensor,

the micro-processing controller is also connected with a main controller in the image processing unit,

the danger early warning device also comprises a temperature sensor and a humidity sensor which are used for detecting the temperature and the humidity outside the vehicle, the temperature sensor and the humidity sensor are respectively connected with the micro-processing controller,

the danger early warning device is also used for acquiring a target distance between the vehicle and the obstacle through ultrasonic ranging; the ultrasonic ranging comprises denoising processing of echo signals, wherein the denoising processing of the echo signals comprises: selecting threshold function, and applying wavelet coefficient d to each layer_j,kThresholding is carried out, scale coefficient c_j,kKeeping the threshold value constant, selecting one of the formula (3) or the formula (4) by the threshold value function,

wherein the threshold function is:

wherein d is_j,kThe coefficients of the original wavelet are then compared,