RU2683715C1 - Rear collision early warning system and method based on visible light communication - Google Patents

Abstract

FIELD: physics.SUBSTANCE: group of inventions relates to a rear collision early warning system based on visible light communication. Rear collision early warning system based on visible light communications comprises a positioning module, an MCU, an optical-link modulation module, an LED lamp, a photosensitive receiver, and an HMI system. Positioning module, optical-link modulation module, photosensitive receiver and HMI system are connected to the MCU separately, and the LED lamp is connected to the optical-link modulation module. Early warning system is mounted on a vehicle moving ahead and approaching from behind. Vehicle approaching from behind sends information to a vehicle moving ahead in an active way, so that a vehicle moving ahead can receive additional status information on the vehicle approaching from behind.EFFECT: improved road safety is achieved.3 cl, 15 dwg

Description

Cross reference to related applications

[0001] This application claims priority to patent application (China) No. 201510130071.8, entitled "REAR-END COLLISION EARLY-WARNING SYSTEM AND METHOD BASED ON VISIBLE LIGHT COMMUNICATION", filed March 24, 2015 with the State Intellectual Property Office of the People's Republic of China the contents of which are fully incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention relates to electronic vehicle control technology, and in particular, to a rear collision early warning system and method based on communication in the visible light range.

State of the art

[0003] An accident due to a rear collision is the most characteristic automobile accident. In China, the frequency of accidents due to a rear collision is one third of the total frequency of road crashes, resulting in a huge number of accidents and economic losses. In order to reduce the frequency of accidents due to a rear collision and to improve vehicle safety performance, the rear collision early warning system is increasingly being applied to the vehicle. When there is a potential risk of a rear collision, early warning of rear collisions is provided to the vehicle to facilitate measures for the driver, such as acceleration or taxiing, in order to prevent rear collisions or reduce injuries.

[0004] A conventional rear collision early warning system is generally a rear collision early warning system based on a radar. Thus, the radar is mounted at the rear of the vehicle, and a vehicle approaching from behind, which quickly approaches the vehicle in the same lane, is detected by the radar. As shown in FIG. 4, in the process of driving, the system continues to detect a distance between the vehicle and the other vehicle that approaches the vehicle and is located directly behind the vehicle, and continues to determine whether or not there is a danger of a rear collision. If the time before a collision (TTC) of a vehicle approaching from behind, which quickly approaches a vehicle in an identical lane, is less than the threshold time value, the system transmits an early warning of collisions from behind, i.e. tightens the seat belt or illuminates the early warning indicator light.

[0005] However, a radar-based rear collision early warning system has the following disadvantages.

[0006] (1) The approaching vehicle may be a car or truck, etc. Dynamic characteristics such as longitudinal acceleration, braking and steering characteristics of different types of approaching vehicles are different, and TTC situations must be calibrated differently. However, the rear-end collision warning system based on the radar adopts an active detection method, can only detect distance information and speed information of a vehicle approaching from behind, but cannot receive additional information regarding a vehicle approaching from behind. Therefore, a suitable TTC threshold and a suitable alarm time cannot be set dynamically based on a type approaching from behind the vehicle.

[0007] (2) A rear-end collision warning system based on a radar can only detect vehicles directly behind the vehicle. Refer to FIG. 4. In the case of a bend in the road, the vehicle 12 in the adjacent lane is detected by the radar wave 13 of the vehicle 10, and therefore an alarm signal may be generated relative to the vehicle in the adjacent lane by mistake. Despite this, a rearward-moving vehicle 11 in the same lane with the vehicle 10 cannot be detected by the radar wave 13 of the vehicle 10, and therefore there is a false negative judgment regarding a potential rear collision.

Disclosure of invention

[0008] An object of the present invention is to provide a rear collision early warning system and method based on communication in the visible light range. The vehicle approaching from the rear transmits information to the vehicle moving in front by means of an active method to make it easier for the vehicle moving in front to obtain additional information about the condition of the vehicle approaching from the rear, which ensures the accuracy of early warning of collisions from behind the vehicle moving in front. In addition, the corresponding TTC threshold value is selected for early warning of collisions in the rear of a vehicle in front of a vehicle based on the type of vehicle approaching in the rear, in order to more accurately determine.

[0009] A rear collision early warning system based on visible light communication is provided according to the present invention. The system includes a positioning module, an MCU, an optical communication modulation module, an LED lamp, a photosensitive receiver, and an HMI system.

[0010] The positioning module is configured to receive position information, heading information and orientation information when driving the vehicle in question and transmit it to the MCU. The positioning module is connected to the MCU.

[0011] The MCU is configured to obtain a vehicle driving state, a load state and vehicle type information from a tire of a vehicle in question, calculate a chronological path based on the position information of the vehicle in question, and transmit a chronological path, a vehicle driving state means, load status and information about the type of vehicle in the modulation module in optical communication. The optical modulation module is connected to the MCU.

[0012] The optical communication modulation module is configured to modulate a chronological path, a vehicle driving state, a load condition and vehicle type information, and drive the LED lamp so that it blinks. The LED lamp is connected to the modulation module in optical communication.

[0013] The LED lamp is mounted at the head of the vehicle and configured to generate an optical signal including a chronological path, a vehicle driving state, a load state and vehicle type information for the vehicle in question, and transmit an optical signal.

[0014] The photosensitive receiver is mounted at the rear of the vehicle and configured to receive an optical signal including a chronological path, a vehicle driving state, a load condition, and vehicle type information for a vehicle approaching from behind, transmitted by an LED lamps of a vehicle approaching from behind, adjust and demodulate the received optical signal and before Vat optical signal to the MCU. The photosensitive receiver connects to the MCU.

[0015] The MCU is configured to calculate the predicted route of the vehicle in question based on position information, heading information, and orientation information when driving the vehicle in question and determine whether or not the vehicle in question is in the same lane with approaching from behind vehicle, based on position information and the forecast route of the vehicle in question and based on position information and chronol the path of the vehicle approaching from behind. If the vehicle in question is in the same lane with the vehicle approaching from behind, the MCU is configured to calculate the TTC (namely, the time before the collision) between the vehicle in question and the vehicle approaching from the rear based on the distance and relative speed between the two vehicles means, calculate the maximum deceleration value selected for the vehicle approaching from behind, based on information about the type of trans tailor means and the load state of the vehicle approaching from behind and select a threshold TTC value based on the maximum deceleration value. If the TTC is less than the threshold TTC during the delay time period exceeding the preset threshold time, the MCU is configured to output early warning to the HMI system of the vehicle in question (i.e., a system with a human-machine interface), to perform early driver alerts. The HMI system connects to the MCU.

[0016] The LED lamp is an LED daytime running lamp or an LED head light.

[0017] A rear collision early warning method based on visible light communication according to the present invention is provided. A rear collision early warning system based on communication in the visible light range is installed both in the vehicle moving in front and in the vehicle approaching from behind. The method includes step 1 and step 2.

[0018] In step 1, during the driving process, the rear-approaching vehicle positioning module obtains position information of the rear-approaching vehicle, and the rear-approaching vehicle MCU calculates a chronological path of the rear-approaching vehicle based on the position information of the rear-approaching vehicle facilities. The MCU of the vehicle approaching from the rear receives the driving state and the load state of the vehicle approaching from the rear from the vehicle tire and transmits position information, a chronological path, the driving state, the load state and vehicle type information of the vehicle approaching the rear of the vehicle to the module modulation in optical communication of a vehicle approaching from behind. The optical modulation module encodes the information and drives the LED daytime running lamp or the LED headlight of a vehicle approaching from behind in such a way that it flashes and generates an optical signal including position information, a chronological trajectory, and the driving state , the load status and vehicle type information for the vehicle approaching from behind, and transmits an optical signal.

[0019] In step 2, when receiving an optical signal transmitted by a vehicle approaching from the rear, the photosensitive receiving device of the front-moving vehicle adjusts and demodulates the received optical signal. The front-vehicle MCU calculates the predicted route of the front-moving vehicle based on position information, heading information, and orientation information when driving the front-moving vehicle and determines whether or not the front-moving vehicle is in the same lane with the approaching behind the vehicle, based on information about the position and forecast route of the vehicle moving in front, and based on information and the position and chronological trajectory of the vehicle approaching from behind. If the vehicle in front is in the same lane with the vehicle approaching from the rear, the MCU calculates the TTC between the vehicle moving ahead and the vehicle approaching from the rear based on the distance and relative speed between the two vehicles and calculates the maximum deceleration value selected for a vehicle approaching from behind, based on information about the type of vehicle and the state of load approaching with rear of the vehicle. The MCU selects the TTC threshold value based on the maximum deceleration value. In the event that the TTC is less than the TTC threshold for a delay time period exceeding a predetermined time threshold, the MCU outputs an early warning to the HMI system of the vehicle in front to perform early warning of the driver of the vehicle in front.

[0020] The vehicle approaching from the rear includes a system of adaptive headlight lamps. Thus, the LED head light lamp can adaptively adjust direction according to bending.

[0021] The present invention has the following advantages.

[0022] (1) A rear-approaching vehicle transmits information to a front-moving vehicle in an active manner to make it easier for a front-moving vehicle to obtain additional information about the state of a rear-approaching vehicle, which ensures accurate early warning of collisions from a rear-facing vehicle.

[0023] (2) The most appropriate TTC threshold is selected for early warning of collisions in the rear of a vehicle in front of a vehicle based on the type of vehicle approaching from behind in order to make a more accurate determination.

[0024] (3) The present invention determines whether or not a vehicle approaching from the rear is in the same lane with a vehicle moving in front by comparing the chronological path of the vehicle approaching from the rear with the predicted route of the vehicle moving in front, which is equally applicable in case the vehicle moves along a bend. Therefore, incorrect information caused by vehicles traveling through a bend does not occur.

[0025] (4) The system is combined with the AFS system (adaptive headlights). Since the LED head light lamp can be adaptively adjusted according to the bend, and information regarding the vehicle approaching from the rear can also be transmitted to the vehicle in front of the vehicle in the bend, thereby reducing false-negative judgments regarding collisions from the rear in the bend.

[0026] (5) The system is combined with a lighting system (LED daytime running lamp or LED headlight) of the vehicle, which does not affect the normal operation of the lighting system and reduces costs due to the installation of a radar in a traditional rear collision early warning system.

Brief Description of the Drawings

[0027] FIG. 1 is a structural block diagram of a rear collision early warning system based on visible light communication according to the present invention;

[0028] FIG. 2 is a flow chart of using a rear collision early warning method based on visible light communication according to the present invention;

[0029] FIG. 3 is a state diagram of using a rear collision early warning method based on visible light communication according to the present invention;

[0030] FIG. 4 is a state diagram of using conventional technology;

[0031] FIG. 5 is a structural block diagram of an optical communication modulation module according to the present invention;

[0032] FIG. 6 is a block diagram of the pin terminals of the CPU processor of FIG. 5;

[0033] FIG. 7 is a schematic diagram of the connection between the CPU processor and the automobile LIN bus of FIG. 5;

[0034] FIG. 8 is a block diagram for the voltage conversion circuit of FIG. 5;

[0035] FIG. 9 is a block diagram for the forward voltage test circuit of FIG. 5;

[0036] FIG. 10 is a block diagram for a constant voltage controlled circuit in FIG. 5;

[0037] FIG. 11 is a structural block diagram of a photosensitive receiver according to the present invention;

[0038] FIG. 12 is a circuit diagram for the photoelectric conversion circuit of FIG. eleven;

[0039] FIG. 13 is a circuit diagram for the excess averaging circuit in FIG. eleven;

[0040] FIG. 14 is a circuit diagram for a lowpass filter circuit of FIG. eleven; and

[0041] FIG. 15 is a flowchart for a process for a microcomputer processor to calculate an optimal spatial reception angle according to the present invention.

[0042] Each of the arrows in FIG. 2, FIG. 3 and FIG. 4 indicates the direction of travel of the vehicle.

The implementation of the invention

[0043] The invention is described in detail below in conjunction with the drawings.

[0044] Referring to FIG. 1. A rear impact early warning system is provided based on visible light communication according to the present invention. The system includes a positioning module 4, MCU 3 (i.e., a microcontroller), an optical modulation module 2, an LED lamp 1, a photosensitive receiving device 5, and an HMI system 6 (for example, a dashboard, a buzzer on the dashboard and safety belt). LED lamp 1 is sold as a daytime running lamp.

[0045] The positioning module 4 consists of a satellite positioning system and a gyroscope. The positioning module 4 is configured to receive position information, heading information and orientation information when driving the vehicle in question and transmit it to the MCU 3, and the positioning module 4 is connected to the MCU 3.

[0046] the MCU 3 is configured to receive a vehicle driving state (for example, speed and braking state), a load state and vehicle type information (for example, a heavy truck, light truck, bus, minibus and passenger car that is stored in the vehicle controller) from the tire of the vehicle in question, calculates a chronological path based on the position information of the vehicle in question and transmits the chrono ogicheskuyu trajectory state driving of the vehicle, the load status and information on the type of vehicle in module 2 modulation in optical communication. The optical modulation module 2 is connected to the MCU 3.

[0047] The optical modulation module 2 is configured to modulate a chronological path, a vehicle driving state, a load condition, and vehicle type information, and drive a daytime running light so that it flashes at a high frequency in order to generate an optical signal 9. The LED daytime running lamp is connected to the modulation module 2 in optical communication.

[0048] An LED daytime running lamp is mounted in the head of the vehicle and configured to generate an optical signal 9 including a chronological path, a vehicle driving state, a load condition, and vehicle type information for the vehicle in question, and transmit an optical signal.

[0049] The photosensitive receiver 5 is mounted in the rear of the vehicle and configured to receive an optical signal 9 including a chronological path, a vehicle driving state, a load condition, and vehicle type information for a vehicle approaching from behind, 8 transmitted by an LED lamp, daytime running lights approaching from behind the vehicle 8, adjust and demodulate received 9, the optical signal and transmit the optical signal to the MCU 3. The photosensitive receiving device 5 is connected to the MCU 3.

[0050] The MCU 3 is configured to calculate the predicted route of the vehicle in question based on position information, heading information and orientation information when driving the vehicle in question and determine whether or not the vehicle in question is in the same lane with the approaching behind the vehicle 8, based on position information and the forecast route of the vehicle in question and based on position information and chron the path of the vehicle approaching from behind the vehicle 8. If the vehicle in question is in the same lane with the vehicle approaching from behind, the MCU 3 is configured to calculate the TTC (namely, the time before the collision) between the vehicle and the vehicle approaching from behind means 8, based on the distance and relative speed between the two vehicles, calculate the maximum deceleration value selected for izhayuschegosya rear of the vehicle 8, based on information about the type of vehicle and the load condition of the approaching rear vehicle 8 and select the threshold value based on the TTS maximum deceleration value. In case the TTC is less than the TTC threshold for a delay time period exceeding a predetermined time threshold, the MCU 3 is configured to output an early warning to the vehicle HMI system b in order to perform an early warning to the driver. HMI system 6 connects to MCU 3.

[0051] In the rear collision early warning system based on visible light communication according to the present invention, the LED lamp 1 can alternatively be a LED head light.

[0052] Referring to FIG. 2 and FIG. 3, which show a rear collision early warning method based on visible light communication according to the present invention. A rear collision warning system based on communication in the visible light range is installed both in the vehicle ahead of the vehicle 7 and the vehicle 8 approaching from the rear, and at least the vehicle 8 approaching from the rear includes an AFS system (adaptive headlights ) The method includes step 1 and step 2.

[0053] In step 1, during the driving process, the rear-approaching vehicle positioning unit 4 receives information about the position of the rear-approaching vehicle 8, and the MCU 3 of the rear-approaching vehicle 8 calculates a chronological trajectory of the rear-approaching vehicle 8 based on the information about the position of the vehicle approaching from behind 8. MCU 3 of the vehicle approaching from behind 8 receives the state of propulsion and the load state located behind the vehicle 8 from the vehicle tire and transmits position information, a chronological trajectory, the driving state, the load state and vehicle type information for the vehicle approaching from the rear of the vehicle 8 to the modulation module 2 in optical communication of the vehicle approaching from the rear of the vehicle 8. The optical modulation module 2 encodes information and drives an LED daytime running lamp or an approaching LED headlight lamp behind the vehicle 8 so that it blinks and generates an optical signal 9, including position information, a chronological trajectory, the driving state, the load state and vehicle type information for the vehicle approaching behind the vehicle 8, and transmits an optical signal .

[0054] In step 2, when receiving an optical signal 9 transmitted by a rear-facing vehicle 8, the photosensitive receiving device 5 of the front-moving vehicle 7 modulates and demodulates the received optical signal 9. The MCU 3 of the front-moving vehicle 7 calculates a predicted path of the front-moving vehicle vehicle 7 based on position information, heading information and orientation information when driving the vehicle 7 in front and determines whether or not the front-running vehicle 7 is in an identical lane with the rear-facing vehicle 8, in combination with the position information and the forecast route of the front-moving vehicle 7, and in combination with the position information and the chronological path of the rear-approaching vehicle 8. If the vehicle in front is in the same lane with the vehicle 8 approaching from the back, MCU 3 calculates the TTC between the front of the vehicle 7 and the rear of the vehicle 8 based on the distance and the relative speed between the two vehicles and calculates the maximum deceleration value selected for the rear of the vehicle 8 based on information about the type of vehicle and the load condition of the rear of the vehicle 8. MCU 3 selects the TTC threshold value based on the maximum deceleration value. If the TTC is less than the threshold TTC for a delay time period longer than the preset time threshold, the MCU 3 outputs an early warning to the HMI system 6 of the vehicle in front of the vehicle 7. The HMI system 6 drives the device of the vehicle in front of the vehicle 7 in such a way that it carries out a warning in the form of an image, activates the buzzer in such a way that it gives an audible alarm, and activates the seat belt so that n vibrates, due to this, performing an early warning to the driver of the vehicle ahead of the vehicle 7.

[0055] Referring to FIG. 3. The present invention determines whether or not the vehicle approaching from the rear is in the same lane with the vehicle moving in front, by comparing the chronological trajectory of the vehicle approaching from the rear 8 with the predicted route of the vehicle moving ahead 7, which is equally applicable in the case of if the vehicle is bending. Therefore, incorrect information caused by vehicles traveling through a bend does not occur.

[0056] Referring to FIG. 3. The vehicle approaching from the rear 8 includes a system of adaptive headlights. Thus, the LED head light can adaptively adjust the direction according to the bend, and in the bend, information regarding approaching from the rear of the vehicle 8 can be transmitted to the front moving vehicle 7, thereby reducing false-negative judgments regarding collisions from behind on the bend.

[0057] The optical communication modulation module 2 in the present invention is implemented using conventional technology, for example, a transmitting device for driving an LED optical lamp based on the optical communication disclosed in the invention, the application number of which is 2014205836509. FIG. 5 shows a transmitting device, which includes a CPU processor 21, which performs the role of data processing, control and output, and a voltage conversion circuit 25 configured to provide a driving current to the LED lamp 1. CPU processor 21 (modulation module 2 in optical communication, it may not use the CPU-processor separately and can control and process data via the MCU 3 in the rear collision early warning system) is functionally connected to the vehicle’s LIN / CAN bus 22 cutting an interface circuit 23 to receive optical communication information content. The voltage conversion circuit 25 modulates the transmitted data transmitted by the CPU processor 21 into a lighting current in the form of a high level and a low level. The high-frequency semiconductor switch 26, driven by the voltage conversion circuit 25, is a device for modulating a current waveform.

[0058] The LED lamp 1 comprises a forward voltage test circuit 24 configured to measure forward voltage drop. The output terminal of the forward voltage testing circuit 24 is connected to the CPU processor 21. The CPU processor 21 calculates the transition temperature of the LED lamp 1 based on the drop in the forward voltage and the temperature coefficient and outputs a digital reference level from the output terminal of the level in combination with the transmitted data. The output pin of the level of the CPU-processor 21 is connected to a digital-to-analog conversion circuit 28, a second low-pass filter circuit 29 and a constant voltage controlled circuit 27 in the above sequence and converts the reference level into an analog value. The output terminal of the constant-voltage controlled circuit 27 is connected to the voltage reference terminal of the voltage conversion circuit 25 to perform a linear AND operation. The output current of the voltage conversion circuit 25 is determined by the reference voltage, i.e. the high level and low level of the current waveform encoded by the transmitted data are determined by the reference voltage after the CPU processor 21 performs a fuzzy classification decision for the transition temperature and the transmitted data.

[0059] As a specific implementation scheme, the CPU 21 is a 16-bit single chip microcomputer of the Freescale type MC9S12XS128. The pin numbers corresponding to the pin terminals of the single-chip microcomputer are shown in FIG. 6. The pin terminals 50-52 of the single-chip microcomputer (which are LIN-RXD, LIN-TXD and LIN-EN) are connected to the vehicle’s LIN bus via the LIN control signal generator Tires, the type of which is MC33661. As shown in FIG. 7, the pin terminal 45 of a single-chip microcomputer (i.e., the pin terminal PAD06) is a forward voltage input terminal, and the configuration of the other pin terminals is referred to in FIG. 6.

[0060] The voltage conversion circuit 25 includes an LED drive controller of the type of LM3421. The pin configuration of the LM3421 is shown in FIG. 8. The pin 8 of the LM3421 (i.e., pin nDIM) is connected to the pin 63 (i.e., pin PWM7) of the single-chip microcomputer via a Q7 triode. Pin 7 (i.e., OVP pin) of the LM3421 is the pin of the reference voltage. Pin 12 (i.e., VCC pin) of the LM3421 connects to the base of the NPN triode Q4. Pin 9 (i.e., DDRV pin) of the LM3421 is connected to the emitter of the triode Q4, and the collector of the triode Q4, respectively, is connected to the bases of the NPN triode Q2 and PNP triode Q3. The collector of the triode Q2 is connected to the base resistor, the emitter of the triode Q2 is connected to the emitter of the triode Q3, and the collector of the triode Q3 is connected to the base of the PNP triode Q6, also connected to the supply voltage and connected to the base through the diode. The emitter of the triode Q6 is connected to the collector resistor of the triode Q2, and the collector of the triode Q6 is connected to the pin 7 (i.e., OVP pin) of the LM3421 and is grounded through the resistor.

[0061] In order to prevent the abnormal operation of the switching power supply, so that the lighting function is turned off, which is caused by the convergence that occurs during the control of the voltage conversion circuit 25, the high-frequency semiconductor switch 26, configured to modulate a variable square wave, includes a transistor Ql with high electron mobility based on GaN, the switching frequency of which is less than one tenth of the operating frequency of a switching power supply. In order to prevent visual distortion of the performance, the operating frequency Ql is preferably greater than 200 Hz. The G-electrode Ql is connected to the emitter Q2, and the GaN-based diode D5 is connected between the D-electrode Ql and the pin 1 (contact terminal of the operating voltage) LM3421. The first resistor RSNS1 is connected to the S electrode Ql. The end of the first resistor RSNS1 connected to the S-electrode Ql is connected to the pin resistor 15 (i.e., the HSP pin) LM3421, and the other end of the first RSNS1 resistor is connected to the pin 16 (i.e. the HSN pin) LM3421 and supply voltage. The negative electrode of the diode D5 is connected to the collector Q2, and ILED1 representing the LED lamp 1 is connected between the negative electrode of the diode D5 and the collector Q2. The forward voltage test circuit 24 is configured to test the forward voltage drop of the LED lamp 1. The CPU 21 calculates a transition temperature based on the forward voltage drop and the temperature coefficient, the circuit structure of which is shown in FIG. 9. As shown in FIG. 10, the constant-voltage controlled circuit 27 consists of an operational amplifier LM358 and a field effect transistor and carries out a linear AND operation with a reference voltage Vref of the voltage conversion circuit 25. The digital-to-analog conversion circuit 28 and the second low-pass filter circuit 29 are implemented using a conventional module that is not described redundantly in this document.

[0062] A method for driving an optical communication LED automotive lamp is disclosed in the present invention as follows. The CPU processor 21 transmits the transmitted data to the voltage conversion circuit 25 in the form of a data frame for modulation. The voltage conversion circuit 25 modulates the transmitted data into direct current lighting in the form of a high level and a low level. The CPU 21 provides in time a reference voltage to the voltage conversion circuit 25 based on the transition temperature of the LED lamp 1 in combination with the driving parameter and the transmitted LIN / CAN data of the vehicle 22. The voltage-to-voltage conversion circuit 25 controls the high, level, and low level of the current waveform corresponding to the transmitted data based on the reference voltage. As factors that affect the effect of communication, factors such as the distance between two vehicles and the interference of ambient light should be considered. The light output of the lighting of the LED lamp 1 is influenced by factors such as the transition temperature and the driving current. In the event that the LED lamp 1 operates at a predetermined brightness of the lighting, the transmitted data must be modulated into the lighting current. The transmitted data is in the form of a high level and a low level, and a high level can reduce the light output of the LED lamp 1. Therefore, if both vehicles have a good communication reception effect, the difference between the high level and the low level of the current waveform is reduced, so that the current forcedly tends to be a constant current lighting, which allows to increase light output.

[0063] The transition temperature of the LED lamp 1 has a direct effect on its life and reliability. In order to reduce the transition temperature, the average current flowing through the LED lamp 1 is reduced while allowing the LED lamp 1 to operate at the prescribed lighting brightness. The transition temperature of the LED lamp 1 is calculated from the drop in direct voltage and temperature coefficient.

A dynamic control loop of the reference level is formed by estimating the transition temperature as a real-time feedback value in order to achieve controlled current control that drives the LED lamp 1 in such a way that it operates. Dynamic adjustment of the transition temperature, regardless of whether there is a connection or not, can provide a resource for the LED lamp 1. The transition temperature of the LED lamp 1 is measured and calculated by the forward voltage testing circuit 24, as described above.

в форме потока двоичных данных, за исключением светодиодной лампы 1 без связи. Чтобы не затрагивать нормальную функцию фотографирования, каждая из различных частот fi больше 1 кГц и меньше одной десятой частоты переключения мощности схемы 25 преобразования напряжения. С учетом влияния сложного распространения света на коэффициент битовых ошибок частотной демодуляции в приемной стороне, любая относительная разность частот в прямоугольном сигнале больше 1%, и относительная разность частот между смежными частотами не меньше 5%. Относительная разность частот задается как

, где f_i и f_j представляют две различных частоты прямоугольной волны тока кодирования.[0064] In addition to adjusting the current, the CPU 21 adjusts the frequency of the current waveform corresponding to the transmitted data in combination with the traffic parameter and the transmitted data of the vehicle LIN / CAN bus 22 to increase the transmission speed of the transmitted data and reduce the response time for vehicle communication. The transmitted data is combined and encoded by at least two rectangular signals of different frequencies

in the form of a binary data stream, with the exception of LED lamp 1 without communication. In order not to affect the normal photographing function, each of the various frequencies fi is greater than 1 kHz and less than one tenth of the power switching frequency of the voltage conversion circuit 25. Given the influence of complex light propagation on the bit error rate of the frequency demodulation in the receiving side, any relative frequency difference in a rectangular signal is more than 1%, and the relative frequency difference between adjacent frequencies is not less than 5%. The relative frequency difference is set as

where f _i and f _j represent two different frequencies of the square wave of the coding current.

[0065] The high level and low level of the current waveform corresponding to the transmitted data are weighted based on a fuzzy classification index. Weighting based on a fuzzy classification index is described in detail as follows.

, где

. В этом первичном состоянии, предусмотрено три случая расстояний между транспортными средствами.[0066] In the case where the transition temperature T _jn of the LED lamp 1 is greater than the threshold temperature T _th , the current waveform form I (k) at the current time t _k decays based on an exponential weight coefficient to obtain the form level I (k + 1) current signal next time that represents

where

. In this initial state, there are three cases of distances between vehicles.

[0067] (1) If the distance between the vehicles is greater than the upper threshold distance value of 30 meters and less than 300 meters, the initial level of illustration of the LED lamp 5 without transmitted data is I ₂ = I _avg , the initial high level I ₃ in the form the current signal corresponding to the transmitted data is 2I _avg , and the initial low level I ₁ is 0. The occurrence frequency I ₂ is 200 Hz, the occurrence frequency I ₁ is 20 kHz, and the occurrence frequency I ₃ is 21 kHz.

[0068] (2) If the distance between the vehicles is greater than the lower threshold distance value of 10 meters and less than the upper threshold distance value of 30 meters, the initial illumination level of the LED lamp 5 without transmitted data is I ₂ = I _avg , the initial high level I ₃ in the form of a current signal corresponding to the transmitted data is l, 5I _avg , and the initial low level I ₁ is 0.5I _avg . The occurrence frequency I ₂ is 1000 Hz, the occurrence frequency I ₁ is 500 kHz, and the occurrence frequency I ₃ is 510 kHz.

[0069] (3) If the distance between the vehicles is less than the lower threshold distance value of 10 meters, the initial illumination level of the LED lamp 5 without transmitted data is I ₂ = I _avg , the initial high level I ₃ in the form of a current signal corresponding to the transmitted data is l, 5I _avg , and the initial low level of I ₁ is 0.5I _avg . The occurrence frequency I ₂ is 0 Hz, the occurrence frequency I ₁ is 2000 kHz, and the occurrence frequency I ₃ is 210 kHz.

[0070] (4) If the distance between the vehicles is greater than the effective communication distance of 300 meters, the communication is terminated and the initial nominal lighting current of the LED lamp 5 is I ₂ = I _avg .

[0071] In addition to the above three cases of levels, additional levels can be precisely defined. When choosing a high level of the current waveform, the high level must be ensured in such a way that it is less than 5 times the rated current I _{avg of} illumination in order to prevent damage to the LED lamp 5 by excessive current. Preferably, the transition temperature control range of the LED lamp 5 is generally not more than 10%, and too large a control range is excluded, which causes the current of the LED lamp of the 5 daytime running lights to decrease too much, which does not satisfy the prescribed lighting brightness.

[0072] In the present invention, the life of the LED lamp is ensured by controlling the transition temperature, and reliable communication is provided between vehicles with different distances by adjusting the difference between the high level and low level of the current waveform in the data transmission. In an aspect, the luminous efficiency of illumination is increased at a prescribed illumination, and the effect of "uneven control" is minimized to protect circuit devices. In another aspect, the communication speed is increased by controlling the frequency, and the timeliness of communication is ensured.

[0073] As shown in FIG. 11, the photosensitive receiver 5 in the present invention can be implemented using conventional technology, for example, an adaptive receiver for an optical communication LED car lamp disclosed in the invention, the application number of which is 2014205712760. The adaptive receiver includes a photoelectric conversion module , a microcomputer processor 17 and a microelectromechanical mechanism 16.

The photodiode array 14 in the photoelectric conversion module is mounted on the microelectromechanical mechanism 16 as a device for receiving and converting an optical signal. The photodiode array 14 is in the form of a matrix of several diodes and can receive an optical signal in a wide range of angles. Several diodes output several electrical signals, which are amplified by a multi-channel amplifier circuit 15 to standard signals and are input to the microcomputer processor 17. Since the positions of the respective photodiodes relative to the source of emission of the optical signals are different, the intensity of the corresponding received signals is different. The microcomputer processor 17 recognizes and selects signals. In general, the device is movable with respect to the optical signal emitting source, and the microcomputer processor 17 controls the movement of the microelectromechanical mechanism 16 based on the signal reception and adjusts the reception angle of the photodiode array 14 to support the reception of tracking information in real time and to obtain the best signal.

[0074] In order to more accurately modulate the signal, the output of the microcomputer processor 17 is connected to a redundant averaging circuit 18 configured to process several signals into a single signal. The signal has a slight deviation and a high degree of similarity. The output of the excess averaging circuit 18 is connected to the first low-pass filter circuit 19. The output of the first lowpass filter circuit 19 is connected to the signal generating circuit 20. The signal is further cleared of noise and regularized to facilitate demodulation of the signal.

[0075] The microcomputer processor 17 selects a single-chip microcomputer whose processing performance is not lower than a single-chip microcomputer, the type of which is MC9S12XS128. The microelectromechanical mechanism 16 in the control output contact pin can select a MEMS system, the type of which is NM-XY-100X. Three output contact pins of the form of the PWM signal of a single-chip microcomputer are connected to the input pin of the microelectromechanical mechanism 16.

[0076] The photodiode array 14 includes several GaN-based photodiodes, which, during operation, may include six photodiodes D1-D6 distributed uniformly in each part. As shown in FIG. 12,. the positive electrode of each photodiode is connected to the operating voltage source Vcc. Resistors R1-R6 with identical resistance corresponding to the negative electrodes of the photodiodes D1-D6 are grounded. The negative electrodes of the six photodiodes are connected to six PAD pins of a single-chip microcomputer in a one-to-one correspondence via a six-channel amplifier circuit. The voltages in the negative electrodes of the photodiodes D1-D6 correspond to optical signals received by themselves, i.e. electrical signals after photoelectric conversion.

[0077] The excess averaging circuit 18 is a summation averaging circuit. As shown in FIG. 13, the summing averaging circuit 18 includes a comparison module of the type LM324C. The negative input terminal of the comparison module is grounded, and the positive input terminal of the comparison module is connected to the output terminal via resistor Rf. A single-chip microcomputer filters out biased signals from six signals in order to store four signals. Ports PA0-PA3 of a single-chip microcomputer are connected to the positive input terminal of the comparison module, respectively, through resistors R, Ra, Rb, and Rc. The output terminal V0 of the comparison module is connected to the input terminal of the first low-pass filter circuit 19 and another terminal PAD of a single-chip microcomputer.

[0078] The first low-pass filter circuit 19 and the signal generating circuit 20 can be implemented using conventional technology, for example, the first second-order low-pass filter circuit, as shown in FIG. fourteen.

[0079] An adaptive method for receiving a photosensitive receiver 5 in the present invention is as follows. The photodiode array 14 receives the optical signal emitted by the LED head light, and performs photoelectric conversion and mounts the photodiode array on the actuator of the microelectromechanical system. Several photodiodes of the photodiode array 14 receive and convert the optical signal in parallel and output electrical signals, the number of which corresponds to the number of photodiodes.

[0080] The microprocessor processor 17 processes several electrical signals output by the photodiode array 14. The microprocessor processor 17 calculates the degree of similarity or cross-correlation coefficient of each of the signals and removes the biased electrical signals in order to maintain effective electrical signals. For example, the photodiode array 14 outputs six electrical signals, filters out two electrical signals in order to store four electrical signals, and saves four electrical signals. Four electrical signals are processed and demodulated in real time.

[0081] The actuator actuates the photodiode array in such a way that it micro-moves in three-dimensional space at intervals. The magnitude of the micromotion is set as the input disturbance value. The microcomputer processor 17 calculates the similarity degrees of the electrical signal groups of the photodiode array 14 based on the method of observing disturbances before and after the disturbances, compares the similarity degrees of the electrical signal groups before and after the disturbances, and determines which of the electrical signal groups has the maximum similarity degree. The spatial angle of the photodiode array, corresponding to a group of electrical signals with a maximum degree of similarity, is set as the optimal reception angle and stored in the processor 17 of the microcomputer. The processor 17 of the microcomputer transmits information about the optimal angle of reception in the microelectromechanical system. The actuator adjusts the photodiode array to the optimum reception angle. The optimum reception angle is updated as each disturbance is introduced. The calculation processes are performed by the microcomputer processor 17 in program codes, and a flowchart of the method of program principles is shown in FIG. 15.

[0082] The above processing steps include over-averaging processing for an effective group of electrical signals to obtain a signal with a maximum degree of similarity. An ideal signal is obtained by low-pass filtering and generating a signal with a maximum degree of similarity, and then the process proceeds to the demodulation step. The magnitude of calculating the degree of similarity between groups of electrical signals is significant. To simplify the calculation and improve practicability, a signal with a maximum degree of similarity in the previous group of signals is used to represent a group of electrical signals, and is used to calculate and compare the degree of similarity. Therefore, the signal with the maximum degree of similarity is returned to the microcomputer processor 17 as a reference electrical signal for calculating the degree of similarity.

[0083] Further, a process for calculating an optimum spatial reception angle includes steps a-d.

[0084] In step a, it is assumed that the coordinate of the optimal spatial reception angle is (X ^opt , Y ^opt , Z ^opt ).

[0085] In step b, it is assumed that the coordinate of the reception angle before the kth disturbances are introduced is (X ₀ , Y ₀ , Z ₀ ), an effective group (V01, ..., V0n) of electrical signals is obtained by calculating the similarity or cross-correlation operation of a group of waveforms corresponding to an electrical signal. The signal V _k with the maximum degree of similarity is obtained by performing excessive averaging for the effective group (V01, ..., V0n) of electrical signals. The signal V _k with the maximum degree of similarity is compared with the signal V _k-1 with the maximum degree of similarity before the (k-1) th disturbances are introduced to obtain the degree f _{k-1 of} similarity.

[0086] In step c, kth disturbances are introduced. The magnitude of the perturbations is (ΔX ₀ , ΔY ₀ , ΔZ ₀ ). The coordinate of the reception angle after disturbances is (X ₀ + ΔX ₀ , Y ₀ + ΔY ₀ , Z ₀ + ΔZ ₀ ). An effective group (V11, ..., V1m) of electrical signals is obtained by calculating the similarity or cross-correlation operation of the group of waveforms corresponding to the electrical signal. The signal V _{k + 1} with the maximum degree of similarity is obtained by performing excessive averaging for the effective group (V11, ..., V1m) of electrical signals. The signal V _{k + 1} with the maximum degree of similarity is compared with the signal V _k with the maximum degree of similarity before the kth disturbances are introduced to obtain the degree of f _k similarity.

[0087] In step d, f _{k-1 is} compared with f _k . If f _{k-1 is} greater than f _k , (X ₀ , Y ₀ , Z ₀ ) is assigned (X ^opt , Y ^opt , Z ^opt ), and if f _{k-1 is} not greater than f _k , (X ₀ + ΔX ₀ , Y ₀ + ΔY ₀ , Z ₀ + ΔZ ₀ ) is assigned (X ^opt , Y ^opt , Z ^opt ).

[0088] In the process of calculating the optimum spatial reception angle, the coordinate of the optimal reception angle (X ^opt , y ^opt , Z ^opt ) is determined by previous perturbations. Since there are no disturbances at the beginning of the calculation of the optimal spatial reception angle, the reception angle of the current diode can initially be assigned to the optimal reception angle, and the optimal reception angle is constantly changing in the next few disturbances.

[0089] According to signal processing technology, principles for calculating similarity are described below.

, где

представляет оператор свертки. Группа V^k-1 (V₁..., V_i,..., V_j,..., V_n) сигналов в предыдущее время перед временем k задается в качестве опорной волны группы V сигналов обнаружения в текущее время k.[0090] The degree of similarity matrix at time k is

where

represents a convolution operator. The group V ^k-1 (V ₁ ..., V _i , ..., V _j , ..., V _n ) of signals in the previous time before the time k is set as the reference wave of the group V of detection signals at the current time k.

, где

представляет единичную ступенчатую функцию, и S_th является заданным пороговым значением.[0091] The predetermined degree of similarity is

where

represents a unit step function, and S _th is a predetermined threshold value.

[0092] In a particular implementation of the principles of the above calculation, S _{th is} often 0.8, and the number of signal transmission channels of the diode array is often 6-10. The calculation process is complex, and in traditional technology there is a special convolution function and a special similarity calculation function that can be directly called in coding programs.

[0093] In practice, if each disturbance is applied only in the one-dimensional direction, the number of adjustments and the number of operations required to perform the adjustment to the optimum reception angle increases significantly, and the speed of finding the optimal reception angle becomes small. As the vehicle moves, the actuator continues to regulate, but cannot remain in a relatively stable state, tends to forcibly affect the effect of signal reception, and the requirements for the operating speed for the microprocessor processor 17 and the response speed for the microelectromechanical system are very high. Therefore, it is practical and uncomplicated to carry out such an implementation in order to apply the value (ΔX ₀ , ΔY ₀ , ΔZ ₀ ) of disturbances in the direction of three-dimensional synthesis and move the actuator by 0.01 mm, respectively, which allows satisfying the adaptive tracking effect.

[0094] In the present invention, photoelectric conversion is achieved by using a GaN-based diode array, the reception angle is increased, and the interference of external ambient light is suppressed. In addition, over-averaging technology is applied to several signals, and a GaN-based diode array is encapsulated in a microelectromechanical structure. On this basis, the microcomputer processor achieves the calculation and control of the optimal spatial angle (X ^opt , Y ^opt , Z ^opt ) of the reception in combination with the method of observing disturbances, which improves the ability to track optical signals. Compared to traditional avalanche photodiodes and silicon photodiodes with a high price and low spectral selectivity, a GaN-based LED has the advantages of low cost and a narrow spectrum band. In short, in solutions, the sensitivity of the optical signals is high, the reception angle is large, and the dynamic tracking ability is strong. The time-varying problem of positions between the transmitting device and the receiving device of two vehicles is solved, in particular, due to optical communication between the vehicles.

Claims (24)

1. Rear collision early warning system based on visible light communication, comprising a positioning module (4), an MCU (3), an optical communication modulation module (2), an LED lamp (1), a photosensitive receiver (5), and HMI system (6), while: the positioning module (4) is configured to receive position information, heading information and orientation information when driving the vehicle in question and transmit it to the MCU (3), and the positioning module (4) is connected to the MCU (3); - MCU (3) is configured to obtain a vehicle driving state, a load state and vehicle type information from a tire of a vehicle in question, calculate a chronological path based on the position information of the vehicle in question, and transmit a chronological path, a driving state vehicle, load status and vehicle type information in the optical communication modulation module (2), and modulation module (2) in optical communication connected to the MCU (3); - the optical modulation module (2) is configured to modulate the chronological path, the vehicle driving state, the load state and the vehicle type information and actuate the LED lamp (1) so that it flashes, and the LED lamp (1) connected to the modulation module (2) in optical communication; the LED lamp (1) is mounted in the head of the vehicle and configured to generate an optical signal (9) containing a chronological trajectory, the driving condition of the vehicle, the load condition and information about the type of vehicle for the vehicle in question, and transmit an optical signal (9); - a photosensitive receiving device (5) is mounted in the rear of the vehicle and is configured to receive an optical signal (9) containing a chronological path, a state of propulsion of the vehicle, a load condition and information about the type of vehicle for a vehicle approaching from behind (8) ), which is transmitted through the LED lamp (1) of a vehicle approaching from behind (8), to regulate and demodulate the received optical signal (9) and before Vat demodulated optical signal to the MCU (3) and a photosensitive receiver (5) is connected to the MCU (3); The MCU (3) is configured to calculate the predicted route of the vehicle in question based on position information, heading information and orientation information when driving the vehicle in question and determine whether or not the vehicle in question is in the same lane with the vehicle approaching from behind means (8), based on the position information and the forecast route of the vehicle in question and on the basis of position information and chronological the trajectory of the vehicle approaching from behind (8), the MCU (3) is additionally configured to, if the vehicle in question is in the same lane with the vehicle approaching from behind (8), calculate the TTC between the vehicle in question and the vehicle approaching from behind ( 8) based on the distance and relative speed between the two vehicles, calculate the maximum deceleration value selected for the vehicle approaching from behind means (8), on the basis of information about the type of vehicle and the load condition of the vehicle approaching from behind (8), and select the threshold TTC based on the maximum deceleration value, the MCU (3) is additionally configured to, if the TTC is less than the threshold value TTC during the delay time period exceeding the preset time threshold value, to output an early warning in the HMI system (6) of the vehicle in question in order to perform an early warning of the driver assmatrivaemogo vehicle and HMI-system (6) is connected to the MCU (3); and at the same time, at least the vehicle approaching from behind (8) is equipped with a system of adaptive headlight lamps. 2. The rear collision early warning system based on communication in the visible light range according to claim 1, wherein the LED lamp (1) is an LED daytime running lamp or an LED head light. 3. A method for early warning of collisions in the rear based on communication in the visible light range, in which the system of early warning of collisions in the rear based on communication in the visible light range according to claim 2, is installed both in the vehicle moving in front (7) and in the approaching rear of the vehicle (8), the method comprising: - stage 1, during which, in the process of propulsion: receive by means of a module (4) for positioning a vehicle approaching from behind (8) information about a position of a vehicle approaching from behind (8), calculate, by the MCU (3) of the rear-approaching vehicle (8), the chronological trajectory of the rear-approaching vehicle (8) based on the position information of the rear-approaching vehicle (8), by means of the MCU (3) of the rear-approaching vehicle (8), the driving state and the load state of the rear-approaching vehicle (8) from the vehicle tire, transmit via the MCU (3) of a vehicle approaching from behind (8) position information, a chronological trajectory, driving state, load condition and vehicle type information of a vehicle approaching from behind of a vehicle (8) to an optical modulation module (2) approaching from behind the vehicle (8), encode, by optical modulation module (2), in optical communication of a vehicle approaching from behind (8), position information, a chronological path, driving state, load condition, and vehicle type information of a vehicle approaching from behind (8) and drive by means of a modulation module (2) in optical communication an LED daytime running lamp or a LED headlight of a vehicle approaching from behind (8) so that it blinks to form an optical signal (9), containing position information, a chronological trajectory, propulsion state, load condition and vehicle type information for a vehicle approaching from behind (8), and transmits optical signal (9); and - stage 2, in which: regulate and demodulate by means of a photosensitive receiving device (5) of a vehicle moving in front (7), when receiving an optical signal (9) transmitted by a vehicle approaching from behind (8), a received optical signal (9), calculating by the MCU (3) of the vehicle ahead of the vehicle (7) the predicted route of the vehicle ahead of the vehicle (7) based on position information, course information and orientation information when driving the vehicle in front of the vehicle (7), determine by means of the MCU (3) of the vehicle ahead of the vehicle (7) whether the vehicle ahead of the vehicle (7) is in the same lane with the vehicle approaching from the rear (8) based on the position information and the predicted route of the vehicle ahead of the vehicle ( 7) and based on information about the position and chronological trajectory of the vehicle approaching from behind (8), calculated by the MCU (3) of the vehicle in front of the vehicle (7), if the vehicle in front of it (7) is in the same lane with the vehicle approaching from the rear (8), the TTC between the vehicle moving in front of (7) and the vehicle approaching from behind a vehicle (8) based on the distance and relative speed between two vehicles, calculating, by the MCU (3) of the vehicle in front of the vehicle (7), the maximum deceleration value selected for the vehicle approaching from behind (8) based on information about the type of vehicle and the load condition of the vehicle approaching from behind (8), select, by the MCU (3) of the vehicle in front of the vehicle (7), the threshold TTC value based on the maximum deceleration value and output via the MCU (3) of the vehicle ahead of the vehicle (7), if the TTC is less than the threshold TTC during the delay time period exceeding the preset time threshold, early warning to the HMI system (6) of the vehicle ahead of the vehicle (7) ) to carry out early warning to the driver of the vehicle moving in front (7), while the vehicle approaching from behind (8) is equipped with a system of adaptive headlights.

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