CN103761882B - A kind of automatic cross crossroads traffic light control device and application - Google Patents

Abstract

The invention discloses an automatic crossroad traffic light control device and its application. The device is composed of an input device—a matrix keyboard module 3 , an output device 4 , a sensing device 1 and a stored program digital computer 2 . It operates corresponding to the program control signal stored in the digital computer to sense the congestion status of the intersection and then control the status of the traffic lights at the intersection. The control program completes the control of the traffic light according to the agreed flow according to the parameters and the data transmitted by the sensor equipment of the system. Beneficial effects of the present invention: the crossroad traffic light device controlled by a stored program digital computer according to the present invention will enable the crossroad to obtain the best smoothness and improve the traffic efficiency of the crossroad when operating in the above-mentioned manner.

Description

An automatic crossroad traffic light control device and its application

technical field

The invention relates to a traffic light control system at a crossroad, in particular to an automatic traffic light control device at a crossroad and its application.

Background technique

With the increase of the number of cars in our country, the traffic flow on the road is increasing day by day, and the pressure on the intersection is increasing day by day. It is becoming more and more important to ensure smooth traffic and traffic safety. Traffic jam at intersection is a typical traffic jam. Often there is a small blockage in the central area of the intersection at the beginning (maybe one of the cars on the intersection does not pass completely), but due to the regular alternation of red and green traffic lights in traditional traffic lights, all cars enter the traffic jam area one after another, eventually forming a serious traffic jam. Traffic jam.

Contents of the invention

The main purpose of the present invention is to provide an automatic crossroad traffic light control device to overcome the inherent defects of traditional crossroad traffic lights. The basic principle of the device is as follows. When a partial blockage occurs at a crossroad, the traffic lights in all directions of the crossroad are all red, and cars coming from all directions are prohibited from entering the crossroad, so that the traffic lights that have been blocked in the crossroad can be prevented. The cars leave on their own, thus avoiding long periods of severe traffic jams. When the traffic jam disappears, the traffic lights in all directions at the intersection can immediately return to normal. In order to achieve the purpose of alleviating serious traffic jams at intersections.

The technical scheme that the present invention solves the problems of the technologies described above is as follows:

1. A kind of automatic intersection traffic light control device is made of input device-matrix keyboard module 3, output device 4, sensing device 1 and stored program digital computer 2.

1) The stored-program digital computer 2 is used to store the parameters required by the system and process information collected by all input devices and sensor devices. It consists of a central processing unit (CPU) 2-1, an electrically erasable read-only Memory (EEPROM) 2-2, random access memory (RAM) 2-3, input and output ports (I/O) 2-4 with five ports I, II, III, IV, V, and flash memory (FLASH) 2 -5 composition, electrically erasable read-only memory (EEPROM) 2-2, random access memory (RAM) 2-3, input and output ports (I/O) 2-4 and flash memory (FLASH) 2-5 respectively The central processing unit (CPU) 2-1 is connected, and the central processing unit (CPU) 2-1 is composed of arithmetic/logic unit (ALU) 2-1-1, control and timing circuit 2-1-3, random access memory (RAM ) 2-1-2, the arithmetic/logic unit (ALU) 2-1-1 is connected to the random access memory (RAM) 2-1-2, and the two are respectively connected to the control and timing circuit 2-1-3.

The output device 4 is used to display the parameters of the entire system and the operating status of the entire system, and is composed of an LCD display module 4-1, red and green indicator lights and a control circuit module 4-2.

The sensing device 1 is used to obtain traffic and blockage status information of the monitored crossroads, and transmit the information to the stored-program digital computer 2 after processing the information. The camera 1-1, the video input and decoding chip 1-2 and the ultrasonic Modules 1-3 are composed.

2) The camera 1-1 of the sensing device 1 is connected to the video input and decoding chip 1-2, and the video input and decoding chip 1-2 is connected to the input port I of the stored program digital computer 2, and the ultrasonic wave of the sensing device 1 Modules 1-3 are connected with the input port II of the stored program digital computer 2; the matrix keyboard module 3 is connected with the input port III of the stored program digital computer 2; the output port IV of the stored program digital computer 2 is connected with the LCD display module 4 of the output device 4 -1 connection, the output port V of the stored program digital computer 2 is connected to the control circuit module 4-2 of the output device 4.

The stored-program digital computer dynamically calculates the image frame difference threshold based on the current external environment brightness collected by the sensor device camera 1-1.

The above-mentioned stored-program digital computer includes a stored-program digital computer. In addition to storing the program for dynamically calculating the image frame difference threshold value and the intersection state judgment program, the stored-program digital computer is also allowed to store a program for further operations.

2. In order to provide reliable traffic light state control and improve the timeliness of the traffic light response as much as possible, the above-mentioned stored-program digital computer performs the following steps:

1) It is necessary to select an appropriate threshold for the image frame difference method. First, after the camera 1-1 samples 100 frames of images, the luminance values of each frame are taken out and accumulated and then averaged. In this way, the average brightness value of the external environment at this time is obtained. Then calculate the frame difference threshold of the current image according to the average brightness value brightness and the early, middle and late reference brightness values TM, TA, TN.

2) Improving the timeliness of traffic light response and avoiding the occurrence of misjudgment. Firstly, the stored program digital computer will read the repeated sampling times N preset by the operator to prevent misjudgment, and then after each intersection traffic state judgment, Subtract 1 from the number of repeated sampling times, and judge whether the value reaches 0. If it reaches 0, exit the current round of judgment directly. If it is not 0, continue to the next judgment. Until some kind of intersection state reaches 3/4N. Then, combined with the vehicle height value obtained by the ultrasonic module to determine whether this state is valid.

3. The application of an automatic crossroad traffic light control device. When a partial blockage occurs at the crossroad, the traffic lights in all directions of the crossroad are all red, and cars coming from all directions are prohibited from entering the crossroad. The cars blocked in the intersection leave on their own, thereby avoiding long-term serious traffic jams. When the traffic jam disappears, the traffic lights in all directions of the intersection can immediately return to normal, so as to achieve the purpose of alleviating the serious traffic jam at the intersection; After the central processing unit (CPU) 2-1 finishes reading the system parameters stored in the electrically erasable read-only memory (EEPROM) 2-2. The system enters the real intersection traffic light control state. At this time, both the camera 1-1 and the ultrasonic module 1-3 are aimed at the overlapping area of the intersection. Consider the following three situations:

1) The road is empty and there is no car passing by. At this time, there is almost no difference between the brightness components of the two frames of images captured by camera 1-1. The brightness components of the two frames of images are accumulated and subtracted using the frame difference algorithm, so The obtained value must be much smaller than the image frame difference threshold, and then the central processing unit (CPU) (2-1) continues to read the distance value measured by the ultrasonic module (1-3), because there is no car on the road at this time. Through, the value measured by the ultrasonic module (1-3) must be the erection height of the ultrasonic module (1-3) relative to the road surface, so at this time, the central processing unit (CPU) (2-1) controls the red and green indicator lights The control circuit module (4-2) performs normal operation, that is, the traffic lights are forced to switch at regular intervals;

2) There are cars passing by on the road, but there is no congestion. At this time, due to the movement of getting off the car at the intersection, there must be a large difference in the brightness components of the two frames of images captured by the camera (1-1). When using the frame difference method The luminance components of the two frames of images are accumulated and then subtracted, and the obtained value must be greater than the image frame difference threshold. In this case, the stored program digital computer (2) directly determines that the traffic flow at the intersection is smooth and no congestion occurs. And can not go to read the ranging value of ultrasonic module (1-3), so this moment, stored program digital computer (2) controls red and green indicator light control circuit module (4-2) to carry out normal operation, promptly interval certain Time traffic lights are forced to switch;

3) There are cars passing by on the road, but congestion occurs at the intersection. At this time, because the cars below the intersection are stationary, there is almost no difference in the brightness components of the two frames of images captured by the camera (1-1). The difference algorithm accumulates and subtracts the brightness components of the two frames of images, and the obtained value must be much smaller than the image frame difference threshold. Then, the stored-program digital computer (2) continues to read the distance measured by the ultrasonic module (1-3) value, because there is congestion at the crossroads at this time, the value measured by the ultrasonic module (1-3) must be the height of the ultrasonic module (1-3) relative to the road surface minus the height of the vehicle, so at this time, store The program digital computer (2) controls the traffic lights and the control module (4-2) to forcibly turn on the red light, and prohibits the cars coming from all directions from entering the intersection, so that the cars that have been blocked in the intersection will leave automatically. After disappearing, the traffic lights in all directions at the intersection can immediately return to normal.

Beneficial effects of the present invention: the crossroad traffic light device controlled by a stored program digital computer according to the present invention will make the crossroad obtain the best fluency when operating in the above-mentioned manner, and improve the traffic efficiency of the crossroad at the same time.

Description of drawings

Fig. 1 is a structural schematic diagram of the present invention.

In the figure, sensor device 1, stored program digital computer 2, matrix keyboard module 3, output device 4, camera 1-1, video input and decoding chip 1-2, ultrasonic module 1-3, LCD display module 4-1, Red and green indicator lights and control circuit module 4-2.

Figure 2 is a schematic diagram of the structure of a stored-program digital computer.

In the figure, stored program digital computer 2, central processing unit (CPU) 2-1, electrically erasable read-only memory (EEPROM) 2-2, random access memory (RAM) 2-3, input and output ports (I/ O) 2-4, flash memory (FLASH) 2-5.

Fig. 3 is a schematic diagram of the structure of the stored-program digital computer central processing unit (CPU) 2-1.

In the figure, arithmetic/logic unit (ALU) 2-1-1, control and timing circuit 2-1-3, random access memory (RAM) 2-1-2.

Fig. 4 is a schematic structural diagram of a preferred embodiment of the present invention.

In the figure, stored program digital computer 2, sensing device 1, camera 1-1, video input and decoding chip 1-2, ultrasonic module 1-3, matrix keyboard module 3, LCD display module 4-1, traffic light control interface 5 , traffic light 6, collected data 7.

Fig. 5 is a flow chart of an overall algorithm control program of the present invention.

Fig. 6 is a flowchart of an adaptive algorithm control program of the present invention.

Fig. 7 is a flow chart of the control program of the effective judging algorithm of traffic jam and smooth flow in the present invention.

detailed description

The present invention will be further described below in conjunction with drawings and implementation.

The present invention is conceived on the basis of a stored-program digital computer control system of a traffic light control device at a crossroad, thereby reducing manual intervention on traffic jams at the crossroad. Of course, the first thing to provide is reliable traffic light status control, and at the same time try to improve the timeliness of traffic light response.

Two tasks are derived from the above requirements. First, it is necessary to select an appropriate threshold for the image frame difference method. Since the light intensity will vary in different time periods, the corresponding threshold will also change accordingly. Therefore, the same image frame difference threshold is not feasible at any time period, and the system must be required to automatically adjust the threshold according to the light intensity of the external environment. Second, in order to improve the timeliness of traffic light response, the system adopts the algorithm of taking the majority of N judgments, which not only avoids the occurrence of misjudgment, but also improves the timeliness of traffic light response.

1. A kind of automatic intersection traffic light control device structure of the present invention is as shown in Figure 1, and automatic crossroad traffic light control device is made of sensing equipment 1, stored program digital computer 2, matrix keyboard module 3, output equipment 4, camera 1-1 , Video input and decoding chip 1-2, ultrasonic module 1-3, LCD display module 4-1, control circuit module 4-2. The camera 1-1 completes the video processing part that transmits the analog video signal collected by the camera to the stored-program digital computer after A/D conversion and decoding, and the module and the stored-program digital computer realize data exchange through the input/output interface I. The ultrasonic module 1-3 is used to determine the distance between the ultrasonic reflection point and the location of the ultrasonic module, and the module realizes data exchange with the stored-program digital computer through the input/output interface II. Stored-program digital computer 2, which provides interfaces for each module to communicate with the central processing unit (CPU), including 5 input/output ports I, II, III, IV, and V. The matrix keyboard module 3 is used to input the operating parameters of the system, and this module realizes data exchange with the stored-program digital computer through the input/output interface III. The output device 4 includes an LCD display module 4-1 for outputting system core parameters, and the module realizes data exchange with the stored program digital computer through the input/output interface IV. Red and green indicator lights and control circuit module 4-2, this module realizes data exchange with the stored-program digital computer through the input/output interface V, and realizes the control of the running state of the intersection.

2. The microcontroller structure of the stored-program digital computer 2 is shown in Figure 2. The microcontroller of the stored-program digital computer 2 consists of a central processing unit (CPU) 2-1, an electrically erasable read-only memory (EEPROM) 2- 2. Composed of random access memory (RAM) 2-3, input and output ports (I/O) 2-4, and flash memory (FLASH) 2-5. Integrated circuit central processing unit (CPU) 2-1. Electrically Erasable Read-Only Memory (EEPROM) 2-2 is the place where the parameters of the entire intersection traffic light control system are stored. Random access memory (RAM) 2-3 is the place where the control program of the entire intersection traffic light control system runs. Input and output ports (I/O) 2-4, including input/output ports I, II, III, IV, V corresponding to FIG. 1, are used to realize the interconnection and connection between the stored program digital computer 2 and external devices in FIG. data exchange. Flash memory (FLASH) 2-5 is used to store the control program of the entire intersection traffic light control system. The central processing unit (CPU) 2-1 connects the above-mentioned components through a data bus and an address bus, and realizes orderly work of each component through a control bus. When it is combined with traffic lights at crossroads, once the operator inputs the parameters of the system to the input port of the stored-program digital computer 2, the application system first stores the data entered by the operator into the electrically erasable read-only memory (EEPROM) 2 -2, then the application system can fully handle all control functions.

3. The structure of the central processing unit (CPU) 2-1 is shown in Figure 3. The central processing unit (CPU) 2-1 includes an arithmetic/logic unit (ALU) 2-1-1, a control and timing circuit 2-1- 3. Random Access Memory (RAM) 2-1-2. It consists of an array of storage registers, and this array is well known. Typically, specifically an accumulation register storing one of the operands to be operated on by the Arithmetic/Logic Unit (ALU) 2-1-1, a program counter, an instruction register and decoder and address registers are included in particular.

Arithmetic/logic unit (ALU) 2-1-1 performs arithmetic logic operations on binary data supplied to it. Although not shown, the Arithmetic/Logic Unit (ALU) 2-1-1 also includes an address capable of combining the contents of two registers according to the logic of binary arithmetic. The device allows the processor to perform arithmetic operations on data obtained from the memory. The control and timing circuit 2-1-3 is the main functional unit in the central processing unit (CPU) 2-1, which is used to maintain the correct sequence of the required processing tasks. When the instruction is fetched and decoded, the control circuit initiates the appropriate processing action with the appropriate signal.

4. The structure of the preferred embodiment of the present invention is as shown in Figure 4, which corresponds to the structural schematic diagram of a kind of automatic intersection traffic light control device shown in Figure 1. The functions of the whole system are connected together through the three major buses described in Fig. 2 and Fig. 3, that is, the stored-program digital computer 2 jointly controls the state of the traffic light 6 through a plurality of logical interfaces. The logic interface includes frame difference threshold reading, adaptive threshold adjustment, ultrasonic equipment height value reading, cycle judgment number reading, traffic jam/smooth effective judgment. All these logic interfaces take the data input by the operator or the data 7 collected by the camera 1-1 and the ultrasonic module 1-3 as input, and after a series of logical operations, output the status of the traffic light to the traffic light control interface 5, which is completed by the traffic light control interface 5 The state of the traffic light changes.

5. A flow chart of the overall algorithm control program is shown in Figure 5. The entire program steps are completed by executing a series of related instructions stored in the program-stored digital computer flash memory (FLASH). When the operator turns on the system, the stored program digital computer 2 first initializes each hardware module, including: camera 1-1, ultrasonic module 1-3, LCD display module 4-1, red and green indicator lights and control circuit module 4-2. Then, immediately read the system parameters stored in the stored program digital computer EEPROM (EEPROM) 2-2, including the threshold of the camera frame difference, the number of repeated sampling N of the camera to prevent misjudgment, and the vehicle height range ( cm), these three parameters will be used as the basis for judging the congestion status of the intersection, and a suitable parameter is very important for the entire intersection traffic light control system. Since the intensity of external light changes with time, this will inevitably affect the accuracy of our use of the frame difference method to judge road congestion. Therefore, a fixed frame difference threshold cannot guarantee the reliability of the system. Instead, this threshold must automatically adjust as the external light changes. Of course, all system parameters can be set manually by the operator. At any time when the system is running, the operator can set each system parameter in turn through the input device (matrix keyboard module 3) of the system. The system parameters are immediately saved to the electrically erasable read-only memory (EEPROM) 2-2 of the stored-program digital computer. After the system parameters are ready, the stored-program digital computer 2 starts to obtain intersection information from the camera 1-1 and the ultrasonic module 1-3, and performs a series of logical operations with the information and the system parameters (specifically, effectively judging traffic jams and smooth traffic). The flow chart of the algorithmic control program is given in Fig. 7). The result of the logical operation is the state that the traffic lights at the intersection should maintain. The stored-program digital computer performs corresponding state switching for controlling traffic lights.

6. An adaptive algorithm control program flow of the present invention is shown in FIG. 6 . First, after the camera 1-1 samples 100 frames, the brightness values of each frame are taken out and accumulated and then averaged. In this way, the average brightness value of the external environment at this time is obtained, and then immediately judge whether the brightness value is within a desirable range, and the brightness value must be between the system parameters we set TN (brightness value at night) brightness value). Then determine TVAL (frame difference threshold), the algorithm is as follows: 1) If the average value is between TN (evening brightness value) and TM (morning/afternoon brightness value), the threshold is TVAL=average value/2000; 2 ) If the average value is between TM (morning/afternoon brightness value) and TA (midday brightness value), its threshold is TVAL=average value/1000;

7. The control program flow of the traffic jam and unimpeded effective judgment algorithm of the present invention is as shown in Figure 7. This part of the program will first check whether the number of loop checks reaches 0, if less than 0, continue to judge the traffic jam, unimpeded and effective, and judge After finishing once, the total number of loop judgments will be reduced by 1. All the logic of the algorithm includes the following three situations:

1) The road is empty and there is no car passing by. At this time, there is almost no difference between the brightness components of the two frames of images captured by camera 1-1. The brightness components of the two frames of images are accumulated and subtracted using the frame difference algorithm, so The obtained value must be much smaller than the image frame difference threshold. Then, the stored program digital computer 2 continues to read the distance value measured by the ultrasonic module 1-3, because there is no any car passing by on the road at this moment, the value measured by the ultrasonic module 1-3 must be the distance value measured by the ultrasonic module 1-3. The erection height of the pavement. Therefore, at this time, the program-stored digital computer 2 controls the traffic light module to operate normally, that is, the traffic light is forcibly switched at regular intervals.

2) There are cars passing by on the road, but there is no congestion. At this time, due to the movement of getting off the car at the intersection, there must be a large difference in the brightness components of the two frames of images captured by the camera 1-1. The brightness components of the frame images are accumulated and then subtracted, and the obtained value must be greater than the image frame difference threshold. In this case, the stored-program digital computer 2 directly determines that the traffic flow at the intersection is smooth and no congestion occurs, and does not read the distance measurement values of the ultrasonic modules 1-3. Therefore, at this time, the program-stored digital computer 2 controls the traffic light module to operate normally, that is, the traffic light is forced to switch at regular intervals.

3) There are cars passing by on the road, but congestion occurs at the intersection. At this time, because the cars below the intersection are stationary, there is almost no difference in the brightness components of the two frames of images captured by camera 1-1. When using the frame difference algorithm The luminance components of the two frames of images are accumulated and then subtracted, and the obtained value must be much smaller than the image frame difference threshold. Then, the stored program digital computer 2 continues to read the distance value measured by the ultrasonic module 1-3, because at this moment there is congestion at the intersection, the value measured by the ultrasonic module 1-3 must be the distance that the ultrasonic module is erected relative to the road surface Altitude minus the height of the vehicle. Therefore, at this time, the program-stored digital computer 2 controls the traffic light module to forcibly turn on the red light, prohibiting cars coming from all directions from entering the intersection, so that the cars that have been blocked in the intersection can leave voluntarily. When the traffic jam disappears, the traffic lights in all directions at the intersection can immediately return to normal.

The determination of the final state of the traffic light adopts the algorithm of taking the majority of N judgments, which not only avoids the occurrence of misjudgment, but also improves the timeliness of the traffic light response.

Claims (2)

1. an automatic intersection traffic light control device, it is characterized in that, device is made of input equipment-matrix keyboard module (3), output equipment (4), sensing equipment (1) and stored program digital computer (2), The stored program digital computer (2) is used to store the parameters required by the device, and process the information collected by all input devices and sensing devices, and it consists of a central processing unit (CPU) (2-1), electrically erasable Read-only memory (EEPROM) (2-2), random access memory (RAM) (2-3), input and output ports (I/O) with five ports I, II, III, IV, V (2- 4) Composed of flash memory (FLASH) (2-5), electrically erasable read-only memory (EEPROM) (2-2), random access memory (RAM) (2-3), input and output ports (I/O ) (2-4) and flash memory (FLASH) (2-5) are respectively connected with central processing unit (CPU) (2-1), and central processing unit (CPU) (2-1) is composed of arithmetic/logic unit (ALU) (2-1-1), control and timing circuit (2-1-3), random access memory (RAM) (2-1-2), arithmetic/logic unit (ALU) (2-1-1) After being connected with random storage memory (RAM) (2-1-2), the two are respectively connected with control and timing circuit (2-1-3); The output device (4) is used to display the whole system parameters and the running state of the whole system, and is composed of an LCD display module (4-1), red and green indicator lights and a control circuit module (4-2); The sensing device (1) is used to acquire the status information of the monitored intersection, and after processing the information, transmit it to the stored-program digital computer (2), and the camera (1-1), video input and decoding chip ( 1-2) and an ultrasonic module (1-3); The camera (1-1) of the sensing device (1) is connected with the video input and decoding chip (1-2), and the input port 1 of the video input and decoding chip (1-2) and the stored program digital computer (2) Connecting, the ultrasonic module (1-3) of the sensing device (1) is connected with the input port II of the stored program digital computer (2); the matrix keyboard module (3) is connected with the input port III of the stored program digital computer (2); The output port IV of the stored-program digital computer (2) is connected to the LCD display module (4-1) of the output device (4), and the output port V of the stored-program digital computer (2) is connected to the red and green indicator lights of the output device (4) Connect with the control circuit module (4-2); The described automatic intersection traffic light control device is characterized in that the stored program digital computer dynamically calculates the image frame difference threshold based on the current external environment brightness collected by the sensor device camera (1-1); In order to provide reliable traffic light status control and improve the timeliness of the traffic light response as much as possible, the stored-program digital computer (2) performs the following steps, 1) It is necessary to select an appropriate threshold for the image frame difference method. First, after the camera (1-1) samples 100 frames of images, the brightness values of each frame are taken out and accumulated and averaged, thus obtaining the average value of the external environment at this time. Brightness value brightness, and then calculate the current image frame difference threshold according to the average brightness value brightness and the early, middle and late reference brightness values TM, TA, TN; 2) Improving the timeliness of traffic light response and avoiding the occurrence of misjudgment. Firstly, the stored program digital computer (2) will read the repeated sampling times N preset by the operator to prevent misjudgment, and then carry out each crossroad traffic status After the judgment, subtract 1 from the number of repeated sampling times, and judge whether it reaches 0. If it reaches 0, exit the current round of judgment directly. If it is not 0, continue to make the next judgment until a certain intersection state reaches 3/ 4N, then, combined with the vehicle height value obtained by the ultrasonic module (1-3) to determine whether this state is valid. 2. the application of a kind of automatic crossroad traffic light control device as claimed in claim 1, is characterized in that, when local blockage takes place in crossroad, the traffic lights of each direction of this crossroad all bright red light, forbid each direction When the coming cars enter the intersection, the cars that have been blocked in the intersection can be left by themselves, thereby avoiding long-term serious traffic jams. When the traffic jam disappears, the traffic lights in all directions of the intersection can immediately return to normal. In order to achieve the purpose of alleviating the serious traffic jam at the intersection; In the traffic light control state of the intersection, at this time, the camera (1-1) and the ultrasonic module (1-3) are aimed at the overlapping area of the intersection, consider the following three situations: 1) The road is empty and there is no car passing by. At this time, there is almost no difference between the brightness components of the two frames of images captured by the camera 1-1. After using the frame difference algorithm to accumulate the brightness components of the two frames of images and subtract them, the The obtained value must be far less than the image frame difference threshold, then, the central processing unit CPU (2-1) continues to read the distance value measured by the ultrasonic module (1-3), because there is no any car passing on the road at this moment, The value measured by the ultrasonic module (1-3) must be the erection height of the ultrasonic module (1-3) relative to the road surface, so at this time, the central processing unit CPU (2-1) controls the traffic lights and the control circuit module (4-2) Carry out normal operation, that is, the traffic lights are forced to switch at regular intervals; 2) There are cars passing by on the road, but there is no congestion. At this time, due to the movement of getting off the car at the intersection, there must be a large difference in the brightness components of the two frames of images captured by the camera (1-1). When using the frame difference method The luminance components of the two frames of images are accumulated and then subtracted, and the obtained value must be greater than the image frame difference threshold. In this case, the stored program digital computer (2) directly determines that the traffic flow at the intersection is smooth and no congestion occurs. And can not go to read the ranging value of ultrasonic module (1-3), so this moment, stored program digital computer (2) controls red and green indicator light control circuit module (4-2) to carry out normal operation, promptly interval certain Time traffic lights are forced to switch; 3) There are cars passing by on the road, but congestion occurs at the intersection. At this time, because the cars below the intersection are stationary, there is almost no difference in the brightness components of the two frames of images captured by the camera (1-1). The difference algorithm accumulates and subtracts the brightness components of the two frames of images, and the obtained value must be much smaller than the image frame difference threshold. Then, the stored-program digital computer (2) continues to read the distance measured by the ultrasonic module (1-3) value, because there is congestion at the crossroads at this time, the value measured by the ultrasonic module (1-3) must be the height of the ultrasonic module (1-3) relative to the road surface minus the height of the vehicle, so at this time, store The program digital computer (2) controls the traffic lights and the control module (4-2) to forcibly turn on the red light, and prohibits the cars coming from all directions from entering the intersection, so that the cars that have been blocked in the intersection will leave automatically. After disappearing, the traffic lights in all directions at the intersection can immediately return to normal.