A wireless street light speed measurement method based on the Internet of Things

Abstract

The present invention discloses a wireless street light speed measurement method based on the Internet of Things, which belongs to the field of communication technology and includes a starting speed measurement node, an intermediate speed measurement node, an end speed measurement node, a 5G mobile base station and a cloud server, which solves the problem that the local time of the speed measurement node is difficult to keep consistent with the time of the server and the speed measurement error is large; the present invention sets the speed measurement node on the street light to form an integrated speed measurement lighting wireless transmission node, and supplements the light source through a second lighting lamp, which solves the problem of insufficient light for shooting at night and improves the shooting effect; after the speed measurement point loses connection, the present invention sends a link instruction to the lost speed measurement point through a neighboring node, which greatly improves the probability of the lost node relinking, saves time, and reduces the load of the cloud server.

Description

Technical Field

[0001] The present invention belongs to the field of communication technology, and in particular relates to a wireless street light speed measurement method based on the Internet of Things. Background Art

[0002] The so-called interval speed measurement is to set up two adjacent monitoring points on the same section of road, calculate the average speed of the vehicle on the section based on the time it takes for the vehicle to pass through the two monitoring points, and determine whether the vehicle is speeding or violating traffic rules based on the speed limit standard on the section.

[0003] Currently, interval speed measurement systems are set up with three speed measurement points, namely, the starting point, the midpoint and the end point, so that the vehicle speed can be calculated more accurately.

[0004] The traditional interval speed measurement system has the following disadvantages:

[0005] 1. It is difficult for the local time of the speed test node to be consistent with the server time, resulting in a large speed test error;

[0006] 2. After the speed measurement node is set, it is easy to have insufficient light for shooting, resulting in poor shooting effect;

[0007] 3. After the speed measurement point loses connection, the cloud server can only repeatedly call the speed measurement point to reconnect, which takes up too much data throughput and processing resources of the cloud server. Summary of the invention

[0008] The purpose of the present invention is to provide a wireless street light speed measurement method based on the Internet of Things, which solves the shortcomings of traditional technology.

[0009] To achieve the above object, the present invention adopts the following technical solutions:

[0010] A wireless street light speed measurement system based on the Internet of Things, characterized in that: it includes a starting speed measurement node, an intermediate speed measurement node, an end speed measurement node, a 5G mobile base station and a cloud server, the starting speed measurement node, the intermediate speed measurement node and the end speed measurement node all communicate with the cloud server through the 5G mobile base station, and the starting speed measurement node, the intermediate speed measurement node and the end speed measurement node also communicate with each other through the 5G mobile base station;

[0011] The starting speed measurement node, the intermediate speed measurement node and the end speed measurement node are all used to capture the license plate image of the vehicle under test and send the license plate image to the cloud server;

[0012] The cloud server verifies the license plate image of the vehicle under test and calculates the speed of the vehicle under test through the interval speed measurement method;

[0013] The starting speed measurement node, the intermediate speed measurement node and the terminal speed measurement node each include a power module, a 5G wireless module, a camera, an image decoder, an FPGA chip, a main lighting driving unit and a second lighting driving unit;

[0014] The 5G wireless module and image decoder are both connected to the FPGA chip;

[0015] The FPGA chip controls the main lighting driving unit and the second lighting driving unit through the IO port;

[0016] The main lighting driving unit includes a high-power LED driving chip IC3, a street lamp wick LED1, a relay J1, a transistor Q12 and a resistor R1, the base of the transistor Q12 is connected to an IO port of the FPGA chip through the resistor R1, the collector is connected to a 12V power supply, the emitter is connected to one end of the coil of the relay J1, and the other end of the coil of the relay J1 is connected to the ground wire;

[0017] The common contact of relay J1 is connected to the VIN power supply, the normally open contact is connected to the positive pole of the street lamp wick LED1, the negative pole of the street lamp wick LED1 is connected to the 7th pin of the high-power LED driver chip IC3, the 1st pin of the high-power LED driver chip IC3 is connected to the ground wire, and the 2nd pin is connected to the ground wire through the resistor R3;

[0018] The second lighting driving unit includes a low-power LED driving chip IC11 and its peripheral circuits, a second lighting lamp LED2, a relay J2, a transistor Q2 and a resistor R4;

[0019] The relay of transistor Q2 is connected to an IO port of the FPGA chip through resistor R4, the relay is connected to a 12V power supply, the emitter is connected to one end of the coil of relay J2, the other end of the coil of relay J2 is connected to the ground wire, the VIN pin of the low-power LED driver chip IC11 is connected to the normally open contact of relay J2, and the common contact of relay J2 is connected to the power supply VIN;

[0020] The power module includes a bridge B1, a capacitor C1, a three-terminal voltage regulator IC1 and its peripheral filter circuit, a three-terminal voltage regulator IC2 and its peripheral filter circuit, and a three-terminal voltage regulator IC14 and its peripheral filter circuit. The input end of the bridge B1 is connected to the AC power supply, one end of the output end outputs the VIN power supply, and the other end outputs the ground line; the capacitor C1 is a filter capacitor for the VIN power supply;

[0021] The input end of the three-terminal voltage regulator IC1 is connected to the VIN power supply, and the output end outputs the 12V power supply. The peripheral filter circuit of the three-terminal voltage regulator IC1 is a capacitor filter network composed of capacitors C3 and C4;

[0022] The input end of the three-terminal voltage regulator IC2 is connected to a 12V power supply, and the output end outputs a 5V power supply. The peripheral filter circuit of the three-terminal voltage regulator IC2 is a capacitor filter network composed of capacitors C5 and C6;

[0023] The input end of the three-terminal voltage regulator IC14 is connected to a 12V power supply, and the output end outputs a 3.3V power supply. The peripheral filter circuit of the three-terminal voltage regulator IC14 is a capacitor filter network composed of capacitors C15 and C16;

[0024] The 5G wireless module is powered by a 5V power supply, and the image decoder and FPGA chip are powered by a 3.3V power supply;

[0025] The camera is powered by a 12V power supply.

[0026] Preferably, the model of the high-power LED driver chip IC3 is SM2082EG; the model of the low-power LED driver chip IC11 is SD42524; the model of the three-terminal regulator IC1 is LM7812; the model of the three-terminal regulator IC2 is LM7805; the model of the image decoder is AL582; and the model of the three-terminal regulator IC14 is LDO1117-3.3V.

[0027] Preferably, the model of the 5G wireless module is NB-IoT / 5G / LTE Internet of Things module M5311, and the 5G wireless module also includes a SIM card slot.

[0028] A wireless street light speed measurement method based on the Internet of Things comprises the following steps:

[0029] Step 1: Establish a wireless street light speed measurement system based on the Internet of Things;

[0030] Step 2: The starting speed measurement node first captures a vehicle under test, and then identifies the license plate of the vehicle under test to generate license plate information;

[0031] Step 3: The starting speed measurement node generates an image data packet, which includes the header, device ID, timestamp, encryption code, license plate number information, last heartbeat timestamp, image data, checksum and end character;

[0032] Step 4: The starting speed measurement node sends an image data packet to the cloud server. After receiving the image data packet, the cloud server generates a speed measurement event and assigns an ID to the speed measurement event.

[0033] Step 5: The cloud server analyzes the image data packet, records and saves the license plate number information and image data;

[0034] Step 6: The cloud server verifies the timestamp and the last heartbeat timestamp to see if they are consistent with the local time of the cloud server: if yes, execute step 7; if not, send a time calibration instruction to the starting speed measurement node, which includes the initial text, device ID, timestamp, encryption code, check code and end character;

[0035] The starting speed measurement node synchronizes the time according to the time calibration instruction and returns a heartbeat instruction, which includes the header, device ID, timestamp, checksum and end character;

[0036] Step 7: The cloud server sends a speed measurement event package to the intermediate speed measurement node and the terminal speed measurement node at the same time; the speed measurement event package includes the header, speed measurement event ID, timestamp, encryption code, license plate number information, check code and end character;

[0037] Step 8: After receiving the speed measurement event packet, the intermediate speed measurement node and the terminal speed measurement node allocate a speed measurement event buffer to store the speed measurement event ID, timestamp and license plate number information;

[0038] Step 9: After the intermediate speed measurement node or the terminal speed measurement node captures the vehicle under test, the license plate of the vehicle under test is analyzed. When the analysis result is consistent with the license plate information, the intermediate speed measurement node or the terminal speed measurement node generates a speed measurement data packet;

[0039] The speed measurement data packet includes the header, device ID, speed measurement event ID, timestamp, encryption code, license plate information, last heartbeat timestamp, image data, checksum and end character;

[0040] Step 10: The intermediate speed measurement node or the terminal speed measurement node sends a speed measurement data packet to the cloud server, which analyzes the speed measurement data packet and performs secondary recognition on the license plate information and image data in the speed measurement data packet: if the license plate information, image data and license plate number information in the image data packet are consistent, then execute step 11; if the license plate information, image data and license plate number information in the image data packet are inconsistent, then generate an error message, and save the license plate number information, image data, license plate information and image data respectively to generate evidence, and execute step 12;

[0041] Step 11: The cloud server obtains the time it takes for the vehicle under test to reach the intermediate speed measurement node or the terminal speed measurement node from the starting speed measurement node by subtracting the timestamp in the speed measurement data packet from the timestamp in the image data packet according to the interval speed measurement method, and calculates the average speed of the vehicle under test based on the passing time of the vehicle under test;

[0042] Step 12: The cloud server records the speed test event and ends.

[0043] Preferably, when executing step 10, if the cloud server finds that the timestamp in the speed measurement data packet is inconsistent with the local time, the cloud server actively sends a time calibration instruction to the intermediate speed measurement node or the end point speed measurement node, and the time calibration principle and method are the same as the method provided in step 6.

[0044] Preferably, when executing step 2, after the starting speed measurement node first captures a vehicle under test, the FPGA chip in the starting speed measurement node controls the transistor Q2 to be turned on through the IO port, thereby turning on the relay J2, causing the low-power LED driver chip IC11 to work, and driving the second lighting lamp LED2 to light up.

[0045] At the same time, the starting speed measurement node generates a speed measurement second lighting lamp instruction packet, and sends the light instruction packet to the intermediate speed measurement node and the terminal speed measurement node. The intermediate speed measurement node and the terminal speed measurement node light up their own second lighting lamps according to the same principle as the starting speed measurement node.

[0046] The wireless street light speed measurement method based on the Internet of Things described in the present invention solves the problem that the local time of the speed measurement node is difficult to keep consistent with the server time, resulting in a large speed measurement error; the present invention sets the speed measurement node on the street light to form an integrated speed measurement lighting wireless transmission node, and uses a second lighting lamp to supplement the light source, thereby solving the problem of insufficient light for shooting at night and improving the shooting effect; after the speed measurement point loses connection, the present invention sends a link instruction to the lost speed measurement point through a neighboring node, thereby greatly improving the probability of the lost node reconnecting, saving time, and reducing the load of the cloud server. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a system architecture diagram of the present invention;

[0048] Figure 2 is a circuit diagram of a speed measurement node of the present invention;

[0049] Figure 3 The circuit diagram of the main lighting driving unit of the present invention is

[0050] Figure 4 is a circuit diagram of a second lighting driving unit of the present invention;

[0051] Figure 5 is a circuit diagram of a 5G wireless module of the present invention;

[0052] Figure 6 is a circuit diagram of a power module of the present invention;

[0053] Figure 7 It is the main flow chart of the present invention;

[0054] Figure 8is a heartbeat processing flow chart of the present invention;

[0055] Fig. 9 It is the installation schematic diagram of the present invention;

[0056] Fig.10 It is a schematic diagram of the application of the present invention;

[0057] In the figure: street light pole 1, street light 2, camera 3, pan-tilt stand 4, support rod 5, shell 6, antenna base 7, antenna 8, second lighting lamp 9. DETAILED DESCRIPTION

[0058] Embodiment 1:

[0059] like Figure 1-Figure 6 A wireless street light speed measurement system based on the Internet of Things is shown, characterized in that it includes a starting speed measurement node, an intermediate speed measurement node, an end speed measurement node, a 5G mobile base station and a cloud server, wherein the starting speed measurement node, the intermediate speed measurement node and the end speed measurement node all communicate with the cloud server through the 5G mobile base station, and the starting speed measurement node, the intermediate speed measurement node and the end speed measurement node also communicate with each other through the 5G mobile base station;

[0060] The starting speed measurement node, the intermediate speed measurement node and the end speed measurement node are all used to capture the license plate image of the vehicle under test and send the license plate image to the cloud server;

[0061] The cloud server verifies the license plate image of the vehicle under test and calculates the speed of the vehicle under test through the interval speed measurement method;

[0062] The starting speed measurement node, the intermediate speed measurement node and the terminal speed measurement node each include a power module, a 5G wireless module, a camera, an image decoder, an FPGA chip, a main lighting driving unit and a second lighting driving unit;

[0063] The 5G wireless module and image decoder are both connected to the FPGA chip;

[0064] The FPGA chip controls the main lighting driving unit and the second lighting driving unit through the IO port;

[0065] The main lighting driving unit includes a high-power LED driving chip IC3, a street lamp wick LED1, a relay J1, a transistor Q12 and a resistor R1, the base of the transistor Q12 is connected to an IO port of the FPGA chip through the resistor R1, the collector is connected to a 12V power supply, the emitter is connected to one end of the coil of the relay J1, and the other end of the coil of the relay J1 is connected to the ground wire;

[0066] The common contact of relay J1 is connected to the VIN power supply, the normally open contact is connected to the positive pole of the street lamp wick LED1, the negative pole of the street lamp wick LED1 is connected to the 7th pin of the high-power LED driver chip IC3, the 1st pin of the high-power LED driver chip IC3 is connected to the ground wire, and the 2nd pin is connected to the ground wire through the resistor R3;

[0067] The second lighting driving unit includes a low-power LED driving chip IC11 and its peripheral circuits, a second lighting lamp LED2, a relay J2, a transistor Q2 and a resistor R4;

[0068] The relay of transistor Q2 is connected to an IO port of the FPGA chip through resistor R4, the relay is connected to a 12V power supply, the emitter is connected to one end of the coil of relay J2, the other end of the coil of relay J2 is connected to the ground wire, the VIN pin of the low-power LED driver chip IC11 is connected to the normally open contact of relay J2, and the common contact of relay J2 is connected to the power supply VIN;

[0069] The power module includes a bridge B1, a capacitor C1, a three-terminal voltage regulator IC1 and its peripheral filter circuit, a three-terminal voltage regulator IC2 and its peripheral filter circuit, and a three-terminal voltage regulator IC14 and its peripheral filter circuit. The input end of the bridge B1 is connected to the AC power supply, one end of the output end outputs the VIN power supply, and the other end outputs the ground line; the capacitor C1 is a filter capacitor for the VIN power supply;

[0070] The input end of the three-terminal voltage regulator IC1 is connected to the VIN power supply, and the output end outputs the 12V power supply. The peripheral filter circuit of the three-terminal voltage regulator IC1 is a capacitor filter network composed of capacitors C3 and C4;

[0071] The input end of the three-terminal voltage regulator IC2 is connected to a 12V power supply, and the output end outputs a 5V power supply. The peripheral filter circuit of the three-terminal voltage regulator IC2 is a capacitor filter network composed of capacitors C5 and C6;

[0072] The input end of the three-terminal voltage regulator IC14 is connected to a 12V power supply, and the output end outputs a 3.3V power supply. The peripheral filter circuit of the three-terminal voltage regulator IC14 is a capacitor filter network composed of capacitors C15 and C16;

[0073] The 5G wireless module is powered by a 5V power supply, and the image decoder and FPGA chip are powered by a 3.3V power supply;

[0074] The camera is powered by a 12V power supply.

[0075] Preferably, the model of the high-power LED driver chip IC3 is SM2082EG; the model of the low-power LED driver chip IC11 is SD42524; the model of the three-terminal regulator IC1 is LM7812; the model of the three-terminal regulator IC2 is LM7805; the model of the image decoder is AL582; and the model of the three-terminal regulator IC14 is LDO1117-3.3V.

[0076] Preferably, the model of the 5G wireless module is NB-IoT / 5G / LTE Internet of Things module M5311, and the 5G wireless module also includes a SIM card slot.

[0077] When in use, the street lamp wick LED1 is the main lighting wick of the street lamp. This embodiment adopts the existing LED street lamp wick and SM2082EG as the driving chip to ensure the main lighting function of the street lamp. This embodiment adopts FPGA chip to remotely control the street lamp.

[0078] The camera of this embodiment adopts an interval speed measurement camera. The interval speed measurement camera is a prior art, so it is not described in detail. The camera sends the captured image to AL582 for image decoding and digital processing, thereby obtaining digital image data. The FPGA chip packages the digital image data and sends it to the cloud server.

[0079] The FPGA chip controls the action of the relay J2 by ​​controlling the conduction of the transistor Q2, thereby turning on the second lighting lamp LED2 to supplement the lighting source. Since the second lighting lamp does not require too high power, this embodiment uses SD42524 as the driver chip, which is simple and convenient to control. The PWM input end of the SD42524 provides a PWM signal for dimming from an IO port of the FPGA.

[0080] This embodiment uses the NB-IoT / 5G / LTE Internet of Things module M5311 as a wireless data transmission module, which operates in the 5G frequency band, greatly increasing the data upload speed.

[0081] like Fig. 9 The figure shows the installation diagram of the present invention. The starting speed measurement node, the intermediate speed measurement node and the terminal speed measurement node are all designed as an integrated street lamp. The power module, the 5G wireless module, the camera, the image decoder, the FPGA chip, the main lighting drive unit and the second lighting drive unit are all arranged on a circuit board. The circuit board is arranged in a shell 6. The outside of the shell 6 is provided with an antenna base 7. The upper side of the antenna base 7 is provided with an antenna 8. The antenna 8 is connected to the 5G wireless module through a wire for transmitting and receiving 5G signals. The shell 6 is fixedly arranged on the street lamp pole 1. The top of the street lamp pole is provided with a street lamp 2. The street lamp 2 is Figure 3In the circuit diagram, the street lamp wick LED1, the main lighting driving unit drives the street lamp 2;

[0082] like Figure 4 and Fig. 9 As shown, Figure 4 The second lighting lamp LED2 in the circuit diagram is Fig. 9 The second lighting lamp 9 is arranged next to the street lamp 2, and the second lighting driving unit drives the second lighting lamp 9. A supporting rod 5 is also arranged on the top of the street lamp pole 1, and a pan-tilt seat 4 is arranged on the supporting rod 5. A camera 3 is arranged on the pan-tilt seat 4, and the camera 3 is electrically connected to the image decoder through a video line.

[0083] like Fig.10 As shown, when in use, the starting speed measurement node, the intermediate speed measurement node and the terminal speed measurement node are arranged at intervals in sequence beside the road according to the direction of vehicle travel. The vehicle's license plate information is collected by camera 3, and then the 5G wireless module sends the license plate information to the 5G mobile base station through the 5G network, and then the 5G mobile base station sends it to the cloud server for processing.

[0084] The present invention combines the speed measurement system with the street lamp, greatly improves the shooting effect by controlling the lighting of the street lamp, increases the accuracy of speed measurement, reduces the requirements for the camera, and reduces the cost.

[0085] Embodiment 2:

[0086] like Figure 7 and Figure 8 The wireless street light speed measurement method based on the Internet of Things described in Example 2 is implemented on the basis of the wireless street light speed measurement system based on the Internet of Things described in Example 1, and includes the following steps:

[0087] Step 1: Establish a wireless street light speed measurement system based on the Internet of Things;

[0088] Step 2: The starting speed measurement node first captures a vehicle under test, and then identifies the license plate of the vehicle under test to generate license plate information;

[0089] Step 3: The starting speed measurement node generates an image data packet, which includes the header, device ID, timestamp, encryption code, license plate number information, last heartbeat timestamp, image data, checksum and end character;

[0090] Step 4: The starting speed measurement node sends an image data packet to the cloud server. After receiving the image data packet, the cloud server generates a speed measurement event and assigns an ID to the speed measurement event.

[0091] Step 5: The cloud server analyzes the image data packet, records and saves the license plate number information and image data;

[0092] Step 6: The cloud server verifies the timestamp and the last heartbeat timestamp to see if they are consistent with the local time of the cloud server: if yes, execute step 7; if not, send a time calibration instruction to the starting speed measurement node, which includes the initial text, device ID, timestamp, encryption code, check code and end character;

[0093] The starting speed measurement node synchronizes the time according to the time calibration instruction and returns a heartbeat instruction, which includes the header, device ID, timestamp, checksum and end character;

[0094] Step 7: The cloud server sends a speed measurement event package to the intermediate speed measurement node and the terminal speed measurement node at the same time; the speed measurement event package includes the header, speed measurement event ID, timestamp, encryption code, license plate number information, check code and end character;

[0095] Step 8: After receiving the speed measurement event packet, the intermediate speed measurement node and the terminal speed measurement node allocate a speed measurement event buffer to store the speed measurement event ID, timestamp and license plate number information;

[0096] Step 9: After the intermediate speed measurement node or the terminal speed measurement node captures the vehicle under test, the license plate of the vehicle under test is analyzed. When the analysis result is consistent with the license plate information, the intermediate speed measurement node or the terminal speed measurement node generates a speed measurement data packet;

[0097] The speed measurement data packet includes the header, device ID, speed measurement event ID, timestamp, encryption code, license plate information, last heartbeat timestamp, image data, checksum and end character;

[0098] Step 10: The intermediate speed measurement node or the terminal speed measurement node sends a speed measurement data packet to the cloud server, which analyzes the speed measurement data packet and performs secondary recognition on the license plate information and image data in the speed measurement data packet: if the license plate information, image data and license plate number information in the image data packet are consistent, then execute step 11; if the license plate information, image data and license plate number information in the image data packet are inconsistent, then generate an error message, and save the license plate number information, image data, license plate information and image data respectively to generate evidence, and execute step 12;

[0099] Step 11: The cloud server obtains the time it takes for the vehicle under test to reach the intermediate speed measurement node or the terminal speed measurement node from the starting speed measurement node by subtracting the timestamp in the speed measurement data packet from the timestamp in the image data packet according to the interval speed measurement method, and calculates the average speed of the vehicle under test based on the passing time of the vehicle under test;

[0100] Step 12: The cloud server records the speed test event and ends.

[0101] Preferably, when executing step 10, if the cloud server finds that the timestamp in the speed measurement data packet is inconsistent with the local time, the cloud server actively sends a time calibration instruction to the intermediate speed measurement node or the end point speed measurement node, and the time calibration principle and method are the same as the method provided in step 6.

[0102] Preferably, when executing step 2, after the starting speed measurement node first captures a vehicle under test, the FPGA chip in the starting speed measurement node controls the transistor Q2 to be turned on through the IO port, thereby turning on the relay J2, causing the low-power LED driver chip IC11 to work, and driving the second lighting lamp LED2 to light up.

[0103] At the same time, the starting speed measurement node generates a speed measurement second lighting lamp instruction packet, and sends the light instruction packet to the intermediate speed measurement node and the terminal speed measurement node. The intermediate speed measurement node and the terminal speed measurement node light up their own second lighting lamps according to the same principle as the starting speed measurement node.

[0104] In this embodiment, at each preset time, each speed measurement node sends a heartbeat signal to the cloud server. Each speed measurement node is a starting speed measurement node, an intermediate speed measurement node, and an end speed measurement node. The steps are as follows:

[0105] Step S1: The speed measurement node sends a heartbeat signal to the cloud server at regular intervals;

[0106] Step S2: The cloud server periodically inspects the signal signals of all speed measurement nodes to determine which speed measurement node has not sent a heartbeat signal, that is, the cloud server determines whether a heartbeat signal has been received: if yes, the speed measurement node is marked as a trusted node; if no, the node is marked as a disconnected node;

[0107] Step S3: The cloud server records the ID of the lost node, and sends a transparent call instruction to the neighboring nodes of the lost node according to the ID of the lost node. The transparent call instruction includes an initial text, a device ID, an encryption code, a timestamp, a transparent heartbeat instruction, a check code and an end character;

[0108] Step S4: The neighboring node forwards the transparent call instruction to the lost node, and returns after judging whether it is true or not: if it is true, the neighboring node sends a resend heartbeat instruction to the lost node, and executes step S5; if it is false, the neighboring node returns a connection failure message to the cloud server, and executes step S6;

[0109] The information returned by the lost node to the neighboring node includes the header, device ID, timestamp, checksum and end character;

[0110] Step S5: The lost node resends a heartbeat command to the cloud server, and the neighboring node sends a return success command to the cloud server;

[0111] After receiving the heartbeat command from the lost node, the cloud server sends a re-time calibration command and the local timestamp of the cloud server to the lost node. After the lost node performs re-time calibration, the cloud server re-marks the lost node as a trusted node.

[0112] If the cloud server still cannot receive the heartbeat instruction of the lost node after receiving the return success instruction, execute step S6;

[0113] Step S6: The cloud server records the loss of connection event and waits for the next heartbeat sending time.

[0114] The present invention continuously calibrates the speed measurement node through the heartbeat mechanism, so that its local time is consistent with the cloud server time, which greatly improves the accuracy of speed measurement.

[0115] The wireless street light speed measurement method based on the Internet of Things described in the present invention solves the problem that the local time of the speed measurement node is difficult to keep consistent with the server time, resulting in a large speed measurement error; the present invention sets the speed measurement node on the street light to form an integrated speed measurement lighting wireless transmission node, and uses a second lighting lamp to supplement the light source, thereby solving the problem of insufficient light for shooting at night and improving the shooting effect; after the speed measurement point loses connection, the present invention sends a link instruction to the lost speed measurement point through a neighboring node, thereby greatly improving the probability of the lost node reconnecting, saving time, and reducing the load of the cloud server.

Claims

1. A wireless street light speed measurement method based on the Internet of Things, characterized in that: The steps include: Step 1: Establish a wireless street light speed measurement method based on the Internet of Things; Step 2: The starting speed measurement node first captures a vehicle under test, and then identifies the license plate of the vehicle under test to generate license plate information; Step 3: The starting speed measurement node generates an image data packet, which includes the header, device ID, timestamp, encryption code, license plate number information, last heartbeat timestamp, image data, checksum and end character; Step 4: The starting speed measurement node sends an image data packet to the cloud server. After receiving the image data packet, the cloud server generates a speed measurement event and assigns an ID to the speed measurement event. Step 5: The cloud server analyzes the image data packet, records and saves the license plate number information and image data; Step 6: The cloud server verifies the timestamp and the last heartbeat timestamp to see if they are consistent with the local time of the cloud server: if yes, proceed to step 7; If not, a time calibration instruction is sent to the starting speed measurement node. The time calibration instruction includes an initial character, a device ID, a timestamp, an encryption code, a check code, and an end character. The starting speed measurement node synchronizes the time according to the time calibration instruction and returns a heartbeat instruction, which includes the header, device ID, timestamp, checksum and end character; Step 7: The cloud server sends a speed measurement event package to the intermediate speed measurement node and the terminal speed measurement node at the same time; the speed measurement event package includes the header, speed measurement event ID, timestamp, encryption code, license plate number information, check code and end character; Step 8: After receiving the speed measurement event packet, the intermediate speed measurement node and the terminal speed measurement node allocate a speed measurement event buffer to store the speed measurement event ID, timestamp and license plate number information; Step 9: After the intermediate speed measurement node or the terminal speed measurement node captures the vehicle under test, the license plate of the vehicle under test is analyzed. When the analysis result is consistent with the license plate information, the intermediate speed measurement node or the terminal speed measurement node generates a speed measurement data packet; The speed measurement data packet includes the header, device ID, speed measurement event ID, timestamp, encryption code, license plate information, last heartbeat timestamp, image data, checksum and end character; Step 10: The intermediate speed measurement node or the terminal speed measurement node sends a speed measurement data packet to the cloud server, which analyzes the speed measurement data packet and performs secondary recognition on the license plate information and image data in the speed measurement data packet: if the license plate information, image data and license plate number information in the image data packet are consistent, then execute step 11; if the license plate information, image data and license plate number information in the image data packet are inconsistent, then generate an error message, and save the license plate number information, image data, license plate information and image data respectively to generate evidence, and execute step 12; Step 11: The cloud server obtains the time it takes for the vehicle under test to reach the intermediate speed measurement node or the terminal speed measurement node from the starting speed measurement node by subtracting the timestamp in the speed measurement data packet from the timestamp in the image data packet according to the interval speed measurement method, and calculates the average speed of the vehicle under test based on the passing time of the vehicle under test; Step 12: The cloud server records the speed test event and ends.

2. The method for measuring speed of wireless street lights based on the Internet of Things as claimed in claim 1, characterized in that: When executing step 10, if the cloud server finds that the timestamp in the speed measurement data packet is inconsistent with the local time, the cloud server actively sends a time calibration instruction to the intermediate speed measurement node or the end point speed measurement node. The time calibration principle and method are the same as those provided in step 6.

3. The method for measuring speed of wireless street lights based on the Internet of Things as claimed in claim 1, characterized in that: When executing step 2, after the starting speed measurement node first captures a vehicle under test, the FPGA chip in the starting speed measurement node controls the transistor Q2 to be turned on through the IO port, thereby turning on the relay J2, so that the low-power LED driver chip IC11 works and drives the second lighting lamp LED2 to light up; At the same time, the starting speed measurement node generates a speed measurement second lighting lamp instruction packet, and sends the light instruction packet to the intermediate speed measurement node and the terminal speed measurement node. The intermediate speed measurement node and the terminal speed measurement node light up their own second lighting lamps according to the same principle as the starting speed measurement node.

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