A cable-free seismograph anti-lost search system based on UWB and ultrasound

Abstract

The present invention is applicable to the technical field of cableless seismographs, and provides a cableless seismograph anti-loss search system based on UWB and ultrasound, including: a seismograph node module, a base station module and a PC host computer module. The present invention utilizes the positioning technology combining UWB and ultrasound, utilizes the TOA-based TWR algorithm for UWB ranging, utilizes the TDOA algorithm for ultrasonic ranging, combines the three-sided positioning theory with the least square method for solution, and improves the positioning accuracy of the cableless seismograph; enables the seismograph positioning system to have double protection, and improves the applicability of the cableless seismograph in complex environments; can realize positioning data transmission, ensure the reliability of data transmission, reduce equipment power consumption, greatly reduce the difficulty of base station erection, reduce the economic cost of positioning, and ensure the reliable operation of the equipment.

Description

Technical Field

[0001] The invention belongs to the technical field of cable-free seismographs, and in particular relates to an anti-lost search system for cable-free seismographs based on UWB and ultrasonic waves. Background Art

[0002] The development of seismographs has gone through three major stages: analog seismographs, centralized seismographs, and modern distributed telemetry seismographs. Modern distributed telemetry seismographs currently exist mainly in the form of cableless seismographs. Cableless seismograph acquisition stations are light and easy to carry, suitable for areas with complex ground conditions such as forests, swamps, and deserts. They can easily collect seismic data under complex geological conditions and are the future development direction of seismographs. Cableless seismographs are important equipment for recording, storing, and transmitting seismic data. They have the advantages of "long-term recording, centralized recovery" and flexible laying, but it is precisely these advantages that bring cableless seismographs the disadvantages of being easily lost and easily forgotten. Due to certain human or natural factors, the staff may lose the equipment during centralized recovery, which will lead to the loss of important data resources and hinder subsequent research work. Taking all the above factors into consideration, from a technical perspective, cableless seismographs require a system that allows staff to search and locate comprehensively, so that staff can retrieve lost equipment.

[0003] At present, ultrasonic positioning technology is based on ultrasonic ranging technology. According to different ultrasonic ranging technologies, ultrasonic ranging technology is divided into reflection ranging and one-way ranging according to the installation method of ultrasonic sensors. According to the principle of ultrasonic ranging, it is divided into time of arrival (TOA) method, time difference of arrival (TDOA) method and phase method, etc., and ultrasonic positioning has high accuracy and can achieve accurate measurement at close range. In addition, compared with other positioning technologies, ultra-wideband technology (UWB) uses nanosecond narrow pulses to transmit information, which has the advantages of fast transmission rate, strong penetration, low power consumption, strong anti-interference performance, and wide positioning coverage. Therefore, the joint positioning of UWB and ultrasonic wireless positioning technology can realize the accurate search of cable-free seismographs. Summary of the invention

[0004] The purpose of the embodiments of the present invention is to provide a cable-free seismograph anti-loss search system based on UWB and ultrasound, aiming to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A cable-free seismograph anti-lost search system based on UWB and ultrasonic wave, comprising:

[0007] A seismograph node module, the seismograph node module is used to send location information data of the cable-free seismograph;

[0008] A base station module, the base station module includes a UWB detection unit, an ultrasonic receiving unit, a temperature measuring unit and a Zigbee communication unit; the temperature measuring unit is used to measure the temperature of the surrounding environment; the UWB detection unit and the ultrasonic receiving unit are used to receive the location information data of the seismograph node, and the UWB detection unit and the ultrasonic receiving unit respectively calculate the distance between the seismograph node and the base station using the TOA-based TWR algorithm and the TDOA algorithm; the Zigbee wireless communication unit is used for wireless networking between base stations, and is also used to realize time synchronization between base stations and data transmission between the base station and the data processing unit;

[0009] The PC host computer module is used to further analyze and process the data collected by the base station.

[0010] Furthermore, the seismograph node module includes a UWB tag unit, a temperature measurement unit and an ultrasonic transmitting unit.

[0011] Furthermore, the specific steps of the TWR algorithm are:

[0012] Step 1: The beacon sends a signal to a single base station and records the time of sending the signal as τ AT1x ;

[0013] Step 2: After the base station receives the signal, the time of receiving the signal is recorded as τ BR1x , then the base station delays for a fixed time t replyB , send a signal to the beacon and record the time τ of sending the signal BT1x ;

[0014] Step 3: After the beacon receives the signal, record the time τ of receiving the signal AR1x , followed by a beacon delay of fixed time t replyA , send a signal to the base station and record the sending time τ AT2x ;

[0015] Step 4: The base station receives the signal and records the time τ at which the signal is received BR2x , at this time, a two-way ranging is completed, and the distance between the beacon and the base station is calculated from the measured time:

[0016] By roundA =2×T tof +t replyB , t roundB =2×T tof +t replyA It turns out that:

[0017]

[0018] According to the flight time T of the UWB signal between the seismograph node and the base station tof , calculate the distance between the seismograph node and a single base station, that is, d1 = c × T tof , where c≈3×10 8 m / s.

[0019] Furthermore, the specific steps of the TDOA algorithm are:

[0020] Step 1: The seismograph node sends a time synchronization signal to Zigbee base station No. 1, Zigbee base station No. 2, and Zigbee base station No. 3 at the same time, and transmits an ultrasonic signal at the same time. The seismograph node reads the temperature T1 detected by the temperature sensor;

[0021] Step 2: Zigbee base station No. 1, Zigbee base station No. 2, and Zigbee base station No. 3 start the timer after receiving the time synchronization signal;

[0022] Step 3: After receiving the ultrasonic signal, the timer of Zigbee base station No. 1, No. 2, and No. 3 stops timing, and then reads the temperature detected by the temperature sensor. According to the formula v of the influence of temperature on the speed of sound 声 =331.4+0.0607T, calculate the speed of sound at this time, from s=t×v 声 , calculate the distance s between each base station and the seismograph node, where t is the time recorded by the timer, and calculate the distances s1, s2, and s3 between Zigbee base station No. 1, Zigbee base station No. 2, and Zigbee base station No. 3 and the seismograph node in turn.

[0023] Furthermore, the Zigbee network is a star network topology, the Zigbee network includes a coordinator node and several terminal nodes, the terminal node is connected to the base station module, the terminal node is located at the edge of the Zigbee network, and the coordinator node is connected to the PC host computer module.

[0024] Furthermore, the specific steps of the Zigbee networking process are:

[0025] Step 1: The coordinator node and the terminal node initialize the hardware peripherals and the Zigbee protocol. The terminal node sends an active request to join the Zigbee network message. The routing node assigns a unique address to the terminal. The child node address is assigned by the parent node according to the following formula:

[0026]

[0027] Among them, Cskip is the number of child nodes owned by node m; C m is the number of nodes controlled by node m; L m is the maximum network depth; d is the relative depth from node m to the routing node; R m is the number of nodes used for routing functions;

[0028] When C skip = 0, the node is a child node; when C skip >0, the node is the parent node; the address A of routing node n n For: A n =A parent +C skip (n-1)+1, where A parent is the address of the parent node of node n; the address of the child node l is A l For: A l =A parent +C skip R m +n, where A parent is the address of the parent node of node l;

[0029] Step 2: The coordinator node searches for channels and establishes a network, adds nodes to the network, and runs Zigbee protocol tasks;

[0030] Step 3: The coordinator node loops to determine whether there is wireless information; the terminal node sends T after the ranging is completed. tof information;

[0031] Step 4: The coordinator node receives the wireless data and uploads it to the PC host computer. After the transmission is completed, the next data receiving task begins.

[0032] Furthermore, the PC host module further processes the data collected by the base station using the least square method and the three-sided positioning algorithm. The specific steps of the algorithm are:

[0033] Step 1: Take the geometric center point of the equilateral triangle formed by Zigbee base station No. 1, Zigbee base station No. 2, and Zigbee base station No. 3 as the coordinate origin, the extension line of the line connecting the geometric center point and base station 1 as the positive direction of the y-axis, and the positive direction of the x-axis rotated 90 degrees clockwise around the geometric center point to establish a rectangular coordinate system;

[0034] Step 2: Let the distances of Zigbee base station 1, Zigbee base station 2, and Zigbee base station 3 relative to the origin of the coordinate system be (x1, y1), (x2, y2), and (x3, y3), and let the coordinates of the seismograph node be (x, y). The three-side positioning algorithm gives:

[0035] s12 =(x-x1) 2 +(y-y1) 2 ;

[0036] s2 2 =(x-x2) 2 +(y-y2) 2 ;

[0037] s3 2 =(x-x3) 2 +(y-y3) 2 ;

[0038] Where: s1, s2, s3 are the distances from the projection points of Zigbee base station No. 1, Zigbee base station No. 2, and Zigbee base station No. 3 on the ground to the seismograph node respectively;

[0039] Step 3: Assume that the distance between the measured aerial positioning base point and the ground mobile node is L i (i=1,2,3), assuming the height of the known aerial positioning base point is H, then Solving the equation using the least squares method yields:

[0040]

[0041]

[0042] Among them, (x, y) is the coordinate of the seismograph node in the defined two-dimensional coordinate system.

[0043] Furthermore, the specific steps of wirelessly locating the seismograph node using UWB and ultrasound are as follows:

[0044] Step 1: Based on the placement of the base station in the positioning system, a two-dimensional plane coordinate system is established to obtain the base station coordinate information;

[0045] Step 2: Use UWB and ultrasound to measure the distance between the seismograph node and each base station;

[0046] Step 3: After preliminary screening, the effective distance information obtained by the base station is summarized to the PC host computer through Zigbee wireless communication;

[0047] Step 4: The PC host computer uses the trilateral positioning theory and the least squares method to solve the position information. After obtaining the position information of the cable-free seismograph, the PC host computer is used for human-computer interaction to navigate to the place where the seismograph is lost.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] The cable-free seismograph anti-loss search system based on UWB and ultrasound uses the joint positioning technology combining UWB and ultrasound, uses the TOA-based TWR algorithm for UWB ranging, uses the TDOA algorithm for ultrasonic ranging, combines the three-sided positioning theory with the least squares method for solution, and improves the positioning accuracy of the cable-free seismograph; through the use of UWB and ultrasonic dual positioning technology, the seismograph positioning system has double protection, which can improve the applicability of the cable-free seismograph in complex environments; Zigbee wireless communication units are used for wireless networking to realize positioning data transmission, ensure the reliability of data transmission, reduce equipment power consumption, greatly reduce the difficulty of base station installation, reduce the economic cost of positioning, and ensure the reliable operation of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 Schematic diagram of the cable-free seismograph anti-loss search system.

[0051] Figure 2 This is the schematic diagram of the Zigbee radio frequency communication unit circuit.

[0052] Figure 3 This is the schematic diagram of the UWB radio frequency unit circuit.

[0053] Figure 4 Schematic diagram of TWR ranging algorithm.

[0054] Figure 5 This is the schematic diagram of the ultrasonic transmitting unit circuit.

[0055] Figure 6 This is the circuit schematic diagram of the ultrasonic receiving unit.

[0056] Figure 7 This is the circuit schematic diagram of the temperature measurement unit.

[0057] Figure 8 This is a schematic diagram of the ultrasonic ranging principle.

[0058] Fig. 9 This is a schematic diagram of the three-side positioning principle.

[0059] Fig.10 Coordinate map for wireless positioning of seismograph nodes.

[0060] Fig.11 Flowchart for wireless positioning of seismograph nodes using UWB and ultrasound. DETAILED DESCRIPTION

[0061] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0062] The specific implementation of the present invention is described in detail below in conjunction with specific embodiments.

[0063] An embodiment of the present invention provides a cable-free seismic instrument anti-loss search system based on UWB and ultrasound, comprising:

[0064] A seismograph node module, the seismograph node module is used to send location information data of the cable-free seismograph;

[0065] A base station module, the base station module includes a UWB detection unit, an ultrasonic receiving unit, a temperature measuring unit and a Zigbee communication unit; the temperature measuring unit is used to measure the temperature of the surrounding environment; the UWB detection unit and the ultrasonic receiving unit are used to receive the location information data of the seismograph node, and the UWB detection unit and the ultrasonic receiving unit respectively calculate the distance between the seismograph node and the base station using the TOA-based TWR algorithm and the TDOA algorithm; the Zigbee wireless communication unit is used for wireless networking between base stations, and is also used to realize time synchronization between base stations and data transmission between the base station and the data processing unit;

[0066] The PC host computer module is used to further analyze and process the data collected by the base station.

[0067] In the embodiment of the present invention, preferably, the temperature measurement unit is located on the seismograph node and the base station; the seismograph node and the base station both use STM32F103ZET6 as the main controller, and the Zigbee wireless communication unit uses the chip CC2530, and uses the rubber stick antenna for communication. The application of CC2530 is relatively simple, and only a few external circuits are required to implement it, such as Figure 2 The figure shows the circuit schematic of CC2530. In the wireless communication node, since the RF part of the CC2530 external circuit uses an unbalanced antenna, a balun circuit is built with separate capacitors and separate inductors for optimization. The two ranging methods of UWB and ultrasonic can complement each other, so that the cable-free seismograph can obtain more accurate positioning results in complex working environments.

[0068] As a preferred embodiment of the present invention, the seismograph node module includes a UWB tag unit, a temperature measurement unit and an ultrasonic transmission unit.

[0069] In the embodiment of the present invention, preferably, the seismograph node module also includes a power supply unit and a main control circuit. The UWB tag unit and the UWB detection unit adopt the DWM1000 module, and the DW1000 chip carried therein can transmit and receive UWB pulse signals. The signal power meets the power limit stipulated by the FCC, and can realize two-way ranging between the cable-free seismograph and the base station. The ranging error is as low as the centimeter level, and the maximum transmission distance is 450 meters. It also has the advantages of low power consumption, low cost, small size, and easy integration. It is the preferred ultra-wideband chip for building a UWB real-time positioning system. The unit circuit schematic diagram is shown as follows: Figure 3 As shown; the ultrasonic receiving and transmitting unit uses an ultrasonic transmitter and an ultrasonic probe to realize ultrasonic ranging between a cableless seismograph and a base station. The frequency of the ultrasonic wave is an important parameter in the ultrasonic ranging system. It determines the detectable distance and beam angle of the ultrasonic wave to a certain extent. The higher the frequency, the longer the detectable distance and the smaller the beam angle. The positioning system requires a longer detectable distance and a larger beam angle. After testing, 40kHz ultrasonic waves meet the requirements of this system in terms of detectable distance and beam angle. Therefore, this system selects 40kHz ultrasonic waves for ranging. The ultrasonic transmitting unit uses the stable clock of the STM32 main controller to easily generate a 40kHz square wave pulse signal. After level conversion using the MAX3232 chip, the ultrasonic transmitter can convert the 40kHz square wave signal into an ultrasonic signal and transmit it. The unit circuit schematic diagram is shown as follows Figure 5 As shown; the ultrasonic receiving unit uses the CX20106A chip, and the circuit schematic diagram of ultrasonic receiving processing is as follows Figure 6 As shown. When CX20106A receives a 40kHz signal, it generates a low-level falling pulse at pin 7. This signal can be connected to the external interrupt pin of the main controller as an interrupt signal input. In addition, the Zigbee RF communication between the seismograph node and the base station can achieve the timing synchronization of ultrasonic ranging, thereby obtaining the distance obtained by ultrasonic ranging; the position of the UWB tag unit and the ultrasonic transmitting unit is unknown, and they are placed together with the seismograph node, and transmit and receive UWB signals and ultrasonic signals with each base station to measure the distance between the two.

[0070] As a preferred embodiment of the present invention, the specific steps of the TWR algorithm are:

[0071] Step 1: The beacon sends a signal to a single base station and records the time of sending the signal as τ AT1x ;

[0072] Step 2: After the base station receives the signal, the time of receiving the signal is recorded as τ BR1x , then the base station delays for a fixed time t replyB , send a signal to the beacon and record the time τ of sending the signal BT1x ;

[0073] Step 3: After the beacon receives the signal, record the time τ of receiving the signal AR1x , followed by a beacon delay of fixed time t replyA , send a signal to the base station and record the sending time τ AT2x ;

[0074] Step 4: The base station receives the signal and records the time τ at which the signal is received BR2x , at this time, a two-way ranging is completed, and the distance between the beacon and the base station is calculated from the measured time:

[0075] By roundA =2×T tof +t replyB , t roundB =2×T tof +t replyA It turns out that:

[0076]

[0077] According to the flight time T of the UWB signal between the seismograph node and the base station tof , calculate the distance between the seismograph node and a single base station, that is, d1 = c × T tof , where c≈3×10 8 m / s.

[0078] In the embodiment of the present invention, preferably, the distance between the UWB tag and each base station is calculated using a TOA-based TWR algorithm; the UWB ranging principle is as follows: Figure 4 As shown, the distance between the beacon and the base station is calculated using the TWR algorithm based on the arrival time of the UWB signal.

[0079] As a preferred embodiment of the present invention, the specific steps of the TDOA algorithm are:

[0080] Step 1: The seismograph node sends a time synchronization signal to Zigbee base station No. 1, Zigbee base station No. 2, and Zigbee base station No. 3 at the same time, and transmits an ultrasonic signal at the same time. The seismograph node reads the temperature T1 detected by the temperature sensor;

[0081] Step 2: Zigbee base station No. 1, Zigbee base station No. 2, and Zigbee base station No. 3 start the timer after receiving the time synchronization signal;

[0082] Step 3: After receiving the ultrasonic signal, the timer of Zigbee base station No. 1, No. 2, and No. 3 stops timing, and then reads the temperature detected by the temperature sensor. According to the formula v of the influence of temperature on the speed of sound 声=331.4+0.0607T, calculate the speed of sound at this time, from s=t×v 声 , calculate the distance s between each base station and the seismograph node, where t is the time recorded by the timer, and calculate the distances s1, s2, and s3 between Zigbee base station No. 1, Zigbee base station No. 2, and Zigbee base station No. 3 and the seismograph node in turn.

[0083] In the embodiment of the present invention, preferably, the distance between the ultrasonic beacon and each base station is calculated using the TDOA algorithm, specifically: The ultrasonic ranging principle is as follows: Figure 8 As shown, let the propagation speed of ultrasound in air be v 声 , the Zigbee radio frequency unit transmits electromagnetic waves at the speed of light c. At a certain moment, the transmitting unit simultaneously transmits ultrasonic signals and radio frequency signals, both of which are received by the receiving unit after a distance of S. The propagation time of the ultrasonic wave is t 声 , the propagation time of the RF signal is t 电 The receiving unit starts timing when it receives the RF signal and stops timing when it receives the ultrasonic signal. The timing time is Δt, and t 声 ·v 声 =t 电 c, Δt = t 声 -t 电 ; Due to the large difference between the speed of light and the speed of sound, compared to t 声 , t 电 can be completely ignored, at this time Δt=t 声 , where Δt can be measured by the main controller; hot and cold changes have a great influence on the speed of sound. In the positioning process, the problems caused by temperature need to be taken into account to compensate for the speed of sound. Therefore, the temperature needs to be accurately measured and then the speed of sound is compensated. The temperature measurement unit on the positioning base station and the seismograph node is used to measure the temperature of the surrounding environment, and the temperature is used to compensate the speed of sound, making the distance calculation more accurate. Since there is a certain temperature difference around the moving target and the positioning base point, the temperature of the moving target and the positioning base point are measured. Finally, the speed of sound is corrected by the average temperature between the moving target and the positioning base point, so that the distance between the moving target and the positioning base point can be calculated more accurately. The system uses a digital temperature sensor DS18B20 for temperature acquisition and temperature compensation. The unique single bus structure requires only one wire connection between the DS18B20 and the controller. It has a simple structure and can be used without any peripheral components. The maximum measurement resolution can reach 0.0626 degrees Celsius. The actual measured temperature range is from -55 degrees Celsius to 125 degrees Celsius. It has a simple structure and a small size, and can meet the temperature measurement requirements in most environments. The temperature measurement unit circuit schematic diagram is shown in the figure below. Figure 7 As shown, the actual sound speed can be calculated by combining the effect of temperature on ultrasonic velocity: v声 =331.4+0.0607T, and finally d2=t 声 ×v 声 Solve for the distance between the seismograph node and a single base station.

[0084] As a preferred embodiment of the present invention, the Zigbee network is a star network topology, the Zigbee network includes a coordinator node and several terminal nodes, the terminal node is connected to the base station module, the terminal node is located at the edge of the Zigbee network, and the coordinator node is connected to the PC host computer module.

[0085] In an embodiment of the present invention, preferably, the terminal node is connected to the base station module and is located at the edge of the Zigbee network. It is responsible for uploading the distance information measured by the UWB detection unit to the host computer and the time synchronization of the ultrasonic positioning, and is also called a child node; the coordinator node is connected to the PC host computer module, is the center of the entire network, and is also called a parent node.

[0086] As a preferred embodiment of the present invention, the specific steps of the Zigbee networking process are:

[0087] Step 1: The coordinator node and the terminal node initialize the hardware peripherals and the Zigbee protocol. The terminal node sends an active request to join the Zigbee network message. The routing node assigns a unique address to the terminal. The child node address is assigned by the parent node according to the following formula:

[0088]

[0089] Among them, C skip is the number of child nodes owned by node m; C m is the number of nodes controlled by node m; L m is the maximum network depth; d is the relative depth from node m to the routing node; R m is the number of nodes used for routing functions;

[0090] When C skip = 0, the node is a child node; when C skip >0, the node is the parent node; the address A of routing node n n For: A n =A parent +C skip (n-1)+1, where A parent is the address of the parent node of node n; the address of the child node l is A l For: A l =A parent +C skip R m +n, where Aparent is the address of the parent node of node l;

[0091] Step 2: The coordinator node searches for channels and establishes a network, adds nodes to the network, and runs Zigbee protocol tasks;

[0092] Step 3: The coordinator node loops to determine whether there is wireless information; the terminal node sends T after the ranging is completed. tof information;

[0093] Step 4: The coordinator node receives the wireless data and uploads it to the PC host computer. After the transmission is completed, the next data receiving task begins.

[0094] As a preferred embodiment of the present invention, the PC host computer module further processes the data summarized by the base station using the least square method and the three-sided positioning algorithm. The specific steps of the algorithm are:

[0095] Step 1: Take the geometric center point of the equilateral triangle formed by Zigbee base station No. 1, Zigbee base station No. 2, and Zigbee base station No. 3 as the coordinate origin, the extension line of the line connecting the geometric center point and base station 1 as the positive direction of the y-axis, and the positive direction of the x-axis rotated 90 degrees clockwise around the geometric center point to establish a rectangular coordinate system;

[0096] Step 2: Let the distances of Zigbee base station 1, Zigbee base station 2, and Zigbee base station 3 relative to the origin of the coordinate system be (x1, y1), (x2, y2), and (x3, y3), and let the coordinates of the seismograph node be (x, y). The three-side positioning algorithm gives:

[0097] s1 2 =(x-x1) 2 +(y-y1) 2 ;

[0098] s2 2 =(x-x2) 2 +(y-y2) 2 ;

[0099] s3 2 =(x-x3) 2 +(y-y3) 2 ;

[0100] Where: s1, s2, s3 are the distances from the projection points of Zigbee base station No. 1, Zigbee base station No. 2, and Zigbee base station No. 3 on the ground to the seismograph node respectively;

[0101] Step 3: Assume that the distance between the measured aerial positioning base point and the ground mobile node is L i(i=1,2,3), assuming the height of the known aerial positioning base point is H, then Solving the equation using the least squares method yields:

[0102]

[0103]

[0104] Among them, (x, y) is the coordinate of the seismograph node in the defined two-dimensional coordinate system.

[0105] In the embodiment of the present invention, preferably, Fig. 9 As shown, let s i (i=1,2,3) is the distance between the projection point of the positioning base station on the ground and the seismograph node. Then, three circles with s1, s2, and s3 as radii can be drawn to obtain the intersection point; Fig.10 As shown, the geometric center point of the equilateral triangle formed by Zigbee base station No. 1, Zigbee base station No. 2, and Zigbee base station No. 3 relative to it is taken as the coordinate origin, the extension line of the connection direction between the geometric center point and base station 1 is taken as the positive direction of the y-axis, and the positive direction of the x-axis is established by rotating the positive direction of the y-axis clockwise around the geometric center point by 90 degrees;

[0106] As a preferred embodiment of the present invention, the specific steps of wirelessly locating the seismograph node using UWB and ultrasound are as follows:

[0107] Step 1: Based on the placement of the base station in the positioning system, a two-dimensional plane coordinate system is established to obtain the base station coordinate information;

[0108] Step 2: Use UWB and ultrasound to measure the distance between the seismograph node and each base station;

[0109] Step 3: After preliminary screening, the effective distance information obtained by the base station is summarized to the PC host computer through Zigbee wireless communication;

[0110] Step 4: The PC host computer uses the trilateral positioning theory and the least squares method to solve the position information. After obtaining the position information of the cable-free seismograph, the PC host computer is used for human-computer interaction to navigate to the place where the seismograph is lost.

[0111] In the embodiment of the present invention, preferably, the flowchart of wireless positioning of seismograph nodes using UWB and ultrasound is as follows: Fig.11As shown in the figure, the human-computer interaction interface includes: real-time display of the positioning target location coordinates, and further calculation of the positioning target latitude and longitude using the predicted base station latitude and longitude; users can customize the range of the lost area. The human-computer interaction interface realizes the real-time display of the positioning target trajectory, accurately locates the target, and expands other application functions, such as the positioning target location latitude and longitude display, electronic fence warning, etc. The electronic fence warning function can customize the prohibited fence area. If the seismometer deviates from the area where it is located, the electronic fence function will be triggered to alarm.

[0112] The working principle of the present invention is:

[0113] The cable-free seismograph anti-loss search system based on UWB and ultrasound uses the joint positioning technology combining UWB and ultrasound, uses the TOA-based TWR algorithm for UWB ranging, uses the TDOA algorithm for ultrasonic ranging, combines the three-sided positioning theory with the least squares method for solution, and improves the positioning accuracy of the cable-free seismograph; through the use of UWB and ultrasonic dual positioning technology, the seismograph positioning system has double protection, which can improve the applicability of the cable-free seismograph in complex environments; Zigbee wireless communication units are used for wireless networking to realize positioning data transmission, ensure the reliability of data transmission, reduce equipment power consumption, greatly reduce the difficulty of base station installation, reduce the economic cost of positioning, and ensure the reliable operation of the equipment.

[0114] The above are only preferred embodiments of the present invention. It should be pointed out that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention. These should also be regarded as the protection scope of the present invention. These will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. A cable-free seismograph anti-loss search system based on UWB and ultrasound, characterized in that: include: A seismograph node module, the seismograph node module is used to send location information data of the cable-free seismograph; A base station module, the base station module includes a UWB detection unit, an ultrasonic receiving unit, a temperature measuring unit and a Zigbee wireless communication unit; the temperature measuring unit is used to measure the temperature of the surrounding environment; the UWB detection unit and the ultrasonic receiving unit are used to receive the location information data of the seismograph node, and the UWB detection unit and the ultrasonic receiving unit use the TOA-based TWR algorithm and the TDOA algorithm to calculate the distance between the seismograph node and the base station respectively; the Zigbee wireless communication unit is used for wireless networking between base stations, and is also used to realize time synchronization between base stations and data transmission between the base station and the data processing unit; A PC host computer module, which is used to further analyze and process the data collected by the base station; The specific steps for wireless positioning of seismograph nodes using UWB and ultrasound are as follows: Step 1: Based on the placement of the base station in the positioning system, a two-dimensional plane coordinate system is established to obtain the base station coordinate information; Step 2: Use UWB and ultrasound to measure the distance between the seismograph node and each base station; Step 3: After preliminary screening, the effective distance information obtained by the base station is summarized to the PC host computer through Zigbee wireless communication; Step 4: The PC host computer uses the trilateral positioning theory and the least squares method to solve the position information. After obtaining the position information of the cable-free seismograph, the PC host computer is used for human-computer interaction to navigate to the place where the seismograph is lost.

2. The cable-free seismograph anti-loss search system based on UWB and ultrasound according to claim 1 is characterized in that: The seismograph node module includes a UWB tag unit, a temperature measurement unit and an ultrasonic transmitting unit.

3. The cable-free seismograph anti-loss search system based on UWB and ultrasound according to claim 1 is characterized in that: The specific steps of the TWR algorithm are: Step 1: The beacon sends a signal to a single base station and records the time of sending the signal as τ AT1x ; Step 2: After the base station receives the signal, the time of receiving the signal is recorded as τ BR1x , then the base station delays for a fixed time t replyB , send a signal to the beacon and record the time τ of sending the signal BT1x ; Step 3: After the beacon receives the signal, record the time τ of receiving the signal AR1x , followed by a beacon delay of fixed time t replyA , send a signal to the base station and record the sending time τ AT2x ; Step 4: The base station receives the signal and records the time τ at which the signal is received BR2x , at this time, a two-way ranging is completed, and the distance between the beacon and the base station is calculated from the measured time: By roundA =2×T tof +t replyB , t roundB =2×T tof +t replyA It turns out that: According to the flight time T of the UWB signal between the seismograph node and the base station tof , calculate the distance between the seismograph node and a single base station, that is, d1 = c × T tof , where c≈3×10 8 m / s.

4. The cable-free seismograph anti-loss search system based on UWB and ultrasound according to claim 1 is characterized in that: The specific steps of the TDOA algorithm are: Step 1: The seismograph node sends a time synchronization signal to Zigbee base station No. 1, Zigbee base station No. 2, and Zigbee base station No. 3 at the same time, and transmits an ultrasonic signal at the same time. The seismograph node reads the temperature T1 detected by the temperature sensor; Step 2: Zigbee base station No. 1, Zigbee base station No. 2, and Zigbee base station No. 3 start the timer after receiving the time synchronization signal; Step 3: After receiving the ultrasonic signal, the timer of Zigbee base station No. 1, No. 2, and No. 3 stops timing, and then reads the temperature detected by the temperature sensor. According to the formula v of the influence of temperature on the speed of sound 声 =331.4+0.0607T, calculate the speed of sound at this time, from s=t×v 声 , calculate the distance s between each base station and the seismograph node, where t is the time recorded by the timer, and calculate the distances s1, s2, and s3 between Zigbee base station No. 1, Zigbee base station No. 2, and Zigbee base station No. 3 and the seismograph node in turn.

5. The cable-free seismograph anti-loss search system based on UWB and ultrasound according to claim 1 is characterized in that: The Zigbee network is a star network topology. The Zigbee network includes a coordinator node and several terminal nodes. The terminal nodes are connected to the base station module. The terminal nodes are located at the edge of the Zigbee network. The coordinator node is connected to the PC host computer module.

6. The cable-free seismograph anti-loss search system based on UWB and ultrasound according to claim 5, characterized in that: The specific steps of the Zigbee networking process are: Step 1: The coordinator node and the terminal node initialize the hardware peripherals and the Zigbee protocol. The terminal node sends an active request to join the Zigbee network message. The routing node assigns a unique address to the terminal. The child node address is assigned by the parent node according to the following formula: Among them, C skip is the number of child nodes owned by node m; C m is the number of nodes controlled by node m; L m is the maximum network depth; d is the relative depth from node m to the routing node; R m is the number of nodes used for routing functions; When C skip = 0, the node is a child node; when C skip >0, the node is the parent node; the address A of routing node n n For: A n =A parent +C skip (n-1)+1, where A parent is the address of the parent node of node n; the address of the child node l is A l For: A l =A parent +C skip R m +n, where A parent is the address of the parent node of node l; Step 2: The coordinator node searches for channels and establishes a network, adds nodes to the network, and runs Zigbee protocol tasks; Step 3: The coordinator node loops to determine whether there is wireless information; the terminal node sends T after the ranging is completed. tof information; Step 4: The coordinator node receives the wireless data and uploads it to the PC host computer. After the transmission is completed, the next data receiving task begins.

7. The cable-free seismograph anti-loss search system based on UWB and ultrasound according to claim 1 is characterized in that: The PC host module further processes the data collected by the base station using the least squares method and the three-sided positioning algorithm. The specific steps of the algorithm are: Step 1: Take the geometric center point of the equilateral triangle formed by Zigbee base station No. 1, Zigbee base station No. 2, and Zigbee base station No. 3 as the coordinate origin, the extension line of the line connecting the geometric center point and base station 1 as the positive direction of the y-axis, and the positive direction of the x-axis rotated 90 degrees clockwise around the geometric center point to establish a rectangular coordinate system; Step 2: Let the distances of Zigbee base station 1, Zigbee base station 2, and Zigbee base station 3 relative to the origin of the coordinate system be (x1, y1), (x2, y2), and (x3, y3), and let the coordinates of the seismograph node be (x, y). The three-side positioning algorithm gives: s1 2 =(x-x1) 2 +(y-y1) 2 ; <h2 style=";text-align:left;direction:ltr">s2<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> (x-x2)<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> +(y-y2)<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> ; <h2 style=";text-align:left;direction:ltr">s3<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> (x-x3)<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> +(y-y3)<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> ; Where: s1, s2, s3 are the distances from the projection points of Zigbee base station No. 1, Zigbee base station No. 2, and Zigbee base station No. 3 on the ground to the seismograph node respectively; Step 3: Assume that the distance between the measured aerial positioning base point and the ground mobile node is L i (i=1,2,3), assuming the height of the known aerial positioning base point is H, then Solving the equation by the least squares method yields: Among them, (x, y) is the coordinate of the seismograph node in the defined two-dimensional coordinate system.

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