CN102999986B - Detection method of embedded intrusion detection system based on ultrasonic phased array - Google Patents

Abstract

The invention discloses an embedded invasion detection system and a detection method based on an ultraphonic phase array. The embedded invasion detection system and the detection method have the advantages of being simple in structure, low in cost, easy to achieve and easy to adjust, having high stability, working all days and the like. The invasion detection system comprises a micro-programmed control unit (MCU) main control module, the ultraphonic phase array, a field programmable gata array (FPGA) time sequence control module and an ultrasonic transducer driving module connected in series, a signal amplification and conditioning module and a high-speed A/D conversion module connected in series, an output alarm module and a bus interface. A sensor technology bases on the ultraphonic phase array adopted by the embedded invasion detection system and the detection method based on the ultraphonic phase array not only has inherent advantages of an ultrasonic wave sensor, but also can overcome defects of an existing invasion detector, expands the applied range of the invasion detector, reduces the false alarm rate, improves measurement accuracy, forms a double inspection probe with an existing invasion detection technology, can improve prevention and control scope and effectiveness limitedly, and is a novel detection technology.

Description

Detection method of embedded intrusion detection system based on ultrasonic phased array

technical field

The invention relates to an intrusion detection system, in particular to an embedded intrusion detection system and detection method based on an ultrasonic phased array. It belongs to the field of sensor technology. the

Background technique

Ultrasonic phased array technology has been widely used in various aspects of industrial non-destructive testing, medical non-invasive testing and underwater acoustic detection. From the early one-dimensional detection to two-dimensional and three-dimensional imaging, its application range and detection accuracy are getting higher and higher. . Ultrasonic phased array is a one-dimensional or two-dimensional array composed of N ordinary ultrasonic transducers with large emission angles arranged according to a specific distribution in space, and transmits ultrasonic packets according to a specific timing and phase, forming a space. Each wave packet at a specific point (focus) produces coherent superposition (interference), and the superimposed ultrasonic wave is reflected back when it encounters an obstacle, and is received by the ultrasonic transducer. After signal processing at the receiving end, the obtained signal strength will obviously exceed the signal on the non-focus, so as to realize the detection of space obstacles at a specific position in front or obtain the distance information of obstacles; in addition, ultrasonic waves are transmitted according to specific timing and phase. , will form a highly directional narrow beam (compared to a single ultrasonic transducer) in the detection space, and will get accurate orientation information of the obstacle after encountering the obstacle and returning. The beam uses electronic scanning method (non-mechanical scanning) to quickly scan layer by layer in the detection space, so as to realize three-dimensional imaging (background image) of the orientation and distance of objects in the three-dimensional detection space. The obtained current image will be different from the background image to detect the occurrence of intrusion. With the development of electronic technology and sensor technology, people are constantly using the latest electronic technology development results to develop new intrusion detection sensors, such as infrared, microwave, ultrasonic sensors based on Doppler effect and echo detection technology. In order to reduce the false alarm rate (failure rate) of a single type of sensor, there are also multiple sensor sensors that integrate multiple sensors together. Among the above sensors, ultrasonic sensors are irreplaceable in some special applications because they will not be affected by environmental factors such as light, smoke, rain, snow, temperature, flammability and explosion. my country's national standard GB10408.2-1989 has detailed regulations on the technical standards of ultrasonic intrusion detectors. the

However, due to the limitations of the technology used, the ultrasonic intrusion detection sensor developed in accordance with the provisions of the national standard cannot accurately detect the intrusion body's orientation, shape size, moving direction, moving speed and other information, and for ultra-low speed (less than 0.3 meters /s) and ultra-high-speed (greater than less than 20 m/s) moving objects, the false alarm rate will increase rapidly, thus limiting its scope of application. Even if multiple probes distributed in different orientations are used, the above problems cannot be solved. the

In recent years, ultrasonic phased array technology has developed rapidly in many fields such as industrial flaw detection, medical treatment, and military affairs, but no relevant solutions and reports have been seen in the field of intrusion detection applications. the

The theoretical basis of ultrasonic phased array technology is as follows:

1. Multiple transmitting ultrasonic transducers are formed into an ultrasonic phased array according to a specific two-dimensional distribution, so that they can be focused into an ultrasonic beam in space. Under far-field conditions, assuming that each transducer has the same sensitivity, its main lobe width satisfies:

$\mathrm{<span\; class="notranslate">\; q</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; arcsin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; Nd</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; arcsin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}{\mathrm{<span\; class="notranslate">\; Nd</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

where q is the beam width, λ is the ultrasonic wavelength, N is the number of transducers in the array, d is the spacing of the transducers, and _θ0 is the orientation angle.

When θ is small, the above formula can be simplified as:

$\mathrm{<span\; class="notranslate">\; q</span>}<span\; class="notranslate">\; \&ap;</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}{\mathrm{<span\; class="notranslate">\; Nd</span>}\mathrm{<span\; class="notranslate">\; cos</span>}{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

It can be obtained from the above formula that as long as the wavelength λ, the number of arrays N and the spacing d of transducers are selected reasonably, the required beam width can be obtained. the

2. Assuming that the distance between a certain point T in space and the emission point F is l, and the propagation speed of the ultrasonic wave in the air is c, then the time t required for the ultrasonic wave to travel from point F to point T is:

t=l/c≈l/348 (3)

Therefore, by calculating the arrival time of each emission point at point T, the inversion can obtain the emission delay time of each emission point and the phase of the emission signal, so that the ultrasonic waves emitted by each emission point can be added in the same phase at point T to form a strong If there is an obstacle at point T, a strong echo signal will be detected within the time window of 2t±△t, otherwise only noise signals can be detected. Where 2△t is the window width. the

It can be seen from the above derivation that the narrow beam ensures the azimuth accuracy of the detection, and the focal point realizes the accurate measurement of the distance. By scanning different focal points in the detection area, an invisible fence with a certain length, width, and height can be formed in space, so that the orientation, speed, direction, quantity, geometric size, and even roughness of any intruding objects entering the fence can be monitored. The shape of the robot is measured, thereby realizing intrusion detection with multiple information, high precision, and a wide measurement range for moving speed. the

Chinese patent application 98122623.X discloses an ultrasonic comb detector array assembly, which is used to install on the surface of a measured object to apply ultrasonic signals to the measured object. This patent solves the difficulties encountered by the currently used comb detectors, which are fragile and prone to failure, the distance between the sensors is fixed and cannot be changed, and there is a gap when coupling with the measured object whose surface is not completely smooth, etc. That is, a structure of an ultrasonic array is proposed for a specific application. the

Chinese patent application 200480036233.1 discloses an ultrasonic transducer and a method of applying flip-chip two-dimensional array technology to a curved array including a supporting substrate, an integrated circuit and an array of piezoelectric elements. The support substrate has a non-linear surface. It belongs to an improvement of an assembly process technology. the

Chinese patent application 201010166913.2 discloses an array transducer for ultrasonic testing of non-metallic structures and its control system. Its defect is that the system can only detect the area of 60cm, not suitable for long-distance detection. the

Chinese patent application 201210024954.7 discloses an ultrasonic detector and an ultrasonic diagnostic device. The patent relates to an ultrasonic detector and an ultrasonic diagnostic device, which are only used in the medical field for diagnostic imaging of internal organs of the human body, and cannot be used for long-distance detection. the

To sum up, none of the above patents can realize long-distance scanning and detection of intruding objects, shape measurement, traveling direction and speed measurement, rough imaging and other functions. the

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art, and provide an intrusion detection system and detection method based on ultrasonic phased array, which has simple structure, low cost, easy implementation, easy adjustment, high stability and all-weather work advantages. The invention adopts the sensor technology based on ultrasonic phased array, not only has the inherent advantages of ultrasonic sensors, but also overcomes the shortcomings of existing intrusion detectors, expands the application range of intrusion detectors, reduces the false alarm rate, and improves the measurement accuracy , combined with the existing intrusion detection technology to form a multi-detection probe, which can limit the scope and effectiveness of prevention and control, and is a new type of detection technology. the

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

Embedded intrusion detection system based on ultrasonic phased array, including a MCU main control module,

An ultrasonic phased array,

An FPGA timing control module and an ultrasonic transducer driving module connected in series, the former is connected to the MCU main control module, the latter is connected to the ultrasonic phased array, and the ultrasonic transducer driving module follows the delay time set by the FPGA timing control module Sequentially send several square wave pulse signals with set phases to drive the ultrasonic phased array;

A signal amplification and conditioning module and a high-speed A/D conversion module are connected in series. The former is connected to the ultrasonic phased array, and the latter is connected to the MCU main control module. After the signal is amplified and filtered by the signal amplification and conditioning module, it is sent to the A/D conversion module, and finally converted into a digital signal and sent to the MCU main control module for processing; and

An output alarm module and a bus interface module are both connected to the MCU main control module, and the output alarm module provides a pair of contacts to the outside when an intrusion is detected to realize an audible and visual alarm; or, through the bus interface module, Send the alarm signal to the alarm control host (upper computer) through the universal bus, so as to realize the remote monitoring and linkage of the alarm. the

The MCU main control module is a 32-bit single-chip microcomputer based on the ARM Cortex-M3 core as the main control chip. the

The ultrasonic phased array is a plurality of transmitting ultrasonic transducers distributed in two-dimensional space. the

The signal amplification and conditioning module is an adjustable gain amplifier and an active band-pass filter. the

The receiving sensor is a receiving ultrasonic transducer. the

The detection method of embedded intrusion detection system based on ultrasonic phased array, the steps are as follows:

1) Two-dimensional spatial distribution of multiple transmitting ultrasonic transducers to form an ultrasonic phased array;

2) According to the different points to be scanned in space, the FPGA timing control module controls each transmitting ultrasonic transducer to emit a short beam of the same phase at different times through the ultrasonic transducer drive module, so as to realize the spatial focusing and scanning of the ultrasonic beam ;At the same time, the FPGA timing control module also sends a synchronous clock to the MCU main control module, thereby improving the detection accuracy;

3) If the focused ultrasonic wave encounters an obstacle near the focal point, it will be reflected back, and the receiving ultrasonic transducer will be used as a receiving sensor to receive the echo signal and convert it into an electrical signal;

4) After the signal is amplified and conditioned by the conditioning module, the received signal enters the A/D conversion module and is sent to the MCU main control module for processing; the MCU main control module forms a synchronization signal according to the calculated focal echo time to realize synchronous detection;

5) With the help of electronic scanning technology, the space to be detected is quickly layered and scanned, and the three-dimensional binary digital image of the object in the space fence area is formed and stored according to the echo signal; the fence area is obtained by detecting the difference between the digital images at different times The orientation, speed, direction, quantity, geometric size and even shape information of intruding objects. the

In the step 3), a plurality of receiving ultrasonic transducers are set as receivers to respectively receive echo signals of different focal points in different time periods. the

The MCU main control module also controls the FPGA timing control module to track and scan the intrusion object, so as to obtain the information of the intrusion object. the

For signals returned by obstacles in non-detection directions and non-focus points, the signal amplification and conditioning module can identify signals through pattern recognition and time windows. the

The beneficial effects of the present invention are:

1) The introduced FPGA technology completes the phase delay algorithm control, realizes the precise phase control of 8-channel data, provides the basis for the high-precision focusing of ultrasonic emission, and greatly improves the accuracy and simplicity of control. At the same time, FPGA has the characteristics of reconfigurable system parameters, which makes the design and modification of the system structure simpler and more flexible, and is more conducive to the monolithic integration of the system. the

2) Multiple specialized ultrasonic transducers are set as receivers to receive echo signals of different focal points at different time intervals, which improves the spatial scanning speed. the

3) ARM Cortex-M3 core microcontroller with high performance, low power consumption and low cost is used, which simplifies the hardware circuit and development environment, optimizes software programming, and reduces the complexity and cost of the system. the

4) The system has strong environmental adaptability. Ultrasonic is not affected by light, magnetic field, dust and other environmental factors, and has strong adaptability in harsh environments, especially in environments with corrosive gases, radiation, dust and explosive hazards. the

5) By making full use of the phased array, it can achieve arbitrary angle and depth focusing within the beam angle range, realize sector scanning within a certain space range, and can effectively obtain spatial information such as azimuth and distance of intruding obstacles, and can provide Obstacle shape information that cannot be provided by other similar systems. the

6) After testing, in the case of a sensor failure, other sensors can be put into work again through reorganization, thereby improving the robustness of the system, which is also a robot with high robust behavior in the real environment key. the

Description of drawings

Fig. 1 is a system block diagram of the present invention;

Figure 2(a) is a schematic diagram of excitation pulse signal transmission;

Figure 2(b) is a schematic diagram of ultrasonic focusing;

Figure 3 Plane view of ultrasonic phased array;

Fig. 4 is a schematic diagram of a section of the detection space of the present invention;

Fig. 5 is a schematic diagram of a scanning surface of discretization;

Figure 6(a) is the ultrasonic echo waveform measured after placing an obstacle at the focus (0°) position 1.5 meters away from the center of the phased array;

Figure 6(b) is the ultrasonic echo waveform measured after placing obstacles on the concentric circle at a distance of 1.5 meters from the center of the phased array at a position offset by 5° from the open focus;

Figure 6(c) is the ultrasonic echo waveform measured after an obstacle is placed on the concentric circle at a distance of 1.5 meters from the center of the phased array at a position offset by 20° from the open focus. the

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be noted that the following description is only for explaining the present invention and not limiting its content. the

As shown in Figure 1, the present invention comprises a MCU master control module, is the 32-bit single-chip microcomputer based on the ARM Cortex-M3 kernel as the master control chip;

An ultrasonic phased array is a plurality of emitting ultrasonic transducers distributed in two-dimensional space; in this embodiment, a 2×4 two-dimensional rectangular surface emitting array formed on a plane with eight ultrasonic transducers is placed The two ultrasonic transducers near the two long sides of the transmitting array surface are used as receiving sensors. These 10 ultrasonic transducers all use piezoelectric ceramic ultrasonic transducers with a center frequency of 40KHz and integrated transceivers. See the figure for details. 3 shown;

An FPGA timing control module and an ultrasonic transducer driving module connected in series, the former is connected to the MCU main control module, the latter is connected to the ultrasonic phased array, and the ultrasonic transducer driving module follows the delay time set by the FPGA timing control module Sequentially send several square wave pulse signals with set phases to drive the ultrasonic phased array;

A signal amplification and conditioning module and a high-speed A/D conversion module connected in series, the former is connected to the ultrasonic phased array, and the latter is connected to the MCU main control module, wherein the signal amplification and conditioning module is an adjustable gain amplifier and an active Band-pass filter; the signal returned from the focal point of the obstacle in front is converted into an electrical signal by receiving the ultrasonic transducer, and then sent to the high-speed A/D conversion module after a series of amplification and filtering by the signal amplification and conditioning module. Convert it into a digital signal and send it to the MCU main control module for processing; and

An output alarm module and a bus interface module are both connected to the MCU main control module, and the output alarm module provides a pair of contacts to the outside when an intrusion is detected to realize the sound and light alarm; or, through the bus interface module, the alarm The signal is sent to the alarm control host (host computer) through the universal bus, so as to realize the remote monitoring and linkage of the alarm. the

The invention takes the STM32F407 single-chip microcomputer of STMicroelectronics as the core, and realizes the control and response to the functional modules of each part. After the FPGA timing control module obtains the scan start signal from the MCU main control module of the system, it will sequentially send excitation pulse signals according to the predetermined rules and timing. However, due to the limited signal power output by the FPGA timing control module, it is necessary to drive the ultrasonic transducer. Amplify the excitation pulse signal. After each scanning point is completed, according to the pre-calculated value, the timing control module sends a frame synchronization signal and a position synchronization signal to the MCU main control module when the echo signal reaches the receiving probe, and informs the MCU main control module to start A/D conversion , while improving the detection accuracy. If the MCU main control module does not receive the frame synchronization signal for a certain period of time, it means that an error occurred during the scanning process. At this time, the FPGA timing control module should be forced to restart and re-scan. In order to improve the spatial scanning speed, in this embodiment, two special ultrasonic transducers are set as receivers to receive echo signals of different focal points at different time periods, see Figures 1, 2(a) and 2 for details (b). For the signal returned from the focal point of the obstacle in front of the ultrasound, the MCU main control module adjusts the position and direction of the focus by controlling the FPGA timing control module and the ultrasonic transducer drive module to excite each transmitting ultrasonic transducer according to certain rules and timing. In this way, it is convenient to realize the scanning and detection of the specific area ahead, and obtain the spatial information of the intruding object on the cross section according to the received and processed echo signal; the drive module sequentially sends several certain power The square wave pulse signal drives the ultrasonic phased array; after the focused ultrasonic wave encounters an obstacle near the focus and is reflected back, the ultrasonic echo signal needs to be converted into an electrical signal, and the converted electrical signal is weak and needs to be amplified; the ultrasonic sensor The transmitted ultrasonic signal is a spherical wave, and the received echo signal may be reflected from various angles, and noise will be introduced after a high amplification factor. In order to minimize the noise signal, it is necessary to filter the amplified signal; after amplification and filtering After the signal is processed, it is sent to a high-speed A/D conversion circuit, and the digital signal after A/D conversion is sent to STM32F103 for processing. Specifically complete the wave detection, the algorithm for determining the focus position, the threshold detection, the zero-crossing detection, the wavelet transform and other processing. The MCU main control module controls the ultrasonic beam emitted by the ultrasonic phased array through the FPGA timing control module and the driving module, and scans all the focal points on the section in turn to form a focus on a specific focal point on the section at a specific distance in front, and according to The echo signal forms the 2D digital information of the intruder on the cross section; after the system scans the environment, it returns the corresponding prompt information according to the scanning result, and gives clear instructions to the user's next action through the alarm output module; the intrusion obstacle information also It will be connected with various information output devices through the bus interface, such as sending to the host computer. the

Referring to FIG. 1 , the present invention takes the embedded system as the core and uses the ultrasonic phased array as the sensor to construct a system capable of realizing intrusion detection of the detection space. The system can realize obstacle scanning detection, shape measurement, travel speed measurement, azimuth measurement, rough imaging functions, and can realize related information output. the

The detection method of embedded intrusion detection system based on ultrasonic phased array, the steps are as follows:

1) Two-dimensional spatial distribution of multiple transmitting ultrasonic transducers to form an ultrasonic phased array;

2) According to the different points to be scanned in space, the FPGA timing control module controls each transmitting ultrasonic transducer to emit a short beam of the same phase at different times through the ultrasonic transducer drive module, so as to realize the spatial focusing and scanning of the ultrasonic beam; At the same time, the FPGA timing control module also sends a synchronous clock to the CPU module, thereby improving the detection accuracy;

3) The focused ultrasonic wave will be reflected back if it encounters an obstacle near the focal point, and the receiving ultrasonic transducer is used as the receiving sensor to receive the echo signal and convert it into an electrical signal: set multiple receiving ultrasonic transducers as receiving The device receives the echo signals of different focal points in different time periods respectively;

4) After the signal is amplified and conditioned by the conditioning module, the received signal enters the A/D conversion module and is sent to the MCU main control module for processing; the MCU main control module forms a synchronization signal according to the calculated focal echo time to realize synchronous detection;

5) With the help of electronic scanning technology, the space to be detected is quickly layered and scanned, and the three-dimensional binary digital image of the object in the space fence area is formed and stored according to the echo signal; the fence is obtained by performing difference detection on the digital images at different times The orientation, speed, direction, quantity, geometric size and even shape information of intruding objects in the area. the

The MCU main control module also controls the FPGA timing control module to track and scan the intrusion object, so as to obtain the information of the intrusion object. the

For signals returned by obstacles in non-detection directions and non-focus points, the signal amplification and conditioning module can identify signals through pattern recognition and time windows. the

Combined with Figure 1, when the resolution of space obstacles is not high, the whole system can be simplified by reducing the discretization of the section and simplifying the structure of the phased array. The main functions realized are:

(1) Ultrasonic emission, data reception, data processing, storage and prompt information output functions. the

⑵Recognition of intruding objects, scanning image formation, signal amplification, graphic information output and data storage functions. the

(3) Ultrasonic transmission delay, phase control of transmitted signals, signal acquisition, time window processing of received signals, coordinate positioning of image signals and real-time information output functions. the

(4) Measure the driving parameters (speed, direction, etc.) and general shape of the intruding object by memorizing the obtained information. the

In conjunction with Figure 3, the ultrasonic phased array uses 8 TCF40-18TR1 piezoelectric ceramic ultrasonic transducers with a center frequency of 40KHz and integrated transceivers to form a simplified two-dimensional rectangular array. Under the control of the FPGA timing module, through Delayed triggering (realizing emission focus), synchronous triggering (controlling the phase of the emission signal) and timing emission (scanning on different sections) form a scanning function for different focal points and different sections. Ultrasonic transducers can emit ultrasonic waves independently or simultaneously as required to form beams focused in space. the

Referring to Figures 4 and 5, the space barrier area scanned by the present invention is a space with a certain depth, width and height at a certain distance from the array. This embodiment adopts a rectangular space, the nearest section center is 3.5 meters away from the center of the phased array, the farthest section center is 5.5 meters away from the center of the phased array, the height of the lower side from the ground is 100 mm, the height of the upper side from the ground is 1900 mm, and the left and right width About 1800mm (can be adjusted according to needs); see Figure 4 and Figure 5 for details. the

Combining Figures 3, 4, and 5, by arranging the focal points of each scanning plane in a staggered manner, sufficient density of scanning points can be formed in the monitoring space. In order to simplify the system design, this embodiment adopts the working mode of multi-send and multi-receive. If the method of scanning sequentially after the complete scanning procedure of transmitting and receiving is adopted for each focal point, the time required to scan a section is too long, and it cannot be guaranteed that all scanned focal points are near the same plane . In order to reduce the time required for scanning, by rationally arranging the order of scanning points, the echoes of each focus can reach the receiving transducer in turn according to the width of the given time window, which can effectively reduce the time required for scanning. the

On the premise that the position of the scanning focus remains unchanged, in order to speed up the scanning, the parameters of each spatial scanning point can be calculated in advance and made into a table, and the scanning can be realized by looking up the table. In this embodiment, the finite state machine of the FPGA timing control module is used to realize functions such as ultrasonic signal generation, beam scanning, phase control, and transmission period control. The FPGA timing control module also sends a frame synchronization signal and a focus synchronization signal to the MCU main control module for precise positioning of the focus point of the signal processing module. the

Figure 6 shows the graphs of focused and non-focused signals under the same obstacle, where Figure 6(a) is the ultrasonic wave measured at the focus (0°) position 1.5 meters away from the center of the phased array after placing an obstacle The echo waveform, Figure 6(b) is the ultrasonic echo waveform measured after placing obstacles on the concentric circle at a distance of 1.5 meters from the center of the phased array at a position offset by 5° from the open focus, and Figure 6(c) is Measure the ultrasonic echo waveform after placing obstacles on the concentric circle at a distance of 1.5 meters from the center of the phased array at a position offset by 20° from the open focus. It can be seen from these three figures that after focusing by the phased array, most of the ultrasonic energy is concentrated within a range of about 5° near the focus. From the formula (2), if N and d are changed appropriately, the focused ultrasonic energy can be more concentrated when other conditions remain unchanged. the

The system involved in the present invention is an embedded system, which can form an independent intrusion detection system together with necessary external output modules, and can also be used as a module to cooperate with other detectors to form a multi-intrusion detection system. the

Although the specific implementation of the present invention has been described above in conjunction with the accompanying drawings, it does not limit the protection scope of the present invention. On the basis of the technical solution of the present invention, those skilled in the art can make various Modifications or variations are still within the protection scope of the present invention. the

Claims (1)

1. a detection method for the embedded intrusion detection system based on ultrasonic phase array, is characterized in that, step is as follows:

1) multiple transmitting ultrasonic transducers are carried out to two-dimensional space distribution and constitution ultrasonic phased array;

2) FPGA time-sequence control module, according to the difference of space point to be scanned, not sending separately in the same time a branch of synchronous shortwave bundle, is realized space-focusing and the scanning of ultrasonic beam by each transmitting ultrasonic transducer of ultrasonic transducer driver module control; Meanwhile, FPGA time-sequence control module also sends synchronous clock to MCU main control module, thereby improves accuracy of detection;

3), if will reflect when the ultrasound wave after focusing on runs into barrier near focus, receive echoed signal by receiving ultrasonic transducer as receiving sensor, and convert electric signal to;

4) signal receiving, after the amplification conditioning of signal amplification and conditioning module, enters high-speed a/d modular converter and delivers to MCU main control module and process; MCU main control module forms synchronizing signal according to the focus echo time calculating, and realizes synchronously and detecting;

5) treat space exploration by means of electronic scanning technique and carry out fast hierarchical scanning, form three-dimensional binary digital image the storage of object in fence region, space according to echoed signal; By to not in the same time digital picture carry out difference detection, obtain orientation, speed, trend, quantity, physical dimension and even the appearance information of intrusion object in this fence region;

In described step 3), multiple reception ultrasonic transducers are set as receiver, in the different periods, not confocal echoed signal are received respectively;

MCU main control module is also controlled FPGA time-sequence control module intrusion object is realized to spotting scaming, to obtain the information of intrusion object;

The signal returning for the barrier in non-detection direction, non-focus, signal amplifies and conditioning module can be screened by the pattern-recognition of signal and time window;

The described embedded intrusion detection system based on ultrasonic phase array, comprise a MCU main control module, one ultrasonic phased array, the FPGA phase place time-sequence control module being connected in series and a ultrasonic transducer driver module, the former is connected in MCU main control module, the latter is connected in ultrasonic phased array, sends successively several square-wave pulse signals of setting phase place the time delay that ultrasonic transducer driver module is set according to FPGA phase place time-sequence control module and drives ultrasonic phased array;

The signal amplification being connected in series and conditioning module and a high-speed a/d modular converter, the former is connected in ultrasonic phased array, the latter is connected in MCU main control module, the signal being returned by front barrier focal position converts to after electric signal by receiving sensor, amplify and conditioning module is delivered to high-speed a/d modular converter after carrying out a series of amplification, filtering through signal, finally convert digital signal to and deliver to the processing of MCU main control module; And

One outputting alarm module and a bus interface module, be all connected in MCU main control module, and described outputting alarm module externally provides pair of contact in the time invasion generation being detected, is used for realizing sound and light alarm; Or, by bus interface module, alerting signal is sent to controlling alarm main frame by versabus, thereby realizes warning remote monitoring and interlock.