阅读说明：本技术 一种基于传感网络的智能门禁系统 (Intelligent access control system based on sensing network ) 是由 左青松 于 2019-11-13 设计创作，主要内容包括：本发明提供一种基于传感网络的智能门禁系统,基于传感网络的智能门禁系统包括中央处理装置、温度传感器、信号处理电路、指纹采集模块、摄像头、第一触发模块、温度识别模块、指纹识别模块、第二触发模块、图像识别模块、第三触发模块、闸门控制模块、非门电路以及报警模块,其中,使用温度传感器确认进入门禁的为人体,使用信号处理电路提高了温度监测精度,当监测到为人体时,触发指纹采集模块进行指纹采集作业,当采集到的指纹为允许进入门禁的人员的指纹时再进一步触发摄像头进行图像采集,再由图像识别模块提取图像的特征信息以再进一步判断进入门禁的是否为允许进入门禁的人员。(The invention provides an intelligent access control system based on a sensor network, which comprises a central processing unit, a temperature sensor, a signal processing circuit, a fingerprint acquisition module, a camera, a first trigger module, a temperature identification module, a fingerprint identification module, a second trigger module, an image identification module, a third trigger module, a gate control module, a NOT gate circuit and an alarm module, wherein, the temperature sensor is used for confirming that the entrance guard is a human body, the signal processing circuit is used for improving the temperature monitoring precision, when the person who is monitored is a human body, the fingerprint acquisition module is triggered to perform fingerprint acquisition operation, when the acquired fingerprint is the fingerprint of the person who is allowed to enter the entrance guard, the camera is further triggered to perform image acquisition, and the image identification module extracts the characteristic information of the image so as to further judge whether the person who enters the entrance guard is the person who is allowed to enter the entrance guard.)

1. An intelligent access control system based on a sensing network is characterized by comprising a central processing unit, a temperature sensor, a signal processing circuit, a fingerprint acquisition module, a camera, a first trigger module, a temperature identification module, a fingerprint identification module, a second trigger module, an image identification module, a third trigger module, a gate control module, a non-gate circuit and an alarm module;

wherein, the output end of the temperature sensor is connected with the input end of the signal processing circuit, the output end of the signal processing circuit is connected with the input end of the central processing device, the output end of the fingerprint acquisition module is connected with the input end of the central processing device, the output end of the camera is connected with the input end of the central processing device, the output end of the central processing device is connected with the input end of the temperature identification module, the output end of the temperature identification module is connected with the input end of the first trigger module, the output end of the first trigger module is connected with the input end of the fingerprint acquisition module, the output end of the central processing device is connected with the input end of the fingerprint identification module, the output end of the fingerprint identification module is connected with the input end of the second trigger module, the output end of the second trigger module is connected with the input end of the camera, the output end of the central processing unit is connected with the input end of the image recognition module, the output end of the image recognition module is connected with the input end of the third trigger module, the output end of the third trigger module is connected with the input end of the gate control module, the output end of the second trigger module is connected with the input end of the NOT gate circuit, the output end of the NOT gate circuit is connected with the input end of the alarm module, the output end of the third trigger module is connected with the input end of the NOT gate circuit, and the output end of the NOT gate circuit is connected with the input end of the alarm module;

wherein, the temperature sensor is used for collecting the temperature signal of an object to be entered into the door control and transmitting the collected temperature signal to the signal processing circuit, the signal processing circuit processes the received temperature signal, the signal processing circuit transmits the processed temperature signal to the central processing unit, the central processing unit transmits the received temperature signal to the temperature identification module, a standard temperature range is stored in the temperature identification module, if the temperature signal received by the temperature identification module is in the standard temperature range, the door control to be entered into the door control is considered to be a human body, the temperature identification module controls the first trigger module to transmit a first trigger signal to the fingerprint collection module, the fingerprint collection module starts to collect the fingerprint image of the person to be entered into the door control after receiving the first trigger signal, the fingerprint acquisition module transmits the acquired fingerprint image to the central processing unit, the central processing unit transmits the received fingerprint image to the fingerprint identification module, fingerprint information allowing entrance guard personnel to enter is stored in the fingerprint identification module, if the fingerprint image information received by the fingerprint identification module is matched with any one of the stored fingerprint information allowing entrance guard personnel, the fingerprint identification module controls the second trigger module to send a second trigger signal to the camera, if the fingerprint image received by the fingerprint identification module is not matched with any one of the stored fingerprint information allowing entrance guard personnel, the second trigger module sends a low level signal to the NOT-gate circuit, and the NOT-gate circuit changes the received low level into a high level and then transmits the high level signal to the alarm module, the alarm module starts alarm operation after receiving a high-level signal, the camera is arranged above the fingerprint acquisition module, the camera starts to acquire facial image information of people waiting to enter the entrance guard after receiving a second trigger signal, the camera transmits the acquired facial image information to the central processing device, the central processing device transmits the received facial image information to the image identification module, the image identification module stores standard characteristic quantity of the facial image information of people allowing to enter the entrance guard, the image identification module extracts characteristic quantity of the facial image information received by the image identification module, the standard characteristic quantity and the characteristic quantity extracted by the image identification module are the same parameter, if the characteristic quantity extracted by the image identification module is matched with the standard characteristic quantity stored by the image identification module, the image identification module controls the third trigger module to send a third trigger signal to the gate control module And the gate control module receives the third trigger signal and then opens the gate of the entrance guard, if the characteristic quantity extracted by the image recognition module is not matched with the standard characteristic quantity stored by the image recognition module, the third trigger module sends a low level signal to the NOT gate circuit, the NOT gate circuit changes the received low level into a high level and then transmits the high level signal to the alarm module, and the alarm module starts alarm operation after receiving the high level signal.

2. The intelligent entrance guard system based on sensor network as claimed in claim 1, wherein the image recognition module extracts the feature quantity of the facial image information received by the image recognition module, and the feature quantity is the distance between the midpoint of the two nosewings and the midpoint of the two eyes in the facial image.

3. The intelligent access control system based on the sensing network according to claim 2, wherein the method for extracting the distance between the midpoint of the two nosewings and the midpoint of the two eyes in the facial image by the image recognition module is as follows:

s1: extracting coordinates (x) of the left eye in a face image₁，y₁) Coordinates of the right eye (x)₂，y₂) Coordinates of the left alar₃，y₃) And the coordinates (x) of the right alar₄，y₄）；

S2: calculating the coordinates (x) of the midpoints of two nasal wings₅，y₅) Wherein, in the step (A),

s3: the distance b between the left and right eye is determined, wherein,

s4: solving the equation of a straight line formed by connecting the left eye and the right eye:

s4: extracting the distance h between the midpoints of the two nasal wings and the midpoints of the two eyes in the face image, wherein,

4. the intelligent entrance guard system based on sensor network as claimed in claim 1, wherein the temperature sensor is used to collect the temperature signal of the object to be entered into the entrance guard, convert the collected temperature signal into a voltage signal V0, and transmit the voltage signal V0 to the signal processing circuit, V1 is the voltage signal processed by the signal processing circuit, the signal processing circuit comprises a signal amplifying unit and a signal filtering unit, the output end of the temperature sensor is connected with the input end of the signal amplifying unit, the output end of the signal amplifying unit is connected with the input end of the signal filtering unit, and the output end of the signal filtering unit is connected with the input end of the central processing unit.

5. The intelligent entrance guard system based on sensor network as claimed in claim 4, wherein the signal amplification unit comprises operational amplifier A1, capacitor C1-C3 and resistor R1-R7;

wherein, the output end of the temperature sensor is connected with one end of a resistor R1, the other end of a resistor R1 is grounded, one end of a resistor R1 is further connected with one end of a capacitor C1, one end of a resistor R3 is grounded, the other end of a resistor R3 is connected with the other end of a capacitor C1, one end of a resistor R2 is connected with the non-inverting input end of an operational amplifier A1, one end of a resistor R2 is further connected with the other end of a resistor R3, the other end of a resistor R2 is connected with a DC power supply Vcc, the V + end of an operational amplifier A1 is connected with the DC power supply Vcc, the V-end of an operational amplifier A1 is grounded, one end of a capacitor C2 is grounded, the other end of a capacitor C2 is connected with one end of a resistor 686R 9, the other end of a resistor R4 is connected with the inverting input end of an operational amplifier A1, the other end of a resistor R4 is connected with one end of a resistor R5, the other end of a resistor R, the other end of the capacitor C3 is connected with one end of the resistor R6, one end of the resistor R7 is grounded, the other end of the resistor R7 is connected with the other end of the resistor R6, and the other end of the resistor R6 is connected with the input end of the signal filtering unit.

6. The intelligent entrance guard system based on sensor network as claimed in claim 5, wherein the signal filtering unit comprises resistors R8-R11, capacitors C4-C7 and an operational amplifier A2;

wherein, the output end of the signal amplifying unit is connected with one end of a capacitor C4, the other end of the capacitor C4 is connected with one end of a resistor R8, the other end of a resistor R8 is connected with a DC power supply Vcc, one end of a resistor R9 is grounded, the other end of a resistor R9 is connected with the other end of a capacitor C4, the other end of a resistor R9 is connected with one end of a resistor R10, one end of a resistor R10 is connected with one end of a resistor R11, the other end of a resistor R10 is connected with one end of a capacitor C5, the other end of a capacitor C5 is connected with the inverting input end of an operational amplifier A2, the other end of a capacitor C5 is further connected with the output end of an operational amplifier A2, the V + end of an operational amplifier A2 is connected with the DC power supply Vcc, the V-end of an operational amplifier A2 is grounded, one end of a capacitor C9 is grounded, the other end of a capacitor C6 is connected with the non-inverting, one end of the capacitor C7 is connected with the output end of the operational amplifier A2, the other end of the capacitor C7 is connected with the input end of the central processing device, and the signal filtering unit transmits a voltage signal V1 to the central processing device.

Technical Field

The invention relates to the field of intelligent electromechanics, in particular to an intelligent access control system based on a sensing network.

Background

The development of the current social science and technology level is rapid, the information technology is a leading army of the scientific and technology development level, and various scientific and technology levels based on the information technology are changed day by day. People feel the convenience brought to life by the high-speed development of the scientific level at any time, and meanwhile, the demand is provided for the development direction of science and technology. Although the scientific and technological development brings convenience to the life of people, new potential safety hazards are brought at the same time, and the behaviors of criminals utilizing high technology are gradually increased. The traditional door lock system can not meet the requirements of the current society, and an intelligent access control system is born, so that the safety of the door is effectively improved, and meanwhile, the convenience and the like are improved.

The access control system has also gained rapid promotion and progress on the basis of the high-speed development of the radio frequency identification technology, and the present access control system is more and more complete and the usability is more and more perfect. And continuously deriving a new technical application system on the basis, the door control system has more excellent performances in the aspects of safety, convenience, manageability and the like, and the door control system is not only the replacement application of a door and a key, but also forms a more and more perfect system in the field of access management control more gradually. Nowadays, personnel attendance systems, work environment safety limits and other management fields are not lack of the figure of the radio frequency identification technology, and play more and more important roles.

The access control system is an effective means for blocking outside people, and is widely concerned by people. Common access control systems can be divided into mechanical type, access control card type, keyboard type coded lock, internet type, biological characteristic type and the like, wherein the mechanical type access control uses a mechanical door lock and a key to open the access control, and the mode has long history, is stable and reliable, but requires a user to find out the key during use, and has a complex process. The entrance guard card uses IC card (IC card) as the discrimination mode, which is similar to the key door, but it is stable and reliable, but it has the problem of inconvenient access. The keyboard type coded lock judges whether the visitor is a legal user or not by inputting the password, the illegal user can remember the password when other people input the password, and the security is low. The internet type access control is a novel access control mode, and an access control system is mainly controlled through remote operation, such as control through a mobile phone.

Disclosure of Invention

Therefore, in order to overcome the above problems, the present invention provides an intelligent access control system based on a sensor network, which comprises a central processing unit, a temperature sensor, a signal processing circuit, a fingerprint acquisition module, a camera, a first trigger module, a temperature identification module, a fingerprint identification module, a second trigger module, an image identification module, a third trigger module, a gate control module, a non-gate circuit and an alarm module, wherein, the temperature sensor is used for confirming that the entrance guard is a human body, the signal processing circuit is used for improving the temperature monitoring precision, when the person who is monitored is a human body, the fingerprint acquisition module is triggered to perform fingerprint acquisition operation, when the acquired fingerprint is the fingerprint of the person who is allowed to enter the entrance guard, the camera is further triggered to perform image acquisition, and the image identification module extracts the characteristic information of the image so as to further judge whether the person who enters the entrance guard is the person who is allowed to enter the entrance guard.

The intelligent access control system based on the sensing network comprises a central processing unit, a temperature sensor, a signal processing circuit, a fingerprint acquisition module, a camera, a first trigger module, a temperature identification module, a fingerprint identification module, a second trigger module, an image identification module, a third trigger module, a gate control module, a NOT gate circuit and an alarm module.

Wherein, the output end of the temperature sensor is connected with the input end of the signal processing circuit, the output end of the signal processing circuit is connected with the input end of the central processing device, the output end of the fingerprint acquisition module is connected with the input end of the central processing device, the output end of the camera is connected with the input end of the central processing device, the output end of the central processing device is connected with the input end of the temperature identification module, the output end of the temperature identification module is connected with the input end of the first trigger module, the output end of the first trigger module is connected with the input end of the fingerprint acquisition module, the output end of the central processing device is connected with the input end of the fingerprint identification module, the output end of the fingerprint identification module is connected with the input end of the second trigger module, the output end of the second trigger module is connected with the input end of the camera, the output end of the image recognition module is connected with the input end of a third trigger module, the output end of the third trigger module is connected with the input end of a gate control module, the output end of a second trigger module is connected with the input end of a non-gate circuit, the output end of the non-gate circuit is connected with the input end of an alarm module, the output end of the third trigger module is connected with the input end of the non-gate circuit, and the output end of the non-gate circuit is connected with the input end of the alarm module.

Wherein, the temperature sensor is used for collecting the temperature signal of an object to enter the door control and transmitting the collected temperature signal to the signal processing circuit, the signal processing circuit processes the received temperature signal, the signal processing circuit transmits the processed temperature signal to the central processing device, the central processing device transmits the received temperature signal to the temperature identification module, the temperature identification module stores a standard temperature range, if the temperature signal received by the temperature identification module is in the standard temperature range, the door control is considered to be a human body, the temperature identification module controls the first trigger module to transmit a first trigger signal to the fingerprint collection module, the fingerprint collection module starts to collect the fingerprint image of the person to enter the door control after receiving the first trigger signal, the fingerprint collection module transmits the collected fingerprint image to the central processing device, the central processing unit transmits the received fingerprint image to the fingerprint identification module, fingerprint information allowing entrance guard personnel is stored in the fingerprint identification module, if the fingerprint image information received by the fingerprint identification module is matched with any one of the stored fingerprint information allowing entrance guard personnel, the fingerprint identification module controls the second trigger module to send a second trigger signal to the camera, if the fingerprint image received by the fingerprint identification module is not matched with any one of the stored fingerprint information allowing entrance guard personnel, the second trigger module sends a low level signal to the NOT-gate circuit, the NOT-gate circuit changes the received low level into a high level and then transmits the high level signal to the alarm module, the alarm module starts alarm operation after receiving the high level signal, the camera is arranged above the fingerprint acquisition module, and the camera starts to acquire facial image information of the entrance guard personnel after receiving the second trigger signal, the camera transmits the collected facial image information to the central processing device, the central processing device transmits the received facial image information to the image recognition module, the standard characteristic quantity of the facial image information allowing entrance of an entrance guard is stored in the image recognition module, the image recognition module extracts the characteristic quantity of the facial image information received by the image recognition module, the standard characteristic quantity and the characteristic quantity extracted by the image recognition module are the same parameter, if the characteristic quantity extracted by the image recognition module is matched with the standard characteristic quantity stored by the image recognition module, the image recognition module controls the third trigger module to send a third trigger signal to the gate control module, the gate control module opens the gate of the entrance guard after receiving the third trigger signal, and if the characteristic quantity extracted by the image recognition module is not matched with the standard characteristic quantity stored by the image recognition module, the third trigger module sends a low level signal to the NOT-gate circuit, the NOT gate circuit changes the received low level into high level and then transmits the high level to the alarm module, and the alarm module starts alarm operation after receiving a high level signal.

Preferably, the image recognition module extracts a feature quantity of the face image information received by the image recognition module, wherein the feature quantity is a distance between a midpoint of two nosewings and a midpoint of two eyes in the face image.

Preferably, the method for extracting the distance between the midpoint of the two nasal wings and the midpoint of the two eyes in the facial image by the image recognition module is as follows:

s1: extracting coordinates (x) of the left eye in a face image₁，y₁) Coordinates of the right eye (x)₂，y₂) Coordinates of the left alar₃，y₃) And the coordinates (x) of the right alar₄，y₄）；

S2: calculating the coordinates (x) of the midpoints of two nasal wings₅，y₅) Wherein, in the step (A),

；

s3: the distance b between the left and right eye is determined, wherein,

；

s4: solving the equation of a straight line formed by connecting the left eye and the right eye:

；

s4: extracting the distance h between the midpoints of the two nasal wings and the midpoints of the two eyes in the face image, wherein,

。

preferably, the temperature sensor is used for collecting temperature signals of an object to be entered into the door control, the collected temperature signals are converted into voltage signals V0, the voltage signals V0 are transmitted to the signal processing circuit, V1 is the voltage signals processed by the signal processing circuit, the signal processing circuit comprises a signal amplification unit and a signal filtering unit, the output end of the temperature sensor is connected with the input end of the signal amplification unit, the output end of the signal amplification unit is connected with the input end of the signal filtering unit, and the output end of the signal filtering unit is connected with the input end of the central processing device.

Preferably, the signal amplifying unit includes an operational amplifier A1, capacitors C1-C3, and resistors R1-R7.

Wherein, the output end of the temperature sensor is connected with one end of a resistor R1, the other end of a resistor R1 is grounded, one end of a resistor R1 is further connected with one end of a capacitor C1, one end of a resistor R3 is grounded, the other end of a resistor R3 is connected with the other end of a capacitor C1, one end of a resistor R2 is connected with the non-inverting input end of an operational amplifier A1, one end of a resistor R2 is further connected with the other end of a resistor R3, the other end of a resistor R2 is connected with a DC power supply Vcc, the V + end of an operational amplifier A1 is connected with a DC power supply Vcc, the V-end of an operational amplifier A1 is grounded, one end of a capacitor C2 is grounded, the other end of a capacitor C2 is connected with one end of a resistor 686R 9, the other end of a resistor R4 is connected with the inverting input end of an operational amplifier A1, the other end of a resistor R4 is connected with one end of a resistor R5, the other end of a resistor, the other end of the capacitor C3 is connected with one end of the resistor R6, one end of the resistor R7 is grounded, the other end of the resistor R7 is connected with the other end of the resistor R6, and the other end of the resistor R6 is connected with the input end of the signal filtering unit.

Preferably, the signal filtering unit includes resistors R8-R11, capacitors C4-C7, and an operational amplifier A2.

Wherein, the output end of the signal amplifying unit is connected with one end of a capacitor C4, the other end of the capacitor C4 is connected with one end of a resistor R8, the other end of a resistor R8 is connected with a DC power supply Vcc, one end of a resistor R9 is grounded, the other end of a resistor R9 is connected with the other end of a capacitor C4, the other end of a resistor R9 is connected with one end of a resistor R10, one end of a resistor R10 is connected with one end of a resistor R11, the other end of a resistor R10 is connected with one end of a capacitor C5, the other end of a capacitor C5 is connected with the inverting input end of an operational amplifier A2, the other end of a capacitor C5 is further connected with the output end of an operational amplifier A2, the V + end of an operational amplifier A2 is connected with the DC power supply Vcc, the V-end of an operational amplifier A2 is grounded, one end of a capacitor C9 is grounded, the other end of a capacitor C6 is connected with the non-, one end of the capacitor C7 is connected with the output end of the operational amplifier A2, the other end of the capacitor C7 is connected with the input end of the central processing device, and the signal filtering unit transmits the voltage signal V1 to the central processing device.

Compared with the prior art, the invention has the following beneficial effects:

(1) the invention provides an intelligent access control system based on a sensing network, which comprises a central processing unit, a temperature sensor, a signal processing circuit, a fingerprint acquisition module, a camera, a first trigger module, a temperature identification module, a fingerprint identification module, a second trigger module, an image identification module, a third trigger module, a gate control module, a NOT gate circuit and an alarm module, wherein, the temperature sensor is used for confirming that the entrance guard is a human body, the signal processing circuit is used for improving the temperature monitoring precision, when the person who is monitored is a human body, the fingerprint acquisition module is triggered to perform fingerprint acquisition operation, when the acquired fingerprint is the fingerprint of the person who is allowed to enter the entrance guard, the camera is further triggered to perform image acquisition, and the image identification module extracts the characteristic information of the image so as to further judge whether the person who enters the entrance guard is the person who is allowed to enter the entrance guard.

(2) The intelligent access control system based on the sensing network is characterized in that the signal acquired by the temperature sensor is a weak voltage signal, so that the voltage V0 output by the temperature sensor is amplified by the signal amplification unit through the operational amplifier A1, the capacitors C1-C3 and the resistors R1-R7, and the signal amplification unit consisting of the operational amplifier A1, the capacitors C1-C3 and the resistors R1-R7 only has drift of 1.45 mu V/DEG C, offset within 2 mu V, 100pA bias current and noise of 2.45nV in a 0.1Hz to 10Hz broadband. The signal filtering unit uses resistors R8-R11, capacitors C4-C7 and an operational amplifier A2 to filter the amplified electric signals, so that the temperature detection accuracy is improved.

(3) The intelligent access control system based on the sensing network is characterized in that the image recognition module extracts the characteristic quantity of the received facial image information, and the characteristic quantity is the distance between the midpoint of two nasal wings and the midpoint of two eyes in the facial image, so that the facial image recognition can be quickly realized, and the image recognition efficiency is greatly improved.

Drawings

FIG. 1 is a schematic diagram of an intelligent access control system based on a sensor network according to the present invention;

fig. 2 is a circuit diagram of the signal processing circuit of the present invention.

Detailed Description

The intelligent access control system based on the sensor network of the present invention is described in detail with reference to the accompanying drawings and embodiments.

As shown in fig. 1, the intelligent access control system based on the sensor network provided by the invention comprises a central processing unit, a temperature sensor, a signal processing circuit, a fingerprint acquisition module, a camera, a first trigger module, a temperature identification module, a fingerprint identification module, a second trigger module, an image identification module, a third trigger module, a gate control module, a not gate circuit and an alarm module.

Wherein, the output end of the temperature sensor is connected with the input end of the signal processing circuit, the output end of the signal processing circuit is connected with the input end of the central processing device, the output end of the fingerprint acquisition module is connected with the input end of the central processing device, the output end of the camera is connected with the input end of the central processing device, the output end of the central processing device is connected with the input end of the temperature identification module, the output end of the temperature identification module is connected with the input end of the first trigger module, the output end of the first trigger module is connected with the input end of the fingerprint acquisition module, the output end of the central processing device is connected with the input end of the fingerprint identification module, the output end of the fingerprint identification module is connected with the input end of the second trigger module, the output end of the second trigger module is connected with the input end of the camera, the output end of the image recognition module is connected with the input end of a third trigger module, the output end of the third trigger module is connected with the input end of a gate control module, the output end of a second trigger module is connected with the input end of a non-gate circuit, the output end of the non-gate circuit is connected with the input end of an alarm module, the output end of the third trigger module is connected with the input end of the non-gate circuit, and the output end of the non-gate circuit is connected with the input end of the alarm module.

Wherein, the temperature sensor is used for collecting the temperature signal of an object to enter the door control and transmitting the collected temperature signal to the signal processing circuit, the signal processing circuit processes the received temperature signal, the signal processing circuit transmits the processed temperature signal to the central processing device, the central processing device transmits the received temperature signal to the temperature identification module, the temperature identification module stores a standard temperature range, if the temperature signal received by the temperature identification module is in the standard temperature range, the door control is considered to be a human body, the temperature identification module controls the first trigger module to transmit a first trigger signal to the fingerprint collection module, the fingerprint collection module starts to collect the fingerprint image of the person to enter the door control after receiving the first trigger signal, the fingerprint collection module transmits the collected fingerprint image to the central processing device, the central processing unit transmits the received fingerprint image to the fingerprint identification module, fingerprint information allowing entrance guard personnel is stored in the fingerprint identification module, if the fingerprint image information received by the fingerprint identification module is matched with any one of the stored fingerprint information allowing entrance guard personnel, the fingerprint identification module controls the second trigger module to send a second trigger signal to the camera, if the fingerprint image received by the fingerprint identification module is not matched with any one of the stored fingerprint information allowing entrance guard personnel, the second trigger module sends a low level signal to the NOT-gate circuit, the NOT-gate circuit changes the received low level into a high level and then transmits the high level signal to the alarm module, the alarm module starts alarm operation after receiving the high level signal, the camera is arranged above the fingerprint acquisition module, and the camera starts to acquire facial image information of the entrance guard personnel after receiving the second trigger signal, the camera transmits the collected facial image information to the central processing device, the central processing device transmits the received facial image information to the image recognition module, the standard characteristic quantity of the facial image information allowing entrance of an entrance guard is stored in the image recognition module, the image recognition module extracts the characteristic quantity of the facial image information received by the image recognition module, the standard characteristic quantity and the characteristic quantity extracted by the image recognition module are the same parameter, if the characteristic quantity extracted by the image recognition module is matched with the standard characteristic quantity stored by the image recognition module, the image recognition module controls the third trigger module to send a third trigger signal to the gate control module, the gate control module opens the gate of the entrance guard after receiving the third trigger signal, and if the characteristic quantity extracted by the image recognition module is not matched with the standard characteristic quantity stored by the image recognition module, the third trigger module sends a low level signal to the NOT-gate circuit, the NOT gate circuit changes the received low level into high level and then transmits the high level to the alarm module, and the alarm module starts alarm operation after receiving a high level signal.

Specifically, the standard temperature range is a temperature range corresponding to the temperature of the human body.

Specifically, the image recognition module stores standard characteristic quantities of facial image information of entrance guard personnel, and the standard characteristic quantities of the facial image information of the entrance guard personnel correspond to fingerprint information of the entrance guard personnel.

Specifically, if the fingerprint image information received by the fingerprint identification module is matched with any one of the stored fingerprint information of the entrance guard allowed to enter, the fingerprint identification module transmits the matched information of the entrance guard allowed to enter to the image identification module, and the image identification module acquires the standard characteristic quantity of the entrance guard allowed to enter according to the received information of the entrance guard.

In the above embodiment, the intelligent access control system based on the sensor network provided by the present invention comprises a central processing unit, a temperature sensor, a signal processing circuit, a fingerprint collecting module, a camera, a first triggering module, a temperature identifying module, a fingerprint identifying module, a second triggering module, an image identifying module, a third triggering module, a gate control module, a not gate circuit and an alarm module, wherein, the temperature sensor is used for confirming that the entrance guard is a human body, the signal processing circuit is used for improving the temperature monitoring precision, when the person who is monitored is a human body, the fingerprint acquisition module is triggered to perform fingerprint acquisition operation, when the acquired fingerprint is the fingerprint of the person who is allowed to enter the entrance guard, the camera is further triggered to perform image acquisition, and the image identification module extracts the characteristic information of the image so as to further judge whether the person who enters the entrance guard is the person who is allowed to enter the entrance guard.

Specifically, the image recognition module extracts a feature quantity of the facial image information received by the image recognition module, wherein the feature quantity is a distance between a midpoint of two nosewings and a midpoint of two eyes in the facial image.

Specifically, the method for extracting the distance between the midpoint of the two nasal wings and the midpoint of the two eyes in the facial image by the image recognition module is as follows:

s1: extracting coordinates (x) of the left eye in a face image₁，y₁) Coordinates of the right eye (x)₂，y₂) Coordinates of the left alar₃，y₃) And the coordinates (x) of the right alar₄，y₄）；

S2: calculating the coordinates (x) of the midpoints of two nasal wings₅，y₅) Wherein, in the step (A),

；

s3: the distance b between the left and right eye is determined, wherein,

；

s4: solving the equation of a straight line formed by connecting the left eye and the right eye:

；

s4: extracting the distance h between the midpoints of the two nasal wings and the midpoints of the two eyes in the face image, wherein,

。

in the above embodiment, the image recognition module extracts the feature quantity of the received facial image information, where the feature quantity is the distance between the midpoint of the two nasal wings and the midpoint of the two eyes in the facial image, so that facial image recognition can be quickly implemented, and image recognition efficiency is greatly improved.

As shown in fig. 2, the temperature sensor is used for collecting the temperature signal of the object to be entered into the door control, convert the collected temperature signal into a voltage signal V0, and transmit the voltage signal V0 to the signal processing circuit, V1 is the voltage signal processed by the signal processing circuit, the signal processing circuit includes a signal amplification unit and a signal filtering unit, the output end of the temperature sensor is connected with the input end of the signal amplification unit, the output end of the signal amplification unit is connected with the input end of the signal filtering unit, and the output end of the signal filtering unit is connected with the input end of the central processing unit.

Specifically, the signal amplification unit includes an operational amplifier A1, capacitors C1-C3, and resistors R1-R7.

Wherein, the output end of the temperature sensor is connected with one end of a resistor R1, the other end of a resistor R1 is grounded, one end of a resistor R1 is further connected with one end of a capacitor C1, one end of a resistor R3 is grounded, the other end of a resistor R3 is connected with the other end of a capacitor C1, one end of a resistor R2 is connected with the non-inverting input end of an operational amplifier A1, one end of a resistor R2 is further connected with the other end of a resistor R3, the other end of a resistor R2 is connected with a DC power supply Vcc, the V + end of an operational amplifier A1 is connected with a DC power supply Vcc, the V-end of an operational amplifier A1 is grounded, one end of a capacitor C2 is grounded, the other end of a capacitor C2 is connected with one end of a resistor 686R 9, the other end of a resistor R4 is connected with the inverting input end of an operational amplifier A1, the other end of a resistor R4 is connected with one end of a resistor R5, the other end of a resistor, the other end of the capacitor C3 is connected with one end of the resistor R6, one end of the resistor R7 is grounded, the other end of the resistor R7 is connected with the other end of the resistor R6, and the other end of the resistor R6 is connected with the input end of the signal filtering unit.

Specifically, the signal filtering unit comprises resistors R8-R11, capacitors C4-C7 and an operational amplifier A2.

Wherein, the output end of the signal amplifying unit is connected with one end of a capacitor C4, the other end of the capacitor C4 is connected with one end of a resistor R8, the other end of a resistor R8 is connected with a DC power supply Vcc, one end of a resistor R9 is grounded, the other end of a resistor R9 is connected with the other end of a capacitor C4, the other end of a resistor R9 is connected with one end of a resistor R10, one end of a resistor R10 is connected with one end of a resistor R11, the other end of a resistor R10 is connected with one end of a capacitor C5, the other end of a capacitor C5 is connected with the inverting input end of an operational amplifier A2, the other end of a capacitor C5 is further connected with the output end of an operational amplifier A2, the V + end of an operational amplifier A2 is connected with the DC power supply Vcc, the V-end of an operational amplifier A2 is grounded, one end of a capacitor C9 is grounded, the other end of a capacitor C6 is connected with the non-, one end of the capacitor C7 is connected with the output end of the operational amplifier A2, the other end of the capacitor C7 is connected with the input end of the central processing device, and the signal filtering unit transmits the voltage signal V1 to the central processing device.

In the above embodiment, the noise of the signal processing circuit is within 2.45nV, the drift is 1.45 μ V/° c, the model of the operational amplifier a1 is LT1012, and the model of the operational amplifier a2 is LT 1192.

In the signal amplifying unit, the resistance of the resistor R1 is 50 Ω, the resistance of the resistor R2 is 50 Ω, the resistance of the resistor R3 is 100 Ω, the resistance of the resistor R4 is 10 Ω, the resistance of the resistor R5 is 1k Ω, the resistance of the resistor R6 is 50 Ω, the resistance of the resistor R7 is 50 Ω, the capacitance of the capacitor C1 is 0.01 μ F, the capacitance of the capacitor C2 is 0.01 μ F, and the capacitance of the capacitor C3 is 0.1 μ F.

The signal amplifying unit is an in-phase amplifying circuit, the signal amplifying unit provided by the invention has higher input impedance, the gain of the signal amplifying unit is set by using a feedback resistor R5 and a gain resistor R4, and the signal amplifying unit comprises the following components:

；

given the circuit gain, there are:

；

in a specific test, the gain of the signal amplification unit was set to not less than 1/2 (-6 dB), and the unity gain of the operational amplifier a1 was stable.

The signal amplification unit generates a virtual ground with a pair of voltage dividing resistors R6 and R7 after the coupling capacitor C1 at the non-inverting input of the operational amplifier a1 to raise the operating point of the operational amplifier a1 between ground and the voltage of the dc power supply Vcc.

Coupling capacitors C1 and C3 are used in the signal amplification unit to isolate the front stage and the rear stage of an operational amplifier A1, the virtual ground of a gain resistor R4 and the real ground are also isolated by using a coupling capacitor C2, the coupling capacitors C1-C3 have low impedance at the working frequency, and the capacities of the coupling capacitors C1-C3 cannot be so small as to directly influence the gain of the operational amplifier A1 during specific tests.

In the signal filtering unit, the resistance of the resistor R8 is 100k Ω, the resistance of the resistor R9 is 100k Ω, the resistance of the resistor R10 is 1k Ω, the resistance of the resistor R11 is 1k Ω, the capacitance of the capacitor C4 is 1 μ F, the capacitance of the capacitor C5 is 0.002 μ F, the capacitance of the capacitor C6 is 0.001 μ F, the capacitance of the capacitor C7 is 0.01 μ F, and the capacitance of the capacitor C8 is 1 μ F

Wherein C2= C1 × 2, and has:

；

wherein f is the working frequency of the signal filtering unit.

Further, C4= C8=1000 × C6.

In the above embodiment, since the signal collected by the temperature sensor is a weak voltage signal, the signal amplification unit amplifies the voltage V0 output by the temperature sensor through the operational amplifier a1, the capacitors C1-C3 and the resistors R1-R7, and the signal amplification unit composed of the operational amplifier a1, the capacitors C1-C3 and the resistors R1-R7 has only drift of 1.45 μ V/deg.c, offset within 2 μ V, 100pA bias current and noise of 2.45nV within a wide band of 0.1Hz to 10 Hz. The signal filtering unit uses resistors R8-R11, capacitors C4-C7 and an operational amplifier A2 to filter the amplified electric signals, so that the temperature detection accuracy is improved.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and are not limited. Although the present invention has been described in detail with reference to the embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the spirit and scope of the invention as defined in the appended claims.