阅读说明：本技术 一种心磁测量装置自动预警防护系统 (Automatic early warning protection system of magnetocardiogram measuring device ) 是由 周向阳 戴欣平 王维乾 于 2021-08-23 设计创作，主要内容包括：本发明公开的一种心磁测量装置自动预警防护系统,解决心磁测量支撑杆与心磁测量桶口干涉而导致的心磁测量装置损坏的问题,可保证装置在测量过程中不会受到撞击的影响。本发明的系统包括上位机软件和安全预警防护电路,上位机软件通过串口通信模块将上位机端USB电平转换成为电路端TTL电平,接收电路系统传输的距离参数,设置电路系统传输数据时间以及接收数据上限,安全预警硬件电路系统包括温度补偿电路,LCD显示电路,预警电路与制动电路。可以通过在程序中设置距离值,控制报警距离长短,在心磁测量装置相撞之前,制动电路控制电机及时制动。同时通过预警电路报警,可实现在无人情况下停止测量床板,保证心磁测量装置的安全。(The automatic early warning protection system for the magnetocardiogram measuring device disclosed by the invention solves the problem that the magnetocardiogram measuring device is damaged due to the interference of the magnetocardiogram measuring support rod and the magnetocardiogram measuring barrel opening, and can ensure that the device is not influenced by impact in the measuring process. The system comprises upper computer software and a safety early warning protection circuit, wherein the upper computer software converts a USB level at an upper computer end into a TTL level at a circuit end through a serial port communication module, receives a distance parameter transmitted by the circuit system, and sets the data transmission time and the upper limit of received data of the circuit system, and the safety early warning hardware circuit system comprises a temperature compensation circuit, an LCD display circuit, an early warning circuit and a braking circuit. The alarm distance can be controlled by setting a distance value in a program, and the braking circuit controls the motor to brake in time before the magnetocardiogram measuring device collides. Meanwhile, the early warning circuit gives an alarm, so that the bed board can be stopped to be measured under the unmanned condition, and the safety of the magnetocardiogram measuring device is ensured.)

1. An automatic early warning protection system for a magnetocardiogram measuring device, comprising: the system comprises an upper computer software system and an automatic early warning protection circuit;

the upper computer software system receives and displays distance data measured by the ultrasonic ranging sensor in the automatic early warning protection circuit through the serial port communication circuit, and controls the time interval of data transmission and the upper limit of data receiving and transmission of the ultrasonic ranging sensor;

the automatic early warning protection circuit includes: the device comprises a display circuit, a braking circuit, an early warning circuit, a temperature compensation circuit, a control chip and an ultrasonic ranging sensor; when the magnetocardiogram device is used, the PLC controls the motor to drive the magnetocardiogram measuring bed plate and the magnetocardiogram measuring support rod fixed on the bed plate to move forward and backward, and the magnetocardiogram measuring support rod collides with a magnetocardiogram measuring barrel opening in the process of moving forward of the bed plate; automatic early warning protection circuit measures heart magnetism through ultrasonic ranging sensor and measures the bung hole distance with heart magnetism, and the ultrasonic signal that ultrasonic ranging sensor sent enlargies via the second grade operational amplification circuit that operational amplifier constitutes, and second grade operational amplification circuit is respectively: the first-stage integrating circuit and the second-stage inverse proportional amplifying circuit; the pins of the automatic gain module are respectively connected to an operational amplifier in the second-stage inverse proportional amplification circuit to obtain an inverse input end and an inverse output end; the automatic gain module is adjusted by the control chip, different ultrasonic waves are amplified by different times according to different distance information, and because the attenuation degrees of ultrasonic signals at different propagation distances are different, the automatic gain module effectively avoids that insufficient signal amplification is submerged by noise due to too small amplification factor or signal distortion due to too large amplification factor is finally obtained into an accurate measurement distance value by adopting different amplification factors; the measured distance value is displayed in a display circuit, and simultaneously the measured distance value is transmitted to an upper computer software system through a serial port communication circuit and displayed on an interface of the upper computer software system; by setting a distance threshold value, the length of the alarm distance is controlled according to actual use requirements, before the magnetocardiogram measuring support rod collides with the magnetocardiogram measuring barrel opening, the brake circuit timely brakes the motor so as to prevent the bed board from continuously advancing and avoid the magnetocardiogram measuring support rod fixed on the bed board from colliding with the magnetocardiogram measuring barrel opening, because the relay in the braking circuit passes large current on the contact surface inside the braking circuit during the use process, meanwhile, the armature is switched between the moving contact and the static contact, the generated arc heat can also cause the evaporation of the contact material, therefore, the contacts fail, the relay is damaged, the bed plate cannot be braked in time, and an isolation protection part is added into the braking circuit and is connected with the two ends of the relay, when the relay contact fails, the isolation protection part in the braking circuit guides the large current generated on the surface of the contact, so that the triode and the diode in the braking circuit are prevented from being damaged; meanwhile, the alarm is given through an automatic early warning protection circuit.

2. An automatic early warning protection method for a magnetocardiogram measuring device is characterized by comprising the following steps:

step 1: automatic early warning protection circuit is placed heart magnetism measuring barrel mouth department, and the ultrasonic wave that ultrasonic sensor launches wherein returns when meetting the barrier, and supersound echo signal enlargies via the second grade amplifier circuit that operational amplifier constitutes, adds the automatic gain module in the amplified constitution of operation, and second grade operational amplifier circuit is respectively: the first-stage integrating circuit and the second-stage inverse proportional amplifying circuit; pins of the automatic gain module are respectively connected to the reverse input end and the reverse output end of an operational amplifier in the second-stage reverse proportional amplification circuit; the automatic gain module is adjusted by the control chip, different ultrasonic waves are amplified by different times according to different distance information, and because the attenuation degrees of ultrasonic signals at different propagation distances are different, the signal amplification deficiency caused by over-small amplification factor is effectively prevented from being submerged by noise by adopting different amplification factors, or the signal distortion caused by over-large amplification factor is effectively avoided by adopting different amplification factors;

step 2: aiming at the problem that the ultrasonic wave is influenced and changed by temperature in the step 1, the ultrasonic wave speed is corrected by using a temperature compensation circuit, the distance measurement error caused by temperature is reduced, the processed ultrasonic echo signal is converted into a high-level signal, and according to a formula: calculating a distance value by taking s as vt, s as a distance, v as an ultrasonic speed and t as time;

and step 3: the distance value measured after temperature correction in the step 2 is displayed on a display circuit, and the distance data is displayed on an upper computer software system through a serial port communication circuit, so that the aim of remote monitoring is fulfilled;

and 4, step 4: the PLC controls the motor to control the moving forward of the magnetocardiogram measuring bed board, when the magnetocardiogram measuring support rod fixed on the bed board exceeds the magnetocardiogram measuring barrel opening and the distance value between the magnetocardiogram measuring support rod and the magnetocardiogram measuring barrel opening is smaller than the set distance threshold value, the motor is braked to prevent the bed board from moving forward continuously to avoid collision between the magnetocardiogram measuring support rod fixed on the bed board and the magnetocardiogram measuring barrel opening, and the purpose of controlling 24V large voltage by 3.3V-5V small voltage is realized by the brake circuit; when the relay contact fails, the isolation protection part in the brake circuit conducts the heavy current generated on the surface of the contact, so that the triode and the diode in the brake circuit are prevented from being damaged; meanwhile, the early warning circuit gives an alarm to automatically brake the bed plate, so that the core magnetic measurement support rod is prevented from colliding with the core magnetic measurement barrel opening, and the purpose of automatic early warning protection is achieved.

3. The automatic early warning protection method of the magnetocardiogram measuring device as claimed in claim 2, wherein: in the step 1, a second-stage operational amplification circuit is composed of an integral circuit composed of a TL082 operational amplifier and a reverse proportional amplification circuit, the second-stage amplification circuit amplifies ultrasonic echo signals, firstly, ultrasonic signals pass through the first-stage integral circuit composed of the TL082 for waveform conversion and offset voltage elimination of the amplification circuit, then pass through the second-stage reverse amplification circuit composed of the TL082, a gain module is adopted in the second-stage reverse amplification circuit, and the gain module is controlled by a control chip to amplify different ultrasonic waves by different multiples.

4. The automatic early warning protection method of the magnetocardiogram measuring device as claimed in claim 2, wherein: in the step 2, the temperature compensation circuit is composed of a DS18B20 temperature sensor, the DS18B20 has three pins in total, two of the three pins are connected to a VCC power supply terminal and a GND ground terminal of the control chip, the other pin is connected to a GPIO port of the control chip, and temperature reading and writing are realized through a single interface.

5. The automatic early warning protection method of the magnetocardiogram measuring device as claimed in claim 2, wherein: in step 3, the upper computer software system is implemented as follows:

converting the USB level of the upper computer software end into the TTL level of the automatic early warning protection hardware circuit through a CH340 USB-to-serial port chip, so that the automatic early warning protection circuit is matched with the level of an upper computer software system;

the upper computer software system comprises a port configuration module, a data sending module and a receiving and displaying module; the port configuration module searches serial port numbers and achieves the purpose of data transmission by carrying out baud rate matching with a hardware circuit; the data sending module sets the interval time for sending data, sets whether the data sending is binary or hexadecimal according to the size of the data, and empties a data sending area; and the receiving display module displays the received data.

6. The automatic early warning protection method of the magnetocardiogram measuring device as claimed in claim 2, wherein: in the step 4, the braking circuit consists of a relay, a diode, a PNP triode and a slide rheostat; the relay consists of an iron core, a coil, an armature and a contact reed; a certain voltage is applied to two ends of the coil, a certain current flows in the coil, so that an electromagnetic effect is generated, the armature iron overcomes the pulling force of the return spring under the action of electromagnetic force attraction and is attracted to the iron core, and the movable contact and the fixed contact of the armature iron are driven to be attracted; when the relay contact fails, the isolation protection part in the brake circuit conducts the heavy current generated on the surface of the contact, so that the triode and the diode in the brake circuit are prevented from being damaged; when the distance between the magnetocardiogram measuring support rod and the magnetocardiogram measuring barrel opening is smaller than a preset threshold value, the current acts on the attraction force generated between the electromagnet core and the armature of the relay, the armature of the relay is attracted to achieve a preset step change, the motor is braked in time to prevent the bed board from continuing to advance, and meanwhile, the automatic early warning protection circuit gives an alarm.

Technical Field

The invention relates to an automatic early warning protection system and method based on an extremely weak magnetocardiogram measuring device, and belongs to the technical field of automatic control which is applied to extremely weak magnetocardiogram measurement and applies a distance measuring sensor and early warning.

Background

The disease burden of cardiovascular diseases is increasing day by day and has become a major public health problem. The causes of heart disease are complex, but conventional examination often has certain difficulty in quickly and accurately determining the causes of heart disease. Conventional cardiac diagnostic means include electrocardiography, coronary angiography, color echocardiography, and flat panel experiments, among others. The traditional detection technology has the defects that the coronary angiography diagnosis has high accuracy and is a minimally invasive operation, but the cost is high, and certain trauma can be caused to a patient. However, the conventional electrocardiogram can only reflect the condition of a short time, the heart abnormality of many people is intermittent, and the abnormality is not necessarily occurred when the electrocardiogram is made, so that the electrocardiogram cannot play a screening role in the condition, and the defects of low sensitivity, low accuracy and the like exist. It follows that the conventional cardiac examination method is limited clinically. The research on heart diseases by measuring the magnetocardiogram and generating a novel nondestructive passive high-resolution magnetocardiogram by using a quantum magnetic field precision measurement method is a future development trend.

In the research aspect of ultra-high sensitive extremely-weak magnetocardiogram measurement scientific devices, experiments such as Kominis in 2003 demonstrate a multi-channel SERF magnetometer with higher sensitivity, Wyllie and the like in 2012 detect the magnetocardiogram of a pregnant woman and a fetus, Border division of university of Colorado in 2015 adopts a 25-channel SERF for measuring the magnetocardiogram of the pregnant woman and the fetus, Genetesis corporation in 2017 develops a zero-field resonance magnetometer QZFM probe based on Quspin, successfully develops novel rapid, noninvasive and accurate magnetocardiogram measurement equipment, and obtains FDA certification in 2019. In the first generation of magnetocardiogram measuring device developed by Beijing aerospace university in 2020, a multi-degree-of-freedom magnetocardiogram measuring probe box is adopted, and when the device is used, the problem of interference exists between the magnetocardiogram measuring probe box and a barrel opening, and the barrel body and the magnetocardiogram measuring probe can be damaged if not solved.

Disclosure of Invention

The invention solves the problems: the automatic early warning protection system and method for the magnetocardiogram measuring device overcome the defects of the prior art, solve the problem that the magnetocardiogram measuring device is damaged due to interference of a magnetocardiogram measuring support rod and a magnetocardiogram measuring barrel opening caused by mistaken touch of an operator or a patient in the advancing process of the magnetocardiogram measuring device, prevent the magnetocardiogram measuring device from being influenced by impact in the measuring process, and ensure that the magnetocardiogram measuring device is used in a normal state.

The technical scheme of the invention is as follows: an automatic early warning protection system for a magnetocardiogram measuring device, comprising: the system comprises upper computer software and an automatic early warning protection circuit, wherein an upper computer software system converts a USB level at an upper computer end into a TTL level at a circuit end through serial port communication, the upper computer software can receive and display distance data measured by an ultrasonic ranging sensor circuit system in the automatic early warning protection circuit through the serial port communication, and can control the time interval of data transmission and the upper limit of received data of the ultrasonic ranging sensor;

the automatic early warning protection circuit includes: the device comprises a display circuit, a braking circuit, an early warning circuit, a temperature compensation circuit, a control chip and an ultrasonic ranging sensor, wherein the control chip comprises VCC, GND and 144 GPIO ports; when the magnetocardiogram device is used, the PLC controls the motor to drive the magnetocardiogram measuring bed plate and the magnetocardiogram measuring support rod fixed on the bed plate to move forward and backward, and the magnetocardiogram measuring support rod collides with a magnetocardiogram measuring barrel opening in the process of moving forward of the bed plate; automatic early warning protection circuit measures heart magnetism through ultrasonic ranging sensor and measures the bung hole distance with heart magnetism, and the ultrasonic signal that ultrasonic ranging sensor sent enlargies via the second grade operational amplification circuit that operational amplifier constitutes, and second grade operational amplification circuit is respectively: the first stage of integrating circuit and the second stage of inverse proportional amplifying circuit. And pins of the automatic gain module are respectively connected to an operational amplifier in the second-stage inverse proportional amplification circuit to obtain an inverse input end and an inverse output end. The automatic gain module is adjusted by the control chip, different ultrasonic waves are amplified by different times according to different distance information, and because the attenuation degrees of ultrasonic signals at different propagation distances are different, the automatic gain module effectively avoids that insufficient signal amplification is submerged by noise due to too small amplification factor or signal distortion due to too large amplification factor is finally obtained into an accurate measurement distance value by adopting different amplification factors; the measured distance value is displayed in a display circuit, and simultaneously the measured distance value is transmitted to an upper computer software system through a serial port communication circuit and displayed on an interface of the upper computer software system; by setting a distance threshold, controlling the length of an alarm distance according to actual use requirements, and before a magnetocardiogram measurement support rod collides with a magnetocardiogram measurement barrel opening, a brake circuit timely brakes a motor to prevent a bed board from continuously advancing to avoid collision between the magnetocardiogram measurement support rod fixed on the bed board and the magnetocardiogram measurement barrel opening; meanwhile, the alarm is given through an automatic early warning protection circuit.

The invention discloses an automatic early warning protection method for a magnetocardiogram measuring device, which comprises the following steps:

step 1: the automatic early warning protection circuit is placed at the heart magnetism measuring barrel mouth, and the ultrasonic wave that ultrasonic sensor launches, when meetting the barrier and returning, the ultrasonic echo signal enlargies via the second grade amplifier circuit that TL082 operational amplifier constitutes, adds the automatic gain module in the amplified constitution of operation, and second grade operational amplifier circuit is respectively: the first stage of integrating circuit and the second stage of inverse proportional amplifying circuit. And pins of the automatic gain module are respectively connected to the reverse input end and the reverse output end of an operational amplifier in the second-stage reverse proportional amplifying circuit. The automatic gain module is adjusted by the control chip, different ultrasonic waves are amplified by different times according to different distance information, and because the attenuation degrees of ultrasonic signals at different propagation distances are different, the signal amplification deficiency caused by over-small amplification factor is effectively prevented from being submerged by noise by adopting different amplification factors, or the signal distortion caused by over-large amplification factor is effectively avoided by adopting different amplification factors;

step 2: aiming at the problem that the ultrasonic wave is influenced and changed by temperature in the step 1, the ultrasonic wave speed is corrected by using a temperature compensation circuit, the distance measurement error caused by temperature is reduced, the processed ultrasonic echo signal is converted into a high-level signal, and according to a formula: calculating a distance value by taking s as vt, s as a distance, v as an ultrasonic speed and t as time;

and step 3: the distance value measured after temperature correction in the step 2 is displayed on a display circuit, and the distance data is displayed on an upper computer software system through a serial port communication circuit, so that the aim of remote monitoring is fulfilled;

and 4, step 4: the PLC controls the motor to control the moving forward of the magnetocardiogram measuring bed board, when the magnetocardiogram measuring support rod fixed on the bed board exceeds the magnetocardiogram measuring barrel opening and the distance value between the magnetocardiogram measuring support rod and the magnetocardiogram measuring barrel opening is smaller than the set distance threshold value, the motor is braked to prevent the bed board from moving forward continuously to avoid collision between the magnetocardiogram measuring support rod fixed on the bed board and the magnetocardiogram measuring barrel opening, and the purpose of controlling 24V large voltage by 3.3V-5V small voltage is realized by the brake circuit; when the relay contact fails, the isolation protection part in the brake circuit conducts the heavy current generated on the surface of the contact, so that devices such as a triode, a diode and the like in the brake circuit are prevented from being damaged; meanwhile, the early warning circuit gives an alarm to automatically brake the bed plate, so that the core magnetic measurement support rod is prevented from colliding with the core magnetic measurement barrel opening, and the purpose of automatic early warning protection is achieved.

The second-stage operational amplifier circuit in the step 1 is realized as follows:

the ultrasonic echo signal is amplified by a secondary amplification circuit consisting of an integral circuit formed by a TL082 operational amplifier and a reverse proportional amplification circuit, firstly, the ultrasonic signal passes through the integral circuit formed by the TL082 in the first stage for waveform conversion and offset voltage elimination of the amplification circuit, and then passes through the reverse proportional amplification circuit formed by the TL082 in the second stage, and pins of an automatic gain module are respectively connected to a reverse input end and a reverse output end of the operational amplifier in the second stage reverse proportional amplification circuit. The automatic gain module is adjusted by control chip, carries out different multiples according to the distance information of difference and enlargies to different ultrasonic waves, because ultrasonic signal is different at the propagation distance attenuation degree of difference, is different from the amplifier circuit among traditional ultrasonic ranging sensor, adopts different magnification effectively to avoid because of the signal amplification that the magnification undersize leads to is not enough submerged by the noise, perhaps the signal distortion that the magnification too big leads to reduces the problem of range finding error.

The temperature compensation circuit in the step 2 is realized as follows:

step (21), the temperature and the ultrasonic wave speed have the following relationship according to the prior art:

v＝331.45+0.607T

every time the temperature changes by 1 ℃, the ultrasonic wave speed changes by 0.6m/s, so the influence of the temperature is not negligible, a temperature sensor is needed to monitor the temperature in the environment, a temperature compensation circuit is designed, and the distance measurement error caused by the ultrasonic wave speed change caused by the temperature change is corrected;

and (22) the temperature compensation circuit consists of a DS18B20 temperature sensor, the DS18B20 has three pins in total, two of the three pins are connected with a VCC power supply end and a GND grounding end of the control chip, the other pin is connected with a GPIO port of the control chip, and temperature reading and writing are realized through a single interface. And (5) obtaining the actual sound speed according to the formula in the step (21).

In step 3, the upper computer software system is implemented as follows:

converting the USB level of the upper computer software end into the TTL level of the automatic early warning protection hardware circuit through a CH340 USB-to-serial port chip, so that the automatic early warning protection circuit is matched with the level of an upper computer software system;

the upper computer software system comprises a port configuration module, a data sending module and a receiving and displaying module; the port configuration module searches serial port numbers and achieves the purpose of data transmission by carrying out baud rate matching with a hardware circuit; the data sending module sets the interval time for sending data, sets whether the data sending is binary or hexadecimal according to the size of the data, and empties a data sending area; and the receiving display module displays the received data.

In the step 4: the braking circuit consists of a relay, a diode, a PNP triode and a slide rheostat; the relay consists of an iron core, a coil, an armature and a contact reed; a certain voltage is applied to two ends of the coil, a certain current flows in the coil, so that an electromagnetic effect is generated, the armature iron overcomes the pulling force of the return spring and is attracted to the iron core under the attraction effect of the electromagnetic force, and the movable contact and the fixed contact of the armature iron are driven to be attracted. Because the relay is in the use, inside contact surface passes through the heavy current, and simultaneously, armature switches between the sound contact, produces the arc heat and also can lead to the evaporation of contact material to the contact is invalid, leads to the relay to damage unable timely brake bed board and adds the isolation protection part for this reason in the braking circuit, and when the relay contact became invalid, isolation protection part in the braking circuit was with the heavy current drainage that the contact surface produced, prevents that triode, diode device in the braking circuit from being damaged. One end of the triode is connected with the VCC end of the control chip, the other end of the triode is connected with the relay, the relay is attracted when the triode is switched on, and the relay is released when the triode is switched off; the sliding rheostat is used for attracting and releasing the switch control relay, one end of the sliding rheostat as a current limiting resistor is connected with a GPIO port of the control chip, and the other end of the sliding rheostat as a current limiting resistor is connected with the triode as a current limiting resistor; when the distance between the magnetocardiogram measuring support rod and the magnetocardiogram measuring barrel opening is smaller than a preset threshold value, the triode is conducted, the current acts on the attraction force generated between the electromagnet core and the armature of the relay, the armature of the relay is attracted to achieve a preset step change, the motor is braked in time to prevent the bed board from continuing to advance, and meanwhile, the automatic early warning protection circuit gives an alarm.

Compared with the prior art, the invention has the advantages that:

(1) different from the traditional circuit for amplifying the ultrasonic echo, the invention adopts a secondary echo amplifying circuit formed by a TL082 operational amplifier to amplify the ultrasonic echo, uses a secondary amplifying circuit formed by an integrating circuit and a reverse proportion amplifying circuit to amplify the ultrasonic echo signal, and the second-stage direction proportional amplifying circuit uses an automatic gain module, pins of the gain module are connected with the inverted input end and the inverted output end of an operational amplifier in the second-stage inverting proportional amplifying circuit, can adjust the gain module by control chip according to the decay of sound wave on different distances and carry out the enlargies of different multiples to the ultrasonic wave, adopt different magnification effectively to avoid being drowned by the noise because of the signal amplification that the magnification undersize leads to, perhaps the signal distortion that the magnification too big leads to reduces the problem of range finding error.

(2) The upper computer software system comprises a plurality of modules such as a port configuration module, a data sending module and a receiving display module, can realize communication between an automatic early warning protection circuit and a software upper computer, and is convenient for remote monitoring of users.

(3) In order to realize the rotation and stop of the automatic control motor, a braking circuit needs to be designed, because a relay in the braking circuit passes through large current on the surface of an internal contact in the using process, meanwhile, the armature is switched between a moving contact and a static contact, the generated arc heat can also cause the evaporation of the contact material, thereby the contact fails, the damage of the relay can not be timely realized, an isolation protection part is added in the braking circuit for the purpose, when the contact of the relay fails, the isolation protection part in the braking circuit guides the large current generated on the surface of the contact, and devices such as a triode, a diode and the like in the braking circuit are prevented from being damaged.

Drawings

FIG. 1 is a block diagram of an automatic early warning and protection system of a magnetocardiogram measuring device according to the present invention;

FIG. 2 is a schematic circuit diagram of an automatic early warning protection system of a magnetocardiogram measuring device according to the present invention;

FIG. 3 is a two-stage amplification circuit for an ultrasonic signal;

FIG. 4 is a diagram of the upper computer software system receiving the measured data of the automatic early warning protection circuit;

FIG. 5 is a diagram of the internal structure of the DS18B20 sensor.

Detailed Description

The invention is further described with reference to the following figures and detailed description.

As shown in fig. 1, when the motor drives the magnetocardiogram measurement supporting rod to advance, if the operating personnel touches the magnetocardiogram measurement supporting rod by mistake or the patient carries out magnetocardiogram measurement, the patient accidentally touches the magnetocardiogram measurement supporting rod, the magnetocardiogram measurement supporting rod exceeds the magnetocardiogram measurement barrel opening, if the motor is not braked in time, the magnetocardiogram measurement supporting rod collides with the magnetocardiogram measurement barrel opening, huge economic loss is caused, and certain influence is generated on measurement and research of follow-up magnetocardiogram. The invention solves the technical problems and adopts the technical scheme that the design of an automatic early warning protection system of a magnetocardiogram measuring device is adopted. Fig. 1 is a structural diagram of a system, including an automatic early warning protection circuit and an upper computer software system.

As shown in fig. 2, the hardware of the automatic early warning protection circuit includes a control chip 1, a display circuit 2, a brake circuit 3, an early warning circuit 4, and a temperature compensation circuit 5. Display circuit 2, brake circuit 3, early warning circuit 4, temperature compensating circuit 5 is connected respectively on control chip 1, temperature compensating circuit 5 is through measuring ambient temperature, the correction is because of the ultrasonic wave speed of temperature influence change, display circuit 2 shows the distance between magnetocardiogram measurement bracing piece and the magnetocardiogram measurement bung hole under control chip 1's effect, when the distance value is less than the distance threshold value of settlement, brake circuit 3 brake motor under control chip 1 effect, prevent the bed board to continue to advance, alarm circuit 4 reports to the police simultaneously.

Fig. 3 is a two-stage amplification circuit of an ultrasonic signal, which is integrated on an ultrasonic distance measuring sensor, and the specific implementation method is as follows:

1. when the motor drives the magnetocardiogram measurement supporting rod to move forward, if the magnetocardiogram measurement supporting rod exceeds a magnetocardiogram measurement barrel opening, the magnetocardiogram measurement supporting rod can be detected by ultrasonic signals sent by the ultrasonic ranging sensor, the ultrasonic signals need to be amplified in order to more accurately obtain a distance value, a secondary operational amplification circuit is designed, the secondary operational amplification circuit consists of an electrostatic protection diode PESD15VL1BA, a switch diode BAV100, a capacitor, a resistor, an inductor and a TL082 operational amplifier, and is mainly divided into the following 2 parts:

(11) after the ultrasonic signal returns when encountering an obstacle, the noise in the ultrasonic signal is filtered by a low-pass filter and a high-pass filter which are formed by a resistor and a capacitor in a secondary operational amplification circuit, and the frequency noise beyond 40kHz is filtered to the maximum extent;

(12) then the ultrasonic signal is amplified by a second-stage amplifying circuit consisting of an integrating circuit consisting of a TL082 operational amplifier and a reverse proportional amplifying circuit, firstly the ultrasonic signal passes through the first-stage integrating circuit consisting of the TL082 for waveform conversion and elimination of offset voltage of the amplifying circuit, and then passes through the second-stage inverting amplifying circuit consisting of the TL082, and pins of a gain module in the second-stage inverting amplifying circuit are respectively connected to a reverse input end and a reverse output end of the operational amplifier in the second-stage inverting proportional amplifying circuit. The automatic gain module is adjusted by the control chip, and different ultrasonic waves are amplified by different times according to different distance information.

2. In order to obtain the distance between the magnetocardiogram measuring support rod and the magnetocardiogram measuring bucket opening, an ultrasonic signal needs to be calculated to obtain a distance value, but since the ultrasonic wave speed is changed under the influence of temperature, a temperature compensation circuit is adopted to correct the ultrasonic wave speed, and the method is divided into the following 2 parts:

(21) according to the prior art, the temperature and the ultrasonic wave speed have the following relationship:

v＝331.45+0.607T

v is the ultrasonic velocity and T is the time. Every time the temperature changes by 1 ℃, the ultrasonic wave speed changes by 0.6m/s, so the influence of the temperature is not negligible, a temperature sensor is needed to monitor the temperature in the environment in order to obtain the accurate ultrasonic wave speed, and then the accurate ultrasonic wave speed is obtained by using the formula;

(22) the temperature compensation circuit is composed of a DS18B20 temperature sensor, is different from a traditional thermistor temperature sensor, the DS18B20 can directly read out a temperature value, the use is convenient, and the DS18B20 is composed of a low-temperature coefficient crystal oscillator, a high-temperature coefficient crystal oscillator, a subtraction counter and a temperature register according to the graph shown in FIG. 5. The oscillation frequency of the low temperature coefficient crystal oscillator is slightly influenced by temperature, the low temperature coefficient crystal oscillator is used for generating a pulse signal with fixed frequency and sending the pulse signal to a subtraction counter 1, the oscillation frequency of the high temperature coefficient crystal oscillator is obviously changed along with the change of the temperature, the generated signal is used as the pulse input of the subtraction counter 2, the subtraction counter 1 performs subtraction counting on the pulse signal generated by the low temperature coefficient crystal oscillator, when the preset value of the subtraction counter 1 is reduced to 0, the value of a temperature register is increased by 1, the preset of the subtraction counter 1 is reloaded, the subtraction counter 1 restarts to count the pulse signal generated by the low temperature coefficient crystal oscillator, the process is circulated until the subtraction counter 2 counts to 0, the accumulation of the value of the temperature register is stopped, and at the moment, the value in the temperature register is the measured temperature. The DS18B20 has three pins in total, wherein two pins are connected with a VCC power supply end and a GND grounding end of the control chip, the other pin is connected with a GPIO port of the control chip, and the reading and the writing of the temperature are realized through a single interface. After obtaining accurate temperature measurement values, the ultrasonic wave speed under the condition of no temperature is obtained according to the formula of v being 331.45+0.607T, and then the distance value is obtained according to the formula of s being vt. Where v is the ultrasonic velocity, t is the time and s is the distance.

3. The method is characterized in that serial port communication is used for transmitting the distance value to an upper computer software system of a computer end, so that remote monitoring of users is realized, and the realization method is divided into the following 2 parts:

(31) firstly, converting a USB level of an upper computer software system end into a TTL level of an automatic early warning protection hardware circuit end through a CH340 USB-to-serial port chip, and enabling an automatic early warning protection circuit to be matched with the level of the upper computer software system;

(32) the upper computer software system comprises a port configuration module, a data sending module and a receiving and displaying module; after the automatic early warning protection circuit is matched with the level of an upper computer software system, a serial port number is searched in a port configuration module, and the purpose of data transmission is achieved after baud rate matching with a hardware circuit; setting the interval time for transmitting data through a data transmitting module, setting whether the data is transmitted in a binary system or a hexadecimal system according to the size of the data, and emptying a data transmitting area; and the receiving display module displays the received data. The distance data is displayed through the software system of the upper computer, so that a user can conveniently and remotely monitor the distance between the magnetocardiogram measuring support rod and the magnetocardiogram measuring barrel opening.

4. In order to prevent the magnetocardiogram measuring support rod from colliding with the magnetocardiogram measuring barrel opening, a braking circuit needs to be designed, and a braking motor is used for preventing the bed board from continuously advancing and is mainly divided into the following 2 parts:

(41) for the in and out of a bed board, a mode of controlling a motor by a PLC is adopted, the control voltage used by the PLC is 24V direct current, a hardware circuit of the automatic early warning protection system adopts 3.3V-5V power supply, and the PLC brake motor can be controlled by the hardware circuit only if the voltage matching of a PLC control end and the hardware circuit end of the automatic early warning protection system is realized;

(42) in order to realize voltage matching and automatically control the stop of the motor through a hardware circuit, a braking circuit is designed, and the braking circuit consists of a relay, a diode, a PNP triode and a slide rheostat. Relays are generally composed of an iron core, a coil, an armature, a contact spring, and the like. As long as a certain voltage is applied to the two ends of the coil, a certain current flows in the coil, so that an electromagnetic effect is generated, the armature iron overcomes the pulling force of the return spring and is attracted to the iron core under the attraction effect of the electromagnetic force, and the movable contact and the fixed contact of the armature iron are driven to be attracted. When the coil is powered off, the electromagnetic attraction force disappears, the armature returns to the original position under the counterforce of the spring, the movable contact and the original fixed contact are released, and the attraction and release achieve the purposes of conduction and cut-off in the brake circuit. One end of the PNP triode is connected with the VCC end of the control chip, the other end of the PNP triode is connected with the relay, the relay is attracted when the triode is switched on, and the relay is released when the triode is switched off. The switch is used for controlling the attraction and the release of the relay. One end of the slide rheostat as a current limiting resistor is connected with a GPIO port of the control chip, and the other end of the slide rheostat is connected with the triode as a current limiting resistor. Because the relay is in the use, inside contact surface passes through the heavy current, and simultaneously, armature switches between the sound contact, produces the arc heat and also can lead to the evaporation of contact material to the contact is invalid, leads to the relay to damage unable timely brake bed board and adds the isolation protection part for this reason in the braking circuit, and when the relay contact became invalid, isolation protection part in the braking circuit was with the heavy current drainage that the contact surface produced, prevents that triode, diode device in the braking circuit from being damaged. When the measured distance value is smaller than the preset threshold value, the triode in the braking circuit is conducted, the current generates attraction between the electromagnet core and the armature of the relay, and the armature of the relay is attracted to achieve the preset step change. The motor is braked in time so as to prevent the bed board from continuing to advance, on one hand, 24V large voltage at the motor end is controlled through 3.3V-5V small voltage, and on the other hand, the rotation and the stop of the motor can be automatically controlled by controlling the attraction of the armature of the relay.

Those skilled in the art will appreciate that the invention may be practiced without these specific details.