Intelligent constant temperature control system and method used for heart freezing ablation technique

Abstract

To provide an intelligent constant temperature control system and method used for heart freezing ablation technique.SOLUTION: With respect to the technical field of electric power systems, a system includes a microcomputer module, a power supply module, a button module, a display module, a temperature sensor module, a freezing sheet, and a heating device, and a constant temperature control system includes a microcomputer as its core. Temperature information on a cold temperature measured by a temperature probe is sent back to the microcomputer through the temperature sensor module. In a freezing mode, the measured temperature is compared with a set value first, and PID processing is executed to achieve the purpose of constant temperature control. Then a display is made on a display screen to display a temperature in a heating mode directly on the display screen. After a freezing process is completed, the mode can be switched to a heating mode with a button pressed, and a work process of the heating device is controlled to complete a process of freezing, reheating and freezing.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to the fields of medical devices and control technologies, and particularly to an intelligent constant temperature control system and method used in cardiac cryoablation technology.

Background Art

[0002] Atrial fibrillation is a complex arrhythmia that may be secondary to myocardial ischemia, structural heart disease, and other systemic diseases. The prevalence of atrial fibrillation increases significantly with age, with a 1% probability of developing atrial fibrillation at 60 years old or above and a 10% probability at 80 years old or above. The incidence of atrial fibrillation is increasing against the backdrop of the accelerating aging of society. In clinical treatment, the use of more effective and reliable treatment methods can improve the cure rate of atrial fibrillation patients.

[0003] Currently, the treatment methods for atrial fibrillation are mainly divided into drug therapy and non-drug therapy. Drug therapy is an early treatment method for atrial fibrillation patients, but drug therapy has no radical cure and a low cure rate. As non-drug therapies, there are radiofrequency ablation therapy and cryoablation. These two methods block the process of atrial fibrillation caused by abnormal discharge of atrial tissue by using physical energy (high frequency, freezing) to cause necrosis of atrial tissue. Compared with drug therapy, non-drug therapy has a better treatment effect, higher safety, higher reliability, shorter operation time, and fewer sequelae. Radiofrequency ablation therapy has achieved large-scale application in clinical practice, and its effectiveness and safety have been confirmed. In contrast, cryoablation is still a new technology in the development stage. In recent years, cryoablation has taken root in the field of arrhythmia treatment that has been dominated by radiofrequency ablation therapy for a long time. After several years of development, it has been completed and matured from theory to clinical application. From the results of large-scale clinical trials conducted overseas in recent years, the high safety and treatment effect of cryoablation have also been proven. Thus, cryoablation technology has great potential for application in the treatment of atrial fibrillation, and by further improving and enhancing the performance of cryoablation devices, the treatment effect can be made more prominent. The development of appropriate cryoablation devices can not only improve the treatment effect but also expand the scope of cryotherapy.

[0004] Currently, most of the cryoablation devices currently used clinically are imported from the United States, and Chinese cryoablation devices are still in a blank stage. American devices are also in the initial stage and have some problems in clinical applications. This is mainly reflected in the lack of an accurate temperature control function. During the operation, the temperature directly affects the effect of cryoablation treatment. If the temperature is not accurately controlled, problems such as insufficient freezing or excessive freezing will occur. When the device is used in clinical treatment, insufficient freezing will lead to an extension of the operation time and an increase in the operation risk, while excessive freezing will cause hypothermia in patients. Whether the freezing temperature is too high or too low, not only will the treatment effect be low, but it may also cause postoperative sequelae to the patient, resulting in low safety. Therefore, in the cardiac cryoablation system, the core technology is at a certain freezing temperature. In order to ensure the safety of patients during cryoablation treatment, controlling the freezing temperature constantly is an issue to be solved in existing cardiac cryoablation devices.

Summary of the Invention

Problems to be Solved by the Invention

[0005] To address the deficiencies of the prior art, the present invention provides an intelligent constant temperature control system and method used in cardiac cryoablation technology. The present invention establishes a closed-loop control system with compensation having accurate temperature acquisition. The temperature of the working area collected by the system is compared with the set temperature, processed by the PID algorithm, and further the freezing state of the system is controlled to be on and off, so as to stabilize the temperature of the working area collected by the temperature measurement element near the set temperature, realize constant temperature control, and ensure a certain freezing temperature.

Means for Solving the Problems

[0006] On the one hand, an intelligent constant temperature control system used in cardiac cryoablation technology, including a microcontroller module, a power supply module, a button module, a display module, a temperature sensor module, a freezing sheet and a heating device, The microcontroller module is the main control circuit composed of an STM32F103C8T6 development board, The power supply module is a step-down circuit from 5V to 3.3V integrated on a development board for supplying power to each module in the system, The button module is composed of switches with four 4-pin switch buttons, which are respectively connected to the PA1, PC15, PA0, and PA5 pins of the development board and are used for temperature adjustment and conversion of the system working state, The display module is an OLED display screen, and its lead-out pins OLED-SDA, OLED-SCL, GND, and VCC are respectively connected to the PA12, PA15, GND, and 3.3V power supply pins of the development board and are used to display the temperature adjustment state, The temperature sensor module is a configuration of a temperature acquisition circuit. The temperature sensor module is composed of a temperature measurement probe and a DS18B20 chip, and the lead-out GND, DQ, and VDD pins are respectively connected to the GND, PC14, and 3.3V power supply pins of the development board to collect temperature and send it back to the microcontroller for use, The drive module is a MOS trigger switch drive module, which is connected to the 5V power supply pin of the microcontroller to supply power to the microcontroller. The PWM input signal is connected to the PA6 pin of the microcontroller to control the on and off of the operation of the freezing sheet. Similarly, the input signal of the drive circuit is connected to the PB9 pin of the microcontroller to control the heating status of the heating device. The output end of the drive module is respectively connected to the heating module and the freezing module.

[0007] On the other hand, it is an intelligent constant temperature control method used in cardiac cryoablation technology, which is realized based on the intelligent constant temperature control system used in the cardiac cryoablation technology, Step 1 of turning on the power of the system and pressing the button to select the working mode of freezing or heating, Step 2 in which the microcontroller determines the pressed button through the pin input status and enters the corresponding working state, If it is in the refrigeration mode at this time, the microcontroller makes the refrigeration sheet refrigerate through the drive module. If it is in the heating mode at this time, step 3 is to make the heating device start heating. Step 4 is that the temperature measurement probe measures the temperature of the working area and sends back the temperature information to the microcontroller. It includes step 5 of comparing the measured temperature with the set value, performing PID processing to control the on and off of the refrigeration sheet, and completing the constant temperature control function.

Advantages of the Invention

[0008] Beneficial effects obtained by adopting the above technical solutions: The present invention provides an intelligent constant temperature control system and method used in cardiac cryoablation technology. Based on the problem of inaccurate temperature control in existing devices of the cardiac cryoablation system, a control method using a PID controller is proposed. This control method brings good temperature control effects to the system, improves the temperature control accuracy of the system, effectively solves the surgical risks caused by the processes of insufficient refrigeration and excessive refrigeration, and can improve the problem of inaccurate temperature control of existing devices.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5A

Figure 5B

Figure 5C

Figure 5D

Modes for Carrying Out the Invention

[0010] Specific embodiments of the present invention will be described in more detail below with reference to the drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0011] On the one hand, it is an intelligent constant temperature control system used in cardiac cryoablation technology, including a microcontroller module, a power supply module, a button module, a display module, a temperature sensor module, a cryo sheet, and a heating device. The microcontroller module is a main control circuit composed of an STM32F103C8T6 development board. The power supply module is a step-down circuit from 5V to 3.3V integrated on a development board for supplying power to each module in the system. The button module is composed of a switch with four 4-pin switch buttons, which are respectively connected to the PA1, PC15, PA0, and PA5 pins of the development board and are used for temperature adjustment and conversion of the system working state. The display module is an OLED display screen, and its lead-out pins OLED-SDA, OLED-SCL, GND, and VCC are respectively connected to the PA12, PA15, GND, and 3.3V power supply pins of the development board and are used for displaying the temperature adjustment state. The temperature sensor module is composed of a temperature acquisition circuit. The temperature sensor module is composed of a temperature measurement probe and a DS18B20 chip. The lead-out GND, DQ, and VDD pins are respectively connected to the GND, PC14, and 3.3V power supply pins of the development board to collect temperature and send it back to the microcontroller. The drive module is a high-power MOS trigger switch drive module. This drive circuit is connected to the 5V power pin of the microcontroller to supply power to the microcontroller. The PWM input signal is connected to the PA6 pin of the microcontroller to control the on and off of the operation of the refrigeration sheet. Similarly, the input signal of the drive circuit is connected to the PB9 pin of the microcontroller to control the heating status of the heating device. The output ends of the drive module are respectively connected to the heating module and the refrigeration module.

[0012] Figure 1 is a block diagram of the overall intelligent constant temperature control system according to an embodiment of the present invention. This system is a low-temperature control system with temperature measurement and display under microcontroller control. As can be seen from Figure 1, the constant temperature control system has a microcontroller as the core. The cold and hot temperatures measured by the temperature probe send back the temperature information to the microcontroller. In the refrigeration mode, first, the measured temperature is compared with the set value, and PID processing is executed to achieve the purpose of constant temperature control, and then it is displayed on the display screen. The temperature in the heating mode is directly displayed on the display screen. When the refrigeration process is completed, it can be set to switch to the heating mode by pressing a button, and the working process of the heating device is controlled to complete the process of refrigeration - reheating - refrigeration.

[0013] Figure 2 is a control principle diagram of the PID controller used in the present invention. In the case of a single PID controller used in the temperature control system, usually, r(t) is set as the reference temperature, that is, the set value that meets the requirements, and y(t) is set as the converted temperature of the sensor, that is, the measured value. The difference between the set value and the measured value becomes the control deviation of the temperature control system, that is, e(t)=r(t)-y(t). The PID controller applied to industrial control needs to comprehensively consider the basic requirements such as speed, accuracy, and stability based on the performance characteristics of the controlled object and the on-site environmental conditions. By flexibly combining the proportional, integral, and differential methods, an optimal strategy for the control target is realized. The principle of PID control can be expressed by Equation (1).

[0014]

Equation

[0015] Here, K p , T I , T D represent the proportionality constant, integral constant, and derivative constant respectively. u(t) is the control output after calculation by the PID controller, and e(t) is the actual control deviation.

[0016] With the introduction of computer technology in industrial processes, the control process has also been converted from analog PID control, and software-based PID control, i.e., digital PID control, has been realized. Digital PID control can be divided into a position type and an incremental type. The incremental type PID control algorithm is an improvement that takes the increment with respect to the position type PID and can avoid some problems existing in the position type. It has the self-adaptation of the controller: in incremental type PID control, the change in deviation only affects the increment of the control output and does not affect the gain setting of the controller itself. Therefore, when the system is disturbed or changed, the incremental type PID control can adaptively adjust the control output to achieve a better control effect. It avoids integral saturation: in incremental type PID control, only the deviation amount and the change in the deviation amount are used to calculate the increment of the control output. In contrast, in position type PID control, the integral of the deviation is required to calculate the overall control output. However, if the integral error is too large, integral saturation will occur, affecting the control effect. The present invention uses the incremental type PID algorithm to make the control temperature more accurate and achieve a better control effect.

[0017] On the other hand, it is an intelligent constant temperature control method used in cardiac cryoablation technology, which is realized based on the intelligent constant temperature control system used in the cardiac cryoablation technology. As shown in Figure 3, Step 1 of turning on the power of the system and pressing a button to select the working mode of freezing or heating; Step 2 in which the microcontroller determines the pressed button through the pin input situation and enters the corresponding working state; When it is in the refrigeration mode at this time, the microcontroller makes the refrigeration sheet refrigerate through the drive module. When it is in the heating mode at this time, step 3 is to make the heating device start heating. Step 4 is that the temperature measurement probe measures the temperature of the working area and sends back the temperature information to the microcontroller. It includes step 5 of comparing the measured temperature with the set value, performing PID processing to control the on and off of the refrigeration sheet, and completing the constant temperature control function.

[0018] Figure 4 is a schematic diagram of the system hardware designed according to the present invention. The system includes a main control module, a temperature acquisition module, a drive module, a refrigeration module, a heating module, and a human-computer interaction, and also includes a display screen and a button module. The system sends back the temperature data collected by the temperature acquisition module to the microcontroller for processing, thereby controlling to keep the temperature of the working area constant.

[0019] Figure 5A shows the main control circuit of the hardware control system of the present invention. The main control module uses an upgraded version of the STM32F103C8T6 development board and assigns the pin connection status based on comprehensive considerations such as the functional requirements of the system and the specific pin functions of the chip. Here, the display module has a 4-pin wiring. Pin PA12 is connected to the IIC bus data signal of the OLED display screen, PA15 is connected to the IIC bus clock signal of the OLED display screen, and the other two wires are respectively connected to the power ground and the power plus. The four function buttons corresponding to the button module complete the conversion of the system state and the temperature setting. The corresponding relationship of the pins is that button S1 is connected to pin PA1, button S2 is connected to pin PC15, button S3 is connected to pin PA0, and button S4 is connected to pin PA5. The input signals of the drive modules of the refrigeration device and the heating device are respectively connected to pin PA6 and pin PB9. The temperature acquisition module uses a 3-pin temperature sensor module DS18B20. In addition to the power plus and the power ground, DQ is the digital signal input / output terminal and is connected to the PC14 pin. The power supply voltages used in this system are 5V and 3.3V. According to the requirements of each power supply voltage, the corresponding power supply pins and power ground are connected.

[0020] Figure 5B shows the temperature acquisition circuit of the hardware control system of the present invention. In order to achieve constant temperature control and real-time monitoring of the operating state of the system, a temperature measuring element is used to measure the temperature of the working area, feedback it to the microcontroller in real time, compare it with the set temperature value, and through the processing of the PID algorithm, the measured value is stabilized within the allowable error range of the set value to achieve constant temperature control. The DS18B20 temperature sensor uses a temperature measurement chip with high precision, single bus, and digital output. The small size, low hardware cost, strong anti-interference ability, and high precision of the sensor are utilized. Since the DS18B20 is single-wire communication, data can only be transmitted and received via DQ. To ensure stability, it is necessary to add a pull-up resistor. In the design, a DS18B20 temperature sensor module is selected, a pluggable DS18B20 chip is mounted on the board, all three corresponding pins of the chip are drawn out, a pull-up resistor is built in to maintain stability, and when the temperature measurement is functioning, the on-board power indicator light lights up to indicate the operating state.

[0021] Figure 5C shows the drive circuit of the hardware control system of the present invention. The microcontroller controls the working states of the refrigeration device and the heating device, and adjusts the refrigeration process and drive power while considering PWM. Therefore, a high-power MOS trigger switch drive module is used. The advantage of this module is that by using dual MOS tubes in parallel to drive high power, the current can be increased, a strong output can be achieved, the power can reach 400W at room temperature, meeting the usage needs of most devices and supporting PWM signals. The working voltage is 5V - 36V, the trigger signal source is connected to the I / O port of the microcontroller, a DC power supply, etc., the frequency of the PWM signal used is set between 0 and 20KHZ, and the PWM signal input of this module can be used. The output end of this module can be used to control high-power devices. In this design, a high-power MOS trigger switch drive module is used, the power supply voltage is 5V, and this module is mainly applied to two functional modules of refrigeration and heating. On the one hand, a PWM signal is input to control the on and off status of the refrigeration device. Here, the signal frequency is 1KHZ to complete the refrigeration function. On the other hand, by pressing a button to control the input I / O port signal, the working state of the heating device is determined.

[0022] Figure 5D shows the human-computer interaction circuit of the hardware control system of the present invention. The circuit of this part includes two parts: a display module and a button module. Here, the button module can control the startup, stop, switching, etc. of devices and modules in the system according to operations, or change the parameters and states in the system. In this system, the human-computer interaction consists of a display screen and buttons. By analyzing the state of whether a button is pressed, working states, temperature values, etc. can be set. In this design, button S2 realizes the setting of the refrigeration mode and the heating mode, and S3 and S4 are used for setting the target temperature. Here, S3 adjusts the set temperature upward in the refrigeration mode, and the set temperature increases by 1°C each time it is pressed. S4 adjusts the set temperature downward, and it decreases by 1°C each time it is pressed. When S1 is pressed, the heating or refrigeration process is temporarily stopped and returns to the stopped state. The display module is a 4-pin, 0.96-inch OLED display screen that communicates in IIC mode. IIC communication is a common microcontroller communication protocol and a serial communication bus. Multiple devices can be mounted on the bus as slaves, and the host can send content to different slave devices by selecting different transmission addresses and belongs to a multi-master-slave architecture. IIC supports multiple masters. Devices connected to the bus have independent 7-bit addresses, and the host uses this address to access the slave. Here, the OLED screen of the peripheral device is used to transfer data with the microcontroller using IIC, and the corresponding slave address is 0x78. Since the pins of the hardware IIC are occupied, here, by using the software simulation method, pins can be arbitrarily assigned according to the usage of the pins, and it is also easy to transplant to other devices.

[0023] The above description is a preferred embodiment of the present disclosure and merely exemplifies the applicable technical principles. Those skilled in the art should understand that the scope of the invention related to the embodiments of the present disclosure is not limited to the technical solutions obtained from the specific combinations of the above technical features, and other technical solutions formed by any combination of the above technical features or their equivalents without departing from the above inventive concept are also within the scope. For example, technical solutions (but not limited thereto) formed by exchanging the above features with technical features having similar functions disclosed in the embodiments of the present disclosure.

Description of Reference Numerals

[0024] (a) Main control circuit, (b) Temperature acquisition circuit, (c) Drive circuit, (d) Human-computer interaction circuit

Claims

1. It includes a microcomputer module, a power module, a button module, a display module, a temperature sensor module, a freezing sheet and a heating device. The microcontroller module is a main control circuit configured by an STM32F103C8T6 development board; the power supply module is a 5V to 3.3V step-down circuit integrated in the development board; the button module is a switch with four switch buttons, which are respectively connected to the four IO pins of the development board, and are used for temperature adjustment and system working state conversion; the display module is an OLED display screen, whose read-out pins are respectively connected to the IO pin, GND, and 3.3V power pin of the development board; and the temperature sensor module is a temperature acquisition circuit configuration, whose output pins are respectively connected to the IO pin, GND, and 3.3V power pin of the development board, for collecting temperature and sending it back to the microcontroller module.

2. The intelligent constant temperature control system used in cardiac cryoablation technology as claimed in claim 1, characterized in that the driving module is a MOS trigger switch driving module, which is connected to the 5V power pin of the microcontroller to supply power to the microcontroller, the PWM input signal is connected to the PA6 pin of the microcontroller to control the on and off of the work of the freezing sheet, and the input signal of the MOS trigger switch driving module is connected to the PB9 pin of the development board to control the heating device.

3. The intelligent constant temperature control system used in cardiac cryoablation technology as claimed in claim 2, characterized in that the output ends of the driving module are connected to a heating device and a freezing sheet respectively.

4. The invention is realized based on an intelligent thermostatic control system for use in the cardiac cryoablation technique according to any one of claims 1 to 3, Step 1: turn on the system and press the button to select the working mode of freezing or heating; Step 2: the microcontroller determines which button is pressed through the pin input status and enters the corresponding working state; Step 3: if the current time is the freezing mode, the microcomputer controls the driving module to make the freezing sheet freeze, and if the current time is the heating mode, the microcomputer controls the heating device to start heating; Step 4, the temperature measurement probe measures the temperature of the working area and sends the temperature information back to the microcomputer; The intelligent constant temperature control method used in cardiac cryoablation technology includes step 5: comparing the measured temperature with the set value, and carrying out PID processing to control the freezing sheet to be on and off, thereby completing the constant temperature control function.

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