A high-precision detection system and method for the output gas flow rate of an insufflator

Abstract

The present invention discloses a high-precision detection method and system for the output gas flow rate of an insufflator, comprising: detecting the air pressure at the front and rear ends of a proportional valve, converting the obtained air pressures into electrical signals, and simultaneously feeding the electrical signals into a differential amplifier module; the differential amplifier module obtains the difference between the two based on the received electrical signals, amplifies the difference, and outputs it; a programmable amplifier performs secondary amplification to obtain a secondary amplified difference; an ADC module collects the secondary amplified difference to obtain a sampling signal, and quantizes the sampling signal under the control of an MCU module to obtain quantized data; the MCU module reads the quantized data and, based on the read quantized data, obtains the air pressure difference between the front and rear ends of a first gas pressure sensor and a second gas pressure sensor, and obtains the gas flow rate based on the air pressure difference. The present invention is used to solve the technical problem of low detection accuracy of the output gas flow rate of an insufflator, thereby achieving the purpose of improving the detection accuracy of the gas flow rate of an insufflator.

Description

Technical Field

[0001] The present invention relates to the technical field of medical insufflators, and in particular to a high-precision detection system and method for the output gas flow rate of an insufflator. Background Art

[0002] The gas flow rate detection accuracy of medical insufflators currently on the market is generally: when the actual flow rate is less than 10L / min, the error range is ±2L / min; when the actual flow rate is ≥10L / min, the error range is ±20%. This shows that there is a large error range in the current detection of gas flow rate for medical insufflators.

[0003] The wide error range in gas flow rate detection by insufflators leads to inaccurate control of the gas flow rate used to inflate the abdominal cavity during surgery. This, in turn, can lead to unstable abdominal pressure during surgery using an insufflator. This problem is particularly prominent during surgery on infants and children. Children have smaller abdominal cavities, so setting gas flow rates below 10 L / min during surgery increases the relative error, leading to greater fluctuations in abdominal pressure. Excessive fluctuations in abdominal pressure during surgery can potentially lead to medical accidents.

[0004] Since the gas flow rate through the proportional valve of the pneumoperitoneum machine is proportional to the air pressure before and after the proportional valve, the current gas flow rate detection method basically detects the air pressure at the front end of the proportional valve and the air pressure at the rear end of the proportional valve separately, then subtracts the air pressure at the front end of the proportional valve from the air pressure at the rear end of the proportional valve and calculates the gas flow rate through some operations. The two pressure sensors at the front and rear ends of the proportional valve convert the flow rate information into voltage information, which is then sent to two signal processing networks for signal processing. Finally, the MCU module samples the output voltage information of the two signal processing networks through the ADC module, subtracts them, and calculates the pressure difference of the gas before and after the proportional valve. In this method, the electrical signals generated by the two flow rates will encounter the following problems during the signal processing process:

[0005] (1) The two signal processing networks are different. For example, the electronic components, reference power supply, operational amplifier offset voltage, bias current, open-loop gain, resistance and capacitance values ​​are all different. Therefore, the amplification ratio of the two signal processing networks cannot be exactly the same.

[0006] (2) It is also difficult for the ADC module to sample the two signals synchronously, so the two sample values ​​used in subtraction are not from the same time;

[0007] (3) When the gas flow rate is small, the quantization error of the ADC is close to the signal itself, and the quantization error makes it impossible to measure the small gas flow rate with high accuracy.

[0008] The above three points determine that the measurement error of the pressure difference between the front and rear ends of the proportional valve is large, which leads to low detection accuracy of the gas flow rate output by the pneumoperitoneum machine. When the gas flow rate is small and the pressure difference between the front and rear ends of the proportional valve is small, the measurement error of the pressure difference will increase further, thereby further reducing the detection accuracy of the gas flow rate. Summary of the Invention

[0009] In order to overcome the shortcomings of the existing technology, the present invention provides a high-precision detection system and method for the output gas flow rate of the insufflator, which is used to solve the technical problem of low detection accuracy of the output gas flow rate of the insufflator, thereby achieving the purpose of improving the detection accuracy of the gas flow rate of the insufflator.

[0010] In order to solve the above problems, the technical solutions adopted by the present invention are as follows:

[0011] A high-precision detection method for the output gas flow rate of an insufflator comprises the following steps:

[0012] Detecting the air pressure at the front end and the rear end of the proportional valve using a first gas pressure sensor and a second gas pressure sensor, converting the acquired air pressure into a first electrical signal and a second electrical signal, respectively, and simultaneously sending the first electrical signal and the second electrical signal to a differential amplifier module;

[0013] The differential amplification module obtains a difference between the first electrical signal and the second electrical signal received, amplifies the difference, and outputs the amplified difference to a programmable amplifier;

[0014] After receiving the amplified difference, the programmable amplifier performs secondary amplification to obtain a secondary amplified difference;

[0015] The ADC module collects the secondary amplified difference to obtain a sampling signal, and quantizes the sampling signal under the control of the MCU module to obtain quantized data;

[0016] The MCU module reads the quantitative data, obtains the pressure difference between the front and rear ends of the first gas pressure sensor and the second gas pressure sensor according to the read quantitative data, and obtains the gas flow rate according to the pressure difference.

[0017] As a preferred embodiment of the present invention, when the ADC module collects the secondary amplified difference, it includes:

[0018] Performing anti-interference processing on the secondary amplified difference using a low-pass filter;

[0019] The ADC module collects the secondary amplified difference after anti-interference processing to obtain a sampling signal.

[0020] As a preferred embodiment of the present invention, when performing secondary amplification, it includes:

[0021] The MCU module reads the sampling signal collected by the ADC module and determines whether the size of the sampling signal is within the optimal sampling range of the ADC module;

[0022] If not, the MCU module adjusts the gain of the programmable amplifier according to the magnitude of the sampling signal until the magnitude of the sampling signal reaches the optimal sampling range of the ADC module;

[0023] Among them, when the size of the sampling signal is 3 / 4 of the range of the ADC module, it is the optimal sampling range.

[0024] As a preferred embodiment of the present invention, the process of obtaining the gas flow rate according to the pressure difference is specifically shown in Formula 1, Formula 2 and Formula 3:

[0025]

[0026]

[0027]

[0028] Where q f is the gas flow rate, in m 3 / s, Δp is the pressure difference, ρ1 is the gas density, ε is the expansion coefficient, d is the inner diameter of the proportional valve, and D is the inner diameter of the pipe upstream of the proportional valve.

[0029] As a preferred embodiment of the present invention, when the MCU module reads the quantized data, it includes:

[0030] It is determined whether the read quantized data has reached 128. If so, the reading of the quantized data is stopped.

[0031] As a preferred embodiment of the present invention, when obtaining the pressure difference between the front and rear ends of the first gas pressure sensor and the second gas pressure sensor, the method includes:

[0032] The MCU module passes the read quantized data through Kalman filtering to improve stability and accuracy.

[0033] A high-precision detection system for the output gas flow rate of an insufflator, comprising:

[0034] The first gas pressure sensor and the second gas pressure sensor are used to detect the air pressure at the front end and the rear end of the proportional valve, convert the acquired air pressure into a first electrical signal and a second electrical signal respectively, and simultaneously send the first electrical signal and the second electrical signal to the differential amplifier module;

[0035] a differential amplification module, configured to obtain a difference between the first electrical signal and the second electrical signal, amplify the difference, and output the amplified difference;

[0036] a programmable amplifier, configured to perform secondary amplification after receiving the amplified difference value to obtain a secondary amplified difference value;

[0037] An ADC module is used to collect the secondary amplified difference to obtain a sampling signal, and quantize the sampling signal under the control of the MCU module to obtain quantized data;

[0038] The MCU module is used to read the quantitative data, obtain the pressure difference between the front and rear ends of the first gas pressure sensor and the second gas pressure sensor according to the read quantitative data, and obtain the gas flow rate according to the pressure difference.

[0039] As a preferred embodiment of the present invention, the differential amplification module is a differential operational amplifier.

[0040] As a preferred embodiment of the present invention, it further includes: a low-pass filter, which is used to perform anti-interference processing on the secondary amplified difference to obtain the secondary amplified difference after anti-interference processing, and is collected by the ADC module.

[0041] As a preferred embodiment of the present invention, the low-pass filter is a Sallen-Key low-pass filter.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] (1) The present invention can effectively improve the detection accuracy of the gas flow rate output by the insufflator, especially when the gas flow rate is small and the pressure difference between the front and rear ends of the proportional valve is small;

[0044] (2) The present invention improves the accuracy and stability of abdominal cavity air pressure during surgery;

[0045] (3) Using the system and method provided by the present invention does not require any additional cost compared to the prior art;

[0046] (4) The present invention can effectively avoid medical accidents caused by excessive fluctuations in abdominal cavity air pressure during surgery.

[0047] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 - is a step diagram of a high-precision detection method for the output gas flow rate of an insufflator according to an embodiment of the present invention;

[0049] Figure 2- is a flowchart of a high-precision detection process of the gas flow rate output by the insufflator according to an embodiment of the present invention;

[0050] Figure 3 - is a diagram of a high-precision detection system for the output gas flow rate of the pneumoperitoneum machine according to an embodiment of the present invention.

[0051] Explanation of the accompanying figures: 1. Proportional valve; 2. First gas pressure sensor; 3. Second gas pressure sensor; 4. Differential amplifier module; 5. Programmable amplifier; 6. Low-pass filter; 7. ADC module; 8. MCU module. DETAILED DESCRIPTION

[0052] The present invention provides a high-precision detection method for the output gas flow rate of the pneumoperitoneum machine, such as Figure 1 and Figure 3 As shown, the following steps are included:

[0053] Step S1: Detecting the air pressure at the front end and the rear end of the proportional valve 1 by the first gas pressure sensor 2 and the second gas pressure sensor 3, converting the acquired air pressure into a first electrical signal and a second electrical signal respectively, and simultaneously sending the first electrical signal and the second electrical signal to the differential amplifier module 4;

[0054] Step S2: the differential amplifier module 4 obtains a difference between the first electrical signal and the second electrical signal according to the received signal, amplifies the difference, and outputs the amplified difference to the programmable amplifier 5;

[0055] Step S3: After receiving the amplified difference, the programmable amplifier 5 performs secondary amplification to obtain a secondary amplified difference;

[0056] Step S4: the ADC module 7 collects the secondary amplified difference to obtain a sampling signal, and quantizes the sampling signal under the control of the MCU module 8 to obtain quantized data;

[0057] Step S5: The MCU module 8 reads the quantitative data, and obtains the pressure difference between the front and rear ends of the first gas pressure sensor 2 and the second gas pressure sensor 3 according to the read quantitative data, and obtains the gas flow rate according to the pressure difference.

[0058] The method provided by the present invention eliminates measurement errors caused by hardware differences by inputting two sensor signals into a signal processing network with differential amplification characteristics for signal processing, while greatly improving the quantization level of the sampling signal, thereby achieving the purpose of improving the accuracy of detecting the output gas flow rate, especially when the gas flow rate is small and the pressure difference between the front and rear ends of the proportional valve 1 is small.

[0059] In the above step S4, when the ADC module 7 collects the secondary amplified difference, it includes:

[0060] The low-pass filter 6 is used to perform anti-interference processing on the secondary amplified difference;

[0061] The ADC module 7 collects the secondary amplified difference after anti-interference processing to obtain a sampling signal.

[0062] Specifically, a low-pass filter 6 is added before the ADC module 7 to perform anti-interference processing on the signal, thereby enhancing the anti-interference capability of the signal.

[0063] The low-pass filter 6 is a filter circuit composed of a capacitor, an inductor, and a resistor. The low-pass filter 6 can effectively filter out a specific frequency point in the power line or frequencies other than the specific frequency point, thereby obtaining a power signal of a specific frequency or a power signal after eliminating a specific frequency.

[0064] The low-pass filter 6 has the following advantages:

[0065] (1) Separate useful signals from noise to improve the signal's anti-interference ability and signal-to-noise ratio;

[0066] (2) Filter out frequency components that are not of interest to improve analysis accuracy;

[0067] (3) Separate a single frequency component from complex frequency components.

[0068] In the above step S3, when performing secondary amplification, it includes:

[0069] The MCU module 8 reads the sampling signal collected by the ADC module and determines whether the size of the sampling signal is within the optimal sampling range of the ADC module 7;

[0070] If not, the MCU module 8 adjusts the gain of the programmable amplifier 5 according to the size of the sampling signal until the size of the sampling signal reaches the optimal sampling range of the ADC module 7;

[0071] Among them, when the size of the sampling signal is 3 / 4 of the range of the ADC module 7, it is the optimal sampling range.

[0072] The ADC module 7 is called analog / digital converter in Chinese, which is a 12-bit successive approximation analog-to-digital converter and is generally used for sampling numerical values.

[0073] In the above step S3, the programmable amplifier 5 (PGA) is a highly versatile amplifier, and its amplification factor can be controlled by a program as needed.

[0074] The programmable amplifier 5 includes a fully balanced differential amplifier module, a decoder module, and a resistor switch array module. The resistance ratio of the negative feedback resistor divider in the fully balanced differential amplifier module determines the maximum gain of the amplifier. The decoding result of the decoder module controls the attenuation of the input signal by the resistor switch array module, ultimately achieving programmable gain of the amplifier.

[0075] The programmable amplifier 5 (PGA) has the following advantages: simple structure, stable bandwidth and constant input resistance, forming a constant load effect on the previous stage, and no buffer circuit is required between the amplifier and the previous stage for isolation.

[0076] In the above step S5, the process of obtaining the gas flow rate according to the pressure difference is specifically shown in Formula 1, Formula 2 and Formula 3:

[0077]

[0078]

[0079]

[0080] Where q f is the gas flow rate, in m 3 / s, Δp is the pressure difference, ρ1 is the gas density, ε is the expansion coefficient, d is the inner diameter of the proportional valve, and D is the inner diameter of the pipe upstream of the proportional valve.

[0081] Specifically, when the structure of the proportional valve 1 is determined, the gas is determined, and the temperature is determined, k in formula 1 is a constant, and the gas density ρ1 is also a constant. At this time, as long as the pressure difference before and after the proportional valve 1 is measured, the gas flow rate q can be calculated. f .

[0082] In the above step S5, when the MCU module 8 reads the quantized data, it includes:

[0083] It is determined whether the read quantized data reaches 128. If so, the reading of the quantized data is stopped. 128 data are read to facilitate Kalman filtering.

[0084] In the above step S5, when obtaining the pressure difference between the front and rear ends of the first gas pressure sensor 2 and the second gas pressure sensor 3, the following steps are included:

[0085] The MCU module 8 passes the read quantized data through Kalman filtering to improve stability and accuracy.

[0086] The MCU module 8, also known as a single-chip microcomputer or single-chip microcomputer, reduces the frequency and specifications of the central processing unit (CPU) and integrates memory, timers, USB, A / D converters, UART, PLC, DMA and other peripheral interfaces, as well as LCD driver circuits, on a single chip, forming a chip-level computer that can provide different control combinations for different applications.

[0087] The present invention provides a high-precision detection system for the output gas flow rate of the insufflator, such as Figure 2 As shown, including:

[0088] The first gas pressure sensor 2 and the second gas pressure sensor 3 are used to detect the air pressure at the front end and the rear end of the proportional valve 1, convert the acquired air pressure into a first electrical signal and a second electrical signal respectively, and simultaneously send the first electrical signal and the second electrical signal to the differential amplifier module 4;

[0089] The differential amplifier module 4 is used to obtain the difference between the first electrical signal and the second electrical signal, amplify the difference, and output the amplified difference;

[0090] The programmable amplifier 5 is used to perform secondary amplification after receiving the amplified difference value to obtain a secondary amplified difference value;

[0091] The ADC module 7 is used to collect the secondary amplified difference to obtain a sampling signal, and quantize the sampling signal under the control of the MCU module 8 to obtain quantized data;

[0092] The MCU module 8 is used to read the quantitative data, and obtain the pressure difference between the front and rear ends of the first gas pressure sensor 2 and the second gas pressure sensor 3 according to the read quantitative data, and obtain the gas flow rate according to the pressure difference.

[0093] Furthermore, the differential amplification module 4 is a differential operational amplifier.

[0094] Differential op amps have the following advantages:

[0095] (1) Enhanced noise resistance. In a differential system, ensuring that the differential transmission lines are as close as possible can make the line-coupled noise appear as a common-mode voltage. At the same time, the noise introduced by the power supply is also manifested in the form of a common-mode voltage. The differential operational amplifier has a good common-mode rejection ratio and has a good inhibitory effect on the common-mode voltage, so the differential operational amplifier has better noise resistance.

[0096] (2) The dynamic range is doubled. Due to the change in phase between the two differential outputs, the dynamic range of the output is doubled compared to the single-ended output.

[0097] (3)Eliminating even harmonics.

[0098] Furthermore, the detection system further includes: a low-pass filter 6 for performing anti-interference processing on the secondary amplified difference to obtain the secondary amplified difference after anti-interference processing, and the secondary amplified difference is collected by the ADC module 7 .

[0099] Furthermore, the low-pass filter 6 is a second-order low-pass filter.

[0100] Furthermore, low-pass filter 6 is a Sallen-Key low-pass filter. The circuit prototype of the Sallen-Key low-pass filter is constructed using a voltage feedback operational amplifier and RC elements. The advantages are simple circuit structure, concise expressions for passband gain, pole angular frequency, and quality factor, and easy adjustment of the quality factor over a wide adjustable range.

[0101] Compared with the prior art, the present invention has the following beneficial effects:

[0102] (1) The present invention can effectively improve the detection accuracy of the gas flow rate output by the pneumoperitoneum machine, especially when the gas flow rate is small and the pressure difference between the front and rear ends of the proportional valve 1 is small;

[0103] (2) The present invention improves the accuracy and stability of abdominal cavity air pressure during surgery;

[0104] (3) Using the system and method provided by the present invention does not require any additional cost compared to the prior art;

[0105] (4) The present invention can effectively avoid medical accidents caused by excessive fluctuations in abdominal cavity air pressure during surgery.

[0106] The above embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and replacements made by technicians in this field on the basis of the present invention fall within the scope of protection required by the present invention.

Claims

1. A high-precision detection method for the output gas flow rate of an insufflator, characterized in that: The following steps are involved: Detecting the air pressure at the front end and the rear end of the proportional valve using a first gas pressure sensor and a second gas pressure sensor, converting the acquired air pressure into a first electrical signal and a second electrical signal, respectively, and simultaneously sending the first electrical signal and the second electrical signal to a differential amplifier module; The differential amplification module obtains a difference between the first electrical signal and the second electrical signal received, amplifies the difference, and outputs the amplified difference to a programmable amplifier; After receiving the amplified difference, the programmable amplifier performs secondary amplification to obtain a secondary amplified difference; The ADC module collects the secondary amplified difference to obtain a sampling signal, and quantizes the sampling signal under the control of the MCU module to obtain quantized data; The MCU module reads the quantitative data, obtains the pressure difference between the front and rear ends of the first gas pressure sensor and the second gas pressure sensor according to the read quantitative data, and obtains the gas flow rate according to the pressure difference.

2. The high-precision detection method for the output gas flow rate of the pneumoperitoneum machine according to claim 1 is characterized in that: When the ADC module collects the secondary amplified difference, it includes: Performing anti-interference processing on the secondary amplified difference using a low-pass filter; The ADC module collects the secondary amplified difference after anti-interference processing to obtain a sampling signal.

3. The high-precision detection method for the output gas flow rate of the pneumoperitoneum machine according to claim 1 is characterized in that: When performing secondary amplification, it includes: The MCU module reads the sampling signal collected by the ADC module and determines whether the size of the sampling signal is within the optimal sampling range of the ADC module; If not, the MCU module adjusts the gain of the programmable amplifier according to the magnitude of the sampling signal until the magnitude of the sampling signal reaches the optimal sampling range of the ADC module; Among them, when the size of the sampling signal is 3 / 4 of the range of the ADC module, it is the optimal sampling range.

4. The high-precision detection method for the output gas flow rate of the pneumoperitoneum machine according to claim 1, characterized in that: The process of obtaining the gas flow rate according to the pressure difference is specifically shown in Formula 1, Formula 2 and Formula 3: Where q f is the gas flow rate, in m 3 / s, Δp is the pressure difference, ρ1 is the gas density, ε is the expansion coefficient, d is the inner diameter of the proportional valve, and D is the inner diameter of the pipe upstream of the proportional valve.

5. The high-precision detection method for the output gas flow rate of the pneumoperitoneum machine according to claim 1 is characterized in that: When the MCU module reads the quantitative data, it includes: It is determined whether the read quantized data has reached 128. If so, the reading of the quantized data is stopped.

6. The high-precision detection method for the output gas flow rate of the pneumoperitoneum machine according to claim 1 or 5, characterized in that: When obtaining the pressure difference between the front and rear ends of the first gas pressure sensor and the second gas pressure sensor, the method includes: The MCU module passes the read quantized data through Kalman filtering to improve stability and accuracy.

7. A high-precision detection system for the output gas flow rate of an insufflator, characterized in that: include: The first gas pressure sensor and the second gas pressure sensor are used to detect the air pressure at the front end and the rear end of the proportional valve, convert the acquired air pressure into a first electrical signal and a second electrical signal respectively, and simultaneously send the first electrical signal and the second electrical signal to the differential amplifier module; a differential amplification module, configured to obtain a difference between the first electrical signal and the second electrical signal, amplify the difference, and output the amplified difference; a programmable amplifier, configured to perform secondary amplification after receiving the amplified difference value to obtain a secondary amplified difference value; An ADC module is used to collect the secondary amplified difference to obtain a sampling signal, and quantize the sampling signal under the control of the MCU module to obtain quantized data; The MCU module is used to read the quantitative data, obtain the pressure difference between the front and rear ends of the first gas pressure sensor and the second gas pressure sensor according to the read quantitative data, and obtain the gas flow rate according to the pressure difference.

8. The high-precision detection system for the output gas flow rate of the insufflator according to claim 7, characterized in that: The differential amplification module is a differential operational amplifier.

9. The high-precision detection system for the output gas flow rate of the insufflator according to claim 7, characterized in that: Also includes: The low-pass filter is used to perform anti-interference processing on the secondary amplified difference to obtain the secondary amplified difference after anti-interference processing, and the secondary amplified difference is collected by the ADC module.

10. The high-precision detection system for the output gas flow rate of the insufflator according to claim 9, characterized in that: The low-pass filter is a Sallen-Key low-pass filter.

Images