Sensor data acquisition and processing device for diamond self-temperature sensing cutting tools

Abstract

The invention discloses a sensor data acquisition and processing device for a diamond self-temperature sensing tool. The device comprises a low-temperature drift multi-stage constant current source circuit, a voltage stabilizing circuit, a two-stage differential amplifier circuit, an analog-to-digital conversion circuit, a microprocessor main control circuit, a data transmission circuit, a user interaction circuit and a power management circuit. The sensor data is acquired by a four-wire method, that is, the voltage signal output by the diamond self-temperature sensing tool sensor is acquired by outputting an excitation current, different constant current source sizes are acquired, a microampere-level weak constant current source output is configured, a multi-stage resistor network is constructed to realize multi-speed switching of the constant current source, and effective acquisition of the millivolt / microvolt weak voltage signal of the self-temperature sensing diamond tool under the excitation current is realized. The sensor data acquired by acquisition and processing has high sensitivity, precision and response speed, and the temperature of the cutting area can be measured online.

Description

Technical Field

[0001] The invention relates to a diamond self-temperature sensing tool, in particular to a sensor data acquisition and processing device used for the diamond self-temperature sensing tool. Background Art

[0002] Single-point diamond turning is an extremely important processing technology in the field of modern advanced manufacturing. With its high-precision and high-efficiency processing properties, it is widely used in the manufacturing process of optical free surfaces, precision grinding tools, etc. Cutting temperature is one of the key parameters that reflects the complex thermal coupling effect in the cutting process. It is particularly important for measuring cutting conditions such as machined surface size, shape accuracy, cutting chatter, and tool wear.

[0003] Peripheral circuits such as excitation signal circuits and signal processing circuits are important components of the diamond self-temperature sensing tool system. The accuracy of their output digital signals directly determines the signal accuracy of the diamond self-temperature sensing tool system.

[0004] Many types of sensors (such as strain gauges, pressure sensors, etc.) require an external excitation signal to work. The excitation signal is usually a voltage or current, and its purpose is to enable the sensor to respond and produce a signal representing the measured value. The excitation signal circuit ensures that the sensor receives a stable and appropriate excitation, thereby ensuring the accuracy of the measurement.

[0005] The Chinese patent application with publication number CN115847637A discloses an online temperature measurement device for the cutting area during a single-point diamond turning process, including a temperature-sensitive diamond tool, a tool housing, and a temperature acquisition circuit, wherein a conductive path is formed between the temperature-sensitive diamond tool and the temperature acquisition circuit; the temperature acquisition circuit acquires the voltage change of the temperature-sensitive diamond tool during the cutting process and converts it into a temperature signal; the temperature-sensitive diamond tool is modified into a diamond semiconductor by boron-hydrogen co-doping, and the inherent resistance of the semiconductorized diamond tool material changes with temperature to achieve the measurement of the temperature of the cutting area. The present invention can measure the online temperature of the quasi-cutting area at a micro-nano cutting scale with high sensitivity and high response speed, and the invention has extremely strong practicality and broad application prospects. However, the scheme still has defects such as low sensitivity, low precision, and slow response speed. Summary of the invention

[0006] The present invention aims to solve the existing problems in the data collection and processing of diamond self-temperature sensing tools and provides a sensor data collection and processing device for diamond self-temperature sensing tools, which is beneficial to improving sensitivity, accuracy and response speed and can measure the temperature of the cutting area online.

[0007] In order to solve the above technical problems, the scheme of the present invention adopts a sensor data acquisition and processing device for diamond self-temperature sensing tool, including a diamond self-temperature sensing tool sensor and a power supply voltage stabilization circuit, and also includes a low-temperature drift multi-stage constant current source circuit, a two-stage differential amplifier, a low-pass filter, a power management circuit, a user interaction circuit, a data transmission circuit, an analog-to-digital conversion circuit and a microprocessor main control circuit, wherein the low-temperature drift multi-stage constant current source circuit includes a low-temperature drift multi-stage constant current source, a resistor configuration logic array, a two-stage differential amplifier circuit and a low-pass filter, and the diamond self-temperature sensing tool sensor outputs a voltage signal under the excitation of the low-temperature drift multi-stage constant current source circuit, which is connected to the two-stage differential amplifier, The low-pass filter, the two-stage differential amplifier, and the low-pass filter rear stage are electrically connected to the analog-to-digital conversion circuit and the microprocessor main control circuit in sequence. The microprocessor main control circuit controls the electrically connected user interaction circuit, the data transmission circuit, and the resistor configuration logic array. The microprocessor main control circuit controls the pipeline power management circuit through the data transmission circuit. The power management circuit provides a voltage stabilization circuit power supply for sensor data acquisition and processing; the multi-stage low-temperature drift constant current source excitation current is output through the low-temperature drift multi-stage constant current source circuit, and the high-precision voltage acquisition circuit is formed through the two-stage differential amplifier circuit, the low-pass filter, and the analog-to-digital conversion circuit. The high-precision voltage acquisition circuit realizes high-precision acquisition and real-time output of sensor data. Provide multi-stage low-temperature drift multi-stage constant current source output to realize the effective acquisition of millivolt / microvolt weak voltage signals of self-sensing diamond tools under the excitation current. The sensor data obtained by acquisition and processing has high sensitivity, high precision, and high response speed, and can measure the temperature of the quasi-cutting area online.

[0008] Preferably, the low temperature drift multi-stage constant current source circuit adopts an adjustable current source main control chip of model LM334, and obtains constant current sources of different sizes by electrically connecting and configuring different peripheral resistors to the LM334 chip, and uses a four-channel single-pole double-throw logic switch group chip of model CH444G and a microprocessor main control circuit to realize the configuration switching of the four-stage peripheral resistor network of the LM334 chip, and electrically connects and configures a negative temperature coefficient diode for temperature compensation. Improve the stability of the positive temperature coefficient output current and improve the effectiveness of temperature drift compensation. Improve the simplicity, reliability, stability and effectiveness of the configuration switching of the four-stage peripheral resistor network, and improve the stability, reliability and effectiveness of the output of the four-stage low temperature drift multi-stage constant current source.

[0009] Preferably, the two-stage differential amplifier circuit includes an operational amplifier circuit chip of model OPA2333 and its peripheral passive circuit. By specifying whether the chip resistor is welded at a specified position, the single-stage operational amplifier or two-stage operational amplifier working mode can be switched to adapt to multiple working conditions, thereby improving the flexibility, stability and effectiveness of the two-stage differential operational amplifier working mode.

[0010] Preferably, the analog-to-digital conversion circuit includes a 16-bit analog-to-digital conversion chip of model ADS8866 and its peripheral passive circuits; and an input-end RC filter is configured to filter out signal broadband noise and attenuate sampling charge injection from the switched capacitor input stage of ADS8866. ADS8866 has a 16-bit sampling channel and a sampling frequency of up to 100kHz, which is extremely suitable for low-power and low-rate applications. It has high sampling rate, high sampling accuracy, and high cost-effectiveness in sampling processing analog-to-digital conversion.

[0011] Preferably, the diamond self-temperature sensing tool sensor is electrically connected to the diamond self-temperature sensing tool through a silver wire, thereby reducing the attenuation of the electrical connection signal collected by the diamond self-temperature sensing tool sensor and improving the stability, reliability and effectiveness of the sensor signal collection.

[0012] Preferably, the low temperature drift multi-stage constant current source circuit outputs a multi-stage low temperature drift constant current source excitation current gear of 100nA, 1μA, 10μA and 100μA, thereby improving the high precision and high sensitivity of the multi-stage output excitation signal of the low temperature drift multi-stage constant current source output constant current source.

[0013] Preferably, the two-stage differential amplifier circuit is composed of a dual-channel operational amplifier circuit chip of model OPA2333 and its peripheral circuits. The first resistor R1 at the output end and the third capacitor C3 form a low-pass filter to filter out high-frequency noise. When the 20th resistor R20 and the 21st resistor R21 are welded and the 22nd resistor R22 is not welded, two amplifier stages work for 22500 times high-magnification signal amplification; when the 20th resistor R20 and the 21st resistor R21 are not welded and the 22nd resistor R22 is welded, a single amplifier stage works for 150 times lower-magnification signal amplification. The two-stage differential signal amplification and noise reduction are improved to obtain flexibility and effectiveness.

[0014] Preferably, the user interaction circuit includes an OLED display screen and a control button circuit, the control button circuit includes a power switch part and a constant current source gear switching part, the power switch part realizes power off by long pressing the lockless switch, the long press detection is realized by a touch simulation button chip of model EC90708, and the power switch is controlled by a driving transistor circuit, the constant current source gear switching realizes level conversion of the lockless switch pin by short pressing the lockless switch, the level detection, i.e., short press detection, is realized by an external interrupt of the single-chip microcomputer, and the constant current source gear switching is realized by changing the output state of the single-chip microcomputer IO port; the OLED screen at least displays the remaining power of the lithium battery carried by the current circuit device, the sensor detection signal, and the output constant current source gear. Improve the user interaction control operation display to be simple, convenient, flexible and effective.

[0015] Preferably, a ground-level loop surrounds the signal processing level circuit, and the ground-level loop surrounds the signal processing level circuit, which is arranged on the top layer of the sensor data acquisition and processing device PCB, and a low-temperature drift multi-stage constant current source circuit, a two-stage differential amplifier circuit and a low-pass filter are arranged on the top layer of the PCB, and the ground level of the low-temperature drift multi-stage constant current source circuit, the two-stage differential amplifier circuit and the analog-to-digital conversion circuit adopts a ground-level loop to surround the signal processing level circuit protection structure; the bottom layer of the PCB is fully copper-plated and uses multiple vias to conduct well with the top-level ground-level loop, and a shielding cover made of white copper is welded on the ground-level loop to form an internal shielding layer. The shielding cover is formed by white copper to achieve shielding of external electromagnetic interference, while curbing the harm of static electricity and surge current to the device, and improving the electromagnetic compatibility of the system. Improve the effectiveness of the protection of the sensor data acquisition and processing device in shielding external electromagnetic interference, static electricity and surge current.

[0016] Preferably, each level of the four-level peripheral resistor network is composed of two pairs of parallel resistors, and different low-temperature drift constant current source outputs are achieved by switching different levels of resistors, thereby improving the high-precision, stable, reliable and effective output of different low-temperature drift constant current source excitation signals.

[0017] The beneficial effects of the present invention are: providing a multi-stage low-temperature drift multi-stage constant current source output, realizing effective acquisition of millivolt / microvolt weak voltage signals of self-sensing diamond tools under excitation current, and acquiring and processing sensor data with high sensitivity, precision, and response speed, and online measurement of the temperature of the quasi-cutting area. A set of special data acquisition and processing circuit devices is provided for the diamond temperature-sensing tool sensor in the invention patent with application number 202211585437.7, which provides a precise and stable excitation signal source for the self-sensing tool sensor, and amplifies, filters, acquires, and transmits the weak signal output by the sensor. It has high integration and sophisticated layout, and can realize online temperature measurement of the quasi-cutting area at the micro-nano cutting scale with high sensitivity and high response speed. The invention has extremely strong practicality and broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The present invention is a schematic block diagram of the principle structure of the sensor data acquisition and processing device for diamond self-temperature sensing cutting tools.

[0019] Figure 2 The invention is a schematic diagram of the circuit principle of a low temperature drift multi-stage constant current source circuit in a sensor data acquisition and processing device for a diamond self-temperature sensing tool.

[0020] Figure 3 The present invention is a schematic diagram of the circuit principle of a two-stage differential amplifier circuit in a sensor data acquisition and processing device for a diamond self-temperature sensing tool.

[0021] Figure 4The present invention is a schematic diagram of the circuit principle of an analog-to-digital conversion circuit in a sensor data acquisition and processing device for a diamond self-temperature sensing tool.

[0022] Figure 5 The present invention is a schematic diagram of the circuit principle of the STM32 microprocessor main control circuit in the sensor data acquisition and processing device for the diamond self-temperature sensing tool.

[0023] Figure 6 The present invention is a schematic diagram of the circuit principle of a low-power Bluetooth circuit in a data transmission circuit in a sensor data acquisition and processing device for a diamond self-temperature sensing tool.

[0024] Figure 7 The present invention is a schematic diagram of the circuit principle of a USB data transmission circuit in a data transmission circuit in a sensor data acquisition and processing device for a diamond self-temperature sensing tool.

[0025] Figure 8 The present invention is a schematic diagram of the circuit principle of a voltage stabilizing circuit in a sensor data acquisition and processing device for a diamond self-temperature sensing cutting tool.

[0026] Fig. 9 It is a schematic diagram of the circuit principle for realizing charging management and power supply scheme switching management in the power management circuit of the sensor data acquisition and processing device for the diamond self-temperature sensing tool of the present invention.

[0027] Fig.10 The present invention is a schematic diagram of the circuit principle for realizing power disconnection management in a power management circuit in a sensor data acquisition and processing device for a diamond self-temperature sensing tool.

[0028] Fig.11 The present invention is a schematic diagram of the circuit principle of the device for static electricity and surge protection in the sensor data acquisition and processing device for the diamond self-temperature sensing tool.

[0029] Fig.12 It is a schematic diagram of the structure of the sensor data acquisition and processing device for the diamond self-temperature sensing tool of the present invention and a schematic diagram of the layout of components on the front and back sides of the PCB layout.

[0030] Explanation of the accompanying symbols: 1- low temperature drift constant current source circuit; 2- two-stage signal amplifier circuit; 3- single chip program download BOOT configuration; 4- reset button; 5- control button; 6- TYPE-C interface; 7- sensor interface; 8- logic switch; 9- constant current source resistor array; 10- analog-to-digital conversion circuit; 11- power on / off circuit; 12- voltage stabilizing circuit; 13- lithium battery charging status indicator; 14- UART to USB circuit; 15- lithium battery interface; 16- 0.91 inch OLED screen interface; 17- circuit protection ring; 18- external crystal oscillator; 19- STMF103C8T6; 20- low power consumption wireless Bluetooth; 21- power supply scheme switching circuit; 22- lithium battery charging management; 23- surge and electrostatic protection diode; 24- circuit board; 25- white copper shielding cover; 26- 0.91 inch OLED screen. Among them Fig.12 Among them, 1, 8, and 9 constitute a low-temperature drift multi-stage constant current source circuit, 3 constitutes a two-stage signal amplification circuit, 10 constitutes an analog-to-digital conversion circuit, 3, 4, 18, and 19 constitute an STM32 microprocessor main control circuit, 5 and 16 constitute a user interaction circuit, 14 and 20 constitute a data transmission circuit, 12 constitutes a voltage stabilization circuit, 11, 13, 15, 21, and 22 constitute a power management circuit, and 17, 23, and 25 constitute a protection structure for electromagnetic interference, static electricity, and surge current. DETAILED DESCRIPTION

[0031] Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 , Fig. 9 , Fig.10 , Fig.11 , Fig.12In the embodiment shown, a sensor data acquisition and processing device for a diamond self-temperature sensing tool comprises a diamond self-temperature sensing tool sensor and a power supply voltage stabilization circuit, and also comprises a low-temperature drift multi-stage constant current source circuit, a two-stage differential amplifier, a low-pass filter, a power management circuit, a user interaction circuit, a data transmission circuit, an analog-to-digital conversion circuit and a microprocessor main control circuit, wherein the low-temperature drift multi-stage constant current source circuit comprises a low-temperature drift multi-stage constant current source and a resistor configuration logic array, and the output voltage signal of the diamond self-temperature sensing tool sensor under the excitation of the low-temperature drift multi-stage constant current source circuit is connected to the two-stage differential amplifier and the low-pass filter, and the two-stage differential amplifier and the low-pass filter are connected to the two-stage differential amplifier and the low-pass filter. The back stage is electrically connected to the analog-to-digital conversion circuit and the microprocessor main control circuit in sequence. The microprocessor main control circuit controls the electrically connected user interaction circuit, the data transmission circuit and the resistor configuration logic array. The microprocessor main control circuit controls the pipeline power management circuit through the data transmission circuit. The power management circuit provides a voltage stabilization circuit power supply for sensor data acquisition and processing; the multi-stage low-temperature drift constant current source excitation current is output through the low-temperature drift multi-stage constant current source circuit, and a high-precision voltage acquisition circuit is formed through a two-stage differential amplifier circuit, a low-pass filter and an analog-to-digital conversion circuit. The high-precision voltage acquisition circuit realizes high-precision acquisition and real-time output of sensor data for diamond self-temperature sensing tools. The resistor configuration logic array obtains the resistor configuration state when the constant current is output according to the four microprocessor main control circuit logic signals, and forms four different low-temperature drift constant current source outputs to realize high-precision acquisition and real-time output of sensor data for diamond self-temperature sensing tools.

[0032] The low-temperature drift multi-level constant current source circuit adopts the adjustable current source main control chip model LM334, and obtains constant current sources of different sizes by electrically connecting different peripheral resistors to the LM334 chip. The negative temperature coefficient diode 1N457 is used for temperature compensation. The four-channel single-pole double-throw logic switch group chip model CH444G and the SMT32MCU microprocessor main control circuit are used to realize the configuration switching of the four-level peripheral resistor network of the LM334 chip, and the negative temperature coefficient diode is electrically connected for temperature compensation.

[0033] The two-stage differential amplifier circuit includes an operational amplifier circuit chip of model OPA2333 and its peripheral passive circuits, which can be switched to single-stage operational amplifier or two-stage operational amplifier working mode to adapt to multiple working conditions by welding the chip resistor at the specified position. The analog-to-digital conversion circuit includes a 16-bit analog-to-digital conversion chip of model ADS8866 and its peripheral passive circuits; and an input RC filter is configured to filter out signal broadband noise and attenuate the sampling charge injection from the switch capacitor input stage of ADS8866. The diamond self-sensing temperature tool sensor is electrically connected to the diamond self-sensing temperature tool through a silver wire. The low-temperature drift multi-stage constant current source circuit outputs a multi-stage low-temperature drift constant current source excitation current gear of 100nA, 1μA, 10μA and 100μA. The two-stage differential amplifier circuit is composed of a dual-channel operational amplifier circuit chip of model OPA2333 and its peripheral circuits. The first resistor R1 at the output end and the third capacitor C3 form a low-pass filter to filter out high-frequency noise. When the 20th resistor R20 and the 21st resistor R21 are welded, and the 22nd resistor R22 is not welded, the two amplifier stages work and are used for 22500 times high-magnification signal amplification occasions; when the 20th resistor R20 and the 21st resistor R21 are not welded, and the 22nd resistor R22 is welded, a single amplifier stage works and is used for 150 times lower-magnification signal amplification occasions.

[0034] The user interaction circuit includes an OLED display and a control button circuit. The control button circuit includes a power switch part and a constant current source gear switching part. The power switch part realizes power off by long pressing the lockless switch. The long press detection is realized by a touch simulation button chip of model EC90708, and the power switch is controlled by a driving transistor circuit. The constant current source gear switching realizes level conversion of the lockless switch pin by short pressing the lockless switch. The level detection, i.e., short press detection, is realized by an external interrupt of the single-chip microcomputer, and the constant current source gear switching is realized by changing the output state of the single-chip microcomputer IO port; the OLED screen at least displays the remaining power of the lithium battery carried by the current circuit device, the sensor detection signal, and the output constant current source gear. The OLED screen can use a 0.91-inch monochrome OLED display, and of course, it can also use OLED displays of other specifications.

[0035] The invention has a ground-level loop surrounding the signal processing level circuit, which is arranged on the top layer of the PCB of the sensor data acquisition and processing device, and a low-temperature drift multi-level constant current source circuit, a two-level differential amplifier and a low-pass filter are arranged on the top layer of the PCB. The low-temperature drift multi-level constant current source circuit, the two-level differential amplifier and the low-pass filter adopt a ground-level loop surrounding the signal processing level circuit protection structure; the bottom layer of the PCB is fully copper-plated at the ground level and multiple vias are used to conduct well with the top-level ground loop. A white copper material shielding cover is welded on the ground-level loop to form an internal shielding layer cover to achieve shielding of external electromagnetic interference, while curbing the harm of static electricity and surge current to the device, and improving the electromagnetic compatibility of the system. Each level of the four-level peripheral resistor network is composed of two pairs of parallel resistors, and different low-temperature drift constant current source outputs are achieved by switching different levels of resistors. The data transmission circuit supports wired transmission, and uses USB to connect to the computer to upload sensor data. At the same time, the circuit also supports wireless transmission, and uses low-power wireless Bluetooth to upload data.

[0036] The microprocessor main control circuit uses STM32F103C8T6 as the control core, equipped with an 8MHz external crystal oscillator, and the Bootloader program download configuration circuit. The voltage stabilization circuit is composed of the TPS63031DSKR power chip and its peripheral passive circuits, supporting 3.7-5.5V DC power input and 3.3V constant voltage output.

[0037] The power management circuit includes three parts: automatic switching of power supply mode, logic switch, and lithium battery charging management. The default power supply mode of the device is lithium battery power supply. The lithium battery charging management performs the charging management task of the lithium battery. When the USB data cable / USB (TYPE-C) is connected, it automatically switches to the external power supply mode and charges the lithium battery on board, and lights up the red indicator light; if the lithium battery voltage reaches 4.2V, it automatically cuts off the charging and lights up the green indicator light. The automatic switching of power supply mode and the logic switch automatically switch the logic switch to the voltage stabilization circuit according to whether the USB data cable / USB (TYPE-C) is connected.

[0038] like Figure 2As shown in the figure, in order to improve the temperature measurement accuracy of boron-doped diamond, the Kelvin four-wire detection method is used for non-interference resistance measurement. This method uses separate current loading and voltage detection electrodes, so a stable constant current source is required to provide excitation current. In order to reduce the influence of the thermal effect of the current on the cutting temperature of boron-doped diamond measurement, a low-temperature drift multi-stage constant current source circuit is designed as the current output. At the same time, the low-temperature drift multi-stage constant current source circuit causes the output current to be non-constant due to the existence of the positive temperature coefficient, and the temperature drift needs to be compensated. Considering the above factors, the LM334 power chip (U1) is selected as the constant current source control chip. The chip can work normally in the range of 0℃ to 10℃, has an output capacity of 1μA to 10mA and a positive temperature coefficient of 0.227mV / ℃. In order to eliminate the temperature dependence of LM334, a silicon diode 1N457 (D2) with a negative temperature coefficient (-2.5mV / ℃) is used to compensate for its temperature drift.

[0039] The configuration method refers to the LM334 chip data sheet provided by Texas Instruments. The specific implementation plan is as follows:

[0040] The resistors in the left and right dashed boxes are considered as a whole, denoted as RA and RB respectively. The current output from VTEST is , which is the current of the two branches RA and RB and as well as Bias current output from pin The sum of

[0041]

[0042] In the formula, , . = 0.6v for the R pin of U1 and The voltage difference between the pins, =67.7mV is the voltage drop of D2. In order to facilitate subsequent calculations, the chip manual recommends increasing the voltage value by 5.9%. Offset bias current For setting current The configuration of RA and RB should make the temperature coefficient of the circuit 0, that is, satisfy =0, the ratio between the two is calculated as: ≈10, from which we can calculate the specified The required resistor configurations are RA and RB.

[0043] Set the current output range The resistors are 100nA, 1uA, 10uA, and 100uA, and the final resistor configuration is as follows:

[0044] 100μA: RA = 1.37kΩ, RB = 13.7kΩ (R23, R1 in the figure);

[0045] 10μA: RA = 13.7kΩ, RB = 137kΩ (R15, R18 in the figure);

[0046] 1μA: RA=137kΩ, RB=1.37MΩ=2.2MΩ / / 3.6MΩ (R9, R8, R10 in the figure);

[0047] 0.1μA: RA=1.37MΩ=2.2MΩ / / 3.6MΩ, RB=13.7MΩ=20MΩ / / 43MΩ; (R7, R2, R3, R6 in the figure);

[0048] Among them, " / / " represents parallel connection. Because some calculated resistance values ​​cannot directly obtain the corresponding standard resistance, two standard resistors of different sizes (0.1%) are needed to be connected in parallel for matching. In the figure, R8 / / R10, R7 / / R2, and R3 / / R6 are all connected in parallel to obtain the required resistance value.

[0049] The reason why multiple constant current sources are set to output excitation signals is that different boron-doped diamonds have different ranges of resistance values, and a single constant current source is not universal. The switching function of different excitation signal gears depends on the analog switch module CH444G chip KEY1. This is an analog switch chip with a rated power supply voltage of 5V, which includes a 2-channel single-pole four-throw analog switch. The chip has high bandwidth and low on-resistance (about 20Ω). After the chip is enabled (IEN is grounded), the logic signal from the microprocessor is received through the two control pins IN0 and IN1, and the current switching of four gears can be realized, that is, (IN0, IN1) = (11), (10), (01), (00) four logic input states, corresponding to the resistance configuration states of 0.1μA, 1μA, 10μA, and 100μA when the four constant current outputs are respectively. The temperature drift compensation of the LM334 chip in the circuit is particularly important, so when laying out the PCB, the silicon diode D2 and the LM334 components should be as close as possible.

[0050] like Figure 3 As shown in the figure, since the excitation current input to the boron-doped diamond is small, the voltage signal at its output is also small, which is not conducive to direct sampling, so a differential amplifier circuit is needed to amplify the measured voltage signal. The inverting input of the amplifier is grounded, and its amplification factor is A=R4 / R11=150. The OPA2333 dual-channel precision operational amplifier U10 is selected. This type of operational amplifier has high precision, low quiescent current, high impedance input, good stability, almost zero temperature drift coefficient, and can provide extremely low offset voltage (10µV).

[0051] also, Figure 3 R1 and C3 form a passive low-pass amplifier at the output end, and its cut-off frequency is The calculation method is as follows:

[0052]

[0053] When R20 and R21 are welded but R22 is not welded, two amplifier stages work and are used for 150×150=22500 times high-magnification signal amplification. When R20 and R21 are not welded but R22 is welded, a single amplifier stage works and is used for 150 times lower-magnification signal amplification.

[0054] like Figure 4 As shown in the figure, the analog-to-digital conversion circuit is a circuit structure that converts analog signals (such as voltage or current) into digital values ​​that can be processed by the digital system. Considering the sampling rate, sampling accuracy, price and other factors, the ADS8866 chip (U4) is selected. The ADS8866 has a 16-bit sampling channel and a sampling frequency of up to 100kHz, which is extremely suitable for low-power and low-rate applications. According to the chip manual provided by Texas Instruments, the chip input pin DIN is directly connected to DVDD, the CONVST pin is used as the chip select signal (CS) of the SPI, and the working mode of the chip is configured to 3-wire mode. At the rising edge of CONVST, the ADS8866 chip samples the input signal, and the device enters the conversion stage. After the conversion is completed, the device enters the acquisition stage, and then reads the data at the falling edge of the SPI clock signal. It should be noted here that the STM32F103 needs to set the clock idle state of the SPI bus to a low level, and the trigger edge signal is configured to trigger the second edge signal.

[0055] like Figure 5 As shown in the figure, the single-chip minimum system is mainly composed of STM32F103C8T6 chip, crystal oscillator circuit, reset circuit, program burning circuit and other parts, which are the control core of the whole circuit system. The crystal oscillator X2 uses 8MHz passive crystal oscillator with ground shielding cover, and the program burning uses serial port burning. Therefore, it is necessary to configure the startup mode of STM32F103C8T6 chip through the dip switch SW1, and use the main flash memory (MainFlash) startup mode for normal operation. User interaction is mainly realized by OLED screen H1 and control button KEY2.

[0056] like Figure 6As shown, the Bluetooth circuit uses Qinheng's BLE-SER Bluetooth to serial port circuit (BLE_MODE1). This circuit is developed based on the CH9140 chip, supports Bluetooth BLE4.2, and the serial port baud rate is up to 1Mbps. It supports Bluetooth master-slave mode or slave mode. The master-slave mode can be automatically connected or bound. The BLE_MODE pin in the circuit is grounded, and the Bluetooth circuit is set to slave mode. Communication is achieved with STM32F103C8T6 through the serial ports U_TX and U_RX.

[0057] like Figure 7 As shown, UART to USB data is realized through CP2102 serial port chip U6, and TYPE-C16Pin interface USB1 is used to output data. USB_DP and USB_DN are USB signal lines, 5V_USB_EXT is the power supply of USB1 input device, to ensure that computers and other devices can correctly identify CP2102 chip, USB1 interface CC1 and CC2 pins are grounded through R38 and R41 respectively, and the ground level GND is separated from the device analog ground through R43.

[0058] like Figure 8 As shown, the voltage reference is a key component of the analog-to-digital conversion circuit and must be stable and precisely controlled to ensure that the ADC circuit can accurately convert the analog signal into a digital value. The 3V3 output by the TPS63031 voltage regulator chip U3 is used as the reference power supply and the power supply voltage of the ADC circuit.

[0059] like Fig. 9 As shown in the figure, the charging circuit consists of the TP4056 chip U2 and its peripheral circuits. TP4056 is a widely used lithium battery charging solution in embedded development. The chip is compatible with USB power supply, has a small size and good heat dissipation performance, and uses a PMOSFET architecture internally, with an anti-reverse charging circuit. When the battery is fully charged, the voltage is 4.2V, and the size of the charging current can be configured through an external resistor R13. When the battery voltage reaches the full-charge voltage, the charging current drops to one-tenth of the set value, and the TP4056 will automatically terminate the charging cycle. When the input voltage is cut off, the TP4056 will automatically enter a low-current state and reduce the battery current to less than 2uA. In order to ensure that the self-sensing temperature tool system has a continuous battery life of more than 6 hours, a 650mAh lithium battery (VBAT) is selected, and the charging current is configured to be 250mA, corresponding to the size of the external resistor R13 of 5kΩ.

[0060] To ensure the healthy use of the battery, when the external USB power supply is connected, the transistor Q1 is cut off, so that the lithium battery does not power the device. TP4056 will detect the lithium battery voltage. If the voltage is lower than 4.2V, the lithium battery will be charged, otherwise there will be no response. When the external USB power supply is disconnected, the transistor Q1 is turned on, so that the lithium battery powers the device. Schottky diode D1 prevents the device current from flowing back to the external USB device.

[0061] like Fig.10 As shown, the switch circuit is composed of PMOS tube Q2, NPN transistor Q3 and EC190708 chip U8. Q2 is not turned on when powered on, and the circuit system does not work. Press and hold the control button for 3 seconds, the SEL pin of EC190708 outputs a high level, Q3 pulls down the gate (G) of Q2, making its source (S) and drain (D) conductive, and the system starts to work. Press and hold the control button for 3 seconds during operation, SEL outputs a low level, at which time the S pole and D pole of Q2 are cut off, and the system shuts down.

[0062] like Fig.11 As shown in the figure, the external access equipment lines are all protected against static electricity and surges using bidirectional ESD diodes D3, D4, D5, and D6, and the diode limit voltage is 5V. Figure 1 The areas where 1, 2, 8, 9, and 10 are located are electromagnetically shielded with a white copper shielding cover, which fits the box surrounding the area in the figure, and the shielding cover is connected to the device simulation ground at multiple points.

[0063] This embodiment is a supporting data acquisition and processing device for the diamond temperature-sensing tool sensor in the invention patent with application number 202211585437.7. The present invention uses a four-wire method to collect sensor data, that is, first collect the voltage signal output by the diamond self-temperature-sensing tool sensor by outputting the excitation current, and then use Ohm's law and the resistance-temperature sensor characteristics to obtain temperature data. Among them, the excitation current is generated by a constant current source circuit, and different constant current source sizes are obtained by configuring different peripheral resistors of the LM334 chip. A negative temperature coefficient diode is used for temperature compensation to balance the temperature drift. A microampere-level weak constant current source output is configured to reduce the heat generated by the sensor. In order to adapt to sensors with different resistance ranges, a multi-stage resistor network is built to realize multi-speed switching of the constant current source. In order to realize the effective collection of the millivolt / microvolt weak voltage signal of the self-temperature-sensing diamond tool under the excitation current, a two-stage differential amplifier is used to amplify the voltage signal, and the appropriate excitation current and amplification gain are selected to make the collected voltage signal reach the level of 1 to 3V. The analog-to-digital conversion circuit is used to quantify the size of the voltage signal, convert the voltage signal into a digital signal that can be recognized by the microcontroller and input it into the microcontroller for processing through the serial peripheral interface (SPI). Considering the sampling accuracy requirements, power consumption and sampling rate, the 16-bit analog-to-digital conversion chip ADS8866 is selected to realize the analog-to-digital conversion. In order to achieve efficient data transmission, the microcontroller packages and encodes the collected data and then sends it to the data transmission circuit. In order to meet the needs of multi-condition data collection, wireless Bluetooth and wired USB data transmission channels are designed to realize data transmission, and different data transmission methods can be selected according to different needs. In addition, a series of other circuits are designed, including a lithium battery management circuit, which realizes the charging of lithium batteries when connected to an external USB, and uses a transistor circuit to realize the automatic switching between USB power supply and battery power supply; a user interaction circuit, which uses an OLED display to output sensor measurement information and excitation current output gear, battery power, and uses a single button to long press and short press to respectively realize power on and off control and current gear switching.

[0064] The following table is a brief list of component models used in the device in the embodiment of the present invention.

[0065]

[0066]

[0067]

[0068] The above content and structure describe the basic principle, main features and advantages of the product of the present invention, which should be understood by those skilled in the art. The above examples and descriptions are only for explaining the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which are within the scope of the present invention. The scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A sensor data acquisition and processing device for a diamond self-temperature sensing tool, comprising a diamond self-temperature sensing tool sensor and a power supply stabilizing circuit, characterized in that: It also includes a low-temperature drift multi-stage constant current source circuit, a two-stage differential amplifier, a low-pass filter, a power management circuit, a user interaction circuit, a data transmission circuit, an analog-to-digital conversion circuit and a microprocessor main control circuit, wherein the low-temperature drift multi-stage constant current source circuit includes a low-temperature drift multi-stage constant current source, a resistor configuration logic array, a two-stage differential amplifier circuit and a low-pass filter. The diamond self-temperature sensing tool sensor outputs a voltage signal under the excitation of the low-temperature drift multi-stage constant current source circuit and connects to the two-stage differential amplifier and the low-pass filter. The two-stage differential amplifier and the low-pass filter are electrically connected to the analog-to-digital conversion circuit and the microprocessor main control circuit in sequence. The microprocessor main control circuit controls the electrically connected user interaction circuit, the data transmission circuit and the resistor configuration logic array. The microprocessor main control circuit controls the pipeline power management circuit through the data transmission circuit. The power management circuit provides a voltage stabilizing circuit power supply for sensor data acquisition and processing; the multi-stage low-temperature drift constant current source excitation current is output through the low-temperature drift multi-stage constant current source circuit, and a high-precision voltage acquisition circuit is formed through the two-stage differential amplifier circuit, the low-pass filter and the analog-to-digital conversion circuit. The high-precision voltage acquisition circuit realizes high-precision acquisition and real-time output of sensor data.

2. The sensor data acquisition and processing device for diamond self-temperature sensing cutting tools according to claim 1, characterized in that: The low-temperature drift multi-level constant current source circuit adopts an adjustable current source main control chip of model LM334, and obtains constant current sources of different sizes by electrically connecting and configuring different peripheral resistors to the LM334 chip, uses a four-channel single-pole double-throw logic switch group chip of model CH444G and a microprocessor main control circuit to realize the configuration switching of the four-level peripheral resistor network of the LM334 chip, and electrically connects and configures a negative temperature coefficient diode for temperature compensation.

3. The sensor data acquisition and processing device for diamond self-temperature sensing cutting tools according to claim 1, characterized in that: The two-stage differential amplifier circuit includes an operational amplifier circuit chip of model OPA2333 and its peripheral passive circuits.

4. The sensor data acquisition and processing device for a diamond self-temperature sensing tool according to claim 1, characterized in that: The analog-to-digital conversion circuit includes a 16-bit analog-to-digital conversion chip of model ADS8866 and its peripheral passive circuits; and an input-end RC filter is configured to filter out signal broadband noise and attenuate sampling charge injection from the switched capacitor input stage of ADS8866.

5. The sensor data acquisition and processing device for diamond self-temperature sensing cutting tools according to claim 1, characterized in that: The diamond self-temperature sensing tool sensor is electrically connected to the diamond self-temperature sensing tool through a silver wire.

6. The sensor data acquisition and processing device for a diamond self-temperature sensing tool according to claim 1, characterized in that: The low-temperature drift multi-stage constant current source circuit outputs a multi-stage low-temperature drift constant current source excitation current gear of 100nA, 1μA, 10μA and 100μA.

7. The sensor data acquisition and processing device for a diamond self-temperature sensing tool according to claim 1, characterized in that: The two-stage differential amplifier circuit is composed of a dual-channel operational amplifier circuit chip of model OPA2333 and its peripheral circuits. The first resistor R1 at the output end and the third capacitor C3 form a low-pass filter to filter out high-frequency noise. When the 20th resistor R20 and the 21st resistor R21 are welded and the 22nd resistor R22 is not welded, the two amplifier stages work and are used for 22500 times high-magnification signal amplification occasions; when the 20th resistor R20 and the 21st resistor R21 are not welded and the 22nd resistor R22 is welded, a single amplifier stage works and is used for 150 times lower-magnification signal amplification occasions.

8. The sensor data acquisition and processing device for a diamond self-temperature sensing tool according to claim 1, characterized in that: The user interaction circuit includes an OLED display screen and a control button circuit. The control button circuit includes a power switch part and a constant current source gear switching part. The power switch part realizes power off by long pressing the lockless switch. The long press detection is realized by a touch simulation button chip with model EC190708, and the power switch is controlled by a driving transistor circuit. The constant current source gear switching realizes level conversion of the lockless switch pin by short pressing the lockless switch. The level detection, i.e., short press detection, is realized by an external interrupt of the single-chip microcomputer, and the constant current source gear switching is realized by changing the output state of the single-chip microcomputer IO port; the OLED screen at least displays the remaining power of the lithium battery carried by the current circuit device, the sensor detection signal, and the output constant current source gear.

9. The sensor data acquisition and processing device for a diamond self-temperature sensing tool according to claim 1, characterized in that: The invention has a ground-level loop surrounding a signal processing-level circuit, which is arranged on the top layer of the PCB of the sensor data acquisition and processing device, and a low-temperature drift multi-stage constant current source circuit, a two-stage differential signal amplification circuit and a low-pass filter are arranged on the top layer of the PCB. The low-temperature drift multi-stage constant current source circuit, the two-stage differential amplification circuit and the low-pass filter adopt a ground-level loop surrounding the signal processing-level circuit protection structure; the bottom layer of the PCB is fully copper-plated at the ground level and multiple vias are used to achieve good conduction with the top-layer ground-level loop, and a white copper material shielding cover is welded on the ground-level loop to form an internal shielding layer.

10. The sensor data acquisition and processing device for a diamond self-temperature sensing tool according to claim 2, characterized in that: Each level of the four-level peripheral resistor network is composed of two pairs of parallel resistors, and different low-temperature drift constant current source outputs are achieved by switching different levels of resistors.

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