CN215865238U - Electronic compass based on novel weak magnetic sensor - Google Patents
Electronic compass based on novel weak magnetic sensor Download PDFInfo
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- CN215865238U CN215865238U CN202121352752.6U CN202121352752U CN215865238U CN 215865238 U CN215865238 U CN 215865238U CN 202121352752 U CN202121352752 U CN 202121352752U CN 215865238 U CN215865238 U CN 215865238U
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Abstract
The utility model discloses an electronic compass based on a novel weak magnetic sensor, which comprises the following components: the novel weak magnetic sensor of triaxial (1), acceleration sensor (2), signal conditioning and collection module (3), microprocessor (4), set/module (5) that resets, display module (6), data interface module (7), power (8). The novel triaxial weak magnetic sensor (1) adopts a giant magnetic effect magnetic probe, namely: the magnetic probe is made of soft magnetic alloy material, when high-frequency alternating current is conducted, the alternating current impedance at two ends of the material is changed remarkably along with the change of an axially external magnetic field, and meanwhile, the effective magnetic conductivity of the soft magnetic alloy material is changed along with the comprehensive action of the external magnetic field, the alternating current driving field, the magnetic moment orientation in the magnetic material and the magnetic structure. The electronic compass of the giant magnetic effect magnetic probe sensor has the advantages of high frequency response speed, miniaturization, low power consumption, no magnetic hysteresis, high precision, strong anti-interference capability and the like.
Description
Technical Field
The utility model is applied to the technical field of electronic compasses, in particular to the technical field of weak magnetic sensors applied to the electronic compasses.
Background
Electronic compasses, also known as digital compasses, have significant advantages over the navigation approaches described above. Electronic compasses use a method of combining navigational orientations. The electronic compass can ensure that the navigation orientation information is 100% effective, because the electronic compass can effectively compensate the GPS signal. The device can ensure that the instrument can work normally when the GPS signal is unlocked, thereby achieving the purpose of 'losing stars and not losing directions'. The electronic compass has the advantages of small volume, light weight, miniaturization and the like, and the output electric signal can realize digital display through processing, thereby realizing pointing; with the development of sensitive component technology, the component technology required for designing the electronic compass becomes mature day by day, which has great advantages for the development technology of the electronic compass.
The electronic compass has problems in use: the magnetic field intensity of the geomagnetic field is about 0.6 gauss, the geomagnetic sensor belongs to the field of weak magnetism, and the requirement on the measurement accuracy of the magnetic sensor is high; the interference of the magnetic material on the electronic compass carrier to the geomagnetic field can seriously affect the measurement accuracy of the electronic compass, and the interference cannot be completely avoided;
since the magnetic field measuring materials used for the electronic compass are different, the electronic compass is mainly classified into three types: fluxgate sensor type, hall effect sensor type, and magnetoresistive sensor type. The peripheral circuit of the fluxgate sensor type electronic compass is complex in design, the size is difficult to reduce, and the requirement of portability during traveling cannot be met; the signal output linearity of the Hall effect sensor type electronic compass is poor, the Hall effect sensor type electronic compass is easy to be influenced by temperature, and the precision of the Hall effect sensor type electronic compass is easy to be influenced outdoors.
In order to solve the problems, a magnetoresistive sensor type electronic compass based on a magnetoresistive effect can be adopted, and compared with the domestic research, the domestic research is more disadvantaged, and the currently developed electronic compass is not sufficient in combination of precision, anti-interference performance and cost performance, so that the common development of the three can not be well realized.
SUMMERY OF THE UTILITY MODEL
Aiming at the technical problems, the utility model applies the weak magnetic sensor to the technical field of electronic compass, and the specific technical scheme is as follows:
an electronic compass based on a novel weak magnetic sensor comprises the following components: the novel weak magnetism sensor of triaxial 1, acceleration sensor 2, signal conditioning and collection module 3, microprocessor 4, set/module 5 that resets, display module 6, data interface module 7, power 8, the novel weak magnetism sensor of triaxial 1 adopts giant magnetic effect magnetic probe, promptly: the magnetic probe is made of soft magnetic alloy material, when high-frequency alternating current is conducted, the alternating current impedance at two ends of the material is changed remarkably along with the change of an axially external magnetic field, and meanwhile, the effective magnetic conductivity of the soft magnetic alloy material is changed along with the comprehensive action of the external magnetic field, the alternating current driving field, the magnetic moment orientation in the magnetic material and the magnetic structure.
The giant magnetic effect magnetic probe is divided into 4 types: the magnetic probe comprises a circumferential driving giant magnetic effect magnetic probe, a longitudinal driving giant magnetic effect magnetic probe, an off-diagonal giant magnetic effect magnetic probe and a coil driving giant magnetic effect magnetic probe.
The power supply 8 firstly reduces the voltage to 5V through the MC34063 chip, and then converts the 5V voltage output by the MC34063 chip into 3.3V by adopting the AMS1117 chip.
An inductor, a diode, a plurality of filter capacitors and two divider resistors are required to be connected to the periphery of the MC34063 chip to form a switching power supply system.
The display module 6 adopts an LCD1602 integrated display module to display, and all pins except a power supply pin and a brightness adjusting pin are directly connected with a general input/output interface of an STM32F103C8 chip.
The utility model has the technical effects that: the giant magnetic effect is a form of electromagnetic effect. In addition, the giant magnetic effect magnetic probe sensor has the advantages of high frequency response speed, miniaturization, low power consumption, no magnetic hysteresis and the like, so that the giant magnetic effect magnetic probe sensor has important application prospects in the fields of weak magnetic field measurement, geomagnetic navigation, high-density information storage, nondestructive testing, biological testing, stress sensing and the like. With the rapid development of electronic technology, the novel electronic compass is widely applied to the fields of spaceflight, navigation, geographical mapping, biomedical treatment and the like with the advantages of high precision, rapid response, strong anti-interference capability and the like.
Drawings
FIG. 1 is a composition diagram of an electronic compass system based on a novel weak magnetic sensor.
FIG. 2 is a diagram of a giant magnetic effect magnetic probe.
Fig. 3 power supply circuit diagram.
FIG. 4 is a circuit diagram of a data interface module.
FIG. 5 is a sensor interface circuit diagram.
Fig. 6 shows the circuit of the module.
In the figure: the sensor is characterized in that the sensor is a triaxial novel weak magnetic sensor, 2 is an acceleration sensor, 3 is a signal conditioning and acquisition module, 4 is a microprocessor, 5 is a setting/resetting module, 6 is a display module, 7 is a data interface module, and 8 is a power supply.
Detailed Description
The following further describes the embodiments of the present invention with reference to the drawings.
1. General scheme
1) An electronic compass based on a novel weak magnetic sensor comprises the following components: the novel weak magnetism sensor of triaxial 1, acceleration sensor 2, signal conditioning and collection module 3, microprocessor 4, set/module 5 that resets, display module 6, data interface module 7, power 8, the novel weak magnetism sensor of triaxial 1 adopts giant magnetic effect magnetic probe, promptly: the magnetic probe is made of soft magnetic alloy material, when high-frequency alternating current is conducted, the alternating current impedance at two ends of the material is changed remarkably along with the change of an axially external magnetic field, and meanwhile, the effective magnetic conductivity of the soft magnetic alloy material is changed along with the comprehensive action of the external magnetic field, the alternating current driving field, the magnetic moment orientation in the magnetic material and the magnetic structure. As shown in fig. 1.
2) The giant magnetic effect magnetic probe is divided into 4 types: the magnetic probe comprises a circumferential driving giant magnetic effect magnetic probe, a longitudinal driving giant magnetic effect magnetic probe, an off-diagonal giant magnetic effect magnetic probe and a coil driving giant magnetic effect magnetic probe. As shown in fig. 2.
3) The power supply 8 firstly reduces the voltage to 5V through the MC34063 chip, and then converts the 5V voltage output by the MC34063 chip into 3.3V by adopting the AMS1117 chip. As shown in fig. 3.
4) An inductor, a diode, a plurality of filter capacitors and two divider resistors are required to be connected to the periphery of the MC34063 chip to form a switching power supply system.
5) The display module 6 adopts an LCD1602 integrated display module to display, and all pins except the power supply pin and the brightness adjusting pin are directly connected with the general input/output interface of the STM32F103C8 chip. As shown in fig. 6.
2. Driving mode of giant magnetic effect magnetic probe
2.1 toroidal drive
By means of micro spot welding (to avoid high temperature welding affecting the magnetic domain structure of the material), the amorphous wire and the conducting wire are welded together and fixed by conductive adhesive, and then alternating current is energized to the material, and the generated magnetic field is along the annular direction of the amorphous wire, so that the material is called annular driving (or annular excitation). The circumferential driving GMI effect shows different rules with different frequencies of the excitation current, and is related to the magnetic structure of the material and the magnetization behavior under the circumferential magnetic field generated by the excitation current. When the frequency of the exciting current is higher, the impedance of the material is expressed as a function of the circumferential permeability by the skin effect, and the circumferential permeability can be changed by a smaller axial external magnetic field, so that the impedance of the material is changed. In the dynamic magnetization process of the material, domain wall movement plays a main role when the excitation frequency is low, magnetic domain rotation plays a main role when the frequency is high, and an axial external magnetic field has different influences on the two magnetization processes, so that the giant magneto-impedance effect of the amorphous material is closely related to the frequency of the excitation current.
2.2 longitudinal drive
When an excitation coil surrounding an amorphous material is energized with an alternating current of a certain frequency, the magnetic field generated by the excitation coil is along the axial direction (or longitudinal direction) of the amorphous material, and is called longitudinal driving (or longitudinal excitation). The amorphous material and the coil are equivalent to form an impedance element, alternating current introduced into the coil can generate a longitudinal driving magnetization field on the amorphous material, and when an external axial magnetic field exists, obvious impedance change, namely a longitudinal driving giant magneto-impedance effect, can be observed. Furthermore, the longitudinal drive GMI effect is related to the coil inner diameter, the smaller the coil inner diameter, the larger the change in impedance, and the higher the sensitivity.
2.3 off diagonal drive
The non-diagonal driving refers to a driving mode in which a driving current end and a pickup signal end are different, so that both the circumferential driving and the longitudinal driving can be called diagonal driving. The variation curve of the impedance of the diagonal driving mode with the external magnetic field is symmetrical about the longitudinal axis, while the variation curve of the impedance of the non-diagonal driving mode is asymmetrical and is only approximately linear in a certain specific interval, so that the bias current or the bias magnetic field is necessary for the non-diagonal driving mode. If the excitation current is sine wave and no bias exists, the off-diagonal magnetic impedance has small change effect and unobvious regularity; if square wave pulse current excitation is adopted, under the condition of not using bias, a remarkable off-diagonal magnetic impedance effect can be generated.
2.4 drive mode comparison
The circumferential driving mode is simple in design, while the longitudinal driving mode is complicated due to the additional coil. However, the alternating current of the longitudinal driving method does not directly pass through the hypersensitive material, and joule heat loss of the material itself and contact resistance of the lead wire can be avoided. The impedance profile of the off-diagonal drive is asymmetric, and usually requires the application of a bias current or a bias magnetic field.
3. Hardware circuit design
The central processor module is mainly an STM32F103C8 chip; the sensor module consists of two chips, namely a triaxial weak magnetic sensor HMC5883L and a triaxial acceleration sensor AXDL345, and transmits measurement data to an STM32F103C8 by adopting an IIC serial port data bus; the display module adopts an LCD1602 liquid crystal display screen to display the measurement angle in a digital form, and the STM32F103C8 drives the LCD1602 liquid crystal display screen through a GPIO interface; the data transmission interface module takes a CH340 chip as a core, and the chip mainly has the function of converting the USART format communication data into USB format data; the power module mainly comprises an MC34063 chip and an LM1117 chip, wherein the MC34063 chip converts the voltage of a 12V lithium battery into 5V voltage required by the display module and the data transmission interface module, and the LM1117 chip converts the 5V voltage output by the MC34063 chip into 3.3V voltage values required by the central processing unit module and the sensor module; meanwhile, considering that the storage module mainly stores programs and interference compensation parameters, the programs of the electronic compass occupy about 10KB of storage space, the storage space occupied by the interference compensation parameters is less than 1KB, and the STM32F103C8 chip is internally provided with 64KB of FLASH, so that about 53KB of storage space is still available, because the measurement data of one group of single-axis sensors needs 2Byte storage space, the measurement data at one time needs 12Byte storage space, and the STM32F103C8 chip can store 4416 groups of measurement data, thereby meeting the requirement of the electronic compass on the storage space.
3.1 sensor interface Circuit
As shown in fig. 5, which is a circuit design diagram of a sensor module, a triaxial weak magnetic sensor HMC5883L chip and a triaxial acceleration sensor ADXL345 chip jointly form the sensor module of an electronic compass, the two sensor chips are powered by low-voltage 3.3V direct-current voltage, and both chips provide IIC serial data bus interfaces (SDA and SCL pins), so that the sensor module can conveniently communicate with an STM32F103C8 chip. The HMC5883L chip and the ADXL345 chip share a set of IIC serial data buses, and the other ends of the buses are connected to pins 21 (IIC2_ SCL and PB10 multiplex) and 22 (IIC2_ SCL and PB11 multiplex) of the STM32F103C8 chip.
3.2 Power supply Circuit
As shown in fig. 3, an inductor, a diode, a plurality of filter capacitors, and two voltage dividing resistors are connected to the periphery of the MC34063 chip to form a switching power supply system. According to the internal structure diagram of the MC34063 chip, the value of the output voltage is determined by the ratio of R2 and R3, and the value of the output voltage is calculated according to an analysis circuit. And the AMS1117 chip can realize the level conversion function by adding two filter capacitors at the periphery.
3.3. Data interface module circuit
The data transmission module mainly completes data transmission and program programming tasks of the central processing unit and the upper computer. As shown in fig. 4, the data transmission module is composed of a CH340T chip, a 12MHz crystal oscillator and a plurality of capacitors, the CH340T chip exchanges data with the STM32F103C8 chip through USART serial ports (pin TXD and pin RXD), and the CH340T chip exchanges data with the upper computer through USB serial ports (pin UD and pin UD).
3.4. Display module circuit
As shown in fig. 6, the present design uses an LCD1602 integrated display module for display, all pins except the power supply pins (VSS and VCC, BLA and BLK) and the brightness adjustment pin (V0) are directly connected to the GPIO of the STM32F103C8 chip. Considering that the LCD1602 integrated display module is 5V level powered and the STM32F103C8 chip is 3.3V level powered, there is a problem of interface level mismatch.
Claims (5)
1. An electronic compass based on a novel weak magnetic sensor comprises the following components: novel weak magnetic sensor of triaxial (1), acceleration sensor (2), signal conditioning and collection module (3), microprocessor (4), set/module (5) that resets, display module (6), data interface module (7), power (8), its characterized in that: the novel triaxial weak magnetic sensor (1) adopts a giant magnetic effect magnetic probe, namely: the magnetic probe is made of soft magnetic alloy material, when high-frequency alternating current is conducted, the alternating current impedance at two ends of the material is changed remarkably along with the change of an axially external magnetic field, and meanwhile, the effective magnetic conductivity of the soft magnetic alloy material is changed along with the comprehensive action of the external magnetic field, the alternating current driving field, the magnetic moment orientation in the magnetic material and the magnetic structure.
2. The novel weak magnetic sensor-based electronic compass according to claim 1, characterized in that: the giant magnetic effect magnetic probe is divided into 4 types: the magnetic probe comprises a circumferential driving giant magnetic effect magnetic probe, a longitudinal driving giant magnetic effect magnetic probe, an off-diagonal giant magnetic effect magnetic probe and a coil driving giant magnetic effect magnetic probe.
3. The novel weak magnetic sensor-based electronic compass according to claim 1, characterized in that: the power supply (8) firstly reduces the voltage to 5V through the MC34063 chip, and then converts the 5V voltage output by the MC34063 chip into 3.3V by adopting the AMS1117 chip.
4. The novel weak magnetic sensor-based electronic compass according to claim 3, characterized in that: an inductor, a diode, a plurality of filter capacitors and two divider resistors are required to be connected to the periphery of the MC34063 chip to form a switching power supply system.
5. The novel weak magnetic sensor-based electronic compass according to claim 1, characterized in that: the display module (6) adopts an LCD1602 integrated display module to display, and all pins except a power supply pin and a brightness adjusting pin are directly connected with a general input/output interface of an STM32F103C8 chip.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202121352752.6U CN215865238U (en) | 2021-06-17 | 2021-06-17 | Electronic compass based on novel weak magnetic sensor |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202121352752.6U CN215865238U (en) | 2021-06-17 | 2021-06-17 | Electronic compass based on novel weak magnetic sensor |
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| CN215865238U true CN215865238U (en) | 2022-02-18 |
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| CN202121352752.6U Expired - Fee Related CN215865238U (en) | 2021-06-17 | 2021-06-17 | Electronic compass based on novel weak magnetic sensor |
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