Electronic Compass manufacturer

Key Points Product: Electronic Compass Principle of Calibration: - Magnetic field ellipse fitting: Collect magnetic field data in all directions while rotating the device, calculate hard iron interference and soft iron interference parameters, and apply compensation to fit the magnetic field data into a sphere for improved accuracy. Calibration Methods: 1. Plane calibration: - XY plane calibration: Rotate the device in the XY plane to find the center point of the trajectory circle projected in that plane. - XZ plane calibration: Rotate the device in the XZ plane to obtain the trajectory circle of the Earth's magnetic field and calculate the magnetic field interference vector in 3D space. 2. Stereoscopic 8-shaped calibration: - Rotate the device in various directions in the air to collect sample points that fall on the surface of a sphere. Determine the center of the circle to determine the interference value and perform calibration. Calibration Steps: 1. Preparation of testing environment: - Stay away from interference sources. - Ensure horizontal placement and stable installation. 2. Enter calibration mode: - Manually trigger calibration through key combinations or software instructions. - Auto prompt calibration when magnetic field anomalies are detected. 3. Perform calibration operation: - Horizontal rotation (2D calibration): Slowly rotate the device around the vertical axis in a horizontal position. - Three-dimensional rotation (3D calibration): Rotate the device around the X, Y, and Z axes, covering at least 360° for each axis. 4. Verify the calibration results: - Compare the device readings with a known geographic direction. - Use software tools to observe directional stability and accuracy. - Repeat calibration if deviation exceeds the nominal error of the device. Advantages of Electronic Compass: - Real-time heading and attitude measurement. - Crucial navigation tool. - Improves directional accuracy through calibration. - Various calibration methods available. - Can be used in different applications and environments.   Electronic compass is an important navigation tool that can provide real-time heading and attitude of moving objects. Calibration of an electronic compass is a crucial step in ensuring the accuracy of its directional measurement.   1. Calibration principle of electronic compass The electronic compass determines direction by measuring the components of the geomagnetic field. The calibration process is actually "magnetic field ellipse fitting": a) Collect magnetic field data  in all directions when the device rotates. b) Generate compensation parameters by calculating hard iron interference (fixed offset) and soft iron interference (scaling and cross coupling) through algorithms. c) Automatically apply compensation during subsequent measurements to fit the magnetic field data into a sphere centered at the origin, improving directional accuracy.   2. Calibration method for electronic compass The calibration methods for electronic compasses mainly include two methods: planar calibration and three-dimensional 8-shaped calibration. (1) Plane calibration method For the calibration of the XY axis, the device equipped with a magnetic sensor will rotate on its own in the XY plane, which is equivalent to rotating the Earth's magnetic field vector around the normal passing point O(γx,γy) perpendicular to the XY plane. It represents the trajectory of the magnetic field vector projected in the XY plane during the rotation process. This can find the position of the center of the circle as (Xmax+Xmin)/2, (Ymax+Ymin)/2. Similarly, rotating the device in the XZ plane can obtain the trajectory circle of the Earth's magnetic field on the XZ plane, which can calculate the magnetic field interference vector γ (γx, γy, γz) in three-dimensional space. After calibration, the electronic compass can be used normally on the horizontal plane. However, due to the angle between the compass and the horizontal plane, this angle can affect the accuracy of the heading angle and requires tilt compensation through acceleration sensors. (2) Stereoscopic 8-shaped calibration method Usually, when a device with sensors rotates in various directions in the air, the spatial geometric structure composed of measured values is actually a sphere, and all sampling points fall on the surface of this sphere, as shown in the following figure.‌                a) Aerial rotation:  Use calibrated equipment to perform an 8-shaped movement in the air, aiming for the normal direction of the equipment to point towards all 8 quadrants of space. By obtaining sufficient sample points, the center O(γx,γy,γz) is determined, which is the size and direction of the fixed magnetic field interference vector. b) Sample point collection:  When rotating the device in various directions in the air, the spatial geometric structure composed of measurement values is actually a sphere, and all sampling points fall on the surface of this sphere. By using these sample points, the center of the circle can be determined to determine the hard magnetic interference value and perform calibration.   3. Calibration steps for electronic compass (1) Preparation of testing environment Ø Stay away from interference sources: Ensure that there are no large metal objects (such as iron cabinets, vehicles), motors, speakers, or other electromagnetic equipment within 3 meters of the calibration environment. Ø Horizontal placement: Use a level or built-in sensor to adjust to a horizontal state, ensuring that the measurement is based on the horizontal component of the geomagnetic field. Ø Fixed method: Avoid wearing metal watches or rings when holding the device; If it is an embedded device (such as a drone), ensure a stable installation. (2) Enter calibration mode a) Manual triggering: Refer to the product manual, common methods include: n Key combination (such as long pressing the power and function keys for 5 seconds). n Software instructions (select 'Calibrate Compass' through the accompanying app). b) Auto prompt: Some devices automatically prompt calibration when detecting magnetic field anomalies (such as continuously displaying "low precision").   (3) Perform calibration operation a) Horizontal rotation (2D calibration): n Slowly rotate the equipment around the vertical axis (Z-axis) and keep it horizontal. n Ensure uniform rotation speed (about 10 seconds/turn), complete at least 2 turns to cover all directions. b) Three-dimensional rotation (3D calibration, suitable for high-precision equipment): n Rotate around the X (roll), Y (pitch), and Z (yaw) axes in sequence, with each axis rotating at least 360 °. n Example action: After horizontal rotation, flip the device upright and then tilt it back and forth. (4) Verify the calibration results a) Direction comparison method: Point the device towards a known geographic direction (such as using a compass to determine true north) and check if the readings match. b) Software validation: Use map apps or professional tools (such as magnetic field analysis software) to observe directional stability and accuracy. c) Repeat calibration: If the deviation exceeds the nominal error of the equipment (such as ±3°), recalibration and environmental interference inspection are required.   C9-B High Precision CAN Protocol Output 2D Electronic Compass C9-A 40° Tilt Angle Compensation CAN Protocol Output 3D Electronic Compass C9-C High Precision Digital Output 2D Electronic Compass Single Board  

  Key PointsProduct: Error Compensation Method for Electronic Compass Features: Compensates for magnetic interference (hard and soft iron) Utilizes the least squares method for error correction Employs an eight-position measurement technique for precise calibration Advantages: High accuracy in heading measurement Suitable for UAVs, marine, and automotive applications Moderate computational load, effective in dynamic environments Electronic compass has its own unique advantages: the electronic compass itself is small in size, light in weight, the acquisition and solution of azimuth information is real-time, and the output digital signal can make it more direct and convenient in the subsequent use. At present, the development of digital compass sensor technology has been relatively mature, so that it has certain advantages in measurement accuracy and manufacturing cost. Because digital compass is widely used in practice, a large number of high-precision, low-cost electronic compass products suitable for large-scale industrialization need to be put into production.     In today's society, the design and research of navigation and orientation instruments have important value and significance. With the expansion of human exploration in the space field, the stability maintenance, tracking guidance and other functions of artificial satellites, space shuttles, missile weapon systems and various platforms all need the support of navigation orientation technology and corresponding attitude adjustment devices. To sum up, obtaining orientation information and realizing the corresponding attitude control play a fundamental role in various scientific research and engineering realization.   According to the characteristic that the geomagnetic field changes little in a certain time range, it can be considered that the geomagnetic information at the same place is fixed in a short time, and the azimuth information such as heading Angle and attitude Angle can be calculated by the electronic compass according to the geomagnetic intensity information measured.   1.The principle characteristics of the geomagnetic field   As the basic physical quantity of the earth, the geomagnetic field has a direct effect on the physical characteristics of electric and magnetic substances in the earth environment. The characteristics of the Earth magnetic vector field provide a basic coordinate system for azimuth information, and the use of geomagnetic information navigation is stable and reliable, without receiving external information, with good concealment. The geomagnetic field is generated from the structure of the earth itself. There are many magnetic elements and substances in the earth's interior, which produce free flowing electrons under the influence of the extreme environment inside the Earth. These free electrons lead to the improvement of the conductivity between the earth's inner core and outer core, resulting in the flow and movement of free electrons between different strata. This makes the earth as a whole have a stable magnetic field on a macro level, which is equivalent to a magnetic dipole with a constant magnetic field existing in the center of the Earth, resulting in the production of north and south magnetic poles. Figure 1 shows the schematic diagram of the distribution of the Earth's magnetic field. The unit of magnetic induction intensity is Tesla (T), which is Gaussian (Gs) in Gaussian units, and the corresponding relationship between the two is 1T=10-4Gs, the unit system of magnetic field intensity is A/m, and the unit system of magnetic field intensity is Oster (Oe) in Gaussian units, and the corresponding relationship between the two is 1A/m=4π*10-3Oe   The Earth's magnetic field can be classified into basic geomagnetic field, variable geomagnetic field and abnormal geomagnetic field according to the degree of stability. The basic magnetic field covers most of the magnetic field, accounting for more than 90% of the Earth's total magnetic field. The basic type of geomagnetic field can also be divided into dipole-induced magnetic field and non-dipole-induced magnetic field, in which the dipole-induced effect accounts for the main part, the magnetic field comes from the circulation movement of iron and nickel under high temperature and high pressure environment, and the non-dipole is mainly generated by the self-excited motor effect. The basic geomagnetic field itself also changes, but the period of change is very long, so the Earth's magnetic field as a whole can be considered stable. The changing electromagnetic field is generated in the ionosphere and magnetosphere of the earth, and the magnetic field disturbance is mainly related to the solar change, and the changing electromagnetic field can be divided into stable change and interference change. Quiet changes occur on the solar or lunar calendar and are mainly caused by solar electromagnetic radiation or particle radiation. The phenomenon of magnetic storm is the phenomenon of geomagnetic interference in large space, the main effect of which is the strong change of the ground vector component of geomagnetic field. The abnormal geomagnetic field comes from the ferromagnetic properties of ferromagnetic materials and can be regarded as the constant vector addition on the stable geomagnetic field.   2.Error analysis of electronic compass   Deviation of electronic compass, also known as compass deviation, is the error of measurement results caused by ferromagnetic interference in the nearby environment when the compass is working. The deviation between the measurement results and the real value is even tens of degrees without corresponding compensation link, which is because the magnetic field strength of the earth magnetic field is weak, and the magnetic field strength is only 0.5-0.6 gauss. Therefore, the measurement results of digital compass are very easy to introduce the interference caused by environmental ferromagnetic factors, and the compass has become the main source of error of electronic compass.   Compass can also be divided into hard iron interference and soft iron interference, hard iron interference is caused by permanent magnetic objects or magnetized objects, with a permanent magnetic material under the influence of the external magnetic field, the overall magnetic moment of the object is no longer zero, thus showing magnetism. The magnetic field strength generated by it can be regarded as constant and unchanged in a certain time range, and this permanent magnetic material still maintains a relatively stable residual magnetic field strength after the magnetization effect, even after the external magnetic field action is removed. To sum up, the position and intensity of the interference effect on the compass can be considered as a fixed and constant stabilizing effect, and the compensation means for it is relatively easy to realize.   Summary     Micro-Magic company for aerospace, mining drilling and other engineering projects to provide tools and technical support, the current electronic compass series, C9000-A,C9000-B,C9000-C,C9000-D and other products, with soft magnetic, hard magnetic compensation function, it plays an important role in improving the north finding accuracy. If you want to understand the information of digital compass, you can always communicate with our professionals. C9000-A Tilt Compensated Magnetic Compass Sensor 3 Axis Magnetic Heading Yaw Angle Meter C9000-B High-precision all attitude 3D electronic compass board using advanced hard and soft iron calibration algorithms digital output C9000-C Fluxgate Compass Gyro Compensated Compass 6 Axis Compass Electronic Yaw Heading Sensor C9000-D High Performance Heading Sensor for Antenna Tower Azimuth Finding Low Cost Azimuth Angle Sensor Measure Tower Heading Angle  

  Key Points Product: Error Compensation Method for Electronic Compass Features: Compensates for magnetic interference (hard and soft iron) Uses least squares method for error correction Eight-position measurement for accurate calibration Advantages: High accuracy in heading measurement Suitable for UAVs, marine, and automotive use Moderate computation load, effective for dynamic environments Electronic compass (also known as digital compass), is through the measurement of the Earth's magnetic field to complete the course calculation, often as a GPS signal or network is not effective supplement. Based on its advantages of small size, low energy consumption, high precision and miniaturization, it is widely used in the field of magnetic heading measurement such as UAV, Marine and automobile. However, in use, the electronic compass also has its own inherent defects: easy to be affected by external magnetic field interference and error, which is the main reason for affecting its measurement accuracy and restricting its application, so it is very necessary to study the method of compensating the measurement error of the electronic compass.   At present, there are many methods to compensate measurement error. For example, the compensation coefficient method is mainly aimed at the dynamic interference during measurement, while the static interference compensation effect is little, and the application range is small. Another example is the adaptive compensation method, which requires the system to achieve high compensation accuracy in the case of linear or low-speed movement, if the system rotates faster, the measurement accuracy will be greatly affected, so the more demanding application scenario makes this method not extensive. At present, if only a single error compensation model is used to compensate the compass error, it can not meet the requirements of the measuring system. In this paper, an error compensation algorithm based on ellipse hypothesis is proposed, which integrates the principle of least squares. The algorithm can realize effective compensation for the measuring error of the electronic compass, and has the characteristics of moderate calculation and wide application. 1.Error analysis of magnetic heading system When the digital compass is installed in the carrier for magnetic heading measurement, its measurement error is caused by a variety of factors, which can be roughly divided into two categories: one is caused by the system's own structure, materials, assembly and other reasons, including compass, installation error, manufacturing error; The other is attitude signal error, although it does not belong to the heading measurement system itself, but it is involved in the calculation of heading parameters, will also cause measurement error. Because the compass error is the most difficult to control and has the greatest influence on the course accuracy, this paper mainly analyzes the compass error. The compass difference is mainly composed of the horizontal component of the hard iron magnetic field and the horizontal component of the soft iron magnetic field of the carrier. A large number of experimental studies show that the error caused by the hard ferromagnetic field on the moving carrier is a periodic error, which can be expressed by formula (1), and its rule is approximately sinusoidal curve; The error caused by the soft iron magnetic field can be expressed by formula (2), and the law changes with the change of the environmental magnetic field.   Where ϕi is the measurement of the heading Angle, and A, B, C, D, and E are error coefficients. Through the error analysis of the compass above, we can see that the total compass of the electronic compass should be the algebraic sum of the above errors. Therefore, combine formulas (1) and (2) to find the total difference ∆ϕ     2.Error compensation by least square method Least Squares (LS) can be used to find the best function match of data by minimizing the sum of squares of errors. It is easy to obtain unknown data and minimize the sum of squares of errors between it and the actual data. The least squares method can also be used for curve fitting and is often used for data optimization.   The least square method can optimize the data fitting in the sense of minimum square variance. It is a mathematical optimization method that can compensate the error caused by the magnetic field interference of the external environment. Under normal circumstances, the measurement error presents a certain periodicity, a more suitable fitting method can be used trigonometric function method, based on the mathematical model of Fourier function, and then corrected according to the heading parameters provided by the standard compass. The following is a brief introduction to the basic principles of least squares.   When a correspondence between two variables y and x needs to be determined based on observations, assuming that they are linear, y at time t can be expressed as:   Where H1,H2,... Hn is n unknown parameters to be determined, x1 (t), x2(t),... xt(t) is a known deterministic function, such as the sine and cosine function of t. Let's say at time t1,t2... tn makes m measurements of y and x, hoping that the variables y and x1 (t), x2(t),... xt(t) to estimate their values. Then formula (4) can be expressed in matrix form: Y =X*H   Using the least squares method, the least squares estimates of the error coefficients A, B, C, D and E shown in formula (3) are obtained from the known azimuth Angle measurement ϕi and azimuth Angle error ∆ϕ. The specific calculation steps are as follows: ① The eight-position error measurement method is adopted. Taking into account the number of samples, the amount of data calculation and the measurement accuracy, eight points with the same Angle interval within the range of heading Angle 360, such as 0, 45, 90, 135, 180, 225, 270 and 315, were taken to conduct heading error test, and 8 sets of data were obtained. ② The error coefficients A, B, C, D and E are obtained according to the principle of least squares. Through the previous analysis, when the error coefficients A, B, C, D and E are calculated by the least square method, the actual course of the carrier after error correction can be calculated by the calculation formula, and the specific research and analysis will not be done here.   3.Summary Micro-Magic company specializes in navigation products, in addition to the least method of error compensation, there are elliptic false method of error compensation and other compensation methods. In the research and development process of electronic compass, it has gradually mature technology and consolidated theoretical foundation. In addition to the continuous optimization of north finding accuracy, there are tilt compensation and other functions, if you are interested in our products, welcome to learn more about our low-cost 2D digital compass C9-C, and 40° tilt compensation - 3D digital compass C90-B and so on, you can contact our professional and technical staff at any time. C9-A High-precision 3 dimension electronic compass with advanced 3D compensation technology C9-B Modbus RTU mode two dimension (2D) electronic compass for unmanned aerial vehicles C9-C high-precision two-dimensional (2D) electronic compass single circuit board measuring azimuth angles from 0 to 360 deg C9-D High-Precision Two-Dimensional (2D) Electronic Compass Single Circuit Board Measuring Azimuth Angles From 0 To 360 Deg