Electronic Compass plant

Key Points   Product: Electronic Compass (C9000-B and other variants)Features:• Utilizes three-dimensional magneto-resistive sensors for geomagnetic field measurement• Incorporates an accelerometer for static stability and inclination compensation• Uses Kalman filtering algorithm for noise reduction and optimal state estimation• Provides digital output signal for direct integration with control systemsAdvantages:• High accuracy and stability, suitable for dynamic environments• Low energy consumption, compact size, and lightweight• Anti-shaking and anti-vibration, ideal for aviation, robotics, autonomous vehicles, and navigation systems• Capable of compensating for hard and soft magnetic interference• Can be integrated into control loops for applications like autonomous navigation or equipment maintenance Electronic compasses, also called digital compasses, are a method of using the Earth's magnetic field to determine the North Pole, and have been widely used as navigation instruments or attitude sensors. In ancient times, it was called compass, and the magneto-resistance sensor produced by modern advanced processing technology provides a powerful help for the digitalization of compass. Nowadays, electronic compasses are generally machined from chips such as magneto-resistive sensors or fluxgates. It can be used in horizontal and vertical hole measurement, underwater exploration, aircraft navigation, scientific research, education and training, building positioning, equipment maintenance, navigation system and other fields.   Compared with the traditional pointer type and balance frame structure compass, the digital compass has low energy consumption, small size, light weight, high precision and miniaturization. Its output signal can be digitally displayed through processing. It can not only be used for pointing, but also the digital signal can be directly sent to the automatic rudder to control the ship's operation. At present, the three-axis strap-down magnetic resistance digital magnetic compass is widely used. This kind of compass has the advantages of anti-shaking and anti-vibration, high heading accuracy, electronic compensation for interference field, and can be integrated into the control loop for data link, so it is widely used in aviation, aerospace, robotics, navigation, vehicle autonomous navigation and other fields.   1.The constitution of an electronic compass The three-dimensional electronic compass C9000-B is composed of a three-dimensional reluctance sensor, an inclination sensor and an MCU. The 3D magneto-resistive sensor is used to measure the earth's magnetic field, and the inclination sensor is used to compensate the non-horizontal state of the magnetometer. The MCU processes signals from magnetometers and tilt sensors as well as data output and soft and hard iron compensation. The magnetometer is based on three vertical magneto-resistive sensors, each axial sensor detects the strength of the geomagnetic field in that direction.     The sensor in the forward direction called the x direction detects the vector value of the geomagnetic field in the x direction, and the sensor in the right or Y direction detects the vector value of the geomagnetic field in the Y direction. Sensors in the down or Z direction detect the vector value of the Earth's magnetic field in the Z direction.   The sensitivity of the sensors in each direction has been adjusted to the optimum point based on the component vector of the geomagnetic field in that direction and has very low cross-axis sensitivity. The analog output signal generated by the sensor is amplified and sent to MCU for processing.   2.The following part of the hardware and principles are introduced 1)Magnetometer: Since the geomagnetic field is a vector, at a certain point, this vector can be broken down into two components parallel to the local level and one component perpendicular to the local level. So if you keep the compass module parallel to the local level the three axes of the magnetometer correspond to these three components. At present, the module is parallel to the horizontal plane by the Angle compensation, and then the heading Angle is calculated by the compensated data.   2) Accelerometer: The acceleration can be calculated from the three-axis data, which has advantages in static stability.   3)Kalman filtering is an algorithm that optimally estimates the state of a system by using linear system state equation and observing system input and output data. Since the observation data includes the effects of noise and interference in the system, the optimal estimation can also be regarded as a filtering process.   In radar, for example, one is interested in tracking a target, but measurements of the target's position, speed, and acceleration are often noisy at all times. Kalman filter uses the dynamic information of the target, tries to remove the influence of noise, and gets a good estimate of the target position. This estimate can be an estimate of the current target location (filtering), an estimate of the future location (prediction), or an estimate of the past location (interpolation or smoothing).   Summary In addition to the three-axis electronic compass, Micro-Magic company has a wealth of electronic compass types, such as low-cost two-axis electronic compass C9000-B, high-precision two-axis electronic compass C9000-D, etc., they have been strictly tested, in extremely harsh environments can also provide accurate course data. If you have the need for digital compass, freely to contact us. C9000-B High-precision all attitude 3D electronic compass board using advanced hard and soft iron calibration algorithms digital output   C9000-D High Performance Heading Sensor for Antenna Tower Azimuth Finding Low Cost Azimuth Angle Sensor Measure Tower Heading Angle  

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