CN-122015938-A - Magnetic sensor calibration method

Abstract

The invention discloses a magnetic sensor calibration method, which is characterized in that the calibration efficiency is obviously improved, and relates to the technical field of magnetic sensor calibration. The calibration precision is guaranteed, the sensitivity matrix and the zero offset parameter can be accurately calculated by accurately controlling the magnetic field of the Helmholtz coil and the angle of the rotating platform and combining a reasonable error model, and the precision requirement of most application scenes is met. The system has a simplified structure, only rotation control of two specific positions is needed, a complex three-dimensional rotation mechanism is not needed, and the system cost and the maintenance difficulty are reduced.

Inventors

• YANG FENG
• JIN XIAOHUA
• YU PENG
• WANG YONG

Assignees

• 艾瑞迈迪医疗科技（北京）有限公司

Dates

Publication Date

20260512

Application Date

20260225

Claims (10)

1. 1. A method for calibrating a magnetic sensor, comprising: Fixing a magnetic sensor to be calibrated on a non-magnetic rotating platform at the center of a Helmholtz coil; Controlling the Helmholtz coil to apply a constant current to generate a uniform magnetic field with target strength and target direction; rotating the magnetic sensor to be calibrated to a first calibration position by using the non-magnetic rotating platform, and measuring and recording first output data of the magnetic sensor to be calibrated; Rotating the magnetic sensor to be calibrated to a second calibration position which has a phase difference with the first calibration position by utilizing the non-magnetic rotating platform, and measuring and recording second output data of the magnetic sensor to be calibrated; and calculating and obtaining calibration parameters of the magnetic sensor to be calibrated by using the first output data and the second output data based on a preset magnetic sensor error model.
2. 2. The method of calibrating a magnetic sensor according to claim 1, wherein the phase difference between the first calibration position and the second calibration position is 90 °.
3. 3. The method for calibrating a magnetic sensor according to claim 2, wherein the first calibration position is a position of 0 ° where a sensitive axis of the magnetic sensor to be calibrated is parallel to the direction of the uniform magnetic field, and the second calibration position is a position of 90 ° where the sensitive axis of the magnetic sensor to be calibrated is perpendicular to the direction of the uniform magnetic field.
4. 4. The method of calibrating a magnetic sensor according to claim 2, wherein the non-magnetic rotating platform comprises a stepper motor, a controller and a shielding housing, the stepper motor and the controller being configured to control the rotation angle to 0 ° and 90 °, the shielding housing being configured to shield external electromagnetic interference.
5. 5. The method of calibrating a magnetic sensor according to claim 1, wherein the calibration parameters include a sensitivity matrix and a zero offset vector.
6. 6. The method of calibrating a magnetic sensor according to claim 5, wherein the magnetic sensor error model is represented by: V = M B + V0 Wherein V represents a magnetic sensor output vector, B represents a magnetic field intensity vector, M represents a sensitivity matrix to be solved, and V0 represents a zero offset vector to be solved.
7. 7. The method for calibrating a magnetic sensor according to claim 6, wherein the method for solving a magnetic sensor error model comprises: setting the magnetic field intensity vector of the first calibration position as B1, setting the magnetic sensor output vector to be calibrated as V1, setting the magnetic field intensity vector of the second calibration position as B2, setting the magnetic sensor output vector to be calibrated as V2, and solving the equation set: V1 = M B1 + V0 V2 = M B2 + V0 And obtaining the sensitivity matrix M and the zero offset vector V0.
8. 8. The method according to claim 1, wherein a plurality of data acquisitions are performed at the first calibration position and the second calibration position, respectively, and the results of the plurality of acquisitions are averaged as output data of the position.
9. 9. The method of calibrating a magnetic sensor according to claim 1, wherein the uniform magnetic field generated by the helmholtz coil is monitored in real time through a fluxgate to ensure uniformity and stability of the magnetic field.
10. 10. The method for calibrating the magnetic sensor according to claim 1, further comprising a wireless communication module, wherein the magnetic sensor to be calibrated is in communication connection with a data acquisition module through the wireless communication module to realize wireless calibration, and the data acquisition module is used for acquiring output data of the magnetic sensor to be calibrated.

Description

Magnetic sensor calibration method Technical Field The invention relates to the technical field of magnetic sensor calibration, in particular to a magnetic sensor calibration method only requiring two specific positions. Background The magnetic sensor is widely applied to the fields of navigation, positioning, industrial detection, medical appliances and the like, and the measurement accuracy directly influences the performance of the whole system. Because of factors such as manufacturing process, material characteristics and the like, the magnetic sensor has the problems of inconsistent sensitivity, zero offset error, non-orthogonal error and the like, and the errors must be corrected through calibration, so that the measurement accuracy is improved. The conventional calibration method of the magnetic sensor generally needs to rotate the sensor in a three-dimensional space for a plurality of positions (such as a 6-position method, an 8-position method, a 24-position method and the like), collect a large amount of data, and fit calibration parameters through optimization algorithms such as a least square method and the like. The method needs to manually put or rotate the turntable to change the position or angle, the calibration process is tedious, the time consumption is long, the calibration accuracy is limited, and particularly for a mass production scene, the calibration efficiency becomes a production bottleneck. In the prior art, calibration systems based on helmholtz coils are widely used, which are capable of generating a uniform, controllable standard magnetic field. However, conventional methods still require multiple position measurements or other calibration devices to be used together, often requiring minutes or even longer to calibrate a sensor using multiple position measurements. And when used in combination with other calibration equipment, the complexity of the rotating mechanism and the like increases the cost and maintenance difficulty of the system. For example, patent document 202410348330.3 describes a magnetometer calibration device, which controls an ac power supply to drive a three-dimensional uniform magnetic field generating device to generate a uniform magnetic field with any direction and size in a three-dimensional space by a program, and replaces physical rotation of a magnetometer by automatic dynamic adjustment of the magnetic field direction, thereby normalizing and standardizing the magnetometer calibration flow. Compared with the traditional calibration method, the method can remarkably save time cost and greatly improve the feasibility applicable to practical engineering application. The closed-loop control system of the fluxgate meter is introduced into a control system of the alternating current power supply driving uniform magnetic field generating device, compared with the open-loop control, the closed-loop control system can monitor and correct magnetic field parameters in real time, and the stability and the accuracy of a magnetic field are ensured. In addition, the device has the advantages of simple structure, convenient assembly, low cost and the like. However, this solution requires the acquisition of "gold standard" as the magnetic field by means of a fluxgate meter, in order to be able to accurately judge the direction and intensity of the magnetic field generated by the coil. There are also disadvantages such as complicated hardware structure. Therefore, how to provide a magnetic sensor calibration method capable of remarkably improving calibration efficiency on the premise of ensuring calibration accuracy is a technical problem which needs to be solved by those skilled in the art. Disclosure of Invention In view of the above, the present invention provides a magnetic sensor calibration method for overcoming or at least partially solving the above problems. The method solves the problem of low efficiency of the existing magnetic sensor calibration method, and can complete calibration by only two positions, thereby greatly improving the calibration efficiency while ensuring the calibration precision. The invention provides the following scheme: A magnetic sensor calibration method comprising: Fixing a magnetic sensor to be calibrated on a non-magnetic rotating platform at the center of a Helmholtz coil; Controlling the Helmholtz coil to apply a constant current to generate a uniform magnetic field with target strength and target direction; rotating the magnetic sensor to be calibrated to a first calibration position by using the non-magnetic rotating platform, and measuring and recording first output data of the magnetic sensor to be calibrated; Rotating the magnetic sensor to be calibrated to a second calibration position which has a phase difference with the first calibration position by utilizing the non-magnetic rotating platform, and measuring and recording second output data of the magnetic sensor to be calibrated; and calculating and obtaining calibra