A method of calibrating an angle sensor

Abstract

The application provides a kind of angle sensor calibration method, it is related to sensor technical field, comprising: step S1, the angle sensor to be calibrated is fixed on the rotary table, then control the angle sensor carries out shaft zero point calibration and saves zero point offset;Step S2, control the rotary table is rotated to at least one preset test angle from the preset horizontal zero point position in turn, and when the rotary table rotates to each test angle, control the angle sensor carries out sensitivity calibration according to the zero point offset and obtains the corresponding sensitivity after calibration of the test angle.It is beneficial to effectively reduce the time of calibration, greatly improve the efficiency of calibration, especially suitable for the efficiency improvement of batch calibration of angle sensor.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, and in particular to a calibration method for an angle sensor. Background Technology

[0002] Angle sensors use accelerometers to detect angles by measuring the gravitational component. However, each accelerometer has differences in zero point and sensitivity at the factory, as well as errors. These are key factors affecting sensor performance, so zero point and sensitivity calibration is necessary.

[0003] Existing methods for calibrating the sensitivity of angle sensors include: first, calibrating the axial zero point of the angle sensor; then, finding the corresponding axial zero point of the angle sensor using a turntable and recording the current angle of the turntable or clearing the turntable to zero; finally, starting from the axial zero point of the angle sensor, rotating the turntable to a set interval angle, and after the microcontroller unit of the angle sensor obtains the voltage value output by the built-in accelerometer, issuing a calibration command to calibrate and obtain the sensitivity.

[0004] However, this method is only applicable to the calibration of the sensitivity of a single angle sensor. Its efficiency drops significantly when calibrating multiple batches of angle sensors, mainly because:

[0005] 1. The turntable needs a certain amount of time to find the zero point of the angle sensor axis, especially for angle sensors with slow response, the time consumption is significantly increased, and the zeroing time is relatively slow;

[0006] 2. The zero point of the axis calibrated by each angle sensor is not the same on the turntable, and there are differences. In the case of batch calibration, this will cause the turntable to need to be adjusted by small angles multiple times at the zero point of the axis calibrated by the angle sensor, which will increase the calibration time. Summary of the Invention

[0007] To address the problems existing in the prior art, the present invention provides a calibration method for an angle sensor, wherein a turntable is pre-configured and rotates along a vertical plane, and the calibration method includes:

[0008] Step S1: Fix the angle sensor to be calibrated on the turntable, and then control the angle sensor to perform shaft zero-point calibration to obtain the zero-point offset and save it.

[0009] Step S2: Control the turntable to rotate sequentially from a preset horizontal zero point position to at least one preset test angle, and when the turntable rotates to each test angle, control the angle sensor to perform sensitivity calibration based on the zero point offset to obtain the calibrated sensitivity corresponding to the test angle.

[0010] Preferably, the shaft zero-point calibration includes the following steps:

[0011] Step S11: Adjust the turntable to the horizontal zero point position;

[0012] Step S12: Fix the angle sensor to be calibrated on the turntable in the horizontal direction, and control the angle sensor to read the first voltage value output by its own accelerometer.

[0013] Step S13: Control the turntable to rotate 180 degrees from the horizontal zero point position, and then control the angle sensor to read the second voltage value output by its own accelerometer;

[0014] In step S14, the angle sensor processes the first voltage value and the second voltage value to obtain the zero-point offset.

[0015] Preferably, in step S14, the angle sensor calculates the average value between the first voltage value and the second voltage value to obtain the zero-point offset voltage value.

[0016] Preferably, when the angle sensor is in the accelerometer's data writing-enabled state, it writes the zero-point offset voltage value as the zero-point offset into the accelerometer's register for storage, thereby setting the accelerometer to zero.

[0017] In step S2, when the turntable rotates to each test angle, the angle sensor is controlled to read the real-time voltage value output by its own accelerometer, and the calibrated sensitivity corresponding to the test angle is calculated based on the real-time voltage value and the zero-point offset voltage value.

[0018] Preferably, the calibrated sensitivity corresponding to each test angle is calculated according to the following formula:

[0019]

[0020] Among them, Sen(gap) n AD is used to represent the calibrated sensitivity at the nth test angle. n The gap is used to represent the real-time voltage value read at the nth test angle. n The nth test angle is represented by ADoffset, which represents the output value of the zero-point offset voltage value. The output value is 0 after the accelerometer is set to zero, and sen0 represents the theoretical axis zero-point sensitivity of the angle sensor.

[0021] Preferably, when the accelerometer of the angle sensor does not allow data writing, the zero-point offset includes a zero-point offset voltage value, which is stored in the microcontroller unit of the angle sensor; the microcontroller unit also stores the theoretical axis zero-point sensitivity of the angle sensor.

[0022] In step S2, when the turntable rotates to each of the test angles, the angle sensor is controlled to read the real-time voltage value output by its own accelerometer, and the calibrated sensitivity corresponding to the test angle is calculated based on the real-time voltage value, the zero-point offset voltage value, and the theoretical axis zero-point sensitivity.

[0023] Preferably, the calibrated sensitivity corresponding to each test angle is calculated according to the following formula:

[0024]

[0025] Among them, Sen(gap) n AD is used to represent the calibrated sensitivity at the nth test angle. n The gap is used to represent the real-time voltage value read at the nth test angle. n The nth test angle is represented by ADoffset, which represents the output value of the zero-point offset voltage, and sen0 represents the theoretical axis zero-point sensitivity of the angle sensor.

[0026] Preferably, when the accelerometer of the angle sensor does not allow data to be written;

[0027] In step S14, the zero-point offset angle value is obtained by processing the zero-point offset voltage value and the pre-acquired theoretical axis zero-point sensitivity. The zero-point offset angle value is used as the zero-point offset amount and saved to the microcontroller unit of the angle sensor.

[0028] Preferably, the formula for calculating the zero-point offset angle value is as follows:

[0029]

[0030] Wherein, Angle(start) represents the zero-point offset angle value, ADoffset represents the output value of the zero-point offset voltage value, and sen0 represents the theoretical axis zero-point sensitivity.

[0031] Preferably, in step S2, when the turntable rotates to each test angle, the angle sensor is controlled to read the real-time voltage value output by its own accelerometer, and the calibrated sensitivity corresponding to the test angle is calculated based on the real-time voltage value and the zero-point offset angle value. Then:

[0032]

[0033] Among them, Sen(gap) nAD is used to represent the calibrated sensitivity at the nth test angle. n The gap is used to represent the real-time voltage value read at the nth test angle. n Angle(start) is used to represent the nth test angle, and Angle(start) is used to represent the zero-point offset angle value.

[0034] The above technical solution has the following advantages or beneficial effects:

[0035] 1) After the angle sensor performs shaft zero-point calibration to obtain its own zero-point offset, it saves the zero-point offset and uses it in the calculation when performing sensitivity calibration. This eliminates the need to control the turntable to find the shaft zero point of each angle sensor before performing batch sensitivity calibration, effectively reducing calibration time and greatly improving calibration efficiency. It is especially suitable for improving the efficiency of batch calibration of angle sensors.

[0036] 2) When performing shaft zero-point calibration, the zero-point offset is calculated by reading the voltage values ​​of the accelerometer of the angle sensor in the horizontal positive and horizontal negative directions, which effectively improves the calibration accuracy of the shaft zero point.

[0037] 3) Different angle offset storage methods are provided for angle sensors to meet the calibration requirements of different angle sensors and improve the applicability of the calibration method of the present invention, depending on whether the angle sensor allows data writing;

[0038] 4) No changes or revisions to the current automatic calibration system software are required, saving manpower and resources and reducing costs. Attached Figure Description

[0039] Figure 1 This is a flowchart illustrating a calibration method for an angle sensor in Example 1.

[0040] Figure 2 This is a flowchart illustrating the shaft zero-point calibration process in Example 1.

[0041] Figure 3 This is a schematic diagram of the angle sensor fixed horizontally on the turntable in Example 1;

[0042] Figure 4 This is a schematic diagram of the structure in Example 1, showing the angle sensor fixed on the turntable after it has rotated 180 degrees from the horizontal zero point position. Detailed Implementation

[0043] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The present invention is not limited to this embodiment; other embodiments that conform to the spirit of the present invention may also fall within the scope of the present invention.

[0044] Example 1

[0045] In this embodiment, based on the aforementioned problems existing in the prior art, a calibration method for an angle sensor is provided, wherein a turntable is pre-configured, and the turntable rotates along a vertical plane, as follows: Figure 1 As shown, the calibration method includes:

[0046] Step S1: Fix multiple angle sensors to be calibrated in batches onto the turntable, then control the angle sensors to perform shaft zero-point calibration to obtain the zero-point offset and save it.

[0047] Step S2: Control the turntable to rotate sequentially from the preset horizontal zero point position to at least one preset test angle, and when the turntable rotates to each test angle, control the angle sensor to perform sensitivity calibration based on the zero point offset to obtain the calibrated sensitivity corresponding to the test angle.

[0048] In a preferred embodiment, the turntable can be fixed to a support surface, which is a vertical plane. A rotating shaft extending horizontally is disposed on the support surface, with one end of the rotating shaft connected to the center of the turntable. A drive device for driving the rotating shaft can be correspondingly disposed on the support surface, allowing the turntable to rotate in the vertical plane under the drive of the drive device. This enables the angle sensor, when fixed on the turntable, to measure the gravitational component using its built-in accelerometer, thus performing calibration. It should be noted that the connection structure between the support surface, rotating shaft, drive device, and turntable is not limited and is not the inventive point of this technical solution. Existing drive connection structures can be used to achieve rotation of the turntable in the vertical plane.

[0049] Furthermore, after the angle sensor performs axis zero-point calibration to obtain its own zero-point offset, it saves the offset and incorporates it into the calculation during sensitivity calibration. This eliminates the need to control the turntable to find the axis zero of the angle sensor before sensitivity calibration, effectively reducing calibration time and making it particularly suitable for improving the efficiency of batch calibration of angle sensors.

[0050] In this embodiment, as Figure 2 As shown, shaft zero-point calibration includes the following steps:

[0051] Step S11: Adjust the turntable to the horizontal zero point position;

[0052] Step S12: Fix the angle sensor to be calibrated on the turntable in the horizontal direction, and control the angle sensor to read the first voltage value output by its own accelerometer.

[0053] Step S13: Control the turntable to rotate 180 degrees from the horizontal zero point position, and then control the angle sensor to read the second voltage value output by its own accelerometer;

[0054] In step S14, the angle sensor processes the first voltage value and the second voltage value to obtain the zero offset.

[0055] Specifically, in this embodiment, as Figure 3 As shown, during shaft zero-point calibration, the turntable 1 is first adjusted to the horizontal zero-point position (absolute horizontal position, i.e., the turntable 1 is parallel to the support surface 100). Then, the angle sensor 2 to be calibrated is fixed horizontally onto the turntable 1. This angle sensor 2 is connected to an external host computer via a communication cable 3, so as... Figure 3 In the diagram, the communication cable 3 faces right as the horizontal positive direction. After installation and fixation, the host computer can send a data acquisition command to the microcontroller unit in the angle sensor 2 to control the microcontroller unit of the angle sensor 2 to read the first voltage value output by its accelerometer in the horizontal positive direction. Subsequently, the host computer communicates with the turntable 1 and controls the turntable 1 to rotate 180 degrees clockwise, which is equivalent to flipping the angle sensor 2, so that the angle sensor is located as shown in the diagram. Figure 4 As shown in the figure, the direction of the current communication cable 3 to the left is taken as the horizontal reverse direction. At this time, the host computer sends a collection command to the microcontroller of the angle sensor 2 again to control the microcontroller of the angle sensor 2 to read the second voltage value output by its own accelerometer in the horizontal reverse direction. Then, the microcontroller can process the first voltage value and the second voltage value to obtain the zero point offset of the angle sensor.

[0056] Preferably, the zero-point offset angle values ​​obtained by the multiple angle sensors after the above-mentioned axis zero-point calibration are not exactly the same. For example, the zero-point offset angle value Angle(start) of angle sensor #6001 is 0.5°, and the zero-point offset voltage value ADoffset is 100; the zero-point offset angle value Angle(start) of angle sensor #6002 is 0.7°, and the zero-point offset voltage value ADoffset is 150. Therefore, after axis zero-point calibration, the zero-point offset value is also saved so that it can be used in the calculation during subsequent sensitivity calibration, thus eliminating the need for small-angle zeroing operation of the turntable for the zero-point offset angle value of each angle sensor.

[0057] In a preferred embodiment, multiple angle sensors 2 can be fixed on the turntable 1 at one time. The host computer can send acquisition commands to each angle sensor 2 in batches to realize batch axis zero-point calibration of each angle sensor 2 and obtain their respective zero-point offset.

[0058] Furthermore, in this embodiment, in step S14, the angle sensor calculates the average value between the first voltage value and the second voltage value to obtain the zero-point offset voltage value.

[0059] Specifically, when the angle sensor is in the accelerometer's data writing-enabled state, it writes the zero-point offset voltage value as the zero-point offset into the accelerometer's register for storage, thereby setting the accelerometer to zero.

[0060] In step S2, when the turntable rotates to each test angle, the control angle sensor reads the real-time voltage value output by its own accelerometer, and calculates the calibrated sensitivity corresponding to the test angle based on the real-time voltage value and the zero-point offset voltage value.

[0061] Specifically, the calibrated sensitivity for each test angle is calculated using the following formula:

[0062]

[0063] Among them, Sen(gap) n AD is used to represent the calibrated sensitivity at the nth test angle. n Used to represent the real-time voltage value read at the nth test angle, gap n The nth test angle is represented by ADoffset, which represents the output value of the zero-point offset voltage. The output value is 0 after the accelerometer is set to zero. sen0 represents the theoretical axis zero-point sensitivity of the angle sensor.

[0064] Specifically, the above test angles can be 10°, 20°, 30°, etc., and can be customized according to actual needs.

[0065] In this embodiment, when the accelerometer of the angle sensor allows data writing, after writing the zero-point offset voltage value into the accelerometer's register, the angle sensor also includes self-calibration based on the written zero-point offset voltage value, and after the self-calibration is completed, the zero-point offset voltage value is set to zero, that is, the value of ADoffset mentioned above is 0. In other words, at this time, the calculation formula for the calibrated sensitivity corresponding to each test angle is equivalent to the following formula:

[0066]

[0067] Example 2

[0068] In this embodiment, the axis zero-point calibration process is the same as in embodiment 1. The difference is that the accelerometer of the angle sensor does not allow data to be written. At this time, the zero-point offset voltage value, which is the zero-point offset, is saved in the microcontroller unit of the angle sensor. The microcontroller unit also stores the theoretical axis zero-point sensitivity of the angle sensor.

[0069] In step S2, when the turntable rotates to each test angle, the control angle sensor reads the real-time voltage value output by its own accelerometer, and calculates the calibrated sensitivity corresponding to the test angle based on the real-time voltage value, the zero-point offset voltage value, and the theoretical axis zero-point sensitivity.

[0070] Specifically, the theoretical zero-point sensitivity of the aforementioned axis is the theoretical sensitivity value of the corresponding angle sensor at 0g acceleration. This theoretical sensitivity value is the factory calibration value and can be obtained by consulting the product specification sheet of the angle sensor.

[0071] Specifically, the calibrated sensitivity for each test angle is calculated using the following formula:

[0072]

[0073] Among them, Sen(gap) n AD is used to represent the calibrated sensitivity at the nth test angle. n Used to represent the real-time voltage value read at the nth test angle, gap n The nth test angle is represented by ADoffset, which represents the output value of the zero-point offset voltage, and sen0 represents the theoretical axis zero-point sensitivity of the angle sensor.

[0074] Specifically, this embodiment is also applicable to the calibration of angle sensors where the registers of accelerometers are lost due to power failure. The zero-point offset voltage value obtained from the axis zero-point calibration is saved to the microcontroller unit of the angle sensor. At this time, ADoffset is the zero-point offset voltage value obtained from the axis zero-point calibration. The above test angles can be 10°, 20°, 30°, etc., and can be customized according to actual needs.

[0075] Example 3

[0076] In this embodiment, the process of zero-point calibration of the shaft is the same as in embodiment 1, except that the accelerometer of the angle sensor does not allow data to be written.

[0077] In step S14, the zero-point offset angle value is obtained by processing the zero-point offset voltage value and the pre-acquired theoretical axis zero-point sensitivity. The zero-point offset angle value is used as the zero-point offset amount and saved to the microcontroller unit of the angle sensor.

[0078] The formula for calculating the zero-point offset angle is as follows:

[0079]

[0080] Where Angle(start) represents the zero-point offset angle value, ADoffset represents the output value of the zero-point offset voltage value, and sen0 represents the theoretical axis zero-point sensitivity.

[0081] Furthermore, in step S2, when the turntable rotates to each test angle, the control angle sensor reads the real-time voltage value output by its own accelerometer, and calculates the calibrated sensitivity corresponding to the test angle based on the real-time voltage value and the zero-point offset angle value.

[0082] Specifically, the calibrated sensitivity is calculated using the following formula:

[0083]

[0084] Among them, Sen(gap) n AD is used to represent the calibrated sensitivity at the nth test angle. n Used to represent the real-time voltage value read at the nth test angle, gap n Angle(start) is used to represent the nth test angle, and Angle(start) is used to represent the zero-point offset angle value.

[0085] Specifically, this embodiment applies to situations where accelerometers, including but not limited to angle sensors, lack registers, or where registers are inconvenient to use or their data is lost upon power failure. The aforementioned test angles can be 10°, 20°, 30°, etc., and can be customized according to actual needs.

[0086] In summary, it can be seen that this technical solution provides a suitable storage method for zero-point offset and a corresponding sensitivity calibration method for different types of angle sensors. The zero-point offset includes the zero-point offset voltage value and the zero-point offset angle value. The zero-point offset angle value can be obtained by performing an arcsine operation on the zero-point offset voltage value and the theoretical axis zero-point sensitivity. When saving, it can be selected according to the performance of the angle sensor, such as saving only the zero-point offset voltage value in Example 1, or saving both the zero-point offset voltage value and the theoretical axis zero-point sensitivity in Example 2, or saving only the zero-point offset angle value in Example 3. There is no limitation here.

[0087] If the zero-point offset stored by the angle sensor includes the zero-point offset angle value, then the zero-point offset angle value can be directly substituted into the calculation. If the zero-point offset stored by the angle sensor is the zero-point offset voltage value, then it needs to be converted into the zero-point offset angle value before being substituted into the calculation.

[0088] Experiment 1

[0089] The experimental calibration results of applying this technical solution to batch products are shown in the table below:

[0090] Standard angle Before calibration After calibration -75 -74.69 -75.03 -70 -69.77 -70.01 -65 -64.82 -65.01 -60 -59.86 -60.02 -55 -54.88 -55.01 -50 -49.91 -50.02 -45 -44.92 -45.02 -40 -39.95 -40.02 -35 -34.95 -35.02 -30 -29.95 -30.02 -25 -24.97 -25.02 -20 -19.98 -20 -15 -14.99 -15 -10 -10 -10.01 -5 -5 -5 0 -0.01 0 5 4.98 4.99 10 9.97 9.99 15 14.95 14.99 20 19.94 19.99 25 24.94 25 30 29.93 30.01 35 34.91 35.01 40 39.89 39.99 45 44.88 44.99 50 49.86 50.01 55 54.82 54.99 60 59.8 60 65 64.75 65.01 70 69.68 70.02 75 74.55 75.02

[0091] As can be seen from the table above, this technical solution achieves the expected results for an accuracy of 0.1°.

[0092] The above description is merely a preferred embodiment of the present invention and does not limit the implementation and protection scope of the present invention. Those skilled in the art should realize that any equivalent substitutions and obvious changes made using the content of this specification and illustrations should be included within the protection scope of the present invention.

Claims

1. A calibration method for an angle sensor, characterized in that, A pre-configured turntable rotates along a vertical plane, and the calibration method includes: Step S1: Fix the angle sensor to be calibrated on the turntable, and then control the angle sensor to perform shaft zero-point calibration to obtain the zero-point offset and save it. Step S2: Control the turntable to rotate sequentially from a preset horizontal zero point position to at least one preset test angle, and when the turntable rotates to each test angle, control the angle sensor to perform sensitivity calibration based on the zero point offset to obtain the calibrated sensitivity corresponding to the test angle; The shaft zero-point calibration includes the following steps: Step S11: Adjust the turntable to the horizontal zero point position; Step S12: Fix the angle sensor to be calibrated on the turntable in the horizontal direction, and control the angle sensor to read the first voltage value output by its own accelerometer. Step S13: Control the turntable to rotate 180 degrees from the horizontal zero point position, and then control the angle sensor to read the second voltage value output by its own accelerometer; Step S14: The angle sensor processes the first voltage value and the second voltage value to obtain the zero-point offset. In step S14, the angle sensor calculates the average of the first voltage value and the second voltage value to obtain the zero-point offset voltage value; When the angle sensor is in the accelerometer's data writing state, it writes the zero-point offset voltage value as the zero-point offset into the accelerometer's register for storage, thereby setting the accelerometer to zero. In step S2, when the turntable rotates to each test angle, the angle sensor is controlled to read the real-time voltage value output by its own accelerometer, and the calibrated sensitivity corresponding to the test angle is calculated based on the real-time voltage value and the zero-point offset voltage value. The calculation formula is as follows: ； in, The calibrated sensitivity is used to represent the nth test angle. This is used to represent the real-time voltage value read at the nth test angle. Used to represent the nth test angle. The output value used to represent the zero-point offset voltage value is 0 after the accelerometer is set to zero. Used to represent the theoretical axis zero-point sensitivity of the angle sensor; When the accelerometer of the angle sensor does not allow data to be written, the zero-point offset includes a zero-point offset voltage value, which is stored in the microcontroller unit of the angle sensor; the microcontroller unit also stores the theoretical axis zero-point sensitivity of the angle sensor. In step S2, when the turntable rotates to each test angle, the angle sensor is controlled to read the real-time voltage value output by its own accelerometer, and the calibrated sensitivity corresponding to the test angle is calculated based on the real-time voltage value, the zero-point offset voltage value, and the theoretical axis zero-point sensitivity. The calculation formula is as follows: ； in, The calibrated sensitivity is used to represent the nth test angle. This is used to represent the real-time voltage value read at the nth test angle. Used to represent the nth test angle. The output value used to represent the zero-point offset voltage value This is used to represent the theoretical axis zero-point sensitivity of the angle sensor.

2. The calibration method according to claim 1, characterized in that, When the accelerometer of the angle sensor does not allow data to be written; In step S14, the zero-point offset angle value is obtained by processing the zero-point offset voltage value and the pre-acquired theoretical axis zero-point sensitivity. The zero-point offset angle value is used as the zero-point offset amount and saved to the microcontroller unit of the angle sensor.

3. The calibration method according to claim 2, characterized in that, The formula for calculating the zero-point offset angle value is as follows: ； in, Used to represent the zero-point offset angle value. The output value used to represent the zero-point offset voltage value Used to represent the zero-point sensitivity of the theoretical axis.

4. The calibration method according to claim 3, characterized in that, In step S2, when the turntable rotates to each test angle, the angle sensor is controlled to read the real-time voltage value output by its own accelerometer, and the calibrated sensitivity corresponding to the test angle is calculated based on the real-time voltage value and the zero-point offset angle value. Then: ； in, The calibrated sensitivity is used to represent the nth test angle. This is used to represent the real-time voltage value read at the nth test angle. Used to represent the nth test angle. Used to represent the zero-point offset angle value.

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