KR102032463B1 - Apparatus for measuring steering angle of vehicle - Google Patents

Abstract

Disclosed is a steering angle measuring device arranged on-axis with a shaft axis to measure a steering angle of a vehicle. The disclosed steering angle measuring device includes a magnet located at one end of a shaft; A plurality of Hall sensors spaced apart from the magnet by a predetermined distance; And a data processor configured to calculate a steering angle using the sensing value of the hall sensor.

Description

Steering angle measuring device of vehicle {APPARATUS FOR MEASURING STEERING ANGLE OF VEHICLE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering angle measuring device, and more particularly, to an apparatus for measuring a steering angle of a vehicle by being coaxial with the shaft axis.

The steering angle measuring apparatus of a vehicle measures a steering angle of a steering wheel in real time and measures the steering angle by detecting a rotation of a shaft, which is generally a rotation axis of the steering wheel.

As an example, the steering angle is measured by using a magnet coupled to the shaft in a ring shape and a magnetic sensor spaced apart from the magnet. Such a method is called an off-axis array method. Alternatively, the steering angle may be measured in an optical manner using an optical sensor such as an encoder.

The optical method requires a closed room and there is a high probability of error due to the characteristics of the vehicle that are easily exposed to external light. As such, compensation logic is essential. In addition, encoders cannot obtain information about the direction of rotation, so additional sensors are needed.

The non-coaxial arrangement in which the magnetic sensor is spaced apart from the rotating shaft does not interfere with the movement of the rotating shaft and can obtain a large magnetic change. However, there is a limitation in miniaturization due to the separation distance.

Accordingly, in recent years, studies have been conducted to measure steering angle by arranging components for steering angle measurement coaxially with a central axis of a shaft, which is a rotational axis, and as related related arts, Korean Patent Laid-Open Publication No. 2012-0070161 There is an arc.

Further, in order to solve the problem that the measurement value of the magnetic sensor using the magnetic field may be inaccurate by an external magnetic field, studies are being conducted to correct the measurement value of the sensor based on magnetic disturbance caused by the external magnetic field. As a related prior document, a parallel Kalman filter for magnetic disturbance and posture estimation using a non-patent document “9-axis inertial / magnetic sensor, Lee, Jung-Keun, Trans. Korean Soc. Mech. Eng. A, Vol. 40, no. 7, pp. 659-666, 2016.

The present invention is to provide a steering angle measuring device that can be arranged coaxially with the shaft axis to measure the steering angle.

In another aspect, the present invention is to provide a steering angle measuring device that can measure the steering angle by correcting the external magnetic disturbance.

According to an embodiment of the present invention for achieving the above object, a magnet located at one end of the shaft; A plurality of Hall sensors spaced apart from the magnet by a predetermined distance; And a data processing unit configured to calculate a steering angle using the sensing value of the hall sensor.

In addition, according to another embodiment of the present invention for achieving the above object, a housing coupled to one end of the shaft and including an inertial sensor; A magnet coupled to one surface of the housing; A plurality of Hall sensors spaced apart from the magnet by a predetermined distance; And a data processor configured to calculate a steering angle by using the sensing values of the hall sensor and the inertial sensor.

In addition, according to another embodiment of the present invention for achieving the above object, an inertial sensor coupled to one end of the shaft; A magnet located between the inertial sensor and one end of the shaft; A plurality of Hall sensors spaced apart from the magnet by a predetermined distance; And a data processor configured to calculate a steering angle by using the sensing values of the hall sensor and the inertial sensor.

According to the present invention, it is possible to provide a miniaturized steering angle measuring device by disposing a magnet and a hall sensor in a coaxial arrangement method, and to remove the noise of the hall sensor itself using a plurality of Hall sensors to improve the accuracy of the measured steering angle. Can be improved.

In addition, according to the present invention, when measuring the steering angle using the Hall sensor, by reflecting the magnetic disturbance caused by the external magnetic field, the accuracy of the steering angle measurement can be improved.

1 is a view for explaining a steering angle measuring device according to an embodiment of the present invention.
2 is a diagram illustrating a sensing value of a hall sensor and a differential signal generated from the sensing value.
3 is a view for explaining a steering angle measuring device according to another embodiment of the present invention.
4 is a view for explaining the maximum error of the steering angle measurement apparatus according to an embodiment of the present invention.
5 is a diagram for describing stabilization of a steering angle measurement value according to a magnetic disturbance correction.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. In describing the drawings, similar reference numerals are used for similar elements.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view for explaining a steering angle measuring device according to an embodiment of the present invention, Figure 2 is a view for explaining a differential value generated from the sensing value and the sensing value of the Hall sensor.

Referring to FIG. 1, the steering angle measuring apparatus according to the present invention includes a magnet 110, a plurality of hall sensors 121 to 124, and a data processor 130. Alternatively, another type of magnetic sensor may be used instead of the hall sensor, and an AMR sensor, a GMR sensor, or the like may be used.

The magnet 110 is located at one end of the shaft 140, which is a rotation axis of the steering wheel, and is coupled to one end of the shaft 140. The magnet 110 may be included in the housing and coupled to the shaft 140 or exposed to the outside and coupled to the shaft 140. In addition, the magnet 110 may be, for example, a flat circular shape. In FIG. 1, a magnet 110 having a diameter larger than the diameter of the shaft 140 is illustrated, but the diameter of the magnet may vary depending on the embodiment. .

The hall sensors 121 to 124 are spaced apart from the magnet 110 by a predetermined distance. The number of Hall sensors may be variously determined according to an embodiment. In FIG. 1, an embodiment in which four Hall sensors 121 to 124 are used will be described. In particular, the steering angle measuring device according to the present invention, by using a plurality of hall sensors instead of a single hall sensor, can be removed later, but the noise of the hall sensor itself.

The Hall sensors 121 to 124 may be disposed on the substrate 150, and may be disposed in each of the four quadrants such that some or all of the Hall sensors are included in the diameter of the magnet 110.

In this case, the hall sensors 121 to 124 may be disposed in the quadrant so as to be symmetrical apart from the center axis 160 of the shaft 140 and the center 151 of the quadrant through which the center axis 160 passes. In addition, the magnet 110 may also be disposed such that the central axis of the magnet corresponds to the central axis 160 of the shaft 140. In other words, in the steering angle measuring device according to the present invention, the magnet 110 and the plurality of Hall sensors 121 to 124 are disposed coaxially with the central axis 160 of the shaft 140 that is the rotation axis.

The data processor calculates a steering angle by using the sensing values of the hall sensors 121 to 124 and may be disposed on the substrate 150 although not shown in the drawing.

More specifically, the data processor may calculate the steering angle by using a differential signal of the hall sensor sensing value in order to remove common noise of the hall sensor itself. In one embodiment, the data processing unit, as shown in [Equation 1], in the sum of the sensing values (V _HS1 , V _HS2 ) of the Hall sensors 121, 122 disposed in the first and second quadrants, The first signal Signal 1, which is a signal obtained by subtracting the sensing values V _HS3 and V _HS4 of the hall sensors 123 and 124 disposed in the four quadrants, and the hall sensors 121 and 124 disposed in the first and fourth quadrants. The second signal (S) which is a signal obtained by subtracting the sensing values V _HS2 and V _HS3 of the Hall sensors 122 and 123 disposed in the second and third quadrants from the sum of the sensing values V _HS1 and V _HS4 . The steering angle can be calculated using Signal 2). Depending on the number or arrangement of Hall sensors, the differential signal can be calculated in various ways.

Referring to FIG. 2, the sensing value (y-axis) of the hall sensor is output as a sinusoidal waveform according to the rotation angle of the magnet, that is, the steering angle (x-axis), and the first and second signals are sinusoids representing a phase difference of 90 degrees. Indicates the waveform. As a result, the first and second signals correspond to the output values of the sine function and the cosine function, and thus the data processor may calculate the steering angle θ by using the arc tangent function as shown in [Equation 2].

For example, when the first signal value at a specific time point calculated by the rotation of the steering wheel is -2 and the second signal value is 2, the data processor may calculate that the steering angle at this specific time point is 135 degrees.

In order to use Equation 2, a sum and subtraction of sensing values of Hall sensors having a phase difference of 90 degrees can be combined to generate a differential signal representing a phase difference of 90 degrees while noise is removed. .

As a result, according to the present invention, it is possible to provide a miniaturized steering angle measuring device by disposing a magnet and a hall sensor in a coaxial arrangement, and to remove the noise of the hall sensor itself by using a plurality of Hall sensors. Can improve the accuracy.

On the other hand, as described above, the Hall sensors 121 to 124 and the magnets 110 are spaced apart from each other, the accuracy of the sensing value may decrease depending on the distance between the magnet 110 and the Hall sensors 121 to 124. have.

For example, when the magnetic strength of the magnet is large, even if the distance between the magnet 110 and the Hall sensors 121 to 124 is increased, the Hall sensor can easily detect the change in the magnetic field. Alternatively, even though the measurement range of the Hall sensor is not wide, the sensing value of the Hall sensor may be saturated when the magnetic force of the magnet is too strong. Alternatively, even if the sensitivity of the Hall sensor is not good, when the distance between the magnet 110 and the Hall sensors 121 to 124 is too long or the magnetic strength of the magnet is small, the sensing value of the Hall sensor may become inaccurate due to noise. Can be.

Therefore, the distance between the magnet 110 and the Hall sensors 121 to 124 may be determined according to at least one of the magnetic strength of the magnet 110, the sensitivity of the Hall sensor, and the measurement range.

3 is a view for explaining a steering angle measuring device according to another embodiment of the present invention.

The steering angle measuring device illustrated in FIG. 3 further includes a housing 370 as compared to the steering angle measuring device described in FIG. 2, and may further include a shield 380 according to an exemplary embodiment.

The housing 370 is coupled to one end of the shaft 140 and includes an inertial sensor. The housing 370 may include an acceleration sensor, a gyro sensor, and a magnetic sensor as an inertial sensor. The data processor may calculate the magnetic disturbance value of the magnet 110 and the external magnetic field from the sensing value of the inertial sensor and reflect the calculated magnetic disturbance value in the steering angle calculation.

Since the steering angle measuring apparatus according to the present invention is based on a hall sensor, an error may occur in the steering angle due to magnetic disturbance, and thus an inertial sensor is used to reflect the magnetic disturbance in the steering angle.

The data processor calculates the steering angle by using the sensing values of the Hall sensor and the inertial sensor. As described above, the data processing unit calculates the steering angle by generating the first and second signals from the sensing values of the hall sensor, and reflects the magnetic disturbance value caused by the surrounding magnetic field to the sensing value of the hall sensor, thereby the first and second signals. Create And the magnetic disturbance value may be generated from the sensing value of the inertial sensor.

The data processor may calculate a magnetic disturbance value using a Kalman filter, and as an example, calculates an attitude matrix of an X-axis (roll) of the attitude matrix of the inertial sensor using the sensing values of the gyro sensor and the acceleration sensor. The attitude matrix and the magnetic disturbance value of the Z-axis are calculated among the attitude matrices for the inertial sensor using the gyro sensor and the sensing values of the magnetic sensor. As will be described below, the attitude matrix can be used to change the coordinate system for the self disturbance value.

The present invention is characterized by reflecting the magnetic disturbance value to the measured steering angle, and is not characteristic of the method of calculating the magnetic disturbance value, and the method of calculating the magnetic disturbance value is disclosed in the above-described prior art and the like. Therefore, the description of the detailed method of calculating the magnetic disturbance value will be omitted.

The calculated magnetic disturbance value may represent a positive or negative number. When the magnetic disturbance value is a positive value, the data processing unit generates the first and second signals by using the sensing values of the Hall sensor to which the magnetic disturbance value is added. When the magnetic disturbance value is negative, the first and second signals may be generated using the sensing value of the hall sensor from which the magnetic disturbance value is subtracted.

At this time, the sensing value of the Hall sensor is a voltage value, and the magnetic disturbance value represents the magnetic flux density (Tesla, T). Therefore, the magnetic disturbance value is multiplied by the voltage value by multiplying the sensitivity value (mT / volt) for each Hall sensor. This can be reflected in the sensing value of.

In addition, since the above-described magnetic disturbance value is a value observed in the sensor coordinate system, it is necessary to correct the magnetic disturbance value with respect to the absolute coordinate system, and the magnetic disturbance value with respect to the absolute coordinate system may be calculated through the aforementioned attitude vector. An attitude matrix on the X axis and an attitude matrix on the Y axis may be calculated from the attitude matrix on the Z axis, and a magnetic disturbance value on the absolute coordinate system may be calculated from the final attitude vector.

The shield 390 is positioned between the magnet and the inertial sensor and is made of a material capable of blocking magnetic force to reduce the influence of the magnet on the inertial sensor.

On the other hand, the magnet 110 is coupled to one surface of the housing 370. According to an embodiment, the inertial sensor may be coupled to one end of the shaft 140 without a housing, and may be coupled to the shaft in a form of being inserted into a groove formed at one end of the shaft 140. At this time, the magnet 110 may be located at one end of the shaft, the inertial sensor may be located between the magnet and the shaft.

4 is a view for explaining the maximum error of the steering angle measurement apparatus according to an embodiment of the present invention, Figure 5 is a view for explaining the stabilization of the steering angle measurement value according to the magnetic disturbance correction.

Referring to FIG. 4, it can be seen that the maximum difference between the actual steering angle True and the steering angle calculated by the present invention is about 0.5 degrees. Comparing the maximum error of the current commercial steering angle measuring device is 1.8 degrees to 2.5 degrees, it can be seen that the accuracy of the steering angle measuring device according to the present invention is very high.

In addition, referring to FIG. 5, it is understood that the steering angle measurement value when the magnetic disturbance is compensated (with compensation) converges quickly to the actual steering angle while having a small difference from the actual steering angle (truth) compared with the case where the compensation is not performed (without compensation). Can be. According to the present invention, it can be seen that the correction of the magnetic disturbance not only improves the accuracy of the steering angle measurement but also stabilizes much faster.

In the present invention as described above has been described by the specific embodiments, such as specific components and limited embodiments and drawings, but this is provided to help a more general understanding of the present invention, the present invention is not limited to the above embodiments. For those skilled in the art, various modifications and variations are possible from these descriptions. Therefore, the spirit of the present invention should not be limited to the described embodiments, and all of the equivalents or equivalents of the claims as well as the claims to be described later belong to the scope of the present invention. .

Claims (13)

delete delete delete delete delete delete A housing including an inertial sensor for measuring a magnetic disturbance due to a peripheral magnetic field, the housing coupled to one end of a shaft which is a rotation axis of the steering wheel;
A magnet coupled to one surface of the housing;
A shield included in the housing and positioned between the magnet and the inertial sensor;
A plurality of Hall sensors spaced apart from the magnet by a predetermined distance; And
It includes a data processing unit for calculating the steering angle (θ) by using the sensing value of the Hall sensor and the inertial sensor,
The data processing unit calculates the steering angle by applying first and second signals generated from the sensing values of the hall sensor to the following equation to remove common noise of the hall sensor,
The first signal Signal 1 is a signal obtained by subtracting the sensing values of the Hall sensors disposed in the third and fourth quadrants from the sum of the sensing values of the Hall sensors disposed in the first and second quadrants,
The second signal Signal 2 is a signal obtained by subtracting the sensing values of the hall sensors disposed in the second and third quadrants from the sum of the sensing values of the hall sensors disposed in the first and fourth quadrants.
Steering angle measuring device of the vehicle.
[Equation]

The method of claim 7, wherein
The Hall sensor is
Some or all of each of the Hall sensors is disposed in each of the four quadrants so as to fall within the diameter of the magnet.
Steering angle measuring device of the vehicle.
delete The method of claim 7, wherein
The inertial sensor
Including acceleration sensor, gyro sensor and magnetic sensor,
The data processing unit
The first and second signals are generated by reflecting a magnetic disturbance by a peripheral magnetic field, which is generated from a sensing value of the inertial sensor, into a sensing value of the hall sensor.
Steering angle measuring device of the vehicle.
The method of claim 10,
The data processing unit
When the magnetic disturbance value is positive, the first and second signals are generated by using the sensing values of the Hall sensor, the magnetic disturbance value being summed,
When the magnetic disturbance value is negative, the first and second signals are generated by using the sensing value of the hall sensor from which the magnetic disturbance value is subtracted.
Steering angle measuring device of the vehicle. delete delete

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