JP2003050125A - Rotation angle detector, torque detector and steering mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotation angle detector which eliminates the need to change over channels of its detecting means. SOLUTION: This rotation angle detector, which has a target or a plurality of targets 20 formed on a rotor to cause an adjacent first detection means 1A to output a detection signal, according as the rotor 2 fitted to a shaft 31 rotates, has a second detecting means 1B which outputs a detection signal differing by a specified angle from that of the first means 1A, and detects the rotation angle of the shaft 31, on the basis of the detection signals outputted respectively by both detecting means 1A, 1B. The detector is provided with approximation means 4a, 4b for making one of the detection signals outputted by the first and second detecting means 1A, 1B approximated into a sine function and the other into a cosine function respectively, a means 4 for obtaining a tangent function, on the basis of those approximated sine and cosine functions, and a means 4c for obtaining the inverse function of that found tangent function, and the inverse function found is set as the detected rotation angle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation angle detecting device for detecting a rotation angle of a rotary shaft, a torque detecting device equipped with this rotation angle detecting device for detecting a rotary torque applied to a rotary shaft, and a torque detecting device for the same. The present invention relates to a steering device for a vehicle provided with the vehicle.

[0002]

2. Description of the Related Art A steering assisting motor is driven on the basis of a detection result of steering torque applied to a steering wheel for steering, and a rotational force of the motor is transmitted to a steering device to assist steering. Compared with a hydraulic power steering device that uses a hydraulic actuator as a source of a steering assist force, the electric power steering device can easily control the assist force characteristics according to the traveling state such as the vehicle speed level and the steering frequency. Since it has such an advantage, its application range tends to expand in recent years.

In the electric power steering apparatus as described above, a torque detecting apparatus for detecting the steering torque is required, and the steering shaft connecting the steering wheel and the steering mechanism is
The input shaft on the steering wheel side and the output shaft on the steering mechanism side are configured to be connected via a small-diameter torsion bar, and the torsion bar is twisted by the action of the steering torque to occur in the connection part of the two shafts. There is used a torque detection device configured to detect a relative angular displacement and calculate a steering torque (rotational torque) based on the detection result.

Most of the torque detecting devices described above are
The rotation angle of each of the input shaft and the output shaft is detected, and the rotational torque is obtained by using the relative angular displacement given as the difference between the detected angles. However, many of the rotation angle detection devices are configured to include a contact sliding portion such as a potentiometer, which causes deterioration of output due to wear of the sliding contact portion, which causes a problem of poor durability. there were. Further, a device configured to detect the relative angular displacement between the input shaft and the output shaft caused by the torsion of the torsion bar through the impedance change of the magnetic circuit formed in the connecting portion of both shafts has been put into practical use. However, this device has a problem that the structure is complicated and the manufacturing cost is high.

In order to solve such a problem, the applicant of the present application has proposed in Japanese Patent Application No. 2000-294731 or the like a torque detecting device having a simple structure capable of detecting the rotating torque applied to the rotating shaft in a non-contact manner. . In this torque detection device, one or a plurality of magnetic targets are used to output a detection signal from a magnetic sensor (MR sensor) in proximity to a rotating body provided on a target rotating shaft. And a rotation angle detection device for detecting the rotation angle of the rotation shaft from the magnetic sensor based on the detection signal output from the magnetic sensor, is provided at each of the connecting portions of the input shaft and the output shaft.

According to this structure, the magnetic sensor emits a voltage output that changes in a cycle corresponding to the number of targets arranged in parallel per one rotation of the rotary shaft, so that the rotation angles of the input shaft and the output shaft correspond to each other. Can be detected in a non-contact manner based on the output of the magnetic sensor, and the rotational torque (steering torque) applied to the input shaft by operating the steering wheel is given as the output difference of the magnetic sensors corresponding to the input shaft and the output shaft. It can be calculated based on the difference between the rotation angles of the two axes.

In the targets arranged side by side on the outer periphery of the rotating body as described above, the output of the magnetic sensor changes non-linearly near the maximum value and the minimum value, and within the non-linearly changing region. There is a problem that the detection of the rotation angle becomes uncertain. Therefore, two magnetic sensors are arranged outside the side-by-side position of the targets with a phase shift in the circumferential direction, and when the output of one is in the non-linear change region, the output of the other magnetic sensor is used to rotate over the entire circumference. The corners can be detected.

As described above, the torque detection device proposed in Japanese Patent Application No. 2000-294731 has a simple structure capable of detecting the rotational torque of the target rotating shaft in a non-contact manner.
As described above, the electric power steering device can be conveniently used for drive control of a motor for assisting steering.

[0009]

However, the output characteristics of the magnetic sensor are not constant and are easily affected by the ambient temperature. As described above, two magnetic sensors are provided outside the target of the input shaft and the output shaft. In the configuration including
There is a problem that the difference in the output characteristics of the magnetic sensors causes a decrease in the calculation accuracy of the rotational torque calculated based on these output differences.

Therefore, the applicant of the present application filed Japanese Patent Application No. 2000-3.
At 26088, an average value of the portions detected by the two magnetic sensors is calculated, and a torque detection device that corrects the results detected by the respective magnetic sensors so that the portions detected by the two magnetic sensors match the average value. Is proposed. However, in this correction method,
Even if correction is performed between two magnetic sensors, the correction is performed independently of the other two magnetic sensors that are arranged out of phase with each other. The mechanical distortion and the like are not corrected, and a difference occurs in the output gain. Therefore, for torque calculation, two magnetic sensor channels on one side and two channels on the other side are used.
When switching between the channels of two magnetic sensors, there is a problem that a step (difference) occurs in the detected calculation torque.

The present invention has been made in view of the above-mentioned circumstances, and it is an object of the first and second inventions to provide a rotation angle detecting device which does not require switching of channels of detecting means. It is an object of the third invention to provide a torque detecting device which does not require switching of the channel of the detecting means. A fourth aspect of the present invention aims to provide a steering device including the torque detection device according to the third aspect.

[0012]

According to a first aspect of the present invention, there is provided a rotation angle detecting device in which a first detecting means which is adjacent to the rotary shaft outputs a detection signal as a rotating body provided on a rotary shaft rotates.
One or more targets are provided on the rotating body,
The detection means outputs a detection signal that differs from the first detection means by a predetermined angle, and based on the detection signals output by the first detection means and the second detection means, respectively, the first of the rotating shafts is detected.
A rotation angle detection device for detecting a rotation angle from a detection means or a second detection means, wherein one of the detection signals output by the first detection means and the second detection means is a sine function and the other is a cosine function. An inverse means obtained by the approximating means for approximating, a means for obtaining a tangent function based on the sine function and a cosine function approximated by the approximating means, and means for obtaining an inverse function of the tangent function obtained by the means. It is characterized in that the function is set to the rotation angle.

In this rotation angle detecting device, one or a plurality of targets are provided on the rotating body so that the first detecting means adjacent to the rotating body outputs a detection signal as the rotating body provided on the rotating shaft rotates. . The second detection means outputs a detection signal different from the first detection means by a predetermined angle, and based on the detection signals respectively output by the first detection means and the second detection means,
The rotation angle of the rotating shaft from the first detecting means or the second detecting means is detected. The approximating means approximates one of the detection signals output by the first detecting means and the second detecting means to a sine function and the other to a cosine function, and obtains a tangent function by means of a sine function approximated by the approximating means. Find the tangent function based on the cosine function. The means for obtaining the inverse function obtains the inverse function of the tangent function obtained by the means for obtaining the tangent function, and uses the inverse function obtained by the means for obtaining the inverse function as the rotation angle. This allows
It is possible to realize a rotation angle detection device that does not need to switch the channel of the detection means.

In the rotation angle detecting device according to the second aspect of the present invention, the approximating means respectively outputs one or the other of the detection signals previously output by the first detecting means and the second detecting means, the sine function and the cosine function. Two corresponding tables are provided, and the tables are referred to based on the respective detection signals output by the first detection means and the second detection means.

In this rotation angle detecting device, the approximating means is
The first detection means and the second detection means are provided with two tables in which one and the other of the detection signals previously output and the sine function and the cosine function are associated with each other.
Since the table is referred to on the basis of the respective detection signals output by the detection means, the respective results output by the first detection means and the second detection means can be accurately approximated to the sine function and the cosine function, respectively. It is possible to realize a rotation angle detection device that does not require switching of the channels.

A torque detecting device according to a third aspect of the present invention is a torque detecting device for detecting a torque applied to a first shaft based on a twist angle generated in a connecting shaft that coaxially connects the first shaft and the second shaft, The rotation angle detecting device according to claim 1 or 2 is attached to each of the first shaft and the second shaft, and the difference between the rotation angles detected by the rotation angle detecting device is set as the twist angle. It is characterized by being.

In this torque detecting device, the torque applied to the first shaft is detected based on the twist angle generated in the connecting shaft that coaxially connects the first shaft and the second shaft. The rotation angle detecting device according to claim 1 or 2 is attached to each of the first shaft and the second shaft, and the difference between the rotation angles detected by each of the rotation angle detecting devices is used as a twist angle. It is possible to realize a torque detection device that does not need to be switched.

A steering device according to a fourth aspect of the present invention comprises a first shaft connected to a steering wheel, a second shaft connected to a steering mechanism, and a connecting shaft connecting the first shaft and the second shaft. The torque detecting device according to claim 3, wherein the steering torque applied to the first shaft is detected based on a twist angle generated in the connecting shaft, and steering assist is performed according to the steering torque detected by the torque detecting device. It is characterized by being present.

In this steering apparatus, the first shaft is connected to the steering wheel, the second shaft is connected to the steering mechanism, the connecting shaft connects the first shaft and the second shaft, and the torque according to claim 3 The detector is
The steering torque applied to the first shaft is detected based on the twist angle generated in the connecting shaft, and the steering assist is performed according to the steering torque detected by the torque detection device. Therefore, the steering device including the torque detection device according to the third aspect of the present invention. Can be realized.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing the embodiments thereof. FIG. 1 is a schematic diagram showing a configuration example of an embodiment of a rotation angle detection device and a torque detection device according to the present invention applied to a steering device for an automobile. This steering device has an input shaft 31 (first shaft) whose upper end is connected to a steering wheel 30 (steering wheel) and an output shaft 32 (second shaft) whose lower end is connected to a pinion 33 of a steering mechanism.
According to the present invention, a steering shaft 3 (rotating shaft) that connects the steering wheel 30 and the steering mechanism is coaxially connected to each other via a small-diameter torsion bar 34 (coupling shaft). The rotation angle detection device and the torque detection device are configured as follows near the connecting portion of the input shaft 31 and the output shaft 32.

A disk-shaped target plate 2 (rotating body) is coaxially fitted and fixed to the input shaft 31 in the vicinity of the end portion on the side connected to the output shaft 32. On the surface, a plurality of V-shaped or inverted V-shaped (in the figure, 5
.) Targets 20, 20, ... Are connected and arranged in parallel. FIG. 2 is a development view in which the outer peripheral surface of the target plate 2 is developed. As shown in FIG. 2, the target 20 includes a first inclined portion 21 that is inclined in one direction along the outer peripheral surface of the target plate 2 and a second inclined portion 21 that is inclined in the other direction.
The protrusions are made of a magnetic material and are provided in parallel with each other in the circumferential direction of the outer peripheral surface of the target plate 2. First
The inclined portion 21 and the second inclined portion 22 are line-symmetric with respect to a straight line that passes through the connection points and that is the axial direction of the steering shaft 3.

A target plate 2 having similar targets 20, 20, ... Is externally fitted and fixed near the end of the output shaft 32 connected to the input shaft 31, and the target plate on the output shaft 32 side is fixed. 2 has targets 20, 20, ...
, And the targets 20, 20, ... Of the target plate 2 on the input shaft 31 side are aligned in the circumferential direction.

A sensor box 1 is arranged outside each of the target plates 2 and 2 so as to face the outer edges of the respective targets 20, 20 ,. The sensor box 1 is fixedly supported on a stationary part such as a housing that supports the input shaft 31 and the output shaft 32. Inside the sensor box 1, there are magnetic sensors 1A, 1B, 2A, 2B.
(First detecting means or second detecting means) is stored,
The magnetic sensors 1A and 1B are the targets 2 on the input shaft 31 side.
0, 20, ... Are arranged so as to face a portion where the electrical angle differs by 90 ° in the circumferential direction. The magnetic sensors 2A, 2B have an electrical angle of 9 in the circumferential direction of the targets 20, 20, ... On the output shaft 32 side.
It is arranged so as to face a site that differs by 0 °. The magnetic sensors 1A and 2A and the magnetic sensors 1B and 2B are in a state where their circumferential positions are correctly aligned.

The magnetic sensors 1A, 1B, 2A, and 2B use elements having a characteristic such that their electric characteristics (resistance) are changed by the action of a magnetic field, such as a magnetoresistive effect element (MR element). Is a sensor configured to change the output voltage according to the output voltage V1A, V1B, V2A, V2B.
Are provided to the arithmetic processing unit 4 including a microprocessor provided outside (or inside) the sensor box 1.

The targets 20, 20, ... Where the magnetic sensors 1A, 1B, 2A, 2B face each other are, as described above, the respective target plates 2, 2 coaxially fitted and fixed to the input shaft 31 and the output shaft 32. , Which are inclined in one direction along the outer peripheral surface, and second inclined portions 22, 22, which are inclined in the other direction, are arranged in parallel in the circumferential direction. It is a ridge made of magnetic material. Therefore, when the input shaft 31 and the output shaft 32 rotate around the axes, the magnetic sensors 1A, 1
B, 2A, 2B are corresponding targets 20, 20 ,.
Output a voltage signal that proportionally rises or falls in response to changes in the rotation angles of the input shaft 31 and the output shaft 32 while passing through the positions facing each other.

Therefore, the respective rotation angles of the input shaft 31 and the output shaft 32 can be detected in a non-contact manner based on the respective outputs of the magnetic sensors 1A, 1B and 2A, 2B corresponding to the respective rotation angles of the steering wheel 30. The rotational torque (steering torque) applied to the input shaft 31 by the operation is the same as the input shaft 31 and the output shaft 3.
It can be calculated based on the difference between the rotation angles of both shafts given as the output difference of the magnetic sensors 1A, 1B and 2A, 2B corresponding to 2.

The outputs of the magnetic sensors 1A, 1B, 2A and 2B change non-linearly in the vicinity of the apex and the connection point of the V-shape or the inverted V-shape, and have a sin wave shape. Therefore, depending on the size of the targets 20, 20, ..., The outputs of the magnetic sensors 1A, 1B, 2A, 2B can be close to sin waves (sine waves). Further, since the magnetic sensors 1A, 1B are arranged so as to face the parts having different electrical angles of 90 ° in the circumferential direction of the targets 20, 20 ,.
From sin (θ ± (π / 2)) = ± cos θ, when rotating from the magnetic sensor 1B to the magnetic sensor 1A direction, as shown in FIG. 4, the outputs V1A and V1B of the magnetic sensors 1A and 1B are obtained.
Can be regarded as V1A = sin θ and V1B = cos θ. Similarly for the magnetic sensors 2A and 2B, the outputs V2A and V2B can be regarded as V2A = sin θ and V2B = cos θ.

Therefore, a reference table in which the outputs of the magnetic sensors 1A and 2A from which the midpoint voltage value has been subtracted and the sin waves are associated with each other after the correction to be described later is prepared in advance, and is used as a sin approximation table 4a (approximation means). It is built in the arithmetic processing unit 4 so that the corrected outputs of the magnetic sensors 1A and 2A are approximated to sin values. Similarly, in advance,
Magnetic sensor 1 with the midpoint voltage value subtracted after the correction described below
A reference table in which the outputs of B and 2B and the cos waves are associated with each other is created, and the cos approximation table 4b (approximation means) is created.
Is incorporated in the arithmetic processing unit 4 so that the corrected outputs of the magnetic sensors 1B and 2B are approximated to the cos value. At the time of creating each reference table, the corrected midpoint voltage value of each output of the magnetic sensors 1A, 2A, 1B, 2B is obtained and stored.

Further, based on the sin value and the cos value obtained by approximation from tan θ = sin θ / cos θ,
Tan θ can be obtained, and the rotation angle θ at that time can be obtained from its inverse function. Therefore, tan which is a reference table of the tan value and the corresponding angle θ
The search table 4c (means for obtaining) is built in the arithmetic processing unit 4.

The operation of the rotation angle detecting device, the torque detecting device and the steering device according to the present invention having such a configuration will be described below with reference to the flowchart of FIG. 3 showing the operation. First, the arithmetic processing unit 4 includes the magnetic sensors 1A and 1A.
B, 2A, 2B sensor outputs V1A, V1B, V2A, V2B
Is read (S2), and each is A / D (analog / digital) converted (S4). Next, the arithmetic processing unit 4
Each A / D-converted sensor output is corrected by the method described below (S6), and each midpoint voltage value is subtracted from each corrected sensor output to prepare for approximation to a sin wave or cos wave. (S8).

Next, the arithmetic processing unit 4 calculates the sin approximation table 4 based on the sensor output V1A obtained by subtracting the midpoint voltage value.
a), sin sin1 is obtained, and based on the sensor output V1B obtained by subtracting the midpoint voltage value, cosθ1 is obtained by referring to the cos approximation table 4b, and the sin approximation table is obtained based on the sensor output V2A obtained by subtracting the midpoint voltage value. 4a, sin θ2 is obtained, and based on the sensor output V2B obtained by subtracting the midpoint voltage value, cos θ2 is obtained by referring to the cos approximation table 4b, and sensor outputs V1A, V1B, V2A, V
2B is approximated to a sin value or a cos value, respectively (S1
0). At this time, the arithmetic processing unit 4 sets cos θ1 = 0, c
If osθ2 = 0, for example, cosθ1 = 0.00
001, cos θ2 = 0.00001 to prevent the denominator from becoming 0 at the next tan calculation (S
12).

Next, the arithmetic processing section 4 tan θ1 = si
n θ1 / cos θ1, tan θ2 = sin θ2 / cos
θ2 is calculated (S14). The value of tan θ theoretically takes a value of −∞ to + ∞, but actually takes a finite value depending on the processing capacity of the arithmetic processing unit 4. Next, the arithmetic processing unit 4 sets t
Inverse function of an θ1 and tan θ2 arctan θ1 = θ
1, arctan θ2 = θ2, and tan search table 4
Using c, the binary search method (S16, 20) is obtained (S18, 22). As shown in FIG. 5, the graph of tan θ is infinite and infinite small around the θ value corresponding to 90 °, but the tan search table 4c is shown in FIG. 6 to enable the binary search. Thus, the positions of infinity and infinity around the θ value corresponding to 90 ° are the maximum (θ value corresponding to + 90 °) and the minimum (θ corresponding to −90 °, respectively).
It is moved to the position of (value) and changed from -∞ to + ∞.

FIG. 7 is a flow chart showing the operation of calculating the angular difference between the input shaft 31 and the output shaft 32.
Each step of 41 to 245 corresponds to the tan search table 4c.
As described above, the tan data is created by shifting the 90 ° portion, and when the angle difference across 90 ° is obtained, it is necessary to return the angle to the original value. Angle θ
If the signs of 1 and θ2 do not match, it means that the angle crosses 90 °, so if you subtract 180 ° to the sign side of either of the angles θ1 and θ2 and subtract, the angle difference between the input and output axes Can be asked.

Next, the arithmetic processing section 4 obtains the calculated angles θ1,
The angle difference between the input shaft 31 and the output shaft 32 is calculated based on θ2 (S18, 22) (S24). The arithmetic processing unit 4
When calculating the angular difference between the input shaft 31 and the output shaft 32 (S
24) first determines whether or not the signs of the angles θ1 and θ2 match (S241 in FIG. 7). If the signs do not match, it is determined whether tan θ1 is greater than 0 (S242). ).

If tan θ1 is not larger than 0 (S242), the arithmetic processing section 4 adds 180 ° to the angle θ1 and changes it to a corrected value (S243). The arithmetic processing unit 4 is t
If an θ1 is greater than 0 (S242), 180 ° is added to the angle θ2 to change the corrected value (S245).
Next, the arithmetic processing unit 4 calculates the angle difference = θ1−θ2 (S244) and returns. The arithmetic processing unit 4 determines the angle θ.
When the signs of 1 and θ2 match (S241), the angle difference = θ1−θ2 is calculated as it is (S244) and the process returns.

Next, the arithmetic processing unit 4 converts the calculated angular difference (S244) into a steering torque value (S26 in FIG. 3) and outputs it (S28) and returns. From the above, the sensor outputs V1A and V2A of the magnetic sensors 1A and 2A are respectively si
The two sin waveforms when viewed as n values and the sensor outputs V1B and V2B of the magnetic sensors 1B and 2B are co
The two cos waveforms when considered as the s value are shown in FIG.
As shown in FIG. 8, if the torsion bar 34 has a small twist and there is almost no phase difference, as shown in FIG.
The calculated torque value becomes smaller.

On the other hand, two sin waveforms when the sensor outputs V1A and V2A of the magnetic sensors 1A and 2A are regarded as sin values respectively, and the sensor outputs V1B and V2B of the magnetic sensors 1B and 2B are respectively regarded as cos values. As shown in FIG. 8D, if the two cos waveforms at the time of viewing have a large twist of the torsion bar 34 and a phase difference, respectively.
As shown in (c), the calculated torque value becomes large.

FIG. 9 shows a Japanese Patent Application No. 2000-32 filed by the present applicant.
A change mode of the output voltage of the magnetic sensor 1A on the input shaft 31 side and the magnetic sensor 2A on the output shaft 32 side in the torque detection device for explaining the output correction (FIG. 3S6) of the magnetic sensor proposed in 6088 and described above. It is explanatory drawing which shows an example. The horizontal axis in the figure represents the rotation angle of the input shaft 31 facing the magnetic sensor 1A and the output shaft 32 facing the magnetic sensor 2A, and the solid line in the figure represents the output voltage of the magnetic sensor 1A on the input shaft 31 side. Similarly, the broken line indicates the output voltage of the magnetic sensor 2A on the output shaft 32 side.

As described above, when the five targets 20, 20, ... Are arranged side by side on the outer periphery of the target plate 2 attached to the input shaft 31 and the output shaft 32, the output voltage of the magnetic sensors 1A, 2A. Is an input shaft 31 and an output shaft 32
Is a region in which the rotation of 72 ° (= 360 ° / 5) is set as one cycle and linearly rises (or falls) while each first inclined portion 21 passes (hereinafter referred to as a first linear change region).
A region that changes non-linearly during the passage of each connecting portion between the first inclined portion 21 and the second inclined portion 22 adjacent to each other, and each second
A region (hereinafter referred to as a second linear change region) that linearly descends (or rises) while the inclined portion 22 passes, and each connection portion between the adjacent second inclined portion 22 and the first inclined portion 21 passes. The change mode which repeats the area which changes non-linearly during is shown.

Here, the magnetic sensors 1A, 1B and 2A, 2
As described above, B is attached with the phase shifted by an electrical angle of 90 ° in the circumferential direction of the target plate 2.
In FIG. 9, when the change modes of the output voltages of the magnetic sensor 1A and the magnetic sensor 2A are compared, the two show that the inclination angles in the respective first linear change regions and the inclination angles in the respective second linear change regions are different from each other. It can be seen that they are different from each other and that the midpoint voltage of each fluctuation range shown by the one-dot chain line in the figure is also different. Therefore, since the magnetic sensors 1A and 2A output different output voltages V1A and V2A for the same rotation angle θ _O , respectively, the input shaft 31 and the output shaft 3 which are obtained by using these output voltages V1A and V2A, respectively.
The accuracy of the rotation torque calculated based on the rotation angle of 2 and the difference between these rotation angles decreases. In FIG. 9, for convenience of explanation, the difference in output voltage of the magnetic sensors 1A and 2A is emphasized.

FIG. 10 shows a Japanese Patent Application No. 2000-3 filed by the applicant of the present application.
It is a flowchart which shows the setting operation | movement of the correction gain for correcting the output of the magnetic sensor of the torque detection apparatus proposed in 26088. The arithmetic processing unit 4 monitors the output voltage of the magnetic sensors 1A and 2A that are sequentially taken in to calculate the rotation angle and the rotation torque, and detects whether the detected target 20 is the first inclined portion 21 or not. It is determined whether or not it is the two-slope portion 22 (S31).

The arithmetic processing unit 4 detects the target being detected.
When it is determined that the portion 20 is the first inclined portion 21 (S
31), each of the input shaft 31 and the output shaft 32 has a first
Wait until it rotates by one of the inclined parts 21, 21, ...
(S32) When it is determined that one rotation has occurred,
Of the output voltage of the magnetic sensor 1A and the magnetic sensor 2A between
A preset rotation angle within the first linear change region
Output voltage V of the magnetic sensor 1A at both ends of the range Δθ
₁₁₁, V₁₁₂And the output voltage V of the magnetic sensor 2A_{twenty one 1}, V
₂₁₂Are calculated respectively (S33).

FIG. 11 shows the correction gain setting of the torque detection device.
It is explanatory drawing which shows a fixed operation | movement, and one target 20 passes.
Change of output voltage of magnetic sensor 1A, 2A during
Then, the change of the output voltage for one cycle is
The output voltage of the sensor 1A is shown by the solid line in the magnetic sensor 2A.
The output voltage is shown by broken lines. input
Each of the shaft 31 and the output shaft 32 has a first inclined portion 21,
While waiting for one rotation of 21, ... (S
32), the first linear shape of the magnetic sensors 1A and 2A shown in FIG.
The output voltage in the change area is referred to and the rotation angle range Δ
Both-end voltage V of θ ₁₁₁, V₁₁₂And V₂₁₁, V₂₁₂Wanted
(S33). The rotation angle range Δθ is the first linear
If the angle range is included in the change area, set it appropriately.
You can

Then, the arithmetic processing unit 4 applies the obtained voltage across both ends V ₁₁₁ , V ₁₁₂ and V ₂₁₁ , V ₂₁₂ (S33) to the following equation to obtain the sensor gains K ₁₁ and K _{11 of} the magnetic sensors 1A and 2A, respectively. K ₂₁ is calculated (S34). K ₁₁ = (V ₁₁₁ −V ₁₁₂ ) / Δθ (1) K ₂₁ = (V ₂₁₁ −V ₂₁₂ ) / Δθ (2) Sensor gains K ₁₁ and K calculated by these equations
_As shown in FIG. 11, reference numeral ₂₁ indicates the rate of change (slope) of the output voltage in the first linear change region of each magnetic sensor 1A, 2A.

Next, the arithmetic processing section 4 _applies the voltages V _1A11 , V _1A12 and V _1B11 , V _1B12 to the following equation,
The average sensor gain K _m1 in the first linear change region of both magnetic sensors 1A and 1B is calculated (S35). K _m1 = {(V ₁₁₁ −V ₁₁₂ ) / 2 + (V ₂₁₁ −V ₂₁₂ ) / 2} / Δθ = {(V ₁₁₁ −V ₁₁₂ ) + (V ₂₁₁ −V ₂₁₂ )} / 2 Δθ (3)

Average sensor gain calculated by this formula
K_m1Is the magnetic sensors 1A, 2 in the first linear change region.
A change rate of the average value of the output voltage, that is, one point in FIG.
The slope of the straight line L1 indicated by the chain line is shown. And
The arithmetic processing unit 4 calculates the calculated sensor gain K.₁₁, K_{twenty one}(S
34), and the calculated average sensor gain K_m1(S35)
Is applied to the following equation to obtain the magnetic sensor in the first linear change region.
Correction gain K for multiplying the actual output of 1A and 2A₁₀₁
And K ₂₀₁Are calculated respectively (S36). K₁₀₁= K_m1/ K₁₁      (4) K₂₀₁= K_m1/ K_{twenty one}      (5)

Correction gain K calculated by these equations
₁₀₁ and K ₂₀₁ are correction values for adjusting the sensor gains K ₁₁ and K ₂₁ unique to the magnetic sensors 1A and 2A to the average sensor gain K _m1 , respectively, and the correction values are set to the actual output voltages of the magnetic sensors 1A and 2A. The result obtained by multiplying the gains K ₁₀₁ and K ₂₀₁ is a point on the average characteristic indicated by the alternate long and short dash line in FIG. 11, and the difference in the output characteristic and the corresponding target 2
The error component included in the output voltage of the magnetic sensors 1A and 2A can be eliminated by the difference in the air gap between 0, 20 ...

When the arithmetic processing unit 4 determines that the detected part of the target 20 is the second inclined portion 22 (S31), each of the input shaft 31 and the output shaft 32 has the second inclined portion. It waits until it rotates by one of the parts 22, 22, ... (S37), and when it is determined that one rotation has occurred, the magnetic sensor 1A and the magnetic sensor 2A in the meantime.
Of the output voltage V ₁₂₁ , V ₁₂₂ of the magnetic sensor 1A and the output voltage V ₂₂₁ , of the magnetic sensor 1B at both ends of the rotation angle range Δθ within the second linear change region of the output voltage of
Each V ₂₂₂ is calculated (S38).

The output voltage in the second linear change region of the magnetic sensors 1A, 2A shown in FIG. 11 is referred to while waiting for one rotation of the second inclined portions 22, 22, ... (S37). , Voltage V ₁₂₁ , V across the rotation angle range Δθ
_122, V ₂₂₁ , and V ₂₂₂ are calculated (S38). still,
The rotation angle range Δθ can be appropriately set as long as it is within the second linear change region.

Then, the arithmetic processing section 4 applies the obtained voltages V ₁₂₁ , V ₁₂₂ and V ₂₂₁ and V ₂₂₂ (S38) to the following equations to obtain the sensor gains K ₁₂ and K _{12 of} the magnetic sensors 1A and 2A, respectively. calculating the K ₂₂ (S39). K ₁₂ = (V ₁₂₁ −V ₁₂₂ ) / Δθ (6) K ₂₂ = (V ₂₂₁ −V ₂₂₂ ) / Δθ (7) Sensor gains K ₁₂ and K calculated by these equations
_As is apparent from FIG. 11, ₂₂ indicates the rate of change (gradient) of the output voltage in the second linear change region of each magnetic sensor 1A, 2A.

Next, the arithmetic processing section 4 applies the voltages V ₁₂₁ , V ₁₂₂ and V ₂₂₁ , V ₂₂₂ to the following equation,
The average sensor gain K _m2 in the second linear change region of both magnetic sensors 1A and 2A is calculated (S40). K _m2 = {(V ₁₂₁ −V ₁₂₂ ) / 2 + (V ₂₂₁ −V ₂₂₂ ) / 2} / Δθ = {(V ₁₂₁ −V ₁₂₂ ) + (V ₂₂₁ −V ₂₂₂ )} / 2Δθ (8)

Average sensor gain calculated by this formula
K_m2Is the magnetic sensors 1A, 2 in the second linear change region.
A change rate of the average value of the output voltage, that is, one point in FIG.
The slope of the straight line L2 indicated by the chain line is shown. And
The arithmetic processing unit 4 calculates the calculated sensor gain K.₁₂, K_{twenty two}(S
39), and the calculated average sensor gain K_m2(S40)
Is applied to the following equation to obtain the magnetic sensor in the second linear change region.
Correction gain K for multiplying the actual output of 1A and 2A₁₀₂
And K ₂₀₂Are calculated respectively (S41). K₁₀₂= K_m2/ K₁₂    (9) K₂₀₂= K_m2/ K_{twenty two}    (10)

Correction gain K calculated by these equations
₁₀₂ and K ₂₀₂ are correction values for adjusting the sensor gains K ₁₂ and K ₂₂ specific to the magnetic sensors 1A and 2A to the average sensor gain K _m2 , respectively, and the correction values are added to the actual output voltages of the magnetic sensors 1A and 2A. The result obtained by multiplying the gains K ₁₀₂ and K ₂₀₂ is a point on the average characteristic indicated by the alternate long and short dash line in FIG. 11, and the difference in output characteristic and the corresponding target 2
The error component included in the output voltage of the magnetic sensors 1A and 2A can be eliminated by the difference in the air gap between 0, 20 ...

Correction gain K calculated by these equations
₁₀₂And K₂₀₂Also, the correction gain K_{Ten 1}And K₂₀₁Same as
, The sensor sensor unique to each of the magnetic sensors 1A and 2A
In K ₁₂, K_{twenty two}Is the average sensor gain K_m2To match
Is the correction value of the actual output voltage of the magnetic sensors 1A and 2A.
Correction gain K for pressure₁₀₂, K₂₀₂The result of multiplying is
It becomes a point on the average characteristic shown by the one-dot chain line in 11
Different force characteristics and corresponding targets 20, 20, ...
The magnetic sensors 1A and 2A due to the difference in air gap between
Error component contained in the output voltage of
It

The arithmetic processing unit 4 calculates the correction gains K ₁₀₁ , K ₂₀₁ , K ₁₀₂ , calculated by the operations of S31 to S41.
K ₂₀₂ is updated each time and stored (S42), and the process returns. The magnetic sensors 1B and 2B are also connected to the above S3.
Similar to the operations of 1 to S41, the arithmetic processing unit 4 calculates the correction gains K ₁₀₁ , K ₂₀₁ , K ₁₀₂ , and K _202, and updates and stores them each time, but the description is omitted.

The arithmetic processing unit 4 adds the correction gain K to the sensor output V1A (FIG. 3S4) of the A / D converted magnetic sensor 1A.
Magnetic sensor 2 multiplied by ₁₀₁ or K ₁₀₂ and A / D converted
The sensor output V2A (S4) of A is multiplied by the correction gain K ₂₀₁ or K ₂₀₂ , and the A / D converted sensor output V1B (S4) of the magnetic sensor 1B is multiplied by the correction gain K ₁₀₁ or K _102. Sensor output V of D / D converted magnetic sensor 2B
2B (S4) is multiplied by the correction gain K ₂₀₁ or K ₂₀₂ to correct each sensor output V1A, V2A, V1B, V2B (S6). In the above-described embodiment, the V-shaped or inverted V-shaped target is described, but the target is not limited to the V-shaped or inverted V-shaped target, and the same effect can be obtained even if the target is W-shaped, gear-shaped, or the like. It is possible to get

[0057]

According to the rotation angle detecting device of the first aspect of the present invention, it is possible to realize a rotation angle detecting device which does not require switching of the channel of the detecting means.

According to the rotation angle detecting device of the second aspect of the present invention, the respective results output by the detecting means can be accurately approximated to the sine function and the cosine function, respectively, and it is not necessary to switch the channel of the detecting means. An angle detection device can be realized.

According to the torque detector of the third invention,
It is possible to realize a torque detection device that does not need to switch the channel of the detection means.

According to the steering device of the fourth aspect of the present invention, it is possible to realize the steering device including the torque detection device of the third aspect.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration example of an embodiment of a rotation angle detection device and a torque detection device according to the present invention applied to a steering device for an automobile.

FIG. 2 is a development view in which an outer peripheral surface of a target plate is developed.

FIG. 3 is a flowchart showing operations of a rotation angle detection device, a torque detection device, and a steering device according to the present invention.

FIG. 4 is a waveform diagram for explaining the relationship between the output of the magnetic sensor and the sin waveform and the cos waveform.

FIG. 5 is an example of a graph of tan θ.

FIG. 6 is a graph for explaining a tan search table.

FIG. 7 is a flowchart showing a calculation operation of an angular difference between an input shaft and an output shaft.

FIG. 8 is an explanatory diagram showing operations of the angle detection device, the torque detection device, and the steering device according to the present invention.

FIG. 9 is an explanatory diagram for explaining output correction of a magnetic sensor.

FIG. 10 is a flowchart showing a correction gain setting operation for correcting the output of the magnetic sensor of the torque detection device.

FIG. 11 is an explanatory diagram showing a correction gain setting operation of the torque detection device.

[Explanation of symbols]

1A, 1B, 2A, 2B Magnetic sensor (first detection means or second detection means) 1 Sensor box 2 Target plate 3 Steering axis (rotary axis) 4 Arithmetic processing section (determination means) 4a sin approximation table (approximation means) 4b cos approximation table (approximation means) 4c tan search table (determination means) 20 target 30 steering wheel 31 input shaft (first shaft) 32 output shaft (second shaft) 34 torsion bar (connection shaft)

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G01L 5/22 G01L 5/22 3D033 // G01B 7/30 101 G01B 7/30 101B F term (reference) 2F051 AA01 AB05 AC01 BA03 2F063 AA35 AA36 BA30 BD03 CB04 CB05 CB08 DA01 DA05 DD05 GA54 GA64 KA01 LA11 LA12 LA16 LA19 LA22 LA23 LA24 LA25 LA29 LA30 2F069 AA83 BB40 GG04 GG06 TD04 BB09 GD21 JJ09 TD22 JJ09 JJ22 TT09 JJ09 JJ22 TT09 JJ09 JJ22 TT JJ09 JJ22 TT JJ09 JJ22 TT.

Claims (4)

[Claims] 1. One or a plurality of targets are provided on the rotating body so that the first detecting means adjacent to the rotating body outputs a detection signal as the rotating body provided on the rotating shaft rotates.
The second detection means outputs a detection signal different from the first detection means by a predetermined angle, and based on the detection signals respectively output by the first detection means and the second detection means, the first detection means of the rotating shaft or A rotation angle detection device for detecting a rotation angle from a second detection means, wherein one of the detection signals output by the first detection means and the second detection means is approximated to a sine function, and the other is approximated to a cosine function. Means for obtaining a tangent function based on the sine function and cosine function approximated by the approximating means, and means for obtaining an inverse function of the tangent function obtained by the means, wherein the inverse function obtained by the means is A rotation angle detecting device characterized in that the rotation angle is set. 2. The approximating means comprises two tables in which one and the other of the detection signals previously output by the first detecting means and the second detecting means are associated with the sine function and the cosine function, respectively. The rotation angle detecting device according to claim 1, wherein the table is referred to based on the respective detection signals output from the first detecting means and the second detecting means. 3. The torque applied to the first shaft is the torque applied to the first shaft and the second shaft.
A torque detecting device for detecting based on a twist angle generated in a connecting shaft that coaxially connects with a shaft, wherein the rotation angle detecting device according to claim 1 or 2 is attached to each of the first shaft and the second shaft. The torque detection device is characterized in that a difference between the rotation angles detected by the rotation angle detection device is set as the twist angle. 4. A first shaft connected to a steering wheel, a second shaft connected to a steering mechanism, a connecting shaft connecting the first shaft and the second shaft, and a steering torque applied to the first shaft. And a torque detecting device according to claim 3, wherein the steering shaft is detected based on a twist angle generated in the connecting shaft, and steering is assisted according to a steering torque detected by the torque detecting device. Device.