JP2002173045A - Electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low cost electric power steering device capable of detecting a steering column angle at a high resolution and a high accuracy without using a steering column angle sensor. SOLUTION: The electric power steering device is provided with a steering wheel angle sensor 11 for detecting a steering wheel angle; a motor angle sensor 8 for detecting a motor angle; a counter 9 for counting an output variation of the motor angle sensor 8; a steering torque sensor 10 for detecting a steering torque; and a CPU 20A for operating the steering column angle based on the output of the steering wheel angle sensor 11, the counter 9 and the steering torque sensor 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric power steering apparatus, and more particularly to an electric power steering apparatus for a vehicle in which an electric motor is operatively connected to a steering assembly via a gearbox to provide an assist torque to the steering assembly. The present invention relates to a steering device.

[0002]

2. Description of the Related Art FIG. 13 is a block diagram showing a conventional electric power steering apparatus disclosed in Japanese Patent Application Laid-Open No. 2000-203443. In the figure, 1 is a steering column, 2 is a steering wheel, 3 and 4 are wheels, 5 is a rack and pinion gear, 6 is a motor, 7 is a motor reduction gear (16.5: 1), 8 is a motor angle sensor, 9 Is a counter, 10 is a steering torque sensor, 11 is a steering wheel angle sensor, and 20 is a CPU.

Next, the operation will be described. The output change of the high-resolution motor angle sensor 8 capable of detecting the relative angle (output change at every predetermined angle) is counted by the counter 9, and the low-resolution steering wheel angle sensor 11 capable of detecting the absolute angle reaches a predetermined value. At this time, by resetting the counter value, the CPU 20 detects the steering wheel angle with high resolution from the counter value while removing accumulated errors.

In this electric power steering apparatus, θhdl = Gm * θm θhdl: steering wheel angle θm: motor angle
Gm: The motor reduction gear ratio is assumed. However, in reality, θhdl = Gm * θm + θts θts: twist angle of steering torque sensor θts = Tsens / Ktsens Tsen
s: steering torque Ktsens: spring constant of the steering torque sensor. Normally, θts changes in a range of about ± 3 degrees. However, since this conventional device ignores this, there is a problem that the steering wheel angle θhdl cannot be detected with high accuracy from the counter value.

FIG. 14 is a view similar to that of JP-A-2000-20.
1 is a configuration diagram illustrating a conventional electric power steering device disclosed in Japanese Patent No. 3443. The configuration of the steering wheel angle sensor 1 is different from the configuration of FIG.
1 is replaced by the steering column angle sensor 12, and the other configuration is the same.

Next, the operation will be described. The output change of the high-resolution motor angle sensor 8 capable of detecting the relative angle (output change at every predetermined angle) is counted by the counter 9 and the low-resolution steering column angle sensor 1 capable of detecting the absolute angle is provided.
When 2 has reached the predetermined value, the counter value is reset, so that the accumulated error is removed and the CPU 20 detects the steering column angle from the counter value with high resolution.

In this electric power steering apparatus, θcol = Gm * θm θcol: steering column angle θm: motor angle G
m: Motor reduction gear ratio. Unlike the device of FIG. 13, in this case, it is not necessary to consider the twist angle θts of the steering torque sensor 10, and the steering column angle θcol can be accurately detected from the counter value.

[0008]

However, in reality, as in the prior art apparatus shown in FIG.
It is costly and physically difficult to install a sensor that directly detects col, and it is generally considered that a steering wheel angle sensor is used instead of a steering column angle sensor.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and does not require a sensor for directly detecting a costly and physically difficult steering column angle. It is an object of the present invention to provide an inexpensive electric power steering device that can accurately detect a steering wheel angle.

[0010]

An electric power steering apparatus according to the present invention has a steering wheel angle detecting means for detecting a steering wheel angle, a motor angle detecting means for detecting a motor angle, and the motor angle detecting means. Counter means for counting output changes of the means, steering torque detecting means for detecting steering torque, and calculating means for calculating a steering column angle based on outputs of the steering wheel angle detecting means, counter means and steering torque detecting means. It is provided with.

According to a second aspect of the present invention, in the electric power steering apparatus according to the first aspect, the calculating means resets a counter value of the counter means when the steering torque and the steering wheel angle are at predetermined values. Then, the steering column angle is calculated based on the counter value.

According to a third aspect of the present invention, in the electric power steering apparatus according to the first aspect, the calculating means calculates a torsion angle of the steering torque sensor from the steering torque and a known spring constant specific to the steering torque sensor. And
When the correction value obtained by subtracting the twist angle from the steering wheel angle is a predetermined value, the counter value of the counter means is reset, and the steering column angle is calculated based on the counter value.

According to a fourth aspect of the present invention, in the electric power steering apparatus according to the second or third aspect, the calculating means calculates a torsion angle of the steering torque sensor based on the steering torque and a known spring constant specific to the steering torque sensor. Is calculated, and the steering column angle is calculated by adding the steering column angle to the torsion angle.

An electric power steering apparatus according to a fifth aspect of the present invention is the electric power steering apparatus according to any one of the second to fourth aspects,
The calculating means calculates the offset amount between the steering column angle and the motor angle by １ ／ of the resolution of the motor angle sensor.
And the steering column angle is calculated based on the counter value in consideration of the offset amount.

According to a sixth aspect of the present invention, there is provided an electric power steering apparatus according to any one of the second to fifth aspects.
The calculating means calculates the steering column angle from the ratio of the time from the last count-up before the counter means is reset to the reset, and the time from the reset of the counter means to the first count-up. The offset amount of the motor angle is calculated, and the steering column angle is calculated based on the counter value in consideration of the calculated offset amount.

An electric power steering apparatus according to a seventh aspect of the present invention is the electric power steering apparatus according to any one of the first to sixth aspects,
A low-pass filter is provided between the steering torque detecting means and the calculating means.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. Embodiment 1 FIG. FIG. 1 is a configuration diagram showing Embodiment 1 of the present invention. In the figure, 1 is a steering column, 2
Is the steering wheel, 3 and 4 are the wheels, 5 is the rack
A pinion gear 6 is a motor for providing torque assistance to a driver, and is connected to the steering column 1 via a motor reduction gear 7 (16.5: 1). 8 is a motor angle sensor as a motor angle detecting means, 9 is a counter as a counter means, 10 is a steering torque sensor as a steering torque detecting means, 11 is a steering wheel angle sensor as a steering wheel angle detecting means, and 20A is a counter 9 And a CPU as an arithmetic means to which the outputs of the steering torque sensor 10 and the steering wheel angle sensor 11 are input.

As shown in FIG. 2A, the motor 6 includes a three-phase permanent magnet brushless motor including a rotor portion (rotor magnet 100) and a stator portion, and three Hall effect sensors A, B, and C. And a motor angle sensor 8.

The motor angle sensor 8 is installed around the rotor magnet 100 of the motor 6, and detects the rotation angle of the rotor. Each of the sensors A, B, and C outputs whether the rotor magnet 100 has the N pole or the S pole within the detection range of each sensor. When the outputs of the Hall effect sensors A, B, and C are combined, six types of outputs (S1 to S6) (see FIG. 2B) are obtained while the motor 6 rotates 120 degrees. 120
When the motor angle is divided into six, the angle can be converted into the steering column angle via the motor reduction gear 7 by the following equation (1).
The resolution is higher by 1.2 degrees.

120 degrees / 6 / 16.5 = 1.2 degrees (Equation 1)

However, the output of the motor angle sensor 8 does not indicate an absolute angle from a predetermined position. When the rotation continues in the same direction, the sensor output sequence of S1 to S6 is repeated every 120 degrees. The counter 9 calculates the S1
This is counter means for counting the output change in S6.

The steering torque sensor 10 is for measuring the torque generated by the driver operating the steering wheel 2, and the output is used for controlling the current applied to the motor 6.

Next, the operation will be described with reference to FIG. When the driver performs steering, the steering torque sensor 10 detects the steering torque Tsens, and the motor 6
Current is supplied to the motor 6, and the rotor of the motor 6 rotates. When the rotor rotates, the output of the motor angle sensor 8 changes (S1).
To S6). The counter 9 counts up when the output of the motor angle sensor 8 changes in the forward direction, for example, S1 → S2, S2 → S3, S3 → S4..., S1 → S6, S
If it changes in the reverse direction of 6 → S5, S5 → S4,...

The steering wheel angle sensor 11 always detects the steering wheel angle θhdl. While performing the above operation, the steering torque Tsens is 0 (Yes in step ST1), and the steering wheel angle θh
If dl is 0 (Yes in Step ST2), the counter 9 is reset (Step ST3), and the steering column angle θcol is detected from the counter value (ie, a value of 0) (Step ST4). On the other hand, the steering torque Tsens is 0
(Step ST1 is No) or the steering wheel angle θhdl is not 0 (step ST2 is N)
In the case of o), the steering column angle θcol is detected from the counter value at that time (step ST4).

Here, the steering torque Tsens is 0
However, if the value is negligibly small, 0
It is not necessary. Also, the steering wheel angle θhdl
Is assumed to be 0, but the predetermined steering wheel angle θ
The counter 9 may be reset at hdl to detect a steering column angle θcol relative to a predetermined steering wheel angle θhdl.

As described above, in this embodiment, when the steering torque Tsens is 0 (not limited to 0) and the steering wheel angle sensor θhdl is a predetermined value, the counter value is reset, and the steering value is reset from the counter value. Since the column angle θcol is detected, when the steering torque Tsens is 0, the twist angle θts of the steering torque sensor is 0 and can be ignored. Thus, the steering column angle θcol can be detected with high resolution and high accuracy from the count value without using the steering column angle sensor.

Embodiment 2 FIG. This embodiment is different from Embodiment 1 in the method of resetting the counter 9. Therefore, the circuit configuration is the same as that of the first embodiment, and the description is omitted. Next, the operation will be described with reference to FIG. Steering torque Tsens
And a spring constant Ktsen specific to a known steering torque sensor.
The torsion angle θts of the steering torque sensor 10 is calculated from s (the amount of torque per unit torsion angle) (step ST).
11). Next, the torsion angle θts of the steering torque sensor 10 is subtracted from the steering wheel angle θhdl to obtain a correction angle θcomp (step ST12). When the correction angle θcomp is 0 (Yes in step ST13), the counter value is reset (step ST13). (Step ST14), the steering column angle θcol is detected from the counter value (ie, a value of 0) (Step ST15). On the other hand, if the correction angle θcomp is not 0 (No in step ST13), the steering column angle θcol is detected from the counter value at that time (step ST15).

As described above, in the present embodiment, the torsion angle θts of the steering torque sensor is calculated from the steering torque Tsens and the known spring constant Ktsens (the amount of torque per unit torsion angle) inherent in the steering torque sensor. When the correction value θcomp obtained by subtracting the twist angle θts of the steering torque sensor from the steering wheel angle θhdl is a predetermined value, the counter value is reset, and the steering column angle θcol is detected from the counter value, so that the steering torque Tsens Is zero, the torsion angle θts of the steering torque sensor is zero and can be ignored. Thus, the steering column angle θcol can be detected with high resolution and high accuracy from the count value without using the steering column angle sensor.

Embodiment 3 In this embodiment, the steering wheel angle θhdl is detected after detecting the steering column angle θcol in the first and second embodiments. Therefore, the circuit configuration is the same as that of the first embodiment, and the description is omitted. Next, the operation will be described with reference to FIG. Steering torque Tsens
And a spring constant Ktsen specific to a known steering torque sensor.
The torsion angle θts of the steering torque sensor 10 is calculated from s (the amount of torque per unit torsion angle) (step ST).
21). Next, the correction angle θcomp is obtained by subtracting the twist angle θts of the steering torque sensor 10 from the steering wheel angle θhdl (step ST22). When the correction angle θcomp is 0 (Yes in step ST23), the counter value is reset (step ST23). In step ST24, the steering column angle θcol is detected from the counter value (ie, a value of 0) (step ST25). On the other hand, if the correction angle θcomp is not 0 (No in step ST23), the steering column angle θcol is detected from the counter value at that time (step ST25).

Next, based on the steering torque Tsens and a known spring constant Ktsens (torque amount per unit torsion angle) inherent in the steering torque sensor, the steering torque sensor 10
Is calculated (step ST26), the torsion angle θts of the steering torque sensor 10 is added to the steering column angle θcol, and the steering wheel angle θh is calculated.
dl is detected (step ST27).

When the torsion angle θts of the steering torque sensor 10 is calculated in the process of detecting the steering column angle θcol as in the second embodiment, the value may be added to the steering wheel angle θhdl. Good.

As described above, in the present embodiment, the torsion angle θts of the steering torque sensor is calculated from the steering torque Tsens and the known spring constant Ktsens (torque amount per unit torsion angle) inherent in the steering torque sensor. The torsion angle θts of the steering torque sensor is added to the steering column angle θcol detected from the counter value to detect the steering wheel angle θhdl. That is, the torsion angle of the steering torque sensor is subtracted from the high-resolution steering column angle, and Since the wheel angle is calculated, the steering wheel angle θhdl can be detected with high resolution.

Embodiment 4 FIG. In the first to third embodiments, when detecting the steering column angle θcol from the counter value, θcol = counter value * 1.2 degrees, but in the present embodiment, when the counter value is a positive value, The following equation (2) is used. In the case of a negative value, the following equation (3) is used. Offset amount θoff in the present embodiment
set is half of the angle resolution of the motor angle sensor (0.6 degrees)
It is.

Θ col = (counter value−1) * 1.2 degrees + θ offset (0.6 degrees) (Equation 2) θ col = counter value * 1.2 degrees + θ offset (0.6 degrees) (Equation 3)

The circuit configuration is the same as that of the first embodiment.
Therefore, the description is omitted. Next, the operation will be described with reference to FIG. Steering torque Tsen
s and a spring constant Ktse specific to a known steering torque sensor.
The torsion angle θts of the steering torque sensor 10 is calculated from ns (the amount of torque per unit torsion angle) (step S).
T31). Next, the torsion angle θts of the steering torque sensor 10 is subtracted from the steering wheel angle θhdl to obtain a correction angle θcomp (step ST32).
In this case (Yes in step ST33), the counter value is reset (step ST34) and the process proceeds to step ST35, and the correction angle θcomp is not 0 (step ST33).
If 23 is No), the process directly proceeds to step ST35.

In step ST35, it is determined whether the counter value is a positive value, a negative value, or 0, and the steering column angle θcol is obtained by the above equation 2 when the counter value is a positive value. Value (step ST3
6) If the value is a negative value, the value is determined by the above equation 3 (step ST37); if the value is 0, the value is set to 0 (step ST37).
38).

By using the steering column angle θcol obtained in steps ST36 to ST38 and performing the same processing as in steps ST26 and ST27 in the third embodiment, the steering wheel angle θh
It is also possible to use k for detecting dl.

Accordingly, in the first to third embodiments, the error due to the angular resolution of the motor angle sensor is 0 to 1.2 degrees, whereas in the present embodiment, the error is -0.6 degrees to +0.6 degrees.
The steering column angle θcol and the steering wheel angle θhdl can be detected with higher accuracy by reducing the absolute value of the error.

As described above, in the present embodiment, the offset amount θ between the steering column angle θcol and the motor angle θm
The offset is fixed to 1/2 of the resolution of the motor angle sensor, and the steering column angle θcol is detected from the counter value in consideration of the offset amount θoffset, that is, the offset amount θoffset between the steering column angle θcol and the motor angle θm is considered. Therefore, the steering column angle θcol and the steering wheel angle θhdl can be detected with higher accuracy.

Embodiment 5 In the fourth embodiment, θ
The offset is half of the angular resolution of the motor angle sensor (0.
6 degrees), but in the present embodiment, θoff
set detection method is different. FIG. 7 is a configuration diagram showing a fifth embodiment of the present invention. In the figure, 13 is θoff
set detecting means, 14 is a timer, 20B is a steering torque sensor 10, a steering wheel angle sensor 11, and θ
The CPU as an arithmetic unit to which the output of the offset detecting unit 13 is input. The other configuration is the same as that of the first embodiment, and the description is omitted.

In this case, the timer 14 detects the time interval at which the counter 9 changes (counts up, counts down, and resets), and stores the counter value and the timer value in the θoffset detecting means 13.
ffset is detected. The resolution of the timer 14 is sufficiently larger than the count-up interval of the counter 9.

Next, the operation will be described with reference to FIGS. Note that the flowchart for detecting the steering column angle θcol is the same as that in the above-described fourth embodiment, and thus the description thereof will be omitted. FIG. 8 is a flowchart showing the operation of the θ offset detecting means 13.

The .theta.offset detecting means 13 detects the time interval between changes (count-up, count-down, reset) of the counter 9 by the timer 14 (steps ST41 and ST42), and stores the counter value and the timer value (step ST43). . As shown in FIG. 9 and FIG. 10, the number of data stored by the θ
In this example, numbers are assigned in order from the latest one. (Data with a data number of 5 or more may be deleted.)

The θ offset detecting means 13 clears the timer after storing the counter value and the timer value (step ST44), then checks the past four changes in the counter value, and checks the data 4-1 in the order of data 4-1. "-1,0,
It is checked whether the order changes in the order of "1, 2," or "1, 0, -1, -2" (step ST45). Here, “−1, 0, 1, 2” and “1, 0, −1, −2” indicate that the steering column has passed the origin from left to right or right to left. When these patterns are detected, the θoffset detecting means 13 outputs the data number 1
It is determined whether the timer value of the data number 2, the timer value of the data number 2 + the timer value of the data number 3, and the timer value of the data number 4 are the same (step ST46). If they are substantially the same (the difference is equal to or less than the predetermined value), then θoffset is detected (step ST47). The fact that they are the same indicates that the steering column has passed the origin at a constant speed from left to right or right to left.

When detecting θ offset, when the counter value is a change pattern of “−1, 0, 1, 2”, the timer value of data number 3 is T 1, the timer value of data number 2 is T 2, When the value is a change pattern of “1, 0, −1, −2”, the timer value of data number 2 is T1 and the timer value of data number 3 is T2. From Equation 4 below, θ
Offset is detected.

Θoffset = T2 / (T1 + T2) * 1.2 degrees (Equation 4)

FIG. 11 substantially shows the state of equation (4). Note that this detected θoffset is used as θoffset in steps ST36 and ST37 in FIG.
By performing the same processing as in steps ST26 and ST27 in the third embodiment using the steering column angle θcol determined in steps ST36 to ST38.
It is also possible to detect dl.

Therefore, in the present embodiment, the offset amount θoffset is accurately detected from the ratio between T1 and T2, so that the steering column angle θcol and the steering wheel angle θ
hdl can be detected.

As described above, in the present embodiment, the time T1 from the last count-up (countdown) before reset to the reset, and the time T1 from the reset to the first count-up (countdown) after reset. From the ratio of the time T2, the steering column angle θcol
And the offset amount θoffset between the motor angle θm and the detected offset amount θoffset,
Since the steering column angle θcol is detected from the counter value, the steering column angle θcol and the motor angle θm are detected.
, The steering column angle θcol and the steering wheel angle θhdl can be detected with high accuracy.

Embodiment 6 FIG. In the present embodiment, the steering torque Tsens of the first to fifth embodiments is
It is used after passing through a low-pass filter (not shown) provided between CPU 0 and CPU 20A or 20B. FIG. 12 shows the steering torque Tsen before and after the low-pass filter.
This shows the state of s. From this figure, it can be seen that the noise of the steering torque Tsens has been removed by using the low-pass filter. An averaging process having the same effect may be used.

As described above, in this embodiment, the noise of the steering torque Tsens can be removed by passing the steering torque Tsens through the low-pass filter, and the steering column angle θcol and the steering wheel angle θhdl can be increased from the counter value. Can be detected with high accuracy. In addition,
In the above embodiment, the resolution of the motor angle sensor is set to 1.2.
Although the degree is described as a degree, the present invention is not limited to this, and the description of “1.2 degrees” in the embodiment may be changed according to the resolution of each motor.

[0052]

As described above, according to the first aspect of the present invention, the steering wheel angle detecting means for detecting the steering wheel angle, the motor angle detecting means for detecting the motor angle, and the output of the motor angle detecting means. Counter means for counting changes, steering torque detecting means for detecting steering torque, and calculating means for calculating a steering column angle based on outputs of the steering wheel angle detecting means, counter means and steering torque detecting means. So
There is an effect that the steering column angle and the steering wheel angle can be detected with high resolution and high accuracy.

According to the second aspect of the present invention, the calculating means resets the counter value of the counter means when the steering torque and the steering wheel angle are at predetermined values, and performs steering based on the counter values. Since the column angle is calculated, the steering column angle can be detected with high resolution and high accuracy without using a steering column angle sensor.

According to the third aspect of the present invention, the calculating means calculates a torsion angle of the steering torque sensor from the steering torque and a spring constant specific to a known steering torque sensor, and calculates the torsion angle to the steering wheel. When the correction value obtained by subtracting from the angle is a predetermined value, the counter value of the counter means is reset and the steering column angle is calculated based on the counter value, so that the steering can be performed without using a steering column angle sensor. Since the column angle can be detected with high resolution and high accuracy, and the counter means can be reset even when the steering torque is not 0, there is an effect that the detection can be performed with higher accuracy.

According to the invention of claim 4, the calculating means calculates a torsion angle of the steering torque sensor from the steering torque and a spring constant specific to a known steering torque sensor, and calculates the torsion angle of the steering column. Since the steering wheel angle is calculated by adding the angles, the steering wheel angle can be detected with high resolution.

According to the fifth aspect of the present invention, the calculation means fixes the offset amount between the steering column angle and the motor angle to の of the resolution of the motor angle sensor, and takes the offset amount into consideration. Since the steering column angle is calculated based on the counter value, there is an effect that the steering column angle and the steering wheel angle can be detected with higher accuracy.

According to the invention of claim 6, the calculating means determines the time from the last count up before the counter means is reset to the time when the counter means is reset, and the first time after the counter means is reset. The offset amount between the steering column angle and the motor angle is calculated from the ratio of the time until counting up, and the steering column angle is calculated based on the counter value in consideration of the calculated offset amount. This has the effect that the steering column angle and the steering wheel angle can be detected.

According to the seventh aspect of the present invention, since a low-pass filter is provided between the steering torque detecting means and the calculating means, noise of the steering torque is removed to further reduce the steering column angle and the steering wheel angle. There is an effect that detection can be performed with high accuracy.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram for explaining a motor according to the first embodiment of the present invention;

FIG. 3 is a flowchart for explaining the operation of the first embodiment of the present invention;

FIG. 4 is a flowchart for explaining an operation according to the second embodiment of the present invention;

FIG. 5 is a flowchart for explaining the operation of the third embodiment of the present invention;

FIG. 6 is a flowchart for explaining the operation of the fourth embodiment of the present invention;

FIG. 7 is a configuration diagram showing a fifth embodiment of the present invention.

FIG. 8 is a flowchart for explaining the operation of the fifth embodiment of the present invention;

FIG. 9 is a diagram for describing an operation according to the fifth embodiment of the present invention;

FIG. 10 is a diagram for describing an operation according to the fifth embodiment of the present invention;

FIG. 11 is a diagram for explaining the operation of the fifth embodiment of the present invention;

FIG. 12 is a diagram for explaining an operation of the sixth embodiment of the present invention;

FIG. 13 is a configuration diagram showing a conventional electric power steering device.

FIG. 14 is a configuration diagram showing another example of a conventional electric power steering device.

[Explanation of symbols]

1 steering column, 2 steering wheel,
6 motor, 8 motor angle sensor, 9 counter, 10
Steering torque sensor, 11 steering wheel angle sensor, 13 θoffset detecting means, 14 timer,
20A, 20BCPU.

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (Reference) B62D 119: 00 B62D 119: 00 (72) Inventor Tomoyuki Inoue 2-3-2 Marunouchi 2-chome, Chiyoda-ku, Tokyo Mitsubishi Electric Co., Ltd. In-company (72) Inventor Chiaki Fujimoto 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Inventor Takayuki Kifu 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation F term (reference) 2F069 AA86 BB21 DD19 EE01 EE23 GG06 HH30 JJ17 NN04 NN08 3D032 CC30 DA03 DA15 DA63 EA01 EB04 3D033 CA02 CA16 CA17

Claims (7)

[Claims] 1. A steering wheel angle detecting means for detecting a steering wheel angle, a motor angle detecting means for detecting a motor angle, a counter means for counting an output change of the motor angle detecting means, and a steering for detecting a steering torque. An electric power steering apparatus comprising: a torque detection unit; and a calculation unit that calculates a steering column angle based on outputs of the steering wheel angle detection unit, the counter unit, and the steering torque detection unit. 2. The method according to claim 1, wherein said calculating means resets a counter value of said counter means when said steering torque and said steering wheel angle are predetermined values, and calculates a steering column angle based on said counter value. The electric power steering device according to claim 1, wherein 3. A correction value obtained by calculating a torsion angle of the steering torque sensor from the steering torque and a spring constant specific to a known steering torque sensor, and subtracting the torsion angle from the steering wheel angle. When is a predetermined value, reset the counter value of the counter means,
2. The electric power steering apparatus according to claim 1, wherein a steering column angle is calculated based on the counter value. 4. The calculating means calculates a twist angle of the steering torque sensor from the steering torque and a known spring constant specific to the steering torque sensor, and adds the steering column angle to the twist angle to obtain a steering wheel angle. The electric power steering apparatus according to claim 2, wherein the calculation is performed. 5. The arithmetic means fixes an offset amount between the steering column angle and the motor angle to の of a resolution of the motor angle sensor, and takes into account the offset amount and calculates a steering column angle based on the counter value. The electric power steering apparatus according to any one of claims 2 to 4, wherein? 6. The arithmetic means has a ratio of a time from the last count-up before the counter means is reset to a reset, and a time from the reset of the counter means to the first count-up. And calculating the steering column angle based on the counter value in consideration of the calculated offset amount, taking into account the calculated offset amount. An electric power steering device as described in the above. 7. The electric power steering apparatus according to claim 1, wherein a low-pass filter is provided between said steering torque detecting means and said calculating means.