JP2001278084A - Motor-driven power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor-driven power steering device capable of always generating moderate handle return torque from when a driver tries to start a vehicle. SOLUTION: A handle return torque TR is determined according to the steering speed ωH at least before the handle neutral position Θ0 which is a learning result of a neutral position learning part 24 is output once at first. The steering speed ωH is calculated according to the steering torque π and the motor rotating angle θM by a steering speed estimating part 242. When the handle return torque TR is thus determined according to the steering speed ωH, even in the control dead zone, a desired handle return torque can be output. At least after the first learning is completed, more desirably after the accuracy of the learned handle neutral position Θ0 is improved enough, the subsequent control carries out the handle return control according to the steering angle θH which can exhibit satisfactory handle return performance even in a low-friction road surface such as a frozen road or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering mechanism having a motor for applying torque to a steering shaft or a steering gear of a vehicle, and an electric power steering apparatus having a control device for controlling the driving of the motor. In particular, the present invention relates to the above-described control device that has a function of learning a neutral position of steering wheel steering and performs steering wheel return control.

[0002]

2. Description of the Related Art An electric power steering apparatus having a function of learning a neutral position of a steering wheel and performing a steering wheel return control is disclosed in, for example, Japanese Patent Laid-Open Publication No.
-132845: Electric power steering with learning function "and the like are generally known.

[0003] Figure 7 is a block diagram illustrating a functional configuration of the steering wheel return torque computing unit has a neutral position learning function carried out by the above prior art, each symbol in the figure, V _n is the vehicle speed, tau Is the steering torque of the steering wheel, θ _H
Is the steering wheel rotation angle input from the external steering angle sensor,
Handle neutral position theta _O was learned, it illustrates T _R is wheel return torque (command value), respectively.

[0004] As described above, the above-mentioned prior art learns the neutral position of the steering angle under "conditions in which the vehicle travels straight" which can be determined from the vehicle speed condition, the steering torque condition, the steering angle condition, and the like. By gradually increasing the accuracy of the neutral position by a predetermined statistical operation and performing the steering wheel return control based on the steering angle, it is intended to sufficiently secure the steering wheel return performance particularly at low speed traveling. .

[0005]

However, in the above-mentioned prior art, the neutral position Θ _O of the steering angle is learned by learning.
Although it is possible to gradually increase the accuracy of over a long period of time, at least at the beginning of this learning,
The width of the control dead zone has to be set very wide at about ± 15 °. Therefore, at least until the above-mentioned “condition for the vehicle to go straight” is fulfilled a predetermined number of times, the steering wheel is not controlled in the control dead zone at all. There was a problem that the return performance could not be secured.

[0006] The function of the power steering is originally required particularly during the running period from the time when the driver tries to start the vehicle to the time when such "the condition for the vehicle to go straight" is satisfied. Due to the large number, this problem must be said to be extremely serious in generating the steering wheel return torque.

Further, in the above prior art, as shown in a graph of T _R ′ in FIG. 7, an example of setting the steering wheel return torque, in order to ensure a sufficient steering wheel return performance outside the above-mentioned control dead zone, As the width of the control dead zone becomes wider, the value of T _R ′ must be rapidly changed near (outside) the boundary of the control dead zone. However, if such a setting is made, the steering wheel return torque suddenly increases immediately after the steering angle escapes from the control dead zone, causing a problem that a great sense of discomfort occurs in steering. This problem, although the accuracy of the neutral position theta _O gradually becomes possible eliminate as gradually increases, inevitably noticeable, especially in the learning beginning like.

Further, in the conventional techniques described above, for the neutral position theta _O of accuracy of the steering angle of learning beginning like is very low, left and right symmetry of the steering wheel return torque T _R are particularly accurate in learning beginning like Is not guaranteed. Therefore, when the error of the neutral position theta _O is large, the steering feeling of greater skewed asymmetrical to one (handle return torque) will be realized, undesirable in terms of operation stability.

In the above prior art, a rotation angle sensor externally provided near the reduction gear is used as the steering angle sensor. However, when the steering angle sensor is configured as described above, the number of parts and the material The cost cannot be reduced, causing a problem in terms of production cost.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an electric motor capable of generating an appropriate steering wheel return torque at all times when a driver tries to start a vehicle. It is an object of the present invention to provide a power steering device, and to provide an inexpensive electric power steering device that can provide the same steering feeling as a hydraulic power steering device.

[0011]

Means for Solving the Problems To solve the above problems,
For this purpose, the following measures are effective. That is, the first means
Is the steering shaft or steering
Steering mechanism with motor for applying torque to gear
And a control device for driving and controlling the motor.
In the power steering device, the vehicle speed V_n,
Steering torque τ exerted on the steering wheel by the driver
The steering angle θ of the steering wheel when_H
Neutral position to learn the neutral position according to the predetermined statistical operation
Learning means and a steering angle θ based on the neutral position._HBased on
Handle return torque T_RFirst handle to calculate
Return control means and the rotational angular velocity ω of the motor _MBased on c
Tundle return torque T_RHandle return control that calculates
And neutral means at least by the neutral position learning means.
Until position learning is completed once, return the second handle.
Handle return torque T_RTo determine
And

The second means includes a steering mechanism having a brushless DC motor having a built-in rotation angle sensor for synchronization for applying torque to a steering shaft or a steering gear of the vehicle, and driving the motor. An electric power steering device having a control device for controlling the steering angle is provided with a steering angle estimating means for estimating the steering angle θ _H of the steering wheel based on the output signal of the rotation angle sensor.

The third means is an electric power steering apparatus having a steering mechanism having a motor for applying torque to a steering shaft or a steering gear of a vehicle, and a control device for controlling the driving of the motor. , neutral position learning speed of the vehicle v, and the driver learns accordance neutral position predetermined statistical operation of the steering angle theta _H of the steering wheel in satisfying "vehicle straight ahead condition" steering torque τ is predetermined on relative to the handle Means and a steering wheel return torque T _R based on the steering angle θ _H based on the neutral position.
Steering wheel return control means, and steering state determination means for determining the steering state of the steering wheel based on the steering torque τ, further, in the handle return control means, according to the steering state, during steering or turning operation suppressing steering wheel return torque T _R so as not to reduce the assist torque to the steering, the back time letting go or steering is to comprise a steering wheel return torque limiting means to maintain or adjust the steering wheel return torque T _R.

A fourth means is the steering device according to the third means, further comprising a steering mechanism having a brushless DC motor having a built-in rotation angle sensor for synchronization, and a steering mechanism for steering the steering wheel based on an output signal of the rotation angle sensor. Steering angle estimating means for estimating the angle θ _H.

Further, the fifth means includes the second to fourth means described above.
In any one means, when the vehicle speed V _n of the vehicle, and the steering torque τ on the driver against the steering wheel satisfy the "vehicle straight ahead condition" predetermined steering angle of the steering wheel theta _H
A neutral position learning means for learning the neutral position according to predetermined statistical operation, a first handle return control means for calculating the steering wheel return torque T _R based on the neutral position in the steering angle theta _H as a reference, the rotational angular speed of the motor and a second handle return control means for calculating a torque T _R back wheel based on omega _M, until learning the neutral position by at least a neutral position learning means is completed once, the second handle return control means handle return is to determine the torque T _R.

[0016] The sixth means may be the first or the fifth one.
In the means, after the neutral position by the neutral position learning means learning is completed, the steering wheel return torque T _R is to determine the first wheel return controlling means. With the above means, the above-mentioned problem can be solved.

[0017]

[Action and Effect of the Invention] When the neutral position theta _O of accuracy of the steering angle is very low, i.e., as the neutral position by the neutral position learning means learning is until the completion of at least one, as shown in FIG. 7 However, since the width of the control dead zone is considerably large, the above-described problem occurs at the beginning of learning. However,
If the first means of the present invention is used, in such a case, the steering wheel return torque T _R can be determined based on the motor rotation angular velocity ω _M (or the steering speed ω _H or the related value thereof). when the steering angle theta _H is located in the control dead zone, i.e., in the learning beginning or the like of the neutral position, approximately it is possible to generate a desired steering wheel return torque T _R.

Further, if the second means of the present invention is used, the electric power steering apparatus does not need to have an external rotation angle sensor, so that the number of parts can be reduced, the production efficiency can be improved, and the production efficiency can be improved. Costs can be reduced.

Further, if the third means of the present invention is used, the steering wheel returning torque T _R can be obtained even when the driver performs the steering wheel returning operation slowly (or weakly) from the state where the steering wheel is turned at the time of low speed traveling. Is effective, so that the driver can obtain a steering feeling substantially similar to that of the conventional hydraulic power steering device even when the steering wheel returning operation is performed.

Further, if the fourth or fifth means of the present invention is used, the above-mentioned functions and effects can be effectively (complexly) obtained by effectively combining the above-mentioned means of the present invention. In addition, it is possible to obtain an electric power steering device that can always generate an appropriate steering wheel return torque, and it is also possible to reduce the cost of an electric power steering device that can provide the same steering feeling as a hydraulic power steering device.

Further, if the sixth means of the present invention is used, it is possible to sufficiently secure the handle returning performance even on a low friction road surface such as an icy road, and so-called overshoot in which the steering wheel returns excessively. The phenomenon can also be avoided.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on specific embodiments. However, the present invention is not limited to the embodiments described below. FIG. 1 is a hardware configuration diagram of an electric power steering apparatus 100 according to the present embodiment.

A steering wheel (steering wheel) 11 is attached to one end of the steering shaft 10.
The other end has a pinion shaft 13 that is mounted on a gear box 12.
Are combined. The pinion shaft 13 is mounted on the gearbox 1
Although not shown, both ends of the rack shaft 14 are connected to steering wheels (not shown) via ball joints or the like. Further, a brushless DC motor M (hereinafter, simply referred to as “motor M”) for applying assist torque is connected to the steering shaft 10 via two gears 17.

The DC motor M has a motor control device 1
The motor drive currents iu and i for the three phases U, V, and W are output from the ten drive circuits 113 via the current detector 115.
v and iw are supplied. Further, the steering shaft 1
0 to the steering wheel (handle) from the driver
A torque detector 15 for detecting the magnitude and direction (steering torque τ) of the manual steering force applied to the motor 11
Is provided.

The motor M has a built-in resolver R / D (rotation angle sensor) for detecting the rotation angle of the motor M, and the CPU 111 controls the phase n of the motor M output by the resolver R / D. 6-bit integer information (0 ≦ n <6
3). One unit is π / 32 radians. ) Enter the rotation angle of the motor M theta _M (phase: calculating a 0 ≦ θ _M <2π). The resolver R / D has a built-in counter (not shown) for counting the rotation angle of one unit.
Increases when rotated in a predetermined direction, and decreases when rotated in the opposite direction. n is a numerical value that overflows or underflows each time the motor makes one revolution.

The motor control device 110 includes a CPU 111,
ROM 112b, RAM 112a, drive circuit 113, input interface (IF) 114, current detector 115
And so on. The drive circuit 113 includes a battery (not shown), a PWM converter, a PMOS drive circuit, and the like, and supplies power to the motor M with a drive current of a sine wave by chopper control.

[0027] CPU111 of the motor control device 110, the above and phase n, the torque sensor 15 is used for detecting the steering torque τ of the steering wheel, the output signal from the speedometer 50 and the like to be used for calculation of the vehicle speed V _n (Measured value) is input via an input interface (IF) 114. CP
U111 determines a torque value (command torque T) to be output by the motor M based on a predetermined torque calculation from these input values, and further determines each current of the d-axis and the q-axis based on the command torque T. The command value (id ^* , iq ^* ) is determined.
However, in the present embodiment, “id ^* = 0” is set.

FIG. 2 is a block diagram showing a logical configuration of the motor control device 110 for controlling the driving of the motor M according to the present embodiment. 2 is a control block that determines the q-axis current command value iq ^* based on the command torque T, and is mainly composed of an iq ^* -T map (table data) and the like. .

The command torque calculating section 200 includes an angle detecting section 3
And phase theta _M of the motor M calculated by 10, the steering torque τ and the handle, which is calculated by the steering torque calculation unit 330, and the vehicle speed V _n, which is calculated by the vehicle speed calculating section 320,
A value of a desired torque (command torque T) to be output is calculated based on the steering angle θ _{H and the} like calculated by the steering angle calculation unit 500. For example, the angle detection unit 310 uses the resolver R
Based on the output value n of / D, the rotation angle (phase) θ _M of the motor _M is calculated by the following equation (1).

Equation 1 θ _M = 2πn / 64 (n is an integer; 0 ≦ n <63) (1)

The command torque calculation section 200 mainly, assist torque calculation unit 210 for calculating the assist torque T _A
If, inertia compensation torque calculation unit 220 for calculating the inertia compensation torque T _K, the damper torque calculation unit 230 for calculating a damper torque T _D, the steering wheel return torque calculation unit 240 or the like calculates the steering wheel return torque T _R It is configured. Command torque calculator 200 calculates command torque T according to the following equation (2).

T = T _A + T _K + T _D + T _R (2)

FIG. 3 shows the neutral position learning section 241 of this embodiment.
Handle return torque calculation unit 240 before the completion of the first learning
FIG. 2 is a block diagram showing a functional configuration of the first embodiment. Neutral position learning unit 2
41 is the neutral position of the steering wheel (zero point of the steering angle) after the ignition key of the vehicle is switched to the ON state.
Θ Start learning _O. This learning is based on the vehicle speed V _n ,
When the steering torque τ exerted on the steering wheel by the driver satisfies a predetermined “vehicle straight-running condition”, the steering angle θ _H of the steering wheel is sampled, and is executed by a predetermined statistical operation based on the sample data. Therefore, as long as the number of samples does not reach the predetermined number, the steering wheel neutral position Θ
_O is never output from the neutral position learning unit 241.

The steering neutral position Θ _O which is the learning result
Is output at least once (first).
Steering wheel return torque T _R (command value) is determined based on the steering speed omega _H. The steering speed ω _H is equal to the steering torque τ
Based on motor rotation angle theta _M and the steering speed estimating section 242
Is calculated by The steering speed ω _H is equal to the steering torque τ
A rotation angular velocity of the torsion bar of the torque sensor 15 is calculated from the amount of change is calculated as the sum of the rotation angular velocity of the pinion shaft 13, which is calculated from the variation amount of the motor rotation angle theta _M.

Furthermore, thereafter, until at least the first cycle is completed in the neutral position learning wheel return torque T _R are determined in accordance with the following equation (3) to (5).

T _R = G1 · T _R ″ (3)

G1 = g1 (V _n ) (4)

T _R ″ = f1 (ω _H ) (5) Here, the functions g1 and f1 are defined in the form of, for example, the data map 243 and the data map 244 in FIG. is there.

[0034] Thus, obtained until at least the first cycle is completed in the neutral position learning, be determined based on the command value T _R of the steering wheel return torque to the steering speed omega _H, conventional large taken forced to The desired steering wheel return torque can be output from the motor M even in the control dead zone where there is no control.

Further, since the completion of at least the first one of the neutral position learning, more preferably, from learned handle neutral position theta _O of precision is sufficiently improved by the neutral position learning unit 241, then Is difficult to rotate the handle due to the self-aligning torque (ie,
It is difficult to rotate the motor M due to the road surface reaction force.) The steering wheel return angle based on the steering angle (the steering wheel rotation angle) θ _H is capable of exhibiting sufficient steering wheel return performance even on a low friction road surface such as a frozen road. carry out. According to the control based on the steering angle θ _H , the steering wheel return performance on a low friction road, which is difficult to compensate by the control based on the steering speed ω _H , can be sufficiently secured, and at the same time, the steering wheel returns excessively. The so-called overshoot phenomenon can be avoided.

That is, more specifically, such a steering angle θ
The control of the steering wheel return torque based on the _H
This can be realized by the handle return torque calculation unit 240 of FIG. FIG. 4 illustrates a neutral position learning unit 241 according to the present embodiment.
FIG. 7 is a block diagram showing a functional configuration of a steering wheel return torque calculation unit 240 after learning of the steering wheel is completed.

As shown in FIG. 4, the steering angle θ _H of the steering wheel
After the number of samples reaches a predetermined number, the handle neutral position theta _O is output from the neutral position learning unit 241. Then, steering wheel return torque T _R can be determined according to the following equation (6) to (9).

T _R = G 1 · G 2 · T _R '(6)

T _R ′ = f2 (Θ) (7)

８ = θ _H −Θ _O (8)

G2 = g2 (τ) (when Θ> 0), G2 = g2 (−τ) (when Θ <0) (9) Here, the functions f2 and g2 are, for example, as shown in FIG. Are defined in the form of a data map 245 and a data map 246 (when Θ> 0).

Here, the function g2 realizes the steering wheel return torque limiting means of the present invention. When the driver slowly (or weakly) performs the steering wheel return operation or when the driver is in a released state, the gain g2 is set to the function g2. It is configured to be 1. For this reason, the steering state determining means and the steering wheel return current limiting means (FIG. 4) of the present invention, which can be realized using the method of FIG. 4, for example, using the steering determination map 246 of FIG.
Then, the case of “Θ> 0” is exemplified. According to), from a state in which the handle is turned off during low-speed travel, when the driver performs slowly return steering (or weak), and since the steering wheel return torque T _R is effective when the hands-off state A steering feeling substantially similar to that of a hydraulic power steering device can be realized.

FIG. 5B illustrates a modified example (steering determination map 246b) of the steering determination map 246 of the steering wheel return torque calculator 240 after the learning of this embodiment is completed. This graph shows the form of a function g3 which is a modification of the function g2 when “Θ> 0”. Thus, the absolute value of tau | tau | when is large, the time of returning the handle, as the sum of the assist torque T _A and steering wheel return torque T _R is not too large, adjusting the size of the G2 A method is also conceivable. According to such a method, it is possible to more reliably prevent a phenomenon (overshoot) that the motor M applies too much torque to the steering system (steering mechanism) when returning the steering wheel.

Such an adjustment is performed by the assist torque calculation section 210 (FIG. 1) for calculating the assist torque T _A.
May be implemented on the side of. For example, the steering angle の in which the neutral position after learning is adjusted on the side of the assist torque calculation unit 210 is set.
According to a method such as inputting such a method, such adjustment can be performed substantially in the same manner as the above method.

FIG. 6 is a flowchart of a control program 500a for realizing the steering angle calculation section 500 (steering angle estimation means) in FIG. In the control program 500a, first, in step 520, the rotation angle (phase) θ _M of the motor M calculated by the angle detection unit 310 (FIG. 1) according to the equation (1) is used to calculate the phase θ _M change amount D from the previous control cycle (= θ _M -θ0) Request. However, where, .theta.0 is the value of the phase theta _M in the previous control cycle.

Next, at step 530, the magnitude of the change amount D is determined.
Otherwise, the process moves to step 550. In step 540, the value of the variation D is reduced by 2π (during underflow). In step 550, the magnitude of the change amount D is determined. If it is smaller than -π, the process proceeds to step 560; otherwise, the process proceeds to step 570. Step 56
At 0, the value of the variation D is increased by 2π (at the time of overflow).

[0043] At step 570, the value of the motor rotational angle theta _m, based on the change amount D obtained in the above process, i.e.,
It is calculated according to the following equation (10).

[Expression 10] θ _m = θ _m + D (10)

In step 580, the rotation angle θ _H of the steering wheel (pinion shaft 13) is calculated according to the following equation (11). Here, R is a reduction ratio between the motor and the steering wheel (gear ratio between the two gears (17) in FIG. 1).

Θ _H = θ _m / R (11) In step 590, the motor M (of the current control cycle) is
Storing the phase theta _M in the save area .theta.0.

Such an overflow / underflow determination is made by determining the maximum value ω _Hmax of the rotational angular velocity of the steering wheel (ie, the steering speed ω _H ) and the control execution period t0 at which the program 500a is periodically executed as follows. The condition is satisfied when (12) is satisfied.

Π> R · ω _Hmax · t0 (12)

Although the maximum value ω _Hmax of the steering speed ω _H slightly depends on the configuration of the steering mechanism, it is usually the maximum value of the steering speed that can be operated by a human.
[Rad / sec] is normal. Therefore, equation (1)
As can be seen from 2), by configuring the system such that the value of the product R · t0 of the reduction ratio R and the control execution period t0 is lower than π / _ωHmax , the above-described steering angle estimation of the present invention is performed. It is possible to realize the means, that is, to effectively operate the program 500a. More specifically, for example, R
= 5, t0 = 1/100 [sec],
Such a condition can be reliably satisfied.

The output value n (6-bit information: 0 to 63) of the resolver R / D (rotation angle sensor) expresses only the phase of the motor M (0 ≦ θ _M <2π). However, the information amount of the output value n is, for example, 3 bits in the upper bit side.
If extended approximately 5 bits, the motor rotation angle theta _m of the calculated at program 500a, easily, i.e. to omit the determination process of overflow, etc., straightforward to determine that more hardware (resolver R / D) Is also possible. The above-described second and fourth means of the present invention may be implemented based on such a hardware configuration. That is, the above-described second and fourth means of the present invention also include the embodiment having such a hardware configuration, and even in such a case, the operation and effect of the present invention can be obtained. It is.

Further, the above-described embodiment is capable of simultaneously executing the first means, the second means, and the third means of the present invention, respectively. The present invention is constituted by the sixth means.
Since the means, the second means, and the third means are independent inventions, each of these means can also be implemented individually. That is, each of the first means, the second means, and the third means of the present invention does not require any other means as an implementation condition.

Further, the above-mentioned predetermined “vehicle straight traveling condition” is as follows:
For example, it may be dynamically changed according to a learning history such as the number of times of learning or a learning result. For example, as the number of times of learning increases, the boundary value of the vehicle speed used to determine the “vehicle straight-running condition” is changed from a minimum of about 30 km / hr to a maximum of 50 km.
For example, a method of gradually increasing the value to about m / hr may be used. For example, according to such means, it is possible to shorten the time until the completion of the initial learning, and to simultaneously improve the learning accuracy according to the learning history and the like.

[Brief description of the drawings]

FIG. 1 is a hardware configuration diagram of an electric power steering apparatus 100 according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a logical configuration of a motor control device 110 that drives and controls a motor M of the electric power steering device 100 according to the embodiment of the present invention.

FIG. 3 is a diagram illustrating a neutral position learning unit 241 according to an embodiment of the present invention.
FIG. 7 is a block diagram showing a functional configuration of a steering wheel return torque calculation unit 240 before learning is completed.

FIG. 4 is a diagram illustrating a neutral position learning unit 241 according to an embodiment of the present invention.
FIG. 4 is a block diagram showing a functional configuration of a steering wheel return torque calculation unit 240 after learning of the steering wheel is completed.

FIGS. 5A and 5B are graphs exemplifying a steering determination map 246 of the steering wheel return torque calculation unit 240 after learning is completed according to the embodiment of the present invention.

FIG. 6 is a flowchart of a control program 500a that implements a steering angle calculation unit (steering angle estimation unit) 500 according to the embodiment of the present invention.

FIG. 7 is a block diagram showing a functional configuration of a steering wheel return torque calculation unit having a neutral position learning function according to the related art.

[Explanation of symbols]

M… Motor R / D… Resolver (rotation angle sensor of motor M) n… Resolver output signal θ _M … Motor rotation angle (phase: 0 ≦ θ _M <2π) θ _m … Motor rotation angle θ _H … Handle rotation angle ω _H … Steering speed Θ _O … Steering wheel neutral position T _R … Steering wheel return torque (command value) T… Command torque τ… Steering torque V _n … Vehicle speed 10… Steering shaft 11… Steering wheel (handle) 100… Electric power steering Device 110: Motor control device 111: CPU 200: Command torque calculation unit 240: Handle return torque calculation unit 241: Neutral position learning unit 246: Steering determination map (corresponds to a steering state determination unit and a steering wheel return current limiting unit. In FIG. 4, , “Θ> 0”.) 500... Steering angle calculation unit (steering angle estimating means) 500a A control program for realizing steering angle calculating section (steering angle estimation means)

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) B62D 119: 00 B62D 119: 00 137: 00 137: 00 (72) Inventor Hirotsune Suzuki 1-chome Asahicho, Kariya City, Aichi Prefecture No. 1 Toyota Koki Co., Ltd. (72) Inventor Hiroshi Suzuki 1-1-1 Asahimachi, Kariya City, Aichi Pref. EA01 EB11 EC23 EC30 GG01 3D033 CA03 CA13 CA16 CA17 CA19 CA20 CA21 CA24

Claims (6)

[Claims] 1. An electric power steering apparatus comprising: a steering mechanism including a motor that applies torque to a steering shaft or a steering gear of a vehicle; and a control device that controls driving of the motor. Neutral position learning for learning the neutral position of the steering angle θ _H of the steering wheel according to a predetermined statistical operation when V _n and the steering torque τ exerted on the steering wheel by the driver satisfy a predetermined “vehicle straight traveling condition”. and means, based on the neutral position, on the basis of the steering angle theta _H, a first handle return control means for calculating the steering wheel return torque T _R, based on the rotational angular velocity omega _M of the motor, steering wheel return torque T and a second handle return control means for calculating _R, the neutral position learning by at least the neutral position learning means is completed once or Between the electric power steering apparatus characterized by determining the steering wheel return torque T _R by said second wheel return controlling means. 2. A steering mechanism comprising a brushless DC motor having a built-in rotation angle sensor for synchronization for applying torque to a steering shaft or a steering gear of a vehicle, and a control device for controlling the driving of the motor. An electric power steering apparatus comprising: a steering angle estimating unit that estimates a steering angle θ _H of a steering wheel based on an output signal of the rotation angle sensor. 3. An electric power steering apparatus comprising: a steering mechanism including a motor that applies torque to a steering shaft or a steering gear of a vehicle; and a control device that controls the driving of the motor. v, and the driver is steering torque τ exerted relative to the handle, given in satisfying "vehicle straight condition", a neutral position learning means for learning the neutral position of the steering angle theta _H of the handle in accordance with predetermined statistical operation If, based on the neutral position, on the basis of the steering angle theta _H, a handle return control means for determining a steering wheel return torque T _R, based on the steering torque tau, steering state determination for determining the steering state of the steering wheel Means, and the steering wheel return control means, in accordance with the steering state, performs an operation with respect to steering at the time of steering or turning operation. Shisutotoruku suppresses the steering wheel return torque T _R so as not to reduce, let go or return to the time of the operation handle, an electric power, characterized in that it comprises a steering wheel return torque limiting means to maintain or adjust the steering wheel return torque T _R Steering device. 4. A steering mechanism including a brushless DC motor having a built-in rotation angle sensor for synchronization, and a steering angle estimation means for estimating a steering angle θ _H of a steering wheel based on an output signal of the rotation angle sensor. The electric power steering apparatus according to claim 3, comprising: 5. When the vehicle speed V _n of the vehicle and the steering torque τ exerted on the steering wheel by the driver satisfy a predetermined “vehicle straight traveling condition”, the neutral position of the steering angle θ _H of the steering wheel is set to a predetermined value. a neutral position learning means for learning in accordance with statistical operation based on the said neutral position, on the basis of the steering angle theta _H, handle and first handle return control means for calculating a torque T _R back, the rotational angular velocity omega _M of the motor Second steering wheel return control means for calculating a steering wheel return torque TR based on the second steering wheel return torque T _R , at least until the learning of the neutral position by the neutral position learning means is completed once. the electric power steering apparatus according to any one of claims 2 to 4, characterized in that determining the steering wheel return torque T _R the control unit. 6. After the learning of the neutral position by the neutral position learning means is completed, the steering wheel return torque T _R
6. The electric power steering apparatus according to claim 1, wherein the first steering wheel return control means is determined.