JP5456648B2 - Electric power steering device - Google Patents

Description

  The present invention relates to an electric power steering device mounted on a vehicle, and more particularly to a technique for improving steering performance and stability at the time of collision avoidance.

  In recent automobiles, an electric power steering system (hereinafter referred to as EPS) that applies an assist torque by an electric motor is often used instead of the conventional hydraulic power steering apparatus. In the electric power steering device, there is no direct engine drive loss because an in-vehicle battery is used as the power source of the electric motor, and since the electric motor is started only at the steering assist, a decrease in driving fuel consumption can be suppressed, There is a feature that control by an ECU (electronic control unit) can be performed very easily.

  In EPS, the assist torque can be easily increased or decreased by controlling the current supplied to the electric motor. Therefore, the steering reaction torque is set according to the movement state quantity (yaw rate, lateral acceleration, vehicle speed) of the vehicle body. In general, correction for subtracting the steering reaction torque from the assist torque set by the steering torque is performed. However, when the steering reaction torque is uniformly set only by yaw rate or lateral acceleration, good running stability and steering feeling are always obtained when a disturbance occurs or when driving on a low μ road (such as a snowy road). I could not. Therefore, the present applicant sets a target steering angular velocity (an angular velocity at which the steering wheel returns to the neutral position) according to the running stability and vehicle speed estimated from the vehicle body behavior, and based on the difference between the target steering angular velocity and the actual steering angular velocity. A technique for setting the steering reaction torque has been proposed in the past (see Patent Document 1). According to this technology, for example, when the driving stability is low, the target steering angular speed can be increased to suppress the deflection of the vehicle body, and when the driving stability is high, the target steering angular speed can be decreased to improve the steering feeling. It becomes.

JP 2010-111158 A

  The technique of Patent Document 1 has a problem that it is difficult to ensure steering performance and stability during emergency steering because the target steering angular velocity is set only in accordance with traveling stability and vehicle speed. In recent automobiles, for example, a radar installed at the front of the vehicle body recognizes obstacles ahead, or recognizes that collision avoidance steering is performed by the driver based on the steering speed, and avoids collision. A collision avoidance support device that performs drive control of a braking device has appeared. However, in the EPS of Patent Document 1, the control parameter of the collision avoidance support device is not used for setting the target steering angular velocity, so that the steering reaction force is too large, making it difficult to perform sudden steering for collision avoidance, and vice versa. However, the steering reaction force is too small, which causes excessive steering by a driver who panics.

  The present invention has been made in view of such a background, and an object of the present invention is to provide an electric power steering device that realizes improvement in steering performance and stability at the time of collision avoidance and the like.

In the first aspect of the present invention, an electric steering assist motor (9) for applying an assist force to the steering mechanism, a steering angle detection means (11) for detecting the steering angle of the steering wheel (2), and the steering wheel The actual steering angular velocity detecting means (43) for detecting the actual steering angular velocity as the actual steering angular velocity, the actual steering torque detecting means (12) for detecting the actual steering torque applied to the steering wheel from the driver, and the steering angle detecting means Based on the detection result, target steering angular velocity setting means (40 to 42) for setting a target steering angular velocity of the steering wheel, and a steering angular velocity difference calculation that calculates a difference between the target steering angular velocity and the actual steering angular velocity as a steering angular velocity difference. Means (44, 45, 50) and target assist torque setting means for setting a target assist torque based on the actual steering torque 35), steering reaction force torque setting means (34) for setting a steering reaction force torque based on the difference in steering angular velocity, and assist torque correction means (35) for correcting the target assist torque by the steering reaction force torque. , An electric power steering apparatus provided with an urgent degree determining means (25) for determining an urgent degree of steering, wherein the target steering angular velocity setting means is determined to have a high degree of urgency by the urgency degree determining means The target steering angular velocity is changed so that the steering wheel can be steered more easily in the direction in which the steering wheel returns to the neutral position than when the urgency determination means determines that the urgency is low.

The second aspect of the present invention further includes a collision possibility determination unit that determines a collision possibility with an obstacle around the vehicle body, wherein the target steering angular velocity setting unit has an urgency level determined by the urgency level determination unit. When it is determined that the vehicle is high and the collision possibility determination means determines that the collision possibility is low, the target steering angular velocity is changed so that the steering wheel can be easily steered in the direction of returning to the neutral position.

In the third aspect of the present invention, an electric steering assist motor (9) for applying an assist force to the steering mechanism, a steering angle detecting means (11) for detecting the steering angle of the steering wheel (2), An actual steering angular velocity detection means (43) for detecting the steering angular velocity of the steering wheel as an actual steering angular velocity, an actual steering torque detection means (12) for detecting an actual steering torque applied to the steering wheel by the driver, and the steering angle Based on the detection result of the detection means, target steering angular speed setting means (40 to 42) for setting a target steering angular speed of the steering wheel, and a steering angular speed for calculating a difference between the target steering angular speed and the actual steering angular speed as a steering angular speed difference. The target assist torque setting for setting the target assist torque based on the difference calculating means (44, 45, 50) and the actual steering torque. Means (35), steering reaction force torque setting means (34) for setting a steering reaction force torque based on the steering angular velocity difference, and assist torque correction means (35) for correcting the target assist torque by the steering reaction force torque. ) And an urgency level determination means (25) for determining the urgency level of steering, wherein the target steering angular velocity setting means is determined to have a high urgency level by the urgency level determination means. In this case, the target steering angular velocity is changed so that the steering wheel can be steered in a direction away from the neutral position as compared with the case where the emergency level is determined to be low by the emergency level determination unit.

According to a fourth aspect of the present invention, an electric steering assist motor (9) for applying an assist force to the steering mechanism, a steering angle detecting means (11) for detecting the steering angle of the steering wheel (2), An actual steering angular velocity detection means (43) for detecting the steering angular velocity of the steering wheel as an actual steering angular velocity, an actual steering torque detection means (12) for detecting an actual steering torque applied to the steering wheel by the driver, and the steering angle Based on the detection result of the detection means, target steering angular speed setting means (40 to 42) for setting a target steering angular speed of the steering wheel, and a steering angular speed for calculating a difference between the target steering angular speed and the actual steering angular speed as a steering angular speed difference. The target assist torque setting for setting the target assist torque based on the difference calculating means (44, 45, 50) and the actual steering torque. Means (35), steering reaction force torque setting means (34) for setting a steering reaction force torque based on the steering angular velocity difference, and assist torque correction means (35) for correcting the target assist torque by the steering reaction force torque. ), And an urgency determination means (25) for determining the urgency of steering and a collision possibility determination means for determining the possibility of collision with an obstacle around the vehicle body, the target The steering angular velocity setting means changes the target steering angular velocity when the emergency degree determination means determines that the emergency degree is high, and changes the target steering angular speed when the emergency degree determination means determines that the emergency degree is low. When the possibility determination means determines that the possibility of a collision is high, the target is set so that the steering wheel can be steered in a direction away from the neutral position To change the steering angular velocity.

  According to the present invention, for example, when the degree of urgency is relatively low (for example, when there is a relatively long distance from the preceding vehicle), the resistance to steering wheel increase increases, resulting in the driver's sudden steering. While anxious vehicle body behavior is suppressed, when the degree of urgency is high (for example, when there is a high possibility of a collision with a preceding vehicle), it is easy to increase the steering wheel and to avoid a collision.

It is a schematic structure figure of the electric power steering device concerning the embodiment concerning a 1st embodiment. It is a block diagram which shows schematic structure of EPS-ECU which concerns on 1st Embodiment. It is a block diagram which shows schematic structure of the steering reaction force setting part which concerns on 1st Embodiment. It is a flowchart which shows the procedure of the steering reaction force torque setting process which concerns on 1st Embodiment. It is a normal time target steering angular velocity map concerning a 1st embodiment. 3 is an emergency target steering angular velocity map according to the first embodiment. It is a block diagram which shows schematic structure of the steering reaction force setting part which concerns on 2nd Embodiment. It is an emergency target steering angular velocity map concerning a 2nd embodiment. It is a block diagram which shows schematic structure of the steering reaction force setting part which concerns on 3rd Embodiment. It is a flowchart which shows the procedure of the steering reaction force torque setting process which concerns on 3rd Embodiment.

  Hereinafter, several embodiments in which the present invention is applied to an electric power steering apparatus for a passenger car will be described in detail with reference to the drawings.

[First Embodiment]
<< Configuration of First Embodiment >>
As shown in FIG. 1, an electric power steering apparatus 1 includes a rackion having a pinion 4 connected to a steering wheel 2 via a steering shaft 3, and a rack 5 that meshes with the pinion 4 and reciprocates in the vehicle width direction. Equipped with an and pinion mechanism. Both ends of the rack 5 are connected to the knuckle arms 8 on the left and right front wheels 7 via the tie rods 6, and the left and right front wheels 7 are steered according to the steering of the steering wheel 2. A steering assist mechanism 9 including a motor, a gear, and the like is mounted on the rack 5 coaxially. The assisting force generated by the steering assist mechanism 9 reduces the driver's steering force.

  The steering shaft 3 is provided with a steering angle sensor 11 for detecting the steering angle θ of the steering wheel 2 at the top, and a steering torque sensor 12 for detecting steering torque is provided in the vicinity of the pinion 4. A vehicle speed sensor 13 for detecting the vehicle speed V and a yaw rate sensor 14 for detecting the actual yaw rate of the vehicle body are provided at appropriate positions of the vehicle body. The steering assist mechanism 9 is provided with a resolver 15 that detects a motor rotation angle.

  Output signals from the sensors 11 to 15 are input to a steering control device (EPS-ECU) 21. The EPS-ECU 21 is a device that comprehensively controls the electric power steering device 1 and includes a microcomputer, a ROM, a RAM, a peripheral circuit, an input / output interface, various drivers, and the like. A target control amount (target current) is determined based on the output signal of the support device 25 and is output to the drive circuit 22 of the steering assist mechanism 9. The drive circuit 22 is configured by an FET bridge or the like, and supplies drive current to the steering assist mechanism 9 based on the target control amount determined by the EPS-ECU 21, thereby assisting the rack 5 from the steering assist mechanism 9. Force is controlled.

<EPS-ECU>
As shown in FIG. 2, the EPS-ECU 21 includes an assist base value setting unit 31, an angular velocity calculation unit 32, a damper compensation unit 33, a steering reaction force setting unit 34, an assist torque setting unit 35, and a target current. A setting unit 36 is internally provided.

  The assist base value setting unit 31 sets the assist torque base value Tab based on output signals from the steering angle sensor 11, the steering torque sensor 12, and the vehicle speed sensor 13. The angular velocity calculation unit 32 calculates the angular velocity of the steering assist mechanism 9 based on the output signal of the resolver 15 and outputs the angular velocity signal to the damper compensation unit 33. The damper compensation unit 33 sets an attenuation correction value for the steering assist mechanism 9 based on output signals from the steering angle sensor 11, the yaw rate sensor 14, and the angular velocity calculation unit 32. The assist torque setting unit 35 sets a target assist torque Tat based on the assist torque base value Tab, the attenuation correction value, and the steering reaction force torque Tr. The target current setting unit 36 sets a target current It based on the assist torque target value input from the assist torque setting unit 35, and outputs this to the drive circuit 22.

<Collision avoidance support device>
The collision avoidance assisting device 25 can collide with an obstacle based on the distance to a front obstacle detected by a radar (not shown) installed at the front of the vehicle body and the vehicle speed V input from the vehicle speed sensor 13. (I.e., urgency), the warning display in the instrument panel is turned on and the warning sound generator is blown in response to the urgency. In addition, an emergency flag Femg is output to the steering reaction force setting unit 34 of the EPS-ECU 21.

<Steering reaction force setting unit>
As shown in FIG. 3, the steering reaction force setting unit 34 sets first and second target steering angular velocities that respectively set a normal target steering angular velocity KTω and an emergency target steering angular velocity KMω based on the vehicle speed V and the steering angle θ. The calculation units 40 and 41, the steering angular velocity calculation unit 43 that calculates the actual steering angular velocity ω by time differentiation of the steering angle θ, and the difference between the normal target steering angular velocity KTω and the actual steering angular velocity ω is the normal steering angular velocity difference DTω. The first adder 44 calculated as follows, the second adder 45 that calculates the difference between the emergency target steering angular velocity KMω and the actual steering angular velocity ω as the emergency steering angular velocity difference DMω, and the emergency from the collision avoidance support device 25 Based on the selection result of the angular velocity difference selection unit 46 and the angular velocity difference selection unit 46 that selects either the normal steering angular velocity difference DTω or the emergency steering angular velocity difference DMω as the steering angular velocity difference Dω based on the flag Femg. The reaction force base value setting unit 47 for setting the steering reaction force torque base value Trb, and the steering reaction force by limiting the upper limit value and the lower limit value (maximum values on the outgoing side and the return side) of the steering reaction force torque base value Trb. A steering reaction force limiter 48 that outputs torque Tr is provided.

<< Operation of First Embodiment >>
When the automobile starts traveling, the EPS-ECU 21 repeatedly executes steering assist control at a predetermined processing interval (for example, 10 ms). When the steering assist control is started, the EPS-ECU 21 first sets the assist torque base value Tab by the assist base value setting unit 31, while the damping compensation value and the steering reaction force torque by the damper compensation unit 33 and the steering reaction force setting unit 34. Tr is set. Next, the EPS-ECU 21 calculates the target assist torque Tat by correcting the assist torque base value Tab with the attenuation correction value and the steering reaction torque Tr, and sets and drives the target current It based on the assist torque target value. Output to the circuit 22. As a result, an assist force is applied from the steering assist mechanism 9 to the rack 5 to reduce the driver's steering burden.

<Setting of steering reaction torque>
The EPS-ECU 21 executes a steering reaction torque setting process whose procedure is shown in the flowchart of FIG. 4 in parallel with the steering assist control described above.
When the steering reaction torque setting process is started, the EPS-ECU 21 searches the normal target steering angular velocity KTω from the normal target steering angular velocity map of FIG. 5 in step S1 of FIG. 4 based on the vehicle speed V and the steering angle θ. In step S2, the emergency target steering angular velocity KMω is retrieved / set from the emergency target steering angular velocity map of FIG. Next, the EPS-ECU 21 calculates the actual steering angular velocity ω by time differentiating the steering angle θ in step S3, and then subtracts the normal target steering angular velocity KTω from the actual steering angular velocity ω in step S4. The angular speed difference DTω is set, and the emergency steering angular speed difference DMω is set by subtracting the emergency target steering angular speed KMω from the actual steering angular speed ω in step S5.

  Next, the EPS-ECU 21 determines whether or not the emergency flag Femg is input from the collision avoidance support device 25 in step S6 (whether or not Femg = 1). In S7, the steering reaction force torque base value Trb is calculated / set by multiplying the normal steering angular speed difference DTω by a predetermined conversion coefficient K. If Yes, the emergency steering angular speed difference DMω is converted into the predetermined conversion coefficient K in step S8. To calculate / set the steering reaction torque base value Trb.

(Normal target steering angular velocity map)
As can be seen from FIG. 5, the normal target steering angular velocity KTω is set to a negative value having a relatively small absolute value when the steering angle θ is positive (right steering direction) in the first target steering angular velocity calculation unit 40. When the steering angle θ is negative (left steering direction), a relatively small positive value is set.

(Emergency target steering angular velocity map)
On the other hand, as can be seen from FIG. 6, the emergency target steering angular velocity KMω is absolute in the second target steering angular velocity calculation unit 41 as compared with the normal target steering angular velocity map when the steering angle θ is positive (right steering direction). When the steering angle θ is negative (left steering direction), it is set to a large positive value as compared with the normal target steering angular velocity map.

  Next, the EPS-ECU 21 determines whether or not the steering reaction torque base value Trb is larger than the first threshold value Trm1 (upper limit value in the left direction) in step S9. If this determination is Yes, in step S10. The steering reaction force torque setting process is terminated using the first threshold value Trm1 as the steering reaction force torque Tr.

  On the other hand, if the determination in step S9 is No, the EPS-ECU 21 determines in step S11 whether or not the steering reaction torque base value Trb is smaller than the second threshold value Trm2 (the upper limit value in the right direction). If this determination is Yes, the steering reaction force torque setting process is terminated with the second threshold value Trm2 as the steering reaction force torque Tr in step S12. In the present embodiment, the first threshold value Trm1 and the second threshold value Trm2 are set to values having the same absolute value and different signs (positive / negative).

  If the determinations in steps S9 and S11 are both No, the EPS-ECU 21 ends the steering reaction torque setting process using the steering reaction torque base value Trb as the steering reaction torque Tr in step S13.

  In the present embodiment, by adopting the above-described configuration, when the degree of urgency is high (when the collision avoidance support device 25 determines that there is a high possibility of a rear-end collision or the like), resistance to increase of the steering wheel 2 increases. By doing so, the uneasy body behavior due to the driver's sudden steering is suppressed.

[Second Embodiment]
The second embodiment has the same configuration as that of the first embodiment described above, but the configuration of the steering reaction force setting unit 34 and the third target steering angular velocity calculation unit 42 (emergency target steering angular velocity map) are different. ing. That is, as shown in FIGS. 7 and 8, in the emergency target steering angular velocity map in the present embodiment, the emergency target steering angular velocity KMω is the normal target steering angular velocity when the steering angle θ is positive (right steering direction). When the steering angle θ is negative (left steering direction), the absolute value is set to a smaller positive value than the normal target steering angular velocity map. Therefore, the emergency steering angular velocity difference DMω (that is, the steering reaction force torque base value Trb in the normal state) is relatively large in the direction in which the steering wheel 2 is away from the neutral position (that is, the direction in which the steering wheel 2 is increased). Becomes relatively small in the direction approaching the neutral position (that is, the direction of switching back).

  In the present embodiment, by adopting the configuration described above, contrary to the first embodiment, when the degree of urgency is high (when the collision avoidance support device 25 determines that there is a high possibility of a rear-end collision), the steering It becomes easy to avoid a collision with an obstacle ahead because the wheel 2 is easily increased.

[Third Embodiment]
The third embodiment has substantially the same configuration as the first embodiment described above, but is different from the configuration of the steering reaction force setting unit 34. That is, as shown in FIG. 9, the steering reaction force setting unit 34 of the present embodiment includes the first target steering angular velocity calculation unit 40 that sets the normal target steering angular velocity KTω based on the vehicle speed V and the steering angle θ. , Second and third target steering angular velocity calculation units 41 and 42 for setting the emergency target steering angular velocity KMω, respectively. Here, the second target steering angular velocity calculating unit 41 is the same as the second target steering angular velocity calculating unit 41 of the first embodiment, and the third target steering angular velocity calculating unit 42 is the third target steering angular velocity of the second embodiment. This is the same as the angular velocity calculation unit 42.

<< Operation of Third Embodiment >>
<Setting of steering reaction torque>
The EPS-ECU 21 executes a steering reaction torque setting process whose procedure is shown in the flowchart of FIG. 10 in parallel with the steering assist control described above.
When the steering reaction torque setting process is started, the EPS-ECU 21 searches the normal target steering angular velocity KTω from the normal target steering angular velocity map of FIG. 5 in step S21 of FIG. 10 based on the vehicle speed V and the steering angle θ. In step S22, the first emergency target steering angular velocity KMω1 is retrieved / set from the first emergency target steering angular velocity map of FIG. 6, and in step S23, the first emergency target steering angular velocity map of FIG. 2 Search / set the emergency target steering angular velocity KMω2.

  Next, the EPS-ECU 21 calculates the actual steering angular velocity ω by time differentiating the steering angle θ in step S24, and then subtracts the normal target steering angular velocity KTω from the actual steering angular velocity ω in step S25. An angular velocity difference DTω is set, a first emergency steering angular velocity difference DMω1 is set by subtracting the first emergency target steering angular velocity KMω1 from the actual steering angular velocity ω in step S26, and a second emergency is calculated from the actual steering angular velocity ω in step S27. The second emergency steering angular velocity difference DMω2 is set by subtracting the hour target steering angular velocity KMω2.

  Next, the EPS-ECU 21 determines whether or not the middle emergency flag Femgm is input from the collision avoidance support device 25 in Step S28 (whether or not Femgm = 1). If this determination is Yes. In step S29, the second steering reaction force torque base value Trb2 is calculated / set by multiplying the second emergency steering angular velocity difference DMω2 by a predetermined conversion coefficient K. Here, the middle emergency flag Fegmm is a collision avoidance support when the distance to the obstacle (the vehicle ahead, etc.) is relatively small (for example, 7 m) and the vehicle speed V is relatively high (for example, 80 km / h). It is output from the device 25 to the angular velocity difference selection unit 46.

  If the determination in step S28 is No, the EPS-ECU 21 determines whether or not the high emergency flag Femgh is input from the collision avoidance assistance device 25 in step S30 (whether or not Feggh = 1). If this determination is Yes, the first steering reaction force torque base value Trb1 is calculated / set by multiplying the first emergency steering angular velocity difference DMω1 by the conversion coefficient K in step S31. Here, the high-emergency flag Femgh is a collision avoidance assistance device when the distance from an obstacle (such as a preceding vehicle) is very small (for example, 3 m) and the vehicle speed V is relatively high (for example, 80 km / h). 25 to the angular velocity difference selector 46.

  If the determination in step S30 is also No, the EPS-ECU 21 calculates / sets the steering reaction torque base value Trb by multiplying the normal steering angular velocity difference DTω by the conversion coefficient K in step S32.

  Next, the EPS-ECU 21 determines in step S33 whether or not the steering reaction torque base value Trb is larger than the first threshold value Trm1 (upper limit value in the left direction). If this determination is Yes, in step S34. The steering reaction force torque setting process is terminated using the first threshold value Trm1 as the steering reaction force torque Tr.

  On the other hand, if the determination in step S33 is No, the EPS-ECU 21 determines in step S35 whether or not the steering reaction torque base value Trb is smaller than the second threshold value Trm2 (the upper limit value in the right direction). If this determination is Yes, the steering reaction force torque setting process is terminated in step S36 with the second threshold value Trm2 as the steering reaction force torque Tr.

  If both the determinations in steps S33 and S35 are No, the EPS-ECU 21 ends the steering reaction force torque setting process using the steering reaction force torque base value Trb as the steering reaction force torque Tr in step S37.

  In the present embodiment, by adopting the above-described configuration, when the degree of urgency is relatively low (for example, when there is a relatively long distance from the preceding vehicle), resistance to additional steering wheel 2 increases. While the uneasy vehicle body behavior due to the driver's sudden steering is suppressed, the steering wheel 2 can be easily increased when the degree of emergency is high (for example, when there is a high possibility of a collision with a preceding vehicle). It is easier to avoid collisions.

  Although description of specific embodiment is finished above, the aspect of the present invention is not limited to the above embodiment. For example, in the above-described embodiment, the present invention is applied to EPS using a brushless motor as an assist motor of the steering assist mechanism, and the angular velocity detection unit detects the angular velocity of the assist motor based on the output signal of the resolver. The invention is naturally applicable to EPS using a brush motor as an assist motor. In that case, the angular velocity of the assist motor may be detected by time-differentiating the detected value of the steering angle sensor. In the above embodiment, the steering reaction torque base value is set based on the urgency flag from the collision avoidance assistance device. However, the collision avoidance steering is performed according to the steering angular velocity of the steering wheel (that is, by the driver). The steering reaction torque base value may be set (depending on whether or not) is performed. In addition, the specific configuration of the electric power steering device and the EPS-ECU, the specific procedure of the control, and the like can be changed as appropriate without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Electric power steering apparatus 2 Steering wheel 5 Rack 7 Left and right front wheel 9 Steering assist mechanism (steering assist motor)
11 Steering angle sensor (steering angle detection means)
12 Steering torque sensor (actual steering torque detection means)
13 Vehicle speed sensor 21 EPS-ECU
25 Collision avoidance support device (emergency determination means)
34 Steering reaction force setting section (steering reaction force torque setting means)
35 Assist torque setting unit (target assist torque setting means)
40 First target steering angular velocity calculation unit (target steering angular velocity setting means)
41 Second target steering angular velocity calculation unit (target steering angular velocity setting means 42) Third target steering angular velocity calculation unit (target steering angular velocity setting means)
43 Steering angular velocity calculation unit (actual steering angular velocity detection means)
46 Angular velocity difference selector

Claims (4)

An electric steering assist motor for applying assist force to the steering mechanism;
Steering angle detection means for detecting the steering angle of the steering wheel;
And the actual steering angular velocity detecting means for detecting a steering angular velocity of the steering wheel as an actual steering angular speed,
And the actual steering torque detection means for detecting an actual steering torque applied to the steering wheel from the driver,
Based on the detection result of the steering angle detecting means, a target steering angular velocity setting means for setting a target steering angular velocity of the steering wheel,
Steering angular velocity difference calculating means for calculating a difference between the target steering angular velocity and the actual steering angular velocity as a steering angular velocity difference;
Target assist torque setting means for setting a target assist torque based on the actual steering torque;
Steering reaction force torque setting means for setting a steering reaction force torque based on the steering angular velocity difference;
Assist torque correction means for correcting the target assist torque by the steering reaction torque;
An electric power steering apparatus comprising an urgent level determining means for determining an urgent level of steering,
In the target steering angular velocity setting means, the steering wheel is set to a neutral position when the urgency determination means determines that the urgency is high compared to when the urgency determination means determines that the urgency is low. An electric power steering device , wherein the target steering angular velocity is changed so that steering in a returning direction is facilitated . A collision possibility judging means for judging a collision possibility with an obstacle around the vehicle body;
The target steering angular velocity setting means, wherein it is determined that there is a high urgency by emergency level determination means, and, if it is determined that there is a low possibility collision by the collision possibility determination means, returning the steering wheel to the neutral position The electric power steering apparatus according to claim 1, wherein the target steering angular velocity is changed so that steering becomes easy in a direction in which the vehicle is steered. An electric steering assist motor for applying assist force to the steering mechanism;
Steering angle detection means for detecting the steering angle of the steering wheel;
And the actual steering angular velocity detecting means for detecting a steering angular velocity of the steering wheel as an actual steering angular speed,
And the actual steering torque detection means for detecting an actual steering torque applied to the steering wheel from the driver,
Based on the detection result of the steering angle detecting means, a target steering angular velocity setting means for setting a target steering angular velocity of the steering wheel,
Steering angular velocity difference calculating means for calculating a difference between the target steering angular velocity and the actual steering angular velocity as a steering angular velocity difference;
Target assist torque setting means for setting a target assist torque based on the actual steering torque;
Steering reaction force torque setting means for setting a steering reaction force torque based on the steering angular velocity difference;
Assist torque correction means for correcting the target assist torque by the steering reaction torque;
An electric power steering apparatus comprising an urgent level determining means for determining an urgent level of steering,
The target steering angular velocity setting means determines that the steering wheel is moved from a neutral position when the urgency determination means determines that the urgency is high compared to when the urgency determination means determines that the urgency is low. An electric power steering device , wherein the target steering angular velocity is changed so that steering in a direction away from the vehicle becomes easy . An electric steering assist motor for applying assist force to the steering mechanism;
Steering angle detection means for detecting the steering angle of the steering wheel;
And the actual steering angular velocity detecting means for detecting a steering angular velocity of the steering wheel as an actual steering angular speed,
And the actual steering torque detection means for detecting an actual steering torque applied to the steering wheel from the driver,
Based on the detection result of the steering angle detecting means, a target steering angular velocity setting means for setting a target steering angular velocity of the steering wheel,
Steering angular velocity difference calculating means for calculating a difference between the target steering angular velocity and the actual steering angular velocity as a steering angular velocity difference;
Target assist torque setting means for setting a target assist torque based on the actual steering torque;
Steering reaction force torque setting means for setting a steering reaction force torque based on the steering angular velocity difference;
Assist torque correction means for correcting the target assist torque by the steering reaction torque;
Urgency level determination means for determining the urgency level of steering;
An electric power steering apparatus comprising a collision possibility judging means for judging a collision possibility with an obstacle around the vehicle body ,
The target steering angular speed setting means changes the target steering angular speed when the emergency degree determination means determines that the urgency level is high, and when the urgency level determination means determines that the urgency level is low , If it is determined to be likely collision by said collision possibility determination means, the steering wheel is characterized Rukoto changing the target steering angular velocity so easily steered in a direction away from the neutral position, the electric power Steering device.

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