JP2005212643A - Power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power steering device capable of suppressing degradation of the steering feeling of a driver attributable to the change of the friction force of the entire steering mechanism. <P>SOLUTION: In S2, the standard control value in a case of the standard hysteresis width is determined, and in S3, the increase side typical value <Tδ> which is an average value of the output when the absolute value of the steering angle is increased in divided areas of the same steering angle and the decrease side typical value <Tδ> which is an average value of the output when the absolute value of the steering angle is decreased are acquired, and the absolute value of the difference between these typical values is acquired as the hysteresis width. In S4, the correction value is determined based on the difference between the standard hysteresis width and the actual hysteresis width. In S5, the sum of the standard control value and the correction value is determined as the control value. As a result, a driver can obtain the steering feeling similar to that in a case of the standard hysteresis width even when the hysteresis width is changed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to control of an auxiliary force in a power steering apparatus that gives an output obtained by adding an auxiliary force by an actuator to an input applied to a steering member to a steering wheel.

In Patent Document 1, a steering angle detection device that detects a steering angle of a steering wheel, a steering torque detection device that detects a steering torque as an input, a steering angle detected by the steering angle detection device, and a steering torque detection device. A power steering device is described that includes a hysteresis width acquisition device that acquires a Lissajous waveform from the detected steering torque and acquires a hysteresis width based on the Lissajous waveform.
JP 2002-308131 A

  An object of the present invention is to improve a hysteresis width acquisition device in a power steering device.

  A power steering device according to a first aspect of the present invention provides a power steering device that provides an output obtained by adding an auxiliary force by an actuator to an input applied to a steering member to a steering wheel, and (a) detects a steering amount of the steering member. (B) a steering related force acquisition device that acquires a steering related force that is one of the input and the output; and (c) at least a part of a steering allowable range of the steering member. When a steering amount detected by the steering amount detection device belongs to each of a plurality of divided areas determined by dividing into a plurality of regions, a representative value of the steering related force acquired by the steering related force acquisition device is acquired. This is a representative value of the steering related force acquired when the steering related force representative value acquisition means is provided and the absolute value of the steering amount increases in the same divided region of the plurality of divided regions. A hysteresis width acquisition device that acquires, as a hysteresis width, an absolute value of a difference between an addition-side representative value and a decrease-side representative value that is a representative value of the steering-related force acquired when the absolute value of the steering amount decreases; It is obtained by providing.

  In this power steering apparatus, when the hysteresis width in the relationship between the steering amount and the steering related force is acquired, at least a part of the steering allowable range of the steering member is divided into a plurality of regions, and each divided division is performed. A representative value of the steering related force in the region is acquired. The difference between the increase-side representative value that is the representative value of the steering-related force when the steering amount increases and the decrease-side representative value that is the representative value of the steering-related force when the steering amount decreases in the same divided region. The absolute value is acquired as the hysteresis width.

  The input and auxiliary force applied to the steering member may be expressed by force or torque. The sum of input and auxiliary force may be the sum of forces or the sum of torques. For example, when the steering member is a steering wheel, a steering torque applied to the steering wheel may be input, or a tangential force applied to the steering wheel may be input. Further, when the steering member is not rotationally steered, it can be expressed by a force applied to the steering member. The same applies to the auxiliary force. When the actuator is an electric motor, it can be expressed by the output torque of the electric motor, or by the left-right force applied to the rack shaft by the electric motor. When the actuator includes a hydraulic pressure control device and a horizontal force is applied to the rack shaft by the hydraulic pressure, it can be expressed by a force corresponding to the hydraulic pressure.

The divided area may be provided for the entire steering allowable range of the steering member or a part thereof. For example, since the frequency with which the steering member is steered to the limit of the steering allowable range is not so high, it is only necessary to provide a divided region for a range in which the steering frequency is high.
Each of the divided areas is represented by a steering amount that represents the divided area. The representative value of the steering amount representing the divided area can be, for example, a value that defines the upper end of the divided area, a value that defines the lower end, or the median value of the divided area.
In each of the cases where the absolute value of the steering amount increases and decreases, the representative value of the steering related force when the steering amount is in the same divided region is, for example, the average value of the steering related force or the steering related force Or an intermediate value between the maximum value and the minimum value. It is also possible to use a statistically processed value in consideration of the steering-related force distribution.
“The absolute value of the steering amount increases” means that the steering position of the steering member moves away from the neutral position, and the distance between the steering position and the neutral position increases. “The absolute value of the steering amount decreases” means that the steering position of the steering member approaches the neutral position and the distance between the steering position and the neutral position is reduced. The neutral position of the steering member is a position where the steering amount is 0, and can be, for example, the median value of the position range of the steering member that causes the vehicle to go straight. When the steering member is a steering wheel, it can be assumed that the steering wheel is in the neutral position when the steering angle, which is the steering amount, is 0 °.
Although the steering amount detection device can detect the steering amount itself from the neutral position of the steering member, such a configuration is not essential. Further, a physical quantity corresponding to the steering amount can be detected.

In the present power steering apparatus, the hysteresis width is acquired for the relationship between the steering amount and the input or the relationship between the steering amount and the output.
The driver steers the steering member while feeling the steering reaction force. The steering reaction force is the sum of the reaction force based on the force acting between the road surface and the tire of the steering wheel and the reaction force based on the friction force in the entire steering mechanism (mechanism from the steering member to the steering wheel).
The frictional force of the entire steering mechanism is not always the same for all vehicles due to manufacturing variations and the like. Moreover, it changes due to a temperature change or changes over time. If the frictional force of the entire steering mechanism changes, the reaction force based on it also changes.
The force acting between the road surface and the tire includes a force corresponding to the self-alignment torque, a frictional force between the road surface and the tire, and the like. The force acting between the road surface and the tire is determined by the state of wear of the tire, the state of the road surface (for example, it can be expressed by a friction coefficient, etc.), etc., and certain conditions such as in a region where the side slip angle is small Can be considered to change with a substantially constant gradient as the steering amount (corresponding to the steering angle of the steering wheel) changes. If the force acting between the road surface and the tire changes, the reaction force based on it also changes.

The steering reaction force increases as the absolute value of the steering amount increases, and decreases as the absolute value decreases. The frictional force of the entire steering mechanism varies depending on whether the absolute value of the steering amount increases or decreases. It can be considered that a hysteresis twice as large as the reaction force based on the above occurs.
If the tire wear state, road surface condition, etc. are almost the same, the vehicle running state and the steering member steering state are substantially the same, and the side slip angle is in a small region, the absolute value of the steering amount Since the change gradient of the steering reaction force with respect to the change of is constant, the hysteresis width is not necessarily acquired when the steering amount is 0, and can be acquired when the steering amount is other than 0.
Note that the “state where the traveling state and steering state of the vehicle are substantially the same” can be a state where the traveling state and steering state satisfy a predetermined condition, for example. If the distortion of the Lissajous waveform (closed curve) representing the relationship between the steering amount and the steering reaction force is small, and the running state and steering state satisfy the predetermined conditions, the increasing side representative value and the decreasing side representative value The absolute value of the difference from the value is adopted as the hysteresis width.

On the other hand, the output which is the sum of the input and the assisting force has a magnitude corresponding to the steering reaction force. The hysteresis width acquired for the relationship with the steering amount is twice as large as the reaction force based on the frictional force of the entire steering mechanism.
When the assist force is 0, the input is the same magnitude as the steering reaction force, and the hysteresis width acquired for the relationship between the input and the steering amount is twice the steering reaction force based on the friction force of the entire steering mechanism. It becomes the size of. In addition, when the assist force is a magnitude that boosts the input, the hysteresis width is not necessarily twice the steering reaction force corresponding to the friction force of the entire steering mechanism. The magnitude corresponds to twice the corresponding steering reaction force, and changes according to the change in the frictional force of the entire steering mechanism.
As described above, if the hysteresis width is acquired for the relationship between the steering amount and any one of the output and the input, a value corresponding to the frictional force of the entire steering mechanism can be acquired.
As described above, since the output has a magnitude corresponding to the steering reaction force, it is desirable to obtain the hysteresis width from the relationship between the output and the steering amount, which is a value obtained by adding the auxiliary force to the input.

In this power steering device, the representative value of the steering related force is acquired for each divided region, and the hysteresis width is acquired based on the respective representative value, so compared with the case based on the value of each steering related force, The hysteresis width can be acquired more accurately.
In addition, if the increase-side representative value and the decrease-side representative value are acquired for the same divided region, the hysteresis width can be acquired, and a Lissajous waveform (closed curve) representing the relationship between the steering-related force and the steering amount is completed. It will be possible to get before. Thus, when the hysteresis width is acquired before the above-described Lissajous waveform is created, an effect that the hysteresis width can be acquired earlier than in the case of the power steering device described in Patent Document 1 is also obtained.

Patentable invention

  In the following, the invention that is claimed to be claimable in the present application (hereinafter referred to as “claimable invention”. The claimable invention is at least the “present invention” to the invention described in the claims. Some aspects of the present invention, including subordinate concept inventions of the present invention, superordinate concepts of the present invention, or inventions of different concepts) will be illustrated and described. As with the claims, each aspect is divided into sections, each section is numbered, and is described in a form that cites the numbers of other sections as necessary. This is for the purpose of facilitating the understanding of the claimable invention, and is not intended to limit the combinations of the constituent elements constituting the claimable invention to those described in the following sections. In other words, the claimable invention should be construed in consideration of the description accompanying each section, the description of the embodiments, etc., and as long as the interpretation is followed, another aspect is added to the form of each section. In addition, an aspect in which constituent elements are deleted from the aspect of each item can be an aspect of the claimable invention.

  Of the following items, items (1) to (4) correspond to claims 1 to 4, items (8) to (10) correspond to claims 5 to 7, and item (13) This corresponds to claim 8.

(1) A power steering device that gives an output obtained by adding an auxiliary force by an actuator to an input applied to a steering member to a steering wheel,
A steering amount detection device for detecting a steering amount of the steering member;
A steering-related force acquisition device that acquires a steering-related force that is one of the input and the output;
When the steering amount detected by the steering amount detection device belongs to each of a plurality of divided areas determined by dividing at least a part of the steering allowable range of the steering member into a plurality, by the steering related force acquisition device It has steering related force representative value acquisition means for acquiring a representative value of the acquired steering related force, and is acquired when the absolute value of the steering amount increases in the same divided region of the plurality of divided regions. The absolute value of the difference between the increase-side representative value that is the representative value of the steering-related force and the decrease-side representative value that is the representative value of the steering-related force acquired when the absolute value of the steering amount decreases And a hysteresis width acquisition device that acquires as a power steering device.
(2) In the item (1), the hysteresis width acquisition device acquires the hysteresis width when at least one of a traveling state of a vehicle and a steering state of the steering member satisfies a predetermined condition. The power steering apparatus described.
As described above, the relationship between the steering amount and the steering-related force is affected by the traveling state of the vehicle and the steering state of the steering member.
For example, at the same steering amount, the steering reaction force is smaller when the vehicle speed is large than when the vehicle speed is small. Further, when the steering speed is high, the turning angle of the wheel becomes smaller due to the delay than when the steering speed is low, thereby changing the steering reaction force.
Thus, when the running state of the vehicle or the steering state of the steering member changes, the relationship between the steering amount and the steering-related force changes, and the Lissajous waveform is distorted. For this reason, it is desirable that the hysteresis width is acquired when the traveling state and the steering state satisfy predetermined conditions. Since this condition is a condition for accurately acquiring the hysteresis width, it can be referred to as a hysteresis width acquisition effective condition and a hysteresis width determination condition.
(3) The condition is that (a) the absolute value of the change speed of the steering amount is less than or equal to a set steering speed; The power steering device according to item (2), wherein the hysteresis width acquisition device acquires at least one of the hysteresis width when the condition is satisfied.
When the amount of decrease of the absolute value of the steering amount from the peak value is equal to or greater than the set amount, the direction of operation of the steering member has changed reliably (change from the state where the absolute value of the steering amount increases to the state where it decreases) ), And a state suitable for acquiring the decreasing representative value.
The set amount can be set to an amount that can be considered that the steering direction has been switched reliably. The set amount can be represented by the magnitude of the steering amount or the number of divided areas.
It should be noted that at least: (a ′) the absolute value of the change amount of the steering amount is larger than the set steering speed; and (b ′) the amount of decrease from the peak value of the absolute value of the steering amount is smaller than the set amount When one is satisfied, the hysteresis width can be prevented from being acquired.
(4) including a vehicle speed detection device for detecting a traveling speed of the vehicle, wherein the condition is (a) when the absolute value of the steering amount increases when the steering amount is in the same divided region, the vehicle speed detection The absolute value of the difference between the representative value of the vehicle speed detected by the device and the representative value of the vehicle speed when the absolute value of the steering amount decreases, and (b) the steering amount is divided into the same division When the absolute value of the steering amount increases and decreases, the minimum value of the vehicle speed is equal to or higher than a set speed, and (c) the steering amount is in the same divided region. In some cases, in each of the cases where the absolute value of the steering amount increases and decreases, at least one of the value obtained by subtracting the minimum value of the vehicle speed from the maximum value of the vehicle speed being equal to or less than a set value The hysteresis width acquisition device satisfies the condition. If it is, and acquires the hysteresis width (2) or (3) a power steering apparatus according to claim.
When the absolute value of the steering amount increases and decreases, when the variation in the vehicle speed is small when the steering amount is in the same divided region, when the minimum value of the vehicle speed is greater than or equal to the set speed, and when it increases When the difference between the vehicle speed and the vehicle speed is small, the hysteresis width can be obtained accurately.
The representative value of the vehicle speed in the same divided area can be the maximum value of the vehicle speed, the minimum value, the average value, the intermediate value between the maximum value and the minimum value, or the like.
(A ′) In the case where the steering amount is in the same divided region, the representative value of the vehicle speed detected by the vehicle speed detection device and the absolute value of the steering amount decrease when the absolute value of the steering amount increases. When the absolute value of the difference between the vehicle speed and the representative value is larger than a set value, and (b ′) when the steering amount is in the same divided region, the absolute value of the steering amount increases and decreases. In each case, the minimum value of the vehicle speed is equal to or higher than a set speed, and (c ′) when the steering amount is in the same divided region, the absolute value of the steering amount increases and decreases. In each case, when at least one of the value obtained by subtracting the minimum value of the vehicle speed from the maximum value of the vehicle speed being equal to or less than the set value is satisfied, the hysteresis width can be prevented from being acquired. .
(5) The steering related force representative value acquisition means acquires the steering related force representative value when at least one of a traveling state of a vehicle and a steering state of the steering member satisfies a predetermined condition. The power steering device according to any one of (1) to (4).
Since the hysteresis width is acquired as the absolute value of the difference between the increase-side representative value and the decrease-side representative value, the hysteresis width is not acquired when the steering-related force representative value is not acquired. When the steering amount is in the same divided region, in each of the cases where the steering amount increases and decreases, (i) the absolute value of the change rate of the steering amount is equal to or less than the set steering speed, and (ii ) At least one of the minimum value of the vehicle speed being equal to or higher than a set speed and (iii) the value obtained by subtracting the minimum value of the vehicle speed from the maximum value of the vehicle speed detected by the vehicle speed detecting device being equal to or less than the set value. The condition including the two is a condition based on the traveling state and the steering state in the same divided region, and can be considered as a condition for obtaining a representative value of the steering-related force.
In contrast, (i) the absolute value of the difference between the representative value of the vehicle speed when the absolute value of the steering amount increases and the representative value of the vehicle speed when the absolute value of the steering amount decreases is equal to or less than a set value. And (ii) the condition including at least one of the decrease amount from the peak value of the absolute value of the steering amount being a set amount or more can be considered as a condition for obtaining the hysteresis width. When the condition is not satisfied, the hysteresis width is not acquired even if the representative value of the steering related force is acquired.
(6) The steering related force representative value acquisition means includes at least one of a provisional value acquisition unit that provisionally acquires a steering related force representative value in the same divided area, and a vehicle running state and a steering member steering state. Including a representative value storage unit that determines a provisional value as a representative value and stores it in a storage unit in association with a steering amount that represents a divided region when a predetermined condition is satisfied. The power steering device according to any one of the above.
For example, when the steering related force is acquired, the representative value is provisionally determined, and when the traveling state or the steering state satisfies a predetermined condition, the provisional value is determined and stored in the storage unit. can do.
(7) The hysteresis acquisition device acquires the hysteresis width before the Lissajous waveform representing the relationship between the steering amount and the steering-related force is generated. Any one of (1) to (6) The power steering device described in 1.
In this power steering apparatus, the hysteresis width can be acquired when both the increase-side representative value and the decrease-side representative value are acquired for at least one divided region. Since the hysteresis width can be acquired before the Lissajous waveform is created, the time required to acquire the hysteresis width can be shortened in this way.
On the other hand, after acquiring multiple hysteresis widths based on multiple pairs of increasing side representative values and decreasing side representative values, the average value of them is set as the hysteresis width, or after the Lissajous waveform is created, the increasing side of the same divided area The absolute value of the difference between the representative value and the decreasing side representative value can be acquired as the hysteresis width.

(8) An auxiliary force control device that controls the auxiliary force by controlling the actuator based on both an actual hysteresis width acquired by the hysteresis width acquisition device and a standard hysteresis width predetermined for the vehicle. The power steering device according to any one of (1) to (7).
When the actuator is controlled based on the standard hysteresis width, when the actual hysteresis width is larger than the standard hysteresis width, the driver feels that the steering is heavy, and when the actual hysteresis width is smaller, the steering is light. I feel.
On the other hand, if the actuator is controlled based on both the actual hysteresis width and the standard hysteresis width, it can be steered with the same steering feeling, for example.
(9) The auxiliary force control device determines, as a control value, a sum of a standard control value determined based on the standard hysteresis width and a correction value determined based on a difference between the standard hysteresis width and the actual hysteresis width. The power steering apparatus according to item (8), including a control value determining unit.
The standard control value is acquired based on the standard hysteresis width, and is acquired regardless of whether the actual hysteresis width changes. The correction value is acquired based on the actual hysteresis width and the standard hysteresis width, and the sum of the standard control value and the correction value is used as the control value.
In this way, if the control value is acquired as the sum of the standard control value and the correction value, the control value corresponding to the change in the actual hysteresis width can be obtained without complicating the calculation when determining the control value. Can be determined.
Since the control value for the actuator has a magnitude corresponding to the target value of the auxiliary force, it can be considered that the determination of the control value and the determination of the target value of the auxiliary force are the same. The same applies to the correction value, and the determination of the correction value of the control value and the determination of the correction value of the target value of the auxiliary force are the same, and in the following description, these will be used to represent the same meaning. .
(10) The control value determination unit includes a correction value determination unit that determines the correction value corresponding to both the steering-related force and the steering amount, according to item (8) or (9) Power steering device.
For example, it is desirable to determine whether the auxiliary force is excessive or insufficient due to the change in the hysteresis width based on the steering related force. However, when the input (steering torque) is set to 0 at a steering position away from the neutral position of the steering member, the steering member approaches the neutral position (the driver is in a state where the steering member is steered from the neutral position). When the hand is released from the steering member, the steering member is returned). However, if the hysteresis width is different, the position of the returned steering member is different. In order to reduce the difference in the returned steering position, it is desirable to determine the correction value based on the steering amount. Therefore, in the power steering apparatus described in this section, the correction value is determined corresponding to both the steering related force and the steering amount.
(11) The correction value determining unit includes means for acquiring a sum of a steering related force corresponding correction value determined based on the steering related force and a steering amount corresponding correction value determined based on the steering amount. The power steering device according to item.
Storing a steering related force correspondence correction value determination table representing the relationship between the steering related force and the steering related force correspondence correction value, and a steering amount correspondence correction value determination table representing the relationship between the steering amount and the steering amount correspondence correction value; Correction values can be obtained in accordance with these tables, and correction values can be determined based on the sum of these values.
It is also possible to store a combined correction value determination table that is a combination of these two tables, and obtain the sum according to the stored combined correction value determination table. The composite correction value determination table may represent the relationship between the steering related force and the composite correction value, or may represent the relationship between the steering amount and the composite correction value.
In any case, the composite correction value determination table is created based on the relationship between the steering amount and the steering related force. For example, the steering related force correspondence correction value determination table and the steering amount correspondence correction value determination table are combined using the relationship in which the steering amount is Qs when the steering related force is Fs. Note that the composite correction value determination table may be a three-dimensional table that represents the relationship between the steering-related force and the steering amount and the correction value.
(12) The power according to (10) or (11), wherein the correction value determining unit determines the correction value based on at least one of a traveling speed of a vehicle and a steering speed of the steering member. Steering device.
When acquiring the correction value, the vehicle speed and the steering speed can be taken into consideration. Since the standard control value is usually determined based on the vehicle speed and the steering speed, it is desirable that the correction value added to the standard control value is also determined based on the vehicle speed and the steering speed.
(13) The correction value determining unit includes a correction value limiting unit that limits the absolute value of the correction value so as not to be larger than ½ of the absolute value of the difference between the actual hysteresis width and the standard hysteresis width. The power steering device according to any one of (10) to (12).
The absolute value of the correction value need not be larger than a value corresponding to the absolute value of the difference between the actual friction force and the standard friction force of the entire steering mechanism. Therefore, it is desirable to limit the absolute value of the correction value so as not to be larger than a value corresponding to the absolute value of the difference between the actual friction force and the standard friction force.
(14) An auxiliary force control device that controls the auxiliary force by controlling the actuator based on a change amount of the actual hysteresis width acquired by the hysteresis width acquisition device (1) to (13) The power steering device according to any one of the above.
The amount of change in the actual hysteresis width corresponds to the amount of change from the standard hysteresis width, the amount of change from the actual hysteresis width acquired last time, and the like. If the assisting force is controlled based on these changes, it is possible to reduce the change in the driver's steering feeling.

(15) A power steering device for giving an output obtained by adding an auxiliary force by an actuator to an input applied to a steering member to a steering wheel,
A hysteresis width acquisition device that acquires a hysteresis width that is a relationship between a steering amount of the steering member and a steering-related force that is one of the input and the output;
An auxiliary force control device for controlling the auxiliary force by controlling the actuator based on both the actual hysteresis width acquired by the hysteresis width acquisition device and a standard hysteresis width predetermined for the vehicle. A power steering device.
The hysteresis width acquisition device may be as described in the above items (1) to (7), but is not limited thereto. For example, a hysteresis width acquisition device that acquires a hysteresis width as described in Patent Document 1 can be employed without acquiring a representative value of output or input for each divided region.
Further, the technical features described in any one of the items (1) to (14) can be employed in the power steering device described in this item.

Hereinafter, a power steering apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. The power steering device in the present embodiment is an electric power steering device.
In FIG. 1, 10 is a steering wheel as a steering member, and 12 is a steering shaft 12. The steering shaft 12 is rotated according to the rotation of the steering wheel 10. The steering shaft 12 is connected to a rack shaft (steering rod) 16 via a gear box 14. The gear box 14 includes a motion conversion mechanism that converts rotation of the steering shaft 12 into linear motion of the rack shaft 16. The gear box 14 can have, for example, a pinion and a rack.
22 and 24 are steering wheels. The steering wheels 22 and 24 are connected to tie rods 30 and 32 via knuckle arms 26 and 28, and the tie rods 30 and 32 are connected to each other by a rack shaft 16 extending in the left-right direction of the vehicle.
The rack shaft 16 is disposed in the housing 38, and the housing 38 is provided with an electric motor 40 as an actuator and a motion conversion mechanism 42. The rotation of the electric motor 40 is converted into a linear motion by the motion conversion mechanism 42 and transmitted to the rack shaft 16. The motion conversion mechanism 42 also has a function as a driving force transmission mechanism that transmits the driving force of the electric motor 40 to the rack shaft 16. The motion conversion mechanism 42 can have, for example, a ball screw mechanism.
In this way, the rack shaft 16 is applied with an input according to the rotation of the steering shaft 12 and an auxiliary force by the electric motor 40, and is moved in the left-right direction by an output that is the sum of these inputs and the auxiliary force. The steering wheels 22 and 24 are steered.

  The electric motor 40 is controlled based on a command from a steering ECU 50 mainly including a computer. The steering ECU 50 includes an execution unit 52, a storage unit 54, an input / output unit 56, and the like. The input / output unit 56 includes a steering amount sensor 60 that detects a steering angle as a steering amount of the steering wheel 10, a steering torque sensor 62 that detects a steering torque (corresponding to an input) applied to the steering wheel 10, and a traveling speed of the vehicle. A vehicle speed sensor 64 for detecting the yaw rate, a yaw rate sensor 66 for detecting the yaw rate of the vehicle, and the like are connected, and the electric motor 40 is connected via a drive circuit 68. The electric motor 40 can be a brushless motor, for example, and the drive circuit 68 can include an inverter.

In the embodiment, the steering amount sensor 60 detects the rotation angle of the pinion of the gear box 14. If the rotation angle of the pinion is detected, the influence of twisting of the steering shaft 12 is reduced, so that the steering angle of the steering wheel 10 is acquired as compared with the case where the steering amount sensor is provided on the steering shaft 12. Is desirable. Further, the steering amount sensor 60 is referred to as a steering angle from the neutral position (absolute steering angle) if a neutral position (a position where the steering angle is 0) is determined based on a steering angle or the like when the vehicle is in a straight traveling state. There is also). For example, when the yaw rate detected by the yaw rate sensor 66 is substantially 0, it can be assumed that the vehicle is in a straight traveling state and the steering wheel 10 is in the neutral position.
Note that whether or not the vehicle is in a straight traveling state can be acquired based on lateral force, for example, instead of yaw rate. The device is not limited to the yaw rate sensor 66, but may be any device that can detect whether or not the vehicle is traveling straight.
The storage unit 54 stores a control value determination program represented by the flowchart of FIG. 2, a correction value determination table represented by the maps of FIGS. 5 and 6, a gain determination table represented by the maps of FIGS. Is done. A data set is stored when the hysteresis width is acquired.

The driver steers the steering wheel 10 while feeling the steering reaction force. The steering reaction force is a reaction force based on a force acting between the road surface and the tires of the steering wheels 22 and 24 and a reaction force based on a friction force in the entire steering mechanism (mechanism from the steering wheel 10 to the steering wheels 22 and 24). It is the sum of power.
The frictional force of the entire steering mechanism is not always the same for all vehicles due to manufacturing variations and the like. Moreover, it changes due to a temperature change or changes over time. If the frictional force of the entire steering mechanism changes, the reaction force based on it also changes.
The force acting between the road surface and the tire includes a force corresponding to the self-alignment torque, a frictional force between the road surface and the tire, and the like. The force acting between the road surface and the tire is determined by the state of wear of the tire, the state of the road surface (for example, it can be expressed by a friction coefficient, etc.), etc., and certain conditions such as in a region where the side slip angle is small Can be considered to change with a substantially constant gradient as the steering amount (corresponding to the steering angle of the steering wheel) changes. If the force acting between the road surface and the tire changes, the reaction force based on it also changes.

The steering reaction force increases with an increase in the absolute value of the steering angle of the steering wheel 10 and decreases with a decrease in the absolute value, but depending on whether the absolute value of the steering angle increases or decreases. It can be considered that a hysteresis twice as large as the reaction force based on the entire frictional force occurs.
If the tire wear state, road surface condition, etc. are almost the same, the vehicle running state and the steering member steering state are substantially the same, and the side slip angle is in a small region, the absolute value of the steering amount Since the change gradient of the steering reaction force with respect to the change of is constant, the hysteresis width is not necessarily acquired when the steering amount is 0, and can be acquired when the steering amount is other than 0.
In the present embodiment, the “state where the running state and steering state of the vehicle are substantially the same” is a state in which the distortion of the Lissajous waveform representing the relationship between the steering angle and the output is small. In other words, the absolute value of the difference between the output when the steering angle increases and the output when the steering angle decreases can be used as the hysteresis width.

  An example of the relationship between the steering angle θ and the output Tδ is shown in FIG. In FIG. 8, a broken line represents a standard Lissajous waveform acquired in advance for the vehicle, and a solid line represents an actual Lissajous waveform that is a relationship between an actual steering angle and an output. A standard hysteresis width is acquired based on the standard Lissajous waveform, and ½ of the standard hysteresis width is set as the standard friction force Tn. The actual hysteresis width is acquired based on the actual Lissajous waveform, ½ of the actual hysteresis width is set as the actual friction force, and the difference between the actual friction force and the standard friction force Tn is set as the friction force change amount Tf.

When the frictional force of the entire steering mechanism changes and the hysteresis width changes, the steering feeling changes, and the driver feels uncomfortable. Therefore, the control value for the electric motor 40 is determined so that the change in the steering feeling caused by the change in the frictional force of the entire steering mechanism is reduced, that is, the driver can feel that the hysteresis width is constant. Is done.
In the present embodiment, a standard control value that is a control value of the auxiliary force in the case of the standard friction force (standard hysteresis width) is determined, and a difference between the standard friction force and the actual friction force (a variation amount Tf of the friction force). The correction value is determined based on the above, and the sum of the standard control value and the correction value is used as the control value.

The control value determination program represented by the flowchart of FIG. 2 is executed at predetermined time intervals.
In step 1 (hereinafter abbreviated as S1. The same applies to other steps), the steering torque, the steering angle, and the vehicle speed are detected, and in S2, the standard control value Ts is determined. For example, it is determined based on the steering torque, standard frictional force Tn, vehicle speed, steering speed, and the like. In S3, an actual hysteresis width acquisition routine is executed.
Then, in S4, it is determined whether or not the actual hysteresis width is acquired this time. If not acquired, the control value is determined in S5 according to the rule when the actual hysteresis width is not acquired. For example, the standard control value Ts can be set as the control value TM.
On the other hand, when the actual hysteresis width is acquired this time, the correction value Ta is acquired in S6, and in S7, the control value TM is the sum of the standard control value Ts and the correction value Ta (TM = Ts + Ta). In step S8, the electric motor 40 is controlled based on the control value TM.
Since the control value, the correction value, and the like are values according to the target torque (corresponding to the target auxiliary force) for the electric motor 40, it is assumed that the control value and the correction value are values according to the target torque. Represent. In S5, the control value can be determined based on the actual hysteresis width (actual friction force) and the standard friction force acquired last time.

The actual hysteresis width acquisition routine is represented by the flowchart of FIG.
In the present embodiment, the steering allowable range of the steering wheel 10 is divided into a plurality of divided areas, and an average value as a representative value of the output in each divided area is acquired. In the same divided area, the average value of the output when the steering angle decreases is subtracted from the average value of the output when the steering angle increases (the average value at the time of return is subtracted from the average value of the output when cutting). Value) is obtained as the actual hysteresis width.

In S11, the steering angle θ, the steering torque TD, and the vehicle speed V are detected, and the control value (corresponding to the auxiliary torque) TM for the electric motor 40 is acquired. In the present embodiment, since the actual hysteresis width is obtained from the relationship between the steering angle and the output Tδ, the sum of the input TD as the steering torque and the auxiliary force TM from the electric motor 40 is obtained as the output Tδ.
In S12, it is determined whether or not they are in the same divided area at the time of previous detection and at the time of current detection. If it is within the same divided area, the output Tδ is obtained in S13, and the average value <Tδ> of the output in the divided area, the maximum value and the minimum value of the vehicle speed are acquired, and these are temporarily stored. The Each of the divided areas is represented by a steering angle (referred to as a pitch angle θn) representing the divided area.

If the divided areas change between the previous detection and the current detection, it is determined in S14 whether or not the direction of change in the steering angle is the same. It is determined whether or not the direction of change of the divided areas (the direction in which the pitch angle increases or the direction in which the pitch angle increases) is the same between the case where S14 is executed last time and the case where it is executed this time.
If the direction of change is the same, the determination in S14 is YES, and in S15, it is determined whether or not it has continuously changed N times or more in the same direction after switching. If it is before switching, the determination is NO, and in S16, it is determined whether or not the effective condition A is satisfied. If satisfied, in S17, the output temporarily stored in S13 is stored. The average value <Tδ>, the maximum value Vmax of the vehicle speed, and the minimum value Vmin are determined and stored together with the pitch angle θn. Hereinafter, a combination of (average output value <Tδ>, maximum vehicle speed value Vnax, minimum value Vmin) and the pitch angle θn for the same divided region is referred to as a data set. The data set includes a data set in which each data is determined and stored, and a data set temporarily stored. As will be described later, each data may be an invalid value. Further, the data detected this time is processed in S13 and temporarily stored.

In this embodiment, the effective condition A is set in S16 in the data set tentatively stored in S13 immediately before (in the data set for the immediately preceding divided region) (i) the minimum value Vmin of the vehicle speed is set. It is above the speed, (ii) the value obtained by subtracting the minimum value Vmin from the maximum value Vmax of the vehicle speed is below the set value, and (iii) the absolute value of the change amount of the steering angle between this time and the previous time It is that it is below the set value (the absolute value of the change speed dθ / dt of the steering angle θ is below the set speed), and when all three of these are satisfied, the effective condition A is satisfied. . When the valid condition A is satisfied, the provisional value (the provisionally stored value) is determined to be valid and determined.
On the other hand, when the valid condition A is not satisfied, that is, when at least one of the above (i) to (iii) is not satisfied, the provisional value is not fixed and is set as an invalid value in S18. The The average value <Tδ> of the output, the maximum value Vmax of the vehicle speed, and the minimum value Vmin are invalid values, and are stored together with the pitch angle θn in S17. A data set containing invalid values is stored. An invalid value is a value that is not possible in practice.
As described above, the steering reaction force is affected by the vehicle speed and the steering speed. Therefore, when the average value of the output acquired in a state where the vehicle speed and the steering speed are largely changed is adopted, the Lissajous waveform that is the relationship between the output and the steering angle is distorted, and the hysteresis width cannot be acquired accurately. Therefore, when the traveling speed, the steering speed, or the like does not satisfy the valid condition A, the provisional value is set to an invalid value so that the hysteresis width is not acquired as will be described later.

  Hereinafter, when the steering angle changes in the same direction, S13 is executed while the steering angle is in the same divided area (at time points P1 to P5 and P6 to 9 in FIG. 7), and each data (average value of output) <Tδ>, maximum value of vehicle speed, minimum value Vmax, Vmin) are acquired and temporarily stored. When the divided area changes (at time points P6 and 10 in FIG. 7), S11, 12, 14 to 17 are executed, and each of the above-mentioned data temporarily stored for the immediately preceding divided area (average value of output <Tδ) >, The maximum value Vmax and the minimum value Vmin of the vehicle speed are stored together with the pitch angle θn. Further, when this program is executed for the first time, if the divided area is changed, S13 is executed after execution of S17, and the detected value is processed and temporarily stored. When it is executed for the first time, the provisional value is not stored, so that the data set is not fixed.

If the direction of change of the steering angle has changed, the determination in S14 is NO, and the provisional value is set to an invalid value in S19. In this case, an invalid value is stored in S17 whether or not the valid condition A is satisfied in S16.
The determination in S14 is NO at time P1 'in FIG. 7, and the data such as the average value <Tδ> of the output tentatively obtained for time P11 to P20 in the same divided area represented by the pitch angle θm is an invalid value. It is said. Since the data for this divided area (return area) is not used when acquiring the hysteresis width, it is an invalid value.
Thereafter, as with the steering wheel 10 returning operation, the provisional value is obtained in the same manner as in the rounding-up operation, and when the valid condition A is satisfied, the provisional value is determined and the data set is stored.

If the number of executions after S14 after switching is equal to or greater than the set number N, that is, if N or more divided areas have changed after switching, the determination in S15 is YES and S20 and subsequent steps are executed. .
In S20, the data set stored in the storage unit is searched for a data set including data having the same pitch angle as the pitch angle included in the data set provisionally stored immediately before. If there is a data set including the same pitch angle, the determination in S21 is YES, and it is determined in S22 whether the effective condition B is satisfied, and in S23, whether the effective condition C is satisfied. .

The valid condition B is (i) the maximum value (or the minimum value) of the vehicle speed included in the data set searched and found in S20 and the maximum value of the vehicle speed included in the data set temporarily stored in S13 (or (Ii) (a) The value obtained by subtracting the minimum value from the maximum value of the vehicle speed in the data set temporarily stored for the immediately preceding divided area is the set value. Or (b) the change speed of the steering angle is less than or equal to the set speed, and the effective condition B is satisfied when both of (i) and (ii) are satisfied. The
The effective condition C is that the minimum value Vmin of the vehicle speed included in the data set temporarily stored for the immediately preceding divided region is equal to or greater than the set value. If this is satisfied, the effective condition C is assumed to be satisfied. The
When the valid conditions B and C are satisfied, in S24, the output average value <Tδ> included in the data set found in S20 and the data set temporarily stored for the immediately preceding divided region are included. The absolute value of the difference between the output average value and the provisional value <Tδ> is acquired as the hysteresis width. Further, 1/2 of the hysteresis width is the actual friction force.
When the effective conditions B and C are satisfied, the provisional value of the immediately preceding divided region is valid, and in the same divided region, the environment (the vehicle running state and This is a case where it is considered that the hysteresis width can be accurately obtained.

On the other hand, when an invalid value is included in the data set searched in S20, (i) of the valid condition B is not satisfied, so the determination in S22 is NO and the hysteresis width is acquired. There is no.
In FIG. 7, when the determination in S15 is YES at time P11 ′, a data set including the same pitch angle θ4 as the pitch angle θ4 representing the immediately preceding divided region is searched. When a data set including the same pitch angle is found, an average value <T4> of outputs included in the data set and an average value <T4 ′> of outputs temporarily stored for the immediately preceding divided region The absolute value of the difference is obtained.
Data sets for time points P7 'to P10' are determined and stored in the execution of S17.

In this way, according to the present embodiment, the average value <Tδ> of the output for each divided region is obtained and obtained based on the average value <Tδ> of the output. Therefore, based on each value of the output As compared with the case, the hysteresis width can be obtained accurately.
Further, the hysteresis width is acquired from the relationship between the output and the steering angle, and is acquired based on the result reflecting the assist control. Therefore, it is possible to acquire the hysteresis width more accurately than when acquiring based on the relationship between the input and the steering angle.
Further, the actual hysteresis width can be acquired before the Lissajous waveform that is the relationship between the output and the steering amount is created. Therefore, if the hysteresis width is acquired before the closed curve is created, the actual hysteresis width can be acquired earlier than in the power steering device described in Patent Document 1.

  The hysteresis width acquired for one divided area can be adopted as the actual hysteresis width. However, the hysteresis width is acquired for each of the plurality of divided areas, and the average value of the plurality of hysteresis widths is used as the actual hysteresis width. It can also be adopted. It is also possible to acquire the hysteresis width until the Lissajous waveform of the relationship between the output and the steering angle is completed, and employ the average value of these as the actual hysteresis width.

The correction value in S6 is determined according to the execution of the correction value determination routine shown in the flowchart of FIG. In S41, the output correspondence correction value Ta1 is determined based on the output and the table (output correspondence correction value determination table) represented in the map of FIG. 5, and in S42, the steering angle θ is represented by the map of FIG. A steering angle correspondence correction value Ta2 is determined based on the table (steering angle correspondence correction value determination table). In S43, the sum of the output correspondence correction value Ta1 and the steering angle correspondence correction value Ta2 (output / steering angle correspondence correction). The value obtained by multiplying the correction value corresponding to the output / steering angle by the gain k is set as the correction value Ta.
Ta = k · (Ta1 + Ta2)

For example, as shown in FIG. 8, when the actual hysteresis width is larger than the standard hysteresis width, it is desirable to increase the assisting force in the same direction as the steering direction when the steering wheel 10 is steered. The output correspondence correction value determination table in FIG. 5 is for realizing this. In the table, when the output increases, the absolute value of the correction value increases in the same direction as the output direction, and then becomes constant. Become. In FIG. 5, the output α is a very small value and is a value determined by the dead band of the steering torque sensor 62 or the like.
Further, the steering angle correspondence correction value is obtained for the following reason. For example, when the hand is released in a state where it is cut to point P in FIG. 8 (when both input and auxiliary force are set to 0), the control value for the electric motor 40 is based on the standard control value in the case of the standard hysteresis width. If determined, the steering wheel 10 returns to the steering position θ0, but if the actual hysteresis width is larger than the standard hysteresis width as shown by the solid line, it returns only to θa. In this case, when the correction value is determined based on the output correspondence correction value determination table of FIG. 5 (without considering the steering angle), the correction value becomes 0, the steering feeling changes, and the driver Feel something is wrong. On the other hand, based on the steering angle correspondence correction value determination table of FIG. 6, the correction value is not 0, and for example, the steering position of the steering wheel 10 can be returned to θ0 (the auxiliary force of the electric motor 40 is returned in the return direction). The change in steering feeling can be suppressed. In the steering angle corresponding correction value determination table of FIG. 6, when the steering angle increases, the absolute value of the correction value increases in the opposite direction to the steering direction and thereafter becomes constant.

The relationship between the output / steering angle correspondence correction value and the steering angle is shown in FIGS. 11 and 12 show the output correspondence correction value determination table of FIG. 5 and the steering angle correspondence correction value determination table of FIG. 6, and after the output exceeds β of FIG. 5, the steering angle reaches a in FIG. 6. It was synthesized assuming that. When the steering wheel 10 is increased, the table shown in FIG. 11 is created, and when returning, the table shown in FIG. 12 is created.
From FIGS. 11 and 12, it is clear that the assisting force according to the correction value is applied in the direction of assisting the driver's steering when increasing or returning.
Further, in FIG. 5, when the output is β, the output corresponding correction value is doubled as the frictional force change amount Tf (2Tf), as shown in FIG. 11, when the steering angle is equal to or greater than b. This is to avoid that the steering angle correspondence correction value (Ta1 + Ta2) is smaller than the frictional force change amount Tf.

  A limit can also be set when determining the output / steering angle correspondence correction value. FIG. 13 shows a table created by limiting the absolute value of the output / steering angle correspondence correction value so as not to be larger than the frictional force change amount Tf. This is because the necessity of adding a correction value larger than the correction value corresponding to the difference between the actual friction force and the standard friction force is low, and if the correction value is too large, the steering feeling is lowered.

A value obtained by multiplying the output / steering angle correspondence correction value (Ta1 + Ta2) thus obtained by the gain k is set as the correction value Ta, and is added to the standard control value Ts to obtain the control value TM. The gain k is a vehicle speed corresponding gain kv acquired according to the vehicle speed corresponding gain determination table represented by the map of FIG. 9 and a steering speed corresponding gain kθ acquired according to the steering speed corresponding gain determination table represented by the map of FIG. A value obtained by multiplying by.
k = kv · kθ
The vehicle speed-corresponding gain kv is a value that becomes smaller when the vehicle speed is high than when it is low. Specifically, as shown in FIG. 9, the vehicle speed increases as the vehicle speed increases in a region lower than the vehicle speed V1, remains constant in the region between the vehicle speeds V1 and V2, and the vehicle speed increases in the region above the vehicle speed V2. It is a value that decreases with an increase. Thereby, it is possible to avoid an excessive assist force when the vehicle speed is high.
The steering angle-corresponding gain kθ is a value that becomes larger when the steering speed is high than when the steering speed is high, thereby suppressing a turning delay when the steering speed is high.
It is not essential to calculate the correction value by multiplying the gain, but when the standard control value is determined in consideration of the vehicle speed and the steering speed, the correction value is also determined in consideration of the vehicle speed and the steering speed. It is desirable to do.

  Thus, in the present embodiment, the control value is determined by adding the correction value determined based on the amount of change from the standard friction force of the friction force of the entire steering mechanism to the standard control value. A change in steering feeling due to a change in force can be suppressed. Further, the calculation can be facilitated by determining the control value by adding the correction value to the standard control value, compared to the case where the control value is determined in accordance with the change in the frictional force.

As described above, in the present embodiment, the hysteresis width acquisition device is configured by the portion that stores S3 of the actuator control program of the steering ECU 50, the portion that executes it, etc., and among the hysteresis width acquisition devices, S16, 17, and 18 are included. Steering related force representative value acquisition means is constituted by a part for storing the above, a part for executing the part and the like. The steering torque sensor 62, a portion that stores S13 of the steering ECU 50, a portion that executes the steering torque sensor 62, a portion that executes the steering, and the like constitute a steering related force acquisition device.
Furthermore, an auxiliary force control device is configured by a portion that stores an actuator control program of the steering ECU 50, a portion that executes the program, and the like. In addition, the control value determining unit is configured by a part that stores S1 to 7 of the auxiliary force control device, a part that executes the control value, and the correction value is determined by a part that stores S6 and a part that executes S6 of the control value determining unit The part is composed.

In the above-described embodiment, the gain k is a product value of the vehicle speed-corresponding gain kv and the steering speed-corresponding gain kθ. However, either the vehicle speed-corresponding gain kv or the steering speed-corresponding gain kθ is set as the gain k. Also good. Further, it is not essential to multiply the output and steering angle correspondence correction value by the gain k.
Furthermore, in the above-described embodiment, the output correspondence correction value and the steering angle correspondence correction value are acquired, and the sum of these is acquired. However, the table of FIG. It is possible to memorize and determine the output / steering angle correspondence correction value according to these tables. In the above embodiment, it is assumed that the table shown in FIGS. 11, 12 or 13 is the table shown in FIGS. 5 and 6, and that the steering angle reaches a in FIG. 6 after the output exceeds β in FIG. Although it was created by combining, assuming that the steering angle is a when the output is β, it is assumed that the steering angle is smaller than a even if the output reaches β. May be synthesized.

Moreover, in the said embodiment, although the average value of the output for every division area was made into the representative value, it is not restricted to it. A value obtained by statistically processing the output can be used as a representative value. For example, a value considering the output distribution can be used as a representative value, or an intermediate value between the maximum value and the minimum value can be used as a representative value.
Furthermore, when comparing the vehicle speeds included in the data sets of the same divided region, the average value of the vehicle speeds can be stored and the average value of the vehicle speeds can be compared.
In the above embodiment, the output is the steering related force, but the input can be the steering related force. In this case, the standard hysteresis width is acquired for the relationship between the input and the steering angle, and the actual hysteresis width is acquired.

Furthermore, the correction value can be a correction value from the previous control value, not a correction value from the standard control value. If the current actual hysteresis width is acquired, the amount of change from the actual hysteresis width at the time of the previous acquisition can be acquired. Therefore, the correction value can be determined based on the amount of change.
In the above embodiment, the actual hysteresis acquisition routine is executed in S3 of the actuator control program. However, the actuator control program and the actual hysteresis acquisition program can be executed separately. . For example, this is effective when the execution cycle times of these two programs are different.
Furthermore, in the said embodiment, although the steering amount sensor 60 detected the rotation angle of a pinion, it is not restricted to it. For example, it may be one that detects the stroke of the rack shaft 16 or one that detects the steering angle of the wheel. Alternatively, the rotation angle of the steering shaft 12 may be detected.
Furthermore, although the case where the present invention is applied to a power steering apparatus in which the auxiliary force by the electric motor 40 is directly applied to the rack shaft 16 has been described, the present invention is applied to a power steering apparatus in which the auxiliary force is applied to the steering shaft 12. You can also. Furthermore, the present invention can also be applied to a power steering device in which an auxiliary force by hydraulic pressure is applied to the rack shaft. The auxiliary force applied to the rack shaft is controlled by controlling the hydraulic pressure.
In addition to the above-described embodiments, the present invention can be carried out in various modifications and improvements based on the knowledge of those skilled in the art.

1 is a diagram conceptually illustrating an entire power steering apparatus according to an embodiment of the present invention. It is a flowchart showing the actuator control program memorize | stored in the memory | storage part of steering ECU of the said power steering apparatus. It is a flowchart showing a part of said actuator control program. It is a flowchart showing a part of said actuator control program. It is a map showing the output corresponding | compatible correction value determination table memorize | stored in the said memory | storage part. It is a map showing the steering angle corresponding | compatible correction value determination table memorize | stored in the said memory | storage part. It is a figure which shows typically the method of acquiring frictional force in this power steering apparatus. In this power steering device, it is a figure showing the relation between a steering angle and steering torque. It is a map which shows the vehicle speed corresponding | compatible gain determination table memorize | stored in the said memory | storage part. It is a map which shows the steering speed corresponding | compatible gain determination table memorize | stored in the said memory | storage part. In this power steering device, it is a figure showing typically the method of determining a correction value at the time of rounding up. In this power steering device, it is a figure showing typically a method of determining a correction value at the time of return. It is a figure which shows the method of providing a limit in a correction value and determining in this power steering apparatus.

Explanation of symbols

10: Steering wheel 12: Steering shaft 16: Rack shaft 40: Electric motor 50: Steering ECU 60: Steering amount sensor 62: Steering torque sensor 64: Vehicle speed sensor

Claims (8)

A power steering device for giving an output, which is obtained by adding an auxiliary force by an actuator to an input applied to a steering member, to a steering wheel,
A steering amount detection device for detecting a steering amount of the steering member;
A steering-related force acquisition device that acquires a steering-related force that is one of the input and the output;
When the steering amount detected by the steering amount detection device belongs to each of a plurality of divided areas determined by dividing at least a part of the steering allowable range of the steering member into a plurality, by the steering related force acquisition device It has steering related force representative value acquisition means for acquiring a representative value of the acquired steering related force, and is acquired when the absolute value of the steering amount increases in the same divided region of the plurality of divided regions. Hysteresis is the absolute value of the difference between the increasing representative value that is the representative value of the steering related force and the decreasing representative value that is the representative value of the steering related force that is acquired when the absolute value of the steering amount decreases. A power steering device comprising a hysteresis width acquisition device that acquires the width. The power steering according to claim 1, wherein the hysteresis width acquisition device acquires the hysteresis width when at least one of a traveling state of a vehicle and a steering state of the steering member satisfies a predetermined condition. apparatus. The conditions are: (a) the absolute value of the change rate of the steering amount is not more than a set steering speed, and (b) the amount of decrease from the peak value of the absolute value of the steering amount is not less than the set amount. The power steering device according to claim 2, wherein the hysteresis width acquisition device acquires the hysteresis width when the condition is satisfied. A vehicle speed detecting device for detecting a traveling speed of the vehicle, wherein the condition is (a) a vehicle speed detected by the vehicle speed detecting device when the absolute value of the steering amount increases in the same divided region of the steering amount; When the absolute value of the difference between the representative value of the vehicle speed and the representative value of the vehicle speed when the absolute value of the steering amount decreases is equal to or less than a set value, and (b) when the steering amount is in the same divided region, In each of the cases where the absolute value of the steering amount increases and decreases, the minimum value of the vehicle speed is equal to or higher than a set speed, and (c) when the steering amount is in the same divided region, the steering The hysteresis width acquisition includes at least one of a value obtained by subtracting a minimum value of the vehicle speed from a maximum value of the vehicle speed being equal to or less than a set value in each of the case where the absolute value of the quantity increases and the case where the absolute value of the quantity decreases If the equipment meets that condition Its power steering apparatus according to claim 2 or 3 the hysteresis width and acquires. An auxiliary force control device that controls the auxiliary force by controlling the actuator based on both an actual hysteresis width acquired by the hysteresis width acquisition device and a standard hysteresis width predetermined for a vehicle. The power steering apparatus according to any one of 1 to 4. Control value determination in which the auxiliary force control device determines, as a control value, a sum of a standard control value determined based on the standard hysteresis width and a correction value determined based on a difference between the standard hysteresis width and the actual hysteresis width The power steering apparatus according to claim 5, comprising a portion. The power steering apparatus according to claim 6, wherein the control value determining unit includes a correction value determining unit that determines the correction value corresponding to both the steering-related force and the steering amount. 5. The apparatus according to claim 1, further comprising an auxiliary force control device that controls the auxiliary force by controlling the actuator based on a change amount of the actual hysteresis width acquired by the hysteresis width acquisition device. Power steering device.

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