JP4243847B2 - Vehicle steering system - Google Patents

Description

  The present invention relates to a vehicle steering apparatus in which a ratio between a steering speed at which a driver operates a steering operation member and a displacement speed of a movable member that is displaced to steer a wheel can be changed by a motor. In particular, the present invention relates to a technique for automatically controlling the turning angle of a wheel.

  A vehicle steering apparatus is generally configured to include an operation mechanism operated by a driver and a turning mechanism for turning wheels.

  The operation mechanism normally includes a steering operation member that is operated by a driver, and a movable member that is displaced together with the steering operation member. An example of the steering operation member is a steering wheel, and an example of the movable member is a steering shaft.

  On the other hand, the steering mechanism is typically configured to include a first movable member that is displaced based on a steering operation of the steering operation member by the driver, and a second movable member that is displaced together with the wheels.

  An example of the steering mechanism employs a rack and pinion system. In this example, the first movable member is a pinion (an example of a rotating member), and the second movable member is a rack (an example of a linear displacement member). Each is applicable. Both the pinion and the rack are a kind of gear.

  In this vehicle steering device, for example, the steering of the vehicle is partially or completely electrically controlled for the purpose of improving the steering feeling of the driver, the steering characteristics of the vehicle, the steering stability, the vehicle stability, etc. Research and development of technology to do is being done.

  A first conventional example of a device for partially or completely electrically controlling the steering of a vehicle is called electric power steering. According to this electric power steering, using the electric motor or the pressure source as a power source, the magnitude of the assist torque applied to the steering device in order to reduce the steering torque applied to the steering operation member by the driver is electrically controlled. Is done. This type of steering device is referred to as electric power steering, particularly when the power source is an electric motor.

Japanese Patent Application Laid-Open No. H10-228867 describes a second conventional example in which steering of a vehicle is partially or completely electrically controlled. This conventional example is a steering device of a type in which a so-called steering gear ratio is variable. Specifically, the motor changes the ratio between the steering speed at which the driver operates the steering operation member and the displacement speed of the movable member that is displaced to steer the wheels. If this conventional example is implemented, it becomes easy to switch the steering feeling of the driver between a sharp steering feeling and an insensitive steering feeling according to the situation, purpose, and the like.
JP-A-11-78945

  In the second conventional example described above, the turning angle of the wheel is controlled by using the motor based on the steering angle at which the driver operates the steering operation member. That is, in this conventional example, the turning angle of the wheel is controlled depending on the steering operation of the driver.

  On the other hand, the present inventors have studied active steering for controlling the turning angle of the wheel without depending on the steering operation of the driver by effectively using the motor. As a result, the present inventors have noticed that when active steering is executed and the operating force of the steering mechanism changes, the change is transmitted to the driver via the steering operation member. That is, it has been noticed that a change in steering reaction force due to active steering occurs. Therefore, when active steering is executed, the driver may feel uncomfortable.

  This possibility tends to be particularly noticeable when active steering is executed in a steering holding state in which the driver holds the steering operation member in the same state. This is because in a state where the steering angle is transitional, the steering reaction force changes with the steering angle in the first place, so it is difficult to distinguish the change due to active steering from the total change in the steering reaction force from other changes. On the other hand, since the steering reaction force is steady in the steering-holding state in the first place, when active steering is executed and the steering reaction force changes, the driver can easily feel the change.

  Based on the knowledge described above, the present invention is for a vehicle in which the ratio of the steering speed at which the driver operates the steering operation member and the displacement speed of the movable member displaced to steer the wheels can be changed by a motor. An object of the steering apparatus is to execute active steering that changes the turning angle of a wheel without depending on the steering operation of the driver while reducing the uncomfortable feeling given to the driver.

  The following aspects are obtained by the present invention. Each aspect is divided into sections, each section is given a number, and is described in a form that cites other section numbers as necessary. This is to facilitate understanding of some of the technical features that the present invention can employ and combinations thereof, and the technical features that can be employed by the present invention and combinations thereof are limited to the following embodiments. Should not be interpreted. That is, although not described in the following embodiments, it should be construed that it is not impeded to appropriately extract and employ the technical features described in the present specification as the technical features of the present invention.

Further, describing each section in the form of quoting the numbers of the other sections does not necessarily prevent the technical features described in each section from being separated from the technical features described in the other sections. It should not be construed as meaning, but it should be construed that the technical features described in each section can be appropriately made independent depending on their properties.
(1) A vehicle steering apparatus for steering a vehicle by changing a turning angle of a wheel based on a steering operation of a steering operation member by a driver,
The vehicle steering device superimposes a first change resulting from a change in frictional force inside the vehicle steering device and a second change resulting from a change in frictional force between the tire of the wheel and the road surface. In particular, it has a steering characteristic generated in a steering reaction force acting on the driver from the steering operation member,
A steering mechanism for steering the vehicle by a first movable member;
A ratio changing mechanism for changing a ratio between a steering speed at which a driver operates the steering steering member and a displacement speed of the first movable member by a motor capable of driving the first movable member;
An assist mechanism for applying to the vehicle steering device an assist torque for reducing a steering torque applied by the driver to the steering operation member;
A controller that electrically controls the ratio change mechanism and the assist mechanism, and that performs active steering for changing the turning angle via the ratio change mechanism without depending on the steering operation, and when executing the active steering the vehicle steering system comprising as those of the first change that occurs before Kimisao steering reaction force to perform said steering steering reaction force control to reaction force control via the assist mechanism as is suppressed.

  According to this device, automatic steering, that is, active steering, which does not depend on the driver's steering operation, is performed. This active steering is performed, for example, to automatically perform counter-steering in order to improve vehicle stability, or by optimizing the lateral force of each wheel by optimizing the lateral slip angle of each wheel. It can be performed to control the yaw displacement.

Further, according to this apparatus, the steering reaction force is controlled using the assist mechanism when active steering is executed. Here, in a vehicle steering apparatus, for example, as represented by a steering mechanism, a plurality of members (for example, a rack and a pinion, a face gear and a pinion, and a pair of gears) that should transmit force to each other are provided. Are pressed against each other at the contact surfaces. Therefore, a frictional force (hereinafter referred to as “inter-member frictional force”) exists between the contact surfaces of the plurality of members. When the magnitude or direction of the frictional force between the members changes, the change is directly or indirectly transmitted to the driver via the steering operation member, and as a result, the change is transmitted to the driver as a change in the steering reaction force. It will be recognized. On the other hand, according to this apparatus, when active steering is executed , torque that compensates for the change in the steering reaction force according to the first change caused by the change in the internal friction force corresponding to the friction force between the members. There Ru is caused by the assist mechanism.

  Therefore, according to this device, when the assist mechanism is originally mounted on the device, it is not indispensable to mount dedicated hardware on the device in order to control the steering reaction force during active steering. .

  The “steering mechanism” in this section can adopt, for example, a rack and pinion system in which a rack and a pinion mesh with each other. In this case, it can be considered that the first movable member corresponds to a rack. It is possible to think that it corresponds to.

  The “assist mechanism” in this section may be a mechanism that can electrically control the magnitude of the assist torque. Therefore, an electric motor can be used as a power source to control its output torque, or a high pressure source can be used as the power source to control the pressure level using an electrical pressure controller such as an electromagnetic valve. The format can be

The “first movable member” in this section may mean a linear displacement member (for example, a rack) that performs linear displacement, or may mean a rotation member (for example, a pinion) that performs rotational displacement.
(2) The controller is caused by execution of the active steering in a steering holding state where the driver holds the steering operation member so that a steering angle at which the driver operates the steering operation member does not substantially change. The vehicle steering apparatus according to (1), wherein the steering reaction force control is performed so that the first change in the steering reaction force is suppressed.

According to this device, the active steering in the steered state is executed while the first change in the steering reaction force is suppressed. Therefore, according to this device, when active steering is performed in the steering-holding state, the actual steering reaction force transmitted to the driver is transmitted even though the original steering reaction force changes due to the occurrence of the first change. Since the change in the force is suppressed, the driver may feel no discomfort at all or even if the driver feels discomfort.
(3) wherein the controller, the steering based on at least one of the temperature of the steering characteristic and the vehicle steering device of the steering operation member of the operation state and the operation state and the vehicle steering device of the steering mechanism The vehicle steering apparatus according to (1) or (2), wherein reaction force control is performed.

  In this section and the following sections, “steering characteristics” is defined as, for example, the relationship between the input to the steering device, that is, the operating force, and the output from the steering device, that is, the turning angle of the wheel to be steered. It is possible. Here, the input to the steering apparatus is performed on the wheel to be steered, and the magnitude of the input reflects the frictional force between the tire of the wheel and the road surface. The magnitude of the frictional force can be detected as, for example, the operating force of the first movable member (for example, the rack axial force described above).

  Therefore, the “steering characteristic” can be defined as, for example, a relationship between input and output to the steering mechanism. Specifically, the operating force of the first movable member (for example, the axial force of the rack described above, the frictional force between the tire and the road surface) and the operation amount of the first movable member (for example, the straight line of the rack described above). It can be defined as a relationship with the displacement amount.

Furthermore, “steering characteristics” can be defined as the relationship between input and output for the wheel to be steered. Specifically, for example, the operating force of the first movable member (for example, the axial force of the rack described above, the frictional force between the tire and the road surface) and the turning angle of the wheel (the wheel is steered during active steering). It is possible to define the relationship as
(4) before Symbol controller, vehicle steering system according to any one of (1) performing the steering reaction force control as before Symbol second change is inhibited (3).

As described above, in the steering apparatus for a vehicle, part material between the frictional forces are present. The magnitude of the frictional force between the members varies depending on the magnitude of the normal force between the contact surfaces of the plurality of members described above . On the other hand, the direction of the frictional force between the members changes depending on the direction of relative displacement between the plurality of members.

  The direction of the relative displacement reflects the direction of the relative displacement between the steering operation member and the first movable member. For example, when the steering mechanism adopts a rack and pinion system, the direction of the relative displacement is the direction of the relative displacement between the steering operation member and the pinion, and the relative displacement between the pinion and the rack. It is also the direction.

Then, as described above, when the size or orientation of the member between the frictional force is changed, the change is transmitted to the driver via a direct or indirect to the steering operation member, so that the steering reaction the change in the driver It will be recognized as a change in power.

  On the other hand, when active steering is performed and, as a result, the direction of the relative displacement is reversed, the magnitude of the normal force between the contact surfaces is large and suddenly changes. Not only the direction but also the size changes, and the change is recognized by the driver as a change in the steering reaction force. Therefore, a relationship having hysteresis is established between the steering reaction force and the wheel turning angle.

  On the other hand, if the steering angle of the wheel is changed by active steering, the friction force between the tire and the road surface acting between the tire of the wheel and the road surface regardless of whether the friction force between the members described above is changed or not. The operating force of the steering mechanism changes accordingly. This change is also recognized by the driver as a change in the steering reaction force in the same manner as the change in the inter-member friction force. On the other hand, the operating force of the steering mechanism at this time, that is, the friction force between the tire and the road surface is changed so as to have a finite inclination with respect to the steering angle of the wheel. The inclination corresponds to the steering characteristic of the vehicle steering device.

  Therefore, when active steering is executed, there is both inclination and hysteresis between the steering reaction force and the wheel turning angle (for example, the linear displacement amount of the rack and the rotation angle of the pinion). A relationship will be established. Therefore, when active steering is executed, the first change based on the hysteresis width (that is, the change amount of the friction force between the members described above) and the inclination (that is, the change amount of the friction force between the tire and the road surface described above) are obtained. The second change based on this appears in the steering reaction force in a superimposed manner.

In contrast, according to the apparatus according to the present mode, the steering reaction force control such that the second change is suppressed is performed.
(5) said controller, wherein when the steering reaction force control executed, and the steering characteristic of the temperature and the vehicle steering system operating conditions and the vehicle steering device of the steering operation member of the operation with said turning mechanism Compensation torque determining means for determining a compensation torque to be generated as an assist torque by the assist mechanism in order to compensate for a change in the steering reaction force due to the active steering based on at least one of (1) to (1) The vehicle steering apparatus according to any one of the items 4).

  According to this apparatus, in order to suppress a change in the steering reaction force due to the active steering, the compensation torque for compensating the change is determined by the operation state of the steering operation member, the operation state of the steering mechanism, and the vehicle steering. It is determined based on at least one of the temperature of the device and the steering characteristics of the vehicle steering device.

  In this device, when the compensation torque is generated, the steering reaction force is reduced accordingly. Therefore, the absolute value of the compensation torque is determined so as to be equal to the reduction amount of the steering reaction force. The direction or sign of the compensation torque can be determined according to the direction of relative displacement between the steering operation member and the first movable member, as will be described later, for example.

In this apparatus, it is conceivable that the assist mechanism executes the original function, that is, reduction of the steering torque in parallel with the above-described steering reaction force control. In this case, for example, the target value of the assist torque is determined as the sum of a control amount for reducing the steering torque of the driver and a control amount for suppressing a change in the steering reaction force caused by the active steering. Is possible.
(6) The compensation torque determination means includes first determination means for determining the compensation torque based on a relationship between a displacement state of the steering operation member and a displacement state of the first movable member. Vehicle steering system.

  The mode of relative displacement between the steering operation member and the first movable member is determined based on the relationship between the displacement state of the steering operation member and the displacement state of the first movable member. On the other hand, the frictional force between the members described above varies depending on the mode of relative displacement. Therefore, if the compensation torque is determined based on the aspect of the relative displacement, it becomes easy to accurately suppress the change in the steering reaction force due to the active steering.

  Based on such knowledge, in the apparatus according to this section, the compensation torque is determined based on the relationship between the displacement state of the steering operation member and the displacement state of the first movable member.

In this section, the “displacement state” is defined to indicate, for example, whether the corresponding member is stopped or displaced, or to indicate the displacement direction when the corresponding member is displaced. It is possible.
(7) The first determining means is that the steering operation member is substantially stopped when both the steering operation member and the first movable member are displaced in opposite phases to each other. The vehicle steering apparatus according to item (6), further including means for determining the compensation torque so that the absolute value becomes larger than when the first movable member is displaced.

  When the steering operation member and the first movable member are both in a state of being displaced in opposite phases with each other immediately before execution of active steering, when active steering is executed in that state, the steering operation member is The displacement state in the direction opposite to the displacement direction of the first movable member is changed to the displacement state in the same direction as the first movable member.

  On the other hand, immediately before execution of active steering, when the steering operation member is substantially stopped but the first movable member is displaced, active steering is executed in that state. Then, the steering operation member is shifted from a substantially stopped state to a displacement state in the same direction as the displacement direction of the first movable member.

  In the former state transition, since the relative displacement between the steering operation member and the first movable member changes more greatly than the latter state transition, the above-described inter-member frictional force also changes greatly. Therefore, in the former state transition, the torque to be compensated by the assist mechanism is larger than that in the latter state transition.

  Based on the knowledge described above, in the apparatus according to this section, the steering operation member substantially stops when both the steering operation member and the first movable member are displaced in opposite phases. On the other hand, the compensation torque is determined so that the absolute value becomes larger than when the first movable member is displaced.

Therefore, according to this device, it is easy to optimize the compensation torque in relation to the relative displacement mode between the steering operation member and the first movable member.
(8) Based on the physical quantity related to the steering torque and the physical quantity related to the assist torque generated by the assist mechanism, the compensation torque determining means is a value obtained by combining the steering torque and the assist torque. The vehicle according to any one of (5) to (7), including second determining means for determining the compensation torque so that the absolute value becomes larger as the difference between before and after the displacement direction of the steering operation member is reversed is larger. Steering device.

  In general, in a vehicle steering apparatus, a value obtained by combining a steering torque applied to a steering operation member by a driver and an assist torque generated by an assist mechanism is applied to the wheel in a direction in which the wheel is turned. . This composite value changes between before and after the displacement direction of the steering operation member is reversed.

  On the other hand, the displacement of the first movable member hardly follows the displacement of the steering operation member within a short time when the displacement direction of the steering operation member is reversed. Therefore, within that time, the turning angle of the wheel hardly changes, and the tire-road frictional force hardly changes.

  Accordingly, it can be considered that the amount by which the above-described composite value changes between before and after the displacement direction of the steering operation member is reversed substantially represents the maximum amount of change in the friction force between the members.

  Based on such knowledge, in the apparatus according to this section, a value obtained by combining the steering torque and the assist torque based on the physical quantity related to the steering torque and the physical quantity related to the assist torque generated by the assist mechanism. The compensation torque is determined such that the absolute value increases as the difference between before and after the displacement direction of the steering operation member is reversed is large.

  Therefore, according to this apparatus, it is easy to optimize the compensation torque in relation to the magnitude of the frictional force between members that changes due to active steering.

In this section, “physical quantity related to steering torque” does not mean to exclude steering torque itself, but also means to include another physical quantity that can uniquely induce steering torque. This also applies to “physical quantity related to compensation torque”.
(9) The compensation torque determining means includes third determining means for determining the compensation torque based on the temperature of the vehicle steering apparatus so that the absolute value increases as the temperature decreases. The steering apparatus for vehicles according to any one of the items).

  In general, in a vehicle steering system, the magnitude of the above-described frictional force between members varies depending on the temperature of the steering device (particularly, the temperature of the portion where the frictional force between the members is generated). The lower the is, the greater the frictional force between the members.

Based on such knowledge, in the device according to this section, the compensation torque is determined based on the temperature of the device so that the absolute value increases as the temperature decreases. Therefore, according to this apparatus, it becomes easy to optimize the compensation torque in relation to the temperature of the apparatus.
(10) The first controller determines whether or not the driver is in a steered state in which the driver holds the steering operation member in substantially the same state by comparing the steering speed with a first threshold value. A determination and a second determination for determining whether or not the first movable member is in a stopped state by comparing the displacement speed of the first movable member with a second threshold value;
The first and second threshold values are set such that the sensitivity of the first determination result with respect to the steering speed is lower than the sensitivity of the second determination result with respect to the displacement speed of the first movable member. The vehicle steering device according to any one of (5) to (9).

  In this device, a first determination for determining whether or not the steering operation member is in the steering-holding state is performed by comparing the steering speed with the first threshold value, and the displacement speed of the first movable member is further determined. A second determination is made to determine whether or not the first movable member is in a stopped state by comparison with the second threshold value.

  Here, the sensitivity of the result of the first determination with respect to the steering speed (sensitivity that the result of the first determination changes depending on the steering speed) and the sensitivity of the result of the second determination with respect to the displacement speed of the first movable member (the second determination) And the sensitivity with which the result changes depending on the displacement speed of the first movable member).

  Of the above-described frictional force between members and frictional force between the tire and the road surface, particularly the frictional force between members is sensitive to a change in the displacement direction of the first movable member, that is, the sign of the displacement speed. Accordingly, it is important to sensitively determine the displacement state of the first movable member in order to accurately control the compensation torque so that at least a change in the frictional force between the members does not appear in the steering reaction force. Therefore, it is desirable that the sensitivity of the result of the second determination with respect to the displacement speed of the first movable member is sensitive.

  On the other hand, the steering operation is usually classified into one of right-handed, left-handed and steered. In order to control the compensation torque so that at least a change in the frictional force between the members does not appear in the steering reaction force, it is sufficient to determine whether the steering operation corresponds to the right-handed, left-handed or steered state.

  On the other hand, in the steering holding state, it is not realistic that the driver holds the steering operation member so that the steering angle does not change at all, and the steering angle is centered on a certain value (a value other than 0 or 0). Therefore, it is natural to think that the steering speed fluctuates in the minute range around 0 as a result. Such a minute fluctuation is induced, for example, when the steering operation member and the first movable member are connected to each other via an elastic body such as a torque sensor.

  In the steered state, even if the steering angle varies, the first movable member is maintained in the stopped state as long as the steering torque cannot overcome the sum of the friction force between the members and the friction force between the tire and the road surface. Unless the steering torque is applied to the steering member by the driver so large that the first movable member is shifted from the stopped state to the displaced state, it is the driver's intention to classify such steering operation as a steering wheel. It also matches.

  Therefore, unlike the case of the first determination, it is desirable that the sensitivity of the result of the second determination with respect to the steering speed is insensitive in order to stably determine the steering operation as one of the above three states.

  Based on the knowledge described above, in the apparatus according to this section, the first threshold value to be compared with the steering speed in the first determination and the first threshold value to be compared with the displacement speed of the first movable member in the second determination. The second threshold is set so that the sensitivity of the first determination result with respect to the steering speed is lower than the sensitivity of the second determination result with respect to the displacement speed of the first movable member.

Therefore, according to this apparatus, both the request for the state determination of the steering operation member based on the steering speed and the request for the state determination of the first movable member based on the displacement speed of the first movable member, which do not coincide with each other. It becomes easy to make.
(11) The compensation torque determination means includes fourth determination means for determining the compensation torque so as to have a region that continuously changes in accordance with a displacement speed of the first movable member. The vehicle steering device according to any one of the items.

According to this apparatus, the compensation torque does not have to be suddenly changed despite the sudden change in the displacement speed of the first movable member. Therefore, according to this device, it is possible to prevent an impact caused by a sudden change in the displacement speed of the first movable member from being generated in the steering reaction force.
(12) The compensation torque determination means includes fifth determination means for determining the compensation torque so as to have a region that continuously changes in accordance with the steering speed. The steering apparatus for vehicles as described.

  For example, when determining whether or not the steering operation is steering-holding by comparing the steering speed with a threshold value and determining the compensation torque according to the result, the steering speed is centered on the threshold value. As a result, the steering operation state determination result also fluctuates, and as a result, the compensation torque also fluctuates.

  On the other hand, instead of discretely determining the steering operation state to determine the compensation torque discontinuously, such discrete state determination is omitted and continuous compensation is made according to the steering speed. If the torque is determined, it is easy to avoid the compensation torque resulting from the fluctuation of the steering speed and the fluctuation of the steering reaction force.

Based on such knowledge, in the apparatus according to this section, the compensation torque is determined so as to have a region that continuously changes according to the steering speed.
(13) The compensation torque determining means is configured so that the driver holds the steering operation member in substantially the same state so as to maintain the traveling angle of the vehicle, and the driver changes the traveling angle of the vehicle. Is a region that changes with a hysteresis with respect to a change in the steering speed when the steering operation member transitions between a steered state in which the steering operation member is operated so that the steering angle thereof changes. The vehicle steering apparatus according to any one of (5) to (12), further including sixth determination means for determining the compensation torque so as to include

  According to the device according to the above item (12), the compensation torque is continuously determined according to the steering speed. However, the steering operation member is in the steered state and the steered state (right-handed state or left-handed state). Since the transition frequently occurs, if the compensation torque follows the frequent transition, the fluctuation tendency of the compensation torque increases.

  On the other hand, in the apparatus according to this aspect, when the steering operation member transitions between the steered state and the steered state, the device has a region that changes with hysteresis with respect to the change in the steering speed. Thus, the compensation torque is determined.

Therefore, according to this device, it is not necessary for the compensation torque to respond sensitively to the state transition of the steering operation member, and it is easy to suppress frequent changes in the compensation torque.
(14) A seventh determination in which the compensation torque determination means determines the compensation torque based on an amount by which a physical quantity related to the steering torque has changed until the first movable member shifts from a stop state to a displacement state. The vehicle steering apparatus according to any one of (5) to (13), including means.

  If the steering operation member and the first movable member are completely rigidly coupled to each other in the steering apparatus, the steering angle of the steering operation member and the displacement amount (rotational displacement amount or linear displacement amount) of the first movable member. The first movable member is always displaced whenever the steering angle changes.

  However, in reality, it is natural to think that the steering operation member and the first movable member are elastically connected. Therefore, even if the steering angle changes, the first movable member may be maintained in a stopped state without being displaced. In this case, a plurality of steering angles correspond to one displacement amount of the first movable member, and among the plurality of steering angles, one displacement amount of the first movable member corresponds to one displacement amount. It can be considered that there is one theoretical steering angle that is theoretically determined. This theoretical steering angle corresponds to a steering angle corresponding to a certain amount of displacement of the first movable member when the steering operation member and the first movable member are completely rigidly coupled.

  In order to compensate the change in the steering reaction force due to the active steering by the assist torque, when the compensation torque is determined on the assumption that the actual steering angle matches the theoretical steering angle, the actual steering angle actually matches the theoretical steering angle. If not, an error occurs in the compensation torque due to the mismatch.

  Specifically, a state in which the actual steering angle is deviated to an increase side from the theoretical steering angle, that is, one theoretical steering in which the actual steering torque theoretically corresponds to a certain amount of displacement of the first movable member. Assume a case where active steering is started in a state where the torque is deviated from the torque. This case apparently corresponds to a case where active steering is started in a state where the driver is generating assist torque by himself / herself.

  In this case, the steering reaction force control is executed in spite of the presence of the deviation of the actual steering torque, and as a result, the same compensation torque determined on the assumption that the actual steering angle coincides with the theoretical steering angle. When the compensation torque is generated by the assist mechanism, the generated assist torque becomes excessive, and the reduction amount of the steering torque, that is, the steering reaction force becomes excessive.

  Therefore, if there is a possibility that active steering may start in a state where the actual steering torque deviates from the theoretical steering torque, the amount of deviation of the actual steering torque from the theoretical steering torque is obtained, and the compensation torque is estimated accordingly. Is desirable in order to accurately suppress the change in the steering reaction force due to the active steering.

  On the other hand, the amount of deviation of the actual steering torque from the theoretical steering torque is, for example, during the transition from the state where both the steering operation member and the first movable member are stopped to the state where at least the first movable member is displaced. Equal to the amount of torque change.

  Based on the knowledge described above, in the apparatus according to this section, the compensation torque is determined based on the amount of change in the physical quantity related to the steering torque before the first movable member shifts from the stopped state to the displaced state. .

  Therefore, according to this device, it is easy to accurately determine the compensation torque by accurately predicting the change in the steering reaction force caused by the active steering.

In this section, “physical quantity related to steering torque” does not mean to exclude steering torque itself, but also means to include another physical quantity that can uniquely induce steering torque. An example of such another physical quantity is a steering angle.
(15) The controller is
Smoothing means for smoothing a plurality of compensation torques sequentially determined by the compensation torque determining means;
The vehicle steering apparatus according to any one of (5) to (14), including control means for controlling the assist mechanism so that the smoothed compensation torque is realized.

  According to this device, since the compensation torque realized by the assist mechanism is smoothed, the steering reaction force does not change discontinuously by the steering reaction force control. For example, the steering reaction force control does not cause an overshoot or undershoot in the steering reaction force, so that the steering feeling does not deteriorate during the steering reaction force control.

An example of the “smoothing means” in this section is a low-pass filter realized by hardware or software.
(16) The compensation torque determining means determines the compensation torque based on a physical quantity related to the operating force of the first movable member so that the absolute value increases as the operating force of the first movable member increases. 8. The vehicle steering apparatus according to any one of (5) to (15), including eight determining means.

  The aforementioned frictional force between members tends to increase according to the force acting between a plurality of members in contact with each other. For example, when the load acting on the tooth surface of the rack and the tooth surface of the pinion that are in contact with each other in the steering mechanism increases, the frictional force between the tooth surfaces increases. If the compensation torque is determined in anticipation of the increase, it becomes easy to reliably suppress the change in the steering reaction force caused by the active steering.

  Based on such knowledge, in the apparatus according to this section, the compensation torque is determined based on the physical quantity related to the operating force of the first movable member so that the absolute value increases as the operating force of the first movable member increases. Is done.

In this section, “physical quantity related to the actuating force of the first movable member” does not mean to exclude the actuating force itself, but also to include another physical quantity that can uniquely induce the actuating force. . Examples of such another physical quantity include assist torque generated by an assist mechanism and steering torque.
(17) Ninth, wherein the compensation torque determining means determines the compensation torque as a combined value of the first partial compensation torque based on the steering speed and the second partial compensation torque based on the displacement speed of the first movable member. The vehicle steering apparatus according to any one of (5) to (16), including a determination unit.
(18) The ninth determination means determines the first and second partial compensation torques so that the first partial compensation torque has a tendency to decrease from the second partial compensation torque. Vehicle steering system.

  When the first partial compensation torque that depends on the steering speed is smaller than the second partial compensation torque that depends on the displacement speed of the first movable member, the steering reaction force increases and the solid feeling of the steering operation increases. Conversely, when the first partial compensation torque is greater than the second partial compensation torque, the steering reaction force decreases and the lightness of the steering operation increases.

  On the other hand, for example, when the controller is designed to perform active steering in order to compensate for a decrease in the running stability of the vehicle, it is better to emphasize the profound feeling of steering operation during active steering. Increase people's sense of security.

Based on such knowledge, in the apparatus according to this section, the first and second partial compensation torques are determined such that the first partial compensation torque has a tendency to decrease from the second partial compensation torque.
(19) The ninth determining means may change the first partial compensation and the second partial compensation so that a decrease amount of the first partial compensation torque with respect to the second partial compensation torque changes according to whether or not a predetermined condition is satisfied. The vehicle steering apparatus according to item (18), wherein torque is determined.

According to this device, for example, in a specific vehicle driving environment (for example, an environment in which the driving stability of the vehicle is lower than that during normal driving), the solid feeling of the steering operation is increased to increase the driver's sense of security. On the other hand, in other environments, it is possible to make the steering characteristics variable, such as increasing the lightness of the steering operation and giving priority to the driver's steering response (turning performance).
(20) A tenth aspect in which the compensation torque determining means determines the compensation torque based on a physical quantity related to the turning angle during execution of the active steering so that an absolute value increases in accordance with the turning angle. The vehicle steering apparatus according to any one of (5) to (19), including a determination unit.

  As described above, when the active steering is executed, a relationship is established between the steering reaction force, that is, the steering torque and the turning angle of the wheel. Therefore, when active steering is executed, a change based on the inclination appears in the steering reaction force. The steering reaction force changes so as to increase according to the turning angle of the wheel.

  On the other hand, in the apparatus according to this section, the compensation torque is determined based on the physical quantity related to the turning angle of the wheel during execution of active steering so that the absolute value increases according to the turning angle. .

Therefore, according to this device, during active steering, a change based on the inclination existing between the steering reaction force and the wheel turning angle is suppressed from appearing in the steering reaction force.
(21) In the tenth determining means, the ratio between the turning angle and the compensation torque during the active steering is in accordance with the ratio between the turning angle and a physical quantity related to the operating force of the first movable member. The vehicle steering apparatus according to item (20), wherein the compensation torque is determined so as to vary.

  The ratio between the turning angle of the wheel and the operating force of the first movable member during active steering, that is, the ratio between the turning angle and the steering torque or the steering reaction force (present between the turning angle and the steering reaction force). Slope) is not always constant, and varies depending on the frictional force between the tire and the road surface. Therefore, if the compensation torque is determined in consideration of such a change in the ratio, it becomes easy to accurately suppress the change in the steering reaction force caused by the active steering.

  Based on such knowledge, in the device according to this section, the ratio between the turning angle of the wheel during active steering and the compensation torque is the ratio between the turning angle and the physical quantity related to the operating force of the first movable member. The compensation torque is determined so as to change in accordance with.

  In this section, “physical quantity related to the actuation force of the first movable member” does not mean to exclude the actuation force itself, but includes another physical quantity that can uniquely induce the actuation force. Such other physical quantities include, for example, a friction force between a tire and a road surface, a friction coefficient, and the like.

In this section, the “ratio” can be set so as to be invariable or variable within the range of the corresponding variable. That is, the relationship between relevant variables can be defined as linear or non-linear.
(22) The ratio changing mechanism may further include a second movable member driven by the steering operation member, and a speed reducer provided between the second movable member and the motor. The vehicle according to any one of (1) to (21), wherein a ratio between a displacement speed of the second movable member and a displacement speed of the first movable member is changed by the motor. Steering device.

According to this apparatus, the ratio change mechanism motor is used to change the ratio between the steering speed and the displacement speed of the first movable member, and to move the first movable member independently of the steering operation. It is possible to both steer the vehicle.
(23) Furthermore,
A steering angle sensor for detecting a steering angle at which a driver operates the steering operation member;
A motor rotation angle sensor for detecting a rotation angle of the motor, and the controller is configured to control the first movable member based on a steering angle and a motor rotation angle respectively detected by the steering angle sensor and the motor rotation angle sensor. The vehicle steering apparatus according to item (22), including displacement amount detection means for detecting a displacement amount of the vehicle.

  In the device according to the item (22), a known relationship is established among the steering angle, the motor rotation angle, and the displacement amount of the first movable member. If this relationship is used, the displacement amount of the first movable member can be derived from the steering angle and the motor rotation angle.

  Based on such knowledge, in the apparatus according to this section, the displacement amount of the first movable member is detected based on the steering angle and the motor rotation angle respectively detected by the steering angle sensor and the motor rotation angle sensor. .

  Therefore, according to this device, by effectively using the steering angle sensor and the motor rotation angle sensor, the displacement amount of the first movable member can be detected without a dedicated sensor. It is easy to save the total number.

  In addition, the technical features described in this section can be implemented separately from the technical features described in other preceding sections.

  Hereinafter, some of more specific embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view showing a hardware configuration of a vehicle steering device (hereinafter simply referred to as “steering device”) according to the first embodiment of the present invention. The steering device includes an operation unit 10 and a steering unit 12. The operation unit 10 includes a steering wheel 14 that is rotated by a driver, and a steering shaft 16 that rotates with the steering wheel 14. On the other hand, the steered portion 12 is a portion for steering the left and right steering wheels 20 (only the right wheel 20 is representatively shown in FIG. 1) located on the front side of the vehicle. .

  Specifically, the steering unit 12 includes a gear ratio changing mechanism 22, a rack and pinion type steering mechanism 24, and an electric power steering 26.

  The steering mechanism 24 includes a rack shaft 30 that is linearly displaced laterally in the vehicle to change the direction of the wheels 20, and a pinion shaft 32 that intersects the rack shaft 30. As shown in FIG. 2, a gear called a rack 34 is formed on the rack shaft 30, while a gear called a pinion 36 is formed on the pinion shaft 32. The rack 34 and the pinion 36 are engaged with each other to form a rack and pinion mechanism 38, whereby the rotational movement of the pinion 36 is converted into the linear movement of the rack 34.

  The gear ratio changing mechanism 22 is a mechanism that electrically changes the steering gear ratio, which is the ratio between the rotational speed of the steering wheel 14, that is, the steering speed, and the rotational speed of the pinion shaft 32. As shown in FIG. 2, the gear ratio changing mechanism 22 includes a housing 40, a motor 42 that is coaxial with the steering shaft 16, and a speed reducer 46 that connects the motor 42 and the pinion shaft 32 to each other. The motor 42 has a stator 48 fixed to the housing 40 and a rotor 50, and the rotor 50 is connected to the pinion shaft 32 via a reduction gear 46.

  The reduction gear 46 is a strain wave gearing type, and includes a control gear 54 that rotates integrally and coaxially with the steering shaft 16, and a driven gear 56 that rotates integrally and coaxially with the pinion shaft 32. . The number of teeth of the driven gear 56 is n less than the number of teeth of the control gear 54. The control gear 54 functions as a stator gear when the steering shaft 16 is in a stopped state.

  The control gear 54 and the driven gear 56 are meshed with the external teeth of the flexible gear 58 at their internal teeth. Since the flexible gear 58 is a metal elastic body having a thin belt shape, the flexible gear 58 can be elastically deformed. The flexible gear 58 has the same number of external teeth as the driven gear 56. Therefore, the driven gear 56 does not generate a rotational speed difference with the flexible gear 58, but the control gear 54 generates it.

  A rigid wave generator 60 having an outer peripheral surface having an elliptical cross section is fitted to the inner peripheral surface of the flexible gear 58 so as to be relatively rotatable. The wave generator 60 is rotated coaxially and integrally with the rotor 50. When the wave generator 60 is rotated, the flexible gear 58 is rotated while the direction of its ellipse is changed by the wave generator 60.

  When the motor 42 and the wave generator 60 make one rotation, the driven gear 56 has n teeth less than the control gear 54 and thus rotates n teeth in the direction opposite to the rotation direction of the motor 42 and the wave generator 60. As a result, a rotational speed difference is generated between the control gear 54 and the driven gear 56 and transmitted to the pinion shaft 32. Thereby, the rotational speed of the pinion shaft 32 is reduced to a speed lower than the rotational speed of the motor 42.

  The electric power steering 26 is coaxially mounted on the rack shaft 30. As shown in FIG. 2, the electric power steering 26 includes a motor 62 coaxial with the rack shaft 30, and a ball screw 64 as a motion conversion mechanism that converts the rotational motion of the motor 62 into linear motion of the rack shaft 30. ing. The motor 62 includes a rotor 66 and a stator (not shown). The rack shaft 30 is inserted coaxially and slidably into the rotor 66, and a ball screw 64 is interposed between the rotor 66 and the rack shaft 30. Has been placed.

  As shown in FIG. 2, a torque sensor 70 is disposed in the middle of the force transmission system from the steering wheel 14 to the pinion shaft 32. The torque sensor 70 detects steering torque (which is equal to the steering reaction force) applied to the steering wheel 14 by the driver by using elastic torsion. Therefore, the steering wheel 14 and the pinion shaft 32 are not completely rigidly connected but are connected to each other so as to be elastically twisted within a certain range.

  As is clear from the above description, in the present embodiment, the steered portion 12 constitutes an example of the “steering mechanism” in the item (1), and the gear ratio changing mechanism 22 is the “ratio changing mechanism” in the same term. The electric power steering 26 constitutes an example of the “assist mechanism” in the same term, and the pinion shaft 32 or the rack shaft 30 constitutes an example of the “first movable member” in the same term. is there.

  As shown in FIG. 2, the gear ratio changing mechanism 22 and the electric power steering 26 are based on the torque sensor 70 and the output signals of the steering angle sensor 72 and the motor rotation angle sensor 74 shown in FIG. "ECU (Electronic Control Unit)") 80. The steering angle sensor 72 detects an angle at which the driver rotates the steering wheel 14 as the steering angle θs. The motor rotation angle sensor 74 is provided in the gear ratio changing mechanism 22 and detects the rotation angle of the rotor 50 of the motor 42 as the motor rotation angle θm.

  As shown in FIG. 3, the ECU 80 is configured mainly by a computer 82. As is well known, the computer 82 includes a CPU 84, a ROM 86, and a RAM 88 connected to each other via a bus 80. Various programs to be executed by the CPU 84 are stored in the ROM 86 in advance. These programs include an active steering program, a power assist control program, a compensation torque determination program, and a pinion angle detection program.

  That is, in this embodiment, the ECU 80 constitutes an example of the “controller” in the item (1).

  The active steering program is executed by the computer 82 by the ECU 80 to perform active steering for changing the turning angle of the wheel 20 via the gear ratio changing mechanism 22 without depending on the steering operation of the driver.

  FIG. 4 conceptually shows the contents of the active steering program in a flowchart. This active steering program is repeatedly executed by the computer 82.

  When executing this active steering program each time, first, in step S1 (hereinafter simply represented by “S1”, the same applies to other steps), a vehicle speed sensor, a wheel speed sensor, and a sensor for detecting the yaw rate of the vehicle. The vehicle state quantity is detected based on an output signal of a vehicle state quantity sensor 92 (see FIG. 3) that detects the vehicle state quantity, such as a sensor that detects the lateral acceleration of the vehicle.

  Next, in S2, it is determined based on the detected vehicle state quantity whether the running stability of the vehicle is lower than that during normal running. If it is assumed that it has not decreased this time, the determination is NO, and one execution of this active steering program is immediately terminated. On the other hand, if it is assumed that the running stability of the vehicle is reduced this time, the determination is YES, and the process proceeds to S3.

  In S3, it is determined that it is necessary to automatically perform counter steering without depending on the steering operation of the driver. This time, in order to improve vehicle stability, it is necessary to control the lateral force of the wheel 20 by controlling the turning angle (lateral slip angle) of the wheel 20 and thereby control the yawing moment of the vehicle. Because.

  Subsequently, in S4, a control amount of the motor 42 suitable for realizing the auto counter steering is determined. The control amount is determined in consideration of the detected vehicle state amount, for example. Thereafter, in S5, the motor 42 is driven based on the determined control amount. Thereby, active steering is performed and it is avoided that the stability of a vehicle falls.

  This completes one execution of this active steering program.

  The power assist control program is executed by the computer 82 in order to cause the electric power steering 26 to generate assist torque for reducing the steering torque of the driver by the ECU 80.

  In the present embodiment, the ECU 80 compensates for the change in the steering reaction force acting on the driver from the steering wheel 14 due to the active steering by the assist torque of the electric power steering 26, thereby enabling the active steering. Steering reaction force control is performed to suppress the resulting change in steering reaction force. The compensation torque determination program is executed by the computer 82 in order to determine the compensation torque that compensates for the change in the steering reaction force caused by the active steering. The power assist control program is executed for the purpose of generating the determined compensation torque by the electric power steering 26 in addition to the purpose of reducing the steering torque.

  In addition, the compensation torque for compensating for the change in the steering reaction force caused by the active steering is specifically the steering reaction force when the steering reaction force may increase due to the active steering. The assist torque that decreases the force is the compensation torque. Conversely, when there is a possibility that the steering reaction force decreases due to the active steering, the assist torque that increases the steering reaction force is the compensation torque.

  FIG. 5 conceptually shows the contents of the power assist control program in a flowchart. This power assist control program is also repeatedly executed.

  When the power assist control program is executed each time, first, in S31, the steering torque is detected based on the output signal of the steering torque sensor 70. Next, in S32, based on the detected steering torque, a basic value Tbase of the assist torque is determined. The basic value Tbase is normally determined to be equal to the detected value of the steering torque.

  Subsequently, in S33, the compensation torque Tcon determined by the execution of the compensation torque determination program is read from the RAM 88. Thereafter, in S34, the final assist torque Tfinal is determined by combining the determined basic value Tbase and the compensation torque Tcon. The final assist torque Tfinal is determined as, for example, the sum of the basic value Tbase and the compensation torque Tcon.

  Subsequently, in S35, the control amount of the motor 62 is determined based on the determined final assist torque Tfinal. Thereafter, in S36, the motor 62 is driven based on the determined control amount. As a result, an appropriate assist torque is generated by the electric power steering 26.

  Thus, one execution of the power assist control program is completed.

  The pinion angle θp, which is the rotation angle of the pinion shaft 32, is used to execute the compensation torque determination program. On the other hand, in the present embodiment, the pinion angle θp is detected not by a dedicated sensor but by calculation using the steering angle θs and the motor rotation angle θm. The pinion angle detection program is executed by the computer 82 for the detection.

  FIG. 6 is a flowchart showing the contents of the pinion angle detection program. This pinion angle detection program is also repeatedly executed.

  When the pinion angle detection program is executed each time, first, in S51, the steering angle θs is detected based on the output signal of the steering angle sensor 72. Next, in S52, based on the output signal of the motor rotation angle sensor 74, the motor rotation angle θm is detected.

  Subsequently, in S53, the sum of the product of the detected value of the motor rotation angle θm and the reduction ratio R of the speed reducer 46 and the detected value of the steering angle θs is calculated and adopted as the pinion angle θp. The reduction ratio R is a ratio between the rotational speed of the motor 42 and the rotational speed of the pinion shaft 32, and is a fixed value.

  This completes one execution of the pinion angle detection program.

  In addition, when it is desired to improve the accuracy of detecting the pinion angle θp by the above calculation, the steering angle θs is determined by the steering angle sensor 72, and the torque of the force transmission system from the steering wheel 14 to the speed reducer 46 is reduced. It is desirable to detect not on the upstream side of the sensor 70 but on the downstream side. According to this aspect, the influence of the twist of the force transmission system does not appear as an error in the calculated value of the pinion angle θp.

  In the present embodiment, in the steering reaction force control, the change in the steering reaction force due to the execution of the active steering is performed in the steering holding state where the driver holds the steering wheel 14 so that the steering angle does not substantially change. Done to suppress. For this purpose, the compensation torque is determined, and the compensation torque determination program is executed by the computer 82 in order to determine the compensation torque.

  On the other hand, in the present embodiment, when the steering apparatus performs active steering in a state where the steering reaction force control is not performed, the first change resulting from the change in the frictional force inside the steering apparatus, and the wheel 20 And the second change resulting from the change in the frictional force between the tire and the road surface are superimposed on the steering reaction force Tre (in this embodiment, the steering reaction force Tre means not a force in a narrow sense but torque). It has a steering characteristic that occurs.

  As shown in FIG. 7, this steering characteristic is a coordinate system in which the horizontal axis represents the steering angle θs (or pinion angle θp (that is, the turning angle of the wheel 20)), and the vertical axis represents the steering reaction force Tre. The steering reaction force Tre is expressed as changing with a finite inclination and hysteresis with respect to the change of the steering angle θs.

  Therefore, in this embodiment, when active steering is executed without steering reaction force control, as shown in FIG. 7, the first change based on the hysteresis width (change based on the above-described change in friction force between members). ΔT1 and the second change based on the inclination (change based on the change in the frictional force between the tire and the road surface) ΔT2 are superimposed on the steering reaction force Tre.

  As described above, the relationship between the steering angle θs and the steering reaction force Tre has been described using the graph shown in FIG. 7. However, when active steering is executed in the steered state, the steering angle θs does not change and the pinion angle θp is not changed. Change. The relationship between the pinion angle θp and the steering reaction force Tre at this time is equivalent to that obtained by replacing the steering angle θs with the pinion angle θp in the graph shown in FIG.

  In FIG. 8, the relationship between the steering angle θs and the steering reaction force Tre is represented by a graph focusing on the amount of the first change ΔT1. As is apparent from this graph, the amount of the first change ΔT1 of the steering reaction force Tre varies depending on the timing at which the change of the steering angle θs is started. This will be described in detail later.

  In the present embodiment, the steering reaction force control is executed such that the first change ΔT1 is suppressed among the first change ΔT1 and the second change ΔT2.

  FIG. 9 conceptually shows the contents of the compensation torque determination program in a flowchart. This compensation torque determination program is also repeatedly executed.

  When the compensation torque determination program is executed each time, the steering angle θs is first detected by the steering angle sensor 72 in S101. Next, in S <b> 102, the pinion angle θp detected by the execution of the pinion angle detection program and stored in the RAM 88 is read from the RAM 88.

  Subsequently, in S103, the steering speed Vs is calculated by subtracting the previous detection value from the current detection value of the steering angle θs. Thereafter, in S104, the pinion speed Vp is calculated by subtracting the previous value from the current value of the pinion angle θp.

  Subsequently, in S105, the inter-member friction torque Tfric generated in the steering wheel 14 based on the above-described inter-member friction force is read from the ROM 86 or the RAM 88. In the present embodiment, the inter-member friction torque Tfric is stored in advance in the ROM 86 as a fixed value. As shown in FIG. 8, the inter-member friction torque Tfric means a half value of the width of the hysteresis with respect to the steering reaction force (torque) Tre.

  Further, FIG. 8 also shows the following steering characteristics.

  That is, if it is assumed that active steering is started in a direction in which the steering reaction force Tre increases in a complete steering holding state (a state in which the steering reaction force Tre is positioned at the center of the hysteresis width), the steering reaction force Tre is ΔT1a. Only increase. That is, the steering reaction force Tre increases by the same amount as the inter-member friction torque Tfric.

  On the other hand, if it is assumed that active steering is started in a direction in which the steering reaction force Tre increases in a steering holding state (a state where the steering reaction force Tre is located at the end position of the hysteresis width) close to the steered state, The steering reaction force Tre is increased by ΔT1b. That is, the steering reaction force Tre increases by the same amount as twice the inter-member friction torque Tfric.

  In any case, the direction in which the steering reaction force Tre changes due to active steering is the relationship between the steering state of the steering wheel 14 before the start of active steering and the steered state of the wheel 20 after the start of active steering. It changes according to.

  Based on the knowledge described above, in S106 of FIG. 9, a coefficient K to be multiplied by the inter-member friction torque Tfric read in S105 is determined.

Specifically, the coefficient K is determined as one of +2, +1, 0, −1 and −2 in accordance with the rules shown in the table of FIG. The rule divides the relationship between the steering state (displacement state) of the steering wheel 14 and the steered state of the wheel 20 (displacement state of the wheel 20, the rack shaft 30 or the pinion shaft 32), and the coefficient K for each case. Is identified. This will be specifically described below.
(1) In the first case, that is, the steering speed Vs is 0 because the steering wheel 14 is in the holding state, and the sign of the pinion speed Vp is positive because the pinion shaft 32 is in the right-handed state. In this case, the coefficient K is determined to be “+1”.
(2) In the second case, that is, the steering speed Vs is 0 because the steering wheel 14 is in the holding state, and the sign of the pinion speed Vp is negative because the pinion shaft 32 is in the left-handed state. In this case, the coefficient K is determined to be “−1”.
(3) In the third case, that is, since the steering wheel 14 is in the left-handed state, the sign of the steering speed Vs is negative, and since the pinion shaft 32 is in the steered state, the pinion speed Vp is 0. In some cases, the coefficient K is determined to be “+1”.
(4) In the fourth case, that is, the sign of the steering speed Vs is negative because the steering wheel 14 is in the left-handed state, and the sign of the pinion speed Vp is in the right-handed state because the pinion shaft 32 is in the right-handed state. If it is positive, the coefficient K is determined to be “+2”.
(5) In the fifth case, that is, the sign of the steering speed Vs is positive because the steering wheel 14 is in the right-handed state, and the pinion speed Vp is 0 because the pinion shaft 32 is in the steered state. In some cases, the coefficient K is determined to be “−1”.
(6) In the sixth case, that is, the sign of the steering speed Vs is positive because the steering wheel 14 is in the right-handed state, and the sign of the pinion speed Vp is in the right-handed state because the pinion shaft 32 is in the left-handed state. If negative, the coefficient K is determined to be “−2”.

  If the coefficient K is determined in accordance with the rules described above, then, in S107 of FIG. 9, the compensation coefficient Tcon is determined by multiplying the determined coefficient K by the read inter-member friction torque Tfric. The If the determined compensation torque Tcon is realized by the electric power steering 26, a change in the steering reaction force Tre accompanying the generation of the inter-member friction force due to the active steering is suppressed.

  This completes one execution of the compensation torque determination program.

  As is apparent from the above description, in the present embodiment, the computer 82 executes the active steering program shown in FIG. 4 to execute an example of “active steering” in the above item (1). Since 82 executes S33 through S36 in FIG. 5 and the compensation torque determination program shown in FIG. 9, an example of the “steering reaction force control” in any one of the items (1) through (4) is executed. is there.

  Further, in the present embodiment, the portion of the computer 82 that executes the compensation torque determination program shown in FIG. 9 constitutes an example of the “compensation torque determination means” in the item (5). Furthermore, the portion of the computer 82 that executes S106 in FIG. 9 constitutes an example of the “first determining means” in the above item (6) or (7).

  Furthermore, in the present embodiment, the portion of the computer 82 that executes the compensation torque determination program shown in FIG. 9 constitutes an example of the “ninth determination means” in the item (17).

  Next, a second embodiment of the present invention will be described. However, this embodiment is different from the first embodiment only in the content of the compensation torque determination program, and other elements are common, and therefore, common elements are cited using the same reference numerals or names. Therefore, detailed description is omitted, and only the compensation torque determination program will be described in detail.

  In the first embodiment, the combination of the steering speed Vs and the pinion speed Vp is associated with the coefficient K common to them, and finally associated with the compensation torque Tcon.

  On the other hand, in the present embodiment, the component of the compensation torque Tcon is separated into the first partial compensation torque Tcon1 and the second partial compensation torque Tcon2, and the steering speed Vs and the pinion speed Vp are respectively the first partial compensation torque. It is associated with Tcon1 and the second partial compensation torque Tcon2.

  FIG. 11 conceptually shows a content of a compensation torque determination program executed by the computer 82 of the ECU 80 of the vehicle steering system according to the present embodiment in a flowchart. Hereinafter, the compensation torque determination program will be described, but steps common to the compensation torque determination program in the first embodiment will be briefly described.

  In the compensation torque determination program in the present embodiment, S131 to S134 are executed in the same manner as S101 to S104 in FIG.

  Subsequently, in S135, the first partial compensation torque Tcon1 is determined based on the calculated steering speed Vs, for example, according to the relationship represented by the graph in FIG. In the example shown in the graph of FIG. 12, when the absolute value of the steering speed Vs does not exceed the non-zero threshold value Vsth, the first partial compensation torque Tcon1 is determined to be 0. When the absolute value exceeds the threshold value Vsth, the first partial compensation torque Tcon1 is determined to be a setting value that is not zero. In the present embodiment, the set value is equal to the inter-member friction torque Tfric.

  Specifically, when the steering speed Vs exceeds the positive threshold + Vsth, the first partial compensation torque Tcon1 is determined to be a negative set value −Tfric, while the steering speed Vs is a negative threshold − If it falls below Vsth, the first partial compensation torque Tcon1 is determined to be a positive set value + Tfric.

  Thereafter, in S136 of FIG. 11, the second partial compensation torque Tcon2 is determined based on the calculated pinion speed Vp, for example, according to the relationship represented by the graph in FIG. In the example shown in the graph of FIG. 13, when the pinion speed Vp is zero, the second partial compensation torque Tcon2 is determined to be zero, whereas when the pinion speed Vp is not zero, the second part The compensation torque Tcon2 is determined to a non-zero set value. In the present embodiment, the set value is equal to the inter-member friction torque Tfric.

  Specifically, when the pinion speed Vp is larger than 0, the second partial compensation torque Tcon2 is determined to be a positive set value + Tfric, while when the pinion speed Vp is smaller than 0, the second partial compensation torque Tcon2 is determined to be a negative set value -Tfric.

  As is apparent from the above description, in the present embodiment, the maximum absolute value of the first partial compensation torque Tcon1 based on the steering speed Vs and the maximum absolute value of the second partial compensation torque Tcon2 based on the pinion speed Vp. Both values are set to be equal to the inter-member friction torque Tfric.

  Subsequently, in S137 of FIG. 11, the compensation torque Tcon is determined to be equal to the sum of the first and second partial compensation torques Tcon1 and Tcon2 determined as described above. Here, the compensation torque Tcon is determined so as to have the same relationship as the relationship represented by the table in FIG. 10 between the steering speed Vs and the pinion speed Vp.

  This completes one execution of the compensation torque determination program.

  Next, a third embodiment of the present invention will be described. However, since this embodiment has many elements in common with the first and second embodiments, the common elements are referred to by using the same reference numerals or names, and detailed descriptions thereof are omitted, and different elements are used. Only will be described in detail.

  In the first and second embodiments, when determining the compensation torque Tcon, the inter-member friction torque Tfric is handled as a fixed set value. On the other hand, in this embodiment, the inter-member friction torque Tfric is determined as a variable value each time.

  FIG. 14 is a functional block diagram showing the main part of the ECU 80 in the present embodiment. In this ECU 80, an inter-member friction torque determining unit 100 is provided. The inter-member friction torque determining unit 100 determines the inter-member friction torque Tfric based on the steering torque, the assist current flowing through the motor 62 of the electric power steering 26 to generate the assist torque, and the temperature of the steering device. Is done. The temperature of the steering device is detected by a temperature sensor 102 shown in FIG.

  The determined inter-member friction torque Tric is supplied to the compensation torque determination unit 104. In the compensation torque determination unit 104, the compensation torque Tcon is determined in the same manner as in the first and second embodiments, based on the supplied inter-member friction torque Tfric, the steering angle θs, and the pinion angle θp. .

  The determined compensation torque Tcon is supplied to the assist control unit 108 via the low-pass filter 106 (represented by “LPS” in FIG. 14). The supplied compensation torque Tcon is smoothed by removing high-frequency noise by the low-pass filter 106.

  In the assist control unit 108, a phase compensation filter 110 is provided. The phase compensation filter 110 performs phase advance compensation on the compensation torque Tcon and steering torque supplied thereto. A command signal is output from the assist control unit 108, and the command signal is supplied to the assist current determination unit 112. The assist current determination unit 112 determines the reference value Iref of the assist current.

  The determined reference value Iref is supplied to the driver 114. As a result, a current having a value equal to the reference value Iref is supplied to the motor 62 from a power source (not shown). By the energization, the motor 62 generates assist torque for realizing reduction of the steering torque and suppression of the change in the steering reaction force Tre caused by the active steering.

  FIG. 15 is a functional block diagram showing details of the inter-member friction torque determining unit 100. In the inter-member friction torque determining unit 100, the steering torque and the assist current are supplied to the friction torque estimating unit 118.

  In the friction torque estimating unit 118, as conceptually shown in the graph of FIG. 16, the amount of change in the steering torque Ts between immediately before and immediately after the sign of the steering torque Ts is reversed, and the assist current I ( Focusing on the fact that the sum of the change amount and the amount of change in the torque is equivalent to the inter-member friction torque Tfric, the inter-member friction torque Tfric is estimated based on the steering torque Ts and the assist current I. In FIG. 16, “Tspeak” and “Ipeak” represent the steering torque and the assist current immediately before the reversal of the sign of the steering torque Ts, respectively, while “Tslow” and “Ilow” respectively represent the state immediately after the reversal. The steering torque and the assist current are represented.

  As shown in FIG. 15, the inter-member friction torque Tfric estimated by the friction torque estimation unit 118 is output to the outside via the friction torque output unit 120.

  As shown in FIG. 15, the inter-member friction torque determining unit 100 is further provided with a friction torque memory 122 and a friction torque reading unit 124. In the friction torque memory 122, for example, as shown in the graph of FIG. 17, the inter-member friction torque Tfric is stored in advance in association with the temperature of the steering device. The friction torque reading unit 124 reads the inter-member friction torque Tfric corresponding to the detected temperature value from the friction torque memory 122. The read inter-member friction torque Tfric is output to the outside via the friction torque output unit 120.

  As shown in FIG. 15, the inter-member friction torque determining unit 100 is further provided with a memory updating unit 126. The memory update unit 126 is provided for updating data in the friction torque memory 122 with reference to the inter-member friction torque Tfric estimated by the friction torque estimation unit 118.

  FIG. 18 conceptually shows in a flowchart the contents of a friction torque reading program executed by the computer 82 in order to implement the processing of the friction torque reading unit 124 described above.

  When executing this friction torque reading program each time, first, in S181, it is determined whether or not the estimation of the inter-member friction torque Tfric has been completed by the friction torque estimation unit 118 after a series of vehicle travels has started. The If it is assumed that the estimation of the inter-member friction torque Tfric has not yet been completed since it is the initial stage of this series of vehicle travel, the determination is NO.

  In this case, the temperature is detected by the temperature sensor 102 in S182. Subsequently, in S183, based on the detected temperature, the inter-member friction torque Tfric corresponding to the temperature is read from the friction torque memory 122 in accordance with the relationship represented by the graph in FIG.

  Thereafter, in S <b> 184, the read inter-member friction torque Tfric is output to the compensation torque determination unit 104. Thus, one execution of this friction torque reading program is completed.

  If it is assumed that the estimation of the inter-member friction torque by the friction torque estimating unit 118 has been completed while the execution of the friction torque reading program is repeated, the determination in S181 becomes YES, and one time of this friction torque reading program is immediately performed. Execution ends.

  FIG. 19 conceptually shows, in a flowchart, the contents of a friction torque estimation program executed by the computer 82 of the ECU 80 in order to implement the processing of the friction torque estimation unit 118.

  In each execution of this friction torque estimation program, the steering torque Ts is first detected by the steering torque sensor 70 in S151. Next, in S152, the assist current I supplied to the motor 62 is detected using the current sensor 130 shown in FIG.

  Subsequently, in S153, for the detected steering torque Ts, a value immediately before the sign of the steering torque Ts is inverted and a value immediately after it are detected. Similarly, for the detected assist current I, a value immediately before the sign of the steering torque Ts is inverted and a value immediately after it are detected. For each of the steering torque Ts and the assist current I, a difference (hereinafter referred to as “front-rear difference”) between immediately before and after the inversion is calculated, and the inter-member friction torque Tfric is calculated based on the sum of the calculated values. Is estimated.

  Thereafter, in S154, it is determined whether or not the estimation of the inter-member friction torque Tfric has been completed. In the case where the inter-member friction torque Tfric is estimated with a predetermined accuracy because a large amount of data is accumulated with respect to the front-rear difference of the steering torque Ts and the front-rear difference of the assist current I so that the estimation accuracy is ensured. It is determined that the estimation has been completed. Otherwise, it is determined that the estimation has not been completed, and further data accumulation is performed.

  If it is assumed that the estimation is not completed this time, the determination in S154 becomes NO, and one execution of this friction torque estimation program is immediately terminated.

  On the other hand, this time, assuming that the estimation is completed, the determination in S154 is YES, and the execution of S155 and S156 causes the data in the friction torque memory 122 to be equal to the estimated inter-member friction torque Tfric. Configured. In the present embodiment, the friction torque between members Tfric is associated with the temperature in the friction torque memory 122. Therefore, in S155, the temperature of the steering device is detected, and in S156, the inter-member friction torque Tfric corresponding to the detected temperature is updated to be equal to the current estimated value.

  Thereafter, in S157, the estimated inter-member friction torque Tfric is output to the compensation torque determination unit 104.

  This completes one execution of the friction torque estimation program.

  As is clear from the above description, in the present embodiment, the portion of the computer 82 that executes S151 through S153 in FIG. 19 constitutes an example of the “second determining means” in the above item (8). It is. Further, the portion of the computer 82 that executes the friction torque reading program shown in FIG. 18 constitutes an example of the “third determining means” in the item (9).

  Next, a fourth embodiment of the present invention will be described. However, since this embodiment has many elements in common with the second embodiment, the common elements are cited using the same reference numerals or names, and detailed description is omitted, and only different elements are cited. This will be described in detail.

  In the present embodiment, as shown in FIG. 20, in order to determine whether the steering wheel 14 is in the steered state or in the steered state, it is compared with the steering speed Vs, as in the second embodiment. As the power threshold, a positive threshold + Vsth and a negative threshold −Vsth, both of which are not 0, are used. That is, whether the steering wheel 14 is in the steering state (steady state) or in the steered state (transient state) is stably determined by using the dead zone based on the steering speed Vs.

  Therefore, according to the present embodiment, as shown in the left part of FIG. 20, even if the steering wheel 14 is operated to rotate and vibrate by the driver even though the steering wheel is maintained, it is based on the steering speed Vs. The first partial compensation torque Tcon1 determined in this way does not change with time, and the steering feeling does not deteriorate due to the execution of the steering reaction force control.

  On the other hand, as shown in FIG. 21, when 0 is used as the threshold value to be compared with the steering speed Vs, the first partial compensation torque Tcon1 is obtained when the steering wheel 14 is caused to rotate and vibrate in the steered state. Tends to fluctuate with time, and the steering feeling deteriorates.

  In this embodiment, as shown in FIG. 22, in order to determine whether the pinion shaft 32 is in a stopped state or in a rotating state, the threshold value to be compared with the pinion speed Vp is all 0. A positive threshold + Vpth and a negative threshold −Vpth are used. That is, whether the pinion shaft 32 is in a stopped state (steady state) or in a rotating state (transient state) is stably determined based on the pinion speed Vp by using the dead zone.

  When the steering wheel 14 is rotated and vibrated in the steering-holding state, the steering speed Vs responds sensitively, but the pinion shaft 32 does not respond so sensitively. Therefore, the pinion speed Vp is as high as the steering speed Vs. Does not respond sensitively.

  Nevertheless, if the dead band width set for the steering speed Vs is narrower than the dead band width set for the pinion speed Vp, whether or not the steering wheel 14 is in the steering-holding state. The result of the determination is sensitive to the change in the steering speed Vs. As a result, the first partial compensation torque Tcon1 is also sensitively sensitive and the steering feeling is deteriorated.

  Therefore, in this embodiment, the width of the dead zone set for the steering speed Vs is wider than the width of the dead zone set for the pinion speed Vp.

  FIG. 23 shows a modification of the present embodiment. In this modification, the second partial compensation torque Tcon2 continuously changes with respect to the pinion speed Vp within the dead zone set with respect to the pinion speed Vp. On the other hand, in FIG. 22, the second partial compensation torque Tcon2 discontinuously changes with respect to the pinion speed Vp within the dead zone.

  In this modification, the second partial compensation torque Tcon2 is more dependent on the pinion speed Vp in the dead zone than in the case shown in FIG. However, according to this modification, the change in the second partial compensation torque Tcon2 when the pinion speed Vp leaves the dead zone or enters the dead zone is more relaxed than the case shown in FIG.

  As is clear from the above description, in the present embodiment, the threshold value Vsth shown in FIG. 20 constitutes an example of the “first threshold value” in the item (10), and the threshold value shown in FIG. Vpth constitutes an example of the “second threshold value” in the same term.

  Furthermore, in the present embodiment, the first partial compensation torque Tcon1 is determined by comparing the steering speed Vs and the threshold value Vsth by executing the compensation torque determination program shown in FIG. It is an example of “first determination”, and determining the second partial compensation torque Tcon2 by comparing the pinion speed Vp and the threshold value Vpth constitutes an example of “second determination” in the same term. .

  Further, in the present embodiment, the portion of the computer 82 that determines S2 in FIG. 11 and determines the second partial compensation torque Tcon2 according to the relationship shown in FIG. 23 is the “fourth determination means” in the item (11). It constitutes an example.

  Next, a fifth embodiment of the present invention will be described. However, since this embodiment has many elements in common with the fourth embodiment, the common elements are cited using the same reference numerals or names, and detailed description thereof is omitted, and only different elements are cited. This will be described in detail.

  As shown in FIG. 24, in the present embodiment, a first threshold value Vsth1 and a larger second threshold value Vsth2 are set on both the positive side and the negative side of the steering speed Vs. Furthermore, the region defined by the positive first threshold value + Vsth1 and the negative first threshold value −Vsth1 corresponds to the dead zone set for the steering speed Vs in the fourth embodiment.

  By the way, as shown in FIG. 25, when the width of the dead zone is expanded to a region defined by the positive second threshold value + Vsth2 and the negative second threshold value -Vsth2, the steering speed Vs is centered on zero. , The tendency that the first partial compensation torque Tcon1 is stabilized increases. However, when the steering speed Vs oscillates around the second threshold value Vsth2, the first partial compensation torque Tcon1 tends to become unstable.

  On the other hand, in the present embodiment, as shown in FIG. 24, the first partial compensation torque Tcon1 is maintained at 0 between 0 and the first threshold value Vsth1, but the first threshold value is set. Between Vsth1 and the second threshold value Vsth2, the first partial compensation torque Tcon1 is continuously changed with respect to the steering speed Vs.

  Therefore, according to the present embodiment, the first partial compensation torque Tcon1 is not only for the case where the steering speed Vs vibrates around 0 but also for the case where the steering speed Vs vibrates around the second threshold value Vsth2. Is stabilized.

  FIG. 26 shows a modification of the present embodiment. In this modification, a hysteresis region between the steering speed Vs and the first partial compensation torque Tcon1 is set between the first threshold value Vsth1 and the second threshold value Vsth2.

  When the steering speed Vs is changed to approach 0 in this hysteresis region, the first partial compensation torque Tcon1 is kept constant in the hysteresis region, and the first partial compensation torque Tcon1 is not changed until after passing through the hysteresis region. Can be changed.

  On the other hand, when the steering speed Vs is changed in a direction away from 0 in this hysteresis region, the first partial compensation torque Tcon1 is kept constant in the hysteresis region, and only after passing through the hysteresis region, the first partial compensation torque. Tcon1 is changed.

  Therefore, according to this modification, even when the steering speed Vs vibrates between the first threshold value Vsth1 and the second threshold value Vsth2, the first partial compensation torque Tcon1 has the above-described hysteresis. It does not change as strongly as it does when it does not exist, thus improving the steering feeling.

  As is apparent from the above description, in this embodiment, the part of the computer 82 that determines the first partial compensation torque Tcon1 in S135 in FIG. 11 according to the relationship shown in FIG. It constitutes an example of “fifth determining means”.

  Further, in the present embodiment, the part of the computer 82 that determines the first partial compensation torque Tcon1 according to the relationship shown in FIG. 26 in S135 in FIG. 11 is the “sixth determining means” in the above (13). It constitutes an example.

  Next, a sixth embodiment of the present invention will be described. However, since the present invention has many elements in common with the first to fifth embodiments, the common elements are referred to using the same reference numerals or names, and detailed description thereof is omitted.

  In the first to fifth embodiments, as shown in FIG. 8, when active steering is started in a completely steered state and when it is started in a steered state opposite to the active steering. The compensation torque Tcon is determined on the assumption that any one of the above is true.

  On the other hand, in the present embodiment, even when active steering is started in a state intermediate between the complete steered state and the reverse steered state, the compensation torque Tcon is obtained with high accuracy. It has become.

  In order to achieve this object, in this embodiment, in addition to some programs executed by the computer 82 in the first to fifth embodiments, correction values conceptually shown in the flowcharts in FIGS. 27 and 28, respectively. A calculation program and a compensation torque correction program are executed by the computer 82.

  FIG. 29 is a graph showing an example of temporal transition for each of the steering angle θs and the pinion angle θp. In this example, at the time t1, the steering angle θs and the pinion angle θp are both stopped. Thereafter, while the pinion angle θp is kept constant, the steering angle θs increases, and at time t2, active steering is started, and the pinion angle θp increases.

  In FIG. 30, the relationship between the pinion angle θp and the steering torque Ts is represented by a graph similar to the graph representing the relationship between the steering angle θs and the steering reaction force Tre shown in FIG. In this graph, it is indicated by a point P1 that the steering angle θs and the pinion angle θp are in a steady state at the time t1 and the steering wheel 14 is in a completely steered state.

  On the other hand, immediately before the time t2, that is, immediately before the start of the active steering, the fact that the steering torque Ts is increased with respect to the steering torque Ts in the complete steered state is represented by a portion indicated by a point P2. Has been. At time t2, when active steering is started, the pinion angle θp changes and the steering torque Ts also changes.

  If active steering is started at time t1, the first partial compensation torque Tcon1 at that time should be determined so as to coincide with the inter-member friction torque Tfric. However, even when active steering is started at time t2, if the first partial compensation torque Tcon1 is determined to coincide with the inter-member friction torque Tfric and realized by the electric power steering 26, the assist torque becomes excessive. Will be generated.

  This is because, as shown in FIG. 30, the steering torque Ts has already been increased by ΔTc at time t2, and the assist torque added to compensate for the inter-member friction torque Tfric during active steering is shown in FIG. This is because Tcon1 and a value obtained by subtracting ΔTc from the inter-member friction torque Tfric is sufficient.

  Against the background described above, when each correction value calculation program shown in FIG. 27 is executed each time, first, both flag 1 and flag 2 are set to 0 in S201. Further, both the correction value ΔTc and the immediately preceding steering torque Ts (n−1) are set to zero.

  Next, in S202, it is determined whether or not the flag 1 is 0. Since this time is 0, the determination is YES, and the current values of the steering speed Vs and the pinion speed Vp are detected in S203. Subsequently, in S204, the absolute value of the detected value of the steering speed Vs is smaller than the threshold A (sufficiently close to 0), and the absolute value of the detected value of the pinion speed Vp is smaller than the threshold B (0 Or close enough).

  If it is assumed that the two conditions are both established this time, the determination is YES, and in S205, the current value of the steering torque Ts is detected, and the immediately preceding steering torque ts (n-1) is equal to the detected value. Is set. Thereafter, in S206, the flag 1 is set to 1. Subsequently, the process returns to S202.

  Since flag 1 is not 0 this time, the determination in S202 is NO, and it is determined in S207 whether or not active steering is started. If it is assumed that it has not started this time, the determination is no, and the current value of the pinion speed Vp is detected in S208. Subsequently, in S209, it is determined whether or not the absolute value of the detected value is larger than the threshold value D. If it is assumed that the value is large this time, the determination is YES, and one execution of the correction value calculation program ends. In contrast, if it is assumed that the absolute value of the detected value of the pinion speed Vp is not greater than the threshold value D this time, the determination in S209 is NO and the process returns to S202.

  If the active steering is started and the determination of S207 is YES while the execution of S202 and S207 to S209 is repeated, the process proceeds to S210. In S210, it is determined whether or not the flag 2 is 0. Since this time is 0, the determination is YES, and the flag 2 is set to 1 in S211. Thereafter, in S212, the current value of the pinion speed Vp is detected. Subsequently, in S213, it is determined whether or not the absolute value of the detected value is larger than the threshold value C (the pinion shaft 32 starts to rotate). The

  If it is assumed that the absolute value of the detected value of the pinion speed Vp is not greater than the threshold value C this time, the determination in S213 is NO, S214 and S215 are skipped, and the process returns to S202. On the other hand, this time, if it is assumed that the absolute value of the detected value of the pinion speed Vp is larger than the threshold value C, the determination in S213 is YES, and the process proceeds to S214.

  In S214, the current value of the steering torque Ts is detected, and the current steering torque Ts (n) is set to be equal to the detected value. Subsequently, in S215, a correction value ΔTc for correcting the compensation torque Tcon is calculated by subtracting the immediately preceding steering torque Ts (n−1) from the current steering torque Ts (n). The calculated correction value ΔTc is stored in the RAM 88. Thereafter, the process returns to 202.

  On the other hand, when the compensation torque correction program shown in FIG. 28 is executed each time, first, the latest value of the correction value ΔTc is read from the RAM 88 in S231. Next, in S232, the compensation torque Tcon acquired in the same manner as in the first to fifth embodiments is read from the ROM 86 or the RAM 88.

  Subsequently, in S233, the compensation torque Tcon is corrected by subtracting the read correction value ΔTc from the read compensation torque Tcon. Thereafter, in S234, the corrected compensation torque Tcon is output to the power assist control program or the assist control unit 108.

  This completes one execution of the compensation torque correction program.

  As is apparent from the above description, in the present embodiment, the correction value calculation program shown in FIG. 27, the compensation torque correction program shown in FIG. 28, and the compensation torque determination shown in FIG. The part that executes the program constitutes an example of the “seventh determining means” in the above section (14).

  Next, a seventh embodiment of the present invention will be described. However, since this embodiment has many elements in common with the sixth embodiment, and only the elements related to the compensation torque correction program are different, the common elements are cited using the same reference numerals or names. Therefore, detailed description will be omitted, and only different elements will be described in detail.

  FIG. 31 conceptually shows in a flowchart the contents of a compensation torque correction program executed by the computer 82 of the ECU 80 in the present embodiment.

  When this compensation torque correction program is executed each time, first, the elapsed time t is set to 0 in S251. Next, in S252, the correction value ΔTc is read from the RAM 88. Subsequently, in S253, it is determined whether or not the absolute value of the read correction value ΔTc is larger than the threshold value E (substantially not 0). If it is assumed that it is larger than the threshold value E this time, the determination is YES, and the flow proceeds to S254.

  In S254, the elapsed time T is increased by a minute increment Δt (execution cycle), and then the read correction value ΔTc is attenuated based on the time constant T in S255. For example, as shown in the graph of FIG. 32, this attenuation is performed so that it gradually decreases with the elapsed time t and eventually becomes zero.

  Subsequently, in S256 of FIG. 31, the compensation torque Tcon obtained in the same manner as in the first to sixth embodiments is read from the ROM 86 or the RAM 88. Thereafter, in S257, the compensation torque Tcon is corrected by subtracting the attenuation value of the correction value ΔTc from the read compensation torque Tcon. Unlike the sixth embodiment, the corrected compensation torque Tcon is changed so as to be gradually restored to the value before correction as time elapses.

  Subsequently, in S <b> 258, the corrected compensation torque Tcon is output to the power assist control program or the assist control unit 108.

  This completes one execution of the compensation torque correction program.

  Next, an eighth embodiment of the present invention will be described. However, since the present embodiment has many elements in common with the first to seventh embodiments, the common elements are referred to by using the same reference numerals or names, and detailed descriptions thereof are omitted and are different. Only the elements are described in detail.

  In the first to seventh embodiments, the inter-member friction torque Tfric is handled as a fixed value. The inter-member friction torque Tfric is set on the assumption that the hysteresis width shown in FIG. 7 does not change.

  On the other hand, in the present embodiment, focusing on the fact that the inter-member friction torque Tfric changes depending on the normal force between the contact tooth surfaces in the rack and pinion mechanism 38, for example, the inter-member friction torque Tfric is accurately determined. A friction torque correction program is executed by the computer 82 of the ECU 80 in order to improve the steering feeling by accurately compensating for the change in the steering reaction force Tre caused by the active steering.

  FIG. 33 conceptually shows the contents of the friction torque correction program in a flowchart. When the friction torque correction program is executed each time, first, a basic value Tfric0 of the inter-member friction torque Tfric is read from the ROM 86 in S301. Next, in S302, the axial force F acting on the rack shaft 30 is acquired based on the detected value of the steering torque Ts and the detected value of the assist current I supplied to the motor 62 of the electric power steering 26.

  Subsequently, in S303, a coefficient G corresponding to the acquired axial force F is determined according to a preset relationship between the axial force F and the coefficient G. The coefficient G is a coefficient to be multiplied to correct the basic value Tfric0. The relationship set between the coefficient G and the axial force F is, for example, a relationship in which the coefficient G increases from 1 as the axial force F increases. In FIG. 34, an example of the relationship is represented by a graph.

  Thereafter, in S304 of FIG. 33, the determined coefficient G is multiplied by the basic value Tfric0, whereby the inter-member friction torque Tfric is corrected. The corrected inter-member friction torque Tfric is stored in the RAM 88 in preparation for the next determination of the compensation torque Tcon.

  Thus, one execution of this friction torque correction program is completed.

  As is apparent from the above description, in the present embodiment, the portion of the computer 82 that executes the friction torque correction program shown in FIG. 33 and the compensation torque determination program shown in FIG. 9 or FIG. This constitutes one example of the “eighth determining means” in item 16).

  Next, a ninth embodiment of the present invention will be described. However, since this embodiment has many elements in common with the second embodiment, the common elements are cited using the same reference numerals or names, and detailed description is omitted, and only different elements are cited. This will be described in detail.

  In the second embodiment, as shown in FIGS. 12 and 13, the absolute value of the first partial compensation torque Tcon1 based on the steering speed Vs and the absolute value of the second partial compensation torque Tcon2 based on the pinion speed Vp. Are set to be equal to the inter-member friction torque Tfric.

  On the other hand, in the present embodiment, as shown in FIG. 35, the first partial compensation torque Tcon1 is changed so as to have an inclination with respect to the steering speed Vs and hysteresis. Furthermore, in the present embodiment, the first partial compensation torque Tcon1 determined by the execution of S135 in FIG. 11 in the second embodiment is corrected by multiplying it by the coefficient H. As a result, the maximum absolute value of the first partial compensation torque Tcon1 is changed according to the value of the coefficient H multiplied by the inter-member friction torque Tfric.

  Therefore, when the coefficient H is smaller than 1, the first partial compensation torque Tcon1 is reduced as compared with the case where the coefficient H is 1. For example, for the maximum absolute value of the first partial compensation torque Tcon1, the second partial The absolute value of the compensation torque Tcon2 is smaller than the maximum value (equal to the inter-member friction torque Tfric). The decrease in the first partial compensation torque Tcon1 means that a portion of the assist torque that contributes to the steering speed Vs is smaller than a portion that contributes to the pinion speed Vp. As a result, during active steering, the steering reaction force Tre becomes less sensitive to the steering speed Vs than the pinion speed Vp, and the steering feeling becomes heavier, which increases the driver's sense of security. means.

  Furthermore, in the present embodiment, when the running stability of the vehicle is lower than normal, auto counter steering is performed by active steering, and when the auto counter steering is executed, the driver can feel at ease. In order to improve, the coefficient H is decreased to a value smaller than 1.

  In order to execute these processes, in the present embodiment, a compensation torque correction program is executed by the computer 82 of the ECU 80. The compensation torque correction program is executed to selectively correct the first partial compensation torque Tcon1 determined in S135 in FIG.

  FIG. 36 conceptually shows the contents of the compensation torque correction program in a flowchart. When executing this compensation torque correction program each time, first, in S331, the vehicle state quantity is detected in the same manner as in S1 of FIG. Next, in S332, as in S2 of FIG. 4, it is determined whether or not the vehicle stability is lower than normal.

  If it is assumed that the vehicle stability is not lower than usual this time, the determination in S332 is NO, and in S333, the coefficient H is set to a value equal to the value H1 (= 1). Subsequently, in S334, the first partial compensation torque Tcon1 determined by the execution of S135 of FIG. 11 and stored in the RAM 88 is read out.

  Thereafter, in S335, the first partial compensation torque Tcon1 is corrected by multiplying the read first partial compensation torque Tcon1 by the set coefficient H. Since the coefficient H is 1 this time, the correction for the original first partial compensation torque Tcon1 is not substantially performed.

  Subsequently, in S336, the corrected first partial compensation torque Tcon1 is output in preparation for the next execution of S137 in FIG. Specifically, the corrected first partial compensation torque Tcon1 is stored in the RAM 88.

  This completes one execution of the compensation torque correction program.

  On the other hand, if it is assumed that the vehicle stability has decreased this time, the determination in S332 is YES, and in S337, it is determined that it is necessary to improve the driver's sense of security this time.

  Subsequently, in S338, the coefficient H is set to be equal to a value H2 that is smaller than the value H1. Thereafter, in S334, the original first partial compensation torque Tcon1 is read from the RAM 88.

  Subsequently, in S335, the read first partial compensation torque Tcon1 is multiplied by the set coefficient H, thereby correcting the original first partial compensation torque Tcon1. Since the coefficient H is smaller than 1 this time, a value smaller than the original first partial compensation torque Tcon1 is set as the corrected first partial compensation torque Tcon1.

  Thereafter, in S336, the corrected first partial compensation torque Tcon1 is output in preparation for the next execution of S137 in FIG. Specifically, the corrected first partial compensation torque Tcon1 is stored in the RAM 88.

  This completes one execution of the compensation torque correction program.

  As is apparent from the above description, in the present embodiment, the portion of the computer 82 that executes the compensation torque correction program shown in FIG. 36 and the compensation torque determination program shown in FIG. This constitutes an example of the “ninth determining means” in item 19).

  Next, a tenth embodiment of the present invention will be described. However, since this embodiment has many elements in common with the first embodiment, the common elements are cited using the same reference numerals or names, and detailed description thereof is omitted, and only different elements are cited. This will be described in detail.

  As shown in FIG. 7, if the steering reaction force control described above is not executed, a first change ΔT1 based on the frictional force between the members and a second change based on the frictional force between the tire and the road surface due to active steering are applied to the steering reaction force Tre. A change ΔT2 occurs.

  In order to suppress the occurrence of the second change ΔT2, it is necessary to detect the gradient between the steering angle θs and the steering reaction force Tre. As shown in FIG. 37, this gradient corresponds to the gradient between the turning angle θw of the wheel 20 (generated by active steering) and the axial force F acting on the rack shaft 30.

  Therefore, if the turning angle θw and the axial force F are determined, the gradients thereof are determined, and consequently the gradient between the steering angle θs and the steering reaction force Tre is also determined. If this gradient is used, the assist torque Ta to be generated in order to suppress the occurrence of the second change ΔT2 is also found. This assist torque Ta (more precisely, the change amount ΔTa of the assist torque Ta during active steering) is obtained by setting the assist ratio γ to the turning angle θw (more precisely, the change amount Δθw of the turning angle θw during active steering). It can be calculated by multiplying.

  On the other hand, the axial force F acting on the rack shaft 30 is the sum of the driver's steering torque Ts and the assist torque Ta by the motor 62 of the electric power steering 26. Therefore, if the steering torque Ts and the assist current I supplied to the motor 62 are known, the axial force F acting on the rack shaft 30 can be detected.

  Further, the turning angle θw can be detected by using a rack position sensor 134 (see FIG. 3) that detects the linear displacement position of the rack shaft 30.

  However, the axial force F and the turning angle θw can be detected with a relatively high accuracy when the physical quantities do not fluctuate because the steering wheel 14 is in the steered state, but in the steered state. , Noise is likely to be mixed into the detected values of these physical quantities. Therefore, in the steered state, it is desirable to estimate the road surface μ that affects the friction force between the tire and the road surface, and to determine the assist ratio γ from the estimated value.

  In the present embodiment, the third partial compensation torque determination program is executed by the computer 82 of the ECU 80 in order to determine the assist torque ΔTa to be changed to suppress the occurrence of the second change ΔT2 as the third partial compensation torque Tcon3. Is done.

  FIG. 38 conceptually shows the contents of the third partial compensation torque determination program in a flowchart.

  When the third partial compensation torque determination program is executed each time, first, in S351, it is determined based on the detected value of the steering speed θs whether or not the steering wheel 14 is in the steered state. This time, if it is assumed that the steering wheel is maintained, the determination is YES, and the axial force F acting on the rack shaft 30 is detected in S352 as described above. Subsequently, in S353, the turning angle θw of the wheel 20 is detected as described above.

  Thereafter, in S354, based on the detected axial force F and the turning angle θw, the current assist ratio γ is determined according to a rule predetermined between them and the assist ratio γ.

  Subsequently, in S355, a change amount Δθw of the turning angle θw resulting from the current active steering is determined. Thereafter, in S356, the change amount ΔTa of the assist torque Ta is determined as the product of the determined change amount Δθw and the determined assist ratio γ.

  Subsequently, in S357, the third partial compensation torque Tcon3 is determined so as to be equal to the determined change amount ΔTa. Thereafter, in S358, the determined third partial compensation torque Tcon3 is stored in the RAM 88.

  This completes one execution of the third partial compensation torque determination program.

  As described above, it is assumed that the steering wheel 14 is in the steering holding state. However, if the steering wheel 14 is not in the steering holding state, the determination in S351 is NO, and the process proceeds to S359.

  In S359, information for estimating the road surface μ, for example, the slip ratio of the wheel 20 is detected, and the road surface μ is estimated based on the detected information. Thereafter, in S360, based on the estimated road surface μ, the current assist ratio γ is determined according to a rule determined in advance between it and the assist ratio γ. Thereafter, S355 to S358 are executed in the same manner as described above.

  FIG. 39 conceptually shows in a flowchart the contents of a compensation torque determination program executed by the computer 82 of the ECU 80 in the present embodiment. Since this compensation torque determination program has many steps in common with the compensation torque determination program of FIG. 11, only the different steps will be described in detail, and the common steps will be described briefly.

  In each execution of the compensation torque determination program in this embodiment, first, S401 to S406 are executed in the same manner as S131 to S136 in FIG. Next, in S407, the third partial compensation torque Tcon3 determined by the execution of the third partial compensation torque determination program and stored in the RAM 88 is read from the RAM 88.

  Subsequently, in S408, the first partial compensation torque Tcon1 determined in S405, the second partial compensation torque Tcon2 determined in S406, and the read third partial compensation torque Tcon3 are equal to each other. The overall compensation torque Tcon is determined.

  This completes one execution of the compensation torque determination program.

  As is apparent from the above description, in the present embodiment, a portion of the computer 82 that executes the third partial compensation torque determination program shown in FIG. 38 and the compensation torque determination program shown in FIG. This constitutes an example of “tenth determining means” in item 21).

  As described above, some of the embodiments of the present invention have been described in detail with reference to the drawings. However, these are exemplifications, and are based on the knowledge of those skilled in the art including the aspects described in the section of [Disclosure of the Invention]. The present invention can be implemented in other forms with various modifications and improvements.

It is a perspective view which shows the hardware constitutions of the steering apparatus for vehicles according to 1st Embodiment of this invention. FIG. 2 is a partial front sectional view showing the vehicle steering apparatus shown in FIG. 1. 3 is a block diagram showing an electric system of the vehicle steering apparatus shown in FIGS. 1 and 2 and a configuration of an ECU 80. FIG. 4 is a flowchart conceptually showing the contents of an active steering program executed by a computer 82 in FIG. 3. 4 is a flowchart conceptually showing the contents of a power assist control program executed by a computer 82 in FIG. 3. 4 is a flowchart conceptually showing the contents of a pinion angle detection program executed by a computer 82 in FIG. 3. 4 is a graph for explaining steering reaction force control by an ECU 80 shown in FIG. 3. It is another graph for demonstrating the steering reaction force control by ECU80 shown in FIG. It is a flowchart which represents notionally the content of the compensation torque determination program performed by the computer 82 in FIG. FIG. 10 is a diagram representing rules referred to in order to determine a coefficient K in S106 in FIG. 9 in a table format. It is a flowchart which represents notionally the content of the compensation torque determination program performed by the computer 82 of ECU80 of the steering apparatus for vehicles according to 2nd Embodiment of this invention. 12 is a graph for explaining the principle by which the first partial compensation torque Tcon1 is determined in S135 in FIG. 12 is a graph for explaining the principle by which the second partial compensation torque Tcon2 is determined in S136 in FIG. It is a functional block diagram which shows the software structure of ECU80 of the steering apparatus for vehicles according to 3rd Embodiment of this invention. It is a functional block diagram which shows the detail of the friction torque determination part 100 between members in FIG. It is a graph for demonstrating the principle in which the friction torque between members of FIG. 15 detects the friction torque Tflic between members. 16 is a graph showing the relationship between the friction torque between members Tfric stored in the friction torque memory 122 in FIG. 15 and the temperature. 16 is a flowchart conceptually showing the content of a friction torque reading program executed by a computer 82 in order to realize the processing of the friction torque reading unit 124 in FIG. 16 is a flowchart conceptually showing the content of a friction torque estimation program executed by a computer 82 in order to realize the processing of the friction torque estimation unit 118 in FIG. It is a graph for demonstrating the content of the steering reaction force control by the vehicle steering device according to 4th Embodiment of this invention. It is a graph for demonstrating the comparative example for demonstrating the effect of the steering reaction force control demonstrated with reference to FIG. FIG. 21 is a graph for explaining the principle by which the second partial compensation torque Tcon2 is determined in the steering reaction force control described with reference to FIG. FIG. 21 is a graph for explaining the principle by which a second partial compensation torque Tcon2 is determined in a modified example of the steering reaction force control described with reference to FIG. It is a graph for demonstrating the content of the steering reaction force control by the vehicle steering device according to 5th Embodiment of this invention. It is a graph for demonstrating the comparative example for demonstrating the effect of the steering reaction force control demonstrated with reference to FIG. FIG. 25 is a graph for explaining the principle by which a first partial compensation torque Tcon1 is determined in a modified example of the steering reaction force control described with reference to FIG. 24. FIG. It is a flowchart which represents notionally the content of the correction value calculation program performed by the computer 82 of ECU80 in the steering apparatus for vehicles according to 6th Embodiment of this invention. It is a flowchart which represents notionally the content of the compensation torque correction program performed by the computer 82 of ECU80 in the steering device for vehicles according to the said 6th Embodiment. It is a graph for demonstrating the content of the correction value calculation program of FIG. It is another graph for demonstrating the content of the correction value calculation program of FIG. It is a flowchart which represents notionally the content of the compensation torque correction program performed by the computer 82 of ECU80 in the steering device for vehicles according to 7th Embodiment of this invention. Fig. 32 is a graph for explaining the contents of S255 in Fig. 31. It is a flowchart which represents notionally the content of the friction torque correction program performed by the computer 82 of ECU80 in the steering device for vehicles according to 8th Embodiment of this invention. It is a graph for demonstrating the relationship between the coefficient G referred in order to determine the coefficient G in S303 in FIG. 33, and the axial force F which acts on the rack shaft 30. FIG. It is a graph for demonstrating steering reaction force control by the vehicle steering device according to 9th Embodiment of this invention. FIG. 36 is a flowchart conceptually showing the contents of a compensation torque correction program executed by a computer 82 in order to execute steering reaction force control described with reference to FIG. 35. It is a graph for demonstrating the steering reaction force control by the vehicle steering device according to 10th Embodiment of this invention. It is a flowchart which represents notionally the content of the 3rd partial compensation torque determination program performed by the computer 82 in order to perform the steering reaction force control demonstrated with reference to FIG. It is a flowchart which represents notionally the content of the compensation torque determination program performed by the computer 82 in order to perform the steering reaction force control demonstrated with reference to FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 14 Steering wheel 16 Steering shaft 20 Wheel 22 Gear ratio change mechanism 24 Steering mechanism 26 Electric power steering 30 Rack shaft 32 Pinion shaft 42 Motor 46 Reduction gear 80 ECU
82 computer

Claims (23)

A vehicle steering device for steering a vehicle by changing a turning angle of a wheel based on a steering operation of a steering operation member by a driver,
The vehicle steering device superimposes a first change resulting from a change in frictional force inside the vehicle steering device and a second change resulting from a change in frictional force between the tire of the wheel and the road surface. In particular, it has a steering characteristic generated in a steering reaction force acting on the driver from the steering operation member,
A steering mechanism for steering the vehicle by a first movable member;
A ratio changing mechanism for changing a ratio between a steering speed at which a driver operates the steering steering member and a displacement speed of the first movable member by a motor capable of driving the first movable member;
An assist mechanism for applying to the vehicle steering device an assist torque for reducing a steering torque applied by the driver to the steering operation member;
A controller that electrically controls the ratio change mechanism and the assist mechanism, and that performs active steering for changing the turning angle via the ratio change mechanism without depending on the steering operation, and when executing the active steering the vehicle steering system comprising as those of the first change that occurs before Kimisao steering reaction force to perform said steering steering reaction force control to reaction force control via the assist mechanism as is suppressed. In the steering holding state in which the driver holds the steering operation member so that the steering angle at which the driver operates the steering operation member does not substantially change, the steering reaction caused by the execution of the active steering is performed. The vehicle steering apparatus according to claim 1, wherein the steering reaction force control is performed so that the first change in force is suppressed. Wherein the controller, the steering reaction force control based on at least one of the temperature of the steering characteristic and the vehicle steering device of the steering operation member of the operation state and the operation state and the vehicle steering device of the steering mechanism The vehicle steering apparatus according to claim 1 or 2, wherein Before SL controller, prior Symbol the steering vehicle steering apparatus according to any one of claims 1 to 3 performs reaction force control such that the second change is suppressed. Wherein the controller, the steering during execution of the reaction force control, wherein said at least one said steering characteristic temperature and the vehicle steering device of the steering operation member of the operation state and the operation state and the vehicle steering device of the steering mechanism 5. Compensation torque determining means for determining a compensation torque to be generated as an assist torque by the assist mechanism in order to compensate for a change in the steering reaction force caused by the active steering based on The vehicle steering device according to claim 1.   The vehicle steering according to claim 5, wherein the compensation torque determination means includes first determination means for determining the compensation torque based on a relationship between a displacement state of the steering operation member and a displacement state of the first movable member. apparatus.   The first determining means is configured such that the steering operation member substantially stops when the steering operation member and the first movable member are displaced in opposite phases with each other. The vehicle steering apparatus according to claim 6, further comprising means for determining the compensation torque so that the absolute value is larger than when the movable member is displaced.   The steering operation member having a value obtained by synthesizing the steering torque and the assist torque based on a physical quantity related to the steering torque and a physical quantity related to the assist torque generated by the assist mechanism. The vehicle steering apparatus according to any one of claims 5 to 7, further comprising second determining means for determining the compensation torque such that the absolute value increases as the difference between before and after the displacement direction of the motor is reversed increases.   9. The compensation torque determination means according to any one of claims 5 to 8, wherein the compensation torque determination means includes third determination means for determining the compensation torque based on the temperature of the vehicle steering device such that the absolute value increases as the temperature decreases. The steering apparatus for vehicles as described. A first determination in which the controller determines whether or not the driver is in a steered state in which the driver holds the steering operation member in substantially the same state by comparing the steering speed with a first threshold; Performing a second determination to determine whether or not the first movable member is in a stopped state by comparing the displacement speed of the first movable member with a second threshold value;
The first and second threshold values are set such that the sensitivity of the first determination result with respect to the steering speed is lower than the sensitivity of the second determination result with respect to the displacement speed of the first movable member. The vehicle steering apparatus according to claim 5.   The said compensation torque determination means includes the 4th determination means which determines the said compensation torque so that it may have the area | region which changes continuously according to the displacement speed of a said 1st movable member. Vehicle steering system.   The vehicle steering apparatus according to any one of claims 5 to 11, wherein the compensation torque determining means includes fifth determining means for determining the compensation torque so as to have a region that continuously changes in accordance with the steering speed. .   The compensation torque determining means is configured so that the driver holds the steering operation member in substantially the same state so as to maintain the traveling angle of the vehicle, and the driver allows the steering angle to change the traveling angle of the vehicle. When the steering operation member transitions between a steering state in which the operation member is operated so that the steering angle thereof changes, the region has a region that changes with hysteresis with respect to the change in the steering speed. The vehicle steering apparatus according to claim 5, further comprising sixth determining means for determining the compensation torque.   The compensation torque determining means includes seventh determining means for determining the compensation torque based on an amount by which a physical quantity related to the steering torque has changed until the first movable member shifts from a stopped state to a displaced state. The vehicle steering apparatus according to any one of claims 5 to 13. The controller is
Smoothing means for smoothing a plurality of compensation torques sequentially determined by the compensation torque determining means;
The vehicle steering apparatus according to claim 5, further comprising: a control unit that controls the assist mechanism so that the smoothed compensation torque is realized.   Eighth determining means for determining the compensating torque so that the absolute value increases as the operating force of the first movable member increases, based on a physical quantity related to the operating force of the first movable member. The vehicle steering device according to claim 5, comprising:   A ninth determining means for determining the compensation torque as a combined value of a first partial compensation torque based on the steering speed and a second partial compensation torque based on a displacement speed of the first movable member; A vehicle steering apparatus according to any one of claims 5 to 16.   18. The vehicle steering apparatus according to claim 17, wherein the ninth determining means determines the first and second partial compensation torques so that the first partial compensation torque has a tendency to decrease from the second partial compensation torque. .   The ninth determining means determines the first and second partial compensation torques so that a decrease amount of the first partial compensation torque with respect to the second partial compensation torque is changed according to whether or not a predetermined condition is satisfied. The vehicle steering apparatus according to claim 18.   Tenth determining means for determining, based on a physical quantity related to the turning angle during execution of the active steering, the compensation torque so that the absolute value increases according to the turning angle. 20. A vehicle steering apparatus according to any one of claims 5 to 19.   In the tenth determining means, the ratio between the turning angle and the compensation torque during the active steering changes according to the ratio between the turning angle and a physical quantity related to the operating force of the first movable member. The vehicle steering apparatus according to claim 20, wherein the compensation torque is determined as described above.   The ratio changing mechanism is further a second movable member driven by the steering operation member, and a speed reducer provided between the second movable member and the motor, and drives the first movable member. The vehicle steering apparatus according to claim 1, wherein a ratio of a displacement speed of the second movable member and a displacement speed of the first movable member is changed by the motor. further,
A steering angle sensor for detecting a steering angle at which a driver operates the steering operation member;
A motor rotation angle sensor for detecting a rotation angle of the motor, and the controller is configured to control the first movable member based on a steering angle and a motor rotation angle respectively detected by the steering angle sensor and the motor rotation angle sensor. The vehicle steering apparatus according to claim 22, further comprising a displacement amount detecting means for detecting a displacement amount of the vehicle.

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