JPH11321689A - Steering device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steering device for vehicle capable of quickly and securely judging the input side and direction of the steering force transmitted by a steering shaft. SOLUTION: This device is provided with a first resolver 53 for outputting the alternating signal, of which phase is changed in response to a change of the operating side rotating angle of a steering shaft to be elastically and relatively rotated at an operation side and an axis side thereof in response to the torque corresponding to the steering force to be transmitted, and a second resolver 65 for outputting the alternating signal, of which phase is changed in response to a change of the wheel side rotating angle. Direction of the steering force and the steering force input side of the steering shaft are judged on the basis of the stored relation among tendency of increasing or decreasing the output value of both the resolvers 53, 65, largeness of the output value of both the resolvers 53, 65, direction of the steering force, and the steering force input side of the steering shaft at the reference time, and on the basis of tendency and largeness of increasing or decreasing the output value of both the resolvers 53, 65 at the reference time, in which the output value and change ratio of the exciting voltage of both the resolvers 53, 65 become constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering apparatus for a vehicle which can be used for performing control corresponding to a change in steering resistance acting on wheels from a road surface.

[0002]

2. Description of the Related Art In recent years, a control device generates a command signal based on an induction signal sent from a road, a detection signal of a road or surrounding conditions, and the like, and a steering force generated by a steering force generating actuator based on the command signal. The development of a steering device for automatically steering a vehicle has been promoted.

At the time of such automatic steering, a steering force may be added to a vehicle due to disturbances such as unevenness and a cross wind on a traveling road other than the steering force generated by the steering force generating actuator.

Therefore, by detecting values such as the yaw rate and the lateral acceleration of the vehicle corresponding to the change in the steering angle of the vehicle, and controlling the steering force generating actuator according to the detected values, the additional steering force due to the disturbance is obtained. Had to compensate for the effects.

[0005] Further, in such a steering device, in order to cope with an emergency or the like, it is required that the driver can switch from an automatic steering mode to a normal steering mode in which a driver generates a steering force.

In view of this, there is provided means for calculating a deviation between a command steering angle corresponding to a command signal to the actuator and an actual steering angle. When the difference is equal to or larger than a set value, it is determined that the driver is against automatic steering. It is considered to make a judgment and switch from the automatic steering mode to the normal steering mode.

[0007]

In the prior art, the influence of the additional steering force due to disturbance is compensated according to a value corresponding to a change in the steering angle of the vehicle. In other words, after the steering angle actually changes, the additional steering force is offset. Therefore, there is a problem that the compensation is delayed and the behavior of the vehicle becomes unstable due to disturbance.

Further, it has not been possible to determine whether the applied steering force other than the steering force generated by the steering force generating actuator is the additional steering force due to disturbance or the additional steering force by the driver. Therefore, there is a problem that the additional steering force due to the disturbance is erroneously determined as the steering force by the driver, and the automatic steering mode is erroneously switched to the normal steering mode.

On a road surface having a small friction coefficient, such as a frozen road surface, the behavior of the vehicle cannot be controlled if the same steering is performed as on a normal road surface. Therefore, it is difficult to perform automatic steering. However, the prior art has not been able to cope with a situation in which the coefficient of friction of the road surface is reduced during automatic steering.

It is an object of the present invention to provide a vehicle steering device that can solve the above-mentioned problem.

[0011]

SUMMARY OF THE INVENTION The present invention comprises a steering shaft for transmitting a steering force to a wheel, and an operation side and a wheel side of the steering shaft generate torque corresponding to the steering force transmitted by the steering shaft. The present invention is applied to a vehicle which is elastically relatively rotatable accordingly. In the vehicle steering apparatus according to the present invention,
A first resolver that outputs an alternating signal whose phase changes in response to a change in the rotation angle of the steering shaft on the operating side, and a phase that changes in response to a change in the rotation angle of the steering shaft on the wheel side; A second resolver that outputs an alternating signal having the same waveform as the output signal of the first resolver. When the operation side rotation angle of the steering shaft is equal to the wheel side rotation angle, the output signal of the first resolver and the second
The output value and phase of the output signal of the resolver are made equal to each other. The output value of both resolvers, the output value of both resolvers, the magnitude of the output value of both resolvers, and the direction of the steering force when the output value and the rate of change of the excitation voltage of both resolvers become a fixed value. And a storage device for storing the relationship between the input side of the steering force to the steering shaft, means for determining the increase and decrease tendency and magnitude of the output values of both resolvers at the time of reference, and the increase and decrease of the output values of both resolvers and Means for judging the direction of the steering force and the input side of the steering force to the steering shaft based on the result of the determination of the magnitude and the stored relationship. In the above configuration, when a steering force is externally applied to the vehicle based on disturbances such as unevenness or a cross wind on a traveling road, or when a driver applies a steering force during automatic steering, the steering force transmitted from the steering shaft corresponds to the steering force. The torque changes before the actual steering angle changes. Since the operating side and the wheel side of the steering shaft rotate relative to each other due to the torque, the output value and the phase of the first resolver and the output value and the phase of the second resolver are different from each other. At this time, the combination of the increasing and decreasing tendency and the magnitude of the output value of both resolvers at the time of reference is the case where the direction of the steering force is right steering and the input side of the steering force to the steering shaft is the operation side, and the direction of the steering force is Is a left steering and the input side of the steering force to the steering shaft is the operating side; a case where the direction of the steering force is the right steering and the input side of the steering force to the steering shaft is the wheel side; Is different from the case where the steering direction is left steering and the input side of the steering force to the steering shaft is the wheel side. Thus, the relation between the prestored increase / decrease tendency and the magnitude of the output values of the resolvers, the direction of the steering force and the input side of the steering force to the steering shaft, and the increase / decrease tendency and the magnitude of the output values of the resolvers at the reference time , The direction of the steering force and the input side of the steering force to the steering shaft can be determined.

The present invention comprises a steering force generating actuator capable of generating a steering force acting on the operating side of the steering shaft, and a control device for the steering force generating actuator, based on a signal from the control device. A steering mode between an automatic steering mode in which the steering force generated by the steering force generating actuator is transmitted to the wheels via the steering shaft and a normal steering mode in which the steering force generated by the driver is transmitted to the wheels via the steering shaft. Is preferably applied to vehicles that can be switched. Accordingly, during automatic steering, before the steering angle is actually changed by the additional steering force due to disturbance other than the steering force generated by the steering force generation actuator, whether or not the additional steering force is applied is determined. Since the direction of the force can be determined, the influence of the additional steering force can be compensated based on the result of the determination.

In the present invention, a value corresponding to the steering force transmitted by the steering shaft is determined based on the outputs of the resolvers, and is added to the automatic steering mode in addition to the steering force generated by the steering force generating actuator. When the input side of the steering force to the steering shaft is determined, the additional steering force is input to the steering shaft from the operation side, and when the absolute value of the additional steering force is equal to or greater than the set value, the normal steering mode is switched to the normal steering mode. Preferably, a means for switching to the mode is provided. When an additional steering force equal to or greater than the set value is input to the steering shaft from the operating side, it can be considered that the driver has intentionally added the steering force. Therefore, according to this configuration, it is possible to switch to the normal steering mode before the actual steering angle changes only by the driver applying the steering force during the automatic steering. As a result, it is possible to quickly switch from the automatic steering mode to the normal steering mode in an emergency or the like.
In addition, since it is determined whether the steering force applied during the automatic steering is applied by the driver or externally to the vehicle based on disturbance such as unevenness or a cross wind on a traveling path, the vehicle is externally applied to the vehicle. Depending on the added steering force,
It is possible to prevent erroneous switching from the automatic steering mode to the normal steering mode.

In the present invention, a value corresponding to the steering force transmitted by the steering shaft is obtained based on the outputs of the resolvers, and is added to the automatic steering mode in addition to the steering force generated by the steering force generating actuator. The input side of the steering force to the steering shaft is determined, and it is determined whether the direction of the additional steering force input from the wheel side to the steering shaft is the same as the direction of the generated steering force of the steering force generating actuator. When an additional steering force in the same direction as the direction of the steering force generated by the steering force generating actuator is input to the steering shaft from the wheel side and the absolute value of the additional steering force is equal to or greater than the set value, the automatic steering mode is set. It is preferable to provide a means for switching from the normal steering mode to the normal steering mode. When the friction coefficient of the road surface decreases, the steering resistance acting on the wheels decreases, so that an additional steering force in the same direction as the steering force generated by the steering force generating actuator acts on the steering shaft from outside the vehicle. Therefore, by switching from the automatic steering mode to the normal steering mode when the absolute value of the additional steering force is equal to or greater than the set value, the automatic steering can be canceled when the road surface friction coefficient is small.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. The rack and pinion type steering device 1 shown in FIG. 1 transmits a steering force generated by a driver from a steering wheel H to a wheel W via a steering shaft. Also, a brushless motor 50 described later is used.
Is transmitted to the wheels W via the steering shaft.

The steering shaft has an input shaft 2 connected to the steering wheel H and an output shaft 4 connected to the input shaft 2 via a torsion bar 3. The torsion bar 3 is connected to the input shaft 2 via a pin 5 and to the output shaft 4 via a serration 6. A pinion 7 is formed on the output shaft 4, and wheels W are connected to each end of the rack 8 that meshes with the pinion 7. The input shaft 2 is connected to a motor housing 10c via a sleeve 2a and a bearing 9 integrated on the outer periphery.
And is supported by the output shaft 4 via a bush 11. The output shaft 4 is supported by the rack housing 10b via bearings 12 and 13. The rack housing 10b and the motor housing 10c are integrated via a valve housing 10a.

The input shaft 2 is rotated by a steering torque based on a steering force. The rotation of the input shaft 2 is transmitted to a pinion 7 via a torsion bar 3 and an output shaft 4.
Is transmitted to The rotation of the pinion 7 causes the rack 8 to move in the axial direction along the vehicle width direction. The wheel W is steered by the movement of the rack 8. At this time, the input shaft 2 on the operation side of the steering shaft and the output shaft 4 on the wheel side are connected to the torsion bar 3 according to the steering torque corresponding to the steering force transmitted by the steering shaft.
Is elastically twisted, so that it relatively elastically rotates around a coaxial center.

Oil seals 14, 15 are provided between the input / output shafts 2, 4 and the valve housing 10a. Further, a support yoke 16 for supporting the rack 8 is provided, and the support yoke 16 is pressed against the rack 8 by the elastic force of a spring 17.

A hydraulic cylinder (actuator) 18 for generating a steering assist force is provided. The hydraulic cylinder 18 includes a cylinder tube constituted by a rack housing 10 b and a piston 2 integrated with the rack 8.
0, and a first oil chamber 21 and a second oil chamber 22 partitioned by the piston 20.

Each of the oil chambers 21 and 22 is connected to a rotary hydraulic control valve 23 that operates based on a steering force. The control valve 23 controls the hydraulic pressure of the pressure oil supplied from the pump 37 to the hydraulic cylinder 18 to generate a steering assist force.

That is, the control valve 23 is a cylindrical first valve.
The first valve member 24 includes a valve member 24 and a second valve member 25 that is coaxially rotatably inserted into the first valve member 24. The first valve member 24 is inserted into the valve housing 10a so as to be relatively rotatable, and is attached to the output shaft 4 via a pin 26 so as to be rotatable therewith. The second
The valve member 25 is integrally formed on the outer periphery of the input shaft 2 and rotates together with the input shaft 2. Thereby, the first valve member 24 and the second valve member 25 are
When the torsion bar 3 is twisted in accordance with the steering torque transmitted by the steering shaft, the torsion bar 3 elastically rotates relatively. Hydraulic cylinder 1 according to the relative rotation amount
The hydraulic pressure of the pressure oil supplied from the pump 37 to 8 is controlled.

As shown in FIG. 2, the first valve member 2
A plurality of recesses along the axial direction are formed at equal intervals in the circumferential direction on the inner circumference of the fourth member 4 and the outer circumference of the second valve member 25. The first
The valve member-side concave portion includes a right steering concave portion 27 and a left steering concave portion 28 which are located at equal intervals in the circumferential direction. The second valve member side recess is composed of a pressure oil supply recess 29 and a pressure oil discharge recess 30 which are located at equal intervals in the circumferential direction. Each right steering recess 27 and each left steering recess 28 are alternately arranged in the circumferential direction, and each pressure oil supply recess 29 and each pressure oil discharge recess 30 are alternately arranged in the circumferential direction.

Each right steering recess 27 is provided with a first valve member 2.
4 and the first flow passage 31 formed in the valve housing 1
0a from the first port 32 formed in the hydraulic cylinder 1
8 to the first oil chamber 21. Each left steering recess 28 is formed by a second flow path 33 formed in the first valve member 24 and a second port 34 formed in the valve housing 10a.
It communicates with the second oil chamber 22 of the hydraulic cylinder 18. Each pressure oil supply recess 29 communicates with a pump 37 via a third flow path 35 formed in the first valve member 24 and an inlet port 36 formed in the valve housing 10a. Each of the recesses 30 for discharging pressure oil includes a first discharge passage 38 formed in the second valve member 25, a passage 47 between the input shaft 2 and the inner and outer circumferences of the torsion bar 3, and a discharge port 40 formed in the valve housing 10 a. Through the tank 41.

Thus, the oil chambers 21 and 22 of the hydraulic cylinder 18 and the pump 37 are connected to each other through the inter-valve oil passage 42 formed between the inner and outer circumferences of the first valve member 24 and the second valve member 25. Connected. The pump 37 is driven by a motor (not shown). In the inter-valve oil passage 42,
Between the first valve member side recess and the second valve member side recess,
The throttle portions A, B, C, and D whose opening degrees change due to the relative rotation of the two valve members 24 and 25 are provided. Each of the apertures A, B,
The hydraulic pressure acting on the hydraulic cylinder 18 is controlled by changing the opening degrees of C and D according to the steering torque. FIG. 3 shows the hydraulic circuit.

FIG. 2 shows the relative positions of the two valve members 24 and 25 in a straight steering position where steering is not performed. In this state, each pressure oil supply recess 29 and each pressure oil discharge recess 29 are provided. The apertures of the throttle portions A, B, C, and D between 30 and 30 are constant.

When the vehicle is steered to the right from the straight steering position, each right steering recess 27 and each hydraulic oil supply are provided in accordance with the relative rotation of the two valve members 24 and 25 due to the torsion of the torsion bar 3 according to the steering torque. The opening degree of the throttle portion A between the concave portion 29 and the opening degree of the throttle portion B between each left steering concave portion 28 and each pressure oil discharging concave portion 30 are increased, and each left steering concave portion 28 is formed.
The opening degree of the throttle portion C between the pressure oil supply concave portion 29 and the throttle portion D between the right steering concave portion 27 and the pressure oil discharge concave portion 30 becomes smaller. Thereby, pressure oil according to the steering torque is supplied from the pump 37 to the first oil chamber 21,
Oil is recirculated from the second oil chamber 22 to the tank 41, and a steering assisting force to the right of the vehicle acts on the rack 8.

When the vehicle is steered to the left from the straight steering position, the opening of each of the throttle portions A, B, C, and D changes in reverse to the case where the vehicle is steered to the right, so that the steering assist force of the vehicle to the left is reduced. Acts on the rack 8.

As shown in FIG. 1, a three-phase brushless motor 50 is provided as an actuator for generating a steering force. The brushless motor 50 includes a rotor 51 mounted inside the motor housing 10c so as to rotate concentrically with the input shaft 2 via the sleeve 2a, and a stator mounted on the motor housing 10c so as to surround the rotor 51. 52, and a first resolver 53 for detecting the rotation angle of the rotor 51. The first resolver 53 has a rotor 53a integrated with the input shaft 2 via the sleeve 2a, and a stator 53b attached to the motor housing 10c. Since the rotor 51 is integrated with the input shaft 2 on the operating side of the steering shaft, the first resolver 53 has a sinusoidal alternating voltage whose phase changes in response to a change in the rotation angle on the operating side of the steering shaft. Output a signal.

A second resolver 65 for detecting the rotation angle of the output shaft 4 is provided. That is, the second
The resolver 65 has a rotor 65a integrated with the output shaft 4, and a stator 65b attached to the rack housing 10b. Thus, the second resolver 65 outputs a sinusoidal alternating voltage signal whose phase changes in response to a change in the rotation angle of the steering shaft on the wheel side. The output signals of both resolvers 53 and 65 have the same waveform.

The brushless motor 50 including the first resolver 53 and the second resolver 65 are connected to a control device 61. The control device 61 includes a mode changeover switch 62
, The input device 63 and the vehicle speed sensor 70 are connected.

By operating the mode changeover switch 62, it is possible to switch the steering mode of the vehicle between the automatic steering mode and the normal steering mode. In the automatic steering mode, the brushless motor 50 generates a steering force based on a command signal from the control device 61,
The steering force is transmitted to the wheels W via the steering shaft. In the normal steering mode, the steering force generated by the driver is transmitted to the wheels W via the steering shaft.

The input device 63 includes, for example, a beacon signal transmitted from a transmitter provided on a traveling road or a guardrail, a warning signal transmitted from a transmitter provided on another vehicle to notify of a danger of collision, , A guidance signal such as a detection signal of a traveling line on the road is input. When the guidance signal is input from the input device 63 in the automatic steering mode, the control device 61
Outputs a command signal for eliminating a deviation between a target steering angle required for steering the vehicle according to the guidance signal and an actual output steering angle. The brushless motor 50 is driven by the command signal. The steering force generated by the brushless motor 50 is transmitted to the wheels W via the steering shaft, similarly to the steering force generated by the driver in the normal steering mode.

Further, the control device 61 sets the torque transmitted by the steering shaft based on the added steering force as a value corresponding to the added steering force other than the steering force generated by the brushless motor 50 during the automatic steering. Is obtained from the outputs of the first resolver 53 and the second resolver 65. That is, the input shaft 2 and the output shaft 4 elastically rotate relative to the coaxial center when the torsion bar 3 is elastically twisted according to the steering torque. Therefore, the difference between the rotation angle of the input shaft 2 detected by the first resolver 53 and the rotation angle of the output shaft 4 detected by the second resolver 65 corresponds to the torque transmitted by the steering shaft. That is, the first and second resolvers 53 and 65 detect a torque corresponding to the steering force transmitted by the steering shaft. The difference between the detected torque and the torque generated by the brushless motor 50 corresponds to the torque transmitted by the steering shaft based on the additional steering force.

The control device 61 determines the rotation angle of the rotor 51, that is, the rotation angle on the operating side of the steering shaft, in a time series based on the output of the first resolver 53, and determines the rotation angle on the wheel side of the steering shaft based on the output of the second resolver 65. Is obtained in time series. When the operation-side rotation angle of the steering shaft is equal to the wheel-side rotation angle, the first resolver 53
Is equal to the output value of the output signal of the second resolver 65, and the phase of the output signal of the first resolver 53 is equal to the phase of the output signal of the second resolver 65.

A sensor 69 for detecting a reference position for detecting the rotation angle by each of the resolvers 53 and 65 is connected to the control device 61, and the rotation angle is obtained based on the detected reference position. The reference position detecting sensor 69
Is an optical sensor attached to the rack housing 10b so as to detect a mark provided on the rack 8 when the rotation angle of the steering shaft is zero, and outputs a reference position signal when the rotation angle of the steering shaft is zero. It can be configured by a device that outputs to the control device 61.

FIG. 4 is a block diagram showing a control system in the automatic steering mode according to the above configuration. In the control device 61, the deviation between the target steering angle θq of the vehicle and the actual output steering angle θo, and the transfer function C1 Then, the target torque Tq is calculated. The actual output steering angle θo corresponds to the rotation angle of the steering shaft on the wheel side. The target torque Tq
Is a value corresponding to the vehicle speed detected by the vehicle speed sensor 70. The transfer function C1 can be obtained experimentally from the relationship between the deviation between the target steering angle θq and the output steering angle θo and the torque required to compensate for the deviation. A target motor drive current Iq is calculated from a torque obtained by adding a compensation torque Tc, which will be described later, to a deviation between the target torque Tq and the total torque T transmitted by the steering shaft, and a transfer function C2. The transfer function C2 can be C2 = 1 / (Kt × s), where Kt is the torque constant of the brushless motor 50 and s is the Laplace operator. The motor applied power Eq is calculated from the deviation between the target motor drive current Iq and the actual drive current Ia of the brushless motor 50 and the transfer function C3. The transfer function C3 is
Assuming that K1 is a current control proportional gain, K2 is a current control integration gain, τ is a current control integration time constant, and a Laplace operator is s, C3 = K1 + K2 / (τ × s). The motor applied power Eq is applied to the brushless motor 50 via the normally closed contact 49. The drive current Ia of the brushless motor 50 is obtained from the deviation between the motor applied power Eq and the motor output power Ea and the transfer function C4. The transfer function C4 is C4 = 1 / (L × s + L) where L is the inductance of the brushless motor 50, R is the internal resistance of the brushless motor 50, and the Laplace operator is s.
R). The motor output power E
a is determined from the output shaft rotation speed of the brushless motor 50, that is, the rotational angular velocity ωi of the steering shaft on the steering wheel H side, and the transfer function C5. The transfer function C5 corresponds to the induced voltage constant of the brushless motor 50. The output torque Ta of the brushless motor 50 is obtained from the drive current Ia and the transfer function C6.
The transfer function C6 corresponds to the torque constant of the brushless motor 50. From the sum of the output torque Ta of the brushless motor 50 and the steering torque Th added by the driver and the transfer function C7, the output shaft rotation speed of the brushless motor 50, that is, the rotational angular velocity of the steering shaft on the steering wheel H side. ωi is obtained. The transfer function C7 represents the inertia on the operating side of the steering device as I
It is possible to obtain C7 = 1 / (Ii × s + Ci), where i is the viscosity resistance on the operation side and Ci is the Laplace operator. The output shaft rotation speed ω of the brushless motor 50
The integral value of i becomes the rotation angle θi of the steering shaft on the steering wheel H side. From the deviation between the rotation angle θi of the steering shaft on the steering wheel H side and the rotation angle θo on the wheel side, and the transfer function C8,
The total torque T transmitted by the steering shaft is determined. The transfer function C8 corresponds to the torsion spring constant of the torsion bar 3. From the total torque T transmitted by the steering shaft and the transfer function C9, the torque Tv corresponding to the output of the steering assist force generating hydraulic cylinder 18 is obtained.
Is found. The transfer function C9 is determined by the hydraulic cylinder 18
Is obtained from the hydraulic control characteristics of the control oil by the control valve 23 of the pressure oil supplied to the control valve. From the sum of the output-corresponding torque Tv of the hydraulic cylinder 18 and the disturbance torque Td corresponding to the steering force externally applied to the vehicle, and the transfer function C10, the rotational angular velocity ωo of the steering shaft on the wheel side is obtained.
The transfer function C10 is C7 = 1 / (Io, where Io is the inertia on the output shaft 4 side of the steering device, Co is the viscous resistance on the output shaft 4 side, and s is the Laplace operator.
× s + Co). The integral value of the rotational angular velocity ωo on the wheel side of the steering shaft is
The rotation angle θo on the wheel side of the steering shaft is obtained.

The storage device 61 built in the control device 61
The control program is stored in a. As a part of the program, the output value of both resolvers 53 and 65 at a certain reference time based on the time when the output value and the rate of change of the excitation voltage of both resolvers 53 and 65 become a certain value, The relationship between the magnitudes of the output values of the resolvers 53 and 65, the direction of the steering force, and the input side of the steering force to the steering shaft is stored. At that time, both resolvers 5 are used as described later.
3, 65 output value increase / decrease tendency and the judgment result of the magnitude,
There is no particular limitation as long as the direction of the steering force and the input side of the steering force to the steering shaft can be determined based on the stored relationship. For example, the time when a certain time has elapsed from the time when the output values of the excitation voltages of both resolvers 53 and 65 become the minimum value (change rate is zero) is set as the reference time.

In this embodiment, the direction of the torque generated on the steering shaft by the action of the steering force is different from the direction of the torque transmitted by the steering shaft when the steering force for right steering is applied from the operating side of the steering shaft. When they match, the direction of the steering force is considered to be the right direction, and when the direction of the torque transmitted by the steering shaft when the steering force for left steering is applied from the operating side of the steering shaft, The direction of the steering force is assumed to be left.

5A to 5D, the relationship between the output value of the first resolver 53 and time is indicated by a solid line, and the relationship between the output value of the second resolver 65 and time is indicated by a broken line. FIG. 5A illustrates a case where the direction of the steering force is the right direction and the input side of the steering force is the operation side of the steering shaft.
FIG. 5B shows a case where the direction of the steering force is the left direction and the input side of the steering force is the operation side of the steering shaft, and FIG. 5C shows a case where the direction of the steering force is the right direction. FIG. 5D shows the case where the steering force input side is the left side and the steering force input side is the steering shaft wheel side. Show.

In (1) to (4) of FIG. 5, the first resolver 53 at a first measurement time point t1 after a lapse of a certain time from when the output value and the rate of change of the excitation voltage of both resolvers 53 and 65 become a certain value. Is the output value of a1, the output value of the second resolver 65 is b1, and the first resolver 5 at the second measurement time (reference time) t2 after a certain time has elapsed from the first measurement time t1.
Assuming that the output value of No. 3 is a2 and the output value of the second resolver 65 is b2, the output value of the first resolver 53 tends to increase if a2-a1> 0, and tends to decrease if a2-a1 <0. The output value of the second resolver 65 has an increasing tendency if b2−b1> 0, and has a decreasing tendency if b2−b1 <0, and the output value of both resolvers 53 and 65 is a2
If −b2> 0, the output value of the first resolver 53 is larger than the output value of the second resolver 65, and if a2−b2 <0, the output value of the first resolver 53 is larger than the output value of the second resolver 65. Is also small.

FIG. 6 shows the tendency of the output values of the first resolver 53 and the second resolver 65 to increase and decrease, the magnitude of the steering force, the direction of the steering force, and the input side of the steering force to the steering shaft. Show the relationship.

The control device 61 judges the increasing and decreasing tendency and the magnitude of the output values of both resolvers 53 and 65 at the time of the reference, and based on the judgment result and the stored relationship, the direction of the steering force and the direction to the steering shaft are determined. Is determined as the input side of the steering force. That is, a2-a1 <0, b2-b1
If <0, a2-b2 <0, it is determined that the direction of the steering force is rightward and that the input side of the steering force is the operation side of the steering shaft. a2-a1> 0, b2-b
When 1> 0 and a2−b2> 0, it is determined that the direction of the steering force is the left direction and the input side of the steering force is the operation side of the steering shaft. a2-a1 <0, b2-
If b1 <0, a2-b2> 0, it is determined that the direction of the steering force is rightward and the input side of the steering force is the wheel side of the steering shaft. a2-a1> 0, b2
When −b1> 0 and a2−b2 <0, it is determined that the direction of the steering force is leftward and the input side of the steering force is the wheel side of the steering shaft.

The flowchart of FIG.
1 shows a control procedure for switching the steering mode according to No. 1.

The control device 61 first determines whether or not the current time is in the automatic steering mode (step 1). In the automatic steering mode, the automatic steering is performed by driving the brushless motor 50 (step 2).

In the automatic steering mode, the input side of the steering shaft other than the steering force generated by the brushless motor 50 to the steering shaft is determined. That is, as described above, a2-a1 <0, b2-b1 <0, a2-b
2 <0 or a2-a1> 0, b2-b1> 0,
If a2−b2> 0, the additional steering force is determined to be the driver generated steering force added from the operating side of the steering shaft, and a2−a1 <0, b2−b1
<0, a2-b2> 0 or a2-a1> 0, b
If 2-b1> 0 and a2-b2 <0, it is determined that the additional steering force is a disturbance from the outside of the vehicle applied from the wheel side of the steering shaft (step 3).

In step 3, if the additional steering force is not a disturbance but is added by the driver from the operating side of the steering shaft, whether or not the absolute value of the torque Th corresponding to the additional steering force is equal to or greater than the set value T1. Is determined (step 4). That is, the total torque T transmitted by the steering shaft is determined from the difference between the rotation angle of the steering shaft determined by the first resolver 53 and the rotation angle of the steering shaft determined by the second resolver 65, and the total torque T is calculated. By subtracting the torque due to the steering force generated by the brushless motor 50 from T, the torque T corresponding to the additional steering force is obtained.
Find h. The torque due to the steering force generated by the brushless motor 50 is obtained from the value of the drive current Ia of the brushless motor 50.

When the absolute value of the torque Th corresponding to the additional steering force of the driver is equal to or greater than the set value T1, an open signal is output to the normally closed contact 49. As a result, the power applied to the brushless motor 50 is cut off, the automatic steering mode is released, and the mode is switched to the normal steering mode (step 5). The set value T1 can be determined based on a steering force generated by the driver when indicating a steering intention.

When the absolute value of the torque Th corresponding to the additional steering force of the driver is less than the set value T1, the automatic steering is continued.

In step 3, if the additional steering force is a disturbance from the outside of the vehicle applied from the wheel side of the steering shaft, the direction of the additional steering force is the same as the direction of the steering force generated by the brushless motor 50. It is determined whether it is the direction (step 6). The direction of the additional steering force is, as described above, a2-a1 <0, b2-b1 <0, a
2-b2 <0 or a2-a1 <0, b2-b1
If <0, a2-b2> 0, it is determined to be rightward, and a2-a1> 0, b2-b1> 0, a2-b2>.
0 or a2-a1> 0, b2-b1> 0, a2
If −b2 <0, it is determined to be the left direction, and it is determined whether the direction of the additional steering force matches the direction of the steering force generated by the brushless motor 50 based on the command signal from the control device 61. Is determined.

In step 6, if the direction of the steering force generated by the brushless motor 50 is the same as the direction of the additional steering force, the absolute value of the disturbance torque Td corresponding to the additional steering force is equal to or greater than the set value T2. Is determined (step 7).

The absolute value of the disturbance torque Td is equal to the set value T2.
At this time, an alarm signal is issued (step 8), and then an open signal is output to the normally closed contact 49 to release the automatic steering mode and switch to the normal steering mode (step 5). An alarm device (not shown) such as a buzzer or a lamp that issues an alarm to the driver in response to the alarm signal is operated.

In step 6, when the direction of the steering force generated by the brushless motor 50 is not the same as the direction of the additional steering force, in step 7, the disturbance torque Td
Is smaller than the set value T2, the disturbance torque T
The brushless motor 50 is controlled so as to generate a steering force that offsets d, thereby compensating for the influence of disturbance (step 9).
That is, by calculating the compensation torque Tc for canceling the disturbance torque Td and adding the compensation torque Tc to the target torque Tq, the brushless motor 50 is configured to generate a steering force that cancels the additional steering force. Control.
An arithmetic expression for obtaining the compensation torque Tc from the disturbance torque Td can be obtained in advance by experiments.

In the above configuration, when a steering force is applied to the vehicle from the outside based on disturbances such as unevenness and a cross wind on the traveling road, or when the driver applies the steering force during automatic steering, the steering transmitted by the steering shaft. The torque corresponding to the force changes before the actual steering angle changes. Since the operating side and the wheel side of the steering shaft rotate relative to each other due to the torque, the output value and the phase of the first resolver are different from the output value and the phase of the second resolver. The combination of the increasing and decreasing tendency and the magnitude of the output values of both resolvers 53 and 65 at the reference time is, as described above, the case where the direction of the steering force is right steering and the input side of the steering force to the steering shaft is the operation side. The case where the direction of the steering force is left steering and the input side of the steering force to the steering shaft is the operation side, and the case where the direction of the steering force is right steering and the input side of the steering force to the steering shaft is the wheel side The case and the case where the direction of the steering force is left steering and the input side of the steering force to the steering shaft is the wheel side are different from each other. Thereby, both resolvers 5 stored in advance are stored.
The relationship between the increase and decrease tendency and the magnitude of the output values of 3, 65, the relationship between the direction of the steering force and the input side of the steering force to the steering shaft, and the judgment of the increase and decrease tendency and the magnitude of the output values of both resolvers 53 and 65 at the time of reference Based on the result, the direction of the steering force and the input side of the steering force to the steering shaft can be determined. Therefore, based on the result of the determination, the brushless motor 50 can be controlled so as to cancel the steering force externally applied to the vehicle. This makes it possible to compensate for the influence of the additional steering force before the steering angle actually changes due to the additional steering force due to the disturbance. That is, the influence of the disturbance can be quickly and reliably compensated, and the behavior of the vehicle can be stabilized.

Further, according to the above configuration, when the driver applies a steering force during automatic steering, it is possible to switch to the normal steering mode before the actual steering angle changes. As a result, it is possible to quickly switch from the automatic steering mode to the normal steering mode in an emergency or the like. In addition, since it is determined whether the steering force applied during the automatic steering is applied by the driver or externally to the vehicle, it is possible to prevent accidental switching from the automatic steering mode to the normal steering mode due to disturbance. Can be prevented.

In the above configuration, the brushless motor 5
It is determined whether a steering force is externally applied to the vehicle in the same direction as the direction of the steering force at which 0 occurs. This allows
It can be determined whether the steering resistance acting on the wheels has decreased due to the decrease in the friction coefficient of the road surface. By switching from the automatic steering mode to the normal steering mode when the absolute value of the disturbance torque Td corresponding to the additional steering force is equal to or more than the set value T2, the automatic steering can be canceled when the friction coefficient of the road surface is small.

The present invention is not limited to the above embodiment. For example, a torque sensor for detecting torque transmitted by the steering shaft may be provided between the steering wheel and the steering force generating actuator.
In this case, the torque transmitted by the steering shaft based on the additional steering force can be directly obtained without subtracting the torque generated by the actuator from the total torque transmitted by the steering shaft as described above. In addition, the control device 61 controls the motor 5
The target current is determined according to the rotation angle data of 0 and the actual current value fed back from the current detection unit of the motor 50, and the current is applied to the brushless motor 50. FIG.
(1) shows the time change of the target current and the feedback current of the motor 50 in the no-load state, and (2) of FIG. 8 shows the time change of the target current and the feedback current of the motor 50 in the load state. The rotation speed α1 ° / sec of the motor 50 in the no-load state is set higher than the rotation speed α2 ° / sec in the load state. Based on characteristics such as the motor time constant and the slew rate of the circuit in the control device 61, there is a delay Δt in the time change of the feedback current with respect to the time change of the target current. If there is such a delay Δt, the desired torque cannot be accurately generated by the motor 50. Therefore, since the delay Δt can be considered to be constant regardless of the load and the rotation speed of the motor 50, the rotation speed (electric angle change speed) α1 and α2 degrees / second of the motor 50 are obtained from the rotation angle data by the control device 61. May be calculated, and the phase of the obtained target current may be advanced by the products α1 × Δt and α2 × Δt of the rotation speed and the delay.
As a result, the motor 50 can be controlled efficiently,
0 can be used evenly from low rotation to high rotation.
The relationship between the increase and decrease tendency and the magnitude of the output values of both resolvers, the direction of the steering force, and the input side of the steering force to the steering shaft is determined by the two resolvers 53, 65 with respect to the steering direction.
It changes depending on the direction of the phase change of the output and the setting at the time of reference, and is not limited to the above embodiment. Also,
The reference time may be plural instead of single as in the above embodiment. In this case, when the direction of the steering force and the determination result on the input side of the steering force to the steering shaft do not match at all the reference times, by adopting the determination result that matches at more reference times. , The accuracy of the determination can be improved. Further, the steering device of the present invention can be applied to a vehicle that does not perform automatic steering. For example, when a steering force due to the action of a disturbance is applied, the vehicle braking force is controlled to stabilize the vehicle behavior. In this case, it can be used to determine the presence or absence of the additional steering force due to the disturbance and the direction of the additional steering force.

[0057]

According to the present invention, it is possible to provide a vehicle steering apparatus capable of quickly and reliably determining the input side and direction of a steering force transmitted by a steering shaft, and a steering apparatus capable of automatically steering a vehicle. The effect can be compensated quickly and reliably, the behavior of the vehicle can be stabilized, the automatic steering can be released on frozen roads with a low coefficient of friction, etc. and the behavior of the vehicle can no longer be controlled. In such a case, it is possible to quickly switch to the normal steering mode according to the driver's intention without being affected by disturbance.

[Brief description of the drawings]

FIG. 1 is a sectional view of a steering device for a vehicle according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a hydraulic circuit diagram of the steering device of the vehicle according to the embodiment of the present invention.

FIG. 4 is a block diagram showing a control system according to the embodiment of the present invention.

5 (1) to (4) are diagrams showing a change over time of the output of each resolver of the steering device of the vehicle according to the embodiment of the present invention.

FIG. 6 is a diagram illustrating the operation of the vehicle steering device according to the embodiment of the present invention.

FIG. 7 is a flowchart showing a control procedure of the steering device of the vehicle according to the embodiment of the present invention.

FIGS. 8A and 8B are diagrams showing a time change of a target current and a feedback current of the motor according to the embodiment of the present invention;

[Explanation of symbols]

2 Input shaft 4 Output shaft 50 Brushless motor (steering force generating actuator) 53 First resolver 61 Controller 61a Storage device 65 Second resolver W Wheel

Claims (5)

[Claims] 1. A steering shaft for transmitting a steering force to a wheel, wherein an operating side and a wheel side of the steering shaft can be relatively elastically rotated in accordance with a torque corresponding to the steering force transmitted by the steering shaft. A first resolver that outputs an alternating signal whose phase changes in response to a change in the rotation angle on the operating side of the steering shaft, and a change in the rotation angle on the wheel side of the steering shaft. And a second resolver that outputs an alternating signal having the same waveform as the output signal of the first resolver. When the operation-side rotation angle of the steering shaft is equal to the wheel-side rotation angle, the first resolver The output signal and the output signal of the second resolver have the same output value and phase, and the output value and the change of the excitation voltage of both resolvers The output value of both resolvers, the magnitude of the output values of both resolvers, the direction of the steering force, and the input side of the steering force to the steering shaft at a certain reference time when the reference value becomes a constant value. Storage means for storing the relationship between the output value of the resolver and the means for determining the magnitude of the increase and decrease of the output value of both resolvers at the reference time; A steering device for a vehicle, comprising: means for determining a direction of a steering force and an input side of the steering force to a steering shaft based on the steering force. 2. A steering force generating actuator capable of generating a steering force acting on an operating side of the steering shaft, and a control device of the steering force generating actuator, wherein a steering force is generated based on a signal from the control device. The steering mode is switched between an automatic steering mode in which the steering force generated by the generating actuator is transmitted to the wheels via the steering shaft and a normal steering mode in which the steering force generated by the driver is transmitted to the wheels via the steering shaft. The vehicle steering apparatus according to claim 1, wherein the steering apparatus is enabled. 3. A value corresponding to the steering force transmitted by the steering shaft is obtained based on the outputs of the resolvers, and the steering added in the automatic steering mode other than the steering force generated by the steering force generating actuator. The input side of the force to the steering shaft is determined, and when the additional steering force is input from the operating side to the steering shaft and the absolute value of the additional steering force is equal to or greater than the set value, the automatic steering mode is switched to the normal steering mode. The vehicle steering apparatus according to claim 2, further comprising a switching unit. 4. A value corresponding to the steering force transmitted by the steering shaft is obtained based on the outputs of the resolvers, and the steering added in the automatic steering mode other than the steering force generated by the steering force generating actuator. The input side of the force to the steering shaft is determined, and it is determined whether the direction of the additional steering force input from the wheel side to the steering shaft is the same as the direction of the generated steering force of the steering force generating actuator. When an additional steering force in the same direction as the direction of the steering force generated by the steering force generating actuator is input to the steering shaft from the wheel side, and the absolute value of the additional steering force is equal to or greater than the set value, the automatic steering mode is switched to the normal mode. 3. The vehicle steering apparatus according to claim 2, further comprising means for switching to a steering mode. 5. It is determined whether or not the direction of the additional steering force input from the wheel side to the steering shaft is the same as the direction of the generated steering force of the steering force generating actuator. Means for switching from the automatic steering mode to the normal steering mode when the additional steering force in the same direction as the direction of the generated steering force is input to the steering shaft from the wheel side and the absolute value of the additional steering force is equal to or greater than the set value. The vehicle steering apparatus according to claim 3, further comprising: