JP2007153100A - Vehicular steering control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicular steering control device capable of adequately coping with any abnormality of a relative displacement detection means by correctly determining the abnormality of the relative displacement detection means of a transmission ratio variable device even when the target relative displacement of the transmission ratio variable device is small. <P>SOLUTION: The relative rotational angle θre of a turning angle variable device 30 is controlled to be the target relative rotational angle θret (S20-S50, S100). When the relative rotational angle θre is determined to be substantially zero (S60), the rate of change of the self-aligning torque of a steering wheel is determined based on the rate of change of the turning state quantity of a vehicle. In a circumstance in which the rate of change of the self-aligning torque is large, it is determined whether or not any abnormality occurs in a rotational angle sensor 44 depending on whether or not the rate of change of the relative rotational angle θre to be detected by the rotational angle sensor 44 is small (S80, S90). When it is determined whether or not any abnormality occurs in the rotational angle sensor 44, the turning angle variable device 30 is locked by its lock device (S110). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vehicle steering control device, and more specifically, a transmission ratio variable device that changes a steering transmission ratio that is a ratio of a steering wheel turning angle change amount to a steering operation change amount of a steering input means by a driver. The present invention relates to a vehicle steering control device.

  In a vehicle such as an automobile, a transmission ratio that changes a steering transmission ratio (corresponding to the reciprocal of the steering gear ratio) by turning a steering wheel relative to a steering input means such as a steering wheel by a steering drive means. A steering control device that includes a variable device and controls the steering transmission ratio by the transmission ratio variable device is conventionally known.

  Further, as described in, for example, Patent Document 1 below, as one of the steering control devices including a transmission ratio variable device, an electric motor that makes the steering angle ratio of the steering system variable, and an actual steering angle ratio of the steering system And a deviation between the target steering angle ratio of the steered wheel and the detected actual steering angle ratio is a predetermined value or more in a situation where the steering angle ratio of the steering system is changed by an electric motor. A steering control device having a failure detection means for determining that the actual steering angle ratio sensor is abnormal when the above condition continues for a predetermined time or more is already known.

According to such a steering control device, when a failure or abnormality occurs in the actual steering angle ratio sensor, the failure detection means detects the failure or abnormality of the actual steering angle ratio sensor. When this occurs and the steering angle ratio of the steering system cannot be properly controlled, it is possible to take appropriate measures such as stopping the control of the steering angle ratio.
JP-A-11-91604

  In general, in a steering control device equipped with a transmission ratio variable device, as described in Patent Document 1, a transmission ratio such as a deviation between a target steering angle ratio of a steered wheel and a detected actual steering angle ratio. The abnormality of the sensor can be detected on the basis of the deviation between the target rotation angle in the variable device and the detected rotation angle and the electrical signal of the sensor for detecting the rotation angle in the transmission ratio variable device.

  However, depending on the operating conditions of the transmission ratio variable device, the abnormality of the rotation angle sensor may not be detected by the abnormality determination based on the deviation of the rotation angle or the electric signal of the rotation angle sensor. In some cases, it is impossible to take necessary measures such as stopping the operation of the variable transmission ratio device.

  In particular, when the speed increasing ratio of the transmission ratio variable device is 0, the target relative rotation angle of the transmission ratio variable device is 0, and the relative rotation angle detected by a normal rotation angle sensor is also 0. On the other hand, the detected value of the rotational angle sensor becomes 0 even when a sticking abnormality occurs in the rotational angle sensor, and therefore the deviation between the target relative rotational angle and the detected value of the rotational angle sensor is abnormal even when the rotational angle sensor is normal. The case is also 0, and abnormality of the rotation angle sensor cannot be detected by abnormality determination based on the deviation of the rotation angle. The same applies to the abnormality determination based on the electrical signal of the rotation angle sensor.

  The above-mentioned problem is limited to the case where the steering transmission ratio variable device is a rotary steering transmission ratio variable device that changes the steering transmission ratio by rotating the steering wheel side member relative to the steering input means side member. The same applies to the case where the steering transmission ratio variable device is a linear displacement type steering transmission ratio variable device that changes the steering transmission ratio by linearly displacing the steering wheel side member relative to the steering input means side member. is there.

  The present invention relates to a vehicle steering control device including a steering transmission ratio variable device that changes a steering transmission ratio by displacing a steering wheel side member relative to a steering input means side member. The present invention has been made in view of the above-described problems relating to the abnormality determination of the detection means for detecting the relative displacement amount of the steering wheel side member with respect to the member, and the main problem of the present invention is the target relative displacement amount of the transmission ratio variable device. Focusing on the fact that the relative rotation angle of the variable transmission ratio device changes in a situation where the self-aligning torque of the steered wheels changes even when the size is small, the target relative displacement amount of the variable transmission ratio device is increased. Even in a small situation, the abnormality of the relative displacement detection means of the transmission ratio variable device is accurately determined without erroneous determination, and the abnormality of the relative displacement detection means is appropriately dealt with.

  According to the present invention, the main problem described above is that the structure of claim 1, that is, the steering wheel side member relative to the steering input means side member is displaced relative to the steering input amount of the steering wheel. Steering transmission ratio variable means for changing a steering transmission ratio, which is a ratio of the steering amount, detection means for detecting a relative displacement amount of the steering wheel side member with respect to the steering input means side member, and for the steering input means side member In a vehicle steering control device, comprising: means for calculating a target relative displacement amount of the steering wheel side member; and control means for controlling the steering transmission ratio variable means so that the relative displacement amount becomes the target relative displacement amount. Determining means for determining a rate of change of the self-aligning torque of the steered wheel, and a magnitude of the rate of change of the self-aligning torque when the target relative displacement amount is equal to or less than a first reference value. When the magnitude of the rate of change of the relative displacement detected by the detecting means is not more than a third reference value in a situation where it is not less than the second reference value, the steering wheel side with respect to the steering input means side member This is achieved by a vehicle steering control device having an abnormality processing means for preventing relative displacement of members.

  Further, according to the present invention, in order to effectively achieve the above main problem, in the configuration of claim 1, the determination means is configured such that the rate of change of the turning state amount of the vehicle is a fourth reference. It is comprised so that it may determine with the magnitude | size of the change rate of the said self-aligning torque being more than a 2nd reference value when it is more than a value (structure of Claim 2).

  According to the present invention, in order to effectively achieve the above main problem, in the configuration of claim 1, the determination means is a driver in a situation where the vehicle speed is equal to or higher than a fifth reference value. When the magnitude of the change rate of the steering operation amount or the steering state quantity is greater than or equal to the sixth reference value, it is determined that the magnitude of the rate of change of the self-aligning torque is greater than or equal to the second reference value. (Constitution of Claim 3)

  According to the present invention, in order to effectively achieve the main problems described above, in the configuration according to claims 1 to 3, the abnormality processing means has a first target relative displacement amount that is the first. In the situation where the change rate of the self-aligning torque is not more than a reference value and the magnitude of the change rate of the self-aligning torque is not less than the second reference value, the change rate of the relative displacement detected by the detection means is the third value. The steering wheel side member is configured to be prevented from relative displacement with respect to the steering input means side member when a state equal to or less than the reference value continues for a reference time or longer (configuration of claim 4).

  According to the present invention, in order to effectively achieve the main problems described above, in the configuration according to claims 1 to 4, the control means controls the steering input means side member with respect to the steering input means side member. When the relative displacement of the steering wheel side member is prevented, the control of the steering transmission ratio variable means is stopped (configuration of claim 5).

  In general, in a steering control device having a steering transmission ratio variable means, the steering transmission ratio variable means controls the steering input means side so that the relative displacement amount of the steering wheel side member with respect to the steering input means side member becomes the target relative displacement amount. Since the steering wheel side member is displaced relative to the member, the steering transmission ratio is controlled to become the target steering transmission ratio, so that an external force is applied to the steering wheel side member when the target relative displacement amount is zero. When the steering wheel side member is actuated and rapidly driven, the relative displacement amount suddenly becomes a value other than zero. Therefore, even when the target relative displacement amount is 0, the steering wheel side member with respect to the steering input means side member depends on the magnitude of the rate of change of the relative displacement amount when the steering wheel side member is rapidly driven. It is possible to determine whether or not the detection means for detecting the relative displacement amount is normal.

  According to the configuration of the first aspect, the rate of change of the self-aligning torque of the steered wheels is determined, the target relative displacement amount is not more than the first reference value, and the rate of change of the self-aligning torque is large. When the magnitude of the rate of change of the relative displacement detected by the detecting means is less than or equal to the third reference value in a situation where the speed is greater than or equal to the second reference value, the steering wheel side member relative to the steering input means side member Since the relative displacement is prevented, even if an abnormality occurs in the detection means in a situation where the target relative displacement amount is equal to or smaller than the first reference value, the abnormality can be reliably determined, and the steering input It is possible to reliably prevent the steering wheel side member from being displaced relative to the means side member.

  According to the configuration of claim 2, the magnitude of the rate of change of the self-aligning torque is greater than or equal to the second reference value when the rate of change of the turning state quantity of the vehicle is greater than or equal to the fourth reference value. Therefore, it is possible to reliably determine the situation where the magnitude of the rate of change of the self-aligning torque is equal to or greater than the second reference value by appropriately setting the fourth reference value.

  According to the third aspect of the present invention, in the situation where the vehicle speed is not less than the fifth reference value, the magnitude of the change rate of the steering operation amount or the steering state amount of the driver is not less than the sixth reference value. Since it is sometimes determined that the rate of change of the self-aligning torque is greater than or equal to the second reference value, the magnitude of the rate of change of the self-aligning torque can be determined by appropriately setting the fifth reference value. It is possible to reliably determine a situation that is equal to or greater than the second reference value.

  According to the fourth aspect of the present invention, the target relative displacement amount is not more than the first reference value and the rate of change of the self-aligning torque is not less than the second reference value. And the relative displacement of the steering wheel side member with respect to the steering input means side member is prevented when the change rate of the relative displacement detected by the detection means is not greater than the third reference value for a reference time or longer. Therefore, when the detection means is abnormal while reliably reducing the possibility that the relative displacement of the steering wheel side member with respect to the steering input means side member is unnecessarily blocked in a situation where the detection means is normal. The relative displacement of the steering wheel side member with respect to the steering input means side member can be reliably prevented.

  According to the fifth aspect of the present invention, when the relative displacement of the steering wheel side member with respect to the steering input means side member is blocked by the abnormal time processing means, the control of the steering transmission ratio variable means is stopped. Even if the relative displacement of the steering wheel side member relative to the steering input means side member is prevented by the processing means, it is possible to reliably prevent the control of the steering transmission ratio variable means from being continued.

[Preferred embodiment of problem solving means]
According to one preferred aspect of the present invention, in the configuration of the first to fifth aspects, the steering input means side member is an upper steering shaft, the steering wheel side member is a lower steering shaft, and steering transmission ratio control is performed. The means is configured to change the steering transmission ratio by rotationally displacing the lower steering shaft relative to the upper steering shaft (preferred aspect 1).

  According to another preferred aspect of the present invention, the steering input means side member is a tie rod member on the steering input means side, and the steering wheel side member is a steering wheel side member. The steering transmission ratio control means is configured to change the steering transmission ratio by linearly displacing the tie rod member on the steering wheel side member side relative to the tie rod member on the steering input means side ( Preferred embodiment 2).

  According to another preferred aspect of the present invention, in the configuration of the above-described claims 2 to 5 or the preferred aspect 1 or 2, the determination means is configured such that the rate of change in the lateral acceleration of the vehicle is the fourth reference. When the value is greater than or equal to the value, the magnitude of the rate of change of the self-aligning torque is determined to be greater than or equal to the second reference value (preferred aspect 3).

  According to another preferred embodiment of the present invention, in the configuration of the above-mentioned claims 2 to 5 or the preferred embodiment 1 or 2, the judging means is configured so that the rate of change of the product of the yaw rate and the vehicle speed of the vehicle is large. It is configured to determine that the magnitude of the rate of change of the self-aligning torque is greater than or equal to the second reference value when it is greater than or equal to the fourth reference value (preferred aspect 4).

  According to another preferred aspect of the present invention, in the configuration of the above-described claims 2 to 5 or the preferred aspect 1 or 2, the judging means can vary the magnitude of the change rate of the yaw rate of the vehicle according to the vehicle speed. It is configured to determine that the magnitude of the rate of change of the self-aligning torque is equal to or greater than the second reference value when the value is equal to or greater than the set fourth reference value (preferred aspect 5).

  According to another preferred aspect of the present invention, in the configuration of claims 3 to 5 or preferred aspect 1 or 2, the change rate of the steering operation amount of the driver is the change rate of the steering angle. Constructed (preferred embodiment 6).

  According to another preferred aspect of the present invention, in the configuration of claims 3 to 5 or preferred aspect 1 or 2, the change rate of the steering operation amount of the driver is the change rate of the steering angular velocity. Constructed (preferred embodiment 7).

  According to another preferred aspect of the present invention, in the configuration of claims 3 to 5 or preferred aspect 1 or 2, the change rate of the steering state quantity of the driver is the change rate of the steering torque. Constructed (Preferred Aspect 8)

  According to another preferred aspect of the present invention, in the configuration according to any one of the first to fifth aspects or the preferred aspects 1 to 8, the steering transmission ratio variable means is relative to the steering wheel side member with respect to the steering input means side member. A locking device for preventing displacement is provided, and the abnormality processing means is configured to prevent relative displacement of the steering wheel side member with respect to the steering input means side member by operating the locking device (preferable aspect 9).

  According to another preferred aspect of the present invention, in the configuration of the first to fifth aspects or the preferred aspects 1 to 9, the means for calculating the target relative displacement is the speed increasing ratio of the steering transmission ratio varying means. Is configured to calculate the target relative displacement amount so as to obtain a desired speed increase ratio (preferred aspect 10).

  According to another preferred aspect of the present invention, in the configuration of the first to fifth aspects or the preferred aspects 1 to 9, the means for calculating the target relative displacement amount has a desired steering gear ratio. The target relative displacement amount is calculated so as to satisfy (preferred aspect 11).

  The present invention will now be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic configuration diagram showing one embodiment of a vehicle steering control device according to the present invention applied to a vehicle equipped with a turning angle varying device and an electric power steering device.

  In FIG. 1, 10FL and 10FR respectively indicate the left and right front wheels of the vehicle 12, and 10RL and 10RR respectively indicate the left and right rear wheels of the vehicle. The left and right front wheels 10FL and 10FR, which are the steering wheels, are driven via a rack bar 18 and tie rods 20L and 20R by a rack-and-pinion type electric power steering device 16 driven in response to an operation of the steering wheel 14 by a driver. Steered.

  In the illustrated embodiment, the electric power steering device 16 is a rack coaxial type electric power steering device, and converts the electric motor 22 and the rotational torque of the electric motor 22 into a force in the reciprocating direction of the rack bar 18. For example, it has a ball screw type conversion mechanism 24 and functions as an auxiliary steering force generator that reduces the driver's steering burden by generating an auxiliary steering force that drives the rack bar 18 relative to the housing 26. To do. The auxiliary steering force generator may be of any configuration known in the art.

  The steering wheel 14 is drivably connected to the pinion shaft 34 of the electric power steering device 16 through an upper steering shaft 28A, a turning angle varying device 30, a lower steering shaft 28B, and a universal joint 32. In the illustrated embodiment, the turning angle varying device 30 is connected to the lower end of the upper steering shaft 28A on the housing 36A side, and to the upper end of the lower steering shaft 28B on the rotor 36B side. A motor 36 for turning driving is included.

  Thus, the turning angle varying device 30 drives the lower steering shaft 28B to rotate relative to the upper steering shaft 28A, whereby the ratio of the steering angles of the left and right front wheels 10FL and 10FR, which are the steering wheels, with respect to the rotation angle of the steering wheel 14. In other words, it functions as a steering gear ratio variable device (steering transmission ratio variable means) that changes the steering transmission ratio (the reciprocal of the steering gear ratio) and, if necessary, the left and right front wheels 10FL and 10FR regardless of the driver's steering. It also functions as an automatic steering device that performs auxiliary steering driving relative to the steering wheel 14.

  Although not shown in FIG. 1, the turning angle varying device 30 has a locking device, and the locking device is maintained in the non-operating state when the turning angle varying device 30 can be normally operated. When the variable angle device 30 cannot be operated normally, it is brought into an operating state, thereby preventing the lower steering shaft 28B from rotating relative to the upper steering shaft 28A.

  In the illustrated embodiment, the upper steering shaft 28A is provided with a steering angle sensor 40 for detecting the rotation angle of the upper steering shaft as the steering angle θ and a steering torque sensor 42 for detecting the steering torque Ts. The turning angle varying device 30 is provided with a rotation angle sensor 44 that detects the relative rotation angle of the housing 36A and the rotor 36B as the relative rotation angle θre of the lower steering shaft 22B with respect to the upper steering shaft 22A. The output is supplied to the steering control device 46.

  Further, a signal indicating the vehicle speed V detected by the vehicle speed sensor 48 and the lateral acceleration Gy of the vehicle detected by the lateral acceleration sensor 50 are input to the steering control device 46. The rotation angle sensor 44 may be replaced with a sensor that detects the rotation angle θa of the lower steering shaft 28B, and the relative rotation angle θre may be obtained as a steering angle difference θa−θ.

  As will be described later, in the steering control device 46, the target speed increase ratio Kvgt of the turning angle varying device 30 becomes a positive value when the vehicle speed V is low, and the target speed increase ratio when the vehicle speed V is high. The target acceleration ratio Kvgt of the turning angle varying device 30 is calculated based on the vehicle speed V so that Kvgt becomes a negative value, the target relative rotation angle θret is calculated based on the target acceleration ratio Kvgt, and the target relative rotation is calculated. The electric motor 36 of the turning angle varying device 30 is controlled so that the deviation between the angle θret and the relative rotation angle θre becomes zero.

  The electric power steering device 16 is controlled by an electric power steering (EPS) control device 56, and the electric power steering control device 56 exchanges necessary information with the steering control device 46. The electric power steering control device 56 calculates the basic target assist torque Tab from the map corresponding to the graph shown in FIG. 4 based on the steering torque Ts, and corresponds to the graph shown in FIG. The vehicle speed coefficient Kv is calculated from the map, the target assist torque Ta is calculated as the product of the vehicle speed coefficient Kv and the basic target assist torque Tab, and the electric power steering device 16 is controlled so that the assist torque becomes the target assist torque Ta.

  In particular, in the illustrated embodiment, the steering control device 46 calculates the speed increase ratio Kvgt of the turning angle variable device 30, and in the situation where the absolute value of the speed increase ratio Kvgt is larger than the reference value, As in the case of the above, when the absolute value of the deviation between the target relative rotation angle θret and the relative rotation angle θre is greater than or equal to the reference value, it is determined that the rotation angle sensor 44 is abnormal, the lock device is activated, and the turning angle Control of the variable device 30 is stopped.

  Further, the steering control device 46, in the situation where the absolute value of the speed increase ratio Kvgt is less than the reference value, is the absolute value of the rate of change of the lateral acceleration Gy of the vehicle as the turning state amount of the vehicle or the yaw rate γ and the vehicle speed V of the vehicle. When the absolute value of the rate of change of the product with the reference value is equal to or greater than the reference value and the absolute value of the rate of change of the relative rotation angle θre is equal to or less than the reference value has elapsed for a reference time or more, or steering as a steering operation amount When the absolute value of the change rate of the angle θ, the steering angular velocity θd, or the steering torque Ts is equal to or greater than the reference value and the absolute value of the change rate of the relative rotation angle θre is equal to or less than the reference value has passed the reference time or more. Then, it is determined that the rotation angle sensor 44 is abnormal, the lock device is activated, and the control of the turning angle varying device 30 is stopped.

  Next, the control of the turning angle varying device and the abnormality determination routine in the illustrated embodiment will be described with reference to the flowchart shown in FIG. The control according to the flowchart shown in FIG. 2 is started by closing an ignition switch not shown in the figure, and is repeatedly executed at predetermined time intervals.

  First, at step 10, a signal indicating the steering angle θ detected by the steering angle sensor 60 is read, and at step 20, the graph shown in FIG. The target speed increase ratio Kvgt of the turning angle varying device 30 is calculated from the map, and in step 30, the target relative rotation angle θret of the turning angle varying device 24 is obtained as the product of the target speed increasing ratio Kvgt and the steering angle θ. In step 40, a rotation angle deviation Δθre is calculated as a deviation between the target relative rotation angle θret and the relative rotation angle θre of the turning angle varying device 30.

In step 50, the differential value Δθred of the rotation angle deviation Δθre is calculated as, for example, a time differential value, and Kp and Kd are set as a proportional term gain and a differential term gain (both are positive constants), respectively. Accordingly, the target control voltage Vst for the electric motor 36 of the turning angle varying device 30 is calculated.
Vst = KpΔθre + KdΔθred (1)

In step 60, the speed increase ratio Kvg of the turning angle varying device 30 is calculated according to the following equation 2, and the absolute value of the speed increase ratio Kvg is equal to or less than a reference value Kvgo which is a positive constant close to 0. Is determined, that is, whether or not the relative rotation angle θre of the turning angle varying device 30 is substantially 0. If an affirmative determination is made, the process proceeds to step 80, and a negative determination is made. If yes, go to Step 70.
Kvg = θre / θ (2)

  In step 70, it is determined whether or not the state where the absolute value of the rotation angle deviation Δθre is equal to or greater than the reference value Δθreo (positive constant) continues for the reference time To (positive constant), that is, the turning angle varying device. It is determined whether or not any abnormality has occurred in 30. If an affirmative determination is made, the process proceeds to step 110. If a negative determination is made, the process proceeds to step 100.

  In step 80, it is determined whether or not an abnormality has occurred in the rotation angle sensor 44 based on the amount of turning state of the vehicle. If an affirmative determination is made, the process proceeds to step 110, and a negative determination is made. Sometimes go to step 90.

In this case, the values of the lateral acceleration Gy of the vehicle one cycle before, the yaw rate γ of the vehicle, the vehicle speed V, and the relative rotation angle θre of the turning angle varying device 30 are Gyf, γf, Vf, θref, respectively, and Gyo, γVo, θreo Each as a positive constant reference value,
(A) | Gy−Gyf | ≧ Gyo and | θre−θref | ≦ θreo
(B) | γV−γfVf | ≧ γVo and | θre−θref | ≦ θreo
When the state in which at least one of the conditions is satisfied continues for the reference time T1 (positive constant) or more, it may be determined that an abnormality has occurred in the rotation angle sensor 64.

  In step 90, it is determined whether or not an abnormality has occurred in the rotation angle sensor 44 based on the steering state quantity. If an affirmative determination is made, the process proceeds to step 110. If a negative determination is made, the process proceeds to step 110. Proceed to 100.

In this case, the steering angle θ, the steering angular velocity θd, and the steering torque Ts one cycle before are θf, θdf, and Tsf, respectively, and θo, θdo, and Tso are respectively positive constant reference values (C) | θ−θf | ≧ θo and | θre−θref | ≦ θreo
(D) | θd−θdf | ≧ θdo and | θre−θref | ≦ θreo
(E) If at least one of the conditions | Ts−Tsf | ≧ Tso and | θre−θref | ≦ θreo continues for a reference time T2 (a positive constant) or longer, the rotation angle sensor 64 is abnormal. It may be determined that it has occurred.

  In step 100, a control current is supplied to the motor 36 of the turning angle varying device 30 at the target control voltage Vst, so that the relative rotation angle θre of the turning angle varying device 30 becomes the target relative rotation angle θret. In step 110, the turning angle varying device 30 is locked by the locking device, and the relative rotation of the lower steering shaft 28B with respect to the upper steering shaft 28A is mechanically prevented and the turning angle is variable. Control of the device 30 is stopped.

  Thus, according to the illustrated embodiment, the target speed increase ratio Kvgt of the turning angle varying device 30 is calculated based on the vehicle speed V in step 20, and the target speed increase ratio Kvgt and the steering angle θ are calculated in step 30. The target relative rotation angle θret of the steered angle varying device 24 is calculated as the product of the rotation angle deviation Δθre as a deviation between the target relative rotational angle θret and the relative rotational angle θre of the steered angle varying device 30 in step 40. In step 50 and 100, the relative rotation angle θre of the turning angle varying device 30 is controlled to become the target relative rotation angle θret.

  Then, in step 60, it is determined whether or not the relative rotation angle θre of the turning angle varying device 30 is substantially 0. If it is determined that the relative rotation angle θre is substantially 0, In step 80, it is determined whether or not an abnormality has occurred in the rotation angle sensor 44 based on the product of the vehicle lateral acceleration Gy as the vehicle turning state amount or the vehicle yaw rate γ and the vehicle speed V. At 90, it is determined whether or not an abnormality has occurred in the rotation angle sensor 44 based on the steering angle θ, the steering angular velocity θd, or the steering torque Ts as the steering state quantity. If it is determined that an abnormality has occurred in the sensor 44, the turning angle varying device 30 is locked by the locking device in step 110, and the lower steering shaft 28A is lowered. With the relative rotation of the ring shaft 28B is mechanically blocked, control of the turning angle varying apparatus 30 is stopped.

  Therefore, according to the illustrated embodiment, the relative rotation angle θre of the turning angle varying device 30 is substantially 0, and it is determined whether or not the rotation angle sensor 44 is normal depending on the absolute value of the rotation angle deviation Δθre. Even in a situation in which it is impossible to do so, the change in the amount of turning state or steering state of the vehicle is relatively large, and the change in the self-aligning torque of the left and right front wheels is relatively large. It is determined whether the lower steering shaft 28B is driven to rotate relatively and a relatively large relative rotation occurs between them, and the rotation angle sensor 44 determines whether or not the rotation angle sensor 44 normally detects the relative rotation. It is possible to reliably determine whether it is normal, an abnormality occurs in the rotation angle sensor 44, and a normal steering transmission ratio (steering) by the turning angle varying device 30 is detected. When it is not possible to control the Gugiya ratio), it can be stopped reliably controlling the turning angle varying apparatus 30.

  In particular, according to the illustrated embodiment, whether or not an abnormality has occurred in the rotation angle sensor 44 is determined based on the turning state amount of the vehicle in step 80 and the determination based on the steering state amount in step 90. Therefore, it is possible to reliably and accurately determine whether or not the rotation angle sensor 44 is normal, as compared with the case where only one of determination based on the vehicle turning state amount or determination based on the steering state amount is performed. can do.

  Although the present invention has been described in detail with reference to specific embodiments, the present invention is not limited to the above-described embodiments, and various other embodiments are possible within the scope of the present invention. It will be apparent to those skilled in the art.

  For example, in the above-described embodiment, the steering transmission ratio variable means is the turning angle variable device 30 that changes the steering transmission ratio by rotationally driving the lower steering shaft 28B relative to the upper steering shaft 28A. The steering transmission ratio variable means may be of any configuration known in the art as long as the steering transmission ratio can be changed. For example, the steering input means side member is a tie rod member on the steering input means side. The steering wheel side member is a tie rod member on the steering wheel side member side, and the steering transmission ratio control means linearly displaces the tie rod member on the steering wheel side member side relative to the tie rod member on the steering input means side. It may be configured to change the steering transmission ratio.

  In the above-described embodiments, the reference values Gyo, γVo, θreo, θo, θdo, and Tso are positive constants, but any of these reference values may be variably set. Further, the above (B) is determined with respect to the rate of change of the product of the yaw rate γ and the vehicle speed V of the vehicle. For example, as a positive reference value in which γo is variably set according to the vehicle speed V, ( B) may be replaced with the following determination (B ′). (B ′) | γ−γf | ≧ γo and | θre−θref | ≦ θreo

  In the embodiment described above, it is determined that an abnormality has occurred in the rotation angle sensor 64 when the state where at least one of the conditions (A) and (B) is satisfied continues for the reference time T1 or more. However, when the state where both the conditions (A) and (B) are satisfied continues for the reference time T1 or more, the rotation angle sensor 64 is corrected so that it is determined that an abnormality has occurred. Also good.

  In the above-described embodiment, the target speed increase ratio Kvgt of the turning angle varying device 30 is calculated based on the vehicle speed V, and the turning angle varying device 24 is calculated as the product of the target speed increasing ratio Kvgt and the steering angle θ. The target relative rotation angle θret is calculated, but the target relative rotation angle θret of the turning angle varying device 24 is calculated by, for example, the target steering gear ratio Rsgt from the map corresponding to the graph shown in FIG. Then, it may be corrected so as to be calculated in a manner known in the art based on the target steering gear ratio Rsgt. In FIG. 6, Rsgo is a steering gear ratio at which the speed increasing ratio becomes zero.

  In the above-described embodiment, in steps 70, 80, and 90, it is determined whether or not the predetermined state has continued for a specific reference time To to T2. An abnormality occurs in the rotation angle sensor 64 when any of the predetermined states of Steps 70 to 90 has continued for a reference time T3 (a positive constant) from the time when any of the predetermined states of Steps 70 to 90 is reached. It may be modified so as to be determined to be present. For example, after the predetermined state of step 70 continues for ΔT1 time shorter than the reference time To, the speed ratio Kvg becomes smaller than the reference value Kvgo, the predetermined state of step 80 or 90 continues for ΔT2 time, and ΔT1 When + ΔT2 becomes equal to or greater than the reference time T3, it may be determined that an abnormality has occurred in the rotation angle sensor 64.

  In this case, an affirmative determination is made in any of steps 70 to 90 earlier than the case of the illustrated embodiment, and therefore, when an abnormality occurs in the rotation angle sensor 64, the determination is made as compared to the case of the illustrated embodiment. The abnormality can be determined at an early stage.

  Further, in the above-described embodiment, the power steering device is the electric power steering device 16, but as long as the power steering device generates a steering assist torque in accordance with at least the steering torque, for example, a hydraulic power Any configuration known in the art, such as a steering device, may be used.

It is a schematic block diagram which shows one Example of the steering control apparatus for vehicles by this invention applied to the vehicle provided with the turning angle variable apparatus and the electric power steering apparatus. It is a flowchart which shows control and abnormality determination routine of the turning angle variable apparatus in an Example. It is a graph which shows the relationship between the vehicle speed V and the target speed increase ratio Kvgt. It is a graph which shows the relationship between steering torque Ts and target basic assist torque Tab. It is a graph which shows the relationship between the vehicle speed V and the vehicle speed coefficient Kv. It is a graph which shows the relationship between vehicle speed V target steering gear ratio Rsgt.

Explanation of symbols

DESCRIPTION OF SYMBOLS 16 Electric power steering apparatus 14 Steering wheel 30 Steering angle variable apparatus 40 Steering angle sensor 42 Torque sensor 44 Rotation angle sensor 46 Steering control apparatus 48 Vehicle speed sensor 50 Lateral acceleration sensor 52 Yaw rate sensor 56 Electric power steering (EPS) control apparatus

Claims (5)

  A steering transmission ratio variable means for changing a steering transmission ratio that is a ratio of a steering wheel turning amount to a steering operation amount of the steering input means by displacing the steering wheel side member relative to the steering input means side member; Detecting means for detecting a relative displacement amount of the steering wheel side member relative to the steering input means side member; means for calculating a target relative displacement amount of the steering wheel side member relative to the steering input means side member; and the relative displacement amount Determining means for determining a rate of change of the self-aligning torque of the steered wheels in a vehicle steering control device having control means for controlling the steering transmission ratio variable means so that the target relative displacement amount becomes the target relative displacement amount; In the situation where the magnitude of the target relative displacement amount is less than or equal to the first reference value and the magnitude of the rate of change of the self-aligning torque is greater than or equal to the second reference value, the detection means detects the target relative displacement amount. An abnormality processing means for preventing relative displacement of the steering wheel side member with respect to the steering input means side member when the magnitude of the change rate of the relative displacement amount is equal to or less than a third reference value. A vehicle steering control device.   The determination means determines that the magnitude of the rate of change of the self-aligning torque is greater than or equal to a second reference value when the magnitude of the rate of change of the turning state quantity of the vehicle is greater than or equal to a fourth reference value. The vehicle steering control device according to claim 1.   In the situation where the vehicle speed is equal to or higher than the fifth reference value, the determination means is configured to perform the self-aligning when the magnitude of the change rate of the driver's steering operation amount or the steering state amount is equal to or higher than the sixth reference value. The vehicle steering control device according to claim 1, wherein the torque change rate is determined to be greater than or equal to a second reference value.   The abnormality processing means detects the detection in a situation where the magnitude of the target relative displacement is less than or equal to a first reference value and the magnitude of the rate of change of the self-aligning torque is greater than or equal to a second reference value. The relative displacement of the steering wheel side member with respect to the steering input means side member is prevented when the state in which the change rate of the relative displacement detected by the means is equal to or less than a third reference value continues for a reference time or longer. The vehicle steering control device according to claim 1, wherein the vehicle steering control device is a vehicle steering control device.   2. The control means stops the control of the steering transmission ratio varying means when the relative displacement of the steering wheel side member with respect to the steering input means side member is prevented by the abnormal time processing means. 5. The vehicle steering control device according to any one of 4 to 4.

Images