JP2005297807A - Vehicular steering control device and vehicular steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicular steering control device and a vehicular steering apparatus capable of effectively suppressing the flutter phenomenon while maintaining high responsiveness of a turning wheel at a high-speed range. <P>SOLUTION: In the vehicular steering control device to perform the transmission ratio variable control to variably change the transmission ratio of a steering transmission system, the control gain during the variable control of the transmission ratio is set according to the steering angle of a steering wheel and the vehicle speed. The control gain setting according to the steering angle of the steering wheel and the vehicle speed may be realized by changing the relationship between the control gain setting related quantity to determine the control gain and the vehicle speed according to the steering angle of the steering wheel. More effectively, if the steering angle of the steering wheel is small, the control gain in a predetermined vehicle speed range may be set to be small compared with a case of large steering angle of the steering wheel. In this situation, the predetermined vehicle speed range may be set in a high-speed range exceeding 80 km/hour. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vehicle steering control device that performs transmission ratio variable control that varies the transmission ratio of a steering transmission system, and a vehicle steering device that uses the vehicle steering control device.

Conventionally, in this type of vehicle steering apparatus, a technique is known in which the control gain at the time of transmission ratio variable control is changed according to the vehicle speed (see, for example, Patent Document 1). In this prior art, the control gain at the time of variable transmission ratio control is set to a small value in the low speed range of the vehicle speed and set to a large value in the high speed range.
JP 2000-351382 A

  However, the configuration in which the control gain is set to a large value in the high speed region as in the above-described conventional technique can improve the followability / responsiveness of the steered wheels, but the transmission rigidity of the steering transmission system is increased. There is a problem that handle vibration such as flutter and brake judder increases.

  Therefore, an object of the present invention is to provide a vehicle steering control device and a vehicle steering device that can effectively suppress the flutter phenomenon while maintaining high responsiveness of steered wheels in a high speed range.

In order to solve the above-described problem, according to one aspect of the present invention, in a vehicle steering control device that performs transmission ratio variable control that varies a transmission ratio of a steering transmission system,
There is provided a vehicle steering control device characterized in that a control gain at the time of transmission ratio variable control is set according to a steering wheel steering angle and a vehicle speed.

  In this aspect, the setting of the control gain according to the steering wheel steering angle and the vehicle speed is realized by changing the relationship between the control gain setting related amount for determining the control gain and the vehicle speed according to the steering wheel steering angle. Good. Effectively, when the steering wheel steering angle is small, the control gain in a predetermined vehicle speed range may be set smaller than when the steering wheel steering angle is large. In this case, the predetermined vehicle speed range may be set within a high speed range exceeding 80 km / h, which is a speed range where flutter is generally generated.

According to another aspect of the present invention, in the vehicle steering control device that performs transmission ratio variable control for varying the transmission ratio of the steering transmission system,
A vehicle steering control device is provided, wherein a control gain at the time of transmission ratio variable control is set according to a brake operation state and a vehicle speed.

  In this aspect, the setting of the control gain according to the brake operation state and the vehicle speed is realized by changing the relationship between the control gain setting related amount for determining the control gain and the vehicle speed according to the brake operation state. Good. Effectively, when the predetermined brake operation is detected, the control gain in the predetermined vehicle speed range may be set smaller than when the predetermined brake operation is not detected. In this case, the predetermined vehicle speed range may be set within a high speed range exceeding 60 km / h, which is a speed range where the brake judder is generally generated.

According to another aspect of the present invention,
An input shaft that transmits the rotational force of the steering wheel;
An output shaft that transmits rotational force to the steering gear;
An electric motor;
A transmission ratio variable mechanism that changes the transmission ratio between the input shaft and the output shaft by driving an electric motor;
A control device for controlling the drive of the electric motor,
The control device sets a control gain at the time of driving control of the electric motor according to a steering angle and a vehicle speed, or a vehicle steering device, or
An input shaft that transmits the rotational force of the steering wheel;
An output shaft that transmits rotational force to the steering gear;
An electric motor;
A transmission ratio variable mechanism that changes the transmission ratio between the input shaft and the output shaft by driving an electric motor;
A control device for controlling the drive of the electric motor,
There is provided a vehicle steering apparatus, wherein the control device sets a control gain at the time of driving control of an electric motor in accordance with a brake operation state and a vehicle speed.

  According to the present invention, it is possible to obtain a vehicle steering control device and a vehicle steering device capable of effectively suppressing steering wheel vibration such as flutter and brake judder while maintaining high responsiveness of steered wheels in a high speed range.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an overall view schematically showing an embodiment of a vehicle steering control apparatus 10 according to the present invention. The vehicle is provided with a steering column 12 including a steering wheel 11 operated by a driver. The steering column 12 rotatably supports a main shaft 14 that serves as a rotating shaft of the steering wheel 11. The main shaft 14 is connected to an intermediate shaft (intermediate shaft) 16 via a rubber coupling 13 or the like. The intermediate shaft 16 is connected to a steering gear box 31, and the pinion 17 is engaged with the steering rack 18 in the steering gear box 31. One end of a tie rod 19 is connected to each end of the steering rack 18 and a steered wheel (not shown) is connected to the other end of each tie rod 19 via a knuckle arm or the like (not shown).

  A transmission ratio variable mechanism 30 is provided in the steering gear box 31. The transmission ratio variable mechanism 30 has a function of varying the ratio of the steering angle of the steering wheel 11 to the tire turning angle. In the steering gear box 31, an assist motor 20 for assisting steering is provided coaxially with the rack shaft. The assist motor 20 may be provided in the steering column 12 or on the pinion shaft.

FIG. 2 is a cross-sectional view of the transmission ratio variable mechanism 30 when cut along the plane including the shaft axis, and FIG. 3 is an explanatory diagram of the transmission ratio variable principle of the transmission ratio variable mechanism 30. The transmission ratio variable mechanism 30 includes a housing 32. The housing 32 is an integral housing with the steering gear box 31, and is supported by a suspension member (not shown) or the like. The housing 32 may be separate from the housing of the steering gear box 31.
In the housing 32, an input shaft 60, an output shaft 62, a speed reducer (differential mechanism) 40, a motor 34 (DC brushless motor), a rotation angle sensor 72, and a lock mechanism 50 are accommodated. The speed reducer 40 includes a driven gear 38, a stator gear 42, a wave generator 46, and a flexible gear 48, as will be described later.

  The lower end of the intermediate shaft 16 is connected to the upper end of the input shaft 60. A stator gear 42 is provided at the lower end of the input shaft 60. A pinion 17 is provided below the output shaft 62. A driven gear 38 is provided above the output shaft 62. Gears having different numbers of teeth (the number of teeth of the driven gear 38 <the number of teeth of the stator gear 42) are formed on the inner peripheral surfaces of the driven gear 38 and the stator gear 42, respectively. Inside the driven gear 38 and the stator gear 42, a flexible gear 48 that meshes simultaneously with each gear is provided. That is, the teeth formed inside the driven gear 38 and the stator gear 42 mesh with the teeth formed outside the flexible gear 48 (the number of teeth is the same as the number of teeth of the driven gear 38). The inner side of the flexible gear 48 is fitted on the outer ring of the wave generator 46.

  A case 34 a of a motor 34 is fixed to the housing 32. The motor 34 has a motor shaft 35, and the motor shaft 35 is connected to the cam of the wave generator 46. An input shaft 60 is rotatably inserted into the motor shaft 35. That is, the input shaft 60 and the motor shaft 35 are configured to be able to rotate independently of each other.

  In this configuration, as shown in FIG. 3, when the motor shaft 35 of the motor 34 rotates, the cam of the wave generator 46 rotates and the flexible gear 48 rotates. At this time, the flexible gear 48 rotates in the stator gear 42 in a state of being deformed into an elliptical shape, and rotates the driven gear 38 on the same axis. That is, since the number of teeth of the driven gear 38 is smaller than the number of teeth of the stator gear 42, when the wave generator 46 rotates once, the driven gear 38 rotates by the difference in the number of teeth in the direction opposite to the rotation direction of the wave generator 46. (That is, actuator operating angle = rotation angle of motor 34 × reduction ratio (reduction ratio = number of teeth difference / number of teeth of driven gear 38)). On the other hand, when the steering wheel 11 (main shaft 14) rotates, the input shaft 60 (stator gear 42) rotates, and an actuator operating angle is added and transmitted to the output shaft 62.

  As described above, according to this embodiment, by changing the rotation angle (actuator operating angle) of the motor 34, the steering transmission ratio (ratio of the rotation angle of the input shaft 60 to the rotation angle of the output shaft 62: input shaft rotation angle). / Output shaft rotation angle) can be arbitrarily changed. This variable control of the steering transmission ratio (steering transmission ratio variable control) is executed by the ECU 54 of the vehicle steering control device 10. The present invention can be applied to any transmission ratio variable mechanism. For example, the transmission ratio variable mechanism 30 disclosed in Japanese Patent Application Laid-Open Nos. 2003-320943 and 2003-320945 can be used. The present invention can also be applied to a type in which the housing 32 rotates with the rotation of the steering wheel 11.

  Hereinafter, the steering transmission ratio variable control executed by the ECU 54 will be described in detail with reference to FIG. The ECU 54 is configured as a microcomputer including a CPU, a ROM, a RAM, and the like connected to each other via a bus (not shown). The ROM stores a program executed by the CPU.

  The ECU 54 includes a steering angle sensor 74 provided on the intermediate shaft 16 or the main shaft 14, a vehicle speed sensor 76 (wheel speed sensor) provided on each wheel, and an output angle sensor (pinion rotation angle sensor) provided on the output shaft 62. 78 is connected. Detection signals from the steering angle sensor 74, the vehicle speed sensor 76, and the output angle sensor 78 are input to the ECU 54 at predetermined intervals (step 100). The steering angle sensor 74 outputs a detection signal corresponding to the steering angle of the steering wheel 11, the vehicle speed sensor 76 outputs a detection signal corresponding to the amount of rotation of the wheel, and the output angle sensor 78 includes an output shaft 62. A detection signal corresponding to the rotation angle (pinion rotation angle) is output.

  The ECU 54 determines a steering transmission ratio G corresponding to the vehicle speed V obtained in step 100 using, for example, a map as shown in FIG. 5 (step 110). In FIG. 5, the steering transmission ratio is set to the quickest (low) value in the low speed range, thereby reducing the amount of turning operation (number of times of turning) at the time of stationary or U-turn. . In the medium speed range, the speed gradually changes from quick to slow (high) as the vehicle speed increases, and in the high speed range, the slowest value is set to achieve a gentle and stable steering feeling. ing. The ECU 54 may switch and use a plurality of different maps according to the traveling state of the vehicle (for example, μ on the road surface).

The ECU 54 sets the target output angle θ _TGT (= θ _IN) based on the steering transmission ratio G derived in step 110 with respect to the steering angle θ _IN (input angle) from the steering angle sensor 74 obtained in step 100. / G) is determined (step 120). The ECU 54 also detects an angle deviation e (= θ _TGT −θ _OUT ) between the detected angle θ _OUT (output angle) from the output angle sensor 78 obtained in step 100 and the target output angle θ _TGT derived in step 120. ) And an absolute value | e | of the angle deviation e is calculated (step 130).

  The ECU 54 derives and sets the proportional gain P using | e | derived in step 130 (step 140). The process of step 140 will be described later with reference to FIGS.

  The ECU 54 generates a drive signal for the motor 34 based on the proportional gain P set in step 140 and outputs it to the motor 34 (step 150).

FIG. 6 shows the proportional gain setting unit 56 of the ECU 54 that performs the processing of step 140. The proportional gain setting unit 56 of the present embodiment sets the proportional gain P according to the steering angle θ _IN and the vehicle speed V.

Specifically, the proportional gain setting unit 56 first determines a correction value α1 for | e | derived in step 130. In this case, the proportional gain setting unit 56, two kinds of maps for determining the correction value α1 corresponding to the vehicle speed V (map M1, M2), to determine a correction value α1 and used according to the steering angle theta _IN.

In the example shown in FIG. 6, the map M1 is a map of a steering angle theta _IN is selected when a predetermined threshold theta _THR above, in the map M1, the correction value α1 with respect to the vehicle speed V is the vehicle speed increases V In addition, the speed gradually increases (from the low speed range to the medium speed range), and becomes a constant value in the speed range exceeding the predetermined speed. On the other hand, the map M2 is a map that is selected when the steering angle θ _IN is smaller than a predetermined threshold θ _THR (for example, 10 deg as a criterion for determining whether the vehicle is traveling straight). The map M2 is a predetermined speed region X ( For example, in the speed range around 100 km / h), the correction value α1 for the vehicle speed V is set small. This predetermined speed range X (and the correction value α1 at that time) is a speed range (typically 80 km / h to 120 km / h) in which a flutter phenomenon (resonance of the steering transmission system) occurs mainly in the steering wheel 11. Is set in advance through testing, simulation, or the like.

  As described above, the proportional gain setting unit 56 uses the map M1 or M2 to derive the correction value α1 corresponding to the vehicle speed V obtained in step 100, and to | e | derived in step 130, the correction value α1. Are added to derive a total value ALL1 (= α1 + | e |). Next, the proportional gain setting unit 56 derives and sets the proportional gain P corresponding to the total value ALL1, using a proportional gain setting map as shown in FIG. In the proportional gain setting map shown in FIG. 6, the proportional gain P with respect to the total value ALL1 is determined to increase substantially with the total value ALL1.

By the way, the transmission rigidity of the steering transmission system (responsiveness of the steering transmission system) increases as the proportional gain P increases. In the present embodiment, as described above, when the vehicle speed V obtained in step 100 belongs to the predetermined speed range X and the steering angle θ _IN is smaller than the predetermined threshold θ _THR , the proportional gain P Is set smaller. As a result, the rigidity of the steering transmission system is reduced in the speed range where the flutter phenomenon (resonance of the steering transmission system) occurs, so that vibration in the rotational direction of the steering wheel 11 due to the flutter phenomenon can be effectively suppressed. In this embodiment, the proportional gain P is set to a relatively large value in the middle and high speed regions other than the speed region where the flutter phenomenon occurs, and the necessary response of the steering transmission system is ensured.

In this embodiment, when the steering angle θ _IN is equal to or greater than the predetermined threshold θ _THR , the proportional gain P is set to a relatively large value even when the vehicle speed V belongs to the predetermined speed range X. The This is because, when the steering angle θ _IN is equal to or greater than the predetermined threshold θ _THR, it is assumed that the driver is operating the steering wheel 11, so that the possibility that the vibration of the steering wheel 11 causes discomfort to the driver is low. Rather, priority should be given to improving the response of the steering transmission system. In this respect, the switching of the above maps M1, M2, in addition to determining the threshold theta _THR a straight traveling state of the vehicle, the change rate of the steering angle theta _IN (the steering angular speed) may be implemented in consideration.

  Next, a second embodiment of the vehicle steering control apparatus 10 according to the present invention will be described with reference to FIG. In the second embodiment, the configuration other than the proportional gain setting unit 56 of the ECU 54 may be the same as that of the above-described embodiment. Therefore, the ECU 54 executes processing according to FIG. FIG. 7 shows the proportional gain setting unit 56 of the ECU 54 of the present embodiment.

  The proportional gain setting unit 56 of this embodiment sets the proportional gain P according to the brake operation state and the vehicle speed V. For this purpose, a brake switch 79 is connected to the ECU 54. The brake switch 79 is a switch that outputs an ON signal when the driver depresses the brake pedal (brake operation). The proportional gain setting unit 56 sets the correction value α1 (proportional gain) using the map M2, as shown in FIG. 7, while the ON signal from the brake switch 79 is input. On the other hand, when the ON signal from the brake switch 79 is not input, the proportional gain setting unit 56 sets the correction value α1 (proportional gain) using the map M1. Here, the maps M1 and M2 may be the same as those in the above-described embodiment.

  Therefore, in this embodiment, as described above, when the vehicle speed V obtained in step 100 belongs to the predetermined speed range X and the brake operation is performed by the driver, the proportional gain P is small. Is set. As a result, the rigidity of the steering transmission system is reduced in the speed range where the brake judder occurs, so that the vibration of the steering wheel 11 due to the brake judder can be effectively suppressed.

  In this embodiment, the proportional gain setting unit 56 outputs an output signal of a hydraulic sensor (not shown) that detects a master cylinder pressure in accordance with the brake depression force in addition to or instead of the ON signal from the brake switch 79. Based on the above, the brake operation state may be detected. In this case, for example, the proportional gain setting unit 56 performs switching from the map M1 to the map M2 when a predetermined brake operation (for example, a brake operation that generates a master cylinder pressure higher than a certain pressure) is performed. May be.

  In the present embodiment, the predetermined speed range X is determined as a speed range (typically 60 km / h to 120 km / h) in which the brake judder mainly occurs in the steering wheel 11, and is the same as the above-described embodiment. Need not be in the range.

In addition, this embodiment may be realized in combination with the first embodiment described above. For example, when the brake operation is not performed by the driver, the configuration of the first embodiment described above is adopted, and when the brake operation is performed by the driver, the correction value α1 (proportional gain) using the map M1. The setting may be adopted. In addition, a map used when the brake operation is performed by the driver and a map used when the vehicle speed V belongs to the predetermined speed range X and the steering angle θ _IN is less than the predetermined threshold θ _THR are: However, the maps are not necessarily the same, and different maps adapted to the respective situations may be prepared.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. Can be added.

  For example, in each of the above-described embodiments, a proportional gain is shown as the control gain, but a configuration in which a proportional gain, a differential gain, an integral gain, or any combination thereof is used as the control gain may be used. For example, as disclosed in Japanese Patent Application Laid-Open No. 2000-351382, the drive control of the motor 34 may be realized based on a proportional gain and a differential gain. In this case, the map switching as described above may be realized for the setting of the proportional gain and / or the differential gain.

  In each of the above-described embodiments, the proportional gain setting mode is indirectly variable by switching between two types of maps (maps M1 and M2) that define the correction value α1 corresponding to the vehicle speed V. The proportional gain setting mode may be directly variable using the gain setting map.

  Further, in each of the above-described embodiments, the proportional gain P depends on the control gain setting related amount obtained from the correction value α1 and the absolute value | e | of the angle deviation e, that is, the total value ALL1 (= α1 + | e |). Although set, the proportional gain P may be determined in relation to a control gain setting related amount defined in another mode as disclosed in, for example, Japanese Patent Application Laid-Open No. 2000-351382.

1 is an overall view schematically showing an embodiment of a vehicle steering control device 10 according to the present invention. 3 is a sectional view of a transmission ratio variable mechanism 30. FIG. It is explanatory drawing of the transmission ratio variable principle by the transmission ratio variable mechanism. 4 is a flowchart showing a flow of steering transmission ratio variable control executed by an ECU. It is a map which shows the change characteristic with respect to vehicle speed of a steering transmission ratio. It is a figure which shows the proportional gain setting part 56 of ECU54 which concerns on 1st Example. It is a figure which shows the proportional gain setting part 56 of ECU54 which concerns on 2nd Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Vehicle steering control apparatus 11 Steering wheel 12 Steering column 14 Main shaft 16 Intermediate shaft 17 Pinion 18 Steering rack 30 Transmission ratio variable mechanism 31 Steering gear box 32 Housing 34 Motor 35 Motor shaft 40 Reducer 50 Lock mechanism 54 ECU
56 Proportional gain setting section 60 Input shaft 62 Output shaft 72 Rotation angle sensor 74 Rudder angle sensor 76 Vehicle speed sensor 78 Output angle sensor 79 Brake switch

Claims (10)

In a vehicle steering control device that performs transmission ratio variable control that varies a transmission ratio of a steering transmission system,
A vehicle steering control device, wherein a control gain during variable transmission ratio control is set in accordance with a steering angle and a vehicle speed.   2. The setting of the control gain according to the steering angle of the steering wheel and the vehicle speed is realized by changing the relationship between the control gain setting related amount for determining the control gain and the vehicle speed according to the steering angle of the steering wheel. The vehicle steering control device described.   The vehicle steering control device according to claim 1 or 2, wherein when the steering wheel steering angle is small, the control gain in a predetermined vehicle speed range is set smaller than when the steering wheel steering angle is large.   4. The vehicle steering control device according to claim 3, wherein the predetermined vehicle speed range is set in a high speed range exceeding 80 km / h. In a vehicle steering control device that performs transmission ratio variable control that varies a transmission ratio of a steering transmission system,
A vehicle steering control device, wherein a control gain for variable transmission ratio control is set in accordance with a brake operation state and a vehicle speed.   The setting according to the brake operation state and the vehicle speed of the control gain is realized by changing the relationship between the control gain setting related amount for determining the control gain and the vehicle speed according to the brake operation state. The vehicle steering control device described.   The vehicle steering control device according to claim 5 or 6, wherein when a predetermined brake operation is detected, a control gain in a predetermined vehicle speed region is set to be smaller than when a predetermined brake operation is not detected.   The vehicle steering control device according to claim 7, wherein the predetermined vehicle speed range is set in a high speed range exceeding 60 km / h. An input shaft that transmits the rotational force of the steering wheel;
An output shaft that transmits rotational force to the steering gear;
An electric motor;
A transmission ratio variable mechanism that changes the transmission ratio between the input shaft and the output shaft by driving an electric motor;
A control device for controlling the drive of the electric motor,
The vehicle steering apparatus, wherein the control device sets a control gain at the time of driving control of the electric motor according to a steering wheel steering angle and a vehicle speed. An input shaft that transmits the rotational force of the steering wheel;
An output shaft that transmits rotational force to the steering gear;
An electric motor;
A transmission ratio variable mechanism that changes the transmission ratio between the input shaft and the output shaft by driving an electric motor;
A control device for controlling the drive of the electric motor,
The vehicle steering apparatus, wherein the control device sets a control gain during drive control of the electric motor in accordance with a brake operation state and a vehicle speed.

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