JP3577190B2 - Steering control device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a steering control device that steers a steered wheel according to rotation of a steering wheel, and in particular, a steering shaft coupled to the steering wheel and a steering mechanism that steers the steered wheel are mechanically separated, The present invention relates to a steering control device in which these connecting mechanisms are replaced by an electric control device.
[0002]
[Prior art]
FIG. 4 shows an example of a conventional steering control device (JP-A-2-85059). The steering shaft 101 to which the steering handle 102 is attached is provided with a reaction force mechanism 104 having a motor as a main element. The reaction force mechanism 104 rotates the steering shaft 101 to apply a steering reaction force to the steering handle 102. Is given. The steering shaft 101 is provided with a steering angle sensor 103 for detecting the steering angle of the steering wheel 102, and the detection result of the steering angle sensor 103 is given to the controller 100. The rotation of the steering motor 105 is transmitted to a pinion 107 via a speed reducer 106, and a rack shaft 108 meshing with the pinion 107 is driven to be displaced in the axial direction, and the steered wheels 109 are steered. The displacement of the rack shaft 108 is detected by a steering angle sensor 110, and the detection result is given to the controller 100. The controller 100 performs feedback control of the motor 105 so that the steering angle detected by the steering angle sensor 103 and the actual steering angle obtained from the detection result of the steering angle sensor 110 match.
[0003]
[Problems to be solved by the invention]
As described above, in the conventional steering control device, since the turning angle of the steered wheels 109 is controlled based on the detection result of the steering angle sensor 103, an accurate detection result that matches the actual steering angle cannot be obtained. However, there is a possibility that accurate steering control may be difficult. Further, when an abnormal detection value is output from the steering angle sensor 103 due to a failure or the like, there is a possibility that the steering control cannot be performed.
[0004]
The present invention has been made to solve such a problem, and an object of the present invention is to avoid a situation in which steering control becomes difficult even when a failure or the like occurs in a steering angle sensor, and to continuously perform the steering control. It is an object of the present invention to provide a steering control device capable of performing steering control.
[0007]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a steering control device for turning a steered wheel in conjunction with rotation of a steering wheel, wherein first, second, and third steering angle detections for detecting a steering angle of the steering wheel. Means, a steering angle determining means for determining a steering angle of a steering wheel based on a change speed of a deviation of each steering angle detected by the first, second, and third steering angle detecting means, and a steering angle determining means Target control amount calculating means for calculating a target control amount to be a target of the steering control based on the steering angle determined in the above, steering means mechanically separated from the steering wheel and connected to the steered wheels, And a turning control means for drivingly controlling the turning means so that the turning amount of the steered wheels becomes the target control amount.
[0008]
When the steering angles detected by the first, second, and third steering angle detecting means substantially match, the changing speeds of the deviations of the steering angles detected by the arbitrary two steering angle detecting means also substantially match. . Here, assuming that a failure or the like has occurred in the first steering angle detecting means, the rate of change of the deviation between the steering angles detected by the second and third steering angle detecting means becomes a value close to zero, The rate of change of the deviation of each steering angle detected by the first and second and the first and third sets of steering angle detecting means indicates a value apart from zero. When the rate of change of the deviation of the steering angle indicates a value deviating from zero, the steering angle determination means determines that the steering angle detection means including the detection result in both of the two sets is faulty and remains. The steering angle is determined based on the detection results of the two steering angle detection means. By making a determination based on the rate of change of the deviation, even in a situation where the generated deviation is small, if the rate of change of the deviation is large, it is possible to determine the failure early.
[0009]
According to a second aspect of the present invention, there is provided a steering control device for steering a steered wheel in conjunction with rotation of a steering wheel, wherein first, second, and third steering angle detections for detecting a steering angle of the steering wheel. Means for determining a steering angle of a steering wheel based on deviations of the respective steering angles detected by the first, second, and third steering angle detection means and a change speed of the deviation; A target control amount calculating means for calculating a target control amount serving as a target of the steering control based on the steering angle determined by the steering angle determining means; and a steering wheel mechanically separated from the steering wheel and connected to the steered wheels. The vehicle includes a steering unit and a steering control unit that drives and controls the steering unit so that the steering amount of the steered wheels becomes the target control amount.
[0010]
When the steering angles detected by the first, second, and third steering angle detecting means substantially coincide with each other, the deviation of the steering angles detected by any two of the steering angle detecting means and the rate of change of the deviation are also determined. They almost match. Here, assuming that a failure or the like has occurred in the first steering angle detecting means, the deviation of each steering angle detected by the second and third steering angle detecting means and the rate of change of the deviation are close to zero. The deviation of each steering angle detected by the first and second and first and third sets of steering angle detecting means and the rate of change of the deviation indicate values apart from zero. When the deviation of the steering angle and the rate of change of the deviation indicate values deviating from zero as described above, the steering angle determination means determines that the steering angle detection means including the detection results in both of the two sets is faulty. The steering angle is determined based on the detection results of the remaining two steering angle detecting means. By making a determination based on both the detected deviation of the steering angle and the rate of change of the deviation, the failure can be determined more accurately and earlier.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0012]
FIG. 1 schematically shows a configuration of a steering control device according to the present embodiment. This steering control device includes a master unit A operated by a driver, a slave unit B for steering wheels, and a control unit C for electrically controlling the master unit A and the slave unit B.
[0013]
The master unit A includes a steering shaft 2 to which the steering wheel 1 is attached, and a steering shaft motor 3 for rotating the steering shaft 2, and the steering shaft 2 detects an actual steering angle ハ ン ド ル of the steering wheel 1. Steering angle sensors 4a, 4b, 4c and a steering force sensor 5 for detecting a steering force T are provided.
[0014]
The slave section B includes a steered shaft motor 11 serving as a drive source when the steered shaft 13 is displaced and driven, and a steered shaft motor 11 is provided between the steered shaft motor 11 and the steered shaft 13. A converter 12 is provided for converting the rotational motion of the steering shaft 11 into a linear motion and displacing the steered shaft 13 in the axial direction. Both ends of the steered shaft 13 are connected to the steered wheels 14a, 14b via tie rods 15a, 15b and knuckle arms 16a, 16b, respectively. When the steered shaft 13 is displaced along the axial direction, The steering wheels 14a and 14b are steered according to the displacement amount and the displacement direction. Steering reaction force sensors 18a, 18b for detecting axial forces (steering reaction force) applied to the tie rods 15a, 15b from the left and right steered wheels 14a, 14b are attached to the tie rods 15a, 15b. Further, the turning shaft 13 is provided with a turning displacement sensor 17 for detecting the displacement of the turning shaft 13, and the turning displacement of the turning shaft 13 is detected by the turning displacement sensor 17. Thus, the actual steering amount of the steered wheels 14a and 14b can be detected.
[0015]
The control unit C includes a steering angle determination circuit 27. As will be described in detail later, the steering angle determination circuit 27 detects the steering angles Θ1, Θ2, and Θ2 detected by the three steering angle sensors 4a, 4b, and 4c, respectively. The actual steering angle の of the steering wheel 1 is determined based on the value of Θ3.
[0016]
The result of the determination by the steering angle determination circuit 27 is given to the target control amount calculator 25. The target control amount calculator 25 steers the steered wheels 14a and 14b so as to correspond to the actual steering angle Θ. The target control amount θ as a target at the time of the execution is calculated. The detection result of the turning displacement sensor 17 is given to a turning displacement calculator 22, and the turning displacement calculator 22 calculates the turning shaft 13 based on the detection result of the turning displacement sensor 17. Is obtained as a steering displacement X, and a control quantity bX (b is a coefficient corresponding to a steering displacement gear ratio) proportional to the steering displacement X is output. The target control amount θ calculated by the target control amount calculator 25 and the control amount bX calculated by the turning displacement amount calculator 22 are both given to the turning shaft motor control circuit 26. The steered shaft motor control circuit 26 controls the steered shaft motor 11 based on the given target control amount θ and control amount bX such that the steered amount of the steered wheels 14a and 14b becomes the target control amount θ. Is performed. That is, the control displacement amount Ms of the turning shaft 13 is calculated by the following equation (1), and a turning control signal corresponding to the control displacement amount Ms is output to the turning shaft motor 11. In the equation (1), Gs is a gain coefficient indicating the gain of the turning control signal.
[0017]
Ms = Gs · (θ−bX) (1)
On the other hand, the steering force applied to the steering wheel 1 is detected by the steering force sensor 5, and the detection result is given to the steering force calculator 23. The steering force calculator 23 calculates the steering force T applied to the steering shaft 2 based on the detection result of the steering force sensor 5, and rotates the steering shaft 2 in the direction to which the steering force T is applied. A control amount signal corresponding to a control amount aT (a is a coefficient corresponding to a steering force gear ratio) is output. The turning reaction force applied to the turning shaft 13 with turning is detected by turning reaction sensors 18a and 18b, and the detection result is given to a turning reaction force calculator 24. The turning reaction force calculator 24 calculates the turning reaction force F applied to the turning shaft 13 based on the detection results of the turning reaction sensors 18a and 18b. The control amount aT calculated by the steering force calculator 23 and the steering reaction force F calculated by the steering reaction force calculator 24 are both given to the steering shaft motor control circuit 21. The steering shaft motor control circuit 21 calculates the rotation control amount Mm of the steering shaft motor 3 by the following equation (2) based on the given control amount aT and the steering reaction force F, and calculates the rotation control amount Mm. Is output to the steering shaft motor 3. In the expression (2), Gm is a gain coefficient indicating the gain of the output signal.
[0018]
Mm = Gm · (aT−F) (2)
Here, the steering angle determination processing performed by the steering angle determination circuit 27 will be described with reference to the flowchart of FIG. This flowchart is started when the ignition switch is turned on, and is executed every predetermined time (for example, 2 msec.).
[0019]
First, in step 100 (hereinafter, “step” is described as “S”), the values of the steering angles Θ1, Θ2, and Θ3 detected by the three steering angle sensors 4a, 4b, and 4c are read.
[0020]
In S102, as described below, V1 and V2 obtained as the sum of the deviation (absolute value) of any two of the detected steering angles and the change speed (absolute value) of the deviation. , V3 are calculated.
[0021]
V1 = | Θ1-Θ2 | + | d (Θ1-Θ2) / dt |
V2 = | Θ2-Θ3 | + | d (Θ2-Θ3) / dt |
V3 = | Θ3-Θ1 | + | d (Θ3-Θ1) / dt |
In the above equation, in the deviation term that is the first term on the right side, when the steering angles detected by the corresponding steering angle sensors substantially match, the deviation of the steering angle becomes a value close to zero. If a failure or the like has occurred in the sensor, this deviation indicates a value away from zero. Also, by including the term of the change rate of the deviation (differential value of the deviation), which is the second term on the right side, even if the deviation of the first term is small, if the change rate is large, the value shows a large value, The steering angle sensor in which a failure or the like has occurred can be determined early. For example, when the value of the detection value 異常 1 is an abnormal value, the values of V1 and V3 including Θ1 are larger than a predetermined determination reference value A, and when the value of the detection value Θ2 is an abnormal value, Θ2 is set. If the values of V1 and V2 that include V3 and V2 are greater than the predetermined determination reference value A and the value of the detection value Θ3 is an abnormal value, the values of V2 and V3 that include Θ3 are greater than the predetermined determination reference value A. Become. Therefore, it is understood that the steering angle sensor whose detection result is commonly included in the arithmetic expression of V that has become larger than the determination reference value A has an abnormality.
[0022]
Therefore, if the value of V1, V2 or V3 calculated as the sum of the first term and the second term on the right side is larger than the predetermined criterion value A, the calculation of V larger than the criterion value A is performed. It can be seen that there is an abnormality in the detection result commonly included in the expression.
[0023]
Therefore, in S104, S106, and S108, the values of V1, V2, and V3 are compared with the criterion value A. (No)), it is determined in S110 that all the steering angle sensors 4a, 4b, 4c are functioning normally, and in S112, the steering angle calculation (Θ1 + Θ2 + Θ3) / 3 is performed. The result of the calculation is determined as the actual steering angle の of the steering wheel 1, and this routine ends.
[0024]
When V2 and V3 are larger than the determination reference value A (“Yes” in S106 and “Yes” in S114), the value of the steering angle Θ3 included in both the arithmetic expressions of V2 and V3 is abnormal. Is determined (S116), in this case, the steering angle calculation (Θ1 + Θ2) / 2 is performed in S118, the calculation result is determined as the actual steering angle の of the steering wheel 1, and the routine ends.
[0025]
If V1 and V3 are larger than the determination reference value A (“Yes” in S104, “No” in S120, “Yes” in S122), the steering included in both the arithmetic expressions of V1 and V3 is performed. It is determined that the value of the angle Θ1 is abnormal (S124). In this case, the steering angle calculation (Θ2 + Θ3) / 2 is performed in S126, and the calculation result is determined as the actual steering angle の of the steering wheel 1. End the routine.
[0026]
When V1 and V2 are larger than the determination reference value A (“Yes” in S104, “Yes” in S120, and “No” in S128), the steering included in both the arithmetic expressions of V1 and V2 is performed. It is determined that the value of the angle Θ2 is abnormal (S130). In this case, the steering angle calculation (Θ1 + Θ3) / 2 is performed in S132, and the calculation result is determined as the actual steering angle の of the steering wheel 1. End the routine.
[0027]
In the case of "Yes" in S108, only the calculation result of V3 is larger than the determination reference value A. Similarly, in the case of "No" in S114, only the calculation result of V2 is obtained. In this case, only the calculation result of V1 is larger than the determination reference value A. As described above, normally, when one steering angle sensor is abnormal, the result of the two V calculations always becomes larger than the determination reference value A. It is assumed that the detection result is normal and that an erroneous calculation has been performed due to the influence of noise or the like (S134, S136). Then, a steering angle calculation (Θ1 + Θ2 + Θ3) / 3 is performed based on the detected values of the steering angles, and the calculation result is determined as the actual steering angle の of the steering wheel 1 (S112, S138).
[0028]
When all of V1, V2, and V3 are larger than the determination reference value A (“Yes” in S104, “Yes” in S120, and “Yes” in S128), all the steering angle sensors 4a, 4b , 4c is determined to be abnormal (S140), the steering angle determination control is stopped (S142), and the process proceeds to another predetermined failure handling process.
[0029]
Through the above-described determination processing, the actual steering angle の of the steering wheel 1 is determined.
[0030]
Here, the operation of the steering control device thus configured will be schematically described. When the steering wheel 1 is rotated while the vehicle is traveling straight, the steering angle determination is performed based on the values of the steering angles Θ1, Θ2, and Θ3 detected by the three steering angle sensors 4a, 4b, and 4c. In a circuit 27, the actual steering angle の of the steering wheel 1 is determined. When the target control amount calculator 25 calculates the target control amount θ based on the actual steering angle Θ, the control displacement amount Ms is generated by the equation (1). A turning control signal corresponding to the amount Ms is output. In response to the steering control signal, the steering shaft motor 11 operates, the steering shaft 13 is displaced, and the steered wheels 14a, 14b are steered. The turning displacement X corresponding to the actual turning amount of the steered wheels 14a and 14b is given to the turning shaft motor control circuit 26 via the turning displacement calculator 22. Based on this, feedback control of the steered shaft motor 11 is performed. When θ ≒ bX, the operation of the turning shaft motor 11 stops.
[0031]
On the other hand, when the steered wheels 14a and 14b are steered, a steering reaction force F is generated. Therefore, the steering shaft motor control circuit 21 controls the signal indicating the steering reaction force F and the control according to the steering force T. The amount aT is given, and the drive control of the steering shaft motor 3, that is, the reaction force control applied to the steering shaft 2 is performed based on the above-mentioned equation (2). Then, when aT 軸 F, the operation of the steering shaft motor 3 stops.
[0032]
Thereafter, when the steering wheel 1 is turned with the steering force T exceeding this reaction force, the target control amount θ also increases because the rotation angle of the steering shaft 2 increases. For this reason, the control displacement amount Ms in the equation (1) increases, and the steered shaft 13 is driven for displacement. Since the steering reaction force F increases when the steering shaft 13 is displaced, the rotation control amount Mm in the equation (2) changes, and the steering shaft motor 3 is driven to rotate again so that the steering reaction force increases. By repeating this operation, a steering angle of the steered wheels 14a and 14b corresponding to the steering angle of the steering wheel 1 is obtained, and a steering reaction force corresponding to the steering reaction force is obtained. Similarly, when the steering wheel 1 is returned, the turning angles of the steered wheels 14a and 14b follow the returning rotation angle of the steering wheel 1, and the steering force T of the steering wheel 1 is also changed. It decreases in response to the force F.
[0033]
In the embodiment described above, in S102 of FIG. 2, the calculation formula for obtaining V1 and the like is exemplified as the sum of the deviation of the two steering angles and the change speed of the deviation, but as shown in FIG. , V1 or the like may be made only the term of the deviation of the steering angle or, as shown in FIG. 3B, only the term of the change speed of the deviation of the steering angle.
[0034]
In addition, the configuration including three steering angle sensors 4a, 4b, and 4c has been exemplified as the steering angle sensor, but the present invention is not limited to this example. By providing at least three or more steering angle sensors, as described above. Steering angle determination processing can be performed.
[0035]
Further, in the present embodiment, the case where the drive control of the steered shaft motor 11 is performed by feeding back the output of the steered displacement amount sensor 17 is illustrated, but the present invention is not limited to the case where such feedback control is performed. Absent. For example, the steered shaft motor 11 may be constituted by a step motor, the rotation amount of the step motor may be calculated according to the target control amount θ, and the rotation of the step motor may be controlled based on the calculation result. In such a case, the feedback control becomes unnecessary.
[0036]
【The invention's effect】
As described above, according to the steering control device according to each claim, the first, second, and third steering angle detecting means respectively detect the steering angle of the steering wheel, and the steering angle determining means determines The steering angle of the steering wheel is determined based on the deviation of each steering angle detected by the steering angle detecting means, the changing speed of the deviation of each steering angle, or the deviation of each steering angle and the changing speed of this deviation. Also, even when a failure or the like occurs in any of the steering angle sensors, it is possible to avoid a situation in which the steering control becomes difficult, and to continuously perform the steering control.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a steering control device according to an embodiment.
FIG. 2 is a flowchart illustrating a determination process performed by a steering angle determination circuit.
FIGS. 3A and 3B are diagrams showing another embodiment of the arithmetic processing performed in S102 in the flowchart shown in FIG. 2;
FIG. 4 is a configuration diagram schematically showing a conventional steering control device.
[Explanation of symbols]
A: Master unit, B: Slave unit, C: Control unit, 1: Steering handle, 2: Steering shaft, 3: Steering shaft motor, 4a, 4b, 4c: Steering angle sensor, 5: Steering force sensor, 11: Rolling Rudder shaft motor, 13: steered shaft, 14a, 14b: steered wheel (steered wheel), 21: steered shaft motor control circuit, 25: target control amount calculator, 26: steered shaft motor control circuit, 27: steering Angle determination circuit.

Claims (2)

In a steering control device that turns a steered wheel in conjunction with rotation of a steering handle,
First, second, and third steering angle detecting means for detecting a steering angle of the steering wheel; and a changing speed of a deviation of each steering angle detected by the first, second, and third steering angle detecting means. Steering angle determining means for determining a steering angle of the steering wheel based on the steering angle; and a target control amount for calculating a target control amount to be a target of turning control based on the steering angle determined by the steering angle determining means. A calculating means, a turning means mechanically separated from the steering wheel and connected to the steered wheels, and a turning means for controlling the turning of the steered means so that the steered amount of the steered wheels becomes the target control amount. A steering control device comprising: a rudder control unit. In a steering control device that turns a steered wheel in conjunction with rotation of a steering handle,
First, second and third steering angle detecting means for detecting a steering angle of the steering wheel; deviations of the respective steering angles detected by the first, second and third steering angle detecting means; A steering angle determining means for determining a steering angle of the steering wheel based on the change speed of the steering wheel; and a target control amount serving as a target of the turning control based on the steering angle determined by the steering angle determining means. Target control amount calculating means, mechanically separated from the steering wheel, turning means connected to steered wheels, and turning means so that the steered amount of the steered wheels becomes the target control amount. A steering control device comprising: a steering control unit that performs drive control.

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