JP3551427B2 - Steering control device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a steering control device that includes a steering mechanism and a turning mechanism that are mechanically disconnected from each other, and that electrically controls the interlocking of these mechanisms.
[0002]
[Prior art]
As a general control method in such a steering control device, an actual steering position of a steering wheel is detected by a steering position sensor, and a target steering position of a steered wheel is calculated based on the detection result. Then, the actual turning position of the steered wheels is detected by a turning position sensor, and the turning control is performed so that the actual turning position follows the target turning position. For this reason, for example, when a failure occurs in the steered position sensor, it becomes impossible to detect the actual steered position of the steered wheels, and it becomes difficult to continue the steering control.
[0003]
Therefore, Japanese Patent Application Laid-Open No. 5-147550 discloses that, when an abnormality occurs in a control system, a steering motor for applying a reaction force to a steering wheel and a steering motor for steering a steered wheel are electrically connected. It has been disclosed. Since the steering wheel and the rotor of the steering motor are connected, the steering motor is rotationally driven by rotating the steering wheel. By utilizing this, when a failure occurs in the control system, the steering motor is used as a generator, the generated power is supplied to the steering motor, and the steered wheels are steered.
[0004]
[Problems to be solved by the invention]
However, since electric power is generated by rotating the steering wheel, the amount of power generation changes according to the rotation speed of the steering wheel. Therefore, the electric power supplied to drive the steering motor changes according to the rotation speed of the steering wheel, so that the steering position of the steered wheels is controlled according to the steering position of the steering wheel. Was practically difficult.
[0005]
The present invention has been made to solve such a problem, and an object of the present invention is to continue turning control even when a fault occurs in a turning position sensor that detects a turning position of a turning wheel. It is to provide a steering control device capable of performing the following.
[0006]
[Means for Solving the Problems]
Therefore, a steering control device according to a first aspect of the present invention includes a steering control device that includes a steering mechanism and a turning mechanism that are mechanically disconnected from each other, and that performs an interlocking control of the steering mechanism and the turning mechanism. Steering position detecting means for detecting the steering position of the steering wheel, steering reaction force generating means for generating a steering reaction force applied to the steering wheel, turning force generating means for generating a turning force for turning the steered wheels, A steering position detecting means for detecting a steered position of the steered wheels, and a first control for controlling the steered position of the steered wheels by performing drive control of the steered force generating means in accordance with a deviation between the steered position and the steered position. The control means, the failure determination means for determining the failure of the steered position detecting means, and the control by the first control means are stopped when the steered position detecting means is determined to be faulty, and the detection is detected by the steering position detecting means. Generated by the turning force generating means in accordance with the steering position Constituting a second control means for controlling the steering force.
[0007]
In the first control means, the steered position of the steered wheels is controlled based on the deviation between the steered position and the steered position. It becomes difficult to continue. At this time, the steering wheel is not steered even if the steering wheel is operated. In such a case, the driver usually tries to further operate the steering wheel in the direction to be steered. In the present invention, failure determination is performed based on such a driver's behavior pattern that is usually performed.
[0008]
Also, when a predetermined turning force is generated by the turning force generating means, the steered wheels stop at a position where the turning force and the tire reaction force balance. Since the tire reaction force tends to increase as the steered position (steering angle) of the steered wheels increases, the steering force generated as the steering position (steering angle) of the steering wheel increases. Is increased, the steered position of the steered wheels can be controlled so as to follow the steering wheel operation. In this way, even when the steered position detecting means is out of order, the steered control of the steered wheels is continuously performed by the second control means to avoid a situation in which steering becomes difficult.
[0009]
In the steering control device according to the second aspect, the steering control device according to the first aspect further includes a vehicle speed detection unit that detects a speed of the vehicle, and the second control unit performs steering based on the steering position and the vehicle speed. The steering force generated by the force generating means is controlled.
[0010]
Since the tire reaction force changes according to the steered position of the steered wheels and the vehicle speed, the steering force generated by the steered force generating means is controlled by the second control means based on the steered position and the vehicle speed. Thus, steering control suitable for the running state of the vehicle can be performed.
[0011]
According to a third aspect of the present invention, there is provided a steering control device according to the first aspect of the present invention, wherein the failure determination unit determines that the steering load state is larger than a predetermined determination reference value for a predetermined time. Is determined to be faulty.
[0012]
In a situation where the steering control is normally performed, the steering load state is increased by the steering operation of the steering wheel, but as the steering operation is performed toward the desired steering position, the steering operation is returned. Is performed, and accordingly, the steering load state gradually decreases. On the other hand, when a failure occurs in the steered position detecting means, the control in which the steered position follows the steered position is not performed, so that the situation where the steering load state is large lasts longer than normal. Will be. Therefore, in the failure determination means, a determination reference value serving as a reference for failure determination is provided, and when the time during which the steering load state is larger than the determination reference value continues for a certain period of time, it is determined that the steered position detection means is faulty. judge.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0014]
FIG. 1 schematically shows a configuration of a steering control device according to the present embodiment. The steering control device includes a master unit 10 operated by a driver, a slave unit 20 that steers wheels 21, and a controller 30 that electrically performs interlocking control between the master unit 10 and the slave unit 20.
[0015]
The master unit 10 includes a steering shaft 12 to which a steering handle 11 is attached, a steering shaft motor 13 that generates a steering reaction force applied to the steering handle 11 by rotating the steering shaft 12, and a steering shaft 12. Is provided with a steering angle sensor 14 for detecting a steering position of the steering wheel 11 and a torque sensor 15 for detecting a steering torque applied to the steering wheel 11.
[0016]
The slave unit 20 includes a steered shaft motor 23 that generates a steering force when the steered shaft 22 is displaced and driven. Between the steered shaft motor 23 and the steered shaft 22, there is a steered shaft. A converter 24 is provided for converting the rotational movement of the shaft motor 23 into a linear movement and displacing the steered shaft 22 along the axial direction. The steered shaft 22 is provided with a stroke sensor 25 for detecting the displacement position of the steered shaft 22. Since the displaced position of the steered shaft 22 corresponds to the steered position of the wheels 21, the steered shaft 22 The steered position (steered angle) of the wheel 21 is detected by detecting the displacement position of the wheel 21 with the stroke sensor 25.
[0017]
The controller 30 receives the detection results of the steering angle sensor 14, the torque sensor 15, and the stroke sensor 25, as well as the detection results of a vehicle speed sensor 16 that detects the speed of the vehicle. The drive control of the motor 13 and the steering shaft motor 23 is performed to perform the steering position control of the wheels 21 and the reaction force control applied to the steering wheel 11. The steering shaft motor 13 and the turning shaft motor 23 are both DC motors, and drive control is performed by controlling the Duty value of the applied voltage.
[0018]
Hereinafter, each control process performed by the controller 30 will be described.
[0019]
The steering position control of the wheels 21 is performed as follows. Based on the actual steering position θr detected by the steering angle sensor 14 and the vehicle speed S detected by the vehicle speed sensor 16, a target turning position Xm of the wheel 21 corresponding to the actual steering position θr is calculated. Then, based on the deviation between the actual turning position Xr detected by the stroke sensor 25 and the calculated target turning position Xm, the duty value V1 of the voltage applied to the turning shaft motor 23 is calculated by the following equation (1). Calculated, and outputs a control signal corresponding to the calculated Duty value to the steered shaft motor 23. In the equation (1), K1 is a gain coefficient indicating the gain of the control signal.
V1 = K1 · (Xm−Xr) (1).
[0020]
The control of the reaction force applied to the steering wheel 11 is performed as follows. First, based on the actual turning position Xr detected by the stroke sensor 25 and the vehicle speed S detected by the vehicle speed sensor 16, a target steering position θm of the steering wheel 11 corresponding to the actual turning position Xr is calculated. Then, based on the deviation between the actual steering position θr detected by the steering angle sensor 14 and the calculated target steering position θm, a duty value V2 of the applied voltage applied to the steering shaft motor 13 is calculated by the following equation (2). , And outputs a control signal corresponding to the calculated Duty value to the steering shaft motor 13. In the equation (2), K2 is a gain coefficient indicating the gain of the control signal.
V2 = K2 · (θm−θr) (2).
[0021]
If a failure occurs in the stroke sensor 25, the actual steering position Xr of the wheel 21 cannot be detected, so that steering control based on the above-described equations (1) and (2) becomes difficult. For this reason, the controller 30 performs a failure determination for determining whether the stroke sensor 25 is functioning normally.
[0022]
This failure determination is performed based on the steering torque T, which is the detection result of the torque sensor 15, and the duration during which the steering torque T is larger than the determination reference value Ts. Usually, the driver takes an action to further rotate the steering wheel 11 in that direction when the course of the vehicle does not change despite the rotational operation of the steering wheel 11. When the steering handle 11 is operated in this manner, the deviation between the target steering position θm and the actual steering position θr in the above-described equation (2) is obtained regardless of the value of the target steering position θm due to a failure. It will increase even more. As a result, the steering reaction force generated by the steering shaft motor 13 increases. Therefore, in the present embodiment, the increase in the steering reaction force is detected as an example of the increase in the steering torque T in the present embodiment. Further, in order to distinguish the steering operation from a normal steering operation, if the time during which the steering torque T is greater than the determination reference value Ts continues beyond a predetermined time, it is determined that a failure has occurred in the stroke sensor 25. . This is because the actual steering position Xr is controlled so as to follow the actual steering position θr under the condition that the steering control is normally performed, and therefore, the deviation between the target steering position Xm and the actual steering position Xr. Is gradually reduced with the passage of time. However, if a failure occurs in the stroke sensor 25, the situation where the follow-up control becomes difficult and the deviation increases becomes longer than normal.
[0023]
The controller 30 determines the failure of the stroke sensor 25 according to the flowchart shown in FIG.
[0024]
The flowchart of FIG. 2 is started, for example, every 6 msec. First, in step 101 (hereinafter, the step is referred to as “S”), the steering torque T detected by the torque sensor 15 is read, and the count value t ( (Initial value: zero) is read.
[0025]
In subsequent S103, it is determined whether the read steering torque T is larger than the criterion value Ts. If the steering torque T is larger than the criterion value Ts ("Yes" in S103), S105 is performed. Then, the count value t of the timer is incremented, and this count value t is stored.
[0026]
In subsequent S107, it is determined whether or not the stored count value t of the timer is greater than a preset value ts. If the count value t is greater than ts ("Yes" in S107), the process proceeds to S109. Then, it is determined that the stroke sensor 25 has failed.
[0027]
On the other hand, when the steering torque T is equal to or smaller than the determination reference value Ts in S103 (“No” in S103), the process proceeds to S111, and the count value t of the timer at that time is reset to zero. It is determined that it is normal, and this flow ends. Also in S107, if the count value t of the timer is equal to or smaller than ts (“No” in S107), the process similarly proceeds to S113, and determines that the stroke sensor 25 is normal.
[0028]
The failure determination of the stroke sensor 25 is performed as described above. If the failure is determined in S109, the steering control based on the above-described equations (1) and (2) is immediately stopped. The operation shifts to steering control at the time of failure to be described.
[0029]
The turning control at the time of failure of the stroke sensor 25 is performed by controlling the turning force generated by the turning shaft motor 23 based on the actual steering position θr of the steering wheel 11 and the vehicle speed S. When a predetermined turning force is generated from the turning shaft motor 23, the wheel 21 is positioned at a position where the tire reaction force determined according to the turning position and the vehicle speed and the generated turning force are balanced, as shown in FIG. Steered until. Accordingly, the turning position of the wheels 21 is controlled so as to correspond to the actual steering position θr of the steering wheel 11 by generating the turning force according to the vehicle speed S and the actual steering position θr from the turning shaft motor 23. It is possible to do.
[0030]
FIG. 4 shows a flowchart of the steering control performed by the controller 30 when the stroke sensor 25 fails.
[0031]
This flowchart is started, for example, every 6 msec. First, the values of the actual steering position θr detected by the steering angle sensor 14 and the vehicle speed S detected by the vehicle speed sensor 16 are read in S201.
[0032]
In S203, the duty value of the voltage applied to the steered shaft motor 23 is calculated based on the read actual steering position θr and vehicle speed S. In this case, the duty value of the applied voltage corresponding to the actual steering position θr and the vehicle speed S is mapped in advance, and based on the detected actual steering position θr and the vehicle speed S, the applied voltage applied to the turning shaft motor 23 is determined. The Duty value may be searched by map.
[0033]
Then, in S205, a control signal corresponding to the Duty value obtained in S203 is output to the steered shaft motor 23, and this flow ends.
[0034]
By repeatedly performing S201 to S205 in this manner, even when the stroke sensor 25 is out of order, it is possible to perform the steering control in substantially the same manner as in the normal state.
[0035]
At this time, control of the reaction force applied to the steering wheel 11 is performed according to the flowchart of FIG. In this case, control is performed such that a steering reaction force corresponding to the tire reaction force obtained from the actual steering position θr and the vehicle speed S is applied to the steering wheel 11.
[0036]
This flowchart is started, for example, every 6 msec. First, the values of the actual steering position θr detected by the steering angle sensor 14 and the vehicle speed S detected by the vehicle speed sensor 16 are read in S301.
[0037]
In step S303, a value corresponding to the tire reaction force generated at this time is calculated based on the read actual steering position θr and vehicle speed S, and a steering reaction force corresponding to the calculated value is applied to the steering wheel 11. The duty value of the applied voltage to be applied to the steering shaft motor 13 is calculated so as to be applied. In this case, the duty value of the applied voltage corresponding to the actual steering position θr and the vehicle speed S is mapped in advance, and based on the detected actual steering position θr and the vehicle speed S, the duty of the applied voltage to be applied to the steering shaft motor 13 is determined. The value may be searched by map.
[0038]
Then, in S305, a control signal corresponding to the Duty value obtained in S303 is output to the steering shaft motor 13, and this flow ends.
[0039]
By repeatedly performing S301 to S305 in this manner, it is possible to control the steering reaction force according to the tire reaction force even when the stroke sensor 25 fails.
[0040]
In the embodiment described above, an example in which the turning force generated by the turning shaft motor 23 is controlled based on the actual steering position θr and the vehicle speed S has been described. However, the actual steering position θr is not considered without considering the vehicle speed S. It is also possible to control the steering force on the basis of. For example, as shown in FIG. 6, control is performed such that the magnitude of the turning force generated by the turning shaft motor 23 is proportional to the actual steering position θr, so that the turning force increases at least with the actual steering position θr. I do. In this case, since the tire reaction force increases or decreases according to the vehicle speed S at that time, the steering position of the stationary wheel 21 changes according to the vehicle speed S because the generated steering force and the tire reaction force are balanced. Become. However, since the driver normally operates the steering wheel 11 so as to obtain a desired steering amount, for example, when the driver feels that the steering amount is insufficient, the steering wheel 11 is further fed. If it is felt that the steering has gone too far, the returning operation of the steering wheel 11 is performed. As a result, the steering force generated by the steering shaft motor 23 is increased or decreased, and as a result, the steering is performed to a desired steering position.
[0041]
Further, the load state of the steering is detected based on the value of the steering torque detected by the torque sensor 15, and the failure of the stroke sensor 25 is determined. In addition to this, the applied voltage applied to the steering shaft motor 13 is determined. The steering load state can also be detected based on the Duty value, the current value flowing through the steering shaft motor 13, or the deviation between the actual steering position θr and the target steering position θm in the above-described equation (2). Also in this case, similarly, when the time during which the magnitude of the detected steering load becomes larger than the predetermined determination reference value continues for a certain period of time, it is determined that the stroke sensor 25 has failed.
[0042]
Furthermore, although the case where the steering reaction force is generated by the steering shaft motor 13 is illustrated, in addition to this, for example, a spring mechanism is used to move the steering handle 11 toward the neutral position according to the operation amount of the steering handle 11. Such a steering reaction force can be generated. Thus, even when the steering reaction force is generated using the mechanical displacement, the failure determination of the stroke sensor 25 can be performed in the same manner as in the present embodiment.
[0043]
【The invention's effect】
As described above, the steering control device according to the first aspect includes the second control unit that controls the turning force according to the steering position, so that the steering wheel can be operated even when the turning position detection unit fails. The steering control of the steered wheels according to the actual steering position can be continued, thereby avoiding a situation in which the steering becomes difficult.
[0044]
The steering control device according to claim 2 further includes a vehicle speed detection unit, and the second control unit controls the steering force based on the steering position and the vehicle speed. Suitable steering control becomes possible.
[0045]
In the steering control device according to the third aspect, the failure determination is performed by the failure determination unit based on the load state and the time, so that the failure can be distinguished from a normal operation of the steering wheel, and the failure of the steering position detection unit is accurately detected. be able to.
[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 for determining a failure of a stroke sensor.
FIG. 3 is a graph showing a relationship between a steering position and a tire reaction force.
FIG. 4 is a flowchart illustrating steering control performed when a stroke sensor fails.
FIG. 5 is a flowchart showing reaction force control performed when the stroke sensor fails.
FIG. 6 is a graph showing a relationship between an actual steering position and a generated turning force according to another embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Master part, 11 ... Steering wheel, 12 ... Steering axis, 13 ... Steering axis motor, 14 ... Steering angle sensor, 15 ... Torque sensor, 20 ... Slave part, 21 ... Wheel (steering wheel), 22 ... Steering axis , 23: Steering shaft motor, 25: Stroke sensor, 30: Controller.

Claims (3)

In a steering control device that has a steering mechanism and a steering mechanism that are mechanically uncoupled, and performs an interlocking control of the steering mechanism and the steering mechanism,
Steering position detection means for detecting a steering position of the steering wheel;
Steering reaction force generating means for generating a steering reaction force to be applied to the steering wheel;
Turning force generating means for generating a turning force for turning the steered wheels,
Turning position detecting means for detecting a turning position of the steered wheels,
First control means for performing drive control of the turning force generating means in accordance with a deviation between a steering position and a turning position, and controlling a turning position of the steered wheels;
Failure determination means for determining a failure of the steered position detection means;
When the steering position detecting means is determined to be out of order, the control by the first control means is stopped, and the steering force is generated by the steering force generating means in accordance with the steering position detected by the steering position detecting means. A second control means for controlling a turning force to be applied. It further comprises a vehicle speed detecting means for detecting the speed of the vehicle,
The steering control device according to claim 1, wherein the second control means controls a turning force generated by the turning force generating means based on the steering position and a vehicle speed. 2. The failure position determination unit according to claim 1, wherein the failure determination unit determines that the steering position detection unit has a failure when a state in which the steering load state is larger than a predetermined determination reference value continues for a predetermined time. Steering control device.

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