JP4807545B2 - Vehicle steering system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle steering apparatus that eliminates mechanical coupling between a steering wheel and a steering mechanism for steering a steering wheel.
[0002]
[Prior art]
The steering wheel and the steering mechanism for steering the steering wheel are mechanically separated to detect the steering wheel operation direction and operation amount, and based on the detection result, the steering mechanism is driven from the steering actuator. There has been proposed a vehicle steering device (so-called steer-by-wire system) that applies force.
[0003]
Such a vehicle steering apparatus is provided with a reaction force actuator for applying an operation reaction force to the steering wheel. This reaction force actuator is controlled by a control device including a computer. That is, an operation angle sensor for detecting the operation angle of the steering wheel is connected to the control device, and the control device sets the reaction force command value by multiplying the operation angle detected by the operation angle sensor by an appropriate proportional constant. The reaction force actuator is feedback-controlled based on the reaction force command value. Thus, a larger reaction force is applied to the steering wheel as the operation angle is larger, and a smaller reaction force is applied to the steering wheel as the operation angle is smaller.
[0004]
[Problems to be solved by the invention]
However, since there is no relation between the operation of the steering actuator (steering mechanism) and the control of the reaction force actuator, there is a problem that the behavior of the vehicle and the reaction force applied to the steering wheel tend to be unbalanced. . If the behavior of the vehicle and the reaction force applied to the steering wheel are not balanced, the driver may not perform a steering operation according to the behavior of the vehicle. For example, if the steering wheel is steered greatly but the reaction force applied to the steering wheel is small, the driver feels that the steering wheel is not steered sufficiently and The steering wheel is operated in the direction in which the wheel is further steered.
[0005]
In addition, since there is no relation between the operation of the steering actuator (steering mechanism) and the control of the reaction force actuator, when the steering wheel is suddenly operated, the operation of the steering actuator is delayed with respect to the operation of the steering wheel. There is a risk that the driver may feel uncomfortable.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a vehicle steering apparatus that solves the above technical problem and can apply an appropriate reaction force according to the operation of a steering actuator to an operation member.
[0006]
[Means for Solving the Problems and Effects of the Invention]
The invention of claim 1, wherein for achieving the above object, an operation member for steering the vehicle (1), have been mechanically decoupled from the operation member, steers the steering wheel of the vehicle Steering mechanism (5, 6, 7, P) for operating, operation amount detection means (11) for detecting the operation amount of the operation member, and steering amount detection means for detecting the steering amount of the steering wheel and (13), a steering actuator (2) as operating the drive source of the steering mechanism, a reaction force actuator (9) for imparting operating reaction force to the operation member, anti controlling the upper Symbol reaction force actuator Force control means (1 4 ), and the reaction force control means includes the steering actuator when the time differential value (δh ′) of the operation amount (δh) detected by the operation amount detection means is equal to or less than a predetermined value. Proportional to the physical quantity corresponding to the output of When the time differential value of the operation amount detected by the means for generating the reaction force from the reaction force actuator and the operation amount detection means is larger than a predetermined value, the reaction proportional to the physical quantity corresponding to the output of the steering actuator is obtained. In addition to the force, the reaction force proportional to the deviation (δh−δs) between the operation amount detected by the operation amount detection unit and the steering amount (δs) detected by the steering amount detection unit is A vehicle steering apparatus comprising means for generating from a force actuator .
[0007]
In addition, the alphanumeric characters in parentheses represent corresponding components in the embodiments described later. The same applies hereinafter.
According to the present invention, when the time differential value of the operation amount detected by the operation amount detection means is equal to or smaller than the predetermined value, the reaction force proportional to the physical amount corresponding to the output of the steering actuator can be generated from the reaction force actuator. . As a result, a reaction force corresponding to the operation of the steering actuator (steering of the steering wheel) can be applied to the operation member, and the operation member and the steering mechanism are mechanically linked as in the case of the steering apparatus mechanically linked. Operability can be realized.
On the other hand, when the time differential value of the operation amount detected by the operation amount detection unit is larger than a predetermined value, in addition to the reaction force proportional to the physical amount corresponding to the output of the steering actuator, the operation detected by the operation amount detection unit A reaction force proportional to the deviation between the amount and the turning amount detected by the turning amount detection means can be generated from the reaction force actuator. As a result, when the operating member is suddenly operated, a large reaction force can be applied to the operating member, so that the delay of the operation of the steering actuator relative to the operation of the operating member can be reduced.
Note that the physical quantity corresponding to the output of the steering actuator and, as described in claim 3, may be a control command value for controlling the steering actuator (Ts), according to claim 4 Thus, if the steering actuator is an electric motor, the current value (Is) flowing through the electric motor may be used.
[0008]
The invention according to claim 2 is the operation member (1) for steering the vehicle and the steering mechanism (5, which is mechanically separated from the operation member and for steering the steering wheel of the vehicle). 6, 7, P), operation amount detection means (11) for detecting the operation amount of the operation member, steering amount detection means (13) for detecting the steering amount of the steering wheel, and the steering mechanism A steering actuator (2) as an operation drive source, a reaction force actuator (9) for applying an operation reaction force to the operation member, and a reaction force control means (14) for controlling the reaction force actuator. When the time differential value (δh ′) of the operation amount (δh) detected by the operation amount detection unit is equal to or less than a predetermined value, the reaction force control means is a reaction proportional to the physical quantity corresponding to the output of the steering actuator. Force, the reaction force actue When the time differential value of the operation amount detected by the means generated from the control unit and the operation amount detection means is larger than a predetermined value, in addition to the reaction force proportional to the physical quantity corresponding to the output of the steering actuator, Proportional to the deviation (δh′−δs ′) between the time differential value of the operation amount detected by the amount detection means and the time differential value (δs ′) of the turning amount (δs) detected by the steering amount detection means. And a means for generating a reaction force generated from the reaction force actuator .
According to the present invention, when the time differential value of the operation amount detected by the operation amount detection means is equal to or smaller than the predetermined value, the reaction force proportional to the physical amount corresponding to the output of the steering actuator can be generated from the reaction force actuator. . As a result, a reaction force corresponding to the operation of the steering actuator (steering of the steering wheel) can be applied to the operation member, and the operation member and the steering mechanism are mechanically linked as in the case of the steering apparatus mechanically linked. Operability can be realized.
On the other hand, when the time differential value of the operation amount detected by the operation amount detection unit is larger than a predetermined value, in addition to the reaction force proportional to the physical amount corresponding to the output of the steering actuator, the operation detected by the operation amount detection unit A reaction force proportional to the deviation between the time differential value of the amount and the time differential value of the turning amount detected by the turning amount detection means can be generated from the reaction force actuator. As a result, when the operating member is suddenly operated, a large reaction force can be applied to the operating member, so that the delay of the operation of the steering actuator relative to the operation of the operating member can be reduced.
The physical quantity corresponding to the output of the steering actuator may be a control command value (Ts) for controlling the steering actuator, as described in claim 3. Thus, if the steering actuator is an electric motor, the current value (Is) flowing through the electric motor may be used.
If the steering actuator is an electric motor, the predetermined value may be set to a value equal to the maximum rotation speed of the electric motor.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a conceptual diagram for explaining the configuration of a vehicle steering apparatus according to an embodiment of the present invention. The vehicle steering apparatus eliminates mechanical coupling between the steering wheel 1 and the steering mechanism, and the operation of the steering actuator 2 driven in accordance with the rotation operation of the steering wheel 1 is performed on the rack shaft 5 supported by the housing 3. Is converted to a linear motion in the vehicle width direction, and the steering is achieved by converting the linear motion of the rack shaft 5 into the steering motion of the front left and right wheels 4 (steering wheels). A by-wire (SBW) system. The steering actuator 2 and the rack shaft 5 constitute a steering mechanism for turning the steering wheel 4.
[0012]
The steering actuator 2 includes, for example, an electric motor such as a brushless motor. The driving force (rotational force of the output shaft) of this electric motor is converted into a linear motion in the axial direction (vehicle width direction) of the rack shaft 5 by a motion conversion mechanism (ball screw mechanism) provided in association with the rack shaft 5. Converted. The linear motion of the rack shaft 5 is transmitted to the tie rods 6 provided so as to protrude from both ends of the rack shaft 5, and further causes the knuckle arm 7 connected to the king pin P through the tie rod 6 to rotate. Thereby, steering of the wheel 4 supported by the knuckle arm 7 is achieved.
[0013]
The steering wheel 1 is connected to a rotating shaft 8 that is rotatably supported with respect to the vehicle body. A reaction force actuator 9 for applying a steering reaction force to the steering wheel 1 is attached to the rotating shaft 8. The reaction force actuator 9 includes an electric motor such as a brushless motor having an output shaft integrated with the rotary shaft 8.
An elastic member 10 made of a spiral spring or the like is coupled to the end of the rotating shaft 8 on the opposite side of the steering wheel 1 from the vehicle body. The elastic member 10 returns the steering wheel 1 to the straight-ahead steering position by the elastic force when the reaction force actuator 9 is not applying torque to the steering wheel 1.
[0014]
In order to detect an operation input value of the steering wheel 1, an operation angle sensor 11 that detects an operation angle δh corresponding to the rotation angle of the rotary shaft 8 is provided. The rotating shaft 8 is provided with a torque sensor 12 for detecting an operation torque T applied to the steering wheel 1. On the other hand, in order to detect the output value of the steering actuator 2, a turning angle sensor 13 for detecting the turning angle δs of the wheel 4 is provided.
[0015]
The operation angle sensor 11, the torque sensor 12, and the turning angle sensor 13 are connected to a control device 14 including a computer. The control device 14 is further connected to a vehicle speed sensor 15 that detects the vehicle speed V, a yaw rate sensor 16 that detects the yaw rate γ of the vehicle, and a lateral acceleration sensor 17 that detects the lateral acceleration Gy of the vehicle.
The control device 14 sets the target turning angle δs ^* based on the operating angle δh detected by the operating angle sensor 11, the vehicle speed V detected by the vehicle speed sensor 15, the lateral acceleration Gy detected by the lateral acceleration sensor 17, and the like. Further, the steering actuator command value Ts corresponding to the deviation (δs ^* −δs) between the target turning angle δs ^* and the turning angle (actual turning angle) δs detected by the turning angle sensor 13 is appropriately controlled. The driving circuit 18 is controlled so that a driving current corresponding to the steering actuator command value Ts is supplied to the steering actuator 2 by calculation. In addition, the control device 14 obtains a reaction force actuator command value Tr by performing a predetermined calculation process, and a drive circuit 19 so that a drive current corresponding to the reaction force actuator command value Tr is supplied to the reaction force actuator 9. To control.
[0016]
FIG. 2 is a flowchart showing the flow of calculation processing executed by the control device 14 to obtain the reaction force actuator command value Tr. The control device 14 repeatedly executes the process of FIG. 2 at every predetermined control cycle.
First, the control device 14 calculates the basic reaction force command value Trb (step S1). In this embodiment, the basic reaction force command value Trb is obtained by multiplying the steering actuator command value Ts set at that time by a predetermined proportionality constant K1. That is, the control device 14 calculates the basic reaction force command value Trb according to the following equation (1).
[0017]
Trb = K1 / Ts (1)
Next, the control device 14 determines whether or not the operation angular velocity δh ′ obtained by time differentiation of the operation angle δh detected by the operation angle sensor 11 is greater than a predetermined value (step S2). The predetermined value is a known value equal to the maximum rotation speed of the steering actuator 2.
When the operating angular velocity δh ′ is equal to or lower than the predetermined value, that is, when the steering wheel 1 is operated at a rotational speed at which the steering actuator 2 can operate with sufficient responsiveness, the control device 14 performs the first (1 ) The basic reaction force command value Trb calculated according to the equation is directly used as the reaction force actuator command value Tr (step S3).
[0018]
On the other hand, when the operating angular velocity δh ′ is larger than the predetermined value, that is, when the steering wheel 1 is operated at a rotational speed exceeding the maximum rotational speed of the steering actuator 2, the control device 14 instructs the additional reaction force command. The value Trp is calculated (step S4). In this embodiment, the additional reaction force command value Trp is proportional to a deviation (δh−δs) between the operation angle δh detected by the operation angle sensor 11 and the turning angle δs detected by the turning angle sensor 13 in advance. It is obtained by multiplying by a constant K2. That is, the control device 14 calculates the additional reaction force command value Trp according to the following equation (2).
[0019]
Trp = K2 (δh−δs) (2)
When the control device 14 calculates the additional reaction force command value Trp in accordance with the above equation (2), the basic reaction force command value Trb in which the calculated additional reaction force command value Trp is calculated in accordance with the above equation (1). And a value (Trb + Trp) obtained thereby is set as a reaction force actuator command value Tr (step S5).
As described above, in this embodiment, the basic reaction force command value Trb is calculated by multiplying the steering actuator command value Ts by a predetermined proportional constant K1, and the rotation speed at which the steering actuator 2 can operate with sufficient responsiveness. When the steering wheel 1 is operated, the basic reaction force command value Trb is set to the reaction force actuator command value Tr as it is, and the reaction force actuator 9 is controlled based on the reaction force actuator command value Tr = Trb. Done. As a result, a reaction force corresponding to the steering of the steering wheel 4 (the behavior of the vehicle) can be applied to the steering wheel 1, and the steering device in which the steering wheel and the steering mechanism are mechanically linked, Similar operability can be realized.
[0020]
Further, when the steering wheel 1 is operated at a rotational speed exceeding the maximum rotational speed of the steering actuator 2, the operation angle δh detected by the operation angle sensor 11 and the turning angle are added to the basic reaction force command value Trb. A value obtained by adding the additional reaction force command value Trp calculated by multiplying the deviation from the turning angle δs detected by the sensor 13 by a predetermined proportionality constant K2 is set as the reaction force actuator command value Tr. Then, the reaction force actuator 9 is controlled based on the reaction force actuator command value Tr = Trb + Trp. As a result, a large reaction force is applied to the steering wheel 1, so that the delay in the operation of the steering actuator 2 with respect to the operation of the steering wheel 1 can be reduced. Therefore, the steering feeling can be improved.
[0021]
Although one embodiment of the present invention has been described above, the present invention can be implemented in other forms. For example, in the above-described embodiment, the basic reaction force command value Trb is calculated by multiplying the steering actuator command value Ts by a predetermined proportional constant K1, but the basic reaction force command value Trb is calculated by the steering actuator 2 being electrically operated. In the case of a motor, it may be calculated by multiplying the current value Is actually flowing through the electric motor by a predetermined proportional constant K3. That is, the basic reaction force command value Trb may be calculated according to the following equation (3).
[0022]
Trb = K3 ・ Is (3)
In the above-described embodiment, the additional reaction force command is obtained by multiplying the deviation between the operation angle δh detected by the operation angle sensor 11 and the turning angle δs detected by the turning angle sensor 13 by a predetermined proportional constant K2. Although the value Trp is calculated, the additional reaction force command value Trp is calculated based on the time differential value δh ′ of the operation angle δh detected by the operation angle sensor 11 and the turning angle δs detected by the turning angle sensor 13. The deviation from the time differential value δs ′ may be calculated by multiplying a predetermined proportionality constant K4. That is, the additional reaction force command value Trp may be calculated according to the following equation (4).
[0023]
Trp = K4 (δh'-δs') (4)
In addition, various design changes can be made within the scope of matters described in the claims.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram for illustrating a configuration of a vehicle steering apparatus according to an embodiment of the present invention.
FIG. 2 is a flowchart showing a flow of calculation processing for obtaining a reaction force command value Tr.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Steering actuator 5 Rack axis | shaft 6 Tie rod 7 Knuckle arm 9 Reaction force actuator 11 Operation angle sensor 13 Steering angle sensor 14 Control apparatus

Claims (4)

An operating member for steering the vehicle;
It has been mechanically decoupled from the operation member, and the steering mechanism for steering a steering wheel of the vehicle,
An operation amount detection means for detecting an operation amount of the operation member;
Steering amount detection means for detecting the steering amount of the steering wheel;
A steering actuator as an operation driving source of the steering mechanism,
A reaction force actuator for applying an operation reaction force to the operation member;
And a reaction force control means for controlling the upper Symbol reaction force actuator,
The reaction force control means is
Means for generating, from the reaction force actuator, a reaction force proportional to a physical quantity corresponding to the output of the steering actuator when a time differential value of the operation amount detected by the operation amount detection means is a predetermined value or less;
When the time differential value of the operation amount detected by the operation amount detection means is larger than a predetermined value, in addition to the reaction force proportional to the physical quantity corresponding to the output of the steering actuator, it is detected by the operation amount detection means. A vehicle steering apparatus comprising: means for generating, from the reaction force actuator, a reaction force proportional to a deviation between an operation amount and a turning amount detected by the turning amount detection means . An operating member for steering the vehicle;
A steering mechanism that is mechanically separated from the operating member and steers the steering wheel of the vehicle;
An operation amount detection means for detecting an operation amount of the operation member;
Steering amount detection means for detecting the steering amount of the steering wheel;
A steering actuator as an operation drive source of the steering mechanism;
A reaction force actuator for applying an operation reaction force to the operation member;
Reaction force control means for controlling the reaction force actuator,
The reaction force control means is
Means for generating, from the reaction force actuator, a reaction force proportional to a physical quantity corresponding to the output of the steering actuator when a time differential value of the operation amount detected by the operation amount detection means is a predetermined value or less;
When the time differential value of the operation amount detected by the operation amount detection means is larger than a predetermined value, in addition to the reaction force proportional to the physical quantity corresponding to the output of the steering actuator, it is detected by the operation amount detection means. And means for generating a reaction force proportional to a deviation between the time differential value of the manipulated variable and the time differential value of the steered amount detected by the steered amount detecting means from the reaction force actuator. Steering device. The physical quantity corresponding to the output of the steering actuator and the vehicle steering device according to claim 1 or 2, characterized in that the control command value for controlling the steering actuator. The steering actuator is an electric motor, the physical quantity corresponding to the output of the steering actuator and the vehicle steering device according to claim 1 or 2, characterized in that a current flowing through the electric motor.

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