JP4287154B2 - Steering device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a steering apparatus, and more particularly to a steer-by-wire steering apparatus in which a steering wheel and a steering mechanism that drives a tire are not mechanically connected.
[0002]
[Prior art]
As a vehicle steering device, a so-called steer-by-wire steering device (hereinafter referred to as “SBW steering device”) in which a steering wheel and a steering mechanism for driving tires are not mechanically connected is known. In this SBW steering device, a target steering angle of a tire is calculated based on an operation amount from a steering means such as a steering wheel (including a joystick), and an actual value obtained from a sensor provided on the target steering angle and a rack shaft or the like. The steering angle of the tire is controlled by operating an actuator which is a steered wheel drive means of the steering mechanism so as to follow the target rudder angle from the actual rudder angle of the tire (for example, paragraph 0021, Patent Document 1). FIG. 3 etc.).
[0003]
In the SBW steering apparatus as described above, the steering wheel and the steering mechanism that drives the tire are not mechanically connected. Therefore, the steering response by the force that the tire receives from the ground as in the conventional general steering apparatus. Can't get. In order to provide the driver with the same steering response as a conventional steering device in which the steering wheel and the steering mechanism that drives the tire are mechanically connected, a reaction force actuator is provided on the steering wheel shaft. This gives a reaction torque. This reaction torque is given according to the amount of operation of the steering wheel by the driver. The driver operates the steering wheel against the applied reaction torque to generate steering torque.
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 2000-108914
[Problems to be solved by the invention]
As described above, when controlling the actuator that drives the tire, the steering mechanism actuator is operated so as to follow the target rudder angle from the target rudder angle and the actual rudder angle, so that the rudder angle of the tire is reduced. Control. Therefore, in order to improve the steering feeling, it is desired to control the steering angle of the tire by using the steering torque generated by the driver's steering wheel operation in addition to the target steering angle and the actual steering angle. .
[0006]
However, in general, many steering torque detection devices that detect the steering torque of the steering wheel are complicated or expensive. Moreover, since it is necessary to attach to a reaction force actuator, the reaction force actuator and the steering torque detection device increase the size of the device. Therefore, it has been desired to perform control using the steering torque without attaching the steering torque detection device.
[0007]
SUMMARY OF THE INVENTION An object of the present invention is to provide a steering device that performs advanced control using a steering torque without attaching a steering torque detection device in response to the above-mentioned demand.
[0008]
[Means and Actions for Solving the Problems]
In order to achieve the above object, a steering apparatus according to the present invention is configured as follows.
[0009]
The first steering device (corresponding to claim 1) is not mechanically connected to a steering unit (a steering wheel or a joystick or the like, hereinafter referred to as a steering wheel), and allows the driver to operate the steering wheel. A steered wheel driving unit that drives a tire as a steered wheel via a steering mechanism and a steering wheel, and a reaction force against a steering wheel operation by a driver (a reaction torque in the case of a steering wheel, A steering device including a reaction force application unit (reaction force torque generation motor ) that provides a reaction force in the case of a joystick, a vehicle speed detection unit, a steering angle sensor that detects an actual steering angle of a steered wheel, A reaction force torque calculation unit that calculates a signal for driving the reaction force application unit according to the vehicle speed detected by the vehicle speed detection means and the actual steering angle detected by the steering angle sensor. A current detector for detecting a current flowing through the reaction force applying unit, (estimated steering torque when the steering wheel, when the joystick is estimated steering force) estimated steering force according to the operation based on the current estimated steering to calculate the Calculated by a force calculation unit , a steering angle sensor that detects the steering angle of the steering unit, a target steering angle calculation unit that calculates a target steering angle based on the steering angle detected by the steering angle sensor, and an estimated steering force calculation unit An addition unit that adds the estimated steering force and the target rudder angle calculated by the target rudder angle calculation unit, and the steered wheel drive unit is configured to drive the steered wheels based on a signal output from the addition unit. Is done.
[0010]
According to the above steering device, since the steering torque generated by the driver's operation of the steering wheel is estimated by detecting the current flowing in the reaction torque generating motor connected to the steering wheel, the steering torque detection is expensive. It is possible to perform advanced control using steering torque without providing a device. Further, since the steering torque detection device is not provided, the device layout is easy to perform. Further, since the reaction torque generating motor is driven according to the vehicle speed and the steering angle (tire position) of the steered wheels (tires), the driver's steering intention facing the rotation of the motor is determined by the motor current. It has the characteristic of appearing.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.
[0014]
The configurations, shapes, sizes, and arrangement relationships described in the embodiments are merely schematically shown to the extent that the present invention can be understood and implemented. Therefore, the present invention is not limited to the embodiments described below, and can be modified in various forms without departing from the scope of the technical idea shown in the claims.
[0015]
FIG. 1 is a configuration diagram schematically showing the overall configuration of an SBW steering apparatus 10 according to the present invention. The SBW steering device 10 includes a steering wheel 11, a steering angle sensor 13 and a reaction torque generating motor 14 provided on a steering shaft 12 coupled to the steering wheel 11, a vehicle speed detection unit 15, and a steered wheel drive unit 16. And the control unit 20. The steering shaft 12 is rotatably supported on a vehicle body (not shown).
[0016]
The steering angle sensor 13 detects the rotation of the steering shaft 12 using a rotary encoder or the like, and supplies a steering angle signal θ related to the steering angle (handle angle) from the predetermined position of the steering wheel 11 to the control unit 20. Configure to The reaction torque generating motor 14 is a motor that applies a steering reaction torque to the steering wheel 11, and includes a current detection unit 14a that detects a current flowing through the motor, a gear mechanism (not shown), and the like, and is supplied from the control unit 20. A steering reaction force torque corresponding to the reaction force torque signal Mh related to the reaction force torque is applied.
[0017]
The vehicle speed detection unit 15 supplies a vehicle speed signal V related to the vehicle speed to the control unit 20. The steered wheel drive unit 16 controls the steered wheels based on the steered wheel control angle control signal θs output from the control unit 20. The rudder angle sensor 16a is a rack shaft stroke sensor provided in the steering mechanism 19 (see FIG. 2), for example, and detects the rudder angle of the tire from the detected rack position.
[0018]
The control unit 20 includes a steering angle signal θ from the steering angle sensor 13, a current signal I related to the motor current flowing through the reaction force torque generating motor 14 from the current detection unit 14a, a vehicle speed signal V from the vehicle speed detection unit 15, In response to the steering angle signal θg from the angle sensor 16 a, the reaction force torque signal Mh is output to the reaction force torque generating motor 14, and the steering angle control signal θs is output to the steered wheel drive unit 16.
[0019]
FIG. 2 is a block diagram of the SBW steering device 10 with the control unit 20 as the center. The control unit 20 calculates a target steering angle calculation unit 21 that calculates a target steering angle of the tire from the steering angle θ from the steering angle sensor 13, and a deviation calculation that calculates a deviation between the actual steering angle and the target steering angle from the steering angle sensor 16a. Unit 22, a PID controller 23 that performs proportional, integral, and differential processing on the deviation, and a reaction force torque that calculates a reaction force torque from the deviation, a tire position (steering angle), and a gain map 24G based on the vehicle speed. From the calculation unit 24, an estimated steering torque calculation unit 25 that calculates an estimated steering torque from the current flowing through the reaction torque generating motor 14, and an addition calculation unit 26 that calculates the sum of the PID-processed deviation and the estimated steering torque Composed. The reaction torque generating motor 14, the steered wheel drive unit 16, and the control unit 20 are supplied with electric power from the power source 18 and operate.
[0020]
The target rudder angle calculation unit 21 calculates the target rudder angle of the tire from the steering angle obtained from the steering angle sensor 13 provided on the steering shaft 12 connected to the steering wheel 11. Here, the target rudder angle calculation unit 21 calculates the target rudder angle from the steering angle. However, the target rudder angle may be configured to calculate the target rudder angle using the vehicle speed and the yaw rate. By configuring in this way, it is possible to calculate a target rudder angle according to the behavior of the vehicle.
[0021]
The deviation calculation unit 22 calculates the deviation of the actual steering angle that is the actual steering angle of the tire from the steering angle sensor 16 a and the target steering angle calculated by the target steering angle calculation unit 21. The deviation between the actual rudder angle and the target rudder angle is supplied to the PID controller 23 and the reaction force torque calculation unit 24. The PID controller 23 performs proportional, integral, and differential processing on the deviation, and supplies the processed signal to the addition calculation unit 26.
[0022]
The reaction torque calculation unit 24 includes a gain map 24G that determines an output duty according to the vehicle speed. FIG. 3 is a diagram showing an example of the gain map 24G. The vertical axis represents the duty and the horizontal axis represents the tire position (steering angle). V1, V2, and V3 are vehicle speeds, and the vehicle speed V1 is the highest. The reaction torque calculation unit 24 calculates the duty according to the vehicle speed and the steering angle using the gain map 24G. The duty is supplied to the reaction force torque generating motor 14.
[0023]
The motor current flowing through the reaction force torque generating motor 14 is detected by the current detection unit 14a. The detected motor current is supplied to the estimated steering torque calculator 25. The estimated steering torque calculator 25 calculates the estimated steering torque Tm according to the following equation (1), where I is the motor current, K is the motor torque constant of the motor, and m is the reduction gear ratio.
Tm = K × I × m (1)
[0024]
The calculated estimated steering torque Tm is supplied to the addition calculation unit 26. In the addition calculation unit 26, the sum of the processed signal from the PID controller 23 and the estimated steering torque Tm is calculated, and the steering angle control signal θs is output to the steered wheel drive unit 16. The steered wheel drive unit 16 drives the steered mechanism 19 based on the steered angle control signal θs to control the steered angle of the tire 17.
[0025]
Next, an abnormality detection method for the reaction force torque generating motor 14 that can be performed in the SBW steering apparatus 10 according to the present embodiment will be described. FIG. 4 is a flowchart for explaining an abnormality detection method for the reaction force torque generating motor 14. It is determined whether or not the steering angle is constant (step S101). If the steering angle is not constant, it is determined that the reaction force torque generating motor 14 is normal (step S103). When the steering angle is constant, the estimated steering torque, that is, the steering holding force is compared with the threshold value (step S102). If the steering force is less than or equal to the threshold value, it is determined that the reaction force torque generating motor 14 is normal (step S103). If the steering holding force is greater than the threshold value, it is determined that the reaction force torque generating motor 14 is abnormal (step S104).
[0026]
As a result, even if the reaction force torque generating motor 14 is in an abnormal state due to a failure or the like, the reaction force torque is generated by monitoring the estimated steering torque value (the current value detected by the current detection unit 14a). The abnormality of the motor 14 can be determined.
[0027]
Next, an abnormality detection method for the steering torque detection device that can be performed when the steering torque detection device that detects the steering torque is provided in the SBW steering device 10 according to the present embodiment will be described. FIG. 5 is a flowchart illustrating an abnormality detection method of the steering torque detection device. A steering torque detection device provided on the steering shaft 12 of the SBW steering device 10 detects steering torque generated by the driver's operation of the steering wheel. A deviation δ between the steering torque and the estimated steering torque calculated by the estimated steering torque calculation unit 25 is obtained from the current flowing in the reaction torque generating motor 14 employed in the above-described embodiment (step S201). A deviation δ between the steering torque and the estimated steering torque is compared with a threshold value (step S202). When the deviation δ between the steering torque and the estimated steering torque is equal to or less than the threshold value, it is determined that the steering torque detection device is normal (step S204). When the deviation δ between the steering torque and the estimated steering torque is larger than the threshold value, it is determined whether or not the current detection unit 14a that detects the motor current flowing through the reaction force torque generating motor 14 is abnormal (step S203). . When the current detection unit 14a is abnormal, it is determined that the deviation δ is larger than the threshold due to the abnormality of the current detection unit 14a, and it is determined that the steering torque detection device is normal (step S204). If the current detector 14a is normal, it is determined that the steering torque detector is abnormal (step S205). Since the steering torque detection device is abnormal, it is determined that the deviation δ is larger than the threshold value.
[0028]
In the case where there is a mismatch in the steering device having the steering torque detection device, the estimated steering torque is calculated as shown in the present embodiment, and this estimated steering torque is constantly compared with the actually detected steering torque. Can easily perform a failure diagnosis as an abnormality of the steering torque detection device.
[0029]
As described above, in the present embodiment, the case of the steering wheel as the steering means has been described. However, the present invention is not limited to this and can be applied to the case of a joystick. In this case, the current flowing through the reaction force applying unit that applies a reaction force to the operation of the joystick by the driver is detected, and the estimated steering force by the operation of the driver's joystick is calculated based on the detected current.
[0030]
【The invention's effect】
As apparent from the above description, according to the steering device of the present invention, the current flowing through the reaction force torque generating motor connected to the steering wheel (joystick) is detected by the current detection unit, and based on this current value, Since the steering force due to the driver's operation of the steering wheel (joystick) is estimated, advanced control using the steering force without providing an expensive steering force detection device (a steering torque detection device in the case of a steering wheel) It can be performed. Further, since it is not necessary to provide a steering force detection device, the device layout is easy to perform.
[Brief description of the drawings]
FIG. 1 is a configuration diagram schematically showing an overall configuration of a steering apparatus according to the present invention.
FIG. 2 is a block diagram of a steering apparatus with a control unit as a center.
FIG. 3 is a diagram illustrating an example of a gain map.
FIG. 4 is a flowchart illustrating an abnormality detection method for a reaction force torque generation motor.
FIG. 5 is a flowchart illustrating an abnormality detection method of the steering torque detection device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Steering device 11 Steering wheel 12 Steering shaft 13 Steering angle sensor 14 Reaction torque generating motor 14a Current detection part 15 Vehicle speed detection part 16 Steering wheel drive part 16a Steering angle sensor 17 Tire 20 Control part 21 Target rudder angle calculation part 22 Deviation Calculation unit 23 Controller 24 Reaction force torque calculation unit 24G Gain map 25 Estimated steering torque calculation unit 26 Addition calculation unit

Claims (1)

Without being mechanically connected to the steering means, the steered wheel driving means for driving the steered wheels according to the operation of the steering means, and the reaction means for the operation applied to the steering means. In a steering apparatus comprising a reaction force application means for applying,
Vehicle speed detection means;
A steering angle sensor for detecting an actual steering angle of the steered wheel;
Reaction force torque calculating means for calculating a signal for driving the reaction force applying means according to the vehicle speed detected by the vehicle speed detecting means and the actual steering angle detected by the steering angle sensor;
Current detection means for detecting a current flowing through the reaction force application means;
Estimated steering force calculating means for calculating an estimated steering force by the operation based on the current ;
A steering angle sensor for detecting a steering angle of the steering means;
Target rudder angle calculating means for calculating a target rudder angle based on the steering angle detected by the steering angle sensor;
Adding means for adding the estimated steering force calculated by the estimated steering force calculation means and the target steering angle calculated by the target steering angle calculation means;
The steered wheel driving means drives the steered wheel based on a signal output from the adding means .

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