JP7169951B2 - steering controller - Google Patents

Description

The present invention relates to a steering control device mounted on an automobile, and more particularly to a steering control device in which a steering shaft and a steering mechanism are mechanically separated.

2. Description of the Related Art In a steering control device for an automobile (hereinafter referred to as vehicle), a steering shaft connected to a steering wheel is disconnected from a steering mechanism to detect the rotation angle and rotation direction of the steering shaft, and these detection signals are generated. A so-called steer-by-wire type steering control device is known, which drives a steering shaft by controlling the amount of operation of an electric steering actuator based on .

In the steer-by-wire steering control device, the correspondence relationship between the amount of operation of the steering wheel and the amount of steering of the electric steering actuator can be set without being subject to mechanical restrictions. It has the advantage of being able to flexibly respond to changes in steering characteristics according to the running state of the vehicle, such as the length of the turning radius and whether the vehicle is accelerating or decelerating, thereby improving the degree of freedom in design. Furthermore, it has many advantages over conventional steering control devices, such as the advantage that it can be easily developed into an automatic steering system such as lane keep control.

Here, on the side of the steering shaft separated from the steering mechanism, a reaction force electric actuator for applying steering reaction torque to the steering wheel is attached. , the steering wheel and the steering mechanism are constructed so that the steering operation can be performed as if they were mechanically connected.

The steering reaction force torque means "torque in a direction opposite to the rotation direction of the steering wheel, which gives an appropriate resistance to the rotation of the steering wheel". Therefore, the direction of action of the steering reaction force torque is opposite between the "steering direction" in which the steering wheel returns to the neutral position side and the "turning direction" in which the steering reaction torque moves away from the neutral position side.

By the way, in this type of steering control device, the vehicle is driven by switching between an automatic steering mode (hereinafter referred to as active steering mode) and a manual steering mode (hereinafter referred to as manual steering mode). It is assumed that And generally, as described in Japanese Unexamined Patent Application Publication No. 2017-7484 (Patent Document 1), for example, when the driver is holding the steering wheel, the manual steering mode is executed and the steering When the driver does not hold the wheel, the active steering mode is executed.

When the manual steering mode is executed, the steering angle of the steered wheels is obtained based on the steering operation amount of the steering wheel by the driver, and the steering electric actuator is controlled and driven to achieve the obtained steering angle. is doing.

On the other hand, when the active steer mode is executed, the steering angle of the steered wheels is obtained based on the external steering command value from the automatic steering system, and the steering electric actuator is controlled so that the steering angle is obtained. , is driving. In this case, the steering wheel is automatically rotated according to the steering angle of the steered wheels by the electric actuator for reaction force, so that the rotation angle of the steering wheel and the steering angle of the steered wheels are matched.

The steering control of the automatic steering system includes lane keeping control for driving so as not to deviate from the white lines laid on the road, automatic driving control for driving along the driving route, and the like.

JP 2017-7484 A

By the way, when traveling in the active steer mode, the steered wheels are steered based on the external steering command value, and after steering, the steered wheels are controlled to return to the neutral position. At this time, the steering wheel is also returned to the neutral position corresponding to the return of the steering wheel to the neutral position. Here, since the steering wheel is provided with an air bag device or the like, the inertia of the steering wheel tends to increase.

Therefore, in the active steer mode in which the driver does not grip the steering wheel, even after the steering wheel is returned to the neutral position by the reaction force electric actuator, the steering wheel rotates past the neutral position due to inertia. phenomenon occurs. Therefore, it is necessary to give the reaction force electric actuator a damping torque command value of a predetermined magnitude so as to suppress the rotation of the steering wheel toward the neutral position.

For example, if the damping torque is small, an overshoot phenomenon occurs in which the steering wheel does not stop at the neutral position and rotates across the neutral position. For this reason, it is necessary to secure convergence of the steering wheel to the neutral position by increasing the damping torque to suppress the overshoot phenomenon of the steering wheel.

The damping torque is obtained by multiplying a basic damping torque determined from the rotation angle and rotation speed of the steering wheel by a predetermined damping coefficient, or by adding a predetermined correction damping torque.

The damping torque and the steering reaction force torque are separately calculated and obtained, and the final steering reaction force torque command value given to the reaction force electric actuator reflects the damping torque in the steering reaction force torque. .

On the other hand, when traveling in the manual steer mode, the steering wheels are steered based on the steering operation amount of the steering wheel by the driver. Even in the manual steer mode, the final steering reaction torque command value is The damping torque is reflected in the steering reaction torque.

Therefore, if the same damping coefficient or corrected damping torque as the damping coefficient set in the active steering mode or the corrected damping torque is applied, the damping torque in the turning direction or the turning back direction of the steering wheel becomes too large. , the driver feels uncomfortable operating the steering wheel. For example, a phenomenon occurs in which the driver's steering operation is hindered or the steering operation feeling is deteriorated such that the steering operation feels stuck.

An object of the present invention is to improve the convergence of the steering wheel to the neutral position in the active steer mode, and to improve the steering operation feeling in the turning direction and the turning back direction of the steering wheel in the manual steer mode. To provide a novel steering control device capable of

The present invention
a steering operation shaft that is rotatable with the rotation of the steering wheel and is mechanically separated from the steering wheel;
a reaction force electric actuator that applies a steering reaction torque to the steering operation shaft;
a steering electric actuator that generates a steering force for steering the steered wheels;
a steering member that transmits the steering force of the electric steering actuator to the steered wheels;
a steering operation amount sensor that detects a steering operation amount of a steering wheel and outputs steering operation amount information related to the steering operation amount;
a steering amount sensor that detects the steering amount of the steered wheels and outputs steering amount information regarding the steering amount;
A steering control device comprising at least control means for driving and controlling the reaction force electric actuator and the steering electric actuator based on the steering operation amount information from the steering operation amount sensor and the steering amount information from the steering amount sensor. hand,
The control means includes at least an external steering command receiving section, a steering mode switching section, a damping torque command value generating section, and a steering reaction force torque command value generating section,
The external steering command receiving unit receives external steering command information generated by the external steering control means on the basis of information about the roadway of the vehicle or information about the driving situation of the vehicle,
The steering mode switching unit switches between an active steering mode and a manual steering mode at least based on steering operation amount information from the steering operation amount sensor, and the active steering mode is switched based on external steering command information. The manual steering mode is a mode for driving and controlling the electric steering actuator, and the manual steering mode is a mode for driving and controlling the electric steering actuator based on the steering operation amount information.
The damping torque command value generating section generates the first damping torque command value when the steering mode switching section selects the active steering mode, and the steering mode switching section selects the manual steering mode. when generating a second damping torque command value,
The first damping torque command value is set by the reaction force electric actuator so as to generate torque in the direction of returning the steering wheel to the neutral position when the steering wheel exceeds the neutral position based on the steering amount information from the steering amount sensor. damping torque information for driving and controlling,
The second damping torque command value is smaller than the first damping torque command value, and generates a torque based on the steering operation amount information from the steering operation amount sensor in a direction opposite to the steering wheel turning direction and the steering back direction. is damping torque information for driving and controlling the reaction force electric actuator,
The steering reaction force torque command generator resists rotation of the steering wheel in a direction opposite to the rotation direction of the steering wheel based on at least the steering operation amount information from the steering operation amount sensor and the steering amount information from the steering amount sensor. and generates a final steering reaction torque command value by reflecting the first damping torque command value or the second damping torque command value in the steering reaction torque command value, It is characterized in that the reaction force electric actuator is driven and controlled by the final steering reaction force torque command value.

According to the present invention, in an active steering mode such as automatic driving control or lane keeping control, the reaction force electric actuator is driven based on the first damping torque command value having a relatively large damping torque. The control can improve the convergence of the steering wheel.

Further, in the manual steering mode in which the driver operates the steering wheel, the electric actuator for reaction force is driven and controlled based on the second damping torque command value having damping torque smaller than the first damping torque command value. Thus, it is possible to improve the feeling of steering operation when the driver operates the steering wheel.

1 is a configuration diagram showing a configuration of a steer-by-wire steering control device to which the present invention is applied; FIG. FIG. 2 is a cross-sectional view showing a detailed cross-section of the steering mechanism shown in FIG. 1; 2 is a configuration diagram showing an outline of a control device shown in FIG. 1; FIG. 4 is a configuration diagram showing a detailed configuration of a control device shown in FIG. 3; FIG. 1 is a block diagram showing the configuration of control blocks of a steering control device according to an embodiment of the present invention; FIG. FIG. 3 is a block diagram showing the configuration of a control block of a steering mode determination section that constitutes the present embodiment; FIG. 7 is an explanatory diagram for explaining an operation when a first intensity comparison threshold is set in the control block shown in FIG. 6; FIG. 5 is a characteristic diagram for explaining characteristics of a damping coefficient used in a damping torque command value generating section that constitutes the present embodiment; FIG. 4 is an explanatory diagram for explaining a shift state of a damping coefficient when a vehicle travels on a turning road; 6 is a flow chart showing the first half of the control flow for explaining the operation of the control block shown in FIG. 5; FIG. 6 is a flow chart showing the second half of the control flow for explaining the operation of the control block shown in FIG. 5; FIG. FIG. 4 is an explanatory diagram for explaining changes in damping coefficients when transitioning from an active steering mode to a manual steering mode; FIG. 5 is an explanatory diagram for explaining changes in damping coefficients when transitioning from manual steering mode to active steering mode; 7 is an explanatory diagram for explaining an operation when a second intensity comparison threshold is set in addition to the first intensity comparison threshold in the control block shown in FIG. 6; FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments, and various modifications and applications can be made within the technical concept of the present invention. is also included in the scope.

Before describing specific embodiments of the present invention, the configuration of a steer-by-wire steering control device will be described.

First, the steering shaft is separated from the steering shaft, the rotation angle of the steering shaft, the disturbance torque, the steering angle of the steered wheels, etc. are detected by a rotation angle sensor, current sensor, rack position sensor, etc., and based on these detection signals, the steering A steer-by-wire steering control device that controls the amount of movement of an electric actuator and a reaction force electric actuator will be described. The configuration of the steering mechanism will be described later.

In FIG. 1, steering wheels 10 are steered by tie rods 11, which are connected to steering shafts 17, which will be described later. The steering wheel 12 is connected to a steering shaft (corresponding to a steering operation shaft in the claims) 13, and the steering shaft 13 can be provided with a steering operation angle sensor or the like as required.

The steering shaft 13 is not linked to a steering shaft (also called a rack bar) 17 of the steering mechanism 16, and an electric motor for reaction force (an electric actuator for reaction force in the claims) is provided at the tip of the steering shaft 13. corresponding) 18 are provided. That is, the steering shaft 13 is not mechanically connected to the steering mechanism 16, and as a result, the steering shaft 13 and the steering mechanism 16 are separated. The reaction force electric motor 18 is driven by the controller 19 . The reaction force electric motor 18 is hereinafter referred to as the reaction force motor 18 .

The reaction force motor 18 is provided with a reaction force motor rotation angle sensor (corresponding to a steering operation amount sensor in the claims) 14. The rotation angle of the reaction force motor 18 (steering operation amount information in the claims) is equivalent) is detected. The steering operation amount sensor detects the rotation angle of the reaction force motor 18, but may be a steering operation angle sensor that detects the steering operation angle of the steering shaft. A sensor capable of detecting is in the category of a steering operation amount sensor.

Further, the reaction motor 18 is provided with a current sensor (corresponding to a steering operation amount sensor in the claims) 15 that detects the current flowing through the coil of the reaction motor 18 . This current is used, for example, when estimating the disturbance torque. Additionally, it is used to determine whether the driver is gripping the steering wheel.

A steering mechanism 16 including the steering shaft 17 is provided with a steering electric motor mechanism (corresponding to an electric steering actuator in the claims) 21 . to control. Although an electric motor is used as the steering electric actuator, it goes without saying that other types of electric actuators may be used.

The rotation angle sensor 14 of the reaction motor 18 detects the rotation angle of the steering wheel 12 and the current sensor 15 detects the current flowing through the coil. Various detection signals are also input to the controller 19 from an external sensor 20 .

The controller 19 calculates a control amount for the steering electric motor mechanism 21 based on the input rotation angle information and current information, and further drives the steering electric motor mechanism 21 . Parameters other than the rotation angle information and the current information can be used as the control amount of the electric motor mechanism 21 for steering.

Rotation of the steering electric motor mechanism 21 rotates an output side pulley (not shown) of the steering mechanism 16 via a belt (not shown) from an input side pulley (not shown), and further rotates a steering nut (not shown). (not shown) steers the steered wheels 10 by axially stroking the steering shaft 16 . These configurations will be described later.

Further, the controller 19 calculates the control amount of the reaction force motor 18 based on the input rotation angle information and current information, rack position information detected by a rack position sensor described later, and the like. drive. Here, the rack position sensor detects the amount of movement of the steering shaft 17 from the reference position (neutral position), which is information equivalent to the steering angle of the steered wheels. It should be noted that parameters other than the rack position information, the rotation angle information, and the current information can be used as the control amount of the reaction force motor 18 .

Here, although the controller 19 is shown as one functional block in FIG. 1, it is separated into a reaction force actuator controller and a steering actuator controller, and both are connected via a communication line. A reaction force electric actuator controller is provided in the reaction force motor 18 , and a steering actuator controller is provided in the steering electric motor mechanism 21 .

The steering mechanism 16 is provided with the rack position sensor (corresponding to the steering amount sensor in the claims) 22 as described above, and the rack position sensor 22 detects the stroke amount of the steering shaft 17 in the axial direction. It detects the actual steering amount (steering angle) of the steered wheels 10 and outputs steering amount information. As the steering amount sensor, the rack position sensor 22 for detecting the stroke amount of the steering shaft 17 is shown. Sensors other than these that can detect the position (steering amount) of the steering shaft 17 fall under the category of steering amount sensors.

The steering mechanism 16 includes a steering shaft 17, a steering electric motor, a reduction mechanism, etc., but the mechanism for transmitting steering force from the steering electric motor to the steered wheels 19 is not limited to these.

Next, the configuration of the steering mechanism 16 will be described. FIG. 2 shows an axial cross section of the steering mechanism 16 .

Each component of the steering mechanism 16 includes a steering shaft accommodating portion 30 that axially movably accommodates the steering shaft 17 , and an axially intermediate portion of the steering shaft accommodating portion 30 that surrounds the steering shaft 17 . It is housed in a housing 32 composed of a speed reducer housing portion 31 and a speed reducer housing portion 31 . A speed reduction mechanism 33, which will be described later, is housed in the speed reducer housing portion 31. As shown in FIG.

The steering electric motor mechanism 21 has a steering electric motor 35 , a steering actuator controller 44 that drives the steering electric motor 35 , and a screw mechanism 36 that transmits the output of the steering electric motor 35 to the steering shaft 17 . ing. The electric motor for steering 35 has its rotation amount, rotation speed, etc. controlled by the steering actuator controller 44 in accordance with the amount of steering operation input to the steering wheel 12 by the driver. The steering electric motor 35 is hereinafter referred to as the steering motor 35 .

The screw mechanism 36 has a steering nut 37 and an output pulley 38 . The output pulley 38 has a cylindrical shape and is fixed to the steering nut 37 so as to be integrally rotatable. A cylindrical input pulley 39 is fixed to the drive shaft of the steering motor 35 so as to rotate integrally therewith. A belt 40 is wound between the output pulley 38 and the input pulley 39 . The input pulley 39 , the output pulley 38 and the belt 40 constitute the reduction mechanism 33 .

The steering nut 37 is formed in an annular shape so as to surround the steering shaft 17 and is provided rotatably with respect to the steering shaft 17 . A helical groove is formed in the inner circumference of the steering nut 37, and this groove constitutes a nut-side ball screw groove. A spiral groove is also formed on the outer circumference of the steering shaft 17, and this groove constitutes the steering shaft side ball screw grooves 17a and 17b.

With the steering nut 37 inserted into the steering shaft 17, a ball circulation groove is formed by the nut-side ball screw groove and the steering shaft-side ball screw grooves 17a and 17b. The ball circulation groove is filled with a plurality of metal balls, and when the steering nut 37 rotates, the balls move in the ball circulation groove, causing the steering shaft 17 to stroke the steering nut 37 in the longitudinal direction. work and move.

In this way, the steering actuator controller 44 controls the rotation amount, rotation direction, rotation speed, etc. of the steering motor 35, and operates the steering shaft 17 in accordance with the steering operation of the steering wheel 12, thereby steering the vehicle. can be done.

Although the steering mechanism 16 shown in FIG. 2 is mounted only on the front wheels of the vehicle, it can also be mounted on the rear wheels of the vehicle. Therefore, not only the front wheels of the vehicle but also the rear wheels can be steered by the steering motor 35 .

Next, FIG. 3 shows a schematic configuration of a control circuit for the reaction motor 18 and the steering motor 35 by the controller 19 shown in FIG. The controller 19 represents both the reaction force electric actuator controller and the steering actuator controller.

A reaction force motor 18 connected to the steering shaft 13 is provided with a rotation angle sensor 14 and a current sensor 15 , and the reaction force motor 18 is mechanically connected to the steering wheel 12 . The rotation angle sensor 14 is a sensor that detects the rotation angle of the reaction motor 18 , in other words, the rotation angle of the steering wheel 12 . The current sensor 15 is a sensor that detects the current flowing through the coil of the reaction motor 18 .

The current sensor 15 also serves as a sensor that determines whether the driver is gripping the steering wheel 12 (override state, which will be described later) or not. In this case, it is determined whether the driver is gripping the steering wheel 12 or not, based on the change in the peak of the vibration component detected by detecting the vibration component of the current. This will be discussed later.

Furthermore, in addition to the current sensor 15, it is possible to determine whether the driver is gripping the steering wheel 12 or not using the rotation angle information from the rotation angle sensor 14 and the torque information from the reaction motor 18. The point is that a sensor suitable for the system should be used.

The reaction motor 18 is an electric motor that applies steering reaction torque to the steering shaft 13 via a motor driver 23 controlled by the controller 19. The controller 19 receives inputs from the rack position sensor 22 and the rotation angle sensor 14. A steering reaction force torque including a damping torque, which will be described later, is applied to the steering shaft 13 .

The controller 19 also supplies a steering motor 35 mechanically connected to the steering shaft 17 via the motor driver 24 with a drive signal corresponding to information from the external steering command value, the rotation angle sensor 14, the current sensor 15, and the like. ing.

The controller 19 is supplied with rotation angle information from the rotation angle sensor 14, is supplied with current information from the current sensor 15, and further receives information on vehicle conditions affecting steering from running state sensors such as the vehicle speed sensor 25 and the yaw rate sensor 26. Driving state information is provided. Further, the controller 19 is provided with information on the movement position (corresponding to the amount of steering) of the steering shaft 17 from a rack position sensor 22 (see FIG. 2) attached in the middle of the housing 32 covering the steering shaft 17. .

Here, the rack position sensor 22 detects the position of the steering shaft 17. Since the steering shaft 17 is directly connected to the tie rod 11, the position information of the rack position sensor 22 is used to detect the position of the steering wheel 10. steering angle can be detected. Thus, the rack position sensor 22 functions as a steering angle detector for the steered wheels 10 .

In the following description, the rack position means the stroke amount of the steering shaft 17 or the steering amount, and also means the steering angle of the steerable wheels 10 . Accordingly, the terms are used interchangeably and have the same meaning.

The controller 19 also receives an external steering command value from an automatic steering system (ADAS system) 27 as external steering control means. The external steering command value is external steering command information calculated by the automatic steering system 27. When the vehicle deviates from the white line on the road by lane keeping control or when avoiding an obstacle, the steering mechanism 16 controls the steering wheel. to steer the Note that the present embodiment described below is an embodiment in which the automatic steering system executes lane keep control.

The controller 19 detects the rotation angle, the current, the rack position, and the running state quantity provided from the rotation angle sensor 14, the current sensor 15, the rack position sensor 22, the running state sensors 25 and 26, and the automatic steering system 27, and External steering command information and the like are taken in at a predetermined sampling period, and the detected information and the external steering command information taken in are appropriately combined to determine the steering amount to be applied to the steering shaft 17, and the steering motor 35 is operated to obtain this steering amount. A coil current to be energized is calculated, and a drive signal corresponding to the calculation result is given to the motor driver 24 .

Similarly, the controller 19 obtains the steering reaction force torque to be applied to the steering wheel 12 by appropriately combining the rotation angle, the current, the rack position, the detection information of the running state quantity, the external steering command information, and the like, and calculates the steering reaction force. A coil current to be applied to the reaction motor 18 to obtain torque is calculated, and a drive signal corresponding to the calculation result is given to the motor driver 23 .

Here, the controller 19 is equipped with a steering ratio variable system. The variable steering ratio system corresponds to one form of steering angle control using vehicle running state information. It should be adjusted accordingly.

Next, FIG. 4 shows the hardware configuration of the controller 19. As shown in FIG. In this embodiment, the reaction force actuator controller 42 is built in the reaction force motor 18 and the steering actuator controller 44 is built in the steering motor 35 . Incidentally, the reaction force actuator controller 42 and the steering actuator controller 44 can also be incorporated in a common housing 45 indicated by a dashed line and provided in separate structural members.

The reaction force actuator controller 42 has a reaction force actuator microprocessor 46 as a main component, and further has a communication circuit 47 . The reaction force actuator microprocessor 46 includes a CPU 48 as an arithmetic unit, a ROM 49 as a memory, a RAM 50, an EEPROM (flash ROM) 51, an A/D converter 52, a bus line 53, and the like.

The CPU 48 controls the reaction motor 18 by executing various programs stored in the ROM 49 . Therefore, the actions performed by the program can be viewed as control functions.

The ROM 49 stores various programs executed by the CPU 48 . Specifically, the ROM 49 stores a control program for executing motor control processing (reaction force control processing) for controlling the reaction force motor 18 . Furthermore, the ROM 49 stores a diagnostic program for diagnosing the reaction motor 18 . The control program and diagnostic program are for executing predetermined control functions and diagnostic functions by the CPU 48 .

The RAM 50 is used as a work area when the CPU 48 executes the control program, and temporarily stores data required in the process and processing results. Similarly, a diagnostic program is executed and the diagnostic result is temporarily stored as an error code.

The EEPROM 51 is a memory that can retain its memory contents even after power is cut off, and stores correction values unique to hardware and error codes after execution of diagnostic functions. Also, the A/D converter 52 has a function of converting analog detection information from an external sensor into digital information.

Next, the steering actuator controller 44 has a steering actuator microprocessor 54 as a main component and further includes a communication circuit 55 .

The steering actuator microprocessor 54 includes a CPU 56 as an arithmetic unit, a ROM 57 and a RAM 58 as memories, an EEPROM (flash ROM) 59, an A/D converter 60, a bus line 61, and the like.

The CPU 56 executes various programs stored in the ROM 57 to control the steering motor 35 . Therefore, the actions performed by the program can be viewed as control functions.

The ROM 57 stores various programs executed by the CPU 56 . Specifically, the ROM 57 stores a control program for executing motor control processing (steering control processing) for controlling the steering motor 35 . Further, the ROM 57 stores a diagnostic program for diagnosing the steering motor 35 . The control program and diagnostic program are for executing predetermined control functions and diagnostic functions by the CPU 56 .

The RAM 58 is used as a work area when the CPU 56 executes the control program, and temporarily stores data required in the process and processing results. Similarly, a diagnostic program is executed and the diagnostic result is temporarily stored as an error code.

The EEPROM 59 is a memory that can retain its memory contents even after the power is turned off, and stores hardware-specific correction values and error codes after execution of diagnostic functions. Also, the A/D converter 60 has a function of converting analog detection information from an external sensor into digital information.

Further, the reaction force actuator microprocessor 46 and the steering actuator microprocessor 54 are supplied from the rotation angle sensor 14, the current sensor 15, the rack position sensor 22, the running state sensors 25 and 26, and the automatic steering system 27, Rotation angle, current, rack position, detection information of running state quantity, external steering command value, etc. are taken in at a predetermined sampling period. Further, the control data calculated by the reaction force actuator microprocessor 46 and the steering actuator microprocessor 54 are mutually exchanged via the communication circuit 47 and the communication circuit 55 .

In the controller 19 as described above, the configuration of the control block of this embodiment for controlling the reaction force motor 18 and the steering motor 35 and the control flow corresponding to this control block will now be described.

Here, the control block shown in FIG. 5 and the control flow shown in FIGS. 10A and 10B treat the reaction force actuator controller 42 and the steering actuator controller 44 as one controller.

5, in this embodiment, at least vehicle speed information (Vs) from the vehicle speed sensor 25, rotation angle information (θm/steering operation amount) of the reaction force motor 18 from the rotation angle sensor 14 of the reaction force motor 18, reaction force Coil current information (Im) of the reaction motor 18 from the current sensor 15 of the motor 18, rack position information (Rp/steering amount) from the rack position sensor 22, and external steering command value (Adas) from the automatic steering system 27 is entered.

Here, in the active steer mode, the external steering command value from the automatic steering system 27 is the steering command value for lane keeping control, and is output when the vehicle deviates from the white line on the road. In the lane keeping control, the vehicle-mounted camera 62 captures an image of the white line laid on the road, and this image information is input to the automatic steering system (ADAS system) 27 . Then, the automatic steering system (ADAS system) 27 calculates steering angle information so that the vehicle does not deviate outside the white line, and the calculated steering angle information is received as an external steering command value (Adas) from an external steering command signal. It is sent to section 71 .

The steering torque command value generator 63 calculates the final steering torque command value to be applied to the electric steering actuator 64 , and the calculated final steering torque command value is sent to the pre-driver 65 of the electric steering actuator 64 . , the pre-driver 64 controls the MOSFET of the inverter 66 and the like to drive the steering motor 35 and, as a result, strokes the steering shaft 17 to steer the steered wheels 10 .

The steering torque command value generator 63 receives vehicle speed information (Vs) from the vehicle speed sensor 25, rack position information (Rp) from the rack position sensor 22, and rotation angle information ( .theta.m), etc. are input, and the final steering torque command value in the manual steering mode is obtained by arithmetically processing these information.

This final steering torque command value can be obtained by various calculations, and appropriate calculations can be performed according to the system. In this embodiment, the steering torque command value is basically determined by the rotation angle information (θm) of the reaction force motor 18, and various corrected steering torque command values are reflected in this basic steering torque command value. Then, the final steering torque command value is obtained.

Furthermore, the external steering command value (Adas) from the automatic steering system 27 received by the external steering command receiving unit 67 is also input to the steering torque command value generating unit 63, and this external steering command value is used to A final steering torque command value in the active steer mode is obtained, which enables lane keeping control.

For example, when an external steering command value is input from the automatic steering system 27 to avoid a collision, the steering torque command value obtained by adding the basic steering torque command value and the external steering command value is obtained as the final steering torque command value. be done.

Then, the final steering torque command value is sent to the pre-driver 65, which controls the MOSFET of the inverter 66 and the like to drive the steering motor 35. As a result, the steering shaft 17 is stroke-operated to move the steered wheels 10. steer.

Similarly, the steering reaction force torque command value generator 68 calculates the final steering reaction force torque command value to be applied to the reaction force electric actuator 69, and the calculated final steering reaction force torque command value is used as the reaction force torque command value. The signal is sent to the pre-driver 70 of the electric actuator 69 , and the pre-driver 70 controls the MOSFET of the inverter 71 and the like to drive the reaction motor 18 , and as a result rotates the steering shaft 13 to rotate the steering wheel 12 .

The steering reaction force torque command value generator 68 receives vehicle speed information (Vs) from the vehicle speed sensor 25, rack position information (Rp) from the rack position sensor 22, and rotation angle of the steering shaft 13 from the rotation angle sensor 14 of the reaction motor 18. Information (θm), current information (Im) flowing in the coil of the reaction motor 18 from the current sensor 15 of the reaction motor 18, etc. are input, and these information are arithmetically processed to obtain the final result in the manual steering mode. A steering reaction force torque command value is obtained.

This final steering reaction force torque command value can be obtained by various calculations, and appropriate calculations can be performed according to the system. In this embodiment, the rotation of the steering wheel 12 is determined based on at least the rotation angle information (θm/steering operation amount information) from the rotation angle sensor 14 and the rack position information (Rp/steering amount information) from the rack position sensor. In the direction opposite to the direction, the reaction force torque that gives resistance to the rotation of the steering wheel is obtained, and this is used as the basic steering reaction force torque command value. A damping torque command value, which will be described later, is reflected in this basic steering reaction force torque command value to obtain a final steering reaction force torque command value.

The final steering reaction force torque command value is sent to the pre-driver 70 , and the pre-driver 70 controls the MOSFET of the inverter 71 and the like to drive the reaction force motor 18 . In the active steer mode, the steering shaft 13 is rotated based on the rack position information (Rp) to match the rotational position of the steering wheel 12 with the steering angle of the steered wheels 10 .

Here, the steering reaction force torque command value generation unit 68 is provided with a steering mode determination unit 72 , and the coil current of the reaction force motor 18 is input from the current sensor 15 . This coil current contains vibration information of the steering wheel 12, and it can be determined whether the steering wheel 12 is being gripped by the driver or not.

FIG. 6 shows determination means for determining whether or not the override state exists. Note that the override means steering operation based on the driver's intention, that is, steering operation by the driver holding the steering wheel. Therefore, the manual steer mode is executed when in the override state, and the active steer mode is executed when the "hands off state" is not in the override state.

In FIG. 6, the current information from the current sensor 15 is converted into frequency information by a fast Fourier transform processing block (FFT) 75, and this frequency information is input to a bandpass filter (BPF) 76. FIG. Here, the pass frequency band of the bandpass filter (BPF) 76 does not include the resonance frequency around the steering wheel 12 in the "hands off state" and is set to a frequency band lower than this resonance frequency. That is, as shown in FIG. 7, the pass frequency band (Fbnd) is set to a frequency band that is lower than the first frequency and higher than the second frequency, which is lower than the resonance frequency in the hands-free state.

The steering wheel 12 vibrates slightly due to forces such as vehicle vibration and reaction force from the tires, and this is observed as current information. When the driver grips the steering wheel 12 and the moment of inertia around the steering wheel increases, the resonance frequency around the steering wheel 12 decreases.

FIG. 7 shows frequency information when the driver does not grip the steering wheel 12 and in an override state when the driver grips the steering wheel 12 . When the driver does not grip the steering wheel 12, the frequency information (Fn) is on the high frequency side, but when the driver grips the steering wheel 12, the frequency information (Fh) is on the low frequency side. are moving to

For this reason, the peak of the resonance frequency (Fh) in the override state moves to the side of the pass frequency band (Fbnd) of the bandpass filter (BPF) 76, so that the peak of the resonance frequency reaches the bandpass filter (BPF) 76 can be passed. The feature amount, which is the signal strength of the frequency component that has passed through the bandpass filter (BPF) 76, becomes large because it reaches the peak of the resonance frequency.

Conversely, if the peak of the resonance frequency (Fn) is out of the pass frequency band (Fbnd) as in the hands-free state, the feature amount, which is the signal strength of the frequency component that has passed through the bandpass filter (BPF) 76, becomes small. The characteristic shown on the lower side of FIG. 7 indicates the shielding rate of the frequency of the band-pass filter (BPF) 76, and it can be seen that the shielding rate is small in the pass frequency range of the band-pass filter (BPF) 76. Recognize.

Here, the feature value (index) that is the signal strength of the frequency component may be the signal strength obtained by adding all the energy of the frequency components in the pass frequency band (Fbnd), or the maximum energy of the pass frequency band (Fbnd). may be used as the signal strength.

The signal strength of the frequency component that has passed through the bandpass filter (BPF) 76 is input to the signal strength comparison block section 77 and compared with a predetermined strength comparison threshold (SL). Therefore, when the driver does not grip the steering wheel 12, the signal strength is small and does not exceed the strength comparison threshold (SL). The intensity comparison threshold (SL) will be exceeded.

Thus, when the signal strength of the resonance frequency exceeds the strength comparison threshold (SL), it can be determined that the overriding state exists. Although the override state is determined from the current information in this embodiment, the override state can also be determined from the rotation angle information of the rotation angle sensor and the torque information of the reaction motor in addition to the current information.

Returning to FIG. 5 , the mode determination result of the steering mode determining section 72 is sent to the steering mode switching section 73 . The steering mode switching section 73 switches between the active steering mode and the manual steering mode based on at least the override information from the steering mode determination section 72 . The active steering mode is a mode in which the electric steering actuator 35 is driven and controlled based on the external steering command value (Adas). In this mode, the steering electric actuator 35 is driven and controlled based on the current state.

Further, the switching information of the steering mode switching unit 73 is sent to the damping torque command value generation unit 74, which selects any one of the first damping torque command value, the second damping torque command value, and the third damping torque command value, The selected damping torque command value is sent to the steering reaction force torque command value generator 68 . Here, the magnitude of the damping torque command value is set to satisfy the relationship of "first damping torque command value>third damping torque command value>second damping torque command value".

A damping torque command value generation unit 74 generates a first damping torque command value when the steering mode switching unit 73 selects the active steering mode, and the mode switching unit 73 selects the manual steering mode. The second damping torque command value is generated when the

In addition, in an intermediate state between a state in which the driver holds the steering wheel 12 firmly and a state in which the driver completely releases the steering wheel 12, the damping torque command value is generated. The damping torque command value generated by the unit 74 is a third damping torque command value set to a magnitude between the first damping torque command value and the second damping torque command value. A damping torque command value suitable for the grip state can be generated.

Here, based on the rack position information (Rp) from the rack position sensor 22, the first damping torque command value in the active steering mode is based on the rotational speed of the steering wheel 12 when the steering wheel approaches the neutral position. This is damping torque information for driving and controlling the reaction force electric actuator 69 so as to generate torque for decelerating and pushing the steering wheel 12 back to the neutral position when the steering wheel 12 exceeds the neutral position.

The first damping torque command value is obtained by a first damping coefficient Kfd having characteristics as shown in FIG. A maximum damping coefficient Kfdmax, a gradually decreasing damping coefficient Kfddec, and a minimum damping coefficient Kfdmin are set symmetrically on the right turning side and the left turning side with respect to the rotation of the steering wheel 12 with respect to the neutral position. Therefore, the rotation angle information (θm) of the rotation angle sensor 14 is input to the damping torque command value generator 74 .

The damping torque is obtained by obtaining a basic damping torque from the rotation angle and rotation speed of the rotation angle sensor 14 and multiplying this damping torque by the first damping coefficient Kfd. In this embodiment, the first damping coefficient Kfd is set to a maximum damping coefficient Kfdmax that increases the damping torque over a range of a predetermined angle (+θ) on the right side and a predetermined angle (−θ) on the left side from the neutral position. ing.

In addition, the damping coefficient Kfd gradually decreases from the maximum damping coefficient Kfdmax, as indicated by the gradually decreasing damping coefficient Kfddec, and the minimum damping occurs when the motor is rotated by a predetermined angle (+θ) to the right side and a predetermined angle (−θ) to the left side. is the coefficient Kfdmin. The first damping coefficient Kfd is stored in a map or the like.

Thus, the first damping coefficient Kfd is set to a value that increases the damping torque as the steering wheel approaches the neutral position. , a torque is generated that pushes the steering wheel back to the neutral position. This can improve the convergence to the neutral position in the active steer mode.

On the other hand, the second damping torque command value in the manual steering mode is smaller than the first damping torque command value based on the rotation angle information (θm) from the rotation angle sensor 14, and damping torque information for driving and controlling the reaction force electric actuator so as to generate torque in the direction opposite to the steering-back direction.

The second damping torque command value is obtained by a second damping coefficient Ksd having characteristics as shown in FIG. The second damping coefficient Ksd is set to a value smaller than the first damping coefficient Kfd at all rotation angles of the steering wheel 12 .

Here, the second damping coefficient Ksd is set to have the same characteristics as the first damping coefficient Kfd. , the overshoot phenomenon of the steering wheel 12 is unlikely to occur, and it is possible to set the second damping coefficient Ksd to a substantially constant value.

Also, the damping torque in the manual steering mode is obtained by obtaining the basic damping torque from the rotation angle and rotation speed of the rotation angle sensor 14 and multiplying this damping torque by the second damping coefficient Ksd. This second damping coefficient Ksd is also stored in a map or the like.

As a matter of course, the fact that the second damping torque command value is smaller than the first damping torque command value means that the second damping torque command value is less than the first damping torque command value when compared in the same steering state. When comparing the first damping torque command value and the second damping torque command value in mutually different steering states, the second damping torque command value is always smaller than the first damping torque command value. does not mean

As described above, the second damping coefficient Ksd is set to a value smaller than the first damping coefficient Kfd set in the active steering mode, so that the damping torque in the direction of turning the steering wheel or in the direction of steering back becomes large. It is possible to suppress the overshoot, and improve the phenomenon that the driver feels a sense of incompatibility when operating the steering wheel.

The first damping torque command value is selected in the active steering mode, and the second damping torque command value is selected in the manual steering mode. It will be sent to the generator 68 . Of course, it goes without saying that the third damping torque command value may be selected in some cases. This third damping torque command value will be described later.

The steering reaction force torque command generating unit 68 generates a steering wheel 12 opposite to the rotating direction of the steering wheel 12 based on at least the rotation angle information (θm) from the rotation angle sensor 14 and the rack position information (Rp) from the rack position sensor 22 . direction to generate a steering reaction force torque command value that resists rotation of the steering wheel 12 .

Further, the steering reaction force torque command generation unit 68 adds the first damping torque command value, the second damping torque command value, or the third damping torque command value to the steering reaction force torque command value to obtain the final steering reaction force torque command value. is generated, and this final steering reaction force torque command value is given to the reaction force electric actuator 69 to drive and control the reaction force motor 18 .

By the way, when the external steering command receiving unit 67 receives external steering command information related to lane keeping control from the automatic steering system (external steering control means) 27 and the vehicle is traveling on a continuous turning road, the steered wheels 19 is held at a predetermined steering angle (holding steering angle) corresponding to the turning road. Therefore, since the steering wheel 12 is rotated toward this holding steering angle, it is necessary to converge the steering wheel 12 to a rotational position different from the neutral position of the first damping coefficient Kfd.

For this purpose, it is effective to move the first damping coefficient Kfd toward the holding steering angle (steering holding position) of the steering wheel 12 that matches the holding steering angle of the steered wheels 10 . That is, as shown in FIG. 9, the first damping coefficient Kfd is moved to the left or right turning side to match the median value of the maximum damping coefficient Kfdmax in FIG. If the first damping torque command value is generated by using the steering wheel 12, the steering wheel 12 can be quickly converged to the holding steering angle.

That is, the damping torque command value generation unit 74 sets a steering holding position determined based on the steering angle of the steered wheels 10, sets this steering holding position as the neutral position of the steering wheel 12, and generates the first damping torque command. I am trying to generate a value. Here, the steering angle (holding position) varies depending on the curvature of the turning road and the traveling direction such as left turning or right turning. It is also possible to change the rudder holding position).

In this way, when the external steering command information related to lane keeping control is received from the automatic steering system (external steering control means) 27 and the vehicle is traveling on a continuous turning road, the steering angle of the steering wheel 12 is maintained. By moving the first damping coefficient Kfd toward the steering position), the steering wheel 12 can be quickly converged to the steering holding position.

Next, a control flow corresponding to the control blocks described above will be described with reference to FIGS. 10A and 10B. It should be noted that this control flow explains the technical concept of the present embodiment, and since there are various methods for actual control calculations and the like, the explanation is limited to a general description here. Also, this control flow is executed at a time-periodic start timing, for example, a 10 ms time interrupt.

<<Step S10>>
In step S10, various sensors detect operating parameters representing the operating state of the steering control device. In this embodiment, at least the vehicle speed information (Vs), the rotation angle information of the reaction force motor 18 (θm/steering operation amount information), the rack position information (Rp/steering amount information), the coil current information of the reaction force motor 18 ( Im), and an external steering command value (Adas) are detected. Of course, other operating parameters can be detected if desired. When the necessary operating parameters are detected, the process proceeds to step S11.

<<Step S11>>
In step S11, it is determined whether an external steering command value (Adas) relating to lane keep control is input from the automatic steering system (ADAS system) 27 or not. When an external steering command value (Adas) is input and it is determined that lane keep control is being performed, the process proceeds to step S11, and when it is determined that lane keep control is not being performed, the process proceeds to step S16.
<<Step S12>>
When it is determined in step S11 that the external steering command value (Adas) is input and lane keep control is being executed, in step S12 it is determined whether the road on which the vehicle is traveling is a turning road. do. This determination can be made based on the image of an on-vehicle camera provided in the automatic steering system (ADAS system) 27 or the map information of the navigation system. If it is determined that the vehicle is traveling on the turning road, the process proceeds to step S13, and if it is determined that the vehicle is traveling on the straight road instead of the turning road, the process proceeds to step S16.

<<Step S13>>
If it is determined in step S12 that the vehicle is traveling on a turning road, then in this step the vehicle is traveling on a right turning road where the vehicle turns to the right or a left turning road where the vehicle turns to the left. to determine whether the vehicle is running. This determination can also be made based on the image of the on-board camera provided in the automatic steering system (ADAS system) 27 and the map information of the navigation system to determine whether the road is a left-right turning road.

The process proceeds to step S14 when it is determined that the vehicle is traveling on the right-turning road, and the process proceeds to step S15 when it is determined that the vehicle is traveling on the left-turning road.

<<Step S14>>
In step S14, it is determined that the vehicle is traveling on a right-turning road, so as shown in FIG. Move to rudder position. The steering holding position can be determined based on the steering angle of the steered wheels 10 . Further, since the map information of the navigation system stores the curvature of the turning road, it is possible to determine the steering holding position based on this curvature.

This first damping coefficient Kfd is used when calculating the first damping torque in step S18, which will be described later. When the median value of the first damping coefficient Kfd is moved to the steering holding position on the right side of the neutral position, the process proceeds to step S16.

<<Step S15>>
On the other hand, in step S15, since it is determined that the vehicle is traveling on the left-turning road, as shown in FIG. Move to the rudder holding position. In this case also, the steering holding position can be determined based on the steering angle of the steered wheels 10 . Similarly, since the map information of the navigation system stores the curvature of the turning road, the steering holding position can be determined based on this curvature.

This first damping coefficient Kfd is used when calculating the first damping torque in step S18, which will be described later. When the median value of the first damping coefficient Kfd is moved to the left steering holding position with respect to the neutral position, the process proceeds to step S16.

From step S11 to step S15, during lane keeping control, damping control can be performed using the first damping torque value even when the driver is gripping the steering wheel 12. The behavior of the vehicle can be stabilized even with respect to the operation. Note that the lane keep control may perform steering control so that the vehicle does not deviate from the travel lane, or may perform steering control so that the vehicle travels along the travel lane.

If the steering system is to be simplified, or if control for shifting the median value of the first damping coefficient Kfd to the right or left is unnecessary, the control steps from step S11 to step S15 can be omitted. After completing the process of step S14 or step S15, the process proceeds to step S16.

<<Step S16>>
In step S16, it is determined whether or not the steering wheel 12 is in a "hands-off state" in which the driver does not grip it. This judgment can be made by the method shown in FIGS. Whether or not the steering wheel 12 is held by the driver is determined in step S26, which will be described later.

When the driver does not hold the steering wheel 12, the frequency information of the current sensor 15 is on the high frequency side, but when the driver holds the steering wheel 12, the frequency information moves to the low frequency side. do.

Therefore, the feature quantity, which is the signal intensity of the frequency component of the resonance frequency (Fh) in the overriding state that has passed through the bandpass filter (BPF) 76, includes the peak of the resonance frequency and thus becomes large. Conversely, if the peak of the resonance frequency (Fn) is out of the pass frequency band (Fbnd) as in the hands-free state, the feature amount, which is the signal strength of the frequency component that has passed through the bandpass filter (BPF) 76, becomes small.

Then, the signal strength obtained based on the frequency information that has passed through the bandpass filter (BPF) 76 is input to the signal strength comparison block unit 77, and as shown in FIG. ). Therefore, when the driver does not grip the steering wheel 12 and is in a "hands off state", the signal strength is small and does not exceed the first strength comparison threshold (SL1). , the signal strength is large and exceeds the first strength comparison threshold (SL1).

Note that the first strength comparison threshold (SL1) set in step S16 is set to a value that can reliably determine a "hands off state" in which the driver is not gripping the steering wheel 12. FIG. For example, when the driver is lightly gripping the steering wheel 12, the first strength comparison threshold (SL1) is exceeded because the driver is not in a "hands off state." If the steering wheel 12 is being gripped, including the state in which the steering wheel 12 is being lightly gripped, the determination is entrusted to step S26, which will be described later.

If the signal intensity of the frequency component that has passed through the bandpass filter (BPF) 76 is equal to or greater than the first intensity comparison threshold (SL1), it is determined that the signal is not in the "hands-off state", and the process proceeds to step S21. If the signal strength of the frequency component that has passed through the (BPF) 76 is less than the first strength comparison threshold value (SL1), it is determined that the device is in a "hands off state", and the process proceeds to step S17.

Here, in steps S11 to S16, the external steering command receiving unit receives the external steering command value, and in a region where the vibration frequency of the current information from the current sensor 15 is equal to or lower than a predetermined frequency, The active steer mode is selected when the signal strength of the frequency component of the current information from is less than a first strength comparison threshold (SL1). Therefore, the active steering mode can be reliably selected.

<<Step S17>>
In step S17, since the active steering mode is determined, the steering torque command value is generated based on the external steering command value (Adas) for automatic steering from the automatic steering system (ADAS system) 27. Output to the steering motor 35 .

The steering motor 35 automatically drives the vehicle by driving the steered wheels 10 to a predetermined steering angle based on an external steering command value (Adas). Automated driving can include lane keeping control and automated driving control. When the steering torque command value is generated and output to the steering motor 35, the process proceeds to step S18.

<<Step S18>>
In step S18, the first damping coefficient Kfd based on the current rotation angle information (θm) of the rotation angle sensor 14 is obtained from the characteristic map of the first damping coefficient Kfd shown in FIG. Since the rotation angle information (θm) of the rotation angle sensor 14 is substantially equivalent to the steering angle of the steered wheels 10 (excluding the rack position), the steering angle of the steered wheels can also be used.

Then, the basic damping torque command value is multiplied by the first damping coefficient Kfd read from the characteristic map to generate the first damping torque command value.

As described above, when traveling in the active steer mode, the steered wheels 10 are steered based on the external steering command value (Adas). Following this, the steering wheel 12 is also controlled to return to the neutral position.

Therefore, the first damping coefficient Kfd is set to a value that increases the damping torque as the steering wheel 12 approaches the neutral position. When it exceeds, a torque is generated that pushes the steering wheel back to the neutral position. This can improve the convergence to the neutral position in the active steer mode.

In this step, the first damping torque command value is generated by multiplying the basic damping torque command value by the first damping coefficient Kfd. It may be stored in a map and directly obtained. When the first damping torque command value is obtained, the process proceeds to step S19.

<<Step S19>>
In the active steering mode, the steered wheels 10 are steered based on the external steering command value (Adas), and the steering wheel 12 is rotated so as to follow this. Therefore, in step S19, the steering reaction force torque command value of the reaction force motor is obtained from the rack position information (Rp), and the first damping torque command value obtained in step S18 is added to this to obtain the final steering reaction force torque command. find the value. When the final steering reaction force torque command value is obtained, the process proceeds to step S20.

<<Step S20>>
In step S20, the final steering reaction force torque command value obtained in step S19 is output to the reaction force motor 18 to apply the steering reaction force torque to the steering shaft.

In this case, the first damping torque command value is set to a value that increases the damping torque as the steering wheel 12 approaches the neutral position. When the position is exceeded, a torque is generated that returns the steering wheel to the neutral position. This can improve the convergence to the neutral position in the active steer mode.

When the final steering reaction force torque command value is output to the reaction force motor 18 and the steering reaction force torque is applied to the steering shaft, the system exits to return and waits for the next start timing.

<<Step S21>>
In the determination processing of step S16, if the signal strength of the resonance frequency exceeds the first strength comparison threshold (SL1), it is determined that the override state is present and the manual steering mode is selected. However, in the judgment in step S16, even when the driver is lightly gripping the steering wheel 12, it is also judged as the manual steering mode, so it is difficult to detect the driver's intention to actively steer the steering wheel 12. .

Therefore, in step S21, it is determined whether or not the current value of the reaction motor is equal to or greater than a predetermined current value. When the driver grips the steering wheel 12 and actively steers, the current value based on the current feedback control of the reaction motor 18 increases. It can be determined that the wheel 12 is gripped firmly and the steering is executed.

For example, in the active steer mode in steps S17-S19, the reaction motor 18 rotates the steering wheel 12 to follow the movement of the steered wheels 10, which movement is controlled by an external steering command. corresponds to the value. In this active steer mode, when the driver grips the steering wheel 12 and performs a steering operation, there is a high possibility that the current information of the reaction force motor 18 will differ from that corresponding to the external steering command value. By judging the difference between the two, it is possible to judge the intervention of the driver's steering operation.

If the current value flowing through the reaction force motor 18 is equal to or greater than the predetermined current value in step S21, it is determined that the driver is in the manual steering mode in which the steering wheel 12 is securely gripped and the steering operation is performed, and the process proceeds to step S22. .

On the other hand, if the current value flowing through the reaction force motor 18 is not equal to or greater than the predetermined current value, it is determined that the driver is only lightly gripping the steering wheel 12, and the process proceeds to step S25.

<<Step S22>>
In step S22, since the manual steering mode is determined, a steering torque command value is generated based on the rotation angle information (.theta.m) and output to the steering motor 35. FIG.

The steering motor 35 controls the vehicle by driving the steered wheels 10 to a predetermined steering angle based on the rotation angle information (θm). When the steering torque command value is generated and output to the steering motor 35, the process proceeds to step S23.

<<Step S23>>
In step S23, the second damping coefficient Ksd based on the current rotation angle information (θm) of the rotation angle sensor 14 is obtained from the characteristic map of the second damping coefficient Ksd shown in FIG. Then, the basic damping torque command value determined from the rotation angle and rotation speed of the rotation angle sensor 14 is multiplied by the second damping coefficient Ksd read from the characteristic map to generate the second damping torque command value.

The second damping torque command value in the manual steering mode is smaller than the first damping torque command value based on the rotation angle information (θm) from the rotation angle sensor 14, and the steering wheel turning direction and steering back. Direction is the torque in the opposite direction. When the second damping torque command value is obtained, the process proceeds to step S24.

<<Step S24>>
In manual steering mode, the steering wheel 12 indirectly steers the steered wheels 10 . Therefore, in step S24, the steering reaction force torque command value of the reaction motor is obtained from the rotation angle information (θm) from the rotation angle sensor of the reaction force motor 18, and the second damping torque command value obtained in step S23 is added to this. is added to obtain the final steering reaction force torque command value. When the final steering reaction force torque command value is obtained, the process proceeds to step S20.

As described above, in step S20, the final steering reaction force torque command value obtained in step S24 is output to the reaction force motor 18 to apply the steering reaction force torque to the steering shaft. When the final steering reaction force torque command value is output to the reaction force motor 18 and the steering reaction force torque is applied to the steering shaft, the system exits to return and waits for the next start timing.

Since the second damping coefficient Ksd is set to a value smaller than the first damping coefficient Kfd set in the active steering mode, excessive damping torque in the steering wheel 12 turning direction and steering back direction can be prevented. It can be suppressed, and the phenomenon that the driver feels a sense of incongruity in operating the steering wheel can be improved.

Here, when switching between the active steering mode in steps S16 to S19 and the manual steering mode in steps S21 to S24, the active steering mode is switched to the manual steering mode. In the process of transition or in the process of transitioning from the manual steering mode to the active steering mode, the value of the damping coefficient changes significantly, so there is concern that the steering operation of the steering wheel 12 may feel uncomfortable during the transition process. be.

Therefore, as shown in FIG. 11A, when the active steering mode is switched to the manual steering mode, in the transition mode between the first damping coefficient Kfd and the second damping coefficient Ksd, the damping coefficient is It is effective to set a gradually decreasing transition damping coefficient K(f−S)d to transition from the first damping coefficient Kfd to the second damping coefficient Ksd.

By setting the transition damping coefficient K(fs)d in this way, the damping torque command value is gradually reduced from the first damping torque command value to approach the second damping torque command value. It is possible to reduce the switching shock when switching from the first damping torque command value to the second damping torque command value, and improve the steering operation feeling.

Further, as shown in FIG. 11B, when the manual steering mode is switched to the manual steering mode, the damping coefficient gradually increases in the transition mode between the second damping coefficient Ksd and the first damping coefficient Kfd. to transition from the second damping factor Ksd to the first damping factor Kfd by setting the transition damping factor K(s−f)d that gradually increases to .

By setting the transition damping coefficient K(s-f)d in this manner, the damping torque command value is gradually increased from the second damping torque command value to approach the first damping torque command value. , the switching shock when switching from the second damping torque command value to the first damping torque command value can be reduced, and the steering operation feeling can be improved. Furthermore, it is possible to reduce the vibration of the steering wheel due to sudden changes in the steering reaction force torque of the reaction force motor 18 .

Returning to FIG. 10B again, if it is determined in step S21 that the current value flowing through the reaction force motor 18 is not equal to or greater than the predetermined current value, the control steps after step S25 are executed. The determination in step S21 is based on the assumption that the driver is holding the steering wheel 12 but not performing a steering operation (including a state in which the driver is only putting his or her hand on the steering wheel 12).

<<Step S25>>
In step S25, it is determined whether or not the rotation speed of the rotation angle sensor 14 of the reaction motor 18 is equal to or higher than a predetermined value. The reason for executing this step S25 is to observe whether or not the rotation speed has increased by the driver steering the steering wheel 12 .

Therefore, when it is determined that the rotation speed is increasing as a result of the driver's steering operation of the steering wheel 12, it is assumed that the manual steering mode is set and the process proceeds to step S22. It should be noted that, including the determination result of step 26 to be described below, the case of moving to step S22 has already been described, so a repeated description will be omitted.

On the other hand, if it is determined that the rotation speed has not increased, it is determined that the driver is gripping the steering wheel 12 but not steering, and the process proceeds to step S26.

<<Step S26>>
In step S26, the signal strength of the frequency component that has passed through the bandpass filter (BPF) 76 is compared with a predetermined second strength comparison threshold (SL2) in the same manner as in step S16. The second strength comparison threshold (SL2) is set to a value that allows the driver to reliably grasp the steering wheel 12. The second strength comparison threshold (SL1) < second strength comparison threshold (SL2)”.

FIG. 12 shows the relationship between the first intensity comparison threshold (SL1) and the second intensity comparison threshold (SL2). When the driver is not holding the steering wheel 12, the signal strength of the frequency component passing through the bandpass filter (BPF) 76 is smaller than the first strength comparison threshold (SL1).

On the other hand, when the driver firmly grips the steering wheel 12, the signal strength of the frequency component passing through the bandpass filter (BPF) 76 is greater than the second strength comparison threshold (SL2).

When the driver grips the steering wheel 12 lightly and does not steer, the signal strength of the frequency component passing through the bandpass filter (BPF) 76 is the first strength comparison threshold (SL1) and the second strength It becomes a value between the comparison thresholds (SL2).

Therefore, when the signal strength of the frequency component that has passed through the bandpass filter (BPF) 76 is equal to or greater than the second strength comparison threshold (SL2), it is determined that the steering wheel 12 is securely held by the driver. In order to execute the manual steering mode, the process proceeds to step S22.

On the other hand, if the signal strength of the frequency component that has passed through the band-pass filter (BPF) 76 is less than the second strength comparison threshold (SL2), the driver is holding the steering wheel 12 with his/her hand but not gripping it firmly. , the steering operation is not performed, and the process proceeds to step S27 to execute the active steering mode.

<<Step S27>>
In step S27, since the active steering mode is determined, the steering torque command value is generated based on the external steering command value (Adas) for automatic steering from the automatic steering system (ADAS system) 27. Output to the steering motor 35 .

The steering motor 35 automatically drives the vehicle by driving the steered wheels 10 to a predetermined steering angle based on an external steering command value (Adas). Automated driving can include lane keeping control and automated driving control. When the steering torque command value is generated and output to the steering motor 35, the process proceeds to step S28.

<<Step S28>>
In step S28, the third damping coefficient Ktd based on the current rotation angle information (θm) of the rotation angle sensor 14 is obtained from the characteristic map of the third damping coefficient Ktd shown in FIG. Since the rotation angle information (θm) of the rotation angle sensor 14 is substantially equivalent to the steering angle of the steered wheels 10 (excluding the rack position), the steering angle of the steered wheels can also be used. Then, the basic damping torque command value is multiplied by the third damping coefficient Ktd read from the characteristic map to generate the third damping torque command value.

Here, as can be seen from FIG. 8, the third damping coefficient Ktd is set to satisfy the relationship of "first damping coefficient Kfd>third damping coefficient Ktd>second damping coefficient Ksd". When the third damping torque command value is obtained, the process proceeds to step S29.

<<Step S29>>
In the active steering mode, the steered wheels 10 are steered based on the external steering command value (Adas), and the steering wheel 12 is rotated so as to follow this. Therefore, in step S29, the steering reaction force torque command value of the reaction force motor 18 is obtained from the rack position information (Rp), and the third damping torque command value obtained in step S18 is added to this to obtain the final steering reaction force torque. Find the command value. When the final steering reaction force torque command value is obtained, the process proceeds to step S20.

As described above, in step S20, the final steering reaction force torque command value obtained in step S24 is output to the reaction force motor 18 to apply the steering reaction force torque to the steering shaft. When the final steering reaction force torque command value is output to the reaction force motor 18 and the steering reaction force torque is applied to the steering shaft, the system exits to return and waits for the next start timing.

In this way, if it is determined in step S26 that the driver is not holding the steering wheel 12 firmly with his/her hand and is not in a state of steering operation, the active steering mode is assumed. ing. Since the driver is holding the steering wheel 12 with his or her hand, the steering wheel 12 wobbles at the neutral position (overshoot phenomenon) even if a large damping torque such as the first damping torque command value is not applied. Therefore, a damping torque command value suitable for the driver's grip on the steering wheel 12 can be obtained.

As described above, in the present invention, in the active steering mode such as automatic driving control, by driving the reaction force motor based on the first damping torque command value having a relatively large damping torque, The convergence of the steering wheel can be improved. Further, in the manual steering mode in which the steering wheel is operated, by driving the reaction force motor based on the second damping torque command value having a damping torque smaller than the first damping torque command value, the driver can control the steering wheel. It is possible to suppress the feeling of discomfort in operating the .

In addition, the present invention is not limited to the above-described embodiment, and includes various modifications. For example, the above-described embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. Also, part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Moreover, it is possible to add, delete, or replace part of the configuration of each embodiment with another configuration.

Reference Signs List 10 Steering wheel 12 Steering wheel 13 Steering shaft 14 Reaction motor rotation angle sensor (steering operation amount sensor) 15 Reaction motor current sensor (steering operation amount sensor) 17 Steering shaft 18 ... Reaction force electric motor 19 ... Control device 22 ... Rack position sensor (steering amount sensor) 27 ... Automatic steering system 35 ... Steering electric motor 62 ... In-vehicle camera 63 ... Steering torque command value generator, 64 Steering electric actuator 67 External steering command receiving unit 68 Steering reaction torque command value generating unit 69 Reaction electric actuator 72 Steering mode determining unit 73 Steering mode switching unit 74 Damping torque command value generator.

Claims (12)

a steering operation shaft that is rotatable with the rotation of the steering wheel of the vehicle and that is mechanically separated from the steered wheels;
a reaction force electric actuator that applies a steering reaction torque to the steering operation shaft;
a steering electric actuator that generates a steering force for steering the steered wheels;
a steering member that transmits a steering force of the steering electric actuator to the steered wheels;
a steering operation amount sensor that detects a steering operation amount of the steering wheel and outputs steering operation amount information regarding the steering operation amount;
a steering amount sensor that detects the steering amount of the steered wheels and outputs steering amount information regarding the steering amount;
A steering comprising control means for driving and controlling the electric actuator for reaction force and the electric actuator for steering based on at least steering operation amount information from the steering operation amount sensor and steering amount information from the steering amount sensor. a controller,
The control means includes at least an external steering command receiving section, a steering mode switching section, a damping torque command value generating section, and a steering reaction force torque command value generating section,
The external steering command receiving unit receives external steering command information generated by the external steering control means based on information on the roadway of the vehicle or information on the driving situation of the vehicle,
The steering mode switching unit switches between an active steering mode and a manual steering mode at least based on steering operation amount information from the steering operation amount sensor, and the active steering mode is switched between the external steering command a mode in which the electric steering actuator is driven and controlled based on information, and the manual steering mode is a mode in which the electric steering actuator is driven and controlled based on the steering operation amount information;
The damping torque command value generating section generates a first damping torque command value when the steering mode switching section selects the active steering mode, and the steering mode switching section selects the manual steering mode. Generate a second damping torque command value when selecting
The first damping torque command value is set based on the steering amount information from the steering amount sensor so as to generate torque in the direction of returning the steering wheel to the neutral position when the steering wheel exceeds the neutral position. Damping torque information for driving and controlling the electric force actuator,
The second damping torque command value is smaller than the first damping torque command value, and the steering operation amount information from the steering operation amount sensor in a direction opposite to the turning direction and the steering back direction of the steering wheel. Damping torque information for driving and controlling the reaction force electric actuator so as to generate a torque based on
The steering reaction force torque command value generation unit generates a torque in a direction opposite to the rotating direction of the steering wheel based on at least the steering operation amount information from the steering operation amount sensor and the steering amount information from the steering amount sensor. generating a steering reaction force torque command value that gives resistance to rotation of the steering wheel, and reflecting the first damping torque command value or the second damping torque command value in the steering reaction force torque command value to make a final A steering control device for generating a steering reaction force torque command value, and for driving and controlling said reaction force electric actuator according to said final steering reaction force torque command value. The steering control device according to claim 1,
The steering operation amount sensor is a current sensor that detects a coil current of a reaction force electric motor that constitutes the reaction force electric actuator,
The steering mode switching unit switches between the active steering mode and the manual steering mode based on the output value of the current information in a region where the frequency component of the current information from the current sensor is equal to or lower than a first frequency. A steering control device characterized by: The steering control device according to claim 2,
The steering mode switching unit switches the manual mode when the signal strength of the frequency component of the current information from the current sensor is equal to or higher than a first strength comparison threshold in a region where the frequency component of the current information is equal to or lower than the first frequency. - A steering control device characterized by selecting a steer mode. The steering control device according to claim 3,
The damping torque command value generation unit, in a frequency band region in which the frequency component of the current information from the current sensor is equal to or less than the first frequency and equal to or greater than a second frequency lower than the first frequency,
generating the first damping torque command value when the signal strength of the frequency component of the current information is smaller than the first strength comparison threshold;
generating the second damping torque command value when the signal strength of the frequency component of the current information is greater than a second strength comparison threshold that is greater than the first strength comparison threshold;
generating a third damping torque command value when the signal strength of the frequency component of the current information is between the first strength comparison threshold and the second strength comparison threshold;
The first damping torque command value, the second damping torque command value, and the third damping torque command value are
"First damping torque command value > Third damping torque command value > Second damping torque command value"
A steering control device characterized by being set in a relationship of The steering control device according to claim 2,
The steering mode switching unit is configured to be active when the signal strength of the frequency component of the current information from the current sensor is less than a first strength comparison threshold in a region where the frequency component of the current information is equal to or lower than the first frequency. - A steering control device characterized by selecting a steer mode. The steering control device according to claim 2,
The steering mode switching unit controls the current flow in a region in which the external steering command receiving unit receives the external steering command information and the frequency component of the current information from the current sensor is equal to or lower than a first frequency. A steering control device, wherein the active steering mode is selected when an output value of the current information from a sensor is less than a first intensity comparison threshold. The steering control device according to claim 1,
The steering operation amount sensor is a rotation angle sensor that outputs rotation speed information of the steering wheel,
When the steering mode switching unit selects the active steer mode, the steering reaction force torque command value generation unit generates the steering reaction force torque command value corresponding to the external steering command information,
When the active steering mode is selected, the steering mode switching unit continues the active steering mode or performs the manual steering based on the external steering command information and the rotation speed information. A steering control device characterized by switching modes. The steering control device according to claim 1, wherein
The steering control device, wherein the damping torque command value generator increases the first damping torque command value as the steering wheel approaches a neutral position. The steering control device according to claim 1, wherein
When the steering mode switching unit switches from the active steering mode to the manual steering mode, the damping torque command value generation unit converts the first damping torque command value to the second damping torque command value A steering control device characterized by gradually decreasing a damping torque command value toward . The steering control device according to claim 1, wherein
When the steering mode switching unit switches from the manual steering mode to the active steering mode, the damping torque command value generation unit converts the second damping torque command value to the first damping torque command value. A steering control device characterized by gradually increasing a damping torque command value toward . The steering control device according to claim 1, wherein
When the external steering command receiving unit receives the external steering command information related to lane keep control from the external steering control means,
The steering control device, wherein the damping torque command value generator generates the first damping torque command value regardless of whether the steering wheel is held by a driver. A steering control device according to claim 11, wherein
The damping torque command value generation unit increases the first damping torque command value as the steering wheel approaches a neutral position,
When the external steering command receiving unit receives the external steering command information related to the lane keep control from the external steering control means and the vehicle is turning on a turning road,
The damping torque command value generator sets a steering holding position determined based on the steering angle of the steered wheels, sets this steering holding position as the neutral position of the steering wheel, and generates the first damping torque command value. A steering control device characterized by generating

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