JP7312074B2 - Rudder angle control device - Google Patents

Description

The present invention relates to a technique for complementing the steering angle of a steering object such as a steering wheel of a vehicle.

Conventionally, when a vehicle is parked, an electric power steering motor (EPS motor) in an electric power steering device is used to automatically steer the steering wheel to guide the vehicle to a predetermined parking position. Parking assistance devices have been proposed that provide assistance. For example, Patent Literature 1 listed below discloses a parking assist device that suppresses an increase in the number of times of steering even when the steering torque of the electric power steering is small.

An electric power steering apparatus detects a steering torque of a steering wheel with a torque sensor, and an EPS-ECU (Electric Power Steering Electronic Control Unit) drives an EPS motor to generate an auxiliary torque corresponding to the detected steering torque. In addition, in the parking assist function (automatic parking assist), the electric power steering apparatus steers the steering wheel by generating torque with the EPS motor even if the driver does not operate the steering wheel. At this time, a target steering angle for parking assistance is output from the camera ECU to the EPS-ECU, and the output of the EPS motor is controlled by the EPS-ECU so as to achieve this target steering angle.

JP 2019-147481 A

In this way, the automatic steering in the parking assist function is performed by the EPS-ECU controlling the EPS motor based on the "target steering angle" instructed by the camera ECU, and being notified by the steering angle sensor as motor control feedback. The "current steering angle" is read and used for control.

By the way, in the electric power steering system, a brushless motor capable of supplying a large amount of current is often used. In an electric power steering apparatus using a brushless motor, an electric power steering electronic control unit (EPS-ECU) itself that controls the EPS motor can grasp the steering angle of the steering wheel.

On the other hand, the parking assistance function of a compact car often does not require a large torque, and in some cases a relatively low-power brushed motor is used. Here, an electric power steering apparatus using a motor with a brush is configured to detect a steering angle using a steering angle sensor. The steering angle sensor is provided with at least two gears, a main gear on the steering wheel side and a sub gear on the steering angle detection circuit side, and there is a gap called backlash between the main gear and the sub gear. is provided.

In automatic steering, when the steering direction is changed, such as when turning the steering wheel, the steering angle sensor may enter the dead zone due to the backlash, and the current steering angle R2′ detected by the steering angle sensor may not change ( See Figure 6). Since the motor current continues to be calculated toward the target steering angle during this period, the motor current is calculated in accordance with the current steering angle R2' after passing through the dead zone region. Reference E1), there is a problem that the automatic steering will hunt. As a result, there is a problem that the behavior of the vehicle is slightly affected, or that the driver feels uncomfortable through the steering wheel.

As described above, when a motor with a brush is employed, there is a problem caused by hunting when passing through the dead zone region. However, there is also a strong demand to reduce costs by adopting brushed motors, which are less expensive than brushless motors.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a steering angle control apparatus that employs a motor with a brush to reduce costs and to improve problems such as hunting caused by the dead zone region.

A steering angle control device of the present invention provided to solve the above-described problems comprises a motor with a brush that applies torque to a steered object; a steering angle sensor that detects a current steering angle of the steered object as a current steering angle; a control device for controlling the brushed motor, the steering angle sensor comprising a plurality of gears, the steering angle sensor having a backlash between at least two of the gears, the A dead zone area is formed in which a change in the steering angle of the steering target cannot be detected, and the control device performs a dead zone area detection process for detecting the dead zone area, and on the condition that the dead zone area is detected, Based on the amount of torque fluctuation in the dead zone, the amount of change in the steering angle in the dead zone is derived as the steering angle fluctuation, and the estimated current steering angle is derived by adding the steering angle fluctuation to the current steering angle. An estimated current steering angle derivation process and an update process of updating the estimated current steering angle derived by the estimated current steering angle derivation process as the current steering angle can be executed, and the current steering angle updated by the update process can be executed. The current value of the motor with brush can be controlled based on the steering angle.

According to the steering angle control device of the present invention, it is possible to suppress abrupt changes in the motor current after passing through the dead zone region while suppressing costs by using a motor with a brush. As a result, the steering angle control device of the present invention can achieve both cost reduction and improvement of the problem caused by hunting at the same time.

Further, if the steering angle control device of the present invention is used as an automatic steering device (electric power steering device) for a vehicle, when the steering wheel is turned back during automatic steering, a sense of discomfort caused by hunting after passing through the dead zone region can be eliminated. can be reduced.

A steering angle control device of the present invention provided to solve the above-described problems comprises a motor with a brush that applies torque to a steered object; a steering angle sensor that detects a current steering angle of the steered object as a current steering angle; a control device for controlling the brushed motor, the steering angle sensor comprising a plurality of gears, the steering angle sensor having a backlash between at least two of the gears, the A dead zone area is formed in which a change in the steering angle of the steering target cannot be detected, and the control device performs a dead zone area detection process for detecting the dead zone area, and on the condition that the dead zone area is detected, A complementary update process of adding or subtracting a predetermined value to or from the current steering angle to derive a corrected current steering angle and updating the corrected current steering angle as the current steering angle can be executed. The current value of the motor with brush can be controlled based on the updated current steering angle.

According to the steering angle control device of the present invention, it is possible to suppress rapid changes in the motor current after passing through the dead zone region while suppressing costs by using a motor with a brush. As a result, the steering angle control device of the present invention can achieve both cost reduction and improvement of the problem caused by hunting at the same time.

Further, if the steering angle control device of the present invention is used as an automatic steering device (electric power steering device) for a vehicle, when the steering wheel is turned back during automatic steering, a sense of discomfort caused by hunting after passing through the dead zone region can be eliminated. can be reduced.

The steering angle control device of the present invention is used in an electric power steering device for a vehicle, and is characterized in that the object to be steered is a steering wheel.

According to the steering angle control device of the present invention, it is possible to suppress abrupt changes in the motor current after passing through the dead zone region while suppressing costs by using a motor with a brush. As a result, the steering angle control device of the present invention can achieve both cost reduction and improvement of the problem caused by hunting at the same time. Specifically, according to the steering angle control device of the present invention, it is possible to reduce discomfort caused by hunting after passing through the dead zone region when turning the steering wheel during automatic steering.

According to the present invention, it is possible to provide a steering angle control device that can reduce costs by adopting a motor with a brush and can improve problems such as hunting caused by the dead zone region.

1 is a schematic diagram showing a vehicle provided with a steering angle control device of the present invention; FIG. FIG. 2 is a conceptual diagram showing a dead zone region in the steering angle control device of FIG. 1; 2 is a flowchart showing steering angle control A performed by the steering angle control device of FIG. 1; 2 is a flowchart showing steering angle control B performed by the steering angle control device of FIG. 1; (a) is a diagram showing changes in the current value when the current steering angle is complemented by the steering angle control device of FIG. It is a figure which shows the numerical formula for demonstrating. FIG. 5 is a reference diagram showing changes in steering angle and current value in a conventional electric power steering device;

A steering angle control device 10 of the present invention will be described below with reference to the drawings. Further, in the following embodiments, an example in which the steering angle control device 10 is used in a vehicle 1 having a parking assist function (automatic parking assist) will be described.

FIG. 1 is a schematic diagram showing the configuration of a vehicle 1. As shown in FIG. As shown in FIG. 1, a vehicle 1 includes a steering wheel 2 (steering object), a steering angle sensor 12, an EPS motor 30 (motor with brush), a torque sensor 20, an EPS-ECU 4 (control device), a camera ECU 6, a photographing device 8, and a display 9 .

A steering angle control device 10 of the present invention comprises a steering angle sensor 12, an EPS motor 30 (motor with brush), a torque sensor 20, and an EPS-ECU 4 (control device).

The steering angle sensor 12 is a sensor that detects the steering angle of the steering wheel 2 . The steering angle sensor 12 detects the rotation angle (steering angle) of the steering wheel 2 from the neutral position.

In the following description, the actual steering angle of the steering wheel 2 is described as "actual steering angle R1", and the steering angle detected by steering angle sensor 12 is described as "current steering angle R2".

The steering angle sensor 12 takes a positive value when the steering wheel 2 is rotated in one direction with a neutral position of 0 [deg] (in this embodiment, when the steering wheel 2 is operated to the right), and when the steering wheel is in the other direction. (in this embodiment, the steering wheel 2 is turned to the left), the current steering angle R2 is detected as a negative value. Further, the current steering angle R2 detected by the steering angle sensor 12 is notified to the EPS-ECU 4.

In the steering angle control device 10 of this embodiment, the angular velocity is calculated from the current steering angle R2 detected by the steering angle sensor 12 and the time measured by the timer. The detected angular velocity is notified to the EPS-ECU 4 .

As shown in FIG. 2 , the steering angle sensor 12 includes a main gear 14 and a sub-gear 16 that meshes with the main gear 14 . The main gear 14 is a gear on the steering wheel 2 side, and the sub-gear 16 is a gear on the steering angle detection circuit side (not shown). The steering angle sensor 12 uses a steering angle detection circuit (not shown) to detect the current steering angle of the steering wheel 2 as the current steering angle R2 based on the rotation angle transmitted from the main gear 14 to the sub gear 16 .

As shown in FIG. 2, the steering angle sensor 12 has a dead zone region due to backlash C between the main gear 14 (the gear on the side of the steering wheel 2) and the sub-gear 16 (the gear on the side of the steering angle detection circuit). be. More specifically, when the steering direction of the steering wheel 2 is switched, the steering angle sensor 12 detects the actual steering angle of the steering wheel 2 when the main gear 14 and the sub-gear 16 are positioned to form the backlash C. Although the angle R1 is changing, the amount of change in the actual steering angle R1 is within the range of the gap of the backlash C. Therefore, there is a dead zone region in which the current steering angle R2 detected by the steering angle sensor 12 does not change. be.

That is, the steering angle sensor 12 forms a dead zone region in which the change in the steering angle of the steering wheel 2 cannot be detected due to the backlash C between the two gears. As will be described later, the steering angle control device 10 derives the amount of change in the steering angle of the steering wheel 2 in the dead zone as the steering angle fluctuation amount θ based on the amount of torque fluctuation in the dead zone.

Although the backlash C is formed between the main gear 14 and the sub-gear 16 in the present embodiment, the steering angle control device of the present invention is not limited to this. Specifically, in the steering angle control device of the present invention, when the steering angle sensor has a plurality of sub-gears, backlash may be formed between the sub-gears.

The EPS motor 30 (motor with brush) outputs torque for rotating the steering wheel 2 when the steering wheel 2 is automatically steered. The EPS motor 30 is a brushed motor. The EPS motor 30 outputs torque according to the magnitude of the motor current. The EPS motor 30 is controlled by the EPS-ECU 4 in terms of the direction in which the motor current is supplied, that is, the direction in which the EPS motor 30 is rotated clockwise or the direction in which the EPS motor 30 is rotated counterclockwise, and the current value. Torque sensor 20 detects steering torque applied to steering wheel 2 . The torque of EPS motor 30 is detected by torque sensor 20 and notified to EPS-ECU 4 .

The EPS-ECU 4 (control device) is an electronic control unit that controls automatic steering. The EPS-ECU 4 normally controls the EPS motor 30 and the like according to the operation of the steering wheel 2 by the driver. That is, the EPS-ECU 4 detects the steering wheel operation by the driver and drives the EPS motor 30 so as to assist rotation in the detected direction of operation. During parking assistance (during automatic steering), the EPS-ECU 4 receives a target steering angle R3 and the like from the camera ECU 6, and controls the current of the EPS motor 30 according to the target steering angle R3 to drive the EPS motor 30. FIG.

The camera ECU 6 is an electronic control unit for assisting parking, and is composed of a microcomputer having a CPU and a memory. The camera ECU 6 detects the state and position information of the vehicle 1 based on the information input from the photographing device 8 . The camera ECU 6 receives image data and video data from each camera (front camera, side camera, etc.) of the photographing device 8 and creates a bird's-eye view image. Then, control for parking assistance is performed based on signals input from various sensors such as the steering angle sensor 12 and signals related to operation details input by the driver.

For example, the camera ECU 6 detects a white line or the like indicating the parking position based on the information from the photographing device 8 . In addition, the camera ECU 6 creates an ideal trajectory for parking with respect to the parking position indicated by white lines, etc. is created and displayed on the display 9.

The photographing device 8 is composed of a camera for photographing an image around the vehicle 1 . The photographing device 8 is composed of cameras provided at a plurality of locations of the vehicle 1, such as a right side camera, a left side camera, a front camera, and a rear camera. Image data captured by each camera of the imaging device 8 is output to the camera ECU 6 .

The display 9 is configured by, for example, an LCD (liquid crystal display) and is installed in the center console portion of the vehicle 1 . Note that the display 9 is not limited to an LCD, and may be an organic EL display, a plasma display, or the like. Also, the installation position is not limited to the center console portion, and may be within a range that can be seen from the driver.

On the screen of the display 9, an instruction image for starting parking assistance (parking assistance start button) and the like are displayed as touch panel buttons. By operating buttons displayed on the screen of the display 9, the driver (or fellow passenger) can instruct the start of parking assistance or designate a target parking position.

When a driver or the like operates a button or the like displayed on the screen of the display 9, the touch panel reads the touch position and outputs a corresponding operation signal (user operation information). Further, the display 9 displays a bird's-eye view image based on an image signal input from the camera ECU 6 during parking assistance. A bird's-eye view image is an image displayed as if looking down from a virtual viewpoint above the vehicle 1 . Note that the display 9 may also be used as a display for a navigation system, DA (Display/Audio), or the like.

<Regarding steering angle control>
Next, steering angle control performed by the steering angle control device 10 of the present invention will be described with reference to FIGS. 3 and 4 and the like.

In parking assistance for the vehicle 1, first, the driver or fellow passenger issues an instruction to start parking assistance. Further, when a parking assistance request (user operation information) is detected, a steering angle command value corresponding to the target steering angle R3 is output from the camera ECU 6, and the steering angle sensor 12 detects the steering angle based on this steering angle command value. The current steering angle R2, the angular velocity, and the torque detected by the torque sensor 20 are taken into the EPS-ECU 4. FIG. Further, while the EPS-ECU 4 monitors the actual drive current of the EPS motor 30, a necessary motor current is applied to the EPS motor 30, the EPS motor 30 is automatically driven, the steering wheel 2 is steered, and the The vehicle 1 is guided to a predetermined parking position without steering the steering wheel 2. - 特許庁

In the vehicle 1, in automatic steering, a process of detecting a dead zone area (dead zone area detection process) and a process of complementing and updating the current steering angle (update process) are performed.

In the steering angle control, the EPS-ECU 4 of the steering angle control device 10 performs (A) estimated current steering angle derivation processing, and then performs update processing (steering angle control A).

<Steering angle control A>
In the steering angle control A, the amount of change in the steering angle in the dead band region is derived as the steering angle fluctuation amount θ based on the torque fluctuation amount in the dead band region, and is estimated by adding the steering angle fluctuation amount θ to the current steering angle R2. A process for deriving the current steering angle R4 (estimated current steering angle derivation process) is performed. As a result, the steering angle control device 10 can suppress a sudden change in the current of the EPS motor 30 after passing through the dead zone region when turning the steering wheel 2 or the like.

Hereinafter, each process performed by the steering angle control device 10 in the steering angle control A will be described with reference to FIG.

In step 1, the EPS-ECU 4 (steering angle control device 10) updates the value detected by the steering angle sensor 12 (steering angle sensor value) as the "current steering angle R2".

In step 2, the EPS-ECU 4 performs a process of determining whether or not it is in the dead zone area (dead zone detection process). The EPS-ECU 4 determines (1) that the deviation between the "current steering angle R2" and the "target steering angle R3" is equal to or less than a specified value, (2) that the "target steering angle R3" does not change, and (3) " All of (1) to (4) that "current steering angular velocity" is equal to or less than a specified value (0 [deg]/s in this embodiment), and (4) "motor current" is equal to or less than a specified value. is determined to be in the dead zone region when the condition of (1) is satisfied.

More specifically, (1) when the deviation between the "current steering angle R2" and the "target steering angle R3" is equal to or less than the specified value, the current steering angle R2 is approaching the target steering angle R3, This is the case when the steering wheel 2 is approaching the turning position.

In addition, (2) when there is no change in the "target steering angle R3", the steering wheel 2 is being operated smoothly with respect to the target steering angle, and an unexpected change in the direction of operation is required. This is the case when there is no

Furthermore, (3) the "current steering angular velocity" being equal to or less than the specified value and (4) the "motor current" being equal to or less than the specified value indicate the timing of switching the steering direction (timing of switching the steering wheel 2). , the current steering angle R2 is close to the target steering angle R3, and the vehicle 1 is starting to stop.

When the above conditions (1) to (4) are satisfied, the EPS-ECU 4 determines that it is immediately before the steering direction change timing in the automatic steering and that it is in the dead zone region. The EPS-ECU 4 shifts the process to step 3 when it is determined to be in the dead band region (step 2=Yes), and when it is determined not to be in the dead band region (step 2=No) goes to step 5.

In step 3, the EPS-ECU 4 calculates and derives the "estimated current steering angle R4" and performs processing for detecting the steering direction from the torque sensor 20 (estimated current steering angle derivation processing).

Specifically, the EPS-ECU 4 obtains the angular velocity (ω) based on the torque (T) detected by the torque sensor 20 (see FIG. 5(b)). As shown in FIG. 5(b), the angular velocity (ω) is calculated by referring to constant values such as inertia (J), friction coefficient (S), and friction force (D) in addition to torque (T). derived.

Further, as shown in FIG. 5B, the EPS-ECU 4 integrates the derived angular velocity (ω) to derive the steering angle fluctuation amount θ per time (the steering angle change amount in the dead zone region). Further, the EPS-ECU 4 derives a value obtained by adding the steering angle fluctuation amount θ to the current steering angle R2 as an "estimated current steering angle R4" (see FIG. 5(c)).

In step 4, the EPS-ECU 4 updates the "estimated current steering angle R4" derived in step 3 as the current steering angle R2.

In step 5, the EPS-ECU 4 controls the output of the EPS motor 30 based on the current steering angle R2 updated by the process of step 4, and applies it to automatic steering control (update process). In the automatic steering control, the EPS-ECU 4 monitors the drive current of the EPS motor 30 and applies the necessary motor current to the EPS motor 30, automatically driving the EPS motor 30 and steering the steering wheel 2. .

<Steering angle control B>
Next, a modification of the steering angle control (steering angle control B) performed by the steering angle control device 10 will be described with reference to FIG.

In the steering angle control B, on the condition that the dead zone region is detected, a fixed variable value M (predetermined value) is added or subtracted from the current steering angle R2 to derive a complementary current steering angle R5. A process (complementary update process) is performed to update R5 as the current steering angle R2. As a result, the steering angle control device 10 can suppress a sudden change in the current of the EPS motor 30 after passing through the dead zone region when turning the steering wheel 2 or the like.

The processing of step 10 in the steering angle control B is the same as the processing of step 1 in the steering angle control A. Further, the processing of step 11 in the steering angle control B (the processing of determining whether or not it is in the dead zone region) is the same as the processing of step 2 in the steering angle control A. Furthermore, the processing of step 13 in the steering angle control B is the same as the processing of step 5 in the steering angle control A. Therefore, in the following description of steering angle control B, the description of steps 10, 11, and 13 will be omitted, and the processing of step 12 will be described.

In step 12, the EPS-ECU 4 derives a value obtained by adding the fixed variable value M to the current steering angle R2 as the complementary current steering angle R5, and updates the complementary current steering angle R5 as the current steering angle R2 (complementary updating process). .

To be more specific. In the EPS-ECU 4, an angle (for example, 0.1 degree) corresponding to the amount of change due to the backlash C is stored as a predetermined fixed variable value M. The EPS-ECU 4 sets a value obtained by adding or subtracting the fixed variable value M to or from the current steering angle R2 as a complementary current steering angle R5 when it is determined that the current steering angle is in the dead zone. Further, the EPS-ECU 4 performs a process of updating the complementary current steering angle R5 as the current steering angle R2, and applies it to the automatic steering control in step 13.

As described above, the EPS-ECU 4 calculates a value corresponding to the amount of variation of the current steering angle R2 in the dead zone when the steering wheel 2 of automatic steering enters the dead zone due to the backlash C of the steering angle sensor 12. Correct and update the current steering angle R2.

The steering angle control device 10 can suppress hunting when the steering wheel 2 is turned back by performing the steering angle control A or the steering angle control B described above. More specifically, as shown in FIG. 5( a ), the steering angle control device 10 has a dead zone for the current steering angle R 2 ′ of the conventional electric power steering device in which the variation amount of the steering angle in the dead zone region is not complemented. The current steering angle R2 is updated by complementing the steering angle variation amount in the region.

As a result, compared with the current value (E1 in FIG. 5(a)) of the conventional electric power steering device, the steering angle control device 10 smoothes the change in the motor current after passing through the dead band region. (E2 in FIG. 5(a)). More specifically, when the steering angle control device 10 enters the dead zone region when turning the steering wheel 2, the current value of the EPS motor 30 is set to a positive value in order to turn the steering wheel 2 after exiting the dead zone region. When transitioning from a value to a negative value (or vice versa), the change in motor current can be smoothed.

As a result, the steering angle control device 10 can suppress hunting of the automatic steering after passing through the dead zone region. Moreover, according to the steering angle control device 10 , the influence of hunting on the behavior of the vehicle 1 can be reduced, and the driver's feeling of discomfort through the steering wheel 2 can be suppressed.

Furthermore, the steering angle control device 10 employs a motor with a brush as the EPS motor 30 to reduce costs.

Although the embodiments of the steering angle control device of the present invention have been described above, the steering angle control device of the present invention is not limited to the above-described embodiments.

Specifically, in the above-described embodiment, the steering angle control device 10 is used in an electric power steering device capable of automatic steering. may be used in other devices with

Further, the steering angle control device 10 of the above-described embodiment may be capable of executing both the steering angle control A and the steering angle control B. may be executable.

Furthermore, in the steering angle control device 10 of the above-described embodiment, the angular velocity is obtained based on the current steering angle R2 detected by the steering angle sensor 12. etc.) may be provided separately.

INDUSTRIAL APPLICABILITY The present invention can be suitably employed as one related to steering angle control of an object to be steered such as a steering wheel of a vehicle.

1 vehicle 2 steering wheel (steering object)
4 EPS-ECU (control device)
10 steering angle control device 12 steering angle sensor 14 main gear (gear)
16 sub gear (gear)
30 EPS motor (motor with brush)
C Backlash M Fixed variable value (predetermined value)
R2 Current steering angle R4 Estimated current steering angle R5 Complementary current steering angle θ Steering angle fluctuation amount

Claims (1)

a brushed motor that imparts torque to a steering target;
a steering angle sensor that detects a current steering angle of the steering target as a current steering angle;
a control device for controlling the brushed motor;
the steering angle sensor comprises a plurality of gears,
In the steering angle sensor, a dead zone region is formed in which changes in the steering angle of the steering target cannot be detected due to backlash between at least two of the gears,
The control device
a dead zone area detection process for detecting the dead zone area;
On the condition that the dead band region is detected, the amount of change in the steering angle in the dead band region is derived as the steering angle fluctuation amount based on the torque fluctuation amount in the dead band region, and the steering angle fluctuation amount is added to the current steering angle. an estimated current steering angle derivation process for deriving an estimated current steering angle by adding the amount;
an updating process of updating the estimated current steering angle derived by the estimated current steering angle deriving process as the current steering angle,
A steering angle control device, wherein the current value of the brushed motor can be controlled based on the current steering angle updated by the updating process.

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