WO2020184853A1 - Apparatus for overlay control of electric power steering system, and method therefor - Google Patents

Abstract

Provided are an apparatus for overlay control of an electric power steering system, and a method therefor. The apparatus for overlay control of an electric power steering system according to an embodiment of the present invention comprises: a first overlay controller for controlling the output torque of a motor in a first overlay mode according to a target angle; and a second overlay controller for controlling the output torque of the motor in a second overlay mode according to a target torque, wherein after a command to release one overlay mode is issued and before the corresponding overlay mode is ended, when the other overlay mode is started, the controller for the overlay mode being released boosts the speed at which the output of the overlay mode is released.

Description

Overlay control device and method for electric power steering system

The present invention relates to an electric power steering system, and more particularly, to an apparatus and method for controlling an overlay of an electric power steering system capable of performing a smooth transition between an angle overlay and a torque overlay.

Recently, assistance systems for providing convenience and safety to drivers provide various functions. This assistance system is called ADAS (Advanced Driver Assistance System). In particular, ADAS provides convenience functions to a driving user by interlocking with an Electric Power Steering (EPS) system.

Among the ADAS functions linked to the electric power steering system, the Lane Keeping Assist (LKA) function is aimed at preventing lane departure, and operates while the driver grips the steering wheel. This does not require precise tracking compared to the autonomous driving function, and operates in the driver's steering mode, so it uses a torque overlay method that is relatively advantageous in terms of heterogeneity to the driver.

In addition, since the autonomous driving function requires precise tracking in preparation for the lane keeping function, the angle overlay method is used.

In recent years, as additional functions applied to vehicles such as autonomous driving have been expanded, there is an increasing demand to simultaneously apply an angle overlay and a torque overlay. However, since the angle overlay and the torque overlay have different control methods, a problem may occur during driving due to a sense of heterogeneity or lack of control following performance when switching modes.

In order to solve the problems of the prior art as described above, an embodiment of the present invention provides an overlay control apparatus and method for an electric power steering system capable of preventing a decrease in response performance when switching between an angle overlay and a torque overlay. It has its purpose.

However, the problem to be solved by the present invention is not limited to the problems mentioned above, and other problems that are not mentioned will be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention for solving the above problems, the first overlay controller for controlling the output torque of the motor in the first overlay mode according to the target angle; And a second overlay controller that controls the output torque of the motor in a second overlay mode according to the target torque, and when the other overlay mode is started before the termination after the release command of any one overlay mode, the The controller in the overlay mode being released is provided with an overlay control device of the electric power steering system that increases the output release speed.

In an embodiment, the increased output release speed may be the same regardless of the start time of the other overlay mode.

In an embodiment, the increased output release speed may be different according to the start time of the other overlay mode.

In an embodiment, the increased output release speed may be different according to a difference between a release time of one of the overlay modes and a start time of the other overlay mode.

In an embodiment, the apparatus for controlling an overlay of the electric power steering system includes: an ADAS (Advanced Driver Assistance system) controller that transmits the target angle or the target torque to the first and second overlay controllers according to a driving setting; It may further include.

In an embodiment, the ADAS controller may control start, release, and end of the first and second overlay modes.

In an embodiment, the apparatus for controlling an overlay of the electric power steering system may further include a summer for summing output torques of the first and second overlay controllers.

According to another aspect of the present invention, the method includes: controlling an output torque of a motor in a first overlay mode according to a target value of any one of a target angle and a target torque; Determining whether there is an operation request for controlling the output torque of the motor in a second overlay mode according to another target value before the end of the first overlay mode; And increasing an output release speed of the first overlay mode when there is a request for the operation before termination after the release command of the first overlay mode. The method for controlling an overlay of an electric power steering system is provided.

In an embodiment, in the step of increasing the output release speed, the increased output release speed may be set to be the same regardless of the start time of the second overlay mode.

In an embodiment, in the step of increasing the output canceling speed, the increased output canceling speed may be set to be different according to the start time of the second overlay mode.

In an embodiment, in the step of increasing the output release speed, the increased output release speed may be set to be different according to a difference between a release time of the first overlay mode and a start time of the second overlay mode.

The overlay control apparatus and method of the electric power steering system according to an embodiment of the present invention increase the output release speed of the overlay mode that ends when the overlay mode is switched, thereby smoothly switching between overlay modes. It is possible to ensure stable performance during mode switching by preventing a decrease in responsiveness that may occur during switching.

1 is a schematic configuration diagram of an electric power steering system according to an embodiment of the present invention,

2 is a block diagram of an overlay control apparatus of an electric power steering system according to an embodiment of the present invention;

3 is a timing diagram of an output torque when switching an overlay mode in an overlay control device of an electric power steering system according to an embodiment of the present invention;

4 is a timing diagram of an output torque when the angle overlay mode is released in the overlay control device of the electric power steering system according to an embodiment of the present invention, and,

5 is a flowchart of an overlay control method of an electric power steering system according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art can easily implement the present invention. The present invention may be implemented in various different forms, and is not limited to the embodiments described herein. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and the same reference numerals are assigned to the same or similar components throughout the specification.

The embodiments of the present invention are provided to more completely describe the present invention to those of ordinary skill in the art, and the embodiments described below may be modified in various different forms, and The scope is not limited to the following examples. Rather, these examples are provided to make the present invention more faithful and complete, and to fully convey the spirit of the present invention to those skilled in the art.

1 is a schematic configuration diagram of an electric power steering system according to an embodiment of the present invention.

Referring to FIG. 1, the electric power steering system 10 according to an embodiment of the present invention includes a steering wheel 11, a steering shaft 12, a sensor 13, an EPS motor 14, and an electronic control unit 15. ), rack-pinion gear (16) and wheels (17).

The steering wheel 11 may be connected to the EPS motor 14 through the steering shaft 12. The sensor 13 is installed on the steering shaft 12 to detect a rotation angle of the steering wheel 11 and a torque according to the rotation of the steering wheel 11, respectively. Here, the sensor 13 may be a combination of a torque sensor and an angle sensor or a single torque angle sensor.

The electronic control unit 15 is an ECU (electronic control unit) and may control the EPS motor 14 to be driven according to a target value by a set ADAS function. At this time, the electronic control unit 15 may estimate a target value while detecting the rotational state of the steering wheel 11 from the sensor 13.

For example, the electronic control unit 15 may control the EPS motor 14 to perform a torque overlay mode or an angle overlay mode. In this case, the electronic control unit 15 may control to be smoothly switched when the overlay mode is switched, as described later. That is, the electronic control unit 15 may include the overlay control device 100 of FIG. 2.

The EPS motor 14 drives the rack-pinion gear 16 through a universal joint. At this time, the steering of the wheel 17 may be performed through the rack bar according to the driving of the rack-pinion gear 16.

2 is a block diagram of an apparatus for controlling an overlay of an electric power steering system according to an embodiment of the present invention.

The overlay control device 100 may control the EPS motor 14 to perform a torque overlay or an angle overlay to perform a function for assisting driving. The overlay control device 100 may be implemented by the electronic control unit 15, and includes an ADAS controller 110, a first overlay controller 120, a second overlay controller 130, and a summer 140. can do.

The ADAS controller 110 may control the electric power steering system 10 to perform a driving assistance function. At this time, the ADAS controller 110 transmits a target value to the first and second overlay controllers 120 and 130 according to the driving setting performed by the driving assistance function.

Here, the ADAS controller 110 transmits the target angle θ to the first overlay controller 120 in the first overlay mode, and transfers the target torque T to the second overlay controller 130 in the second overlay mode. I can deliver.

The ADAS controller 110 may control start, release, and end of the first and second overlay modes. That is, the ADAS controller 110 may control the first and second overlay controllers 120 and 130 to operate in the corresponding mode.

The first overlay controller 120 controls the output torque of the EPS motor 14 in the first overlay mode according to the target angle θ. Here, the first overlay mode may be an angle overlay mode. For example, the first overlay controller 120 may control the EPS motor 14 in an angle overlay mode during autonomous driving.

The second overlay controller 130 controls the output torque of the EPS motor 14 in a second overlay mode according to the target torque T. Here, the second overlay mode may be a torque overlay mode. For example, the second overlay controller 130 may control the EPS motor 14 from the lane maintenance mode to the torque overlay mode.

In this case, when switching from one overlay mode to another overlay mode, the first overlay mode and the second overlay mode may operate simultaneously. For example, when the second overlay mode is started before the end of the first overlay mode after a command to cancel the first overlay mode, the first and second overlay modes may operate simultaneously.

For example, during autonomous driving, the overlay control device 100 operates in an angle overlay mode. That is, the first overlay controller 120 may drive the EPS motor 14. Here, the driver does not control the steering wheel 11.

In this case, there may be a case of switching to the lane keeping mode during autonomous driving. For example, when a failure of a CAN signal related to the angle overlay mode occurs, the angle overlay is suddenly released, and the vehicle may leave the lane while driving. Since this can cause an accident, it can automatically switch to lane keeping mode to prevent this.

That is, when switching to the torque overlay mode while operating in the angle overlay mode, the angle overlay mode and the torque overlay mode may operate simultaneously.

Here, the controller in the overlay mode being released increases the output release speed. For example, the first overlay controller 120 receiving the release command may increase the output release speed so that the first overlay mode ends quickly when the second overlay mode is started.

3 is a timing diagram of an output torque when switching an overlay mode in an overlay control apparatus of an electric power steering system according to an embodiment of the present invention, and FIG. 4 is an overlay control apparatus of an electric power steering system according to an embodiment of the present invention. It is a timing diagram of the output torque when the angle overlay mode is released.

Here, a case of switching from the angle overlay mode to the torque overlay mode is described as an example, but is not limited thereto. That is, the same can be applied to the case of switching from the torque overlay mode to the angle overlay mode.

Referring to FIG. 3, when a mode release command occurs while the angle overlay mode is being executed, the ramp down is performed from the time when the release command is issued (S1) to the end time (T4) of the corresponding overlay mode in order to eliminate the feeling of operation heterogeneity -down). That is, the output torque decreases to 0 (Nm) at a constant speed.

In addition, when the start command of the torque overlay mode is generated, the start command is ramped up from the time when the start command is generated (S2) to the time when the target value is achieved (T5) in order to eliminate the sense of heterogeneity in the operation. That is, the output torque increases to the target torque value (2Nm) at a constant speed.

On the other hand, when the torque overlay mode is started before the end of the angle overlay mode after the angle overlay mode is released, the angle overlay output torque and the torque overlay output torque are generated together in the interval T2 to T4. Here, the motor output torque is represented by the sum of the angle overlay output torque and the torque overlay output torque.

At this time, the ramp-down of the angle overlay and the ramp-up of the torque overlay are performed at the same speed. That is, the slope of the angle overlay output torque and the slope of the torque overlay output torque are the same. Therefore, in the overlay mode overlapping section (T2 to T3), the sum of the angle overlay output torque and the torque overlay output torque becomes constant. This section acts as a delay in tracking output torque, resulting in performance degradation in the overlay operation.

In order to solve this problem, the present invention increases the output release speed of the canceled overlay mode so as to follow the target torque value of the immediately switched overlay mode without causing a delay section.

That is, at the start time (S2) of the torque overlay mode, the first overlay controller 120 that is canceling the angle overlay mode increases the output canceling speed. Here, as shown in the lower graph of FIG. 3, the slope (dotted line) of the angle overlay output torque increases, so that the angle overlay mode is canceled more quickly to the time point T3.

In this case, in the overlay mode overlapping period (T2 to T3), the motor output torque follows the target value from the start time (S3) of the torque overlay mode. Here, in the overlay mode overlapping section (T2 to T3), since the release speed of the angle overlay output torque increases, the sum of the angle overlay output torque and the torque overlay output torque increases.

In addition, only the torque overlay mode is performed after the time point T3 when the angle overlay mode is completely ended. That is, the motor output torque of FIG. 3 follows the target value with a slope such as an intermediate graph.

Accordingly, since the delay section that occurs when switching the overlay mode is eliminated, it is possible to prevent a decrease in responsiveness when switching the overlay mode.

Referring to FIG. 4, the output torque of the angle overlay mode may be differently ramped down according to the start time of the torque overlay mode.

For example, when the torque overlay mode is started (S2) at the same time as the angle overlay mode is canceled (S1), the output canceling speed of the angle overlay mode is increased at the time point T1. That is, the slope of the angle overlay output torque increases at the time point T1. Therefore, the angle overlay mode is canceled faster to the point T3' than to the original point T4.

In addition, if the torque overlay mode is started (S2) after the angle overlay mode release command (S1) and before the angle overlay mode ends (S2), the output release speed of the angle overlay mode increases at the time T2. That is, the slope of the angle overlay output torque increases at a point in time T2 between T1 and T4. Therefore, the angle overlay mode is canceled faster to the time point T3 than to the time point T4.

In addition, when the torque overlay mode is started after the end of the angle overlay mode, it ends at the output release speed of the preset angle overlay mode. That is, the slope of the angle overlay output torque (solid line) does not change. Therefore, the angle overlay mode ends at the original time point T4.

In this case, the output release speed increased by the start of the torque overlay mode may be the same regardless of the start time of the torque overlay mode. That is, as shown in FIG. 4, the increased ramp-down slope (dotted line, double-dashed line) of the angle overlay output torque may be the same as the start time of the torque overlay mode.

Alternatively, the power release speed increased by the start of the torque overlay mode may be different depending on the start time of the torque overlay mode. That is, the increased rampdown slope of the angle overlay output torque may be different according to the start time of the torque overlay mode.

In this case, the output release speed increased by the start of the torque overlay mode may be different according to a difference between the release time S1 of the angle overlay mode and the start time S2 of the torque overlay mode. For example, as the start time S2 of the torque overlay mode approaches the release time S1 of the angle overlay mode, the output release speed may increase to a greater degree. Here, when the start time S2 of the torque overlay mode and the release time S1 of the angle overlay mode are the same, the output release speed may increase the largest. That is, the ramp-down slope of the torque overlay output torque may be maximum.

Referring back to FIG. 2, the summer 140 may add up the output torques of the first and second overlay controllers 120 and 130. Here, when switching between the first overlay mode and the second overlay mode, both the first and second overlay controllers 120 and 130 are output torques T1 and T2 until immediately before the end after a command to release any one of the overlay modes. ) Occurs. In this case, the summer 140 sums the output torque T1 of the first overlay controller 120 and the output torque T2 of the second overlay controller 130 and outputs the sum to the EPS motor 14.

With such a configuration, since the overlay control apparatus 100 can smoothly perform switching between overlay modes, it is possible to prevent a decrease in responsiveness that may occur when switching the overlay mode, thereby ensuring stable performance during mode switching.

Hereinafter, an overlay control method of the electric power steering system of the present invention will be described with reference to FIG. 5. 5 is a flowchart of an overlay control method of an electric power steering system according to an embodiment of the present invention.

The method 200 for controlling the overlay of the electric power steering system includes performing a first overlay mode (S210, S220), starting a second overlay mode while terminating the first overlay mode (S230 to S250), and a second overlay. It includes performing the mode (S260, S270) and terminating the overlay (S280).

In more detail, as shown in FIG. 5, first, the overlay control apparatus 100 determines whether to operate in the first overlay mode (step S210), and when not operating in the overlay mode, when operating the overlay mode. Wait until.

As a result of the determination in step S210, when it is determined that the device operates in the first overlay mode, the overlay control apparatus 100 performs the first overlay mode (step S220). Here, the first overlay mode controls the output torque of the EPS motor 14 according to the target angle. For example, the overlay control device 100 may perform an operation in an angle overlay mode according to autonomous driving.

Next, the overlay control apparatus 100 determines whether to end the first overlay mode (step S230), and if it is determined that the first overlay mode is not to be terminated, the first overlay mode is continuously performed while waiting.

As a result of the determination in step S230, when it is determined that the first overlay mode is to be terminated, the overlay control apparatus 100 commands the output of the first overlay mode to be released. That is, the ramp-down of the first overlay mode output torque is started.

At this time, the overlay control device 100 determines whether to operate the second overlay mode (step S240). That is, before the end of the first overlay mode, it is determined whether there is an operation request for controlling the output torque of the EPS motor 14 in the second overlay mode.

As a result of the determination in step S240, when it is determined that the second overlay mode is to be operated, the overlay control apparatus 100 starts the second overlay mode (step S250). Here, the second overlay mode controls the output torque of the EPS motor 14 according to the target torque. As an example, the overlay control apparatus 100 may start the torque overlay mode when switching to the lane keeping mode due to a failure during autonomous driving.

At this time, the first overlay mode is not completely released, and the output torque is ramping down by the release command. That is, since the second overlay mode is started before the first overlay mode is completely terminated, this is a section in which the first and second overlay modes overlap. In addition, the second overlay mode is a state in which ramp-up is performed at a constant speed from the time when the start command is generated to the target torque value.

Next, the overlay control device 100 increases the output cancellation speed of the first overlay mode (step S260). That is, when the second overlay mode is started before the end after the release command of the first overlay mode, the output release speed of the first overlay mode is increased so that the first overlay mode is quickly terminated.

In this case, the overlay control apparatus 100 may set the output release speed increased by the start of the second overlay mode to be the same regardless of the start time of the second overlay mode. For example, as illustrated in FIG. 4, the increased ramp-down slope of the angle overlay output torque may be the same regardless of the start time of the second overlay mode.

Alternatively, the overlay control apparatus 100 may set the output release speed increased by the start of the second overlay mode to be different according to the start time of the second overlay mode. That is, the increased rampdown slope of the angle overlay output torque may be different according to the start time of the second overlay mode.

In this case, the overlay control apparatus 100 may set the output release speed increased by the start of the second overlay mode to be different according to a difference between the release time of the first overlay mode and the start time of the second overlay mode. For example, in FIGS. 3 and 4, as the start time S2 of the torque overlay mode approaches the release time S1 of the angle overlay mode, the output release speed may increase significantly. Here, when the start time S2 of the torque overlay mode and the release time S1 of the angle overlay mode are the same, the output release speed may increase the largest. That is, the ramp-down slope of the torque overlay output torque may be maximum.

Next, the overlay control apparatus 100 performs a second overlay mode (step S270). In this case, the first overlay mode may be completely ramped down and terminated. Therefore, only the second overlay mode can be performed. Here, the second overlay mode is ramped up to the target value for a predetermined time, and then the EPS motor 14 may be controlled with the target torque.

As a result of the determination in step S240, when it is determined that the second overlay mode is not operated, the first overlay mode is ended and all overlay operations are ended (step S280).

By this method, since the overlay control method 200 can smoothly perform switching between overlay modes, it is possible to ensure stable performance during mode switching by preventing a decrease in responsiveness that may occur when switching overlay modes.

Such methods can be implemented by the overlay control device 100 as shown in Fig. 2, and in particular, can be implemented as a software program that performs these steps, in this case, these programs are computer-readable recording. It may be stored in a medium or transmitted by a computer data signal combined with a carrier wave in a transmission medium or a communication network.

In this case, the computer-readable recording medium includes all kinds of recording devices in which data readable by a computer system is stored, for example, ROM, RAM, CD-ROM, DVD-ROM, DVD-RAM, magnetic tape, It may be a floppy disk, a hard disk, or an optical data storage device.

Although an embodiment of the present invention has been described above, the spirit of the present invention is not limited to the embodiment presented in the present specification, and those skilled in the art who understand the spirit of the present invention can add components within the scope of the same idea Other embodiments may be easily proposed by changes, deletions, additions, etc., but it will also be said to fall within the scope of the present invention.

Claims (11)

A first overlay controller controlling an output torque of the motor in a first overlay mode according to a target angle; And Including; a second overlay controller for controlling the output torque of the motor in a second overlay mode according to the target torque, The overlay control device of the electric power steering system for increasing the output release speed when the other overlay mode is started before the end after the release command of one of the overlay modes. The method of claim 1, The increased output release speed is the same as the overlay control device of the electric power steering system regardless of the start time of the other overlay mode. The method of claim 1, The increased output release speed is different from the overlay control device of the electric power steering system according to the start time of the other overlay mode. The method of claim 3, The increased output release speed is an overlay control device of an electric power steering system different from a difference between a release time of one of the overlay modes and a start time of the other overlay mode. The method of claim 1, An overlay control device for an electric power steering system further comprising: an ADAS (Advanced Driver Assistance system) controller for transmitting the target angle or the target torque to the first and second overlay controllers according to a driving setting. The method of claim 5, The ADAS controller is an overlay control device of an electric power steering system that controls start, release, and end of the first and second overlay modes. The method of claim 1, An overlay control device for an electric power steering system further comprising a summer for summing output torques of the first and second overlay controllers. Controlling an output torque of the motor in a first overlay mode according to one of a target angle and a target torque; Determining whether there is an operation request for controlling the output torque of the motor in a second overlay mode according to another target value before the end of the first overlay mode; And And increasing an output release speed of the first overlay mode when there is a request for the operation before termination after the release command of the first overlay mode. The method of claim 8, The step of increasing the output canceling speed comprises setting the increased output canceling speed to be the same regardless of the start time of the second overlay mode, the overlay control method of the electric power steering system. The method of claim 8, In the step of increasing the output release speed, the increased output release speed is set to be different according to the start time of the second overlay mode. The method of claim 10, In the step of increasing the output release speed, the increased power release speed is set to be different according to a difference between a release time of the first overlay mode and a start time of the second overlay mode.

Images