Electronic Steering Control Device and Its Control Method

Abstract

The present disclosure provides an electronic steering control device that applies a redundant system and includes a first position controller and a second position controller. When communication is established between the first position controller and the second position controller, the first position controller can control the position of the first motor based on the commanded steering angles θ1 and θ2 from the control unit and the feedback steering angles θ m1 and θ m2 and the second position controller can control the position of the second motor based on the commanded steering angles θ1 and θ2 from the control unit and the feedback steering angles θ m1 and θ m2 The electronic steering control device can eliminate the offset accumulated between the two controllers of the dual MDPS system for autonomous driving.

Description

Technical Field

[0001] Exemplary embodiments of the present disclosure relate to an electronic steering control device and a control method thereof, and more particularly, to an electronic steering control device and a control method thereof that can remove an offset accumulated between two controllers of a dual MDPS (Motor Driven Power Steering) system for autonomous driving. Background Art

[0002] Generally, an electronic steering control device (e.g., an MDPS system) is applied to a vehicle, and the electronic steering control device ensures the stability of a steering state by reducing a steering force of a steering wheel.

[0003] Recently, technologies of electronic steering control devices applying a redundant system (i.e., a full redundant system) have been studied to prevent a control vacancy from occurring in a vehicle such as an autonomous driving vehicle (in which no driver intervention is performed), and to ensure the safety of a driver by continuously maintaining a steering force even when a failure occurs.

[0004] However, when a redundant system (i.e., a full redundant system) is introduced into an electronic steering control device (e.g., an MDPS system) for autonomous driving, one electronic steering control device is controlled by two position controllers (a first position controller and a second position controller). In this case, as an offset between position control signals accumulates, the control performance of the electronic steering control device may be somewhat degraded, making it difficult to normally perform position control.

[0005] In addition, as the offset accumulates, vibrations occur in the electronic steering control device (e.g., an MDPS system). In this case, the vehicle may not move along a desired steering path. As a result, autonomous driving may not be normally performed.

[0006] The related art of the present disclosure is disclosed in Korean Patent Application Publication No. 10-2017-0136765, published on December 12, 2017, and titled "Steering Control Apparatus and Steering Control Method, and Steering-State Determination Apparatus therefor". Summary of the Invention

[0007] Each embodiment relates to an electronic steering control device and a control method thereof, and the electronic steering control device can remove an offset accumulated between two controllers of a dualized MDPS (motor-driven power steering) system for autonomous driving.

[0008] In an embodiment, an electronic steering control device is provided, which applies a redundant system and includes a first position controller and a second position controller. When communication is established between the first position controller and the second position controller, the first position controller can control the position of the first motor according to command steering angles θ1 and θ2 from a control unit and feedback steering angles θ m1 and θ m2 from the motor, and the second position controller can control the position of the second motor according to command steering angles θ1 and θ2 from the control unit and feedback steering angles θ m1 and θ m2 from the motor.

[0009] When communication is established between the first position controller and the second position controller, the first position controller can calculate the average value of the command steering angles θ1 and θ2 and the average value of the feedback steering angles θ m1 and θ m2 and control the position of the first motor according to the calculated average value, and the second position controller can calculate the average value of the command steering angles θ1 and θ2 and the average value of the feedback steering angles θ m1 and θ m2 and control the position of the second motor according to the calculated average value.

[0010] When the communication between the first position controller and the second position controller is cut off, each of the first position controller and the second position controller can check as follows: when a position control error value corresponding to the difference between the command steering angle and the feedback steering angle falls within a first specific range, check whether the motor control current is equal to or greater than a first specific value; when the motor control current is equal to or greater than the first specific value, check whether the command steering angle, yaw rate, and lateral acceleration fall within a second specific range; and when the command steering angle, the yaw rate, and the lateral acceleration fall within the second specific range, check whether the position control error value is actually equal to or less than a second specific value.

[0011] Between the first position controller and the second position controller, in a case where a state in which the position control error value is equal to or less than the second specific value is maintained for a specified specific time, the corresponding position controller can reset all the position control error values accumulated so far.

[0012] After resetting the accumulated position control error value, the corresponding position controller can gradually increase the control gain in a ramp manner within a predetermined time.

[0013] The position control error value can be a position control error value filtered by considering errors outside the control frequency range caused by instantaneous disturbances or obstacles or potholes on the road.

[0014] In an embodiment, a control method for an electronic steering control device is provided. The electric steering control applies a redundant system and includes a first position controller and a second position controller device. The control method may include: when communication is established between the first position controller and the second position controller, the first position controller controls the position of the first motor according to the commanded steering angles θ1 and θ2 from the control unit and the feedback steering angles θ m1 and θ m2 from the motor; and the second position controller controls the position of the second motor according to the commanded steering angles θ1 and θ2 from the control unit and the feedback steering angles θ m1 and θ m2 from the motor.

[0015] When communication is established between the first position controller and the second position controller, the first position controller may calculate the average value of the commanded steering angles θ1 and θ2 and the average value of the feedback steering angles θ m1 and θ m2 and control the position of the first motor according to the calculated average value, and the second position controller may calculate the average value of the commanded steering angles θ1 and θ2 and the average value of the feedback steering angles θ m1 and θ m2 and control the position of the second motor according to the calculated average value.

[0016] The control method may further include: when the communication between the first position controller and the second position controller is cut off, when the position control error value corresponding to the difference between the commanded steering angle and the feedback steering angle falls within a first specific range, each of the first position controller and the second position controller checks whether the motor control current is equal to or greater than a first specific value; when the motor control current is equal to or greater than the first specific value, each of the first position controller and the second position controller checks whether the commanded steering angle, yaw rate, and lateral acceleration fall within a second specific range; and when the commanded steering angle, the yaw rate, and the lateral acceleration fall within the second specific range, each of the first position controller and the second position controller checks whether the position control error value is actually equal to or less than a second specific value.

[0017] The control method may further include: the corresponding position controller among the first position controller and the second position controller resets all the position control error values that have been accumulated so far, and the corresponding position controller maintains the state where the position control error value is equal to or less than the second specific value for a specified specific time.

[0018] The control method may further include: after resetting the accumulated position control error values, the corresponding position controller gradually increases the control gain in a ramp manner within a predetermined time.

[0019] The position control error value may be a position control error value filtered by considering errors outside the control frequency range caused by instantaneous disturbances or obstacles or potholes on the road.

[0020] According to an embodiment of the present invention, the electronic steering control device and the control method can remove the offset accumulated between two position controllers in a dual MDPS system, thereby stably performing autonomous driving control. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A diagram showing a schematic configuration of an electronic steering control device according to a first embodiment of the present disclosure.

[0022] Figure 2 A diagram showing a schematic configuration of an electronic steering control device according to a second embodiment of the present disclosure.

[0023] Figure 3 A flowchart for describing a control method of an electronic steering control device according to an embodiment of the present disclosure.

[0024] Figure 4 For showing in Figure 1 a diagram of the form of the control signal before and after removing the accumulated offset. DETAILED DESCRIPTION

[0025] As is customary in the corresponding field, some exemplary embodiments may be shown in the drawings in terms of functional blocks, units, and / or modules. Those of ordinary skill in the art will understand that these blocks, units, and / or modules are physically implemented by electronic (or optical) circuits such as logic circuits, discrete components, processors, hardwired circuits, memory elements, wiring connections, and the like. When the blocks, units, and / or modules are implemented by a processor or similar hardware, they can be programmed and controlled using software (e.g., code) to perform the various functions discussed herein. Alternatively, each block, unit, and / or module may be implemented by dedicated hardware or as a combination of dedicated hardware for performing some functions and a processor (e.g., one or more programmed processors and associated circuits) for performing other functions. Without departing from the scope of the inventive concept, each block, unit, and / or module of some exemplary embodiments may be physically separated into two or more interacting and discrete blocks, units, and / or modules. Additionally, without departing from the scope of the inventive concept, the blocks, units, and / or modules of some exemplary embodiments may be physically combined into more complex blocks, units, and / or modules.

[0026] Hereinafter, through various exemplary embodiments, an electronic steering control device and a control method thereof will be described with reference to the drawings.

[0027] It should be noted that the drawings are not drawn to an exact scale and the thickness of the lines or the dimensions of the components may be exaggerated solely for convenience and clarity of description. In addition, the terms used herein are defined by considering the functions of the present invention and may be changed according to the habits or intentions of the user or operator. Therefore, the definitions of the terms should be based on the overall disclosure described herein.

[0028] Figure 1 A diagram showing a schematic configuration of an electronic steering control device according to a first embodiment of the present invention. That is, Figure 1 A diagram showing an electronic steering control device (e.g., an MDPS system) to which a redundant system (i.e., a full redundant system) is applied.

[0029] As Figure 1 shown, the electronic steering control device according to the first embodiment of the present invention includes a control unit 110, a first position controller 121, a second position controller 122, a first motor 131, and a second motor 132.

[0030] Generally, an electronic steering control device (e.g., an MDPS system) to which a redundant system (i.e., a full redundant system) is applied refers to an electronic steering control device including two MDPS systems (or position controllers) 121 and 122.

[0031] Therefore, when any one of the MPDS systems (e.g., 121) fails, the other MDPS system (e.g., 122) can continuously perform steering control, so that autonomous driving or driver steering assistance can be continuously performed.

[0032] In an electronic steering control device (e.g., an MDPS system) to which a redundant system (i.e., a fully redundant system) is applied, the commanded steering angles θ1 and θ2 applied from the control unit 110 and the feedback steering angles θ respectively sensed by the two MDPS systems (or position controllers) 121 and 122 from the motors 131 and 132 m1 and θ m2 need to be ideally consistent with each other in order to perform position control. However, in practice, the commanded steering angles θ1 and θ2 and the feedback steering angles θ m1 and θ m2 are not consistent with each other, but an offset occurs between them (see Figure 4 ).

[0033] Therefore, in order to solve the problem of the occurrence of the offset, the control unit 110 receives the commanded steering angles θ1 and θ2 and the feedback steering angles θ m1 and θ m2 through internal communication between the two MDPS systems (or position controllers) 121 and 122, calculates the average values of the commanded steering angles θ1 and θ2 and the feedback steering angles θ m1 and θ m2 , and controls the position of the motor by using the same values (e.g., average values).

[0034] Therefore, even though the two MDPS systems (or position controllers) 121 and 122 have different commanded steering angles θ1 and θ2 and different feedback steering angles θ m1 and θ m2 , the control unit 110 can still calculate the average value in real time and perform position control by using the same value.

[0035] However, when there is a problem with the internal communication between the two MDPS systems (or position controllers) 121 and 122, the communication may be disconnected, or abnormal communication values may be obtained. The abnormal communication values may indicate that the commanded steering angle or the feedback steering angle is out of the error range.

[0036] Figure 2 A diagram showing a schematic configuration of an electronic steering control device according to a second embodiment of the present disclosure.

[0037] Figure 1 and Figure 2 The difference between the electronic steering control devices shown in Figure 1The two MDPS systems (or position controllers) 121 and 122 included in the electronic steering control device shown are connected through internal communication, while Figure 2 There is no internal communication between the two MDPS systems (or position controllers) 121 and 122 included in the electronic steering control device shown.

[0038] When the two MDPS systems (or position controllers) 121 and 122 cannot perform internal communication between them as described above, the MDPS systems 121 and 122 can perform control by means of a commanded steering angle and a feedback steering angle, respectively. In this case, offsets may accumulate, resulting in control output saturation.

[0039] Figure 3 FIG. is a flowchart for describing a control method of an electronic steering control device according to an embodiment of the present disclosure.

[0040] In step S101, when the two MDPS systems (or position controllers) 121 and 122 cannot perform internal communication between them as described above, if the position control error (i.e., the difference between the commanded steering angle and the feedback steering angle) falls within a specified specific range (first specific range), the MDPS systems (or position controllers) 121 and 122 respectively check whether the motor control current is equal to or greater than a specified specific value (first specific value).

[0041] When the motor control current is high, although there is no difference between the commanded steering angle and the feedback steering angle and thus no high control current is required, control output saturation is very likely to have occurred. Therefore, the MPDS systems 121 and 122 respectively check whether the motor control current is equal to or greater than the specified specific value.

[0042] In step S102, when control output saturation is detected or the motor control current is equal to or greater than the specified specific value (Yes in step S101), the corresponding MDPS system (position controller) 121 or 122 checks whether the commanded steering angle, yaw rate, and lateral acceleration fall within a specified specific range (second specific range).

[0043] This process is performed to determine whether the control current is not particularly required as in straight-ahead driving.

[0044] For example, when the commanded steering angle is around 0 degrees and the yaw rate and lateral acceleration are small values within a specified specific range (second specific range), the MDPS system 121 or 122 can determine that the vehicle is driving straight ahead. When the vehicle is driving straight ahead, a very low control current is required.

[0045] Therefore, in step S103, when it is determined that the control current is small or the commanded steering angle, yaw rate, and lateral acceleration fall within a specified specific range (second specific range), the MDPS system 121 or 122 checks whether the position control error value between the MDPS systems 121 and 122 is equal to or less than a specified specific value (second specific value).

[0046] That is, the MDPS system 121 or 122 checks again whether the position control error value is equal to or less than the specified specific value (second specific value) while normally performing position control.

[0047] At this time, although there is no actual difference between the commanded steering angle and the feedback steering angle, due to instantaneous disturbances or obstacles or potholes on the road, errors outside the control frequency range may occur. In this case, the MDPS system (or position controller) 121 or 122 eliminates the influence on offset calibration by filtering the position control error value.

[0048] In step S105, when the state where the position control error value is equal to or less than the specified specific value (second specific value) is maintained for a specified specific time (in step S104, yes), the MDPS system (or position controller) 121 or 122 can determine that autonomous driving control does not require a high control current, and based on this state, reset all the currently accumulated position control error values, or set the accumulated position control error value to 0.

[0049] When a large change in control input occurs immediately after the cumulative position error value is set to 0, because the linearity of the control or the cumulative position control error value of the position controller has been forcibly reset, the instantaneous change in the control output may cause vibration or oscillation without the control being optimized and stabilized.

[0050] Therefore, in step S106, in order to prevent the problem of vibration or oscillation that may be caused by the instantaneous change in the control output when the control is not optimized and stabilized, the MDPS system (or position controller) 121 or 122 gradually increases the control gain in a ramp-up manner during the next control cycle (i.e., the initial position control cycle) after resetting the cumulative position control error value.

[0051] For example, when assuming that the P gain and I gain of the control gain in a PID controller are 10 and 5 respectively, instead of immediately applying 10 and 5, the control gain gradually increases to 10 and 5 within a specified time. Therefore, although an instantaneous control change occurs, the final control output can change smoothly to reduce the sense of difference such as control oscillation or shock.

[0052] Figure 4 To show in Figure 1Morphological diagrams of the control signals before and after removing the cumulative offset.

[0053] Reference Figure 4 , due to various factors such as sensor characteristics or CAN communication delays, the commanded steering angle and the feedback steering angle are inconsistent with each other. Therefore, due to the continuous accumulation of the offset occurring during position control, the control output may saturate, making it impossible to normally execute position control, as Figure 4 in the case before removing the offset. Therefore, in this embodiment, the electronic steering control device can perform internal communication between two MDPS systems (or position controllers) 121 and 122 respectively in response to the situation where they can communicate internally with each other (see Figure 1 for the description) and the situation where the two MDPS systems (or position controllers) 121 and 122 do not have internal communication (see Figure 3 for the description) to remove the offset, as Figure 4 in the case after removing the offset. Then, the control output does not saturate while maintaining balance.

[0054] As described above, the electronic steering control device and the control method according to this embodiment can remove the offset accumulated between two position controllers in a dual MDPS system, thereby stably executing autonomous driving control.

[0055] Although the present disclosure has been described with reference to the embodiments shown in the drawings, these embodiments are provided for illustrative purposes only, and those skilled in the art can understand that various modifications and other equivalent embodiments can be made. Therefore, the technical scope of the present disclosure should be defined by the technical solutions of the present disclosure. In addition, for example, the embodiments described in this specification can be implemented by methods or processes, devices, software programs, data streams or signals. Although the features are discussed only in a single environment (for example, only discussed in a method), the discussed features can be implemented in another type (for example, a device or a program). The device can be implemented with appropriate hardware, software or firmware. The method can be implemented in a device such as a processor, which generally refers to a processing device, such as a computer, a microprocessor, an integrated circuit or a programmable logic device. The processor also includes communication devices, such as a computer, a cellular phone, a PDA (Personal Digital Assistant) and another device facilitating information communication between end users.

[0056] Although the exemplary embodiments of the present disclosure are disclosed for illustrative purposes, those skilled in the art can understand that various modifications, additions and substitutions can be made without departing from the scope and spirit of the present disclosure as defined in the technical solutions of the present disclosure. Therefore, the true technical scope of the present disclosure should be defined by the technical solutions of the present disclosure.

Claims

1. An electronic steering control device that applies a redundant system and includes a first position controller and a second position controller, Among them, When communication is established between the first position controller and the second position controller, The first position controller controls the position of the first motor based on the commanded steering angles θ1 and θ2 from the control unit and the feedback steering angles θ m1 and θ m2 from the motor, and The second position controller controls the position of the second motor according to the commanded steering angles θ1 and θ2 from the control unit and the feedback steering angles θ m1 and θ m2 from the motor. wherein, when the communication between the first position controller and the second position controller is cut off, Each of the first position controller and the second position controller is configured to: When the position control error value corresponding to the difference between the commanded steering angle and the feedback steering angle falls within a first specific range, check whether the motor control current is equal to or greater than a first specific value, When the motor control current is equal to or greater than the first specific value, check whether the commanded steering angle, yaw rate, and lateral acceleration fall within a second specific range, and When the commanded steering angle, the yaw rate, and the lateral acceleration fall within the second specific range, check whether the position control error value is actually equal to or less than a second specific value.

2. The electronic steering control device according to claim 1, wherein, When communication is established between the first position controller and the second position controller, The first position controller calculates the average values of the commanded steering angles θ1 and θ2 and the feedback steering angles θ m1 and θ m2 and controls the position of the first motor based on the calculated average values, and The second position controller calculates the average values of the commanded steering angles θ1 and θ2 and the feedback steering angles θ m1 and θ m2 and controls the position of the second motor according to the calculated average value.

3. The electronic steering control device according to claim 1, wherein, Between the first position controller and the second position controller, when the state where the position control error value is equal to or less than the second specific value is maintained for a specified specific time, the corresponding position controller resets all the position control error values that have been accumulated so far.

4. The electronic steering control device according to claim 3, wherein, After resetting the accumulated position control error values, the corresponding position controller gradually increases the control gain in a ramp-up manner within a predetermined time.

5. The electronic steering control device according to claim 3, wherein, The position control error value is a position control error value filtered by considering errors outside the control frequency range caused by instantaneous disturbances or obstacles or potholes on the road.

6. A control method for an electronic steering control device, the electronic steering control device applying a redundant system and including a first position controller and a second position controller, the control method includes: When communication is established between the first position controller and the second position controller: The first position controller controls the position of the first motor based on the commanded steering angles θ1 and θ2 from the control unit and the feedback steering angles θ m1 and θ m2 from the motor; and The second position controller controls the position of the second motor according to the commanded steering angles θ1 and θ2 from the control unit and the feedback steering angles θ m1 and θ m2 from the motor. The control method further includes, when the communication between the first position controller and the second position controller is cut off: When the position control error value corresponding to the difference between the commanded steering angle and the feedback steering angle falls within a first specific range, each of the first position controller and the second position controller checks whether the motor control current is equal to or greater than a first specific value, When the motor control current is equal to or greater than the first specific value, each of the first position controller and the second position controller checks whether the commanded steering angle, yaw rate, and lateral acceleration fall within a second specific range; And When the commanded steering angle, the yaw rate, and the lateral acceleration fall within the second specific range, each of the first position controller and the second position controller checks whether the position control error value is actually equal to or less than a second specific value.

7. The control method according to claim 6, wherein, When communication is established between the first position controller and the second position controller, The first position controller calculates the average values of the commanded steering angles θ1 and θ2 and the feedback steering angles θ m1 and θ m2 and controls the position of the first motor based on the calculated average values, and The second position controller calculates the average values of the commanded steering angles θ1 and θ2 and the feedback steering angles θ m1 and θ m2 and controls the position of the second motor based on the calculated average value.

8. The control method according to claim 6 further includes resetting, by a corresponding position controller of the first position controller and the second position controller, all the position control error values that have been accumulated so far, and the corresponding position controller maintaining a state where the position control error value is equal to or less than the second specific value for a specified specific time.

9. The control method according to claim 8 further includes: After resetting the accumulated position control error values, the corresponding position controller gradually increases the control gain in a ramp manner within a predetermined time.

10. The control method according to claim 8, wherein, The position control error value is a position control error value filtered by considering errors outside the control frequency range caused by instantaneous disturbances or obstacles or potholes on the road.

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