RWA system control device and method

Abstract

There is provided an apparatus for controlling a front wheel actuator (RWA) system, the apparatus including: a sensor module configured to detect data of at least one of a steering angle, rack position information, an angular velocity of a steering wheel, and a column torque; and a processor configured to implement PID control logic based on sensing data detected by the sensor module and RWA position information fed back from the RWA system. The present disclosure can control an RWA system to improve steering responsiveness and NVH performance required to improve an SBW steering system.

Description

Technical Field

[0001] Exemplary embodiments of the present disclosure relate to an apparatus and method for controlling a road wheel actuator (RWA) system, and more particularly to an apparatus and method for controlling a front wheel actuator RWA system to improve the responsiveness and noise vibration harshness (NVH) performance required for a steer-by-wire (SBW) steering system through RWA system control. Background Art

[0002] Generally, in a vehicle steering device (or steering system), a power steering system has been developed and applied to provide convenience of driving operation by assisting the driver's steering wheel maneuverability, wherein such a power steering system has been developed and applied as a hydraulic system using hydraulics, an electric hydraulic system using hydraulics and electric power of an engine, and an electric system using only electric power of the engine.

[0003] Recently, steer-by-wire (SBW) type steering systems (or steer-by-wire systems) have been developed and applied to steer a vehicle using a power source such as an engine, rather than removing a mechanical connection between a steering wheel and wheels (i.e., the drive wheels of the vehicle), such as a steering column, a universal joint, or a pinion shaft.

[0004] This steer-by-wire system is a steering system in which the mechanical connection between the steering wheel and the front wheel steering system (i.e., the rack to which the drive wheels are connected) is disconnected, wherein the steering system is configured to receive a rotation signal of the steering wheel from an electronic control unit (ECU) through a communication line (e.g., Direct CAN (DCAN)) and start a steering motor connected to the rack to steer the vehicle in response to the input rotation signal of the steering wheel.

[0005] In recent years, a parking assistance system (PA) has been applied to vehicles to transmit a position control signal (ie, a steering position control signal) to a steering system to control the position of the wheels (ie, the steering position), thereby achieving automatic parking.

[0006] In order for the parking assist system (PA) to operate normally, the steering system implements position feedback control to follow the steering angle control command, wherein the steering system usually implements reaction force control, but when receiving a position control start signal, the steering system switches to a position control mode and follows the position command. More specifically, the position control (i.e., steering position control) uses feedback control, which implements a control action by utilizing the difference between the steering position according to the steering position command and the current steering position.

[0007] Meanwhile, the steer-by-wire (SBW) system includes a steering feedback actuator (SFA) system associated with a steering wheel portion and a front wheel actuator (RWA) system associated with a wheel portion, which are mechanically separated.

[0008] The SFA may include a steering wheel, a steering shaft, a reaction force motor, a steering angle sensor, a steering torque sensor, etc. The driver's steering intention may be input to the SFA through the steering wheel. A control unit (e.g., ECU) may receive information (steering information) about the driver's steering intention from the SFA and output a corresponding control signal to the RWA. The steering information may include a steering angle, a steering torque, etc.

[0009] However, since the steering responsiveness required by the steering angle control logic of the conventional motor driven power steering (MDPS) is not as fast as that required by the SBW RWA, it is difficult for the conventional MDPS steering angle control logic to simultaneously meet both fast steering responsiveness and NVH performance. In other words, the way to increase the steering response in the conventional P-PI controller is to increase the position control P gain, which is difficult to apply to real vehicles because the NVH performance of the entire system is reduced (e.g., running noise and tongue noise during sharp turns).

[0010] Therefore, steering angle control logic is required to meet the steering response and NVH standards required by SBW RWA.

[0011] The background technology of the present disclosure is disclosed in Korean Unexamined Patent Publication No. 10-2018-0065045 (published on June 18, 2018, and entitled “Steering Control Method of Steer-by-Wire System”). Summary of the invention

[0012] Various embodiments relate to a front wheel actuator (RWA) system control apparatus and method, which can improve steering responsiveness and noise vibration harshness (NVH) performance required for a steer-by-wire (SBW) steering system by controlling the RWA system.

[0013] In one aspect of the present disclosure, a device for controlling a front wheel actuator (RWA) system is provided, the device comprising: a sensor module configured to detect data of at least one of a steering angle, rack position information, an angular velocity of a steering wheel, and a column torque; and a processor configured to implement a PID control logic based on the sensing data detected by the sensor module and the RWA position information fed back from the RWA system.

[0014] The PID control logic may include: a gain D (D cmd ) and a gain D(D) for the RWA position information fed back from the RWA system fed ).

[0015] The PID control logic may include a first adder configured to perform an addition operation on the target position command of the steering wheel and the RWA position information fed back from the RWA system to generate an error value corresponding to a difference therebetween.

[0016] The PID control logic may further include a P (proportional) controller configured to multiply the error value calculated by the first adder by a specified gain P.

[0017] The PID control logic may further include an I (integral) controller configured to integrate the error value calculated by the first adder and multiply the integrated error value by a specified gain I.

[0018] The PID control logic may further include a first D (derivative) controller configured to differentiate a value obtained by filtering the target position command using a first low-pass filter of a specified frequency (Hz) and multiply the derivative by a specified gain D (D cmd ).

[0019] The PID control logic may further include a second D (derivative) controller configured to differentiate a value obtained by filtering the RWA position fed back from the RWA system using a second low pass filter of a specified frequency (Hz), and multiply the derivative by a specified gain D (D fed ).

[0020] The PID control logic may further include a second adder configured to perform an addition operation on the values ​​output from the PID controller and output a resulting difference between the output values ​​to the RWA system.

[0021] In another aspect of the present disclosure, a method for controlling a front wheel actuator (RWA) system is provided, the method comprising: detecting, by a processor, sensing data from a sensor module; and implementing, by the processor, a PID control logic based on the sensing data and RWA position information fed back from the RWA system.

[0022] When implementing the PID control logic, the PID control logic may include: a gain D (D cmd ) and a gain D(D) for the RWA position information fed back from the RWA system fed ).

[0023] The present disclosure enables control of the RWA system to improve the steering responsiveness and NVH performance required of a SBW steering system. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is an exemplary diagram showing a schematic configuration of a steer-by-wire (SBW) system including a steering feedback actuator (SFA) system and a front wheel actuator (RWA) system according to an embodiment of the present disclosure.

[0025] Figure 2 is an exemplary diagram showing Figure 1 Schematic configuration of a control device of an RWA system.

[0026] Figure 3 is an exemplary diagram showing that Figure 2 The processor implements the steering angle control logic.

[0027] Figure 4A-4B and Figure 5 is a diagram showing the result of hardware in the loop simulation (HILS) steering responsiveness evaluation of a control device of an RWA system according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0028] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In the specification, the thickness of the lines or the size of the components shown in the drawings may be exaggerated for clarity and ease of explanation. In addition, the terms to be described below are terms defined in consideration of the functions in the present disclosure, which may vary according to the intention of the user or operator or the common practice in the art. Therefore, the definitions of these terms should be based on the entire content of this specification.

[0029] Embodiments of the present disclosure are described in detail below with reference to the accompanying drawings so that those skilled in the art can easily implement these embodiments. However, the present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. In order to clearly depict the present disclosure in the accompanying drawings, parts not related to the specification are omitted, and the same parts are represented by the same reference numerals throughout the specification.

[0030] Throughout the specification, whenever any part “includes” any components, it means including other components, rather than excluding other components, unless specifically stated otherwise.

[0031] The implementations described herein may be implemented, for example, as methods or processes, devices, software programs, data streams, or signals. Although discussed only in the context of a single implementation (e.g., only as a method), the implementation of the features discussed may also be implemented in other forms (e.g., as a device or program). Devices may be implemented using suitable hardware, software, firmware, etc. Methods may be implemented in a device (e.g., a processor), which generally refers to a processing device including a computer, a microprocessor, an integrated circuit, or a programmable logic device, etc.

[0032] As described above, the conventional engine driven power steering (MDPS) steering angle control logic has the form of a P-PI controller, and the steering angle command for the conventional MDPS steering angle control is received by the C-CAN, and since the command reception cycle is 10 to 20 ms or longer, the required responsiveness is 30 ms or longer, so that this requirement can be met with a P-PI controller tuning factor.

[0033] However, since the SBW system is the next-generation steering device that replaces the MDPS, it is necessary to ensure that the steering responsiveness and NVH performance are equal to or higher than those of the MDPS, but the P-PI controller tuning factor (P p , P pi , I pi : Position controller gain P, speed controller gain P, I) is difficult to meet the performance.

[0034] This is because, in a conventional P-PI controller, the way to increase responsiveness is to increase the position control gain P, but if this is done, the overall NVH performance of the system is reduced (for example, operating noise and tongue noise during sharp turns), which is difficult to apply to actual vehicles.

[0035] Therefore, the present disclosure provides a technique for implementing steering angle control to meet the responsiveness and NVH standards required for SBW RWA.

[0036] Figure 1 is an exemplary diagram showing a schematic configuration of a steer-by-wire (SBW) system including a steering feedback actuator (SFA) system and a front wheel actuator (RWA) system according to an embodiment of the present disclosure. Figure 2 is an exemplary diagram showing Figure 1 Schematic configuration of a control device of an RWA system. Figure 3 is an exemplary diagram showing that Figure 2 The processor implements the steering angle control logic.

[0037] Reference Figure 2 , the control device of the RWA system according to an embodiment of the present disclosure includes a sensor module 110 , a processor 120 , and a storage module 130 .

[0038] The sensor module 110 can detect sensing data such as a steering angle of a steering wheel, rack position information, an angular velocity of a steering wheel, and a column torque. Here, the rack position information may include a rack position, an angle of a rack position, and the like.

[0039] The sensor module 110 may include: a steering angle sensor for detecting rotational changes of a steering column according to a driver's steering wheel operation; a torque sensor installed on one side of a reaction force motor and a steering column for detecting a steering torque applied to the steering column or a reaction force torque output from the reaction force motor; an engine encoder sensor for detecting an angular velocity (rpm) of a steering wheel; a rack position sensor located on a rack rod for detecting rack position information; an engine torque sensor for detecting the torque of a driving engine, and the like.

[0040] The processor 120 may control the alignment of the steering wheel and rack positions based on the sensing data from the sensor module 110 .

[0041] The processor 120 may implement PID control to improve steering angle control response performance and NVH performance (see Figure 3 ).

[0042] Reference Figure 3 , compared to conventional P-PI controllers, embodiments may include multiple D gains to control system responsiveness.

[0043] For example, this embodiment may include: a gain D (D cmd ) and the gain D (D) for the RWA position information fed back from the RWA system 100 fed ) to improve system responsiveness.

[0044] The reason why the conventional PID formula is not used in this embodiment is that poor NVH performance and vibration may easily occur if the error derivative is directly used for the gain D as in the conventional PID formula. This is because the steering angle according to the command is received through CAN communication, so the resolution is necessarily low, and when the corresponding signal is differentiated, noise is generated, which degrades the NVH performance.

[0045] Therefore, since the derivative value of the target position command (i.e., the command angle) is very helpful in improving the response performance, the present embodiment uses the following PID formula to adjust and modify the target position command (i.e., the command angle) and the RWA position fed back from the RWA system 100 (i.e., the feedback angle) in the following manner: differentiating the value obtained by filtering the target position command and the RWA position using low-pass filters of different specified frequencies (Hz), and multiplying the derivative by a specified gain (D cmd , D fed )(See Figure 3 ).

[0046] The following PID formula is provided by reference to aid in understanding the PID control logic of the present disclosure.

[0047] θ cmd -θ fed =θ err

[0048]

[0049]

[0050] Θ: Angle (steering angle)

[0051] s :derivative

[0052] 1 / s: integral

[0053] PID basic :General PID control logic formula

[0054] PID RWA : Formula of PID control logic according to an embodiment of the present disclosure

[0055] ω: angular velocity

[0056] The storage module 130 is configured to store data related to the operation of the RWA system. In particular, the storage module 130 may store logic (or algorithm, application, program or applet, etc.) for implementing PID control to improve steering angle control responsiveness and NVH performance.

[0057] The storage module 130 may be collectively referred to as a non-volatile storage device that retains stored information even when power is not supplied, and a volatile storage device that requires power to retain stored information. The storage module 130 may also be used to temporarily or permanently store data processed by the processor 120. Here, in addition to a volatile storage device that requires power to maintain stored information, the storage module 130 may also include a magnetic storage medium or a flash storage medium, but the scope of the present disclosure is not limited thereto.

[0058] Hereinafter, the operation of the processor 120 will be described in detail.

[0059] like Figure 3 As shown, the PID control logic according to the present embodiment includes: a first adder 121 that performs an addition operation on a target position command of a steering wheel (not shown) and the RWA position information fed back from the RWA system 100 to generate an error value corresponding to the difference between them; a P (proportional) controller 122 that multiplies the error value calculated by the first adder 121 by a specified gain P; and an I (integral) controller 123 that integrates the error value calculated by the adder 121 and multiplies the integral by a specified gain I; a first D (differential) controller 125 that differentiates a value obtained by filtering the target position command (i.e., command angle) using a first low-pass filter 124 of a specified frequency (Hz) and multiplies the derivative by a specified gain D (D cmd ); a second D (derivative) controller 127 that differentiates a value obtained by filtering the RWA position (i.e., feedback angle) fed back from the RWA system 100 using a second low-pass filter 126 of a specified frequency (Hz), and multiplies the derivative by a specified gain D (D fed ); and a second adder 128, which performs an addition operation on the values ​​output by the PID controllers 122, 123, 125, and 127, and outputs the difference between the output values ​​to the RWA system 100.

[0060] As described above, the present embodiment may include a first D controller 125 and a second D controller 127, which include: a gain D (D cmd ) and the gain D (D) for the RWA position information fed back from the RWA system 100 fed ) to improve system responsiveness.

[0061] Figure 4A-4B and Figure 5is a graph showing the results of a hardware-in-the-loop simulation (HILS) steering responsiveness evaluation of a control device of an RWA system according to an embodiment of the present disclosure, which shows improved angle error and responsiveness compared to using a conventional P-PI control logic or a conventional PID control logic. In other words, referring to Figure 4A-4B , it can be seen that when the steering wheel is turned left and right (sine sweep 50 degrees until 4rps), the error degree ( Figure 4A Medium) and latency ( Figure 4B The delay time is also reduced.

[0062] In addition, if Figure 5 As shown, it can be seen that the delay time is also reduced when the steering wheel is turned sharply (step input 45 degrees / 900 degrees / second) to make a sharp turn or avoid an obstacle.

[0063] As described above, although a conventional P-PI controller or a conventional PID controller can increase responsiveness by using only the gain P, the present embodiment can increase responsiveness by using the gain D (D cmd ) to improve responsiveness, due to the gain D(D cmd ) improves transient response, so the NVH performance during sharp cornering can be improved, and the gain P can be reduced compared to a conventional PID controller, thereby providing an effect of improving the overall NVH performance because by using the gain D (D cmd ) Improved steering responsiveness.

[0064] Although the present disclosure has been described with reference to the embodiments shown in the accompanying drawings, these embodiments are merely exemplary and a person skilled in the art will appreciate that various modifications and other equivalent embodiments may be provided therefrom.

Claims

1. A device for controlling a front wheel actuator (RWA) system, the device comprising: a sensor module configured to detect data of at least one of a steering angle, rack position information, an angular velocity of a steering wheel, and a column torque; and A processor is configured to implement a PID control logic based on the sensing data detected by the sensor module and the RWA position information fed back from the RWA system.

2. The device according to claim 1, wherein: The PID control logic includes: a gain D (D cmd ) and a gain D(D) for the RWA position information fed back from the RWA system fed ).

3. The device according to claim 1, wherein: The PID control logic includes a first adder configured to perform an addition operation on the target position command of the steering wheel and the RWA position information fed back from the RWA system to generate an error value corresponding to a difference therebetween.

4. The device according to claim 3, wherein: The PID control logic further includes a P ratio controller configured to multiply the error value calculated by the first adder by a specified gain P.

5. The device according to claim 3, wherein: The PID control logic further includes an I integral controller configured to integrate the error value calculated by the first adder and multiply the integrated error value by a specified gain I.

6. The device according to claim 3, wherein: The PID control logic further includes a first D derivative controller configured to differentiate a value obtained by filtering the target position command using a first low-pass filter of a specified frequency (Hz) and multiply the derivative by a specified gain D (D cmd ).

7. The device according to claim 3, wherein: The PID control logic further includes a second D derivative controller configured to differentiate a value obtained by filtering the RWA position fed back from the RWA system using a second low pass filter of a specified frequency (Hz) and multiply the derivative by a specified gain D (D fed ).

8. The device according to claim 3, wherein: The PID control logic further includes a second adder configured to perform an addition operation on values ​​output from the PID controller and output a difference between the output values ​​to the RWA system.

9. A method for controlling a front wheel actuator (RWA) system, the method comprising: detecting, by a processor, sensing data from a sensor module; and A PID control logic is implemented by the processor based on the sensing data and RWA position information fed back from the RWA system.

10. The method according to claim 9, wherein: When the PID control logic is implemented, the PID control logic includes: a gain D (D cmd ) and a gain D(D) for the RWA position information fed back from the RWA system fed ).

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