Electronic steering device for a vehicle and control method thereof

Abstract

An electronic steering apparatus of a vehicle can include a reaction torque generation unit configured to generate an instruction reaction torque based on a steering condition of a driver, and a reaction torque control unit configured to receive a rack force and a vehicle speed, tune a road sensitivity according to the vehicle speed, set a road sensitive torque by applying a gain based on a reaction sensitivity, reflect the road sensitive torque in the instruction reaction torque, and output a final reaction torque to a driving motor. The electronic steering apparatus of the vehicle of the present invention can tune a road-dependent reaction sensitivity by applying a band pass filter to a rack force estimation value according to a vehicle speed, thereby providing a driver with a reaction feeling based on road characteristics.

Description

Technical Field

[0001] Exemplary embodiments of this disclosure relate to an electronic steering system for a vehicle and a control method thereof, and more specifically, to an electronic steering system for a vehicle and a control method thereof, wherein the electronic steering system applies a bandpass filter to a rack force estimate in an electronic steering system based on a Steer-By-Wire (SBW) system and provides the driver with a responsive feel based on road characteristics. Background Technology

[0002] Generally, power steering systems have been developed and used as steering devices in vehicles to improve driving convenience by assisting the driver in operating the steering wheel. These power steering systems are classified into hydraulic power steering systems that use hydraulic pressure; electro-hydraulic power steering systems that use both hydraulic pressure and the electromotive force of an electric motor; and electric steering systems that use only the electromotive force of an electric motor.

[0003] Recently, SBW systems have been developed and applied, which steer vehicles by controlling a motor connected to a rack based on electrical signals, eliminating the need for mechanical connectors (such as steering columns or universal joints) and pinion shafts between the steering wheel and the wheels.

[0004] This SBW system may include: a steering wheel for driver steering operations; a reaction motor mounted on one side of the steering wheel and configured to provide reaction torque based on the rotation of the steering wheel; a steering motor connected to a rack and configured to perform steering operations; multiple sensors configured to sense steering angle, vehicle speed, and steering wheel torque, respectively; and an electronic control unit (ECU) configured to drive the steering motor and the reaction motor based on electrical signals input from each sensor.

[0005] Because SBW (Side-by-Side Wheel) systems have no mechanical connections, they can reduce driver injury caused by mechanical parts in the event of a vehicle collision. Furthermore, the reduction in the number of mechanically connected parts reduces vehicle weight and unnecessary energy loss during steering maneuvers, and ideal steering performance can be achieved through ECU programming. Therefore, the use of SBW systems is gradually increasing.

[0006] The related technology disclosed herein is disclosed in Korean Patent Application No. 10-2018-0007393, entitled "Steering Control Device and Method in Steer-by-Wire System", published on January 23, 2018.

[0007] In this type of SBW-based electronic steering system, reaction control and steering control are performed by wires without mechanical connecting parts, and the vehicle's wheels are not physically connected to the steering wheel. Therefore, the electronic steering system generates reaction forces and provides steering feel to the driver based on steering angular velocity and vehicle speed. However, electronic steering systems struggle to control road reaction feel; undesirable steering feel caused by mechanical connections may be transferred to the driver's grip on the steering wheel, and steering feel caused by tire auto-alignment or backlash may not be transmitted to the driver's grip on the steering wheel. Therefore, electronic steering systems struggle to provide the driver with the required reaction force in real time.

[0008] Public content

[0009] Various embodiments relate to an electronic steering device for a vehicle and a control method thereof, the device tuning its road-responsiveness by applying a bandpass filter to an estimate of the rack force in the electronic steering device of a Steer-By-Wire (SBW) system and providing the driver with a road-characteristic-based responsiveness, wherein the bandpass of the bandpass filter is set according to the vehicle speed.

[0010] In one embodiment, an electronic steering system for a vehicle may include: a response torque generation unit configured to generate a command response torque based on the driver's steering conditions; and a response torque control unit configured to receive rack force and vehicle speed, tune road sensitivity according to vehicle speed, set road sensitivity torque by applying a gain based on response sensitivity, reflect the road sensitivity torque in the command response torque, and output the final response torque to a drive motor.

[0011] The responsive torque control unit may include: a sensitivity tuning unit configured to tune road sensitivity according to vehicle speed by passing through a rack force; and a gain setting unit configured to set a gain based on responsive sensitivity to the rack force filtered by the sensitivity tuning unit.

[0012] The sensitivity tuning unit may include: a bandpass filter unit configured to carry the bandpass filter rack force with a predetermined center frequency and bandwidth; a center frequency setting unit configured to set the center frequency of the bandpass filter unit according to the vehicle speed; and a bandwidth setting unit configured to set the bandwidth of the bandpass filter unit according to the vehicle speed.

[0013] The center frequency setting unit and bandwidth setting unit can be configured using corresponding tables to set the center frequency and bandwidth.

[0014] The gain setting unit may include a vehicle speed gain unit configured to set a gain based on vehicle speed.

[0015] The gain setting unit may also include one or more of the following: a steering angular velocity gain setting unit configured to set a decoupling gain based on steering angular velocity; and a column torque gain setting unit configured to set a decoupling gain based on column torque.

[0016] The vehicle speed gain setting unit, steering angle rate gain setting unit, and column torque gain setting unit can each have their gains set using corresponding tables.

[0017] In one embodiment, a control method for an electronic steering system of a vehicle may include: generating a command response torque by a response torque unit based on the driver's steering conditions; receiving rack force and vehicle speed by a response torque control unit, and tuning road sensitivity by filtering the rack force according to the vehicle speed; setting a road sensitivity torque by the response torque control unit by applying a gain based on the response sensitivity to the filtered rack force, and reflecting the set road sensitivity torque into the command response torque by the response torque control unit, and outputting the final response torque to a drive motor.

[0018] The tuning of road sensitivity may include: setting the center frequency for the filter to be driven by the responsive torque control unit according to the vehicle speed; setting the bandwidth for the filter to be driven by the vehicle speed; and driving the filter rack force according to the set center frequency and bandwidth according to the vehicle speed.

[0019] The center frequency and bandwidth can be set using the corresponding tables.

[0020] In setting the road-sensitive torque, the responsive torque control unit can set the road-sensitive torque by applying a gain based on vehicle speed to the filtered rack force, according to the responsiveness.

[0021] In setting the road sensitivity torque, the responsive torque control unit can also set the road sensitivity torque by further applying a decoupling gain to the filtered rack force based on the responsiveness, wherein the decoupling gain is based on one or more of the steering angular velocity and column torque.

[0022] According to embodiments of this disclosure, the electronic steering system of a vehicle can be an electronic steering system based on an SBW system, and the electronic steering system and control method can be tuned to road-dependent responsiveness by applying a bandpass filter (whose frequency band is set according to vehicle speed) to a rack force estimate based on vehicle speed, thereby providing the driver with a road-characteristic-based responsiveness. Attached Figure Description

[0023] Figure 1 This is a block diagram illustrating the configuration of an electronic steering device for a vehicle according to an embodiment of the present disclosure.

[0024] Figure 2 This is a configuration diagram showing the responsive torque control unit in the electronic steering system of a vehicle according to an embodiment of the present disclosure.

[0025] Figure 3 This is a fast Fourier transform (FFT) frequency analysis diagram of the speed-based rack force in the electronic steering system of a vehicle according to an embodiment of the present disclosure.

[0026] Figure 4 This is a torque analysis diagram showing the response of the electronic steering system of a vehicle according to an embodiment of the present disclosure before and after the application of road-sensitive torque.

[0027] Figure 5 This is a flowchart describing a control method for an electronic steering device in a vehicle according to embodiments of the present disclosure. Detailed Implementation

[0028] As is customary in the relevant field, some exemplary embodiments may be illustrated in the accompanying drawings as functional blocks, units, and / or modules. Those skilled in the art will understand that these blocks, units, and / or modules are physically implemented by electronic (or optical) circuitry such as logic circuits, discrete components, processors, hardwired circuitry, memory elements, wiring connections, etc. When blocks, units, and / or modules are implemented by processors or similar hardware, they can be programmed and controlled using software (e.g., code) to perform the various functions discussed herein. Optionally, each block, unit, and / or module may be implemented by dedicated hardware or as a combination of dedicated hardware performing some functions and processors (e.g., one or more programming processors and associated circuitry) 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 divided into two or more interactive and discrete blocks, units, and / or modules. Furthermore, without departing from the scope of the inventive concept, blocks, units, and / or modules of some exemplary embodiments may be physically combined into more complex blocks, units, and / or modules.

[0029] In the following description, the electronic steering system of a vehicle and its control method will be described with reference to the accompanying drawings through various exemplary embodiments. It should be noted that the drawings are not to precise scale and, for ease of description and clarity, the thickness of lines or the dimensions of components may be exaggerated. Furthermore, the terminology used herein is defined in consideration of the functionality of the invention and may be changed according to the habits or intentions of the user or operator. Therefore, the definition of terminology should be based on the overall disclosure set forth herein.

[0030] Figure 1 This is a block diagram illustrating the configuration of an electronic steering system in a vehicle according to an embodiment of the present disclosure. Figure 2This is a configuration diagram showing the responsive torque control unit in the electronic steering system of a vehicle according to an embodiment of the present disclosure. Figure 3 This is an FFT frequency analysis diagram of the speed-based rack force in the electronic steering system of a vehicle according to an embodiment of the present disclosure. Figure 4 This is a torque analysis diagram showing the response of the electronic steering system of a vehicle according to an embodiment of the present disclosure before and after the application of road-sensitive torque.

[0031] like Figure 1 and Figure 2 As shown, the electronic steering device of a vehicle according to an embodiment of the present disclosure may include a responsive torque generation unit 10 and a responsive torque control unit 20.

[0032] The electronic steering system of the vehicle according to an embodiment of this disclosure is an electronic steering system based on a Steer-By-Wire (SBW) system, which performs steering based on the steering angle and vehicle speed by driving a motor connected to a rack, and drives a drive motor 30 to generate a reaction force on the steering wheel. In this embodiment, when a steering mechanism is present, a detailed description of the steering control operation that controls the reaction torque by reflecting the column torque caused by the steering mechanism and performing steering via driving steering electrodes will be omitted herein.

[0033] The response torque generation unit 10 can generate command response torque based on the driver's steering conditions, such as vehicle speed, column torque, steering angular velocity, steering angle, rack force, etc.

[0034] The responsive torque control unit 20 can receive rack force and vehicle speed, tune road sensitivity according to vehicle speed, set road sensitivity torque by applying a gain based on responsive sensitivity, reflect the road sensitivity torque in the command responsive torque, and output the final torque to the drive motor 30.

[0035] like Figure 2 As shown, the response torque control unit 20 may include a sensitivity tuning unit 210 and a gain setting unit 220.

[0036] The sensitivity tuning unit 210 can carry a filter rack force to adjust the road sensitivity according to the vehicle speed.

[0037] The sensitivity tuning unit 210 may include a bandpass filter unit 216, a center frequency setting unit 212, and a bandwidth setting unit 214.

[0038] That is, the filter unit 216 uses a predetermined center frequency fc and bandwidth BW to drive the filter rack force.

[0039] The center frequency setting unit 212 can set the center frequency fc of the band filter unit 216 according to the vehicle speed. Simultaneously, the center frequency fc based on the vehicle speed can be configured as a table.

[0040] The bandwidth setting unit 214 can set the bandwidth of the band filter unit 216 according to the vehicle speed. At the same time, the bandwidth BW based on the vehicle speed can be configured as a table.

[0041] The center frequency and bandwidth can be set based on the road type by analyzing vehicle speed and rack force.

[0042] For example, Figure 3 This is an FFT frequency analysis diagram of the speed-based rack force in the electronic steering system of a vehicle according to an embodiment of the present disclosure.

[0043] Figure 3 This is an FFT frequency analysis plot of rack force based on speed on a Belgian road. This Belgian road is a test road, indicating an uneven road surface, such as a Belgian truck road.

[0044] like Figure 3 As shown, the frequency and amplitude of rack force peaks may vary depending on the low-speed range and the speed.

[0045] Therefore, road sensitivity can be tuned according to speed by setting the center frequency and bandwidth. Furthermore, road sensitivity can be reduced or increased based on response sensitivity.

[0046] The gain setting unit 220 can reduce or increase the road sensitive torque by setting a gain based on the responsiveness of the rack force filtered by the sensitivity tuning unit 210.

[0047] The gain setting unit 220 can set a gain based on vehicle speed, and can also set a decoupling gain based on steering angular velocity and column torque.

[0048] That is, the gain setting unit 220 may also include one or more of the steering angular velocity gain setting unit 224, the column torque gain setting unit 226, and the vehicle speed gain setting unit 222.

[0049] The vehicle speed gain setting unit 222 can reduce or increase road-sensitive torque by setting a gain based on vehicle speed.

[0050] For example, the vehicle speed gain setting unit 222 can reduce or increase road sensitivity torque in order to transmit road characteristics as much as possible at low speeds, but make the driver less sensitive to road characteristics at high speeds.

[0051] The steering angular velocity gain setting unit 224 can set a decoupling gain based on the steering angular velocity, so that the driver can perceive road characteristics during low-speed steering, but is not sensitive to road characteristics during high-speed steering.

[0052] The column torque gain setting unit 226 can set the decoupling gain based on the column torque.

[0053] The vehicle speed gain setting unit 222, the steering angular velocity gain setting unit 224, and the column torque gain setting unit 226 can each be set to their optimal values ​​through testing based on the corresponding tables.

[0054] Figure 4 This is a torque analysis diagram showing the response of the electronic steering system of a vehicle according to an embodiment of the present disclosure before and after the application of road-sensitive torque.

[0055] Figure 4 The results are shown by tuning the road sensitivity in the 10 to 15 Hz frequency range, actually measuring the road reaction force, and performing FFT analysis on the measured road reaction force. The results show that road vibration was attenuated.

[0056] As described above, the electronic steering device of the vehicle according to the embodiments of the present disclosure is an electronic steering device based on the SBW system, and can be tuned to road-dependent responsiveness by applying a bandpass filter to the rack force estimate according to the vehicle speed, thereby providing the driver with a road-characteristic-based responsiveness, wherein the bandpass of the bandpass filter is set according to the vehicle speed.

[0057] Figure 5 This is a flowchart describing a control method for an electronic steering device in a vehicle according to embodiments of the present disclosure.

[0058] like Figure 5 As shown, the control method of the electronic steering device of the vehicle according to this embodiment starts from step S10, wherein the response torque generation unit 10 generates a command response torque based on the driver's steering conditions (e.g., vehicle speed, column torque, steering angular velocity, steering angle, and rack force).

[0059] After the response torque generation unit 10 generates the command response torque in step 10, the response torque control unit 20 receives the rack force and vehicle speed in step 20, and tunes the road sensitivity by filtering the rack force according to the vehicle speed.

[0060] The responsive torque control unit 20 can tune road sensitivity by filtering rack force through a bandpass filter (which sets the center frequency fc and bandwidth BW according to vehicle speed).

[0061] Meanwhile, the center frequency fc and bandwidth BW can be set according to the road type by analyzing vehicle speed and rack force, and the center frequency and bandwidth based on vehicle speed can be configured as a table.

[0062] After tuning the road sensitivity by filtering the rack force in step S20, in step 30, the responsive torque control unit 20 reduces or increases the road sensitivity torque by setting a gain based on the responsive sensitivity to the filtered rack force.

[0063] The gain settings based on responsiveness can include setting a gain based on vehicle speed, and additionally setting a decoupling gain based on steering angular velocity and column torque.

[0064] For example, the responsive torque control unit 20 can reduce or increase road-sensitive torque to transmit as much road characteristics as possible at low speeds, but make the driver less sensitive to road characteristics at high speeds.

[0065] Furthermore, the responsive torque control unit 20 can be set with a decoupling gain based on steering angular velocity, so that the driver can perceive road characteristics during low-speed steering but is not sensitive to road characteristics during high-speed steering, and the responsive torque control unit 20 can be set with a decoupling gain based on column torque.

[0066] The optimized values ​​for the gain based on vehicle speed and the decoupling gain based on steering angular velocity and column torque can be set by testing according to the corresponding tables.

[0067] After setting the road sensitive torque in step S30, in step S40, the response torque control unit 20 reflects the set road sensitive torque in the command response torque and outputs the final response torque to the drive motor 30.

[0068] According to the control method of the electronic steering device of the vehicle according to the embodiments of the present disclosure, the electronic steering device is an electronic steering device based on the SBW system, and can be tuned to road-dependent responsiveness by applying a bandpass filter (the frequency band of which is set according to the vehicle speed) to the rack force estimate, thereby providing the driver with a responsive feel based on road characteristics.

[0069] The embodiments described in this specification can be implemented, for example, as methods or processes, apparatuses, software programs, data streams, or signals. While features are discussed only in a single context (e.g., only in the context of methods), the discussed features can be implemented in another type (e.g., apparatus or program). Apparatuses can be implemented in suitable hardware, software, or firmware. Methods can be implemented in devices such as processors, which generally refer to processing devices including computers, microprocessors, integrated circuits, or programmable logic devices. The processor also includes communication devices such as computers, mobile phones, personal digital assistants (PDAs), and other devices that facilitate information communication between end users.

[0070] Although exemplary embodiments of this disclosure have been disclosed for illustrative purposes, those skilled in the art will understand that various modifications, additions, and substitutions are possible without departing from the scope and spirit of this disclosure as defined by the technical solutions. Therefore, the true technical scope of this disclosure should be defined by the technical solutions.

Claims

1. An electronic steering system for a vehicle, comprising: The response torque generation unit is configured to generate command response torque based on the driver's steering conditions; as well as The responsive torque control unit is configured to receive rack force and vehicle speed, tune road sensitivity according to vehicle speed, set road sensitivity torque by applying a gain based on responsive sensitivity, reflect the road sensitivity torque in the commanded responsive torque, and output the final responsive torque to the drive motor. The reaction torque control unit includes: The sensitivity tuning unit is configured to have a passing rack force to tune road sensitivity according to vehicle speed; and The gain setting unit is configured to set a gain based on the response sensitivity to the rack force filtered by the sensitivity tuning unit.

2. The electronic steering device according to claim 1, wherein, The sensitivity tuning unit includes: The filter unit is configured to carry the filter rack force with a predetermined center frequency and bandwidth; The center frequency setting unit is configured to set the center frequency of the band filter unit according to the vehicle speed; and The bandwidth setting unit is configured to set the bandwidth of the band filter unit according to the vehicle speed.

3. The electronic steering device according to claim 2, wherein, The center frequency setting unit and the bandwidth setting unit set the center frequency and bandwidth through corresponding tables.

4. The electronic steering device according to claim 1, wherein, The gain setting unit includes a vehicle speed gain setting unit, which is configured to set a gain based on vehicle speed.

5. The electronic steering device according to claim 4, wherein, The gain setting unit further includes any one or more of the following: The steering angular velocity gain setting unit is configured to set a decoupling gain based on the steering angular velocity; and The column torque gain setting unit is configured to set the decoupling gain based on the column torque.

6. The electronic steering device according to claim 5, wherein, The vehicle speed gain setting unit, the steering angle rate gain setting unit, and the column torque gain setting unit each set their gains using corresponding tables.

7. A method for controlling an electronic steering system in a vehicle, comprising: The command response torque is generated by the response torque generation unit based on the driver's steering conditions; The responsive torque control unit receives rack force and vehicle speed, and tunes road sensitivity by filtering rack force based on vehicle speed; The road-sensitive torque is set by the responsive torque control unit by applying a gain based on responsiveness to the filtered rack force; as well as The reaction torque control unit reflects the set road sensitivity torque into the command reaction torque and outputs the final reaction torque to the drive motor.

8. The control method according to claim 7, wherein, The tuning path sensitivity includes: The responsive torque control unit sets the center frequency for the filter according to the vehicle speed; The bandwidth for the pass-through filter is set according to the vehicle speed; and Based on the vehicle speed, the force is applied to the filter rack using the set center frequency and set bandwidth.

9. The control method according to claim 8, wherein, The center frequency and bandwidth are set through the corresponding tables.

10. The control method according to claim 7, wherein, When setting the road-sensitive torque, the responsive torque control unit sets the road-sensitive torque by applying a gain based on vehicle speed to the filtered rack force, according to the responsiveness.

11. The control method according to claim 10, wherein, When setting the road sensitivity torque, the response torque control unit sets the road sensitivity torque by further applying a decoupling gain to the filtered rack force according to the response sensitivity, wherein the decoupling gain is based on one or more of the steering angular velocity and column torque.

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