Device and method for controlling a steer-by-wire steering system

Abstract

Device (100) for controlling a steer-by-wire steering system, the device comprising: a steering angle sensor configured to detect a steering angle position; a steering position control command receiver (120) configured to receive a steering position control command y2 from a designated external module; and a processor (110) configured to generate a steering angle position signal y1 based on the steering angle position from the steering angle sensor, to calculate a compensation gain x corresponding to a column torque or an electric motor current of a steering force actuator (SFA) when driver input occurs, to calculate a final steering position control command Y by reflecting the compensation gain x onto the steering angle position signal y1 and the steering position control command y2, and to output the final steering position control command Y to the steering force actuator (SFA), characterized in that the processor (110) calculates the final steering position control command Y by subtracting a value resulting from multiplying the steering position control command y2 by the compensation gain x from a valuewhich results from multiplying the steering angle position signal y1 by "1 - the compensation gain x".

Description

BACKGROUND

[0001] Exemplary embodiments of the present disclosure relate to a device and a method for controlling a steer-by-wire steering system, and in particular to a device and a method for controlling a steer-by-wire steering system, wherein the device and the method are suitable for detecting driver input during steering angle position control for automatic parking and for compensating the steering angle position control in a steer-by-wire (SBW) steering system in which a steering force actuator (SFA) and a road wheel actuator (RWA) are not mechanically connected. The device and the method can prevent the driver from perceiving a sensation of an impact and prevent a collision from occurring. BACKGROUND DISCUSSION

[0002] Power steering systems were typically designed and installed in vehicles as vehicle steering devices (or steering systems) to assist the driver in operating a steering wheel, thus providing the driver with the convenience of steering. These power steering systems include hydraulic-type systems that use hydraulic pressure, electro-hydraulic systems that use both hydraulic pressure and engine power, electro-type systems that operate solely with engine power, and so on.

[0003] In recent years, steer-by-wire (SBW)-type steering systems have been developed and installed in vehicles. With SBW-type steering systems, vehicle steering is performed using a motor, such as an electric motor, instead of removing a mechanical linkage device, such as a steering column, universal joint, or pinion shaft, between a steering wheel and a vehicle wheel (i.e., a vehicle drive wheel).

[0004] The SBW steering system is a steering system in which a steering wheel and a front-wheel steering device (i.e., a rack and pinion to which a drive wheel is connected) are mechanically separate. The SBW steering system receives a rotation signal from the steering wheel from an electronic control unit (ECU) via a communication line (e.g., direct CAN) and operates a steering motor connected to the rack and pinion based on the input rotation signal from the steering wheel, thereby steering a vehicle.

[0005] In recent years, parking assistance (PA) systems have been installed in vehicles. A parking assistance (PA) system transmits a position control signal (i.e., a steering position control signal) to a steering system, thereby controlling the position (i.e., the steering position) of a vehicle wheel and thus assisting with automatic parking.

[0006] In this case, to ensure the parking assist (PA) functions correctly, the steering system performs a feedback control that follows a steering angle control command. Under normal operating conditions, the steering system performs reaction force control. However, when a position control activation signal is received, the steering system switches to a position control mode and thus follows a position command.

[0007] More precisely, the position control (i.e., the steering position control) is a feedback control that uses a difference between a position according to a steering position control command and a current steering position.

[0008] However, in the prior art there was no method to determine driver involvement and to compensate for driver involvement while the parking assist (PA) system is performing steering control.

[0009] Therefore, if driver input occurs during steering control, the difference between the position corresponding to the steering position control command and the actual steering position increases, and a large force is generated to compensate for this difference. Due to the sensation of this input, the driver then over-steers. Consequently, there is a problem: there is a higher probability that this over-steering will lead to a vehicle accident.

[0010] In a steer-by-wire steering system, a mechanical linkage structure (i.e., a connection between a steering wheel and a front-wheel steering device) used in a steering system of related technology is eliminated. In this situation, there is a need for a technology to precisely control a front-wheel steering device (e.g., a front-wheel steering actuator) in a manner that corresponds to the steering position control command (i.e., the steering wheel rotation signal) resulting from the driver's steering wheel input.

[0011] An example of related prior art in relation to the present disclosure is disclosed in Korean patent application KR 10 2018 0 065 045 A (published on June 18, 2018, entitled “CONTROLLED METHOD FOR STEERING IN STEER-BY-WIRE SYSTEM”).

[0012] German patent application DE 10 2014 107 194 A1 discloses a method for operating an active steering system with a steering gear. During autonomous operation of the motor vehicle, driver intervention in the steering system is detected. The active steering system is operated in such a way that a coupling between an angle of the steering system and an angle input into the steering gear is established depending on the driver intervention thus detected.

[0013] From DE 10 2014 226 781 A1 a method and a device for determining a resulting setpoint for controlling a steering system of a vehicle is disclosed, wherein at least in an automated steering mode of a vehicle a setpoint for the automated steering mode is determined, wherein a setpoint for the manual steering mode is determined, and wherein the resulting setpoint is determined by changing the setpoint for the automated steering mode depending on the setpoint for the manual steering mode.

[0014] From DE 10 2014 220 865 A1, a device for controlling the lateral guidance of a vehicle is known. The device comprises a disturbance observer configured to generate a compensation signal to compensate for disturbances affecting the lateral guidance of the vehicle, wherein the compensation signal is independent of any manual torque applied to the vehicle's steering. The device further comprises a controller configured to determine a steering input for power steering of the vehicle as a controller output variable, based on one or more target trajectory values ​​for a target trajectory of the vehicle and based on the compensation signal. SUMMARY

[0015] Various embodiments relate to a device and a method for controlling a steer-by-wire steering system, wherein the device and the method are suitable for detecting driver input during steering angle position control for automatic parking and for compensating the steering angle position control in a steer-by-wire (SBW) steering system in which a steering force actuator (SFA) and a road wheel actuator (RWA) are not mechanically connected.

[0016] The problem is solved by a device for controlling a steer-by-wire steering system with the features of claim 1 and by a method for controlling a steer-by-wire steering system with the features of claim 7. Advantageous further developments are set out in the dependent claims.

[0017] A device for controlling a steer-by-wire steering system, the device comprising: a steering angle sensor configured to detect a steering angle position; a steering position control command receiver configured to receive a steering position control command y2 from a specific external module; a processor configured to generate a steering angle position signal y1 based on the steering angle position from the steering angle sensor, to calculate a compensation gain x corresponding to a column torque or an electric motor current of a steering force actuator (SFA) when driver input occurs, to calculate a final steering position control command Y by reflecting the compensation gain x onto the steering angle position signal y1 and the steering position control command y2, and to output the final steering position control command Y to the steering force actuator (SFA).

[0018] The device may include a parking assist (PA) system in the provided external module.

[0019] In the device, the compensation gain x can be a compensation gain x to compensate for a steering position control triggered by the driver's participation in steering during automatic steering by the provided external module.

[0020] In the device, the processor can calculate the compensation gain x, which corresponds to the column torque or the electric motor current, using a predefined equation or a lookup table.

[0021] In the device, the processor calculates the final steering position control instruction Y by subtracting a value resulting from a multiplication of the steering position control instruction y2 with "the compensation gain x" from a value resulting from a multiplication of the steering angle position signal y1 with "1 - the compensation gain x".

[0022] In the device, the final steering position control command Y can be transmitted via the steering force actuator (SFA) to a road wheel actuator (RWA).

[0023] In the device, if the driver's involvement is maintained continuously for a predetermined time or longer, the processor can terminate automatic steering position control by the provided external module and perform driver-initiated steering control.

[0024] A method for controlling a steer-by-wire steering system, comprising: generating a steering angle position signal y1 based on a steering angle position from a steering angle sensor by a processor; receiving a steering position control command y2 from a designated external module by a steering position control command receiver; calculating a compensation gain x corresponding to a column torque or an electric motor current of a steering force actuator (SFA) by the processor when there is driver involvement; and calculating a final steering position control command Y by the processor by reflecting the compensation gain x onto the steering angle position signal y1 and the steering position control command y2, and outputting the final steering position control command Y to the steering force actuator (SFA).

[0025] In this process, the intended external module can include a parking assistance (PA) system.

[0026] In this procedure, the compensation gain x can be a compensation gain x to compensate for a steering position control triggered by the driver's participation in steering during automatic steering by the intended external module.

[0027] In the method for calculating the compensation gain x, the processor can calculate the compensation gain x according to the column torque or the electric motor current using a predefined equation or a lookup table.

[0028] In this procedure, the processor calculates the final steering position control command Y by subtracting a value resulting from a multiplication of the steering position control command y2 with "the compensation gain x" from a value resulting from a multiplication of the steering angle position signal y1 with "1 - the compensation gain x".

[0029] In this method, the final steering position control command Y can be transmitted via the steering force actuator (SFA) to a road wheel actuator (RWA).

[0030] In this procedure, if the driver's involvement is maintained for a predetermined time or longer, the processor can terminate automatic steering position control by the provided external module and perform driver-initiated steering control.

[0031] According to one aspect of the present disclosure, the device and the method are suitable for detecting driver input during steering angle position control for automatic parking and for compensating for steering angle position control in a steer-by-wire (SBW) steering system in which a steering force actuator (SFA) and a road wheel actuator (RWA) are not mechanically connected. The device and the method can prevent the driver from feeling affected and can prevent a collision from occurring. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a diagram showing a schematic configuration of a device for controlling a steer-by-wire steering system according to a first embodiment of the present disclosure. Fig. Figure 2 is a flowchart showing a method for controlling a steer-by-wire steering system according to a second embodiment of the present disclosure. Fig. Figure 3 is a flowchart illustrating a procedure for controlling a steering position with a compensation gain x in Fig. 1 changes. DESCRIPTION OF THE EXECUTION FORMS SHOWN

[0032] As is common in the relevant field, some exemplary embodiments may be represented in the drawings in the form of functional blocks, units, and / or modules. Those skilled in the art will know that these blocks, units, and / or modules are physically implemented by electronic (or optical) circuits such as logic circuits, discrete components, processors, hard-wired circuits, memory elements, wiring connections, and the like. If the blocks, units, and / or modules are implemented by processors or similar hardware, they can be programmed and controlled by software (e.g., code) to perform various functions described 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., a microcontroller).(one or more programmed processors and associated circuits) to execute other functions. Each block, unit, and / or module of some exemplary embodiments can be physically divided into two or more interacting and discrete blocks, units, and / or modules without this deviating from the scope of the inventive concept. Furthermore, blocks, units, and / or modules of some exemplary embodiments can be physically combined to form more complex blocks, units, and / or modules without this deviating from the scope of the inventive concept.

[0033] A device and a method for controlling a steer-by-wire steering system, each according to a first and second embodiment of the present disclosure, are described below with reference to the accompanying drawings.

[0034] For the sake of clarity and simplicity, the line thicknesses and sizes of individual elements in the drawings may be exaggerated. Furthermore, a term defined by considering the function of a constituent element according to the present disclosure, to which the term is assigned, will be used below and may vary depending on the user's or manager's intent or technical conventions. Therefore, the term should be defined in the context of the present description.

[0035] Fig. Figure 1 is a diagram showing a schematic configuration of the device for controlling a steer-by-wire steering system according to the first embodiment of the present disclosure. Fig. Figure 3 is a flowchart illustrating a procedure for controlling a steering position with a compensation gain x in Fig. 1 changes.

[0036] As in Fig. Figure 1 shows a device 100 for controlling a steer-by-wire steering system according to the first embodiment, comprising a steering angle sensor (not shown), a steering position control command receiver (receiving unit) 120, and a processor 110. The processor 110 comprises a steering angle position signal calculation unit 111, a compensation gain calculation unit 112, and a steering position command calculation unit 113.

[0037] The steering angle position signal calculation unit 111 calculates a current steering angle position using a steering angle sensor (not shown) contained in a steering force actuator (SFA) and thus outputs a steering angle position signal y1.

[0038] The steering position control command receiver 120 receives a steering position control command y2 from a specific external module (e.g. a parking aid (PA) system).

[0039] The compensation gain calculation unit 112 calculates a compensation gain x, which corresponds to a column torque or electric motor current of the steering force actuator (SFA). The compensation gain x here is a compensation gain x for compensating the steering position control (i.e., the steering angle position control) by driver input (i.e., driver input in steering) during automatic steering by the designated external module (e.g., the parking assist (PA) system).

[0040] The compensation gain calculation unit 112 calculates the compensation gain x, which corresponds to the column torque or the electric motor current, using a predefined equation or lookup table.

[0041] The steering position command calculation unit 113 calculates a final steering position control command Y by reflecting the compensation gain x onto the steering angle position signal y1 and the steering position control command y2, and outputs the final steering position control command Y to the steering force actuator (SFA).

[0042] More precisely, the steering position command calculation unit 113 calculates the final steering position control command Y by subtracting a value (i.e. y2*x) resulting from multiplying the steering position control command y2 by "the compensation gain x" from a value (i.e. y1*(1-x)) resulting from multiplying the steering angle position signal y1 by "1 - the compensation gain x".

[0043] Therefore, if the compensation gain x is 1, the steering angle position signal y1 is multiplied by 0. Consequently, a state is reached in which no driver input occurs. Thus, the intended external module (e.g., the parking assist (PA)) performs only automatic steering position control on a 100% basis. In a case where the compensation gain x is 0, the steering angle position signal y2 is multiplied by 0. This disables automatic steering position control by the intended external module (e.g., the parking assist (PA) system), and only driver-initiated steering control is performed on a 100% basis (see Fig. 3) Furthermore, in a case where the compensation gain x 0 < x < 1, steering position control is performed to compensate for a steering position (see a tilt section in Fig. 3).

[0044] The final steering position control command Y, which is issued by the steering position command calculation unit 113, is transmitted via the steering force actuator (SFA) to a road wheel actuator (RWA) and is then used to control a steering position.

[0045] At this point, the processor 110 of the device 100 for controlling a steer-by-wire steering system according to the first embodiment stops the automatic steering position control by the provided external module (e.g. the parking aid (PA) system) in a case where the driver's involvement is maintained for a predetermined time or longer, and performs the driver-initiated steering control.

[0046] Fig. Figure 2 is a flowchart showing the method for controlling a steer-by-wire steering system according to the second embodiment of the present disclosure.

[0047] With reference to Fig. 2 In the method for controlling a steer-by-wire steering system according to the second embodiment, the steering angle position signal calculation unit 111 calculates the current steering angle position using the steering angle sensor (not shown) which is contained in the steering force actuator (SFA) and thus outputs the steering angle position signal y1 (S101).

[0048] In addition, the steering position control command receiver 120 receives the steering position control command y2 from the designated external module (e.g. the parking aid (PA) system) (S102).

[0049] In addition, the compensation gain calculation unit 112 calculates the compensation gain x, which corresponds to the column torque or the electric motor current of the steering force actuator (SFA) (S103).

[0050] The compensation gain x here is the compensation gain x for the compensation of the steering position control (i.e. the steering angle position control) by the participation of the driver (i.e. the driver's participation in steering) during automatic steering by the provided external module (e.g. the parking aid (PA) system).

[0051] That is, the compensation gain calculation unit 112 calculates the compensation gain x according to the column torque or the electric motor current using the given equation or reference table.

[0052] Additionally, the steering position command calculation unit 113 calculates the final steering position control command Y by reflecting the compensation gain x onto the steering angle position signal y1 and the steering position control command y2 and outputting the final steering position control command Y to the steering force actuator (SFA) (S104).

[0053] More precisely, the steering position command calculation unit 113 calculates the final steering position control command Y by subtracting a value (i.e. y2*x) resulting from multiplying the steering position control command y2 by "the compensation gain x" from a value (i.e. y1*(1-x)) resulting from multiplying the steering angle position signal y1 by "1 - the compensation gain x".

[0054] For example, if the compensation gain x is 1, the steering angle position signal y1 is multiplied by 0. This results in a state where there is no driver input, and therefore the intended external module (e.g., the parking assist (PA) system) performs automatic steering position control on a 100% basis. If the compensation gain x is 0, the steering angle position signal y2 is multiplied by 0. This disables automatic steering position control by the intended external module (e.g., the parking assist (PA) system), and driver-initiated steering control is performed on a 100% basis (see Fig. 3).

[0055] Furthermore, in the case where the compensation gain x 0 < x < 1, steering position control is performed to compensate for the steering position (see the inclination section in Fig.3) That is, in the case where the compensation gain x 0 < x < 1, it should be noted that instead of performing automatic steering position control or driver-initiated steering control, steering control is performed with a value for compensation.

[0056] The final steering position control command Y, which is issued by the steering position command calculation unit 113, is transmitted via the steering force actuator (SFA) to the road wheel actuator (RWA) and is then used to control the steering position.

[0057] At this point, the processor 110 for controlling a steer-by-wire steering system according to the first embodiment stops the automatic steering position control by the provided external module (e.g. the parking aid (PA) system) and performs the driver-initiated steering control (S105) in the case where the driver's involvement is maintained continuously for the specified time or longer.

[0058] As described above, in the second embodiment of the steer-by-wire (SBW) steering system, where the steering force actuator (SFA) is not mechanically connected, driver input during steering angle position control for automatic parking is detected, and the steering angle position control is then compensated. This achieves the beneficial effect of preventing the driver from perceiving any impairment and thus preventing vehicle accidents.

[0059] The embodiments of the present disclosure are described only by way of example with reference to the drawings. It will be obvious to a person with normal expertise in the field to which the present disclosure relates that various other modifications and equivalents from this description are possible. Therefore, the true technical scope of the disclosure should be defined by the following claims. The technical idea of ​​the present disclosure, as described in the present specification, can be realized, for example, in the form of a method, a process, an apparatus, a software program, a data stream, or a signal. The feature, even if described only in connection with its realization in a single form (e.g., only in the form of a method), can also be realized in another form (e.g., in the form of an apparatus or a program).The device can be implemented in the form of suitable hardware, software, firmware, or the like. The method can be implemented, for example, in a device such as a computer, a microprocessor, or a processor, which generally refers to a processing device such as an integrated circuit or a programmable logic device. Devices also include a computer that facilitates the communication of information between end users, a mobile phone, a portable / personal information terminal (a personal digital assistant ("PDA")), and other communication devices.

Claims

[1] Device (100) for controlling a steer-by-wire steering system, the device comprising: a steering angle sensor configured to detect a steering angle position; a steering position control command receiver (120) configured to receive a steering position control command y2 from a designated external module; and a processor (110) configured to generate a steering angle position signal y1 based on the steering angle position from the steering angle sensor, to calculate a compensation gain x corresponding to a column torque or electric motor current of a steering force actuator (SFA) when driver input occurs, to calculate a final steering position control command Y by reflecting the compensation gain x onto the steering angle position signal y1 and the steering position control command y2, and to output the final steering position control command Y to the steering force actuator (SFA), characterized by, that the processor (110) calculates the final steering position control instruction Y by subtracting a value resulting from a multiplication of the steering position control instruction y2 by "the compensation gain x" from a value resulting from a multiplication of the steering angle position signal y1 by "1 - the compensation gain x". [2] Device (100) according to claim 1, wherein the external module provided comprises a parking aid (PA) system. [3] Device (100) according to claim 1 or 2, wherein the compensation gain x is a compensation gain x for compensating a steering position control initiated by the driver's participation in steering during automatic steering by the provided external module. [4] Device (100) according to any one of claims 1 to 3, wherein the processor (110) calculates the compensation gain x according to the column torque or the electric motor current using a predetermined equation or lookup table. [5] Device (100) according to any one of claims 1 to 4, wherein the final steering position control command Y is transmitted via the steering force actuator (SFA) to a road wheel actuator (RWA). [6] Device (100) according to any one of claims 1 to 5, wherein in a case where the driver's involvement is maintained for a predetermined time or longer, the processor (110) stops automatic steering position control by the provided external module and performs driver-initiated steering control. [7] Method for controlling a steer-by-wire steering system, the method comprising: Generating a steering angle position signal y1 by a processor (110) based on a steering angle position from a steering angle sensor; Receiving a steering position control command y2 from a designated external module by a steering position control command receiver (120); Calculating a compensation gain x by the processor, corresponding to a column torque or an electric motor current of a steering force actuator (SFA), when driver input occurs; and The processor (110) calculates a final steering position control command Y by reflecting the compensation gain x onto the steering angle position signal y1 and the steering position control command y2, and outputs the final steering position control command Y to the steering force actuator (SFA). characterized by, that the processor (110), in order to compensate for the final steering position control instruction Y, calculates the final steering position control instruction Y by subtracting a value resulting from a multiplication of the steering position control instruction y2 by "the compensation gain x" from a value resulting from a multiplication of the steering angle position signal y1 by "1 - the compensation gain x". [8] Method according to claim 7, wherein the external module provided comprises a parking aid (PA) system. [9] Method according to claim 7 or 8, wherein the compensation gain x is a compensation gain x for the compensation of a steering position control triggered by the driver's participation in steering during automatic steering by the provided external module. [10] Method according to any one of claims 7 to 9, wherein the processor (110) calculates the compensation gain x according to the column torque or the electric motor current using a predetermined equation or lookup table. [11] Method according to any one of claims 7 to 10, wherein the final steering position control command Y is transmitted via the steering force actuator (SFA) to a road wheel actuator (RWA). [12] Method according to any one of claims 7 to 11, wherein in a case where the driver's involvement is maintained for a predetermined time or longer, the processor (110) stops the automatic steering position control by the provided external module and performs the driver-initiated steering control.

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