Steering control device

Abstract

The steering control device of the present application is applied to a steer-by-wire steering system (901) in which a steering manipulation mechanism and a steering mechanism are mechanically separated, or an electric power steering system (902) in which the steering manipulation mechanism and the steering mechanism are mechanically combined. The steering control device (201) applied to the steer-by-wire steering system (901) controls driving of a steering manipulation motor (78) that functions as a reaction force motor that imparts a reaction force torque to a steering wheel (91). When a condition prescribed in a stoppage of a vehicle is satisfied, a steering wheel lock operation section (75) of the steering control device (201) performs operation driving command to output a lock torque that maintains a rotation stop state of the steering wheel by energization of the steering manipulation motor (78) by "steering wheel lock driving control". A power converter (77) converts power supply power according to the driving command operated by the steering wheel lock operation section (75) and supplies the power to the steering manipulation motor.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to Japanese Patent Application No. 2020-156606, filed on September 17, 2020, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to steering control devices. Background Technology

[0004] Previously, devices were known to lock the rotation of the steering wheel while the vehicle was parked to prevent theft and to prevent accidental rotation when the steering wheel was touched. For example, in the steering wheel locking device disclosed in Patent Document 1, if the motor rotates in one direction, the locking lever moves in the locking direction and engages with the locking hole of the steering shaft to enter a locked state. Conversely, if the motor rotates in the other direction, the locking lever moves in the unlocking direction to enter an unlocked state.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2017-124794

[0006] Conventional steering wheel locking devices, such as those in Patent Document 1, use a mechanical structure that actuates a locking pin in conjunction with the ignition key. Furthermore, with the increasing adoption of smart keys and similar technologies in recent years, vehicles equipped with an engine start button utilize a steering wheel locking mechanism, an actuator to move the locking pin, and an electronic device to actuate the actuator. Using numerous such devices complicates the system structure, requires more space, and increases costs.

[0007] In particular, the space around the steering wheel is a major constraint. Because the area around and behind the steering wheel obstructs visibility, a large dashboard cannot be implemented, leading to strict limitations on its installation. Furthermore, the presence of collision safety structures and new human-machine interfaces such as head-up displays in this area further restricts space constraints. Additionally, in vehicles with steering-by-wire systems, there are situations where space is needed for a reaction force device that applies counter-torque to the back of the steering wheel. Therefore, to effectively ensure sufficient space around the steering wheel, it is necessary to eliminate mechanical steering wheel locking devices. Summary of the Invention

[0008] The purpose of this disclosure is to provide a steering control device that enables electric steering wheel locking.

[0009] The steering control device disclosed herein is applied to a steer-by-wire system in which the steering control mechanism and the steering mechanism are mechanically separated, or to an electric power steering system in which the steering control mechanism and the steering mechanism are mechanically combined.

[0010] The steering control device controls the drive of the steering motor, which functions as a reaction motor that imparts a reaction torque to the steering wheel in a wire steering system, or as a steering assist motor that imparts a steering assist torque to the steering wheel in an electric power steering system.

[0011] This steering control device includes a steering wheel lock calculation unit and a power converter. When specified conditions are met during parking, the steering wheel lock calculation unit executes a "steering wheel lock drive control" to maintain the steering wheel's rotation at a standstill by energizing the steering motor and outputting a locking torque. The power converter converts the power supply according to the drive command calculated by the steering wheel lock calculation unit and supplies it to the steering motor.

[0012] In this disclosure, the steering wheel lock calculation unit calculates drive commands to cause the steering control motor to output locking torque, thereby realizing the steering wheel lock function electrically. Therefore, there is no need for a steering wheel lock mechanism, actuator, electronic devices, or wiring, thus contributing to system simplification, ensuring sufficient space around the steering wheel, and reducing costs compared to mechanical steering wheel lock devices. Attached Figure Description

[0013] The above-mentioned objects, as well as other objects, features, and advantages of this disclosure, become more apparent from the accompanying drawings and the detailed description below. The accompanying drawings are:

[0014] Figure 1 This is an overall configuration diagram of the steer-by-wire system using the steering control device of this embodiment.

[0015] Figure 2A This is a control block diagram of the reaction force device in a steer-by-wire system.

[0016] Figure 2B This is a control block diagram of the steering mechanism in a steer-by-wire system.

[0017] Figure 3 This is an overall configuration diagram of the electric power steering system using the steering control device of this embodiment.

[0018] Figure 4 This is a block diagram showing the configuration of the steering wheel locking calculation unit in the first embodiment.

[0019] Figure 5 This is a block diagram showing the configuration of the steering wheel locking calculation unit in the second embodiment.

[0020] Figure 6 This is a block diagram showing the configuration of the steering wheel locking calculation unit in the third embodiment.

[0021] Figure 7This is a block diagram showing the configuration of the steering wheel locking calculation unit in the fourth embodiment.

[0022] Figure 8 It is a timing diagram showing the actions when a steering wheel torque exceeding the locking torque is input in the steering wheel lock drive control, and the actions when the steering wheel lock is released.

[0023] Figure 9 This is a spatial vector diagram illustrating the phase switching of the power supply in the steering wheel lock drive control.

[0024] Figure 10 This is a migration table explaining the phase switching in the steering wheel lock drive control.

[0025] Figure 11 This is a flowchart illustrating Example 1 of the steering wheel lock drive control activation / deactivation process.

[0026] Figure 12 This is a flowchart illustrating Example 2 of the steering wheel lock drive control activation / deactivation process.

[0027] Figure 13 This is a flowchart illustrating Example 3 of the steering wheel lock drive control activation / deactivation process. Detailed Implementation

[0028] Hereinafter, several embodiments of the steering control device of this disclosure will be described based on the accompanying drawings. The steering control device of this embodiment is applied to a vehicle's steer-by-wire system (hereinafter referred to as "SBW system") or electric power steering system (hereinafter referred to as "EPS system"), and is a device that electrically locks the rotation of the steering wheel when the vehicle is parked. The vehicle is not limited to a four-wheeled vehicle, but also includes motorcycles and handcarts. In this specification, the motor that functions as a reaction force motor in the SBW system and the motor that functions as a steering assist motor in the EPS system are collectively referred to as the "steering control motor". In summary, the steering control device of both systems controls the drive of the steering control motor.

[0029] [The composition of SBW and EPS systems]

[0030] First refer to Figures 1-3The configuration of the SBW system and the EPS system will be described below. In the following description, "normal operation" refers to periods other than when the driver is driving the vehicle and when starting or stopping, i.e., when the vehicle is parked and the steering wheel is locked. During normal operation, the reaction force control unit in the SBW system and the EPS control unit in the EPS system have different functions. However, in the parking state, which is the focus of this embodiment, the reaction force control unit and the EPS control unit have the same function. Therefore, for convenience, the same reference numeral "75" will be used for both the reaction force control unit and the EPS control unit in this specification, and they will be described together.

[0031] exist Figure 1 The overall configuration of the SBW system 901, in which the steering control mechanism and the steering mechanism are mechanically separated, is shown. Figure 1 The middle wheel 99 is shown only on one side; the wheel on the opposite side is omitted. The SBW system 901 includes a reaction force device 70 and a steering device 80.

[0032] The reaction force device 70 includes a reaction force device control unit 75, an inverter 77 which acts as a "power converter", and a reaction force motor 78 which acts as a "steering control motor". It is connected to the steering wheel 91 via a reaction force reducer 79 and a steering shaft 92. During normal operation, the reaction force device control unit 75 calculates the drive command of the reaction force motor 78 to impart a reaction torque to the steering wheel 91 for the driver's steering operation.

[0033] The inverter 77 converts the power supply according to the drive command calculated by the reaction force device control unit 75 and supplies it to the reaction force motor 78. In this embodiment, a three-phase brushless motor is used as the reaction force motor 78. The inverter 77 converts the DC power from the battery into three-phase AC power and supplies it to the reaction force motor 78. Furthermore, as an example, the reaction force device control unit 75, the inverter 77, and the reaction force motor 78 can be integrated into a so-called "electromechanical integrated motor".

[0034] The steering system 80 includes a steering system control unit 85 that calculates drive commands for the steering motor 88, an inverter 87, and the steering motor 88. The inverter 87 converts power according to the drive commands calculated by the steering system control unit 85 and supplies it to the steering motor 88. For example, the steering motor 88 may also be the same as the reaction motor 78, consisting of an electromechanical integrated three-phase brushless motor.

[0035] The rotation of the steering motor 88 is transmitted from the steering reducer 89 through the pinion 96, rack 97, steering tie rod 98, and steering knuckle arm 985 to the tire 99. In detail, the rotational motion of the pinion 96 is converted into the linear motion of the rack 97, and the steering tie rods 98 located at both ends of the rack 97 cause the steering knuckle arm 985 to reciprocate, thereby turning the tire 99.

[0036] The steering angle of the steering wheel 91 is determined by the direction of rotation of the steering wheel 91 relative to the neutral position, for example, by... Figure 1 The CW direction is defined as positive, and the CCW direction is defined as negative. Correspondingly, the positive and negative values ​​of the steering angle of the tire 99 are defined. The torque sensor 94 detects the steering torque Th input to the steering wheel 91 based on the torsional displacement of the torsion bar. The detected value Th of the torque sensor 94 is input to the reaction force device control unit 75.

[0037] The reaction force device control unit 75 and the steering device control unit 85 are primarily composed of microcomputers, and internally include components such as a CPU, ROM, RAM, I / O, and buses connecting these components (not shown). The processing in the reaction force device control unit 75 and the steering device control unit 85 can be either software processing based on the CPU executing pre-stored programs, or hardware processing based on dedicated electronic circuits. The reaction force device control unit 75 and the steering device control unit 85 communicate with each other via vehicle networks such as CAN communication or dedicated communication lines.

[0038] In the SBW system 901, the steering control device 201 comprises a reaction force control unit 75 including a reaction force device 70 and an inverter 77, and a steering device control unit 85 including a steering device 80 and an inverter 87. The steering control device 201 controls the reaction force motor 78 and the steering motor 88 to operate in a coordinated manner.

[0039] Reference Figure 2A , Figure 2B The general control configuration of the reaction force device 70 and the steering device 80 is described below. Parameters related to the output of the reaction force device 70 are prefixed with "r", and parameters related to the output of the steering device 80 are prefixed with "t". The rotation angle θr and angular velocity ωr of the reaction force motor 78 in the reaction force device 70, and the steering angle θt in the steering device 80, are converted values ​​multiplied by the transmission ratio of the reducers 79 and 89. In the figure, the reducers are omitted as "gears". Furthermore, the motor and gear are represented as a single module, labeled side-by-side with reference numerals "78, 79" or "88, 89".

[0040] exist Figure 2AThe control configuration of the reaction force device 70 is shown. The reaction force torque Tr can also be replaced by the reaction force motor current Ir, as shown in parentheses. Figure 2A The description states that the reaction torque Tr is used as the control variable.

[0041] The reaction force device control unit 75 includes a reaction force generation control unit 51, a reaction force generation control unit 52 for differential braking control, and a current control unit 680. The reaction force generation control unit 51 calculates the basic reaction force torque command value T*r_b based on the reaction force motor rotation angle θr, rotational angular velocity ωr, and reaction force motor current Ir. The reaction force generation control unit 52 for differential braking control calculates the differential braking reaction force torque command value T*r_d based on the difference between the reaction force motor rotation angle θr and the angle threshold θth, i.e., the differential braking. In adders 551 and 552, the basic reaction force torque command value T*r_b and the differential braking reaction force torque command value T*r are added to the steering torque Tt to calculate the reaction force torque command value T*r.

[0042] The current control unit 680 includes a deviation calculator 681 and a current controller 682, which generates drive commands for the reaction force motor 78 through feedback control of the reaction torque Tr. The inverter 77 supplies power to the reaction force motor 78 based on the output of the current controller 682. The reaction torque Tr output from the reaction force motor 78 via the reducer 79 is fed back to the deviation calculator 681.

[0043] exist Figure 2B The control configuration of the steering device 80 is shown. Steering torque can also be used instead of the steering motor current It. The steering device control unit 75 includes an angle control unit 360 and a current control unit 380. The angle deviation calculator 361 of the angle control unit 360 calculates the angle deviation Δθr-t between the rotation angle θr of the reaction force motor and the steering angle θt, which is communicated from the reaction force device 70. The angle controller 362 calculates the current command value I*t of the steering motor 88 to make the angle deviation Δθr-t approach 0.

[0044] The current control unit 380 includes a deviation calculator 381 and a current controller 382, ​​which generates drive commands for the steering motor 88 through feedback control of the steering motor current It. The inverter 87 supplies power to the steering motor 88 based on the output of the current controller 382. The steering angle θt output from the steering motor 88 via the reducer 89 is fed back to the angle deviation calculator 361.

[0045] The above describes the control configuration of the steering control device 201 during normal operation. During normal operation, the reaction force device control unit 75 calculates the reaction force torque based on steering information such as steering angle and steering torque, as well as steering information such as steering angle and rack travel, thereby allowing the driver to obtain an appropriate steering feel. On the other hand, as... Figure 1 As shown, the reaction force device control unit 75 also functions as a "steering wheel lock calculation unit 75" during parking. In other words, when the specified conditions are met during parking, the steering wheel lock calculation unit 75 calculates drive commands to output a locking torque that maintains the rotation of the steering wheel 91 at a stop by energizing the reaction force motor 78.

[0046] As information for determining whether the "prescribed conditions" are met, ignition switch (IG) signals, preparation signals, vehicle unlocking and locking signals, door opening and closing signals, and key operation signals are input to the steering wheel lock calculation unit 75 via the vehicle network. The meaning of the information indicated by these signals will be described later.

[0047] exist Figure 3 The overall structure of the EPS system 902, which integrates the steering control mechanism with the steering mechanism, is shown. Furthermore, although in Figure 3 The diagram shows a rack-assisted type EPS system, but the same applies to column-assisted type EPS systems. In EPS system 902, the steering shaft 92 and rack 97 are connected via an intermediate shaft 95. The rotation of the steering shaft 92 caused by the driver's steering input is mechanically transmitted to the rack 97 via the intermediate shaft 95 and pinion 96.

[0048] The EPS system 902 includes a steering assist motor 78 as a "steering motor". The steering control device 202 of the EPS system 902 consists of an EPS control unit 75 and an inverter 77. During normal operation, the EPS control unit 75 calculates the drive command of the steering assist motor 78 to provide steering assist torque to the steering wheel 91.

[0049] The EPS control unit 75 functions as a "steering wheel lock calculation unit 75" when the vehicle is parked. When the conditions specified in the parking position are met, the steering wheel lock calculation unit 75 of the EPS system 902 calculates drive commands to output a locking torque that maintains the rotation of the steering wheel 91 at a standstill by energizing the steering assist motor 78. In other words, the EPS control unit 75, which normally functions to steer the vehicle according to the driver's steering input, also has the additional function of steering wheel lock when the vehicle is parked.

[0050] As described above, in the steering control devices 201 and 202 applied to the SBW system 901 or EPS system 902, when the conditions specified in the parking state are met, the steering wheel lock calculation unit 75 calculates drive commands to maintain the rotation of the steering wheel 91 in a stopped state by energizing the steering control motor 78. This motor control based on the steering wheel lock calculation unit 75 is referred to as "steering wheel lock drive control". In this embodiment, the steering wheel lock drive control is implemented by the steering wheel lock calculation unit 75, so a mechanical steering wheel lock device is not required.

[0051] [Structure of the Steering Wheel Locking Calculation Unit]

[0052] Next, refer to Figures 4-7 The first to fourth embodiments related to the specific configuration of the steering wheel locking calculation unit 75 will be described. In each embodiment, the reference numeral for the steering wheel locking calculation unit is followed by the embodiment number in the third position after "75". Figures 4-7 In the middle, to and Figure 2A The same components are attached with the same reference numerals and the description is omitted. Furthermore, the symbol "r" for the reaction force device control unit is also shared in the EPS control unit.

[0053] like Figure 2A As referenced, the drive commands output to the inverter 77 in each diagram are equivalent to the operation quantities (e.g., voltage commands) that use torque or current as control quantities for feedback control. Figures 4-7 The purpose is to illustrate the configuration mode of the steering wheel lock drive control, omitting the description of the specific operating quantities output to the inverter 77. The operating quantities of control torque and current can be appropriately selected according to the control configuration such as PWM control, and modules such as conversion units can be added as needed.

[0054] (First Implementation)

[0055] Figure 4 The steering wheel locking calculation unit 751 of the first embodiment calculates drive commands to make the rotation angle θr of the steering motor 78 follow the rotation angle command value θ*r, thereby controlling the rotation angle θr of the steering motor 78 to remain a constant value. Hereinafter, the rotation angle θr of the steering motor 78 will be referred to simply as "rotation angle θr". The rotation angle command value θ*r can be 0, which corresponds to the neutral position, or a positive or negative value other than 0. As described above, the rotation angle θr is recorded as a converted value multiplied by the transmission ratio of the reducer 79.

[0056] The steering wheel lock calculation unit 751 includes an angle control unit 560 and a current control unit 680. The angle control unit 560's angle deviation calculator 561 calculates the angle deviation Δθr between the rotation angle command value θ*r and the rotation angle θr fed back from the steering motor 78 via the reducer 79. The angle controller 562 calculates the torque command value T*r or the current command value I*r to bring the angle deviation Δθr close to 0. The current control unit 680 calculates the drive command through feedback control of the torque Tr or the current Ir.

[0057] (Second Implementation)

[0058] Figure 5 The steering wheel lock calculation unit 752 of the second embodiment shown calculates the drive command so that the steering motor 78 outputs a reverse torque that counteracts the input steering wheel torque Th. Therefore, ideally, the initial rotation angle at the start of the steering wheel lock drive control is maintained.

[0059] The steering wheel lock calculation unit 752 includes a reverse torque calculation unit 66 and a current control unit 680. The reverse torque calculation unit 66 calculates the torque command value T*r or the current command value I*r to counteract the steering wheel torque Th. The current control unit 680 calculates the drive command through feedback control of the torque Tr or the current Ir.

[0060] (Third Implementation)

[0061] Figure 6 The steering wheel locking calculation unit 753 of the third embodiment shown controls the drive of the three-phase motor through vector control, and calculates the drive command for the electrical angle β of the dq-axis current vector Idq that energizes the steering motor 78. In other words, the steering wheel locking calculation unit 753 energizes the steering motor 78 in a manner that restricts the rotor position within a specified range.

[0062] The steering wheel lock calculation unit 753 inputs a dq-axis current command value Idq*, where the q-axis current is non-zero and the d-axis current is zero. The dq-axis current deviation calculator 671 calculates the deviation ΔIdq between the dq-axis current command value Idq* and the dq-axis current Idq fed back from the three-phase / dq conversion unit 674. The current controller 672 calculates the dq-axis voltage command Vdq to bring the dq-axis current deviation ΔIdq close to zero.

[0063] The dq / three-phase conversion unit 673 performs coordinate transformation on the dq-axis voltage command Vdq to calculate the three-phase voltage command Vuvw, and outputs it to the inverter 77. The three-phase / dq conversion unit 674 performs coordinate transformation on the three-phase current Iuvw flowing through the inverter 77, calculates the dq-axis current Idq, and feeds it back to the dq-axis current deviation calculator 671. Here, a fixed electrical angle is used in the calculations of the dq / three-phase conversion unit 673 and the three-phase / dq conversion unit 674, so the rotor position can be maintained.

[0064] Depending on the number of pole pairs in the brushless motor constituting the steering control motor 78, one cycle of rotation angle contains a cycle of electrical angles, thus the same electrical angle β appears multiple times within the movable range of the steering wheel 91. Therefore, in the third embodiment, after the steering wheel lock begins, the rotor position is effectively maintained within a relatively small angle range, provided that the steering wheel 91 does not rotate significantly.

[0065] (Fourth Implementation)

[0066] Figure 7 The steering wheel locking calculation unit 754 of the fourth embodiment shown is equivalent to a special method of the first embodiment that maintains the motor rotation angle at a constant value. In particular, the rotation angle θr of the steering motor 78 corresponding to the limit, i.e. the end, of the steering angle is used as the rotation angle command value θ*r, and the drive command is calculated.

[0067] Motorcycles and handcarts can be parked by turning the steering wheel 91 to either the left or right, i.e., at the end of either the positive or negative position relative to the neutral position. For example, if it is predetermined which end of the steering wheel will be locked, and control is always started when the driver turns the steering wheel 91 to near the end of the locked side, then according to the first embodiment, the steering control motor 78 can also be rotated slightly.

[0068] In contrast, since the driver is unsure which side to turn the steering wheel 91 to each time the vehicle is parked, it is impractical to rotate the steering wheel 91 from its current position to the opposite end. Therefore, the fourth embodiment controls the steering wheel to lock when the steering wheel is rotated to the closer end, based on the current rotation angle θr.

[0069] The steering wheel lock calculation unit 754 includes an angle control unit 570 and a current control unit 680, which have negative end angle θend_N and positive end angle θend_P as rotation angle command values. The discrimination unit 579 of the angle control unit 570 distinguishes the sign of the rotation angle θr fed back from the steering motor 78. Here, "θend_N≤θr≤θend_P".

[0070] The negative angle deviation calculator 571N calculates the negative angle deviation Δθr after subtracting the negative rotation angle θr from the negative end angle θend_N. The positive angle deviation calculator 571P calculates the positive angle deviation Δθr after subtracting the positive rotation angle θr from the positive end angle θend_P. The angle controllers 572N and 572P calculate the torque command value T*r or the current command value I*r to make each angle deviation Δθr close to 0.

[0071] Similar to the first embodiment, the current control unit 680 calculates drive commands through feedback control of torque Tr or current Ir. This executes steering wheel lock drive control to push the steering wheel to the end of the wheel on the same side as the current position.

[0072] [Application Control]

[0073] As described above, in this embodiment, the electric steering wheel locking mechanism is implemented by energizing the steering motor 78 for a purpose different from its normal operation. Therefore, a mechanical steering wheel locking device is unnecessary, and the space around the steering wheel can be effectively secured. In the future, with the addition of new human-machine interfaces, its effectiveness can be expected to be even greater. However, compared to a mechanical mechanism that maintains the locked state once locked until it is released, this embodiment presents new challenges unique to electric mechanisms. Therefore, the following will refer to… Figures 8-10 The application control of the steering wheel lock drive control is explained.

[0074] Assume the possibility of a "yielding phenomenon" in the steering wheel lock drive control, where the input steering torque Th is greater than the locking torque output by the steering motor 78. Figure 8 The timing diagram illustrates the action when a steering wheel torque Th exceeding the locking torque is input in the steering wheel lock drive control during the period from time t1 to t4. In the initial phase before time t1, the steering wheel angle (i.e., the motor rotation angle multiplied by the gear ratio) remains at its initial angle. In the first and fourth embodiments using the rotation angle command value, the initial angle corresponds to the initial value θ*r_0 of the rotation angle command value.

[0075] After time t1, the input of steering wheel torque Th begins. During the period up to time t2, the input steering wheel torque Th is below the locking torque output by the steering control motor 78, so the steering wheel angle remains unchanged. However, after time t2, the input steering wheel torque Th exceeds the locking torque output by the steering control motor 78, and the steering wheel 91 begins to rotate. Subsequently, at time t3, the input steering wheel torque Th falls below the locking torque, and the rotation of the steering wheel 91 stops. Let the steering wheel angle at time t3 be θr_#.

[0076] Subsequently, when continuing steering wheel lock drive control, the steering wheel lock calculation unit 75 can, for example, execute the following two controls. In the control shown in (*a), the steering wheel lock calculation unit 75 continues the steering wheel lock drive control in a manner that maintains the rotated steering wheel angle θr_#. This control can be applied to all of the first to fourth embodiments.

[0077] In the control shown in (*b), the steering wheel lock calculation unit 75 returns to the initial steering wheel angle θ*r_0 based on the rotation angle command value during times t3 to t4 and continues the steering wheel lock drive control. This control can be applied to the first and fourth embodiments using the rotation angle command value, and can prevent the steering wheel angle from deviating significantly from the initial angle even when the steering wheel torque Th exceeding the locking torque is repeatedly input in the same direction.

[0078] Next, in Figure 8 The timing diagram shows the action of steering wheel lock release during the period from t5 to t6. At t5, when steering wheel lock drive control is in progress, the steering wheel lock calculation unit 75 receives a release trigger from the vehicle and ends the steering wheel lock drive control. At this time, the steering wheel lock calculation unit 75 reduces the locking torque output by the steering motor 78 from t5 to t6. For example, if the locking torque is momentarily zero when the driver places their hand on the steering wheel 91, there is a concern that the steering wheel 91 might involuntarily rotate. Therefore, by reducing the locking torque, the driver can recognize the release of the lock.

[0079] Next, the prevention of continuous heat generation accompanying the steering wheel lock drive control will be explained. According to the first embodiment, when the rotation angle θr reaches the commanded value θ*r and the tire 99 is stationary due to friction with the road surface, the inverter 77 and the steering motor 78 are not further energized. Furthermore, in the second embodiment, the inverter 77 and the steering motor 78 are not energized unless the steering wheel torque Th is input, so the possibility of heat generation is considered low.

[0080] However, for example, when a driver falls asleep in a parked position with their weight on the steering wheel 91, there is a possibility that the steering wheel torque Th will be continuously input, and the power supply based on the steering wheel lock drive control will remain on for an extended period. Furthermore, in order to maintain continuous power supply to a specific phase of the three-phase motor at the rotation angle θr, there is a concern that heat will concentrate on the switching elements of that specific phase of the inverter 77. Therefore, it is preferable that the steering wheel lock calculation unit 75 changes the energized phase according to the energizing time during the implementation of steering wheel lock drive control to avoid power concentration on a specific phase of the steering motor 78.

[0081] For example in Figure 9In the method shown, the three-phase voltage is represented as a space vector. To obtain the current vector Ir that achieves the locking angle, heat dissipation can be achieved by sequentially switching between three modes: the synthesis of U-V phase vectors, the synthesis of U-W phase vectors, and the synthesis of V-W phase vectors.

[0082] Alternatively, one could consider gradually shifting the locking angle according to the energizing time, causing the steering motor 78 to oscillate. Figure 10 This diagram shows a migration table where two of the three phases are energized sequentially while the phase is being changed. For example, by alternating between six modes of energization in both forward and reverse directions, a locked angle can be maintained within a specified angle range.

[0083] [Start / Remove Processing]

[0084] Next, refer to Figures 11-13 The flowchart illustrates an example of the activation / deactivation process for the steering wheel lock drive control. In the flowchart description, the symbol "S" indicates a step. Furthermore, identical steps are assigned the same step number in each flowchart, and their descriptions are omitted. Hereinafter, anyone riding in the vehicle other than the licensed driver is designated as a "suspect" who may attempt to steal the vehicle.

[0085] exist Figure 11 Example 1 illustrates a flowchart used in both the SBW system 901 and the EPS system 902, assuming a process from the driver parking the vehicle to the start of driving. In S11, the steering wheel lock calculation unit 75 determines whether the engine is stopped or the preparation signal is off, and the ignition switch signal is off. If the condition is met in S11, the steering wheel lock calculation unit 75 initiates steering wheel lock drive control in S12. Furthermore, it is assumed that the driver gets out of the vehicle in S13, and then gets back in in S14 after a certain period of time.

[0086] For example, if a person is identified as having entered the vehicle based on a vehicle unlocking or driver's side door opening signal, formal driver authentication is performed in S15. Only if the driver is identified as having entered the vehicle will the process proceed to S16. In S16, the steering wheel lock calculation unit 75 determines whether a steering wheel torque Th exceeding the release threshold has been input into the steering wheel lock drive control, or whether a "driving start release trigger" has been received from the vehicle, such as an IG on signal or a key operation signal. If the driver is identified as having entered the vehicle in S16, the steering wheel lock calculation unit 75 stops the steering wheel lock drive control and releases the lock in S18. This allows the driver to perform driving actions including steering. Furthermore, the driver is not considered capable of driving only when they can drive straight.

[0087] However, assuming that the lock was released in S18 based on other conditions before IG was engaged, and then the driver applies steering wheel torque Th. In the EPS system 902, even if the assist was not started before IG was engaged, rotational resistance is generated because the steering wheel 91 is mechanically engaged with the steering mechanism.

[0088] On the other hand, in the SBW system 901, if the lock is released before the reaction motor 78 is in a state where it can output the reaction torque for normal operation, the steering wheel 91, which is mechanically separated from the steering mechanism, will spin freely without resistance when the steering wheel torque Th is applied. For example, there is a concern that a driver who mistakenly believes that the steering wheel 91 is fixed may apply their weight to the steering wheel 91, causing the steering wheel 91 to spin freely and break the balance. Therefore, in the SBW system 901, it is preferable that the steering wheel lock calculation unit 75 continues the steering wheel lock drive control after the driver enters the vehicle until the reaction motor 78 is in a state where it can output the reaction torque.

[0089] Therefore, although it is recorded above as " Figure 11 It is used in both SBW system 901 and EPS system 902, but is generally more suitable for EPS system 902. Reflecting this, in Figure 12 A flowchart is shown to prevent steering wheel idling when the driver is in the vehicle, assuming the SBW system 901, as “Processing Example 2”.

[0090] Figure 12 S11~S14 and Figure 11 Same. However, in Figure 12 Instead of using the release step in S16, S17 determines whether the reaction force motor 78 is capable of outputting reaction force torque. If it is in S17, the steering wheel lock calculation unit 75 stops the steering wheel lock drive control and releases the lock in S18. Furthermore, when using the IG energizing signal and the key operation signal as conditions for starting the normal operation of the reaction force device 70, it is also possible to include their trigger reception determination in the determination in S17.

[0091] With the steering mechanism of the SBW system 901 disconnected from the steering mechanism, even if the steering wheel lock is released, as long as the reaction force device 70 does not begin its normal operation, a suspect cannot use the steering wheel 91 to steal the vehicle. In other words, the steering wheel lock is not intended solely to prevent theft. Rather, it is intended to assist the driver's actions while in the vehicle. Figure 12 The processing can improve the safety and convenience of the SBW system 901 when the driver is in the vehicle.

[0092] If the steering wheel lock drive control is continuously powered, there is a concern about battery depletion during prolonged parking. To prevent this, a solution is considered for switching to a "sleep mode" that disables steering wheel lock drive control when the vehicle is parked and unoccupied. Furthermore, a solution is considered for deactivating the sleep mode if torque input or steering wheel angle changes are detected during sleep mode. Therefore, in Figure 13 The flowchart shown in both SBW system 901 and EPS system 902 assumes a transition from sleep mode to steering wheel relock, as “Processing Example 3”.

[0093] S21 is the next... Figure 11 , 12 In S12, "steering wheel locked" refers to the state after the steering wheel lock drive control has started. In S22, the steering wheel lock calculation unit 75 determines whether a "sleep mode release trigger" has been triggered, such as receiving a vehicle lock signal from the vehicle, or whether a state where no steering wheel torque Th is input has elapsed for a predetermined time. If the condition is yes in S22, in S23, the steering wheel lock calculation unit 75 stops the steering wheel lock drive control and moves to sleep mode. In sleep mode, the steering control devices 201 and 202 are completely stopped, and the power supply to the steering motor 78 is stopped. Therefore, the lock is released.

[0094] In S24, as events in sleep mode, the main assumptions are [Scenario 1] when the driver wants to board the vehicle via the SBW system 901, or has already boarded the vehicle, and [Scenario 2] when a suspicious person boards the vehicle and wants to move the steering wheel 91. For Scenario 1, ... Figure 12 The same example applies to preventing the steering wheel 91 from spinning freely. In case 2, the steering wheel needs to be locked again to prevent the vehicle from being stolen.

[0095] In S24, the steering wheel lock calculation unit 75 determines whether there is a change in the rotation angle of the steering control motor 78 or an input of steering wheel torque Th, or whether a start trigger has been received from the vehicle. Examples of start triggers under scenario 1 include signals such as remote operation of the driver's smart key, vehicle unlocking, door opening, and driver authentication. Examples of start triggers under scenario 2 include signals such as vehicle unlocking, door opening, suspicious person check, anti-theft device alarm, vibration sensor check, electric tilting action, and key not checked.

[0096] If the condition is true in S24, the steering control devices 201 and 202 are activated in S25, and in S26, they function as activation functions, such as confirming the steering angle detection function. In particular, by receiving a remote operation signal from the smart key as a activation trigger and pre-confirming the activation function, the waiting time until the function starts can be shortened. After S26, in S27, the steering wheel lock calculation unit 75 starts steering wheel lock drive control. By relocking the steering wheel in this way, the steering wheel free-spinning prevention and vehicle theft prevention functions of the SBW system 901 can be achieved.

[0097] (Other implementation methods)

[0098] (a) The rotation angle control, reverse torque output, and electrical angle fixed control methods shown in the first to third embodiments are not limited to selecting any one of them, and can also be configured to combine two or more control methods. For example, a control adjustment unit can be set up to perform processing such as prioritizing any one control method according to the scenario, or performing weighted averaging on multiple control outputs.

[0099] (b) The start trigger and release trigger received by the steering wheel lock calculation unit from the vehicle are not limited to the signals exemplified in the above embodiments, as long as they are signals that can be used for start / release processing. In addition, the start / release trigger can be customized according to the specifications of the vehicle or optional specifications.

[0100] (c) This disclosure is further expanded in its application through coordinated control with other systems of the vehicle. For example, even in the event of an attempted vehicle theft, it is possible to track the actions of a suspect by analyzing the movements of the steering wheel lock arithmetic unit while the vehicle is parked, thus aiding in criminal investigation.

[0101] (d) In embodiments where the energized phase is changed according to the electrical angle of the dq-axis current vector and the energizing time, a multi-phase motor other than a three-phase motor can also be used as the steering control motor. Furthermore, besides these embodiments, the steering control motor is not limited to a multi-phase motor; a DC motor can also be used. When using a DC motor, an H-bridge circuit is used as the power converter instead of an inverter.

[0102] This disclosure is not limited to such implementations and can be implemented in various ways without departing from its spirit.

[0103] The control unit and method described herein may also be implemented by a special-purpose computer configured with a processor and memory programmed to perform one or more functions embodied in a computer program. Alternatively, the control unit and method described herein may be implemented by a special-purpose computer configured with a processor composed of one or more special-purpose hardware logic circuits. Alternatively, the control unit and method described herein may be implemented by one or more special-purpose computers configured with a combination of a processor and memory programmed to perform one or more functions and a processor composed of one or more hardware logic circuits. Furthermore, the computer program may also be stored as instructions executable by the computer on a non-transferable tangible recording medium readable by the computer.

[0104] This disclosure is based on embodiments. However, this disclosure is not limited to these embodiments and structures. This disclosure also includes various modifications and variations within the same scope. In addition, various combinations, methods, and even other combinations and methods containing only one element, more or fewer elements are included in the scope and concept of this disclosure.

Claims

1. A steering control device, wherein the steering control device is applied to a steer-by-wire system in which the steering control mechanism and the steering mechanism are mechanically separated, or to an electric power steering system in which the steering control mechanism and the steering mechanism are mechanically combined, and controls the drive of the steering control motor, wherein, The aforementioned steering motor functions as a reaction force motor that imparts a reaction torque to the steering wheel in a wired steering system, or as a steering assist motor that imparts a steering assist torque to the steering wheel in an electric power steering system. The aforementioned steering control device includes: The steering wheel lock calculation unit implements steering wheel lock drive control when the conditions specified in the parking position are met. The steering wheel lock drive control is to calculate the drive command to control the locking torque that maintains the rotation of the steering wheel in a stopped state by energizing the steering control motor. as well as The power converter converts the power supply according to the drive command calculated by the steering wheel lock calculation unit and supplies it to the steering motor. In the aforementioned steering wheel lock drive control, when the steering wheel rotates due to a steering wheel torque exceeding the locking torque output by the aforementioned steering control motor, The aforementioned steering wheel lock calculation unit continues the aforementioned steering wheel lock drive control to maintain the steering wheel angle after rotation.

2. The steering control device according to claim 1, wherein, The aforementioned steering wheel lock calculation unit calculates the aforementioned drive command to make the rotation angle of the aforementioned steering control motor follow the rotation angle command value.

3. The steering control device according to claim 1, wherein, The aforementioned steering wheel lock calculation unit calculates the aforementioned drive command to cause the aforementioned steering control motor to output a reverse torque that counteracts the input steering wheel torque.

4. The steering control device according to claim 1, wherein, The aforementioned steering motor is a multi-phase motor. The aforementioned steering wheel locking calculation unit calculates the aforementioned drive command by fixing the electrical angle of the dq-axis current vector that powers the aforementioned steering control motor.

5. The steering control device according to claim 2, wherein, The aforementioned steering wheel lock calculation unit uses the rotation angle of the steering motor corresponding to the limit, i.e. the end, of the steering angle as the rotation angle command value to calculate the aforementioned drive command.

6. The steering control device according to any one of claims 1 to 4, wherein, In the aforementioned steering wheel lock drive control, when the vehicle receives a drive start trigger to release the lock, The aforementioned steering wheel lock calculation unit stops the aforementioned steering wheel lock drive control to release the lock.

7. The steering control device according to any one of claims 1 to 4, wherein, When the steering wheel lockout calculation unit releases the lockout after the steering wheel lockout drive control is completed, it reduces the lockout torque output by the steering motor.

8. The steering control device according to any one of claims 1 to 4, wherein, When the engine stop or preparation signal is disconnected and the ignition switch signal is disconnected, the aforementioned steering wheel lock operation unit begins the aforementioned steering wheel lock drive control.

9. The steering control device according to any one of claims 1 to 4, wherein, Applied to steer-by-wire systems, After the driver gets into the vehicle, the aforementioned steering wheel lock calculation unit continues the aforementioned steering wheel lock drive control until the aforementioned reaction force motor becomes capable of outputting reaction force torque.

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