Steering system

Abstract

To provide a steering system that can suppress occurrence of noise and vibration when a control mode is switched from a virtual mode to a normal mode.SOLUTION: The present invention pertains to a steer-by-wire steering system configured to be switchable between a normal mode and a virtual mode in which a virtual movable body 8a created as an image is steered based on an operation signal. When the control mode is switched from the virtual mode to the normal mode, a controller 4 executes specific steering control that controls a steering device 3 to turn wheels 11, 12 in a direction in which an actual steering angle approaches an angle corresponding to the operation signal at a speed slower than that at which the steering device 3 turns the wheels 11, 12 in the normal mode and / or specific reaction force control that controls a reaction force application device 25 so that an operation angle of an operation member 20 approaches an angle corresponding to the actual steering angle.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a steering system. [Background technology]

[0002] Recently, in a steer-by-wire steering system in which the operating member and the steering device are mechanically separated, a steering system has been developed that is configured to allow a user to play a game using the operating member, for example, while charging an electric vehicle. For example, Japanese Patent Application Laid-Open Publication No. 2022-1925 discloses a vehicle in which the object operated by the operating unit of the steering device can be switched between the vehicle and a virtual moving object in a game. In other words, such a steering system is configured to be able to switch between a normal mode in which the vehicle is the object of operation and a game mode in which the virtual moving object is the object of operation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-1925 Summary of the Invention [Problem to be solved by the invention]

[0004] In a steering system, in game mode (also known as virtual mode), it is possible to set the wheels not to turn in response to the operation of the steering operation member in order to reduce power consumption and tire wear. However, in this case, when the control mode is switched from game mode to normal mode, a situation may arise in which the state of the steering operation member (i.e., the operation angle or target steering angle) does not correspond to the state of the wheels (i.e., the actual steering angle). In this case, the steering system attempts to steer the wheels so that the actual steering angle of the wheels matches the target steering angle. At this time, there is a concern that abnormal noise and vibration may occur due to a sudden increase in current supplied to the steering device.

[0005] An object of the present invention is to provide a steering system that can suppress the occurrence of abnormal noise and vibration when the control mode is switched from the virtual mode to the normal mode. [Means for solving the problem]

[0006] The steering system of the present invention includes an operation device including an operation member for a user to operate the steering wheel and a reaction force imparting device that imparts an operation reaction force to the operation member; a steering device that is mechanically separated from the operation device and steers wheels in response to a supplied steering current; and a controller that controls the steering device and the reaction force imparting device based on an operation signal related to the movement of the operation member received from the operation device and a steering angle signal related to the actual steering angle of the wheels received from the steering device. The steering system of the present invention is a steer-by-wire steering system that is switchable between a normal mode in which the wheels are steered based on the operation signal and the steering angle signal, and a virtual mode in which a virtual moving object created as a video is steered based on the operation signal. In the virtual mode, the controller is configured to set the steering current to a current value at which the wheels do not turn regardless of the operation signal. When the control mode is switched from the virtual mode to the normal mode, the controller executes specific steering control and / or specific reaction force control. The specific steering control is control that controls the steering device based on the operation signal and the steering angle signal so that the steering device turns the wheels in a direction in which the actual steering angle approaches the angle corresponding to the operation signal at a speed lower than that at which the steering device turns the wheels in the normal mode. The specific reaction force control is control that controls the reaction force imparting device based on the operation signal and the steering angle signal so that the operation angle of the operating member approaches the angle corresponding to the actual steering angle. [Effects of the Invention]

[0007] According to the present invention, when the control mode is switched from the virtual mode to the normal mode, the steering device attempts to steer the wheels at a slower speed (i.e., gradually) than in the normal mode, and / or the reaction force applying device displaces the state of the operating member by the operation reaction force toward a position corresponding to the state of the wheels. This suppresses a sudden supply of steering current to the steering device and a sudden change in the steering angle, which may occur when the control mode is switched to the normal mode, and suppresses the generation of abnormal noise and vibration when the control mode is switched. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a configuration diagram of a steering system according to an embodiment of the present invention; [Figure 2] 3A and 3B are conceptual diagrams for explaining steering control and reaction force control according to the present embodiment. [Figure 3] FIG. 4 is a conceptual diagram for explaining the specific steering control of the present embodiment. [Figure 4] FIG. 4 is a conceptual diagram for explaining the specific reaction force control of the present embodiment. [Figure 5] 4 is a flowchart illustrating an example of a control flow according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] A steering system 1 according to one embodiment of the present invention will be described in detail below with reference to the drawings. In addition to the following examples, the present invention can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. As an example, the steering system 1 according to this embodiment is mounted on an electric vehicle. In-vehicle communication is performed using, for example, CAN (car area network or controllable area network), FlexRay, Ethernet, or the like.

[0010] 1, the steering system 1 includes an operation device 2, a steering device 3, and a controller 4. The operation device 2 of this embodiment includes an operation member 20, a steering shaft 21, a steering column 22, an operation amount sensor 23, an operation torque sensor 24, and a reaction force imparting device 25.

[0011] The operating member 20 is a handle operating member for steering operation by the user, such as a steering wheel. The shape of the operating member 20 is not limited to a circular shape like a steering wheel, but may be a polygonal shape such as a square. The operating member 20 can also be called a steering operating member. The operating member 20 is fixed to the tip of a steering shaft 21. The operating member 20 and the steering shaft 21 are rotatably held to an instrument panel reinforcement by a steering column 22.

[0012] The operation amount sensor 23 is a sensor that detects the operation amount (operation angle) of the operation member 20. The operation torque sensor 24 is a sensor that detects the operation torque of the operation member 20. The operation torque can also be said to be the operation force applied to the operation member 20 by the user. The operation torque sensor 24 detects the amount of twist of a torsion bar 27 incorporated in the steering shaft 21, for example.

[0013] The reaction force applying device 25 is a device that applies an operation reaction force to the operating member 20. The reaction force applying device 25 is equipped with a reaction force motor 26, which is an electric motor. The reaction force applying device 25 uses the reaction force motor 26 supported by the steering column 22 as a power source and applies an operation reaction force against the steering operation to the operating member 20 via the steering shaft 21. The reaction force applying device 25 has a general structure including a reducer and the like. The reaction force motor 26 is provided with a rotation angle sensor 26a.

[0014] Steering device 3 is a device that steers wheels 11, 12 (front wheels or steerable wheels). Steering device 3 is mechanically separated from operation device 2. Steering device 3 is equipped with steering motor 35, which is an electric motor as a drive source, and current sensor 351 that detects the current value of the steering current input to steering motor 35. More specifically, steering device 3 is equipped with steering rod 31, housing 32, rod moving mechanism 33, steering motor 35, current sensor 351, rotation angle sensor 352, and steering angle sensor 36.

[0015] The steering rod 31 is a member connected at both ends to left and right steering knuckles 90 via tie rods 34. The housing 32 supports the steering rod 31 so that it can move left and right, and is a member that is fixedly held to the vehicle body.

[0016] Rod moving mechanism 33 is a mechanism for moving steering rod 31 left and right using steering motor 35 as a drive source. Steering motor 35 is an electric motor that steers wheels 11, 12. Rod moving mechanism 33 mainly comprises a ball screw mechanism that is made up of a ball groove threaded into steering rod 31 and a nut that threadably engages with the ball groove via a bearing ball and is rotated by steering motor 35. Because it has a common structure, a detailed description of rod moving mechanism 33 will be omitted.

[0017] Current sensor 351 is a sensor that detects the current value of the control current (i.e., the steering current) input to steering motor 35. Rotation angle sensor 352 is a sensor that detects the rotation angle of steering motor 35. Steering angle sensor 36 is a sensor that detects the steering angle (amount of steering) of wheels 11, 12. Steering angle sensor 36 detects the amount of movement of steering rod 31 to the left and right from the neutral position.

[0018] Controller 4 is configured to control steering device 3 and reaction force imparting device 25 based on an operation signal relating to the operation of operating member 20 received from operating device 2. Controller 4 is configured to receive a steering angle signal relating to the steering angle of wheels 11, 12 from steering device 3, i.e., the detection value of steering angle sensor 36. It can be said that controller 4 controls steering device 3 and reaction force imparting device 25 based on the operation signal and the steering angle signal.

[0019] The controller 4 is a computer including one or more processors 41 and one or more memories 42. The computer can also be referred to as an electronic control unit (ECU). The controller 4 is communicatively connected to the operation device 2 and the steering device 3. The operation device 2 and the steering device 3 are electrically connected via the controller. In other words, the steering system 1 is a steer-by-wire steering system that converts the mechanical operation of the operation member 20 by the user into an electrical signal and transmits the electrical signal to the steering device 3 that is mechanically separated from the operation member 20, thereby steering the vehicle. Note that the controller 4 may be composed of two or more computers communicatively connected. For example, the controller 4 may be composed of a controller (computer) of the operation device 2 and a controller (computer) of the steering device 3.

[0020] (Control Mode) The steering system 1 is configured to be switchable between a normal mode in which the wheels 11, 12 are steered based on an operation signal and a virtual mode in which a virtual moving object 8a created as an image is steered based on the operation signal. In other words, the steering system 1 has at least two control modes set therein. The normal mode is a control mode for steering a vehicle based on the operation of the operation member 20. The virtual mode is a control mode in which, for example, a virtual moving object 8a (e.g., an image of a vehicle) represented as an image in a game is operated with the operation member 20. The virtual moving object 8a is created as an image that can be viewed inside the vehicle. The normal mode can also be referred to as, for example, a first mode, a main mode, or a real mode. The virtual mode can also be referred to as, for example, a second mode, a sub mode, or a game mode.

[0021] A display device 80 is disposed inside the vehicle. Examples of the display device 80 include an instrument panel display, a navigation system display, a windshield onto which images and the like are projected, a mobile terminal display, AR glasses, or a head-mounted display. The game console 8 may be disposed inside the vehicle, or may be disposed outside the vehicle by being connected to the vehicle via wireless communication. The game console 8 can be considered a computer having one or more processors and one or more memories. The game console 8 and the controller 4 (and / or CAN) are connected so as to be able to communicate only predetermined information.

[0022] In the virtual mode, the game machine 8 displays a virtual moving object 8a on the display device 80. The controller 4 and / or the CAN transmits an operation signal or the like (for example, operation information that can be read from the operation signal) to the game machine 8. The game machine 8 creates a display image of the virtual moving object 8a on the display device 80 based on information received from the vehicle side (for example, the CAN), and displays on the display device 80 a situation in which the virtual moving object 8a is being steered. That is, in the virtual mode, the user can steer the virtual moving object 8a displayed on the display device 80 by operating the operation member 20.

[0023] The controller 4 switches between the normal mode and the virtual mode based on a user operation (instruction). For example, when a user operates a button on a mode selection means (e.g., an operation panel) provided in the vehicle to select the virtual mode, the controller 4 confirms that a predetermined switching condition is met and then switches the vehicle's control mode from the normal mode to the virtual mode. Similarly, the controller 4 switches the control mode from the virtual mode to the normal mode based on the user's operation of the operation panel or the like. When the user selects the virtual mode and a predetermined switching condition is met, the controller 4 turns on the change permission flag. When the user does not select the virtual mode or the predetermined switching condition is not met, the change permission flag remains off. The virtual mode is a control mode intended for a user to play a game using the operation member 20 while the vehicle is stopped, for example, while the battery of an electric vehicle is being charged.

[0024] (Normal mode details) In normal mode, controller 4 controls steering motor 35 based on the detection value of operation amount sensor 23 (the operation amount or operation angle of operating member 20). Controller 4 calculates a target steering angle from the detection value of operation amount sensor 23, and sets the current value of the steering current based on the angle difference between the target steering angle and the actual steering angle (the detection value of steering angle sensor 36). Controller 4 supplies the set steering current to steering motor 35.

[0025] In the normal mode, the controller 4 sets an operation reaction force for the operating member 20 based on the detected values ​​of the operation amount sensor 23 and the operation torque sensor 24, and controls the reaction force motor 26. The controller 4 supplies a control current (hereinafter also referred to as a reaction current) according to the set operation reaction force to the reaction force motor 26. In the normal mode, the controller 4 sets the operation reaction force of the operating member 20 so as to simulate, for example, a power steering type steering system (hereinafter also referred to as a mechanically connected system) in which the operating member 20 and the steering device 3 are mechanically connected.

[0026] To explain one example of calculations by controller 4, as shown in Fig. 2, in steering control, deviation term P is calculated by multiplying an angle difference, which is the difference between target steering angle St and actual steering angle Sa, by a predetermined deviation term gain Gp. Also, velocity term D is calculated by multiplying a velocity difference, which is the difference between target steering angular velocity Vt, which is a value obtained by differentiating target steering angle St with respect to time, and actual steering angular velocity Va, which is a value obtained by differentiating actual steering angle Sa with respect to time, by a predetermined velocity term gain Gd. Also, damping term M is calculated by multiplying the velocity difference by a damping term gain Gm.

[0027] A damping term M is subtracted from the sum of a deviation term P and a speed term D to calculate a steering torque command value Ts. The deviation term P is a calculation term that increases the steering torque the larger the angle difference. The speed term D is a calculation term that increases the steering torque the larger the speed difference. The damping term M is a calculation term for suppressing a sudden change in the steering torque. The steering torque command value Ts is converted into a steering current command value by current feedback control, and a steering current Is corresponding to the steering current command value is supplied to the steering motor 35.

[0028] In the above calculations, other calculation terms (such as an integral term) used in known feedback control may be used as the calculation terms. The velocity term D can also be called a differential term. The deviation term P corresponds to the first term, the velocity term D corresponds to the second term, and the damping term M corresponds to the third term. The deviation term gain Gp corresponds to the first gain, the velocity term gain Gd corresponds to the second gain, and the damping term gain Gm corresponds to the third gain.

[0029] In reaction force control, a compensation torque value Tc set based on the angular difference is added to a reaction force control amount that is set based on the detection value of operation amount sensor 23, etc., to calculate a reaction force torque command value Tr. The compensation torque value Tc is set to increase as the angular difference increases. Control that sets the compensation torque value Tc is called deviation compensation control CD. The compensation torque value Tc is set to notify the user of the magnitude of the angular difference, i.e., the insufficient tracking of steering motor 35 with respect to the target steering angle. The compensation torque value Tc is set from the perspective of providing information to the user and suppressing operation. The reaction force control amount will be described later. The reaction force torque command value Tr is converted into a reaction force current command value by current feedback control FB, and a reaction force current Ir corresponding to the reaction force current command value is supplied to reaction force motor 26.

[0030] To explain an example of the calculation of the reaction force control amount, the reaction force control amount is a value including a separately calculated virtual axial force value Fv. The virtual axial force value Fv is calculated, for example, based on the current axial force value Fi and the angle axial force value Fa. The current axial force value Fi is an operation reaction force that is set based on changes in the steering current. For example, when a vehicle travels on an uneven road surface, a change in the actual steering angle Sa can cause an angle difference, which can result in a change in the steering current. This is because the steering load changes depending on the road surface conditions. The current axial force value Fi is set (calculated) based on such changes in the steering current to inform the user of the road surface conditions. The operation reaction force changes depending on changes in the steering current, allowing the user to understand the road surface conditions. The current axial force value Fi can be considered a feedback control component, and the angle axial force value Fa can be considered a feedforward control component.

[0031] (Virtual mode details) In the virtual mode, controller 4 sets the steering current to a current value at which wheels 11, 12 do not turn, regardless of the operation signal (regardless of the operation of operation member 20). It can also be said that controller 4 sets the absolute value of the steering current to a predetermined value or less. As an example, in the virtual mode, controller 4 sets the steering current to 0 regardless of the operation signal. In other words, in the virtual mode, controller 4 is configured not to supply a steering current to steering motor 35, as a general rule. As a result, steering motor 35 does not operate in response to an operation signal, and wheels 11, 12 are not steered. The current value of the steering current at which wheels 11, 12 do not turn (also referred to as the predetermined current value) can be calculated in advance by experiments, simulations, etc., assuming, for example, driving on a typical paved or unpaved road.

[0032] An example of the process for setting the steering current to a predetermined current value will be described assuming that the predetermined current value is set to 0. In the virtual mode, controller 4 sets steering torque command value Ts to 0 regardless of the values ​​of deviation term P, speed term D, and damping term M. As a result, the steering current command value also becomes 0, and steering current Is is also set to 0 (see FIG. 2). As another example, controller 4 may set each of the values ​​of deviation term P, speed term D, and damping term M to 0 in the virtual mode. As another example, controller 4 may set each of the values ​​of deviation term gain Gp, speed term gain Gd, and damping term gain Gm to 0 in the virtual mode. As another example, controller 4 may set the turning current command value to 0 in the virtual mode. By these processes, steering current Is can also be set to 0. If the predetermined value is a value other than 0, it is preferable that controller 4 set the turning torque command value Ts or the turning current command value to a value corresponding to the predetermined current value, from the perspective of ease of calculation.

[0033] As another example, in the virtual mode, controller 4 may set the target steering angle to a predetermined angle (constant value) regardless of the operation signal (the operation amount or operation angle of operating member 20). This results in a state where each of the calculation terms P, D, M is not output, and also a state where steering torque command value Ts is not output. In other words, even with this configuration, steering current Is can be set to 0. Note that when the target steering angular velocity is not calculated based on the target steering angle, controller 4 sets the target steering angle to a predetermined angle and sets the target steering angular velocity to 0 in the virtual mode.

[0034] When the control mode is switched from the normal mode to the virtual mode and steering torque command value Ts is set to 0, controller 4 may gradually decrease steering torque command value Ts from the value at the time of switching toward 0. In other words, controller 4 may gradually decrease steering torque command value Ts from the value in the normal mode immediately before the control mode was switched toward 0. As a means for gradual decrease, for example, a rate limit, that is, a temporal gradient constraint, or filter processing that delays the phase of a signal may be used.

[0035] In the reaction force control of the virtual mode, the controller 4 sets the compensation torque value Tc to a predetermined torque value regardless of the angle difference. This makes it possible to control the compensation torque value Tc, which is a component that is not suitable for the virtual mode, to an appropriate value. As an example, the predetermined torque value in this embodiment is 0. In other words, in the virtual mode, the controller 4 sets the compensation torque value Tc to 0 regardless of the angle difference.

[0036] (Switching from virtual mode to normal mode) The controller 4 is configured to execute at least one of the specific turning control and the specific reaction force control when the control mode is switched from the virtual mode to the normal mode. The controller 4 executes the specific turning control and / or the specific reaction force control until a predetermined condition is satisfied after the control mode is switched from the virtual mode to the normal mode.

[0037] The predetermined condition includes, for example, "the state of wheels 11, 12 corresponding to the operation signal matches the state of wheels 11, 12 corresponding to the steering angle signal." In other words, controller 4 executes the specific steering control and / or the specific reaction force control after the control mode is switched from the virtual mode to the normal mode, until the state of wheels 11, 12 corresponding to the operation signal (target steering angle) matches the state of wheels 11, 12 corresponding to the steering angle signal (actual steering angle). Note that the predetermined condition may include, instead of or in addition to the above condition, "a steering current corresponding to the operation signal is supplied to steering device 3" and / or "a predetermined time has elapsed since the switch." In this way, controller 4 executes the specific steering control and / or the specific reaction force control for a specific period after the control mode is switched from the virtual mode to the normal mode.

[0038] The specific steering control is control that controls the steering device 3 based on the operation signal and the steering angle signal so that the steering device 3 steers the wheels 11, 12 in a direction in which the actual steering angle approaches the angle corresponding to the operation signal, at a speed slower than when the steering device 3 turns the wheels 11, 12 in normal mode. The specific reaction force control is control that controls the reaction force imparting device based on the operation signal and the steering angle signal related to the actual steering angle of the wheels 11, 12 received from the steering device 3, so that the operation angle of the operating member 20 approaches the angle corresponding to the actual steering angle of the wheels 11, 12.

[0039] (An example of specific steering control) A case will be described where controller 4 is configured to execute specific steering control when the control mode is switched to the normal mode. The specific steering control is executed when, when the control mode is switched to the normal mode, the target steering angle of wheels 11, 12 corresponding to the operation angle of operating member 20 differs from the actual steering angle of wheels 11, 12, i.e., when there is an angle difference. In specific steering control, steering device 3 gradually steers wheels 11, 12 when steering wheels 11, 12 so that the actual steering angle of wheels 11, 12 matches the target steering angle. In other words, when switching the control mode, controller 4 gradually increases the steering current rather than suddenly increasing it to a current value corresponding to the angle difference. As a result, when the steering device 3 returns to the normal mode, it attempts to steer the wheels 11, 12 relatively slowly at a speed lower than the speed at which the wheels 11, 12 are steered when an angle difference occurs in the normal mode of a stopped vehicle (hereinafter also referred to as the "normal steering speed"). The controller 4 controls the steering device 3 so that the steering device 3 steers the wheels 11, 12 at a speed (gradually) lower than the normal steering speed in accordance with the angle difference.

[0040] As an example, in specific steering control, controller 4 uses a tentative target steering angle Sts instead of target steering angle St in the steering control calculation of Fig. 2. As shown in Fig. 3, tentative target steering angle Sts is calculated based on target steering angle St and angle difference ΔS. Target steering angle St is calculated based on an operation signal (operation angle of operation member 20) and a set gear ratio (variable gear ratio). Controller 4 calculates target steering angle St from the operation signal (operation angle) using variable gear ratio calculation CR. Controller 4 calculates angle difference ΔS, which is the difference between target steering angle St and actual steering angle Sa. When the control mode is switched from virtual mode to normal mode, a switching flag is changed from off to on. When the switching flag is turned on, controller 4 subtracts adjustment value Sc from target steering angle St to calculate tentative target steering angle Sts (Sts = St - Sc).

[0041] The adjustment value Sc is a value obtained by subtracting the gradual change amount Cg from the angular difference ΔS (Sc = ΔS - Cg). The gradual change amount Cg is set to increase, for example, at predetermined time intervals. The gradual change amount Cg is set, for example, based on the operation signal, the operation speed (speed of change in the operation angle) Vs of the operation member 20, the target steering angular velocity Vt, and / or the target steering angle St. For example, the rate at which the gradual change amount Cg increases is set to increase as the input element (for example, the operation speed Vs) increases. This makes it possible to set the gradual change amount Cg appropriate for the situation. The gradual change amount Cg may be set based on detection values ​​of various sensors that indicate the user's operation intention or the state of the vehicle. For example, the controller 4 increases the gradual change amount Cg at predetermined time intervals until the gradual change amount Cg reaches its maximum value (angular difference ΔS). Note that the gradual change amount Cg may be set to increase, for example, at a preset rate (increase amount / time). The rate of increase of the gradual change amount Cg may be set based on the operation speed immediately before the switching flag is turned on, for example.

[0042] The initial value of gradual change amount Cg is set to 0. Therefore, when the switching flag is turned on (immediately after switching), adjustment value Sc becomes the same value as angle difference ΔS, and temporary target steering angle Sts becomes a value obtained by subtracting angle difference ΔS from target steering angle St (initial value: Sts=St-ΔS). Controller 4 inputs the calculated temporary target steering angle Sts in place of target steering angle St in FIG. 2. As a result, immediately after the control mode is switched to the normal mode, temporary target steering angle Sts becomes the same value as actual steering angle Sa, and the difference between temporary target steering angle Sts and actual steering angle Sa becomes 0. As a result, steering current Is immediately after the control mode is switched becomes 0 or a small value.

[0043] After the switching flag is turned on, the gradual change amount Cg gradually increases and the adjustment value Sc decreases over time. As a result, temporary target steering angle Sts gradually increases toward target steering angle St, and the steering current Is also gradually increases. When the gradual change amount Cg increases to the same value as angle difference ΔS and adjustment value Sc becomes 0, temporary target steering angle Sts and target steering angle St match. Controller 4 gradually increases the steering current Is according to the above logic from when it receives the switching flag until temporary target steering angle Sts and target steering angle St match. This suppresses a sudden change in the steering current Is after the control mode is switched to the normal mode, and suppresses the generation of abnormal noise and vibration due to sudden operation of steering motor 35.

[0044] When the switching flag is turned on, the controller 4 may notify the user by display means or audio means that "the positions of the wheels 11, 12 are being adjusted" in addition to executing the specific steering control. Furthermore, when the temporary target steering angle Sts matches the target steering angle St, the controller 4 ends the specific steering control. The temporary target steering angle Sts can also be said to be the specific target steering angle.

[0045] The above processing is an example of calculation processing for specific steering control, and controller 4 may execute processing, as specific steering control, to gradually increase steering current Is toward steering current Is corresponding to angle difference ΔS. In other words, when the control mode switches from virtual mode to normal mode and steering torque command value Ts is returned from 0 to its original value (the value in normal mode), controller 4 may gradually increase steering torque command value Ts from 0. In other words, controller 4 may gradually (in stages) increase steering torque command value Ts from 0 toward its original value. As a means for gradual increase, in addition to the above, for example, a rate limit, i.e., a time gradient constraint, or filter processing that delays the phase of a signal may be used.

[0046] An example of specific steering control can be summarized as follows. In normal mode, controller 4 is configured to calculate angle difference ΔS, which is the difference between target steering angle St based on the operation signal and actual steering angle Sa based on the steering angle signal, calculate a current value of steering current Is corresponding to angle difference ΔS, and supply steering current Is corresponding to the calculated current value to steering device 3. As specific steering control, controller 4 gradually increases steering current Is supplied to steering device 3 until steering current Is reaches a current value corresponding to angle difference ΔS. The amount of gradual increase (e.g., increase per unit time) may be set based on the user's intention or the state of the vehicle, such as the operation angle of operating member 20, the actual steering angle, or the angle difference. In other words, for example, the operation angular velocity at the time of control mode switching (e.g., immediately before or after) may be calculated based on the operation angle, and the gradual increase amount may be set based on that operation angular velocity.

[0047] (An example of specific reaction force control) A case will be described in which the controller 4 is configured to execute specific reaction force control when the control mode is switched to the normal mode. In the specific reaction force control, the controller 4 calculates the operation angle of the operating member 20 corresponding to the actual steering angle Sa as the target operation angle Wt, as shown in FIG. 4. The controller 4 calculates the target operation angle Wt from the actual steering angle Sa by back-calculating the variable gear ratio calculation CR. When the switching flag is turned on, if the actual steering angle Sa and the operation angle of the operating member 20 do not correspond, i.e., if there is an angle difference ΔS, the controller 4 operates the operating member 20 with an operation reaction force by specific reaction force control, and rotates the operating member 20 to an angle corresponding to the actual steering angle Sa (target operation angle Wt). The reaction force current Ir (operation reaction force) is set to a value that displaces the operating member 20 to the target operation angle Wt. According to the specific reaction force control, when the switching flag is turned on, the driving force of the reaction force motor 26 returns the operating member 20 to a position corresponding to the actual steering angle Sa. This suppresses the generation of abnormal noise and vibration in the steering motor 35 due to a sudden wheel steering command to the steering device 3.

[0048] In this way, as specific reaction force control, controller 4 calculates the operation angle of operating member 20 corresponding to the actual steering angle as target operation angle Wt, and controls reaction force application device 25 so that the operation angle of operating member 20 coincides with target operation angle Wt. When the switching flag is turned on, controller 4 may notify the user by display means or audio means that "the position of operating member 20 is being adjusted" in addition to executing specific reaction force control. Controller 4 may also gradually increase reaction force current Ir (operation reaction force) toward a value corresponding to target operation angle Wt. The driving force of reaction force motor 26 is smaller than the driving force of steering motor 35, so there is little possibility that abnormal noise or vibration will occur due to a sudden increase in reaction force current Ir.

[0049] As shown in Fig. 5, the controller 4 receives a switching flag in the virtual mode (S11) and determines whether the switching flag has changed from off to on (S12). For example, if the status flag indicating the state of the virtual mode received last time was on and the status flag indicating the state of the virtual mode received this time was off, the switching flag changes from off to on. If the switching flag has changed from off to on (S12: Yes), the controller 4 executes specific steering control and / or specific reaction force control (S13). If the switching flag is kept off in the virtual mode (S12: No), the virtual mode is maintained (S14).

[0050] According to this embodiment, when the control mode is switched from the virtual mode to the normal mode, the steering device 3 attempts to steer the wheels at a slower speed (i.e., gradually) than in the normal mode, and / or the reaction force applying device 25 displaces the state of the operating member 20 by the operation reaction force toward a position corresponding to the state of the wheels 11, 12. This suppresses a sudden supply of a steering current to the steering device 3 and a sudden change in the steering angle, which may occur when the control mode is switched to the normal mode, and suppresses the generation of abnormal noise and vibration when the control mode is switched.

[0051] (Other control examples) Controller 4 may execute the specific steering control and the specific reaction force control simultaneously or in a predetermined order. For example, controller 4 may operate operation member 20 through the specific reaction force control to control reaction force application device 25 so as to reduce angular difference ΔS by a predetermined amount, and then execute the specific steering control for the reduced angular difference ΔS. In other words, the specific steering control is executed based on the updated angular difference ΔS. Conversely, controller 4 may execute the specific steering control first and then execute the specific reaction force control. In this case, the specific reaction force control is executed based on the updated actual steering angle. Controller 4 may also execute the specific reaction force control while executing the specific steering control. In this case, the operation angle and actual steering angle are successively updated by executing each control so that the angular difference ΔS becomes zero. The execution order of these controls may be set from the perspective of improving safety and reducing the sense of discomfort felt by the user. In addition, if the steering system 1 is configured to prohibit the user from driving the vehicle while specific steering control or specific reaction force control is being executed, the order of the two controls may be set, including from the perspective of shortening the transition time to a drivable state.

[0052] Furthermore, for example, when the operation angle of the operating member 20 deviates from the neutral position (the vehicle's straight-ahead position) to one side in the rotational direction and the actual steering angle of the wheels 11, 12 deviates from the neutral position to the other side in the rotational direction, the controller 4 may execute only the specific reaction force control out of the specific steering control and the specific reaction force control. In such a case, from the viewpoint of improving safety and reducing the sense of discomfort felt by the user, it is considered better to operate the operating member 20 rather than steering the wheels 11, 12. The above situation is a situation where the operating member 20 is in a position rotated counterclockwise (left) from the neutral position and the wheels 11, 12 are in a position steered to the right (right) from the neutral position, or a situation where the operating member 20 is in a position rotated clockwise (right) from the neutral position and the wheels 11, 12 are in a position steered to the left (left) from the neutral position.

[0053] Furthermore, in a similar situation, that is, when the operation angle of operation member 20 and the actual steering angles of wheels 11, 12 are rotating on different sides (directions) relative to the neutral position (respective neutral positions), the operation angle of operation member 20 may be returned to the neutral position by specific reaction force control, and the actual steering angles of wheels 11, 12 may be returned to the neutral position by specific steering control. In other words, in this case, controller 4 executes specific reaction force control until the operation angle of operation member 20 returns to the neutral position, and executes specific steering control until the actual steering angles of wheels 11, 12 return to the neutral position. As a result, after the control mode switches to the normal mode, operation member 20 and wheels 11, 12 are each adjusted to their neutral positions. In this control, the specific reaction force control and the specific steering control may be executed simultaneously or in a predetermined order.

[0054] Furthermore, when the control mode is switched to the normal mode, if the operating member 20 is in the neutral position and there is an angle difference ΔS, the controller 4 may execute the specific steering control. Furthermore, when the control mode is switched to the normal mode, if the wheels 11, 12 are in the neutral position and there is an angle difference ΔS, the controller 4 may execute the specific reaction force control. As a result, after the control mode is switched to the normal mode, the operating member 20 and the wheels 11, 12 are each in the neutral position.

[0055] Furthermore, when the control mode switches from the virtual mode to the normal mode, the controller 4 may selectively execute the specific steering control and the specific reaction force control depending on the magnitude of the angle difference. In other words, the controller 4 may execute the "specific steering control," the "specific reaction force control," or "both the specific steering control and the specific reaction force control (simultaneously or sequentially)" depending on the magnitude of the angle difference ΔS at the time the switching flag is turned on. This makes it possible to execute control that is more suited to the situation.

[0056] For example, when the control mode is switched to the normal mode, controller 4 may be configured to execute specific steering control if angle difference ΔS is greater than 0 and equal to or less than a predetermined angle (0<ΔS≦predetermined angle), and to execute specific reaction force control if angle difference ΔS is greater than the predetermined angle (ΔS>predetermined angle). One approach is that when angle difference ΔS is small, gradually changing the actual steering angle of wheels 11, 12 through specific steering control can relatively quickly transition to a drivable state. Also, when angle difference ΔS is large, changing the state of operation member 20 through specific reaction force control rather than steering wheels 11, 12 is considered preferable from the perspectives of improving safety and reducing discomfort to the user. Based on this approach, the control to be executed may differ depending on the magnitude of angle difference ΔS, as described above.

[0057] Furthermore, when the control mode is switched to the normal mode, controller 4 may be configured to execute specific steering control if the angular difference ΔS is greater than 0 and equal to or less than a predetermined angle (0<ΔS≦predetermined angle), and to execute specific steering control and specific reaction force control simultaneously or in a predetermined order if the angular difference ΔS is greater than the predetermined angle (ΔS>predetermined angle). For example, by executing specific reaction force control with a relatively small displacement amount (angle change amount) and executing specific steering control with a relatively large displacement amount, it is possible to shorten the time required to transition to a drivable state.

[0058] The game machine 8 may function as a simulator for driving training, for example. The technology of the present disclosure can also be applied to moving objects other than electric vehicles. The various controls or processes of the present disclosure can be combined as appropriate. [Explanation of symbols]

[0059] 1...Steering system, 11, 12...Wheels, 2...Operation device, 20...Operation member, 23...Operation amount sensor, 25...Reaction force imparting device, 3...Turning device, 35...Turning motor, 351...Current sensor, 4...Controller, 8a...Virtual moving body

Claims

1. an operating device including an operating member for a user to operate the steering wheel and a reaction force imparting device that imparts an operation reaction force to the operating member; a steering device that is mechanically separated from the operation device and that steers the wheels in response to a supplied steering current; a controller that controls the steering device and the reaction force imparting device based on an operation signal related to the operation of the operating member received from the operation device and a steering angle signal related to the actual steering angle of the wheels received from the steering device; a steer-by-wire steering system configured to be switchable between a normal mode in which the wheels are steered based on the operation signal and the steering angle signal, and a virtual mode in which a virtual moving object created as an image is steered based on the operation signal, The controller In the virtual mode, the steering current is set to a current value at which the wheels are not steered regardless of the operation signal, When the control mode is switched from the virtual mode to the normal mode, specific steering control that controls the steering device based on the operation signal and the steering angle signal so that the steering device turns the wheels in a direction in which the actual steering angle approaches an angle corresponding to the operation signal at a speed lower than that at which the steering device turns the wheels in the normal mode; and / or a specific reaction force control that controls the reaction force application device based on the operation signal and the steering angle signal so that the operation angle of the operating member approaches an angle corresponding to the actual steering angle; Steering system.

2. the controller executes the specific steering control and / or the specific reaction force control after the control mode is switched from the virtual mode to the normal mode until a state of the wheel corresponding to the operation signal and a state of the wheel corresponding to the steering angle signal match. The steering system of claim 1 .

3. The controller In the normal mode, calculating an angle difference that is a difference between the target steering angle based on the operation signal and the actual steering angle based on the steering angle signal; A current value of the steering current corresponding to the angle difference is calculated, The steering current corresponding to the calculated current value is supplied to the steering device, As the specific steering control, the steering current supplied to the steering device is gradually increased until the steering current reaches a current value corresponding to the angle difference. The steering system of claim 1 .

4. the controller sets the amount of gradual increase of the steering current based on the operation angle of the operation member, the actual steering angle, or the angle difference.

4. The steering system of claim 3.

5. The controller performs the specific reaction force control by: calculating an operation angle of the operation member corresponding to the actual steering angle as a target operation angle; controlling the reaction force application device so that the operation angle of the operation member coincides with the target operation angle; The steering system of claim 1 .

6. The controller When the control mode is switched from the virtual mode to the normal mode, selectively executing the specific steering control and the specific reaction force control depending on the magnitude of an angle difference between the target steering angle based on the operation signal and the actual steering angle based on the steering angle signal. A steering system according to any one of claims 1 to 5.

7. The controller When the control mode is switched from the virtual mode to the normal mode, When the angle difference is greater than 0 and is equal to or less than a predetermined angle, the specific steering control is executed. When the angular difference is greater than the predetermined angle, the specific reaction force control is executed.

7. The steering system of claim 6.

8. The controller When the control mode is switched from the virtual mode to the normal mode, When the angle difference is greater than 0 and is equal to or less than a predetermined angle, the specific steering control is executed. When the angle difference is greater than the predetermined angle, the specific steering control and the specific reaction force control are executed simultaneously or in a predetermined order.

7. The steering system of claim 6.

9. When the control mode is switched from the virtual mode to the normal mode, the controller executes the specific steering control and the specific reaction force control simultaneously or in a predetermined order. A steering system according to any one of claims 1 to 5.

10. The controller When the control mode is switched from the virtual mode to the normal mode, When the operation angle of the operation member and the actual steering angle of the wheels are rotating to different sides with respect to a neutral position, the specific reaction force control is executed. A steering system according to any one of claims 1 to 5.

11. The controller When the control mode is switched from the virtual mode to the normal mode, when the operation angle of the operation member and the actual steering angle of the wheels are rotating to different sides with respect to a neutral position, the operation angle of the operation member is returned to the neutral position by the specific reaction force control, and the actual steering angle of the wheels is returned to the neutral position by the specific steering control; A steering system according to any one of claims 1 to 5.

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