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 Art

[0002] Recently, in a steer-by-wire type steering system in which an operation member and a steering device are mechanically separated, for example, during charging of an electric vehicle, a steering system has been developed that is configured such that a user can play a game using the operation member. For example, Japanese Patent Application Laid-Open No. 2022-1925 discloses a vehicle capable of switching an operation target by an operation unit of a steering device between a vehicle and a virtual moving body in a game. That is, such a steering system is configured to be able to switch between a normal mode in which the vehicle is an operation target and a game mode in which the virtual moving body is an operation target.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a steering system, in a game mode (which can also be called a virtual mode), in order to suppress power consumption and tire wear, it is possible to set so that the wheels do not steer in response to the operation of the steering operation member. However, in this case, when the control mode is switched from the game mode to the normal mode, a situation may occur in which the state of the steering operation member (that is, the operation angle or the target steering angle) and the state of the wheels (that is, the actual steering angle) do not correspond. 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 or vibration may occur due to a sudden increase in the current supplied to the steering device.

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

[0006] The steering system of the present invention comprises an operating device including an operating member for steering operation by a user and a reaction force applying device for applying an operating reaction force to the operating member; a steering device mechanically separated from the operating device and steering the wheels in accordance with a supplied steering current; and a controller that controls the steering device and the reaction force applying device based on an operation signal related to the operation of the operating member received from the operating 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 type 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 body 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 in which the wheels do not steer, regardless of the operation signal. When the control mode is switched from the virtual mode to the normal mode, the controller performs specific steering control and / or specific reaction force control. Specific steering control is a control that controls the steering device based on the operation signal and the steering angle signal so that the steering device steers the wheels at a lower speed than when it steers the wheels in the normal mode, so that the actual steering angle approaches the angle corresponding to the operation signal. Specific reaction force control is a control that controls the reaction force applying 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 switches from virtual mode to normal mode, the steering device attempts to steer the wheels at a slower speed (i.e., gradually) than in normal mode, and / or the reaction force device displaces the state of the operating member toward a position corresponding to the state of the wheel by operating reaction force. This suppresses the sudden supply of steering current to the steering device and the abrupt change in steering angle that may occur when the control mode switches to normal mode, and suppresses the generation of abnormal noise and vibration when the control mode is switched. [Brief explanation of the drawing]

[0008] [Figure 1] This is a diagram showing the configuration of the steering system of this embodiment. [Figure 2] This is a conceptual diagram illustrating the steering control and reaction force control of this embodiment. [Figure 3] This is a conceptual diagram illustrating the specific steering control of this embodiment. [Figure 4] This is a conceptual diagram illustrating the specific reaction force control of this embodiment. [Figure 5] This flowchart shows an example of the control flow in this embodiment. [Modes for carrying out the invention]

[0009] Hereinafter, a steering system 1, which is one embodiment of the present invention, will be described in detail with reference to the drawings. Note that the present invention can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art, in addition to the embodiments described below. The steering system 1 of this embodiment is installed in an electric vehicle, for example. In-vehicle communication is performed, for example, by CAN (car area network or controllable area network), FlexRay, or Ethernet.

[0010] As shown in Figure 1, the steering system 1 comprises an operating device 2, a steering device 3, and a controller 4. In this embodiment, the operating device 2 comprises an operating member 20, a steering shaft 21, a steering column 22, an operating amount sensor 23, an operating torque sensor 24, and a reaction force applying device 25.

[0011] The operating member 20 is a steering wheel operating member for user steering operations, such as a steering wheel. The shape of the operating member 20 is not limited to a circle like a steering wheel; it may also be a polygon, 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 the steering shaft 21. The operating member 20 and the steering shaft 21 are rotatably held by the steering column 22 in the instrument panel reinforcement.

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

[0013] The reaction force application device 25 is a device that applies an operating reaction force to the operating member 20. The reaction force application device 25 is equipped with an electric motor, which is a reaction motor 26. The reaction force application device 25 uses the reaction motor 26, supported by the steering column 22, as a power source to apply an operating reaction force to the steering operation to the operating member 20 via the steering shaft 21. The reaction force application device 25 has a general structure that includes a reduction gear, etc. The reaction motor 26 is equipped with a rotation angle sensor 26a.

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

[0015] The steering rod 31 is a component whose two ends are connected to the left and right steering knuckles 90 via tie rods 34. The housing 32 is a component that supports the steering rod 31 so that it can move from side to side, and is also fixedly held to the vehicle body.

[0016] The rod movement mechanism 33 is a mechanism for moving the steering rod 31 left and right, driven by the steering motor 35. The steering motor 35 is an electric motor that steers the wheels 11 and 12. The rod movement mechanism 33 mainly consists of a ball screw mechanism, which is composed of a ball groove screwed into the steering rod 31 and a nut that is screwed into the ball groove via bearing balls and rotated by the steering motor 35. Since it is a common structure, a detailed explanation of the rod movement mechanism 33 will be omitted.

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

[0018] The controller 4 is configured to control the steering device 3 and the reaction force applying device 25 based on an operation signal regarding the operation of the operation member 20 received from the operation device 2. The controller 4 is configured to receive a steering angle signal regarding the steering angles of the wheels 11 and 12 from the steering device 3, that is, the detection value of the steering angle sensor 36. It can be said that the controller 4 controls the steering device 3 and the reaction force applying 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 communicably 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. That is, the steering system 1 is a steer-by-wire type steering system that steers the vehicle by converting the mechanical operation of the operation member 20 by the user into an electrical signal and transmitting the electrical signal to the steering device 3 mechanically separated from the operation member 20. Note that the controller 4 may be composed of two or more communicably connected computers. 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 and 12 are steered based on an operation signal and a virtual mode in which a virtual moving body 8a created as an image is steered based on an operation signal. That is, at least two control modes are set in the steering system 1. The normal mode is a control mode for steering the vehicle based on the operation of the operation member 20. The virtual mode is, for example, a control mode in which a virtual moving body 8a (e.g., an image of a vehicle) represented by an image in a game is operated by the operation member 20. The virtual moving body 8a is created as an image that can be viewed inside the vehicle. The normal mode can also be referred to as, for example, the first mode, the main mode, or the real mode. The virtual mode can also be referred to as, for example, the second mode, the sub mode, or the game mode.

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

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

[0023] Controller 4 switches between normal mode and virtual mode based on user operation (instructions). For example, if a user selects virtual mode using a mode selection means (e.g., an operation panel) provided in the vehicle, Controller 4 confirms that predetermined switching conditions are met and then switches the vehicle's control mode from normal mode to virtual mode. Similarly, Controller 4 switches the control mode from virtual mode to normal mode based on user operation of the operation panel, etc. Controller 4 turns on the change permission flag if the user has selected virtual mode and the predetermined switching conditions are met. If the user has not selected virtual mode or the predetermined switching conditions are not met, the change permission flag remains off. Virtual mode is a control mode intended for use when the vehicle is stationary, such as while the battery of an electric vehicle is charging, and the user is expected to play a game using the operation member 20.

[0024] (Details of normal mode) In normal mode, the controller 4 controls the steering motor 35 based on the value detected by the manipulator sensor 23 (the amount or angle of operation of the operating member 20). The controller 4 calculates the target steering angle from the value detected by the manipulator sensor 23 and sets the current value of the steering current based on the angle difference, which is the difference between the target steering angle and the actual steering angle (the value detected by the steering angle sensor 36). The controller 4 supplies the set steering current to the steering motor 35.

[0025] In normal mode, the controller 4 sets the operating reaction force on the operating member 20 and controls the reaction force motor 26 based on the detected values ​​of the operating amount sensor 23 and the operating torque sensor 24. The controller 4 supplies the reaction force motor 26 with a control current (hereinafter also referred to as the reaction force current) corresponding to the set operating reaction force. In normal mode, the controller 4 sets the operating reaction force of the operating member 20 in a manner that simulates, 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 illustrate an example of calculations performed by controller 4, as shown in Figure 2, in steering control, the deviation term P is calculated by multiplying the angle difference, which is the difference between the target steering angle St and the actual steering angle Sa, by a predetermined deviation term gain Gp. Furthermore, the velocity term D is calculated by multiplying the velocity difference, which is the difference between the target steering angular velocity Vt (the time derivative of the target steering angle St) and the actual steering angular velocity Va (the time derivative of the actual steering angle Sa), by a predetermined velocity term gain Gd. Finally, the damping term M is calculated by multiplying the above velocity difference by the damping term gain Gm.

[0027] The steering torque command value Ts is calculated by subtracting the damping term M from the sum of the deviation term P and the velocity term D. The deviation term P is a calculation term that increases the steering torque as the angle difference increases. The velocity term D is a calculation term that increases the steering torque as the velocity difference increases. The damping term M is a calculation term that suppresses sudden changes in steering torque. The steering torque command value Ts is converted into a steering current command value by current feedback control, and the steering current Is corresponding to the steering current command value is supplied to the steering motor 35.

[0028] In the above calculation, other calculation terms (such as integral terms) used in known feedback control may be used as calculation terms. The velocity term D can also be called the 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 angle difference, is added to the reaction force control amount, which is set based on the detection value of the manipulated amount sensor 23, and the reaction force torque command value Tr is calculated. The compensation torque value Tc is set to increase as the angle difference increases. The control that sets the compensation torque value Tc is called deviation compensation control CD. The compensation torque value Tc is set to inform the user of the magnitude of the angle difference, i.e., the insufficient tracking of the steering motor 35 with respect to the target steering angle. The compensation torque value Tc is set from the standpoint 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 the reaction force motor 26.

[0030] To illustrate an example of how the reaction force control amount is calculated, the reaction force control amount is a value that includes 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 angular axial force value Fa. The current axial force value Fi is the operating reaction force set based on the change in steering current. For example, when a vehicle travels on an uneven road surface, a change in the actual steering angle Sa occurs, resulting in an angular difference and 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) according to such changes in steering current in order to communicate the road surface conditions to the user. By changing the operating reaction force in accordance with the change in steering current, the user can understand the road surface conditions. The current axial force value Fi can be said to be a component of feedback control, and the angular axial force value Fa can be said to be a component of feedforward control.

[0031] (Details of virtual mode) In virtual mode, the controller 4 sets the steering current to a value that does not cause the wheels 11 and 12 to steer, regardless of the operation signal (regardless of the operation of the operating member 20). It can also be said that the controller 4 sets the absolute value of the steering current to a predetermined value or less. As an example, in virtual mode, the controller 4 sets the steering current to 0 regardless of the operation signal. In other words, in virtual mode, the controller 4 is configured not to supply steering current to the steering motor 35 in principle. As a result, the steering motor 35 does not operate in response to the operation signal, and the wheels 11 and 12 do not steer. The steering current value that does not cause the wheels 11 and 12 to steer (also called the predetermined current value) can be calculated in advance by experimentation or simulation, for example, assuming 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 explained assuming that the predetermined current value is set to 0. In virtual mode, the controller 4 sets the steering torque command value Ts to 0, regardless of the values ​​of the deviation term P, the speed term D, and the damping term M. As a result, the steering current command value also becomes 0, and the steering current Is is also set to 0 (see Figure 2). As another example, the controller 4 may set the values ​​of the deviation term P, the speed term D, and the damping term M to 0 in virtual mode. As yet another example, the controller 4 may set the values ​​of the deviation term gain Gp, the speed term gain Gd, and the damping term gain Gm to 0 in virtual mode. As yet another example, the controller 4 may set the steering current command value to 0 in virtual mode. The steering current Is can also be set to 0 by these processes. Note that if the predetermined value is a value other than 0, from the viewpoint of ease of calculation, it is preferable for the controller 4 to set the steering torque command value Ts or the steering current command value to a value corresponding to the predetermined current value.

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

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

[0035] In virtual mode reaction force control, the controller 4 sets the compensation torque value Tc to a predetermined torque value regardless of the angle difference. This allows the compensation torque value Tc, which is a component unsuitable for the virtual mode, to be controlled to an appropriate value. As an example, the predetermined torque value in this embodiment is 0. In other words, in 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 perform at least one of specific steering control and specific reaction force control when the control mode switches from virtual mode to normal mode. The controller 4 performs specific steering control and / or specific reaction force control from the time the control mode switches from virtual mode to normal mode until predetermined conditions are met.

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

[0038] Specific steering control is a 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 and 12 at a lower speed than when the steering device 3 steers the wheels 11 and 12 in normal mode, so that the actual steering angle approaches the angle corresponding to the operation signal. Specific reaction force control is a control that controls the reaction force applying device based on the operation signal and the steering angle signal received from the steering device 3 regarding the actual steering angle of the wheels 11 and 12, so that the operation angle of the operation member 20 approaches the angle corresponding to the actual steering angle of the wheels 11 and 12.

[0039] (An example of specific steering control) This section describes the case where the controller 4 is configured to perform specific steering control when the control mode is switched to normal mode. Specific steering control is performed when the control mode is switched to normal mode and the target steering angle of the wheels 11 and 12 corresponding to the operating angle of the operating member 20 differs from the actual steering angle of the wheels 11 and 12, i.e., there is an angular difference. In specific steering control, the steering device 3 gradually steers the wheels 11 and 12 in order to make their actual steering angles match the target steering angles. In other words, when the control mode is switched, the controller 4 does not increase the steering current all at once to the current value corresponding to the angular difference, but increases it gradually. As a result, when the steering device 3 returns to normal mode, it attempts to steer the wheels 11 and 12 relatively slowly at a speed lower than the steering speed of the wheels 11 and 12 that occurs when an angle difference occurs in the normal mode of a stationary vehicle (hereinafter also referred to as the "normal steering speed"). The controller 4 controls the steering device 3 so that it steers the wheels 11 and 12 at a speed lower than the normal steering speed (gradually) in accordance with the angle difference.

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

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

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

[0043] After the switching flag is turned on, the variable amount Cg gradually increases and the adjustment value Sc decreases over time. As a result, the provisional target steering angle Sts gradually increases toward the target steering angle St, and the steering current Is also gradually increases. When the variable amount Cg increases to the same value as the angle difference ΔS and the adjustment value Sc becomes 0, the provisional target steering angle Sts and the target steering angle St coincide. From the time the switching flag is received until the provisional target steering angle Sts and the target steering angle St coincide, the controller 4 gradually increases the steering current Is according to the above logic. As a result, abrupt changes in the steering current Is after the control mode switches to normal mode are suppressed, and the generation of abnormal noise and vibration due to the sudden operation of the steering motor 35 is suppressed.

[0044] Furthermore, when the switching flag is turned on, the controller 4 may notify the user via display or audio means that "the position of wheels 11 and 12 is being adjusted" along with executing the specific steering control. Also, the controller 4 terminates the specific steering control when the provisional target steering angle Sts matches the target steering angle St. The provisional target steering angle Sts can also be called the specific target steering angle.

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

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

[0047] (An example of specific reaction force control) This section describes the case where the controller 4 is configured to perform specific reaction force control when the control mode switches to normal mode. In specific reaction force control, as shown in Figure 4, the controller 4 calculates the operating angle of the operating member 20 corresponding to the actual steering angle Sa as the target operating angle Wt. The controller 4 calculates the target operating angle Wt from the actual steering angle Sa by inverse calculation of the variable gear ratio calculation CR. When the switching flag is turned on, if the actual steering angle Sa and the operating angle of the operating member 20 do not correspond, i.e., if there is an angle difference ΔS, the controller 4 uses specific reaction force control to actuate the operating member 20 with an operating reaction force and rotates the operating member 20 to the angle corresponding to the actual steering angle Sa (target operating angle Wt). The reaction force current Ir (operating reaction force) is set to a value that displaces the operating member 20 to the target operating angle Wt. According to specific reaction force control, when the switching flag is turned on, the operating member 20 returns to the position corresponding to the actual steering angle Sa by the driving force of the reaction force motor 26. This suppresses the generation of abnormal noise and vibration in the steering motor 35 caused by sudden wheel steering commands to the steering device 3.

[0048] Thus, as a specific reaction force control, the controller 4 calculates the operating angle of the operating member 20 corresponding to the actual steering angle as the target operating angle Wt, and controls the reaction force application device 25 so that the operating angle of the operating member 20 matches the target operating angle Wt. When the switching flag is turned on, the controller 4 may notify the user that "the position of the operating member 20 is being adjusted" by display means or sound means, along with executing the specific reaction force control. The controller 4 may also gradually increase the reaction force current Ir (operating reaction force) toward a value corresponding to the target operating angle Wt. The driving force of the reaction force motor 26 is small compared to the driving force of the steering motor 35, so there is little possibility of abnormal noise or vibration occurring in response to a sudden increase in the reaction force current Ir.

[0049] As shown in Figure 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 representing the state of the virtual mode received last time was on, and the status flag representing the state of the virtual mode received this time was off, the switching flag changes from off to on. If the switching flag changes from off to on (S12: Yes), the controller 4 performs specific steering control and / or specific reaction force control (S13). If the switching flag remains off in the virtual mode (S12: No), the virtual mode is maintained (S14).

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

[0051] (Other control examples) The controller 4 may execute specific steering control and specific reaction force control simultaneously or in a predetermined order. For example, the controller 4 may use specific reaction force control to activate the operating member 20 and control the reaction force device 25 so that the angle difference ΔS becomes smaller by a predetermined amount, and then execute specific steering control on the reduced angle difference ΔS. In other words, specific steering control is executed based on the updated angle difference ΔS. Conversely, the controller 4 may execute specific steering control first and then specific reaction force control. In this case, specific reaction force control is executed based on the updated actual steering angle. The controller 4 may also execute specific reaction force control while executing specific steering control. In this case, the operating angle and actual steering angle are successively updated so that the angle difference ΔS becomes 0 with the execution of each control. The execution order of these controls may be set from the viewpoint of improving safety and reducing user discomfort. Furthermore, if the steering system 1 is set to prohibit the user from driving the vehicle while specific steering control or specific reaction force control is being performed, the order of both controls may be set, including from the perspective of shortening the transition time to a drivable state.

[0052] Furthermore, for example, if the operating angle of the operating member 20 is shifted to one side in the direction of rotation from the neutral position (vehicle straight-ahead position), and the actual steering angle of the wheels 11 and 12 is shifted to the other side in the direction of rotation from the neutral position, the controller 4 may execute only the specific reaction force control among the specific steering control and specific reaction force control. In such cases, from the viewpoint of improving safety and reducing user discomfort, it is considered better to operate the operating member 20 rather than steering the wheels 11 and 12. The above situations are when the operating member 20 is rotated counterclockwise (left) from the neutral position and the wheels 11 and 12 are steered to the right (right) from the neutral position, or when the operating member 20 is rotated clockwise (right) from the neutral position and the wheels 11 and 12 are steered to the left (left) from the neutral position.

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

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

[0055] Furthermore, when the control mode switches from virtual mode to normal mode, controller 4 may selectively execute specific steering control and specific reaction force control depending on the magnitude of the angle difference. In other words, controller 4 may execute "specific steering control," "specific reaction force control," or "both specific steering control and 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 allows for more situation-appropriate control.

[0056] For example, the controller 4 may be configured to perform specific steering control when the control mode switches to normal mode, if the angle difference ΔS is greater than 0 and less than or equal to a predetermined angle (0 < ΔS ≤ predetermined angle), and to perform specific reaction force control when the angle difference ΔS is greater than a predetermined angle (ΔS > predetermined angle). One approach is that when the angle difference ΔS is small, gradually changing the actual steering angle of the wheels 11 and 12 by specific steering control allows for a relatively quick transition to a drivable state. Also, when the angle difference ΔS is large, changing the state of the operating member 20 by specific reaction force control is considered preferable to steering the wheels 11 and 12, from the standpoint of improving safety and reducing user discomfort. Based on this approach, the control performed may differ depending on the magnitude of the angle difference ΔS, as described above.

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

[0058] Furthermore, the game console 8 may function, for example, as a simulator for driving training. Also, the technology of this disclosure can be applied to mobile devices other than electric vehicles. Moreover, the various controls or processes of this disclosure can be combined as appropriate. [Explanation of Symbols]

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

Claims

1. An operating device including an operating member for steering operation by the user and a reaction force applying device for applying an operating reaction force to the operating member, A steering device that is mechanically separated from the aforementioned operating device and steers the wheels in accordance with the supplied steering current, A controller that controls the steering device and the reaction force application device based on an operation signal related to the operation of the operating member received from the operating device and a steering angle signal related to the actual steering angle of the wheel received from the steering device, A steer-by-wire steering system comprising 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 body created as a video is steered based on the operation signal, wherein the system is configured to be switchable between these modes, The aforementioned controller, In the virtual mode, the steering current is configured to be set to a current value that does not cause the wheels to steer, regardless of the operation signal. When the control mode switches from the virtual mode to the normal mode, Specific steering control, which controls the steering device based on the operation signal and the steering angle signal, such that the steering device steers the wheels at a lower speed than when the steering device steers the wheels in the normal mode, so that the actual steering angle approaches the angle corresponding to the operation signal. and / or, Based on the aforementioned operation signal and steering angle signal, a specific reaction force control is performed to control the reaction force applying device so that the operating angle of the operating member approaches the angle corresponding to the actual steering angle. Steering system.

2. The controller executes the specific steering control and / or the specific reaction force control from the time the control mode switches from the virtual mode to the normal mode until the state of the wheel corresponding to the operation signal matches the state of the wheel corresponding to the steering angle signal. The steering system according to claim 1.

3. The aforementioned controller, In the aforementioned normal mode, The angle difference, which is the difference between the target steering angle based on the aforementioned control signal and the actual steering angle based on the aforementioned steering angle signal, is calculated. The current value of the steering current corresponding to the angle difference is calculated, The steering device is configured to supply the steering current corresponding to the calculated current value. 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 according to claim 1.

4. The controller sets the gradual increase in the steering current based on the operating angle of the operating member, the actual steering angle, or the angle difference. The steering system according to claim 3.

5. The controller, as the specific reaction force control, The operating angle of the operating member corresponding to the actual steering angle is calculated as the target operating angle. The reaction force application device is controlled so that the operating angle of the operating member matches the target operating angle. The steering system according to claim 1.

6. The aforementioned controller, When the control mode switches from the virtual mode to the normal mode, Depending on the magnitude of the angular difference, which is the difference between the target steering angle based on the operation signal and the actual steering angle based on the steering angle signal, the specific steering control and the specific reaction force control are selectively executed. A steering system according to any one of claims 1 to 5.

7. The aforementioned controller, When the control mode switches from the virtual mode to the normal mode, If the angle difference is greater than zero and less than or equal to a predetermined angle, the specific steering control is executed. If the angle difference is greater than the predetermined angle, the specific reaction force control is executed. The steering system according to claim 6.

8. The aforementioned controller, When the control mode switches from the virtual mode to the normal mode, If the angle difference is greater than zero and less than or equal to a predetermined angle, the specific steering control is executed. If 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. The steering system according to claim 6.

9. When the control mode switches 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 aforementioned controller, When the control mode switches from the virtual mode to the normal mode, When the operating angle of the operating member and the actual steering angle of the wheel are rotating to different sides relative to the neutral position, the specific reaction force control is executed. A steering system according to any one of claims 1 to 5.

11. The aforementioned controller, When the control mode switches from the virtual mode to the normal mode, If the operating angle of the operating member and the actual steering angle of the wheel are rotating to different sides relative to the neutral position, the specific reaction force control returns the operating angle of the operating member to the neutral position, and the specific steering control returns the actual steering angle of the wheel to the neutral position. A steering system according to any one of claims 1 to 5.

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