Steering system

Abstract

To provide a steering system that can encourage a user to gain proficiency in driving by using a virtual mode.SOLUTION: The present invention is a steer-by-wire type steering system configured to be able to switch between a normal mode and a virtual mode. A controller calculates a steering gear ratio on the basis of a predetermined gear ratio calculation rule and vehicle speed for control, in a normal mode, sets an actual vehicle speed calculated on the basis of actual vehicle speed information acquired from a vehicle as the vehicle speed for control, and calculates a target steering angle of wheels on the basis of an operation signal, the vehicle speed for control, and the steering gear ratio, and in the virtual mode, sets a virtual vehicle speed calculated on the basis of accelerator information related to the operation of an acceleration operation member acquired from the vehicle as the vehicle speed for control, and calculates a virtual target steering angle that is a target steering angle of a virtual movable body on the basis of the operation signal, the vehicle speed for control, and the steering gear ratio.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 steer-by-wire steering system, the steering gear ratio, which represents the relationship between the angle of the steering operation member and the steering angle of the wheels, is variable. The steering gear ratio varies greatly depending on the vehicle speed. Therefore, a user must become familiar with driving a vehicle equipped with this system. Therefore, it is conceivable to promote user familiarity by using a virtual mode that realizes game or simulator functions. However, it is difficult to promote user familiarity with the system using conventional games or simulators.

[0005] An object of the present invention is to provide a steering system that can promote user familiarity with driving by utilizing a virtual mode. [Means for solving the problem]

[0006] The controller of the steering system of the present invention calculates a steering gear ratio based on a predetermined gear ratio calculation rule and a control vehicle speed, and in a normal mode, sets an actual vehicle speed calculated based on actual vehicle speed information acquired from the vehicle as the control vehicle speed, and calculates a target steering angle of the wheels based on an operation signal, the control vehicle speed, and the steering gear ratio.In a virtual mode, the controller sets a virtual vehicle speed calculated based on accelerator information related to the operation of an accelerator operating member acquired from the vehicle as the control vehicle speed, and calculates a virtual target steering angle that is a target steering angle of a virtual moving body based on the operation signal, the control vehicle speed, and the steering gear ratio. [Effects of the Invention]

[0007] The steering gear ratio is generally not reflected in a simulation environment. However, according to the present invention, a virtual moving object is steered based on a target value of the steering angle that reflects the steering gear ratio. In other words, by operating in virtual mode, the user can experience changes in the steering gear ratio according to the vehicle speed, just as in normal mode. According to the present invention, it is possible to promote the user's familiarity with driving in a system with a variable steering gear ratio. [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] FIG. 2 is a conceptual diagram illustrating the functions of a controller according to the present embodiment. [Figure 3] 4 is a flowchart illustrating an example of control 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 for steering operation by the user. 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. The operating amount sensor 23 is a sensor that detects the operating amount (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 sensor 24 detects the amount of twist of a torsion bar 27, for example.

[0012] 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.

[0013] 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. Rod moving mechanism 33 of steering device 3 is a mechanism that uses steering motor 35 as a drive source to move steering rod 31 left and right. 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.

[0014] 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.

[0015] Controller 4 is a computer including one or more processors 4a and one or more memories 4b. Controller 4 is configured to control steering device 3 and reaction force applying device 25 based on an operation signal related to the operation of operating member 20 received from operating device 2 (for example, a detected value of operation amount sensor 23) and a steering angle signal related to the steering angle of wheels 11, 12 from steering device 3 (for example, a detected value of steering angle sensor 36). Operating device 2 and steering device 3 are electrically connected via controller 4. In other words, steering system 1 is a steer-by-wire steering system that converts the mechanical operation of operating member 20 by the user into an electrical signal and transmits the electrical signal to steering device 3 that is mechanically separated from operating member 20 to steer the vehicle. Note that controller 4 may be composed of two or more computers connected to each other so that they can communicate with each other. For example, controller 4 may be composed of a controller for operating device 2 and a controller for steering device 3.

[0016] (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. The normal mode is a control mode for steering a vehicle based on the operation of an operation member 20. The virtual mode is a control mode in which a virtual moving object 8a (e.g., an image of a vehicle) expressed as an image in a game or simulation is operated with the operation member 20. The virtual moving object 8a is an image.

[0017] The vehicle of this embodiment is equipped with a simulator 8. In virtual mode, the simulator 8 displays an image of the road and a virtual moving object 8a on an in-vehicle display device 80. The virtual moving object 8a and the road may be expressed, for example, from the driver's perspective or from a perspective from above the vehicle (a bird's-eye view). The simulator 8 can be considered a computer equipped with one or more processors and one or more memories. The simulator 8 and the controller 4 (and / or CAN) are connected so that only predetermined information can be communicated. The simulator 8 and the controller 4 can be considered to constitute one controller related to steering.

[0018] The controller 4 and / or the CAN transmits operation signals and the like (for example, operation information that can be read from the operation signals) to the simulator 8. The simulator 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 a state in which the virtual moving object 8a is being steered on the display device 80. 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 as a simulation or game.

[0019] The controller 4 switches between the normal mode and the virtual mode based on a user operation (instruction). The controller 4 switches the control mode when the user performs a mode change operation and a predetermined condition is satisfied.

[0020] (Setting the control vehicle speed) The controller 4 calculates the steering gear ratio based on a predetermined gear ratio calculation rule and the control vehicle speed. The steering gear ratio is the ratio of the steering amount (steering angle) of the wheels 11, 12 to the operation amount (operation angle) of the operating member. The gear ratio calculation rule is a preset rule (e.g., a map) that represents the relationship between the control vehicle speed (input) and the steering gear ratio (output). In the normal mode, the control vehicle speed is set to an actual vehicle speed calculated based on actual vehicle speed information acquired from the vehicle. The actual vehicle speed information is, for example, a detection value of wheel speed sensors 70 provided on each wheel. The actual vehicle speed can be calculated from a plurality of wheel speeds, for example.

[0021] In the virtual mode, a virtual vehicle speed calculated based on accelerator information relating to the operation of the accelerator operating member 71 acquired from the vehicle is set as the control vehicle speed. The accelerator information is, for example, the operation amount (e.g., stroke) of the accelerator operating member 71. The controller 4 and / or simulator 8 calculates a virtual vehicle speed, which is the vehicle speed of the virtual moving object 8a, based on the operation amount (and / or operation speed) of the accelerator operating member 71. The virtual vehicle speed is the vehicle speed of the virtual moving object 8a in the virtual environment. The virtual vehicle speed is determined, for example, based on a preset relationship (e.g., a map) between the operation amount and / or operation speed and the vehicle speed. The virtual vehicle speed can also be considered an estimated value of the vehicle speed based on the operation amount of the accelerator operating member 71. Note that the accelerator operating member 71 is not limited to an accelerator pedal, and may be an operating member such as a paddle arranged on the operating members 20.

[0022] (Normal mode) In normal mode, controller 4 calculates a steering gear ratio based on a gear ratio calculation rule and an actual vehicle speed, which is a control vehicle speed. The steering gear ratio is variable depending on the vehicle speed, and is set in the gear ratio calculation rule so that, for example, it is large at low speeds and small at high speeds. Controller 4 calculates a target steering angle, which is a target value for the steering angle of wheels 11, 12, based on the calculated steering gear ratio, the control vehicle speed, the operation signal, and the steering angle signal. Controller 4 supplies a control current (hereinafter also referred to as steering current) corresponding to the target steering angle to steering motor 35. The steering gear ratio and target steering angle change depending on the magnitude of the control vehicle speed.

[0023] To explain an example of calculating the operation reaction force, controller 4 calculates an angle axial force value based on the control vehicle speed and the target steering angle. The angle axial force value can be considered, for example, a force simulating self-aligning torque. When the control vehicle speed is equal to or lower than a predetermined value (when the vehicle is traveling at a low speed or stopped), a dedicated angle axial force value is set as the angle axial force value. In addition to the angle axial force value, controller 4 calculates a current axial force value based on changes in the steering current. For example, when the vehicle travels on an uneven road surface, a change in the actual steering angle can occur, resulting in a difference between the target steering angle and the actual steering angle (hereinafter also referred to as angle difference), which can cause a change in the steering current. This is because the steering load changes depending on the road surface conditions. The current axial force value is set (calculated) in accordance with such changes in the steering current to inform the user of the road surface conditions. The operation reaction force is calculated based on a mixture (a predetermined or variable mixture ratio) of the angle axial force value and the current axial force value.

[0024] In this way, in the normal mode, the control vehicle speed is used in the calculation of the steering gear ratio, the target steering angle, and the operation reaction force. The target steering angle is set based on, for example, a value obtained by multiplying the operation angle or angle difference of the operating member 20 by a gain corresponding to the steering gear ratio. Note that the operation torque may also be used in the calculation of the operation reaction force.

[0025] (Virtual Mode) In the virtual mode, controller 4 sets the steering current to a current value that does not steer wheels 11, 12, regardless of the operation signal (regardless of the action of operation member 20). As an example, in the virtual mode, controller 4 sets the steering current to 0, regardless of the operation signal. As a result, steering motor 35 is not actuated by the operation signal, and wheels 11, 12 are not steered.

[0026] In the virtual mode, controller 4 calculates a steering gear ratio based on a gear ratio calculation rule and a virtual vehicle speed, which is a vehicle speed for control. Controller 4 calculates a virtual target steering angle, which is a target value for the steering angle of virtual moving body 8a, based on the calculated steering gear ratio, vehicle speed for control, and operation signal. The virtual target steering angle is set, for example, based on a value obtained by multiplying the operation angle of operation member 20 by a gain corresponding to the steering gear ratio.

[0027] The virtual target steering angle and the target steering angle are calculated based on a common gear ratio calculation rule. That is, the virtual target steering angle is a value that reflects the variable steering gear ratio, just like the target steering angle in normal mode. According to this embodiment, virtual moving object 8a is steered based on the target value of the steering angle that reflects the steering gear ratio that is not reflected in the simulation environment. That is, by operating in virtual mode, the user can experience changes in the steering gear ratio according to the vehicle speed, which encourages the user to become familiar with driving in a system with a variable steering gear ratio.

[0028] The controller 4 and / or the CAN transmits information on the virtual target steering angle, the accelerator operation amount, and the operation amount of the brake operation member 72 to the simulator 8. Based on this information, the simulator 8 displays an image of the road and the virtual moving object 8a on the display device 80.

[0029] The operation reaction force in the virtual mode may be calculated using the angle axial force value instead of the current axial force value. The controller 4 calculates the operation reaction force based on the control vehicle speed and the operation signal. In this way, even in the virtual mode, the virtual target steering angle and the operation reaction force are calculated based on the control vehicle speed (virtual vehicle speed).

[0030] As shown in Fig. 2, the controller 4 may include, for example, a switch 41 and a filter processing unit 42 for calculating the control vehicle speed. The switch 41 receives the calculation result of the actual vehicle speed, the calculation result of the virtual vehicle speed, and a switching flag. When the control mode switches from the normal mode to the virtual mode, the switching flag switches from off to on. When the switching flag is off, the switch 41 outputs the actual vehicle speed, and when the switching flag is on, the switch 41 outputs the virtual vehicle speed.

[0031] The filter processing unit 42 is a filter circuit for suppressing a sudden change in the value between the actual vehicle speed and the virtual vehicle speed. The filter processing unit 42 may be configured to gradually change the value from the actual vehicle speed to the virtual vehicle speed or from the virtual vehicle speed to the actual vehicle speed by, for example, delaying the phase of the signal as a filter process. A known means may be used for the gradual change. Furthermore, the filter processing unit 42 may be configured to temporarily hold the value before switching and gradually approach the value after switching if the difference between the actual vehicle speed and the virtual vehicle speed is equal to or greater than a predetermined value when the switching flag is switched. Furthermore, a condition for switching the control mode may be set such that "the actual vehicle speed is 0 and the virtual vehicle speed is 0." In this case, the controller 4 does not need to include the filter processing unit 42. The switcher 41 and the filter processing unit 42 may be realized, for example, by electronic circuits.

[0032] As shown in Fig. 3, the controller 4 receives a switching flag (S1). If the switching flag is on (S2: Yes), the control vehicle speed is set to the virtual vehicle speed (S3). If the switching flag is off (S2: No), the control vehicle speed is set to the actual vehicle speed (S4). In this way, in the steering system 1, the control vehicle speed is switched in response to switching of the control mode, and the steering gear ratio is set based on a common gear ratio calculation rule. Note that the technology of the present disclosure can also be applied to moving bodies other than electric vehicles. [Explanation of symbols]

[0033] 1...Steering system, 11, 12...Wheels, 2...Operation device, 20...Operation member, 25...Reaction force applying device, 3...Steering device, 4...Controller, 8a...Virtual moving body

Claims

[Claim 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 applying device based on an operation signal related to the operation of the operating member received from the operating 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 a virtual mode in which a virtual moving object created as an image is steered based on the operation signal, The controller Calculating a steering gear ratio based on a predetermined gear ratio calculation rule and a control vehicle speed; In the normal mode, an actual vehicle speed calculated based on actual vehicle speed information acquired from the vehicle is set as the control vehicle speed, and a target steering angle of the wheels is calculated based on the operation signal, the control vehicle speed, and the steering gear ratio; In the virtual mode, a virtual vehicle speed calculated based on accelerator information relating to the operation of an accelerator operation member acquired from a vehicle is set as the control vehicle speed, and a virtual target steering angle which is a target steering angle of the virtual moving body is calculated based on the operation signal, the control vehicle speed, and the steering gear ratio. Steering system.

Images