Steering gear

Abstract

To provide a steering apparatus having a novel configuration.SOLUTION: A steering apparatus 1 includes a steering unit 2, a turning unit 3, and a control device 4. The steering unit 2 includes a first switch 2B and a second switch 2C. The turning unit 3 includes a turning motor 31 which generates force to turn turning wheels 5. The control device 4 controls the turning motor 31 according to an operation state of the steering unit 2. When the first switch 2B or the second switch 2C is turned on, the control device 4 controls the turning motor 31 so that the turning wheels 5 are turned left or right relative to a neutral position corresponding to a straight traveling state of a vehicle, as reference. When the first switch 2B and the second switch 2C are both turned on, or when the first switch 2B and the second switch 2C are both turned off, the control device 4 controls the turning motor 31 so that positions of the turning wheels 5 are held.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a steering device. [Background technology]

[0002] Conventionally, there are steering systems that separate power transmission between the steering wheel and the steering wheels, known as steer-by-wire systems. A steering system has a steering unit with a steering wheel and a steering unit that generates the force to steer the steering wheels. The steering wheel is the operating end that the driver controls. Conventionally, various operating ends other than the steering wheel have been proposed, taking advantage of the fact that the steering unit and the steering unit are not mechanically connected. For example, Patent Documents 1 and 2 describe a steering system that uses a joystick as the operating end. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] U.S. Patent No. 5086870 [Patent Document 2] Japanese Patent Application Publication No. 8-34353 [Overview of the project] [Problems that the invention aims to solve]

[0004] In recent years, customer requirements for steering systems have become increasingly diverse, based on vehicle specifications and other factors. To meet these demands, extensive research and development is being conducted on various steering system configurations. There is a growing need for steering systems with novel configurations. [Means for solving the problem]

[0005] A steering system capable of solving the above problems is a steering unit in which power transmission to the steering wheels of a vehicle is separated, and comprises a steering unit having a first switch and a second switch, a steering unit having a motor that generates a force for steering the steering wheels, and a control device that controls the motor according to the operating state of the steering unit. When the first switch or the second switch is ON, the control device controls the motor so that the steering wheels steer to the left or right with respect to a neutral position corresponding to the straight-ahead state of the vehicle. When both the first switch and the second switch are ON or OFF, the control device controls the motor so that the position of the steering wheels is maintained.

[0006] With this configuration, the direction of travel of the vehicle can be changed by turning on either the first or second switch. Furthermore, by turning both the first and second switches on or off, the vehicle can maintain a straight-ahead or turning position. In this way, a novel steering device can be obtained in which the steering wheels can be turned through the operation of switches. Moreover, the configuration of the steering unit having the first and second switches is simple.

[0007] In the steering device described above, the control device may control the motor such that, when both the first switch and the second switch are turned off or on, the steering wheel is not in the neutral position, and the steering wheel returns to the neutral position.

[0008] With this configuration, there is no need to individually operate the first or second switch to return the steering wheel to the neutral position. The steering wheel can be easily returned to the neutral position simply by turning both the first and second switches off or on.

[0009] In the steering system described above, the control device may perform a process to change the steering angular velocity of the steering wheel in accordance with at least one of the vehicle speed detected through an on-board sensor and the rotation angle of a shaft that rotates in conjunction with the steering operation of the steering wheel.

[0010] In this configuration, the steering angular velocity of the steering wheels is changed according to at least one of the vehicle's driving state and the steering state of the steering wheels. This improves maneuverability. In the steering system described above, the control device may determine whether a counter-steering operation is being performed based on the operating state of the first switch and the second switch, and the steering direction relative to the neutral position of the steering wheel, and execute a process to change the steering angular velocity of the steering wheel according to the result of that determination.

[0011] In this configuration, the steering angular velocity of the steering wheels is changed depending on whether a counter-steering operation is being performed. This improves maneuverability. In the steering system described above, the control device may calculate a target value for a vehicle state quantity that reflects the turning state of the vehicle based on the steering state of the steering wheels, calculate a correction amount to be reflected in the steering angle of the steering wheels through the execution of feedback control that causes the actual value of the vehicle state quantity to follow the target value, and execute a process to reflect the correction amount in the steering angle.

[0012] This configuration maintains the vehicle's turning state in accordance with the steering state of the steering wheels. Therefore, for example, when driving on a banked road, the occurrence of so-called vehicle flow can be suppressed. A banked road is a straight inclined road that slopes in the direction of the vehicle width perpendicular to the direction of travel of the vehicle. Vehicle flow occurs when a vehicle is affected by the slope of the banked road, causing it to gradually descend towards the side of the banked road that is lower as the vehicle moves forward.

[0013] In the steering device described above, the control device may, when both the first switch and the second switch are turned off or on, control the motor such that, if the steering wheel is not in the neutral position, it holds the position of the steering wheel for a predetermined set time, and then returns the steering wheel to the neutral position.

[0014] In this configuration, when the steering wheel returns to the neutral position, its position is maintained for a set time. This suppresses sudden changes in vehicle behavior. In the steering device described above, the control device may, when returning the steering wheel to the neutral position, perform a process to reduce the steering angular velocity of the steering wheel for a period of time from when both the first switch and the second switch are turned off or on until a predetermined set time has elapsed.

[0015] In this configuration, when the steering wheels return to the neutral position, the steering speed of the steering wheels is reduced for a set period of time. As a result, sudden changes in vehicle behavior are suppressed. In the steering device described above, the control device may set a target rotational angular velocity of the shaft that rotates in conjunction with the steering wheel according to the operating state of the first switch and the second switch, calculate a target rotation angle of the shaft using the target rotational angular velocity and the calculation period of the control device, and control the motor so that the actual angle of the shaft follows the target rotation angle.

[0016] With this configuration, the steering angle of the steering wheels can be controlled by controlling the rotation angle of the shaft that rotates in conjunction with the steering wheels. In the steering system described above, the control device may perform filtering on the target rotational angular velocity.

[0017] This configuration smooths out the target rotational angular velocity of the shaft. As a result, the steering wheels can be turned more smoothly. In the steering system described above, the control device may perform filtering on the target rotation angle.

[0018] This configuration smooths out the target rotation angle of the shaft, allowing the steering wheels to be turned more smoothly. In the steering system described above, the control device may perform processing to visually notify the steering state of the steering wheels.

[0019] With this configuration, the vehicle driver can perceive the steering state of the steering wheels through their vision. In the steering device described above, the first switch and the second switch may be mechanical switches that switch on and off by applying an external force, or electrical switches that switch on and off through touch operation.

[0020] With this configuration, the vehicle can be steered by operating a mechanical or electrical switch. [Effects of the Invention]

[0021] According to the steering device of the present invention, a steering device having a novel configuration can be obtained. [Brief explanation of the drawing]

[0022] [Figure 1] This is a diagram illustrating the configuration of the first embodiment of the steering device. [Figure 2] This is a block diagram of a control device according to the first embodiment. [Figure 3] This is a flowchart showing the processing procedure of the control device according to the first embodiment. [Figure 4] This is a graph showing a first map that defines the relationship between the pinion angle and the target pinion angular velocity according to the first embodiment. [Figure 5] This is a graph showing a second map that defines the relationship between the pinion angle and the first gain according to the first embodiment. [Figure 6] This graph shows a third map that defines the relationship between vehicle speed and the second gain according to the first embodiment. [Figure 7] This is a block diagram of the correction processing unit according to the first embodiment. [Figure 8] This is a front view of a display device showing an example of a notification mode according to the first embodiment. [Figure 9] (a) and (b) are front views of a display device showing an example of a notification mode according to the first embodiment. [Figure 10] This is a front view of a display device showing an example of a notification mode according to the first embodiment. [Figure 11] This is a flowchart showing the processing procedure of the control device according to the second embodiment. [Figure 12] This is a flowchart showing the processing procedure of the control device according to the third embodiment. [Figure 13] This is a front view of a steering unit according to another embodiment. [Modes for carrying out the invention]

[0023] <First Embodiment> The following describes a first embodiment of the steering device. <Overall Structure> As shown in Figure 1, the steering system 1 is a steer-by-wire type steering system. The steering system 1 includes a steering unit 2, a steering unit 3, and a control device 4. The steering unit 2 is the mechanism operated by the driver when changing the direction of travel of the vehicle. The steering unit 3 is the mechanism for steering the vehicle's steering wheels 5. Mechanical power transmission between the steering unit 2 and the steering unit 3 is separated. The control device 4 controls the operation of the steering unit 3 according to the operating state of the steering unit 2.

[0024] The steering unit 2 is, for example, small enough for a driver to hold with both hands. The steering unit 2 has a housing 2A, a first switch 2B, and a second switch 2C. The housing 2A is rectangular parallelepiped. The first switch 2B and the second switch 2C are, for example, self-returning push-button switches and are provided in the housing 2A. A push-button switch is an electrical component that mechanically switches electrical signals in response to external force. A push-button switch has a push button and contacts. The push-button switch remains in an ON state with the contacts closed only while a pressing force is applied to the push button. When the pressing force applied to the push button is released, the contacts open as the push button automatically returns to its original position. The push-button switch remains in an OFF state with the contacts open when no pressing force is applied to the push button.

[0025] The first switch 2B and the second switch 2C are arranged side by side in the left-right direction when viewed from the front of the steering unit 2. The front of the housing 2A is the side of the housing 2A that faces the driver when the driver grips the steering unit 2. The left-right direction is the direction of the long side of the housing 2A. The first switch 2B is positioned so that the driver can operate it with their left thumb while gripping the first end of the housing 2A in the long side direction (the left end in Figure 1) and the second end of the housing 2A in the long side direction (the right end in Figure 1). The second switch 2C is positioned so that the driver can operate it with their right thumb while gripping the first end of the housing 2A in the long side direction and the second end of the housing 2A in the long side direction. The push buttons for the first switch 2B and the second switch 2C are provided so as to be exposed on the surface of the housing 2A.

[0026] The first switch 2B is operated when the vehicle is turned left relative to the direction of travel. The first switch 2B generates a first electrical signal S1. The first electrical signal S1 is an electrical signal indicating whether the first switch 2B is operated, that is, whether the first switch 2B is in the ON state. The second switch 2C is operated when the vehicle is turned right relative to the direction of travel. The second switch 2C generates a second electrical signal S2. The second electrical signal S2 is an electrical signal indicating whether the second switch 2C is operated, that is, whether the second switch 2C is in the ON state.

[0027] The steering unit 2 is connected to the control device 4 via a harness, for example, an electrical wire. The first electrical signal S1 generated by the first switch 2B and the second electrical signal S2 generated by the second switch 2C are transmitted to the control device 4 via the harness. The length of the harness is set to allow the driver seated in the driver's seat to handle the steering unit 2 with sufficient ease.

[0028] Alternatively, first information indicating that the first switch 2B is ON, and second information indicating that the second switch 2C is ON, may be exchanged between the steering unit 2 and the control device 4 via wireless communication. In this case, the steering unit 2 and the control device 4 are provided with communication circuits. The communication circuits include a transmitting circuit that transmits wireless signals and a receiving circuit that receives wireless signals.

[0029] The steering unit 3 comprises a pinion shaft 21, a steering shaft 22, and a housing 23. The housing 23 rotatably supports the pinion shaft 21. The housing 23 also reciprocates the steering shaft 22. The pinion shaft 21 is positioned to intersect the steering shaft 22. The pinion teeth 21a of the pinion shaft 21 mesh with the rack teeth 22a of the steering shaft 22. Tie rods 25 are connected to both ends of the steering shaft 22 via rack ends 24, which are ball joints. The ends of the tie rods 25 are connected to knuckles (not shown) to which the steering wheels 5 are assembled.

[0030] The steering unit 3 comprises a steering motor 31, a transmission mechanism 32, and a conversion mechanism 33. The steering motor 31 is the source of the steering force applied to the steering shaft 22. The steering force is the force that causes the steering wheel 5 to turn. The steering motor 31 is, for example, a three-phase brushless motor. The transmission mechanism 32 is, for example, a belt drive mechanism. The transmission mechanism 32 transmits the rotation of the steering motor 31 to the conversion mechanism 33. The conversion mechanism 33 is, for example, a ball screw mechanism. The conversion mechanism 33 converts the rotation transmitted via the transmission mechanism 32 into axial motion of the steering shaft 22.

[0031] As the steering shaft 22 moves axially, the steering angle θ of the steering wheel 5 changes. w The pinion teeth 21a of the pinion shaft 21 mesh with the rack teeth 22a of the steering shaft 22. Therefore, the pinion shaft 21 rotates in conjunction with the movement of the steering shaft 22. The pinion shaft 21 is a shaft that rotates in conjunction with the steering action of the steering wheel 5. The steering wheel 5 steers to the left or right relative to the direction of travel of the vehicle, with respect to the neutral position corresponding to the straight-ahead state of the vehicle. Steering angle θ w The sign of this parameter is, for example, negative when turning left relative to the neutral position, and positive when turning right.

[0032] The control device 4 controls the operation of the steering motor 31. The control device 4 has a processing circuit that includes one of the following three configurations A1, A2, and A3. A1. One or more processors that operate according to a computer program, which is software. A processor includes a CPU (Central Processing Unit) and memory.

[0033] A2. One or more dedicated hardware circuits, such as application-specific integrated circuits (ASICs), that perform at least some of the various processes. An ASIC includes a CPU and memory.

[0034] A3. Hardware circuit combining configurations A1 and A2. Memory is a medium readable by a computer that stores programs describing processes or instructions for the computer. In this embodiment, the computer is the CPU. Memory includes RAM (Random Access Memory) and ROM (Read Only Memory). The CPU performs various controls by executing the programs stored in memory at predetermined calculation cycles.

[0035] The control device 4 acquires the detection results from the on-board sensors. The sensors include a vehicle speed sensor 41, a rotation angle sensor 42, and a yaw rate sensor 43. The vehicle speed sensor 41 detects the vehicle speed V. The rotation angle sensor 42 is provided on the steering motor 31. The rotation angle sensor 42 detects the rotation angle θ of the steering motor 31. b The control device 4 detects the yaw rate of the vehicle. The control device 4 controls the operation of the steering motor 31 based on the operating state of the steering unit 2 and the detection results of various sensors. The control device 4 controls the power supply to the steering motor 31 so that the steering wheels 5 are steered according to the operating state of the steering unit 2.

[0036] When only the first switch 2B is on, the control device 4 controls the power supply to the steering motor 31 so that the steering wheel 5 steers to the left relative to the direction of travel of the vehicle. Also, when only the first switch 2B is on, the control device 4 controls the power supply to the steering motor 31 so that the steering wheel 5 steers at a predetermined steering angular velocity. The steering angular velocity is the steering angle θ w This is the rate of change over time.

[0037] When only the second switch 2C is on, the control device 4 controls the power supply to the steering motor 31 so that the steering wheel 5 steers to the right relative to the direction of travel of the vehicle. Also, when only the second switch 2C is on, the control device 4 controls the power supply to the steering motor 31 so that the steering wheel 5 steers at a predetermined steering angular velocity.

[0038] When both the first switch 2B and the second switch 2C are turned on, the control device 4 determines the steering angle θ at the time both switches are turned on. w The power supply to the steering motor 31 is controlled so that the steering angle θ is maintained. w Maintaining this position means that the steering position of the steering wheel 5 is maintained.

[0039] When both the first switch 2B and the second switch 2C are off, the control device 4 controls the power supply to the steering motor 31 so that the steering wheel 5 returns to the neutral position if it is not in the neutral position. The neutral position is the position of the steering wheel 5 that corresponds to the straight-ahead state of the vehicle. Also, when both the first switch 2B and the second switch 2C are off, the control device 4 controls the power supply to the steering motor 31 so that the steering wheel 5 steers at a predetermined steering angular velocity.

[0040] The control device 4 controls the operation of the in-vehicle notification device 6. The notification device 6 may include a display device that appeals to the driver's vision to notify information, an alarm device that appeals to the driver's hearing to notify information, or a somatosensory generation device that somatosensorily notifies information to the driver. The display device includes a HUD (Head Up Display), a meter panel, a display of a navigation system, and an LED (Light Emitting Diode). The alarm device includes a speaker or a buzzer. The somatosensory generation device includes a vibration device that vibrates vehicle equipment that contacts the driver, such as a seat. The control device 4 generates a notification control signal S3 for the notification device 6.

[0041] <Configuration of the control device 4> Next, the configuration of the control device 4 will be described. As shown in FIG. 2, the control device 4 includes a pinion angle calculation unit 61, a target pinion angle calculation unit 62, a pinion angle feedback control unit 63, a power supply control unit 64, and a notification control unit 65.

[0042] The pinion angle calculation unit 61 calculates the pinion angle θ based on the rotation angle θ of the steering motor 31 detected through the rotation angle sensor 42. The pinion angle θ is the rotation angle of the pinion shaft 21. The steering motor 31 and the pinion shaft 21 are interlocked via a transmission mechanism 32, a conversion mechanism 33, and a steering shaft 22. Therefore, there is a correlation between the rotation angle θ of the steering motor 31 and the pinion angle θ. Using this correlation, the pinion angle θ can be obtained from the rotation angle θ of the steering motor 31. The pinion shaft 21 meshes with the steering shaft 22. Therefore, there is also a correlation between the pinion angle θ and the movement amount of the steering shaft 22. That is, the pinion angle θ is a value that reflects the steering angle θ of the steering wheel 5. The rotation angle sensor 42 is also a sensor for detecting the pinion angle θ. b based on the rotation angle θ of the steering motor 31 detected through the rotation angle sensor 42, the pinion angle θ p is calculated. The pinion angle θ p is the rotation angle of the pinion shaft 21. The steering motor 31 and the pinion shaft 21 are interlocked via a transmission mechanism 32, a conversion mechanism 33, and a steering shaft 22. Therefore, there is a correlation between the rotation angle θ of the steering motor 31 and the pinion angle θ. Using this correlation, the pinion angle θ can be obtained from the rotation angle θ of the steering motor 31. The pinion shaft 21 meshes with the steering shaft 22. Therefore, there is also a correlation between the pinion angle θ and the movement amount of the steering shaft 22. That is, the pinion angle θ is a value that reflects the steering angle θ of the steering wheel 5. The rotation angle sensor 42 is also a sensor for detecting the pinion angle θ. <� b and the pinion angle θ <� p There is a correlation between them. Using this correlation, the pinion angle θ can be obtained from the rotation angle θ of the steering motor 31. The pinion shaft 21 meshes with the steering shaft 22. Therefore, there is also a correlation between the pinion angle θ and the movement amount of the steering shaft 22. That is, the pinion angle θ is a value that reflects the steering angle θ of the steering wheel 5. The rotation angle sensor 42 is also a sensor for detecting the pinion angle θ. <� b from the rotation angle θ of the steering motor 31, the pinion angle θ <� p can be obtained. The pinion shaft 21 meshes with the steering shaft 22. Therefore, there is also a correlation between the pinion angle θ and the movement amount of the steering shaft 22. That is, the pinion angle θ is a value that reflects the steering angle θ of the steering wheel 5. The rotation angle sensor 42 is also a sensor for detecting the pinion angle θ. <� p and the movement amount of the steering shaft 22. That is, the pinion angle θ <� p is a value that reflects the steering angle θ of the steering wheel 5. The rotation angle sensor 42 is also a sensor for detecting the pinion angle θ. <� w is a value that reflects the steering angle θ of the steering wheel 5. The rotation angle sensor 42 is also a sensor for detecting the pinion angle θ. <� p is also a sensor for detecting the pinion angle θ.

[0043] The target pinion angle calculation unit 62 calculates the target pinion angle θ according to the operating state of the steering unit 2 and the driving state of the vehicle. p * The target pinion angle θ is calculated. p * The pinion angle θ is p This is the target value. The target pinion angle calculation unit 62 receives the first electrical signal S1 and the second electrical signal S2 generated by the steering unit 2. The target pinion angle calculation unit 62 also receives the vehicle speed V detected through the vehicle speed sensor 41 and the pinion angle θ calculated by the pinion angle calculation unit 61. p The target pinion angle calculation unit 62 takes in the data. Based on the first electrical signal S1 and the second electrical signal S2, the target pinion angle calculation unit 62 determines whether the first switch 2B and the second switch 2C are in the ON state or the OFF state. Based on the determination result of the state of the first switch 2B and the second switch 2C, the target pinion angle calculation unit 62 determines the vehicle speed V and the pinion angle θ. p Using the target pinion angle θ, p * The target pinion angle θ is calculated. p * This corresponds to the target rotation angle of the shaft that rotates in conjunction with the steering action of the steering wheel 5.

[0044] The pinion angle feedback control unit 63 receives the target pinion angle θ calculated by the target pinion angle calculation unit 62. p * , and the pinion angle θ calculated by the pinion angle calculation unit 61 p The pinion angle feedback control unit 63 takes in the pinion angle θ. p The target pinion angle θ p * To follow this, the pinion angle θ p Through feedback control, the steering torque command value T p * The steering torque command value T is calculated. p * This is the target value for steering force.

[0045] The energization control unit 64 controls the steering torque command value T p * The power supply control unit 64 supplies power to the steering motor 31 according to the steering torque command value T. p * Based on this, the current command value for the steering motor 31 is calculated. The power supply control unit 64 receives the current I generated in the power supply path from the current sensor 66 provided in the power supply path to the steering motor 31. b The value of current I is detected. b The value of is the value of the current supplied to the steering motor 31. The energization control unit 64 controls the current command value and current I b The deviation from the value is calculated, and the power supply to the steering motor 31 is controlled to eliminate the deviation. As a result, the steering motor 31 controls the steering torque command value T p * It generates torque corresponding to the value.

[0046] The notification control unit 65 controls the operation of the notification device 6. The notification control unit 65 generates a notification control signal S3, which is a command to cause the notification device 6 to perform various notification operations. The notification device 6 performs various notification operations based on the notification control signal S3.

[0047] The notification control unit 65 receives the target pinion angle θ calculated by the target pinion angle calculation unit 62. p * , and the pinion angle θ calculated by the pinion angle calculation unit 61 p The notification control unit 65 receives the target pinion angle θ. p * Alternatively, the pinion angle θ p Based on this, for example, the steering state of the steering wheel 5 is displayed on the display device. In addition, the notification control unit 65 may have a function to predict the vehicle's path. In this case, the notification control unit 65 predicts, for example, the vehicle speed V and the pinion angle θ. p Based on this, the system predicts the vehicle's path and displays the predicted path on the display device. The notification control unit 65 also determines the steering angle θ of the steering wheels 5 relative to the predicted vehicle path. wIf the noise becomes too loud, the driver is notified via the notification device 6. The notification control unit 65, for example, causes a warning to be displayed on the display device. The notification control unit 65, for example, generates an alarm sound in the alarm device. The notification control unit 65, for example, generates vibrations in the sensory generation device.

[0048] Depending on the product specifications, the control device 4 may have a correction processing unit 70. The correction processing unit 70 processes the target pinion angle θ calculated by the target pinion angle calculation unit 62. p * Correction processing is performed on the result. An example of the configuration of the correction processing unit 70 is as follows.

[0049] As shown in Figure 7, the correction processing unit 70 receives the vehicle speed V detected through the vehicle speed sensor 41 and the target pinion angle θ calculated by the target pinion angle calculation unit 62. p * The correction processing unit 70 includes a target yaw rate calculation unit 71, a subtractor 72, a feedback control unit 73, and an adder 74.

[0050] The target yaw rate calculation unit 71 calculates the target pinion angle θ p * And based on the vehicle speed V, the target yaw rate YR * Calculate the target yaw rate YR. * This is the target value for the yaw rate (YR). The subtractor 72 calculates the target yaw rate YR. * The yaw rate deviation ΔYR is calculated by subtracting the yaw rate YR from the result.

[0051] The feedback control unit 73 sets the yaw rate YR detected through the yaw rate sensor 43 to the target yaw rate YR. * Through the execution of feedback control that follows the target pinion angle θ, p * Correction amount θ for pcThe feedback control unit 73 calculates the following: The feedback control unit 73 performs proportional, integral, and differential operations on the yaw rate deviation ΔYR calculated by the subtractor 72, thereby correcting the amount θ pc The following is calculated: that is, the correction amount θ. pc This is the sum of the output values ​​of the proportional element, the integral element, and the differential element, all of which take the yaw rate deviation ΔYR as input.

[0052] The adder 74 calculates a correction amount θ by the feedback control unit 73. pc The target pinion angle θ is calculated by the target pinion angle calculation unit 62. p * By adding this, the final target pinion angle θ p * Perform the calculation.

[0053] The pinion angle feedback control unit 63 sets the final target pinion angle θ. p * The actual pinion angle θ p By performing feedback control to track the correction amount θ, pc The steering angle θ that reflects this w This will be realized.

[0054] <Procedure for calculating the target pinion angle> Next, the target pinion angle θ p * The procedure for the calculation process is explained according to the flowchart in Figure 3. The process in the flowchart is executed at a predetermined calculation cycle.

[0055] As shown in the flowchart of Figure 3, the control device 4 receives the first electrical signal S1 and the second electrical signal S2 generated by the steering unit 2, as well as the vehicle speed V detected through the vehicle speed sensor 41 (step S101).

[0056] Next, the control device 4 determines, based on the first electrical signal S1 and the second electrical signal S2, whether both the first switch 2B and the second switch 2C are in the OFF state (step S102).

[0057] When it is determined that both the first switch 2B and the second switch 2C are off (YES in step S102), the control device 4 determines whether the steering wheel 5 is not in the neutral position (step S103). The control device 4 determines, for example, based on the rotation angle θ b of the steering motor 31 whether the steering wheel 5 is in the neutral position.

[0058] When it is determined that the steering wheel 5 is not in the neutral position (YES in step S103), the control device 4 calculates the target pinion angular velocity ω p * for returning the steering wheel 5 from the current position to the neutral position (step S104). The target pinion angular velocity ω p * is the target value of the pinion angular velocity, which is the rotational speed of the pinion shaft 21. The target pinion angular velocity ω p * reflects the steering speed of the steering wheel 5. The target pinion angular velocity ω p * corresponds to the target rotational angular velocity of the shaft that rotates in conjunction with the steering operation of the steering wheel 5.

[0059] The control device 4 uses the first map M1 to calculate the target pinion angular velocity ω p * . As shown in the graph of FIG. 4, the first map M1 is a three-dimensional map that defines the relationship between the absolute value of the pinion angle θ p and the absolute value of the target pinion angular velocity ω p * according to the vehicle speed V. The first map M1 has the following characteristics. That is, as the absolute value of the pinion angle θ p increases and as the vehicle speed V increases, the absolute value of the target pinion angular velocity ω p * becomes a larger value. The vehicle speed V is divided into, for example, three vehicle speed ranges. The vehicle speed ranges include a low speed range (0 km / h to less than 40 km / h), a medium speed range (40 km / h to less than 60 km / h), and a high speed range (60 km / h or more).

[0060] If the control device 4 does not determine in step 102 that both the first switch 2B and the second switch 2C are in the OFF state (NO in step S102), it proceeds to step S105.

[0061] In step S104, the control device 4 sets the target pinion angular velocity ω p * After performing the calculation, the process proceeds to step S116. In step S105, the control device 4 determines whether both the first switch 2B and the second switch 2C are turned on, based on the first electrical signal S1 and the second electrical signal S2.

[0062] When the control device 4 determines that both the first switch 2B and the second switch 2C are ON (YES in step S105), the target pinion angular velocity ω p * The value is set to "0" (step S106). Note that the control device 4 also proceeds to step S106 if it is determined in step S103 that the steering wheel 5 is in the neutral position (NO in step S103).

[0063] Next, the control device 4 processes the pinion angle θ calculated by the pinion angle calculation unit 61. p Based on this, the first gain G1 is calculated (step S107). The control device 4 uses the second map M2 to calculate the first gain G1.

[0064] As shown in the graph in Figure 5, the second map M2 has a pinion angle θ p This is a two-dimensional map that defines the relationship between the absolute value of and the first gain G1. The second map M2 has the following characteristics: that is, the pinion angle θ p The absolute value of is the first angle threshold θ p1 When the value is less than the maximum value G, the value of the first gain G1 is less than the maximum value G 11 It is maintained at the maximum value G. 11For example, this is "1". Pinion angle θ p The absolute value of is the first angle threshold θ p1 After reaching this point, the value of the first gain G1 becomes the pinion angle θ p It decreases linearly with increasing absolute value of θ. p The absolute value of is the second angle threshold θ p2 After reaching this point, the value of the first gain G1 is the minimum value G 12 It is maintained at the minimum value G. 12 For example, the maximum value G 11 It is about half the value of the first gain G1. 12 From the maximum value G 11 Within that range, it can be set in increments of, for example, "0.1".

[0065] Next, the control device 4 calculates a second gain G2 based on the vehicle speed V detected through the vehicle speed sensor 41 (step S108). The control device 4 uses the third map M3 to calculate the second gain G2.

[0066] As shown in the graph in Figure 6, the third map M3 is a two-dimensional map that defines the relationship between the vehicle speed V and the second gain G2. The third map M3 has the following characteristics: When the value of the vehicle speed V is less than the first vehicle speed threshold V1, the value of the second gain G2 is the maximum value G 21 It is maintained at the first vehicle speed threshold V1, and as the value of vehicle speed V increases, the value of the second gain G2 is at its minimum value G 22 It gradually decreases towards [the specified value]. However, as the value of the vehicle speed V increases, the slope, which is the rate of change of the second gain G2 with respect to the vehicle speed V, gradually decreases.

[0067] In step S108, the control device 4 calculates the second gain G2 and then proceeds to step S116. If the control device 4 determines in step S105 that neither the first switch 2B nor the second switch 2C is turned on (NO in step S105), it then determines whether the first switch 2B is turned on (step S106).

[0068] When the control device 4 determines that the first switch 2B is ON (YES in step S110), it determines the target pinion angular velocity ω p * The value of is set to the predetermined first setting value ω p1 * Set to (step S111). First setting value ω p1 * This is, for example, a negative value. The first setting value ω p1 * This is set, for example, in a steering system having a steering wheel, based on the steering speed when the steering wheel 5 is steered through the operation of the steering wheel. First setting value ω p1 * This is stored in the non-volatile memory of the control device 4.

[0069] In step S111, the control device 4 sets the target pinion angular velocity ω p * The value of the first setting value ω p1 * After setting this, the process proceeds through steps S107 and S108, and then to step S116.

[0070] If the control device 4 does not determine in step S110 that the first switch 2B is ON (NO in step S110), it proceeds to step S112. This is because it recognizes that the second switch 2C is ON.

[0071] In step S112, the control device 4 sets the target pinion angular velocity ω p * The value of is set to the second defined setting value ω p2 * Set to the second setting value ω p2 *The sign of is the first setting value ω p1 * The opposite is true. That is, the first set value ω p1 * When is a negative value, the second setting value ω p2 * This is a positive value. The second setting value ω p2 * This is set, for example, in a steering system having a steering wheel, based on the steering speed when the steering wheel 5 is steered through the operation of the steering wheel. Second setting value ω p2 * This is stored in the non-volatile memory of the control device 4.

[0072] In step S112, the control device 4 sets the target pinion angular velocity ω p * The value of the second setting value ω p2 * After setting this, the process proceeds through steps S107 and S108, and then to step S116.

[0073] If the control device 4 determines in step S105 that neither the first switch 2B nor the second switch 2C is in the ON state (NO in step S105), it executes the process in step S113 in parallel with the process in step S110.

[0074] In step S113, the control device 4 determines the operating state of the steering unit 2. Specifically, the control device 4 determines whether a counter-steering operation is being performed. A counter-steering operation is defined as turning the steering wheel 5 to a steering angle θ relative to the neutral position. w This is the operation of the steering unit 2 to steer in a direction that increases the absolute value of the steering wheel. The counter-steer operation is the operation of the steering unit 2 to steer in a direction that returns the steering wheel 5 to the neutral position.

[0075] The control device 4 determines, for example, that a rollback operation has been performed when either condition B1 or condition B2 is met. The control device 4 determines that a rollback operation has not been performed when neither condition B1 nor condition B2 is met.

[0076] B1. The second switch 2C for right steering is turned on, and the steering wheel 5 is steered to the left relative to the neutral position. B2. The first switch 2B for left steering is turned ON, and the steering wheel 5 is steered to the right relative to the neutral position.

[0077] The control device 4 determines the steering direction of the steering wheel 5 based, for example, on the rotation direction of the steering motor 31. When the control device 4 determines that a cutback operation is being performed (YES in step S113), it sets the cutback gain G3 as the third gain G3. 31 Set (S114) and proceed to step S116. Cutback gain G 31 This is set to a value of, for example, "1.5" or greater and "2.0" or less. (Retraction Gain G) 31 This is stored in the non-volatile memory of the control device 4.

[0078] When the control device 4 determines that no cutback operation has been performed (NO in step S113), it sets the third gain G3 to the normal gain G 32 Set the normal gain G (step S115), and proceed to step S116. 32 This is the cutoff gain G 31 A value smaller than the value of, for example, set to "1". Typical gain G 32 This is stored in the non-volatile memory of the control device 4.

[0079] In step S116, the control device 4 sets the final target pinion angular velocity ω p *The control device 4 calculates the target pinion angular velocity ω set in the preceding steps S104, S106, S111, or S112, as shown in equation (1) below. p * By multiplying this by the first gain G1, the second gain G2, and the third gain G3, the final target pinion angular velocity ω is obtained. p(n) * Perform the calculation.

[0080] ω p(n) * =ω p * ·G1·G2·G3…(1) However, "ω p(n) * The subscript "(n)" is a natural number and indicates that it is the value in this case. "·" indicates multiplication.

[0081] Next, the control device 4 calculates the final target pinion angular velocity ω calculated in step S116. p * The following steps are performed: filtering is performed (step S117), and the process moves to step S118. The filtering is, for example, performed using a first-order lag filter. The final target pinion angular velocity ω p * It is smoothed through filtering.

[0082] In step S118, the control device 4 controls the target pinion angle θ p * The control device 4 uses the following equation (2) to calculate the target pinion angle θ. p * Perform the calculation. θ p(n) * =θ p(n-1) * +ω p(n) * ·T …(2) However, "θ" p(n) * " is the target pinion angle θ p * This is the current value of "θ". p(n)* The subscript "(n)" is a natural number and indicates that it is the value in this case. p(n-1) * " is the target pinion angle θ p * This is the previous value of "θ". p(n-1) * The subscript "(n-1)" indicates that it is the previous value. p(n) * " is the final target pinion angular velocity calculated in the previous step S116. "T" is the defined calculation period.

[0083] Next, the control device 4 calculates the target pinion angle θ calculated in step S118. p * A filter is then applied (step S119), and the process proceeds to step S120. The filtering is, for example, performed using a first-order lag filter. Target pinion angle θ p * It is smoothed through filtering.

[0084] In step S120, the control device 4 controls the target pinion angle θ after filtering. p * The control device 4 corrects the target pinion angle θ calculated in the previous step S118. p * , and the target yaw rate YR based on the vehicle speed V detected through the vehicle speed sensor 41. * The control device 4 calculates the target yaw rate YR detected through the yaw rate sensor 43. * Through the execution of feedback control that follows the target pinion angle θ, p * Correction amount θ for pc The control device 4 calculates the target pinion angle θ after filtering. p * Correction amount θ pc By reflecting this, the final target pinion angle θ p * Perform the calculation.

[0085] The control device 4 sets the final target pinion angle θ p * After performing the calculation, the process will terminate. <The nature of the reporting> Next, an example of a notification method via the notification device 6 will be described.

[0086] As shown in Figure 8, the control device 4 may also notify the steering state of the steering wheel 5 through the notification device 6. The control device 4 displays, for example, a bar indicator 81 on the screen of the display device. The control device 4 notifies the steering state of the steering wheel 5 visually through the bar indicator 81. The bar indicator 81 extends in the left-right direction as viewed, for example, from the perspective of a driver seated in the driver's seat. The bar indicator 81 is divided into multiple display areas. The central display area 81A corresponds to the neutral position of the steering wheel 5. The leftmost display area 81B corresponds to the physical limit position of the steering wheel 5 when steering to the left. The rightmost display area 81C corresponds to the physical limit position of the steering wheel 5 when steering to the right. The control device 4 sets the target pinion angle θ p * Alternatively, the pinion angle θ p Based on this, the steering amount of the steering wheel 5 is recognized, and each display area is illuminated according to the steering amount. Each display area is illuminated one by one in order to the left or right, relative to the central display area 81A, according to the steering amount of the steering wheel 5. The bar indicator 81 may be a hardware display rather than being implemented in software on the display device screen.

[0087] As shown in Figure 9(a), the control device 4 may also notify the direction of the steering wheel 5 through the notification device 6. The control device 4 displays, for example, two virtual lanes 82A and a virtual steering wheel 82B on the display device screen. The control device 4 determines the target pinion angle θ p * Alternatively, the pinion angle θ p Based on this, the steering amount of the steering wheel 5 is recognized, and the direction of the virtual steering wheel 82B is changed according to the steering amount.

[0088] As shown in Figure 9(b), the control device 4 may also notify the direction of the steering wheel 5 through the notification device 6. The control device 4 displays, for example, a virtual steering wheel 82C on the display device screen. The control device 4 determines the target pinion angle θ p * Alternatively, the pinion angle θ p Based on this, the amount of steering of the steering wheel 5 is recognized, and the rotational position of the virtual steering wheel 82C is changed according to the amount of steering. From the rotational position of the virtual steering wheel 82C, it is possible to recognize the direction of the steering wheel 5.

[0089] As shown in Figure 10, if the control device 4 has a function to predict the vehicle's path, it may also notify the vehicle of the predicted path through the notification device 6. The control device 4 may notify the vehicle speed V and pinion angle θ, for example. p Based on this, the vehicle's path is predicted, and the predicted path 83 is displayed on the display device. The display device may be a HUD (head-up display). A HUD is, for example, a display that shows an image on the front windshield of a vehicle.

[0090] <Effects of the First Embodiment> The first embodiment provides the following effects: (1-1) When the first switch 2B or the second switch 2C is ON, the control device 4 controls the steering motor 31 so that the steering wheel 5 steers to the left or right with respect to the neutral position corresponding to the straight-ahead state of the vehicle. Also, when both the first switch 2B and the second switch 2C are ON, the control device 4 controls the steering motor 31 so that the position of the steering wheel 5 is maintained.

[0091] Therefore, the direction of travel of the vehicle can be changed by turning on either the first switch 2B or the second switch 2C. Furthermore, by turning on both the first switch 2B and the second switch 2C, the vehicle can be maintained in a straight-ahead or turning position. In this way, a novel steering device 1 can be obtained that controls the steering of the vehicle through the operation of switches. Moreover, the operation of the steering unit 2 is simple; only the on or off operation of the switches is required. Furthermore, the configuration of the steering unit 2 is simple.

[0092] (1-2) When both the first switch 2B and the second switch 2C are turned off, the control device 4 controls the steering motor 31 so that the steering wheel 5 returns to the neutral position if it is not in the neutral position. Therefore, it is not necessary to operate the first switch 2B or the second switch 2C individually to return the steering wheel 5 to the neutral position. The steering wheel 5 can be easily returned to the neutral position simply by turning off both the first switch 2B and the second switch 2C.

[0093] (1-3) The only information obtained from operating the steering unit 2 is that the first switch 2B and the second switch 2C are on or off. In other words, the information obtained from operating the steering unit 2 is less than the information obtained from operating the steering wheel or joystick. For this reason, it is difficult for the control device 4 to perform steering control that fully reflects the driver's intentions. Consequently, the driver may feel that it is difficult to steer the vehicle as intended.

[0094] Therefore, the control device 4 performs a process to steer the steering wheels 5 with an appropriate steering angular velocity according to the vehicle state in response to the operation of the steering unit 2. This process includes the processes shown in steps S102 to S116 of Figure 3. By steering the steering wheels 5 with an appropriate steering angular velocity according to the vehicle state, the vehicle's maneuverability can be improved. Furthermore, the vehicle behavior can be easily adjusted through the operation of the steering unit 2, which has a simple configuration. As a result, the driver can more easily steer the vehicle as intended. Safety and a sense of security are also improved.

[0095] (1-4) The control device 4 controls the vehicle speed V and the pinion angle θ. p Accordingly, a process is executed to change the steering angular velocity of the steering wheel 5. This process is performed to change the target pinion angular velocity ω set in steps S104, S106, S111, and S112. p * Then, pinion angle θ p The process includes multiplying a first gain G1 corresponding to the vehicle speed V by a second gain G2 corresponding to the vehicle speed V. With this configuration, the steering angular velocity of the steering wheel 5 is changed according to the vehicle's driving state and the steering state of the steering wheel 5. This improves maneuverability.

[0096] (1-5) The control device determines whether a counter-turn operation is being performed based on the operating status of the first switch 2B and the second switch 2C, and the steering direction relative to the neutral position of the steering wheel 5, and executes a process to change the steering angular velocity of the steering wheel 5 according to the result of the determination. This process changes the target pinion angular velocity ω set in steps S104, S106, S111, and S112. p * This includes a process of multiplying by a third gain G3 set in steps S114 and S115. With this configuration, the steering angular velocity of the steering wheel 5 is changed depending on whether a counter-steering operation is performed. This improves maneuverability.

[0097] (1-6) The control device 4 controls the target pinion angle θ calculated in step S118. p * Based on this, the target yaw rate YR * The target pinion angle θ is calculated. p * This is a vehicle state quantity that reflects the steering state of the steering wheel 5. Target yaw rate YR * This is the target value of the yaw rate YR, which is a vehicle state variable that reflects the turning state of the vehicle. The control device 4 sets the target yaw rate YR * Through the execution of feedback control that tracks the actual value of the yaw rate YR, the steering angle θ of the steering wheel 5 is controlled. wCorrection amount θ to be reflected pc The control device 4 calculates the correction amount θ. pc The steering angle θ w The process is executed to reflect the result. This process is performed to obtain the target pinion angle θ calculated in step S118. p * Correction amount θ pc This includes the process of adding [a certain value].

[0098] This configuration maintains the vehicle's turning state in accordance with the steering state of the steering wheels 5. Therefore, for example, when driving on a canted road, the occurrence of so-called vehicle flow can be suppressed. A canted road is a straight inclined road that slopes in the vehicle width direction perpendicular to the direction of travel of the vehicle. Vehicle flow occurs when a vehicle is affected by the slope of the canted road, causing it to gradually descend towards the side of the canted road that is lower as the vehicle moves forward.

[0099] (1-7) The control device 4 controls the target pinion angular velocity ω of the pinion shaft 21 according to the operating state of the first switch 2B and the second switch 2C. p * The control device 4 sets the target pinion angular velocity ω p * Using the calculation period T of the control device 4, the target pinion angle θ of the pinion shaft 21 is determined. p * The control device 4 calculates the target pinion angle θ. p * The steering motor 31 is controlled so that the actual angle of the pinion shaft 21 follows the pinion angle θ. p By controlling this, the steering angle θ of the steering wheel 5 w It can be controlled.

[0100] (1-8) In the switch-type steering unit 2, there is a concern that the switch may be instantaneously turned on or off. Therefore, the control device 4 calculates the target pinion angular velocity ω in step S116. p * A filter is applied to the target pinion angular velocity ω. p* By smoothing, the target pinion angular velocity ω p * The discontinuous changes are suppressed. As a result, the steering wheel 5 can be turned more smoothly.

[0101] (1-9) In the switch-type steering unit 2, there is a concern that the switch may be instantaneously turned on or off. The control device 4 calculates the target pinion angle θ in step S118. p * A filter is applied to the target pinion angle θ. p * By smoothing it, the target pinion angle θ p * The discontinuous changes are suppressed. As a result, the steering wheel 5 can be turned more smoothly.

[0102] (1-10) The control device 4 performs processing to visually notify the steering state of the steering wheels 5. This processing includes display control to cause the notification device 6 to display the display content shown in Figures 8 to 10. As a result, the driver of the vehicle can recognize the steering state of the steering wheels 5 visually. This also improves maneuverability.

[0103] (1-11) The first switch 2B and the second switch 2C are push-button switches that are switched on and off by applying an external force. By using mechanical switches, the driver can obtain an appropriate operating feel, for example, as tactile feedback in the fingertips.

[0104] (1-12) The steering unit 2 is a portable operating end. In addition, the steering wheels 5 steer at an appropriate steering angular velocity according to the vehicle state in response to the operation of the steering unit 2. This achieves both ease of operation of the steering unit 2 and vehicle maneuverability. This creates new added value for the steering system 1. For example, unlike a steering system with a steering wheel, the steering system 1 with the steering unit 2 does not require an expensive reaction force mechanism. This reduces product costs. Also, by utilizing the fact that the steering unit 2 is a portable operating end, a variety of driving positions can be realized. Furthermore, it is possible to take the steering unit 2 outside the vehicle or to operate the steering unit 2 outside the vehicle. However, if the steering unit 2 is connected to the control device 4 via a harness, the length of the harness should be adjusted to the extent that the steering unit 2 can be taken outside the vehicle.

[0105] <Second Embodiment> Next, a second embodiment of the steering device will be described. This embodiment basically has the same configuration as the first embodiment shown in Figures 1 to 10 above. For this reason, a detailed explanation of the same components and configurations as in the first embodiment will be omitted. In this embodiment, the target pinion angle θ p * This embodiment differs from the first embodiment in terms of the calculation processing procedure.

[0106] As shown in the flowchart of Figure 11, when the control device 4 determines that the steering wheel 5 is not in the neutral position (YES in step S103), it determines whether a predetermined set time has elapsed (step S201). The set time is, for example, less than 0.5 seconds and is stored in non-volatile memory. The criterion for measuring the set time is the time when it is determined that the steering wheel 5 is not in the neutral position.

[0107] When the control device 4 determines that the set time has elapsed (YES in step S201), it proceeds to step S116 to determine the final target pinion angular velocity ω p * Perform the calculation. If the control device 4 does not determine that the set time has elapsed (NO in step S201), it proceeds to step S106 and sets the target pinion angular velocity ω p * Set the value to "0".

[0108] Furthermore, when the first switch 2B and the second switch 2C are operated, the operation of the first switch 2B and the second switch 2C takes immediate priority. <Effects of the second embodiment> The second embodiment provides the following effects.

[0109] (2-1) If the steering wheel 5 begins to return to the neutral position at the same time as the steering operation by the first switch 2B or the second switch 2C is released, the vehicle behavior may change abruptly, which may reduce ride comfort or vehicle handling.

[0110] Therefore, for example, the following operation method can be considered. That is, when releasing the steering operation, both the first switch 2B and the second switch 2C are turned on for a short period of time, thereby changing the steering angle θ of the steering wheel 5. w This state is held for a short period of time. This short period is, for example, about the same as the set time. After this, by turning off both the first switch 2B and the second switch 2C, the steering wheel 5 begins to return to the neutral position. While this method suppresses abrupt changes in vehicle behavior, it is complex to operate and difficult to operate intuitively.

[0111] Therefore, when both the first switch 2B and the second switch 2C are turned off, the control device 4 holds the position of the steering wheel 5 for a predetermined set time if the steering wheel 5 is not in the neutral position. The control device 4 sets the target pinion angle θ p * By maintaining the value, the steering angle θ of the steering wheel 5 is maintained. wThe control device 4 maintains the steering. After a set time has elapsed, the steering motor 31 controls the steering wheel 5 to return to the neutral position. This suppresses abrupt changes in vehicle behavior when the steering operation is released. In addition, ride comfort and vehicle handling can be ensured.

[0112] <Third Embodiment> Next, a third embodiment of the steering device will be described. This embodiment basically has the same configuration as the first embodiment shown in Figures 1 to 10. For this reason, a detailed explanation of the same components and configurations as in the first embodiment will be omitted. In this embodiment, the target pinion angle θ p * This embodiment differs from the first embodiment in terms of the calculation processing procedure.

[0113] As shown in the flowchart in Figure 12, in step S104, the control device 4 sets the target pinion angular velocity ω when returning the steering wheel 5 from its current position to the neutral position. p * After performing the calculation, the process proceeds to step S202.

[0114] In step S202, the control device 4 determines whether a predetermined set time has elapsed. The set time is, for example, less than 0.5 seconds and is stored in non-volatile memory. The criterion for measuring the set time is the point at which it is determined that the steering wheel 5 is not in the neutral position.

[0115] When the control device 4 determines that the set time has elapsed (YES in step S202), it proceeds to step S116 to determine the final target pinion angular velocity ω p * Perform the calculation. If the control device 4 does not determine that the set time has elapsed (NO in step S202), it proceeds to step S203.

[0116] In step S203, the control device 4 uses the target pinion angular velocity ω calculated in the preceding step S104. p* A reduction process is performed on the target pinion angular velocity ω. p * This is a process to reduce the value of . The control device 4 calculates the target pinion angular velocity ω in step S104 as shown in equation (3) below. p * By multiplying this by the fourth gain G4, the reduced target pinion angular velocity ω p(dec) * Perform the calculation.

[0117] ω p(dec) * =ω p * · G4 …(3) The value of the fourth gain G4 is a value less than "1·0", for example, set to "0.5". In this case, the target pinion angular velocity ω calculated in step S104 is p * It is limited to half its value.

[0118] Furthermore, when the first switch 2B and the second switch 2C are operated, the operation of the first switch 2B and the second switch 2C takes immediate priority. <Effects of the Third Embodiment> The third embodiment provides the following effects.

[0119] (3-1) When both the first switch 2B and the second switch 2C are turned off, the control device 4 controls the motor so that the steering wheel 5 returns to the neutral position if the steering wheel is not in the neutral position. However, when the control device 4 returns the steering wheel 5 to the neutral position, it performs a process to reduce the steering angular velocity of the steering wheel 5 for a period of time from when both the first switch 2B and the second switch 2C are turned off until a predetermined set time has elapsed. This process includes the process in step S203 in Figure 12. That is, the target pinion angular velocity ω calculated in step S104 p *By reducing this value, the steering angular velocity of the steering wheel 5 is reduced. Therefore, when the steering wheel 5 returns to the neutral position, abrupt changes in vehicle behavior are suppressed. In addition, ride comfort and vehicle handling can be ensured.

[0120] <Other Embodiments> The first and second embodiments may be implemented with the following modifications. The shape of the housing 2A of the steering unit 2 is not limited to a rectangular parallelepiped. The shape of the housing 2A may be changed as appropriate from the viewpoint of ease of gripping or operation.

[0121] The relationship between the operation of the steering unit 2 and the control performed by the control device 4 may be changed as appropriate. For example, if both the first switch 2B and the second switch 2C are ON, the control device 4 may return the steering wheel 5 to the neutral position if the steering wheel 5 is not in the neutral position. Also, if both the first switch 2B and the second switch 2C are OFF, the control device 4 may set the steering angle θ at the time both are turned OFF. w It may be possible to retain it.

[0122] The steering unit 2 may have three switches, including a first switch 2B and a second switch 2C. In this case, the control content of the control device 4 may be determined by the combination of operations of the first switch 2B, the second switch 2C, and the third switch. For example, when both the first switch 2B and the other switches are ON, the control device 4 controls the steering angle θ. w The control device 4 may also be configured to hold the steering wheel 5 in the neutral position when both the second switch 2C and the other switches are on. Incidentally, the steering unit 2 may have four or more switches.

[0123] The switches provided in the steering unit 2 do not have to be mechanical push-button switches. It is sufficient that they can distinguish between on and off states. On corresponds to the digital signal "1". Off corresponds to the digital signal "0". For example, the switches in the steering unit may be electrical switches. An example of an electrical switch is a capacitive touch switch. A touch switch is switched on and off through a touch operation with a finger or the like. The switches include a first switch 2B and a second switch 2C.

[0124] The steering unit 2 may have a display equipped with a touch panel. In this case, the first switch 2B and the second switch 2C may be virtual switches displayed on the display. The display of virtual switches is implemented by software. Virtual switches are another example of electrical switches that are switched on and off via touch operation.

[0125] Step S107 or S108 in the flowchart of Figure 3 may be omitted depending on the product specifications, etc. • The target pinion angular velocity ω is set in steps S111 and S112 of the flowchart in Figure 3. p * The driver may be able to selectively set the value of the setting. In this case, the steering unit 2 is configured as follows, for example.

[0126] As shown in Figure 13, the steering unit 2 has, for example, a third switch 2D and a fourth switch 2E in addition to the first switch 2B and the second switch 2C. The third switch 2D and the fourth switch 2E have a similar configuration to the first switch 2B and the second switch 2C. The third switch 2D is operated to turn the vehicle to the left relative to the direction of travel, similar to the first switch 2B. The third switch 2D generates a third electrical signal indicating an on / off state. The fourth switch 2E is operated to turn the vehicle to the right relative to the direction of travel, similar to the second switch 2C. The fourth switch 2E generates a fourth electrical signal indicating an on / off state. When the third switch 2D is ON, in step S111, the control device 4 sets the target pinion angular velocity ω p * Set the value of to the third setting value. The third setting value is, for example, the first setting value ω p1 * It is a larger value than that. When the fourth switch 2E is ON, in step S112, the control device 4 sets the target pinion angular velocity ω p * Set the value of to the fourth setting value. The fourth setting value is, for example, the second setting value ω p2 * It is a larger value than that.

[0127] • The target pinion angular velocity ω is set in step S111 of the flowchart in Figure 3. p * The first setting value ω p1 * , and the target pinion angular velocity ω set in step S112 p * The second setting value ω p2 * The steering unit 2 may be configured to change according to the operating state of the steering unit 2. In this case, the steering unit 2 is configured as follows, for example. That is, the steering unit 2 has a pressure sensor that detects the force applied when operating the first switch 2B and the second switch 2C. The control device 4 sets a first set value ω according to the detection result of the pressure sensor. p1 *Or a second setting value ω p2 * The control device 4 changes the first set value ω as the force applied to the first switch 2B increases. p1 * The control device 4 increases the second set value ω as the force applied to the second switch 2C increases. p2 * Increase.

[0128] If the control device 4 is capable of detecting the lane and the yaw angle of the vehicle through an on-board camera or the like, the determination of the counter-steering operation in step S113 of the flowchart in Figure 3 may be done as follows: That is, the control device 4 determines that a counter-steering operation has been performed when either condition C1 or condition C2 is met. The control device 4 determines that a counter-steering operation has not been performed when neither condition C1 nor condition C2 is met.

[0129] C1. The second switch 2C for right steering is turned on, and the vehicle is facing left relative to the lane. C2. The first switch 2B for left steering is ON, and the vehicle is facing to the right relative to the lane.

[0130] In the flowchart of Figure 3, the processing in step S117 or step S119 may be omitted. That is, the target pinion angular velocity ω calculated in step S116. p * , and the target pinion angle θ calculated in step S118 p * You may choose to apply the filtering process to only one of the two conditions.

[0131] The correction process in step S120 of the flowchart in Figure 3 may be performed using the vehicle's lateral acceleration. Lateral acceleration is also a vehicle state quantity that reflects the vehicle's turning state. In the first map M1 shown in Figure 4, the pinion angle θ p For changes in the target pinion angular velocity ω p *I gave an example where the pinion angle θ changes nonlinearly, p The target pinion angular velocity ω in response to the change p * It may also be possible to make it change linearly.

[0132] The first map M1 shown in Figure 4 is based on the vehicle speed V or the pinion angle θ. p Regardless of the value, the target pinion angular velocity ω p * It may be possible to maintain this value at a constant level. If the control device 4 has a function to estimate the self-aligning torque based on, for example, vehicle state variables, the first map M1 shown in Figure 4 may be modified as follows: that is, the pinion angle θ p Instead, depending on the vehicle state variable used to estimate the self-aligning torque, or the self-aligning torque, the target pinion angular velocity ω p * The calculation may be performed accordingly. Self-aligning torque is the torque generated in the direction that reduces the slip angle when the steering wheel 5 is turned.

[0133] In the second map M2 shown in Figure 5, the pinion angle θ p I gave an example where the first gain G1 changes nonlinearly in response to a change in the pinion angle θ. p The first gain G1 may change linearly in response to the change.

[0134] In the second map M2 shown in Figure 5, the pinion angle θ p Alternatively, the first gain G1 may be calculated using a signal that can recognize the degree of increase or decrease in the steering angle. The signal is, for example, the time that the first switch 2B or the second switch 2C is turned ON.

[0135] In the third map M3 shown in Figure 6, an example is given where the second gain G2 changes nonlinearly in response to the change in vehicle speed V. However, the second gain G2 may also change linearly in response to the change in vehicle speed V.

[0136] The steering device 1 may have a steering wheel. When the steering unit 2 and the steering wheel coexist, the operating end to be used is switched between the steering unit 2 and the steering wheel, for example, by operating a switch provided in the driver's seat. In this case, the steering device 1 may have a reaction force mechanism that applies steering reaction force to the steering wheel. [Explanation of symbols]

[0137] 1... Steering gear 2… Steering unit 2B... First switch 2C...Second switch 3… Steering unit 4…Control device 5… Steering wheel 31... Steering motor 41…Vehicle speed sensor 42... Rotation angle sensor

Claims

1. A steering unit in which power transmission between the vehicle's steering wheels is separated, comprising a steering unit having a first switch and a second switch, A steering unit having a motor that generates force to steer the steering wheel, The system includes a control device that controls the motor according to the operating state of the steering unit, When the first switch or the second switch is turned on, the control device controls the motor such that the steering wheel steers to the left or right with respect to the neutral position corresponding to the straight-ahead state of the vehicle. When both the first switch and the second switch are on or off, the motor is controlled so that the position of the steering wheel is maintained. The control device controls the motor so that when both the first switch and the second switch are switched from on to off, or when both the first switch and the second switch are switched from off to on, the steering wheel is not in the neutral position, and the steering wheel returns to the neutral position.

2. A steering unit in which power transmission between the vehicle's steering wheels is separated, comprising a steering unit having a first switch and a second switch, A steering unit having a motor that generates force to steer the steering wheel, The system includes a control device that controls the motor according to the operating state of the steering unit, The control device is When the first switch or the second switch is ON, the motor is controlled so that the steering wheel steers to the left or right with respect to the neutral position corresponding to the straight-ahead state of the vehicle. When both the first switch and the second switch are on or off, the motor is controlled so that the position of the steering wheel is maintained. The control device controls the motor such that, when both the first switch and the second switch are switched from on to off, or when both the first switch and the second switch are switched from off to on, and the steering wheel is not in the neutral position, the motor holds the position of the steering wheel for a predetermined set time, and then the steering wheel returns to the neutral position.

3. The steering device according to claim 1, wherein the control device performs a process to change the steering angular velocity of the steering wheel according to at least one of the vehicle speed detected through an on-board sensor and the rotation angle of a shaft that rotates in conjunction with the steering operation of the steering wheel.

4. The steering device according to claim 1, wherein the control device determines whether a counter-steering operation is being performed based on the operating state of the first switch and the second switch, and the steering direction relative to the neutral position of the steering wheel, and performs a process to change the steering angular velocity of the steering wheel according to the result of the determination.

5. The steering device according to claim 1, wherein the control device calculates a target value for a vehicle state quantity that reflects the turning state of the vehicle based on the steering state of the steering wheel, calculates a correction amount to be reflected in the steering angle of the steering wheel through the execution of feedback control that causes the actual value of the vehicle state quantity to follow the target value, and performs a process to reflect the correction amount in the steering angle.

6. The steering device according to claim 1, wherein the control device, when returning the steering wheel to the neutral position, performs a process to reduce the steering angular velocity of the steering wheel for a period of time from when both the first switch and the second switch are turned off or on until a predetermined set time has elapsed.

7. The steering device according to claim 1, wherein the control device sets a target rotational angular velocity of the shaft that rotates in conjunction with the steering wheel according to the operating state of the first switch and the second switch, calculates a target rotation angle of the shaft using the target rotational angular velocity and the calculation period of the control device, and controls the motor so that the actual angle of the shaft follows the target rotation angle.

8. The steering device according to claim 7, wherein the control device performs a filter process on the target rotational angular velocity.

9. The steering device according to claim 7, wherein the control device performs a filter process with respect to the target rotation angle.

10. The steering device according to claim 1, wherein the control device performs processing to visually notify the steering state of the steering wheel.

11. The steering device according to claim 1, wherein the first switch and the second switch are mechanical switches that switch on and off by applying an external force, or electrical switches that switch on and off through touch operation.

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