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WO2025069169A1 - Dispositif de commande de système de direction et procédé de commande - Google Patents

Dispositif de commande de système de direction et procédé de commande Download PDF

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Publication number
WO2025069169A1
WO2025069169A1 PCT/JP2023/034870 JP2023034870W WO2025069169A1 WO 2025069169 A1 WO2025069169 A1 WO 2025069169A1 JP 2023034870 W JP2023034870 W JP 2023034870W WO 2025069169 A1 WO2025069169 A1 WO 2025069169A1
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WO
WIPO (PCT)
Prior art keywords
steering
control
angle
torque
steering angle
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/JP2023/034870
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English (en)
Japanese (ja)
Inventor
朋之 岡田
慧 吉澤
翼 大野
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Subaru Corp
Original Assignee
Subaru Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Subaru Corp filed Critical Subaru Corp
Priority to PCT/JP2023/034870 priority Critical patent/WO2025069169A1/fr
Publication of WO2025069169A1 publication Critical patent/WO2025069169A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D6/00—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits

Definitions

  • This disclosure relates to a control device and control method for a steering system.
  • driving assistance controls such as lane keeping control and automatic driving controls that allow vehicles to drive autonomously, in which the road shape and obstacles around the vehicle are recognized to set a target driving trajectory, and the wheels are automatically steered so that the vehicle drives along the target driving trajectory.
  • driving assistance controls and automatic driving controls there is known technology that is configured to accept manual steering operations by the driver even during automatic steering control, so that the driver can correct the driving trajectory, for example to avoid sudden obstacles.
  • Patent Document 1 discloses a steering system in which, while lane keeping assistance is being performed to keep the vehicle in the center of the driving lane, the driver's intentional steering operation causes the driver's target steering angle to deviate from the driving assistance target steering angle, and the driving assistance target steering angle is calculated as the final target steering angle until the magnitude of the steering torque accordingly exceeds an intervention threshold, and once the magnitude of the steering torque exceeds a switching threshold, the driver's target steering angle is calculated as the final target steering angle as is.
  • Patent Document 2 also discloses a technology in a steer-by-wire steering system that generates a steering reaction torque that urges the steering wheel toward a neutral position in response to the self-aligning torque acting on the steered wheels when the vehicle is turning.
  • the assist torque curve which indicates the steering assist torque applied to make the steering angle (steering angle) follow the target steering angle (target steering angle)
  • the reaction torque curve which indicates the reaction torque corresponding to the self-aligning torque
  • a steering wheel operated by a driver of a vehicle and a wheel steering device for steering the wheels are provided mechanically separated from each other, and the control device controls the steering angle of the wheels based on the steering angle of the steering wheel.
  • the control device controls the steering angle based on the steering angle of the steering wheel operated by the driver, and performs a first control for applying a reaction torque to the steering wheel in response to a self-aligning torque that the wheels receive from the road surface, and a second control for applying a reaction torque to the steering wheel in response to a target steering angle based on a target steering angle by a predetermined driving assistance control.
  • a control device executes a second control that controls the steering angle and the turning angle based on the target steering angle and applies a steering assist torque to the steering wheel according to the angular difference between the target steering angle and the steering angle or the turning angle, and a switching control that releases the second control and switches to the first control as the angular difference increases while the second control is being executed, and when the angular difference increases in a state in which the steering angle or the turning angle is larger than the target steering angle, the control device switches from the second control to the first control in a state in which the difference between the steering assist torque and the reaction torque before and after switching from the second control to the first control is equal to or less than a predetermined torque difference threshold value for suppressing a preset torque fluctuation.
  • the control device controls the steering angle based on the steering angle of the steering wheel operated by the driver, and performs a first control for applying a reaction torque to the steering wheel against the operation of the steering wheel in accordance with a self-aligning torque that the wheels receive from the road surface, and a second control for applying a reaction torque to the steering wheel in accordance with a target steering angle based on a target steering angle by a predetermined driving assistance control.
  • FIG. 1 is a schematic diagram illustrating a configuration example of a vehicle equipped with a steering system according to an embodiment of the present disclosure.
  • FIG. 2 is an explanatory diagram showing a configuration example of a steering system according to the embodiment;
  • FIG. 2 is a block diagram showing an example of the configuration of a control device of the steering system according to the embodiment.
  • FIG. 4 is an explanatory diagram showing an example of an aligning torque map (aligning torque information) used in the embodiment.
  • FIG. 4 is an explanatory diagram showing an example of an assist torque map (assist torque information) used in the embodiment.
  • FIG. 11 is an explanatory diagram showing the relationship between the angle difference and the steering assist torque in a reference example.
  • FIG. 11 is an explanatory diagram showing a steering assist torque based on a target steering angle in a reference example, superimposed on an aligning torque map.
  • 4 is an explanatory diagram showing a steering assist torque based on a target steering angle according to the embodiment superimposed on an aligning torque map;
  • FIG. 5 is a flowchart showing a processing operation of a control device of the steering system according to the embodiment.
  • 5 is a flowchart showing a processing operation of a first control by the control device of the steering system according to the embodiment; 5 is a flowchart showing a processing operation of a second control by the control device of the steering system according to the embodiment; 5 is a flowchart showing a processing operation of switching control by the control device of the steering system according to the embodiment; 10 is an explanatory diagram showing an example in which the coefficient of friction of a road surface is small according to the embodiment; FIG.
  • FIG. 1 is a schematic diagram showing an example configuration of a vehicle 1.
  • the vehicle 1 shown in FIG. 1 is configured as a front-wheel drive four-wheel vehicle in which driving torque output from a driving force source 13 that generates the vehicle's driving torque is transmitted to left and right front wheels 3LF, 3RF.
  • the vehicle 1 may be a vehicle equipped with an internal combustion engine such as a gasoline engine or diesel engine as the driving force source 13, an electric vehicle equipped with a driving motor as the driving force source 13, or a hybrid electric vehicle equipped with both an internal combustion engine and a driving motor as the driving force source 13.
  • vehicle 1 may be a rear-wheel drive vehicle, a four-wheel drive vehicle, or an electric vehicle equipped with a drive motor corresponding to each wheel.
  • vehicle 1 is equipped with a secondary battery that stores power supplied to the drive motor, and a generator such as a motor or fuel cell that generates power to charge the battery.
  • the vehicle 1 is equipped with a driving force source 13, an electric steering system 30, and brake devices 7LF, 7RF, 7LR, and 7RR (hereinafter collectively referred to as "brake devices 7" unless a distinction is required) as devices used to control the driving of the vehicle 1.
  • the driving force source 13 outputs a driving torque that is transmitted to the front wheel drive shaft 5 via a front wheel differential mechanism (not shown).
  • the driving of the driving force source 13 is controlled by a vehicle control device 11 that includes one or more electronic control devices (ECU: Electronic Control Unit).
  • ECU Electronic Control Unit
  • the vehicle control device 11 controls the driving of the driving force source 3 based on the accelerator opening operated by the driver.
  • the vehicle control device 11 controls the driving of the driving force source 3 based on the target driving torque for automatic driving.
  • the electric steering system 30 includes an electric motor and a gear mechanism (not shown), and is controlled by a steering control device 60 to adjust the steering angle of the left and right front wheels 3LF, 3RF.
  • a steering control device 60 controls the steering angle of the front wheels 3LF, 3RF based on the steering angle of the steering wheel 31 by the driver.
  • the steering control device 60 also controls the steering angle of the front wheels 3LF, 3RF based on a target steering angle that is set according to the target driving trajectory.
  • Brake devices 7LF, 7RF, 7LR, and 7RR apply braking forces to the front, rear, left, and right wheels 3LF, 3RF, 3LR, and 3RR, respectively.
  • Brake devices 7 are configured, for example, as hydraulic friction brake devices, and generate a predetermined braking force by adjusting the hydraulic pressure supplied to each brake device 7. If vehicle 1 is an electric vehicle or hybrid electric vehicle, brake devices 7 are used in conjunction with regenerative braking by the drive motor. The hydraulic pressure supplied to brake devices 7 is controlled by a hydraulic control unit (not shown).
  • the vehicle 1 also includes a surrounding environment sensor 15 and a driving assistance device 17.
  • the surrounding environment sensor 15 is one or more sensors that detect information about the surrounding environment of the vehicle 1.
  • the surrounding environment sensor 15 detects the positions, distances, and speeds of obstacles such as other vehicles and pedestrians, road shapes, and travel lane boundaries, and outputs the detection result information to the driving assistance device 17.
  • the surrounding environment sensor 15 includes one or more sensors selected from the group consisting of a camera, LiDAR, radar sensor, and ultrasonic sensor.
  • the vehicle 1 includes a pair of left and right stereo cameras 15L, 15R that capture images of the area ahead of the vehicle 1 as the surrounding environment sensor 15.
  • the driving assistance device 17 uses information on obstacles and other detection results detected by the surrounding environment sensor 15 to execute driving assistance control or automatic driving control of the vehicle 1.
  • the driving assistance device 17 has at least an assistance function for automatically driving the vehicle 1 at a predetermined position in the driving lane. Examples of such assistance functions include lane keeping control or automatic driving control.
  • the driving assistance device 17 sets a target driving trajectory for the vehicle 1 to drive, sets target values for the acceleration/deceleration of the vehicle 1 and the steering angle of the steering wheel 31 so that the vehicle 1 drives along the target driving trajectory, and outputs information on the target values to the vehicle control device 11 and the steering control device 60.
  • the vehicle 1 also has tire force sensors 9L, 9R corresponding to the left and right front wheels 3LF, 3RF.
  • the tire force sensors 9L, 9R are provided at the connection between the front wheel drive shaft 5 and the front wheels 3LF, 3RF, respectively.
  • the tire force sensors 9L, 9R are load sensors that detect the load applied to each of the left and right front wheels 3LF, 3RF.
  • the tire force sensors 9L, 9R may be six-component force detectors that detect the load in each of the three axial directions of the vehicle 1, namely the longitudinal direction (x-axis), the width direction (y-axis), and the height direction (z-axis), and the moment generated around each of the three axes.
  • FIG. 2 is a schematic diagram showing an example of the configuration of an electric steering system 30.
  • the electric steering system 30 is constructed as a steer-by-wire type steering system in which a steering wheel 31 operated by the driver and a wheel steering device 40 that steers the wheels are provided mechanically separated, and the steering angle of the front wheels 3LF, 3RF is controlled based on the detected steering angle (rotation angle) of the steering wheel 31.
  • the electric steering system 30 has a steering device 33 and a wheel steering device 40 that steers the front wheels (steerable wheels) 3RFLF, 3RF.
  • the steering device 33 receives steering input from a steering wheel 31 operated by the driver.
  • the electric steering system 30 is a steer-by-wire type steering system in which the steering device 33 and the wheel steering device 40 are mechanically separated (linkless) and controlled in conjunction with each other by a steering control device 60.
  • the steering device 33 is configured with a steering wheel 31, a steering shaft 32 connected to the steering wheel 31, and a reaction motor 34 coaxially assembled at the axial center position of the steering shaft 32.
  • the reaction motor 34 is a means for applying a reaction force (rotational resistance) to the driver operating the steering wheel 31 through the steering shaft 32 and the steering wheel 31.
  • the drive of the reaction motor 34 is controlled by the steering control device 60, and the output torque of the reaction motor 34 is transmitted to the steering wheel 31 via the steering shaft 32.
  • the wheel steering device 40 is configured with a rack shaft 51 that is arranged to extend in the left-right direction of the vehicle body, and knuckle arms 53L, 53R that are connected to both ends of the rack shaft 51 via tie rods 52L, 52R, respectively.
  • the left and right front wheels 3LF, 3RF are connected to the knuckle arms 53L, 53R, respectively.
  • the rack shaft 51 is supported by the housing 49 so that it can move freely in the left-right direction of the vehicle 1.
  • a rack gear 54 is provided on the rack shaft 51.
  • a pinion gear 55 meshes with the rack gear 54.
  • a pinion shaft 56 is connected to the pinion gear 55.
  • a steering motor 57 is coaxially mounted at the axial center position of the pinion shaft 56.
  • the steering motor 57 is an electric motor that steers the left and right front wheels 3LF, 3RF, and the drive of the steering motor 57 is controlled by the steering control device 60.
  • the output torque of the steering motor 57 is transmitted to the rack shaft 51 via the pinion shaft 56, the pinion gear 55, and the rack gear 54. This causes the left and right front wheels 3LF, 3RF to be steered.
  • a clutch mechanism 37 is provided between the steering shaft 32 and the pinion shaft 56.
  • the clutch mechanism 37 is engaged by the steering control device 60 in the event of a failure of the reaction motor 34 or the turning motor 57, directly connecting the steering shaft 32 and the pinion shaft 56 and enabling the driver to turn the front wheels 3LF, 3RF.
  • the steering control device 60 receives sensor signals output from the steering angle sensor 35, steering torque sensor 36, turning angle sensor 58, and tire force sensors 9L, 9R.
  • the steering angle sensor 35 detects the steering angle (rotation angle) of the steering wheel 31.
  • the steering torque sensor 36 detects the steering torque, which is the input torque to the steering wheel 31 by the driver.
  • the steering torque corresponds to the reaction torque that the driver receives from the steering wheel 31.
  • the turning angle sensor 58 detects the turning angle (wheel angle) of the left and right front wheels 3LF, 3RF.
  • the tire force sensors 9L, 9R detect the self-aligning torque applied to the left and right front wheels 3LF, 3RF from the road surface.
  • a torque sensor may be provided coaxially on the pinion shaft 56 to detect the self-aligning torque.
  • the steering control device 60 controls the drive of the reaction motor 34 and the turning motor 57 based on the input from each of these sensors. In other words, the steering control device 60 controls the linkless steering device 33 and the wheel turning device 40 in conjunction with each other (steer-by-wire control) according to a pre-stored program.
  • the steering control device 60 functions as a device that executes processing to control the electric steering system 30 by executing a computer program by a processor such as one or more CPUs (Central Processing Units).
  • the computer program is a computer program for causing the processor to execute operations to be performed by the steering control device 60, which will be described later.
  • the computer program executed by the processor may be recorded on a recording medium that functions as a storage unit (memory) provided in the steering control device 60, or may be recorded on a recording medium built into the steering control device 60 or any recording medium that can be externally attached to the steering control device 60.
  • Recording media for recording computer programs may include magnetic media such as hard disks, floppy disks, and magnetic tapes; optical recording media such as CD-ROMs (Compact Disc-Read Only Memory), DVDs (Digital Versatile Discs), and Blu-ray (registered trademark); magnetic optical media such as floptical disks; memory elements such as RAMs (Random Access Memory) and ROMs (Read Only Memory); flash memories such as USB (Universal Serial Bus) memories and SSDs (Solid State Drives); and other media capable of storing programs.
  • magnetic media such as hard disks, floppy disks, and magnetic tapes
  • optical recording media such as CD-ROMs (Compact Disc-Read Only Memory), DVDs (Digital Versatile Discs), and Blu-ray (registered trademark)
  • magnetic optical media such as floptical disks
  • memory elements such as RAMs (Random Access Memory) and ROMs (Read Only Memory)
  • flash memories such as USB (Universal Serial Bus) memories and SSDs (Solid
  • FIG. 3 is a block diagram showing an example of the configuration of the steering control device 60.
  • the steering control device 60 includes a processing unit 61 and a storage unit 63.
  • the processing unit 61 is configured to include one or more processors. A part or the whole of the processing unit 61 may be configured with an updatable component such as firmware, or may be a program module executed by a command from a CPU or the like.
  • the steering control device 60 may be configured as a single device, or may be configured by connecting multiple devices so that they can communicate with each other.
  • the storage unit 63 is composed of one or more storage elements (memories), such as RAM or ROM, communicatively connected to the processing unit 61. However, the number and type of storage units 63 are not particularly limited.
  • the storage unit 63 stores computer programs executed by the processing unit 61, various parameters used in arithmetic processing, detection data, calculation results, and other data. A part of the storage unit 63 functions as a work area for the processing unit 61.
  • the steering control device 60 is communicatively connected to the driving assistance device 17, tire force sensors 9L, 9R, steering angle sensor 35, steering torque sensor 36, turning angle sensor 58, tire force sensors 9L, 9R, reaction motor 34, and turning motor 57 via a dedicated line or communication means such as CAN (Controller Area Network) or LIN (Local Inter Net).
  • CAN Controller Area Network
  • LIN Local Inter Net
  • the processing unit 61 includes a first control unit 71, a second control unit 73, and a switching control unit 75.
  • the first control unit 71, the second control unit 73, and the switching control unit 75 are functions realized by the execution of a computer program by one or more processors. Note that a portion of the first control unit 71, the second control unit 73, and the switching control unit 75 may be configured by hardware such as an analog circuit.
  • the first control unit 71 controls the steering angle based on the steering angle of the steering wheel 31 operated by the driver, and also performs a first control that applies a reaction torque to the steering wheel 31 against the operation of the steering wheel 31 in accordance with the self-aligning torque that the left and right front wheels 3LF, 3RF receive from the road surface.
  • the first control unit 71 detects the steering angle of the steering wheel 31 based on the sensor signal of the steering angle sensor 35, and sets target steering angles for the left and right front wheels 3LF, 3RF based on the actual steering angle.
  • the steering angle detected based on the sensor signal of the steering angle sensor 35 is referred to as the actual steering angle.
  • the steering angle and the steering angle can be converted into each other using a predetermined coefficient that is set in advance, and the first control unit 71 sets the target steering angle based on the actual steering angle using the coefficient.
  • the first control unit 71 also converts the target steering angle into a rotation angle of the steering motor 57, and controls the rotation angle of the steering motor 57.
  • the first control unit 71 detects the self-aligning torque that the front wheels 3LF, 3RF receive from the road surface based on the sensor signals of the tire force sensors 9L, 9R, and sets the reaction torque to be applied to the steering wheel 31 based on the self-aligning torque.
  • the self-aligning torque is a restoring force that acts to return the orientation of the front wheels 3LF, 3RF to the fore-and-aft direction of the vehicle 1 while the vehicle 1 is turning.
  • the reaction torque is a restoring force that acts to return the steering wheel 31 to a neutral position (a position where the vehicle 1 is in a straight-ahead state) in response to the self-aligning torque acting on the front wheels 3LF, 3RF.
  • the self-aligning torque and the reaction torque can be converted into each other using a predetermined coefficient that has been set in advance, and the first control unit 71 sets the reaction torque based on the self-aligning torque using the coefficient.
  • the first control unit 71 also sets a drive instruction value for the reaction motor 34 that can output the set reaction torque, and controls the drive of the reaction motor 34.
  • Figure 4 shows an aligning torque map (aligning torque information) that indicates the reaction torque F_co according to the steering angle ⁇ s of the steering wheel 31.
  • the steering angle ⁇ s is shown with the neutral position ⁇ 0 as the center, with the right turning direction ⁇ s_R as a positive value and the left turning direction ⁇ s_L as a negative value.
  • the reaction torque F_co is shown with the force pushing the steering wheel 31 in the left turning direction as a positive value and the force pushing the steering wheel 31 in the right turning direction as a negative value.
  • the relationship between the steering angle ⁇ s and the reaction torque F_co shown in the aligning torque map can also be seen as the relationship between the steering angle of the front wheels 3LF, 3RF and the self-aligning torque that the front wheels 3LF, 3RF receive from the road surface.
  • the second control unit 73 executes a second control that controls the steering angle and the turning angle based on the target steering angle by the driving assistance control of the driving assistance device 17, and applies a steering assist torque to the steering wheel 31 according to the angle difference between the target steering angle and the steering angle or the turning angle.
  • the steering angle and the turning angle are mutually convertible, and the target steering angle may be either the target value of the steering angle or the target value of the turning angle, but in this embodiment, an example will be described in which the target steering angle is the target value of the steering angle (hereinafter referred to as the "target steering angle"). Therefore, in the following description, the angle difference between the target steering angle and the steering angle indicates a value obtained by subtracting the absolute value of the target steering angle from the absolute value of the steering angle.
  • the second control unit 73 controls the steering angle of the front wheels 3LF, 3RF based on the target steering angle set by an assistance function that automatically drives the vehicle 1 in a predetermined position in the driving lane, such as lane keeping control or automatic driving control by the driving assistance device 17.
  • the second control unit 73 sets the target steering angle based on the target steering angle using a predetermined coefficient.
  • the second control unit 73 also converts the target steering angle into the rotation angle of the steering motor 57 and controls the rotation angle of the steering motor 57.
  • the second control unit 73 also controls the steering angle of the steering wheel 31 based on the target steering angle set by the driving assistance device 17. At this time, the second control unit 73 sets a steering assist torque according to the angular difference between the target steering angle and the actual steering angle.
  • the steering assist torque is an assist force that acts to make the actual steering angle follow the target steering angle.
  • the second control unit 73 sets the steering assist torque using an assist torque map (assist torque information) in which the value of the steering assist torque for the angular difference is preset.
  • the second control unit 73 sets a drive instruction value for the reaction motor 34 capable of outputting the set steering assist torque, and controls the drive of the reaction motor 34.
  • Figure 5 shows an assist torque map in which the steering assist torque F_as to be generated according to the angular difference ⁇ between the target steering angle ⁇ s_tgt and the steering angle ⁇ s is set.
  • the steering assist torque F_as indicates a force pushing in the direction of reducing the steering angle ⁇ s as a positive value and a force pushing in the direction of increasing the steering angle ⁇ s as a negative value.
  • the illustrated switching threshold ⁇ _thr is a threshold at which the steering control is switched (overridden) from the second control based on the driving assistance control to the first control based on the driver's steering.
  • the absolute value of the steering assist torque F_as gradually increases as the absolute value of the angle difference ⁇ between the steering angle ⁇ s and the target steering angle ⁇ s_tgt increases, but the steering assist torque F_as is set to zero at the switching threshold value - ⁇ _thr at which the steering control is switched from the second control to the first control.
  • the switching control unit 75 executes switching control to release the second control and switch the steering control to the first control as the angle difference between the target steering angle and the steering angle increases during execution of the second control.
  • the switching control unit 75 detects that the driver is intentionally attempting to correct the driving trajectory while the vehicle 1 is being automatically steered by the driving assistance function so as to drive along the target driving trajectory, and switches (overrides) to the first control that controls the steering angle based on the steering operation by the driver.
  • the switching control unit 75 switches the steering control from the second control to the first control when the difference ⁇ F between the steering assist torque F_as and the reaction torque F_co before and after switching the steering control from the second control to the first control is equal to or less than a predetermined torque difference threshold ⁇ F_thr for suppressing a preset torque fluctuation.
  • the predetermined torque difference threshold ⁇ F_thr is set in advance to an appropriate value that can suppress a large fluctuation in the torque applied and a sudden change in the steering angle ⁇ s when the torque applied to the steering wheel 31 is switched from the steering assist torque F_as to the reaction torque F_co as the steering control is switched from the second control to the first control.
  • the predetermined torque difference threshold ⁇ F_thr is preferably set to a value of 0.5 N ⁇ m or less, for example, or a value of 30% or less of the reaction torque F_co, and more preferably set to 0.
  • the steering control is switched from the second control to the first control when the absolute value of the steering assist torque is equal to or less than a predetermined reference value.
  • the direction of the force of the steering assist torque F_as by the second control and the direction of the force of the reaction torque F_co by the first control are opposite to each other, so that the torque fluctuation when the steering control is switched from the second control to the first control becomes large, which may cause the driver to feel uncomfortable and the behavior of the vehicle 1 to become unstable.
  • the steering assist torque F_as when the steering control is switched from the second control to the first control while the steering wheel 31 is being turned back is set to a predetermined reference value F_thr or less to suppress the torque fluctuation when the steering control is switched from the second control to the first control.
  • FIG. 6 and 7 are diagrams for explaining a reference example in which the steering assist torque F_as is set to gradually increase as the angular difference ⁇ between the target steering angle ⁇ s_tgt and the steering angle ⁇ s increases in the second control, and the steering control is switched from the second control to the first control when the angular difference ⁇ exceeds the switching threshold ⁇ _thr.
  • FIG. 6 is an explanatory diagram showing the relationship between the angular difference ⁇ and the steering assist torque F_as, and corresponds to the assist torque map according to this embodiment shown in FIG. 5.
  • FIG. 7 is an explanatory diagram of a reference example in which the steering assist torque F_as based on the target steering angle ⁇ s_tgt when the vehicle 1 is turning right is superimposed on the aligning torque map.
  • the steering assist torque F_as is set so that its absolute value gradually increases as the angle difference ⁇ increases, regardless of the magnitude relationship between the steering angle ⁇ s and the target steering angle ⁇ s_tgt, and regardless of the value of the target steering angle ⁇ s_tgt.
  • the steering control is switched from the second control to the first control.
  • the steering assist torque F_as greatly exceeds the reaction torque F_co at the steering angle ⁇ s_h
  • the torque applied to the steering wheel 31 changes greatly before and after the switching of the steering control from the second control to the first control. For this reason, the steering angle ⁇ s of the steering wheel 31 changes abruptly, which may cause the behavior of the vehicle 1 to become unstable.
  • the steering control is switched from the second control to the first control.
  • the steering assist torque F_as and the reaction torque F_co are torques in opposite directions, and the torque applied to the steering wheel 31 changes suddenly before and after the switching of the steering control from the second control to the first control. For this reason, the steering angle ⁇ s of the steering wheel 31 changes suddenly, which may cause the driver to feel uncomfortable and the behavior of the vehicle 1 to become unstable.
  • FIG. 8 is an explanatory diagram of this embodiment that shows the steering assist torque F_as based on the target steering angle ⁇ s_tgt when the vehicle 1 is turning right, superimposed on the aligning torque map.
  • the switchover of steering control from the second control to the first control is determined not based on the angle difference ⁇ between the steering angle ⁇ s and the target steering angle ⁇ s_tgt, but based on the difference between the steering assist torque F_as and the reaction torque F_co before and after the switchover of steering control from the second control to the first control.
  • the switching control unit 75 releases the second control and switches the steering control to the first control when the difference ⁇ F between the steering assist torque F_as and the reaction torque F_co before and after switching the steering control from the second control to the first control becomes equal to or less than a predetermined torque difference threshold ⁇ F_thr for suppressing a preset torque fluctuation.
  • the steering control is switched from the second control to the first control when the steering angle ⁇ s reaches the steering angle ⁇ s_l at which the angular difference ⁇ between the steering angle ⁇ s and the target steering angle ⁇ s_tgt becomes a predetermined switching threshold ⁇ _thr, based on the angular difference ⁇ between the steering angle ⁇ s and the target steering angle ⁇ s_tgt.
  • the steering assist torque F_as is set to a predetermined reference value or less.
  • the steering assist torque F_as is set to zero at the steering angle ⁇ s_l at which the steering control is switched from the second control to the first control. Therefore, an assist force is applied to make the steering angle ⁇ s follow the target steering angle ⁇ s_tgt, while reducing the discomfort felt by the driver due to the torque direction being reversed before and after switching the steering control from the second control to the first control.
  • FIG. 9 is a flowchart showing the processing operation of the steering control device 60.
  • the processing unit 61 determines whether or not the driving assistance function is operating (step S13). For example, the processing unit 61 determines that the driving assistance function is operating when a signal indicating that the driving assistance function is operating is received from the driving assistance device 17. The processing unit 61 may determine whether or not the driving assistance function is operating based on an on/off signal of an operating switch of the driving assistance function.
  • the driving assistance function is an assistance function that automatically drives the vehicle 1 in a predetermined position in the driving lane, and may be, for example, lane keeping control or automatic driving control.
  • the processing unit 61 determines that the driving assistance function is operating (S13/No)
  • the first control unit 71 executes the first control (step S15).
  • FIG. 10 is a flowchart showing the processing operation of the first control by the first control unit 71.
  • the first control unit 71 detects the actual steering angle ⁇ s_act of the steering wheel 31 based on the sensor signal of the steering angle sensor 35 (step S31).
  • the first control unit 71 sets the target turning angle ⁇ w_tgt based on the actual steering angle ⁇ s_act (step S33). For example, the first control unit 71 calculates the target turning angle ⁇ w_tgt by multiplying the actual steering angle ⁇ s_act by a predetermined coefficient set in advance.
  • the first control unit 71 drives the steering motor 57 to control the steering of the front wheels 3LF, 3RF (step S35).
  • the first control unit 71 refers to a map that defines the relationship between the steering angle and the drive command value of the steering motor 57, determines the drive command value that corresponds to the target steering angle ⁇ w_tgt, and drives the steering motor 57.
  • the first control unit 71 detects the self-aligning torque F_al that the left and right front wheels 3LF, 3RF receive from the road surface based on the sensor signals of the tire force sensors 9L, 9R (step S37). Next, the first control unit 71 multiplies the self-aligning torque F_al by a predetermined coefficient to calculate the reaction torque F_co (step S39).
  • the first control unit 71 drives the reaction motor 34 to apply a reaction torque F_co corresponding to the self-aligning torque F_al to the steering wheel 31 (step S41).
  • the first control unit 71 controls the steering angle ⁇ w of the left and right front wheels 3LF, 3RF based on the actual steering angle ⁇ s_act of the steering wheel 31 as a result of the driver's operation.
  • the first control unit 71 imparts to the steering wheel 31 a reaction torque F_co that corresponds to the self-aligning torque F_al that the left and right front wheels 3LF, 3RF receive from the road surface, causing the driver to feel a reaction force that corresponds to the self-aligning torque F_al.
  • step S13 if the processing unit 61 determines that the driving assistance function is operating (S13/Yes), the second control unit 73 executes steering control using the second control (step S17).
  • FIG. 11 is a flowchart showing the processing operation of the second control by the second control unit 73.
  • the second control unit 73 acquires information on the target steering angle ⁇ s_tgt transmitted from the driving support device 17 (step S51).
  • the second control unit 73 detects the actual steering angle ⁇ s_act of the steering wheel 31 based on the sensor signal of the steering angle sensor 35 (step S53).
  • the second control unit 73 calculates the angle difference ⁇ by subtracting the target steering angle ⁇ s_tgt from the actual steering angle ⁇ s_act (step S55). Here, it is determined whether the actual steering angle ⁇ s_act is turned too far or too far from the target steering angle ⁇ s_tgt.
  • the second control unit 73 sets the steering assist torque F_as based on the calculated angular difference ⁇ (step S57). For example, the second control unit 73 sets the steering assist torque F_as according to the angular difference ⁇ based on a preset assist torque map (see FIG. 5). Next, the second control unit 73 drives the reaction motor 34 to apply the steering assist torque F_as to the steering wheel 31 (step S59).
  • the second control unit 73 sets the target steering angle ⁇ w_tgt based on the actual steering angle ⁇ s_act (step S61), similar to step S33 described above.
  • the second control unit 73 drives the steering motor 57, similar to step S35 described above, to control the steering of the front wheels 3LF, 3RF (step S63).
  • the second control unit 73 sets the steering assist torque F_as based on the angle difference ⁇ between the target steering angle ⁇ s_tgt set by the driving support device 17 and the actual steering angle ⁇ s, and applies the steering assist torque F_as to the steering wheel 31 to make the actual steering angle ⁇ s follow the target steering angle ⁇ s_tgt. Then, the second control unit 73 controls the steering angle ⁇ w of the left and right front wheels 3LF, 3RF based on the actual steering angle ⁇ s_act.
  • the steering of the vehicle 1 is basically controlled according to the target steering angle ⁇ s_tgt set by the driving support device 17, but when the driver intervenes in the operation of the steering wheel 31, the vehicle 1 is steered to reflect the driver's intention.
  • the switching control unit 75 executes switching control (step S19).
  • FIG. 12 is a flowchart showing the processing operation of the switching control by the switching control unit 75.
  • the switching control unit 75 determines whether or not the actual steering angle ⁇ s_act detected based on the sensor signal of the steering angle sensor 35 is larger than the target steering angle ⁇ s_tgt set by the driving support device 17 (step S71).
  • the switching control unit 75 determines whether the actual steering angle ⁇ s_act is greater than the target steering angle ⁇ s_tgt (S71/No). If the switching control unit 75 does not determine that the angle difference ⁇ obtained by subtracting the actual steering angle ⁇ s_act from the target steering angle ⁇ s_tgt exceeds a predetermined switching threshold ⁇ _tgt (step S81). If the switching control unit 75 does not determine that the angle difference ⁇ exceeds the predetermined switching threshold ⁇ _tgt (S81/No), it ends the switching control as is and continues the second control.
  • the switching control unit 75 determines that the angle difference ⁇ exceeds the predetermined switching threshold ⁇ _tgt (S81/Yes), it cancels the second control and switches the steering control to the first control (step S79). In other words, it is determined that the driver is intentionally attempting to correct the driving trajectory in a direction to turn the steering wheel 31 back relative to the target steering angle ⁇ s_tgt, so the switching control unit 75 overrides the steering control based on the driving assistance function to steering control based on the driver's steering operation.
  • the steering assist torque F_as is set to zero or a very small value that is less than a predetermined reference value. This makes it possible to reduce the discomfort felt by the driver due to the torque applied to the steering wheel 31 being in the opposite direction before and after the steering control is switched from the second control to the first control.
  • step S71 above the switching control unit 75 determines that the actual steering angle ⁇ s_act is greater than the target steering angle ⁇ s_tgt (S71/Yes), it detects the self-aligning torque F_al that the left and right front wheels 3LF, 3RF receive from the road surface based on the sensor signals of the tire force sensors 9L, 9R, as in step S37 above (step S73). Next, the switching control unit 75 multiplies the self-aligning torque F_al by a predetermined coefficient to calculate the reaction torque F_co, as in step S39 above (step S75).
  • the switching control unit 75 determines whether the difference ⁇ F between the calculated reaction torque F_co and the steering assist torque F_as applied to the steering wheel 31 is equal to or less than a predetermined torque difference threshold ⁇ F_thr that has been set in advance (step S75). For example, the switching control unit 75 determines whether the difference ⁇ F between the reaction torque F_co and the steering assist torque F_as is zero.
  • the switching control unit 75 does not determine that the difference ⁇ F between the reaction torque F_co and the steering assist torque F_as is equal to or less than the predetermined torque difference threshold ⁇ F_thr (S75/No), it ends the switching control and continues the second control.
  • the switching control unit 75 determines that the difference ⁇ F between the reaction torque F_co and the steering assist torque F_as is equal to or less than the predetermined torque difference threshold ⁇ F_thr (S75/No), it cancels the second control and switches the steering control to the first control (step S79). In other words, it is determined that the driver is intentionally attempting to correct the driving trajectory in a direction to turn the steering wheel 31 more with respect to the target steering angle ⁇ s_tgt, so the switching control unit 75 overrides the steering control based on the driving support function to steering control based on the driver's steering operation.
  • the steering control is switched from the second control to the first control in a state where the difference between the steering assist torque F_as and the reaction torque F_co applied to the steering wheel 31 before and after the steering control is switched from the second control to the first control is zero or extremely small. Therefore, a sudden change in the torque applied to the steering wheel 31 due to the switching of the steering control from the second control to the first control is suppressed, and a sudden change in the steering angle of the steering wheel 31 can be suppressed.
  • the processing unit 61 determines whether or not the activation of the steering system 10 has been stopped (step S21). If the processing unit 61 does not determine that the activation of the steering system 10 has been stopped (S21/No), the processing unit 61 returns to step S13 and executes the processing of each step described above. On the other hand, if the processing unit 61 determines that the activation of the steering system 10 has been stopped (S21/Yes), the processing unit 61 ends the steering control.
  • the control device of the steering system switches from the second control to the first control in a state where the difference ⁇ F between the steering assist torque F_as and the reaction torque F_co before and after switching the steering control from the second control to the first control is equal to or less than a predetermined torque difference threshold ⁇ F_thr set in advance.
  • the control device of the steering system may also switch from the second control to the first control when the difference ⁇ F between the steering assist torque F_as and the reaction torque F_co before and after switching the steering control from the second control to the first control is zero.
  • the fluctuation in the torque applied to the steering wheel 31 due to switching the steering control from the second control to the first control becomes extremely small, and the change in the steering angle of the steering wheel 31 can be further suppressed.
  • the steering assist torque F_as applied to the steering wheel 31 while the second control is being executed is set based on the angle difference ⁇ obtained by subtracting the target steering angle ⁇ s_tgt from the actual steering angle ⁇ s_act, regardless of the value of the target steering angle ⁇ s_tgt.
  • the steering assist torque F_as may be changed depending on the frictional state of the road surface.
  • the self-aligning torque F_al that the front wheels 3LF, 3RF receive from the road surface changes depending on the friction coefficient of the road surface. For this reason, if the steering assist torque F_as is not changed according to the friction coefficient of the road surface, in a situation where the steering control is switched from the second control to the first control when the actual steering angle ⁇ s_act is larger than the target steering angle ⁇ s_tgt, the steering angle ⁇ s at which the steering control is switched may differ significantly depending on the friction coefficient of the road surface, even if the target steering angle ⁇ s_tgt is the same.
  • FIG. 13 is an explanatory diagram showing an example in which the friction coefficient of the road surface is smaller than the example shown in FIG. 8.
  • the reaction torque F_co set according to the self-aligning torque is smaller than the reaction torque F_co' when the friction coefficient of the road surface is relatively large.
  • the steering angle ⁇ s_c at which the difference ⁇ F between the steering assist torque F_as and the reaction torque F_co is equal to or smaller than a predetermined torque difference threshold ⁇ F_thr is smaller than the steering angle ⁇ s_c' at which the difference ⁇ F between the steering assist torque F_as and the reaction torque F_co' is equal to or smaller than the predetermined torque difference threshold ⁇ F_thr.
  • the second control unit 73 may correct the steering assist torque F_as generated when at least the actual steering angle ⁇ s_act is greater than the target steering angle ⁇ s_tgt so that the smaller the friction coefficient of the road surface, the smaller the value. This allows the second control unit 73 to prevent a large difference in the timing at which the steering control is switched from the second control to the first control, at least when the actual steering angle ⁇ s_act is greater than the target steering angle ⁇ s_tgt.
  • the second control unit 73 corrects the steering assist torque F_as calculated based on an assist torque map in which a reference steering assist torque F_as is set, with a correction coefficient according to the friction coefficient of the road surface.
  • multiple assist torque maps set according to the friction coefficient of the road surface may be stored in advance in the storage unit 63, and the second control unit 73 may change the assist torque map to be used according to the friction coefficient of the road surface and set the steering assist torque F_as.
  • the target steering angle was the target value of the steering angle
  • the target steering angle may also be the target value of the turning angle.
  • the same effect can be obtained by implementing the angle difference between the actual steering angle and the target steering angle in the above embodiment as the angle difference between the actual turning angle and the target turning angle.
  • the technology disclosed herein can also be realized as a vehicle equipped with the steering control device described in the above embodiment, a steering control method using the steering control device, a computer program that causes a computer to function as the above steering control device, and a non-transitory tangible recording medium on which the computer program is recorded.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Steering Control In Accordance With Driving Conditions (AREA)

Abstract

L'invention concerne un dispositif de commande de système de direction de type à commande électrique qui exécute : une première commande dans laquelle un angle de rotation est commandé sur la base d'un angle de direction d'un volant de direction manipulé par un conducteur et dans lequel un couple de réaction à la manipulation du volant de direction est communiqué au volant de direction en fonction d'un couple d'auto-alignement reçu par une roue à partir de la surface de route ; une deuxième commande dans laquelle l'angle de direction et l'angle de rotation sont commandés sur la base d'un angle de direction cible dérivé d'une commande d'aide à la conduite prescrite et un couple d'assistance de direction correspondant à la différence d'angle entre l'angle de direction cible et l'angle de direction ou l'angle de rotation est communiqué au volant ; et une commande de commutation dans laquelle, pendant l'exécution de la deuxième commande, la deuxième commande est libérée et commutée vers la première commande à mesure que la différence d'angle augmente. Si la différence d'angle augmente dans un état dans lequel l'angle de direction ou l'angle de rotation est supérieur à l'angle de direction cible, la commande est commutée de la deuxième commande à la première commande dans un état dans lequel la différence entre le couple d'assistance de direction et le couple de réaction avant et après la commutation de la deuxième commande à la première commande n'est pas supérieure à une valeur de seuil de différence de couple prescrite.
PCT/JP2023/034870 2023-09-26 2023-09-26 Dispositif de commande de système de direction et procédé de commande Pending WO2025069169A1 (fr)

Priority Applications (1)

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PCT/JP2023/034870 WO2025069169A1 (fr) 2023-09-26 2023-09-26 Dispositif de commande de système de direction et procédé de commande

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/JP2023/034870 WO2025069169A1 (fr) 2023-09-26 2023-09-26 Dispositif de commande de système de direction et procédé de commande

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2016107750A (ja) * 2014-12-04 2016-06-20 日産自動車株式会社 車線維持支援装置及び車線維持支援方法
WO2019225289A1 (fr) * 2018-05-21 2019-11-28 株式会社ジェイテクト Dispositif de commande de moteur
JP2022111970A (ja) * 2021-01-20 2022-08-01 トヨタ自動車株式会社 操舵システム

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2016107750A (ja) * 2014-12-04 2016-06-20 日産自動車株式会社 車線維持支援装置及び車線維持支援方法
WO2019225289A1 (fr) * 2018-05-21 2019-11-28 株式会社ジェイテクト Dispositif de commande de moteur
JP2022111970A (ja) * 2021-01-20 2022-08-01 トヨタ自動車株式会社 操舵システム

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