STEERING DEVICE CONTROL DEVICE, STEERING DEVICE CONTROL METHOD, AND STEERING SYSTEM

Abstract

The device for controlling a steering device, method for controlling a steering device, and steering system according to the present invention are applied to a vehicle comprising a steering device configured to be capable of independently controlling the steering angles of vehicle wheels with respect to the amount of operation of a steering operation input member. This invention involves comparing a target yaw rate based on a physical quantity related to the traveling state of the vehicle and the amount of operation of the steering operation input member, and an actual yaw rate based on a physical quantity related to the traveling state of the vehicle, and controlling a steering actuator in a direction counteracting the yaw rate of the vehicle so that the actual yaw rate approaches the target yaw rate. It is thereby possible to realize vehicle behavior that matches the intention of the driver.

Description

[Technical field]

[0001] The present invention relates to a steering device control device, a steering device control method, and a steering system. [Background technology]

[0002] The vehicle steering control device of Patent Document 1 estimates the difference between the braking forces applied to the left and right wheels, calculates a braking force difference control amount corresponding to the braking force difference in a direction to cancel out the yaw moment caused by the braking force difference, and controls the output angle (steering amount) by adding the braking force difference control amount when a yaw moment caused by the braking force difference occurs. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-112285 A Summary of the Invention [Problem to be solved by the invention]

[0004] For example, when a vehicle is traveling on a μ-split road, which is a road surface with different friction coefficients for the right and left wheels, if the driver operates the braking device to apply braking force, the difference in braking force between the left and right wheels may cause the vehicle to turn toward the side with the higher friction coefficient. Such vehicle turning results in a behavior different from that of the driver's will, which may reduce the driving stability and cause the driver to feel uncomfortable.

[0005] The present invention has been made in consideration of the conventional situation, and its purpose is to provide a steering device control device, a steering device control method, and a steering system that can realize vehicle behavior that matches the driver's intentions. [Means for solving the problem]

[0006] According to one aspect of the present invention, a physical quantity related to a vehicle running state and In a steer-by-wire steering device A target yaw rate based on an operation amount of a steering operation input member is compared with an actual yaw rate based on a physical amount related to a running state of the vehicle. and when a predetermined intervention condition including the yaw rate deviation (γd) is satisfied in the vehicle behavior control, the yaw rate deviation (γd) is set as a yaw rate deviation (γD) to be used in the vehicle behavior control; The direction in which the vehicle's yaw rate is countered so that the actual yaw rate approaches the target yaw rate. The control signal is output to a steering actuator of a steer-by-wire type steering device. Effect of the Invention

[0007] According to the present invention, it is possible to realize a vehicle behavior that matches the driver's intention. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a configuration diagram showing one embodiment of a steering system for a vehicle. [Diagram 2] 5 is a flowchart showing a process for calculating a yaw rate deviation. [Diagram 3] 5 is a flowchart showing a process for calculating a target steering angle. [Figure 4] 5 is a flowchart showing a process for calculating a yaw rate deviation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a steering device control device, a steering device control method, and a steering system according to the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram showing one embodiment of a steering system 200 mounted on a vehicle 100. As shown in FIG. The vehicle 100 is a four-wheeled vehicle having four wheels 101-104.

[0010] The steering system 200 includes a steering device 300 and a control device 400 for controlling an actuator of the steering device 300 . The steering device 300 has a steering wheel 301 which is a steering operation member operated by the driver, a reaction force actuator 302 which applies a reaction torque to the steering wheel 301, and a steering device 305 which can change the steering angle σ (in other words, the tire angle) of the front wheels 101, 102 which are the steered wheels of the vehicle 100.

[0011] The steering device 305 includes a steering actuator 304 that applies a steering torque (in other words, a steering force) to the front wheels 101, 102 via a steering member 303. The steering device 300 uses, for example, electric motors as the reaction force actuator 302 and the steering actuator 304 .

[0012] In the steering device 300, the steering wheel 301 and the front wheels 101 and 102 which are steered wheels, that is, the steering device 305, are mechanically separated. That is, the steering device 300 is a steer-by-wire type steering device configured to be able to independently control the steering angles of the front wheels 101, 102 in response to the operation angle (in other words, the operation amount) of the steering wheel 301.

[0013] The control device 400 is an electronic control device equipped with an MCU (Micro Controller Unit) 401 . When the steering actuator 304 is an electric motor, the control device 400 can include, in addition to the MCU 401, a pre-driver, an inverter, and the like for controlling the supply of electricity to the electric motor. In addition to the control device 400, the system may include a drive circuit including a pre-driver, an inverter, and the like. The MCU 401 can also be referred to as a microcomputer, a processor, a processing device, an arithmetic device, or the like.

[0014] The MCU 401 of the control device 400 acquires information relating to the state of the vehicle 100 and information relating to the state of the steering device 300 . Then, based on the acquired state information, the MCU 401 calculates a control signal CS1 for the reaction force actuator 302 and a control signal CS2 for the steering actuator 304, and outputs the calculated control signals CS1, CS2 to the reaction force actuator 302 and the steering actuator 304, thereby controlling the reaction force torque applied to the steering wheel 301 and the steering torque (i.e., the steering angle σ of the front wheels 101, 102).

[0015] The vehicle 100 is equipped with sensors that detect the running state of the vehicle 100, such as wheel speed sensors 403-406 that detect the wheel speeds of the wheels 101-104, a yaw rate sensor 407 that detects the yaw rate γ of the vehicle 100, and an acceleration sensor 408 that detects the longitudinal acceleration and lateral acceleration of the vehicle 100. The steering device 300 also includes, as sensors for detecting the operating state of the steering device 300, an operation angle sensor 411 for detecting an operation angle θ of the steering wheel 301, and a steering angle sensor 412 for detecting a steering angle σ of the front wheels 101, 102. When the steering device 305 changes the steering angle σ of the front wheels 101, 102 using a rack-and-pinion mechanism, the steering angle sensor 412 can detect the rotation angle of the pinion shaft as a physical quantity equivalent to the steering angle σ.

[0016] The operation angle sensor 411 detects the neutral position of the steering wheel 301 as 0 deg. For example, when the steering wheel 301 is operated to the left from the neutral position, the operating angle sensor 411 detects the operating angle θ as a positive angle, and when the steering wheel 301 is operated to the right from the neutral position, the operating angle sensor 411 detects the operating angle θ as a negative angle.

[0017] Similarly, the steering angle sensor 412 detects the neutral position of the front wheels 101, 102 as 0 deg. The steering angle sensor 412 detects the steering angle σ as a positive angle when the front wheels 101, 102 are steered to the left from the neutral position, and detects the steering angle σ as a negative angle when the front wheels 101, 102 are steered to the right from the neutral position.

[0018] The neutral position of the front wheels 101, 102 is a position in which the front wheels 101, 102 are not steered to the left or right and the vehicle 100 moves straight ahead. The neutral position of the steering wheel 301 is a position in which the steering wheel 301 is not operated to the left or right and the front wheels 101, 102 are in a neutral position. For example, the yaw rate sensor 407 detects the rate of change as a positive value when yaw is occurring in the leftward direction, and detects the rate of change as a negative value when yaw is occurring in the rightward direction.

[0019] The vehicle 100 also includes a braking device 450 that generates a braking force on each of the wheels 101-104. Brake device 450 is a hydraulic brake device having a hydraulic pressure generating device 451 including a master cylinder or the like, and wheel cylinders 101A-104A provided on wheels 101-104, respectively.

[0020] In this braking system 450, when the driver depresses a brake pedal (not shown), the hydraulic pressure generating device 451 sends out brake hydraulic pressure to the wheel cylinders 101A-104A. The wheel cylinders 101A-104A displace brake shoes (not shown) in response to brake fluid pressure to generate braking forces on the wheels 101-104, respectively. It should be noted that the braking device 450 is not limited to a hydraulic type.

[0021] Here, the MCU 401 acquires information such as the operation angle θ of the steering wheel 301, and calculates a target steering angle σtg of the front wheels 101, 102 based on the acquired information. For example, the MCU 401 multiplies the detected value of the operation angle θ by a steering gear ratio to obtain the target steering angle σtg.

[0022] Then, the MCU 401 calculates a control signal CS2 so that the actual steering angle σ detected by the steering angle sensor 412 approaches the target steering angle σtg, and outputs the calculated control signal CS2 to the steering actuator 304. In other words, the MCU 401 constitutes a control unit that outputs a control signal CS2 to the steering actuator 304 based on a physical quantity related to the operation angle θ of the steering wheel 301.

[0023] Furthermore, the MCU 401 has a function of correcting the steering angle σ of the front wheels 101, 102 from the steering angle σ corresponding to the operation angle θ of the steering wheel 301 in order to suppress vehicle behavior in the yaw direction that is different from the driver's intention. That is, when the behavior of the vehicle 100 in the yaw direction corresponds to the driver's intention, the MCU 401 controls the steering angle σ to correspond to the operation angle θ of the steering wheel 301. On the other hand, when the behavior of the vehicle 100 in the yaw direction deviates from the driver's intention, the MCU 401 corrects the steering angle σ from the steering angle σ corresponding to the operation angle θ of the steering wheel 301 in order to suppress such behavior.

[0024] "First embodiment" The steering angle control (hereinafter also referred to as vehicle behavior control) for suppressing vehicle behavior in the yaw direction that is different from the driver's intention will be described in detail below. The first embodiment is a vehicle behavior control assuming braking on a μ-split road surface.

[0025] In vehicle behavior control, the MCU 401 determines a target yaw rate γtg, which is the yaw rate γ intended by the driver, based on a physical quantity related to the running state of the vehicle 100 and the operation angle θ of the steering wheel 301. Further, the MCU 401 acquires information on the actual yaw rate γa that is actually occurring in the vehicle 100 based on a physical quantity related to the running state of the vehicle 100. The MCU 401 compares the target yaw rate γtg with the actual yaw rate γa, and when a deviation occurs between the target yaw rate γtg and the actual yaw rate γa, that is, when the behavior of the vehicle 100 in the yaw direction becomes different from the driver's intention, the MCU 401 controls the steering actuator 304 in a direction that cancels the yaw rate γ of the vehicle 100 so that the actual yaw rate γa approaches the target yaw rate γtg.

[0026] For example, when the driver operates the braking device 450 while the vehicle 100 is traveling straight on a μ-split road, a difference in braking force between the left and right sides causes the vehicle 100 to turn toward the side with the higher friction coefficient, resulting in a deviation between the target yaw rate γtg and the actual yaw rate γa. At this time, the MCU 401 corrects the steering angle σ in a direction that reduces the deviation between the target yaw rate γtg and the actual yaw rate γa, thereby preventing the vehicle 100 from turning against the driver's will due to the difference in braking force between the left and right. Therefore, even if the vehicle 100 is braked while traveling on a μ-split road, a vehicle behavior (yaw behavior) that matches the driver's intention, in other words, the operating angle θ of the steering wheel 301, can be achieved, and a decrease in driving stability can be suppressed.

[0027] The flowcharts in FIG. 2 and FIG. 3 show the steering control process executed by the MCU 401 to realize vehicle behavior that matches the driver's intention. The flowchart in FIG. 2 shows an example of a process for acquiring a yaw rate deviation γd, which is the deviation between a target yaw rate γtg and an actual yaw rate γa.

[0028] In step S501, the MCU 401 acquires a physical quantity related to a target yaw rate γtg, which is the yaw rate γ intended by the driver, based on information related to the operation angle θ of the steering wheel 301 and physical quantities related to the running state of the vehicle 100. The MCU 401 can employ various known methods to obtain the target yaw rate γtg, which is the yaw rate γ intended by the driver.

[0029] For example, the MCU 401 calculates a target yaw rate γtg according to Equation 1 based on information on the target steering angle σ (target steering angle σ = steering gear ratio × steering angle θ) calculated from the steering angle θ of the steering wheel 301 and information on the vehicle speed V of the vehicle 100 calculated from the output signals of the wheel speed sensors 403-406.

number

[0030] Next, in step S502, the MCU 401 acquires a physical quantity related to the actual yaw rate γa based on a physical quantity related to the running state of the vehicle 100. The MCU 401 can obtain a physical quantity related to the actual yaw rate γa based on the signal output by the yaw rate sensor 407 . Further, the MCU 401 can obtain a physical quantity related to the actual yaw rate γa from a physical quantity related to the lateral acceleration (centripetal acceleration) detected by the acceleration sensor 408 and a physical quantity related to the vehicle speed V.

[0031] In the next step S503, the MCU 401 compares the target yaw rate γtg with the actual yaw rate γa to obtain information on the yaw rate deviation γd (yaw rate deviation γd=actual yaw rate γa-target yaw rate γtg). In the next step S504, the MCU 401 determines whether or not a condition for intervening in vehicle behavior control for controlling the steering actuator 304 in a direction to cancel the yaw rate γ of the vehicle 100 is satisfied. If the intervention condition is met, the MCU 401 proceeds to step S505, and if the intervention condition is not met, the MCU 401 proceeds to step S506.

[0032] Here, if the first to fourth conditions shown below are all met, the MCU 401 determines that the condition for intervening in the vehicle behavior control is met and proceeds to step S505, but if at least one of the four conditions is not met, it determines that the condition for intervening in the vehicle behavior control is not met and proceeds to step S506. First condition: Yaw rate deviation γd is equal to or greater than a specified value (specified value > 0). Second condition: Braking state Third condition: Vehicle speed V is equal to or greater than a specified speed (specified speed > 0). Condition 4: Steering system is normal

[0033] The first condition that the yaw rate deviation γd is equal to or greater than a predetermined value means, in detail, that the absolute value of the actual yaw rate γa is greater than the absolute value of the target yaw rate γtg and the difference therebetween is equal to or greater than a predetermined value. The braking state of the second condition is a state in which the braking device 450 generates a braking force. The predetermined speed in the third condition is, for example, a vehicle speed of about 2 km / h to 10 km / h at which the vehicle 100 comes to a stop, in other words, the vehicle speed immediately before the vehicle 100 comes to a stop. Furthermore, the abnormal state of the steering device 305 in which the fourth condition is not satisfied includes abnormality information acquired via the in-vehicle network, such as an abnormality in the yaw rate signal.

[0034] Of the above four conditions, the first and second conditions are for determining that a difference in braking force occurs between the left and right sides due to braking on a μ-split road surface, which causes the vehicle 100 to turn. In other words, the MCU 401 determines that the difference between the target yaw rate γtg and the actual yaw rate γa is large based on the first condition, and determines that the cause of the first condition being met is the difference in braking force between the left and right wheels based on the second condition.

[0035] Then, if the difference between the target yaw rate γtg and the actual yaw rate γa converges within a predetermined range, the MCU 401 determines that the intervention condition (more specifically, the first condition) is not satisfied, and controls the steering angle σ to a target value calculated from the operating angle θ of the steering wheel 301, as will be described in detail later. Furthermore, when braking by the braking device 450 ends, the MCU 401 determines that the intervention condition (more specifically, the second condition) is not satisfied, and controls the steering angle σ to a target value calculated from the operating angle θ of the steering wheel 301, as will be described in detail later. Therefore, after the yaw unintended by the driver has converged, the steering angle is returned to a steering angle σ that corresponds to the operation angle θ of the steering wheel 301, thereby suppressing any discomfort felt by the driver.

[0036] The third condition is to determine whether the vehicle speed V is at a level at which the MCU 401 needs to intervene in the control. That is, the vehicle speed range below the predetermined speed (below a predetermined value) in the third condition is a vehicle speed range in which the driver can appropriately perform a steering operation to suppress turning of the vehicle 100 caused by the left and right difference in braking force.

[0037] Therefore, when the vehicle speed V is less than the predetermined speed, the MCU 401 determines that the intervention condition is not satisfied, and stops outputting to the steering actuator 304 a control signal for bringing the actual yaw rate γa closer to the target yaw rate γtg. In other words, when the vehicle 100 stops, the MCU 401 stops the vehicle behavior control, and controls the steering angle σ to a target value determined from the operation angle θ of the steering wheel 301.

[0038] When the vehicle 100 is restarted after coming to a stop, if the steering angle σ does not correspond to the operation angle θ of the steering wheel 301, the driving stability will be impaired and the driver will feel uncomfortable. In response to this, when the vehicle 100 stops, the MCU 401 sets the steering angle σ according to the operating angle θ of the steering wheel 301, thereby preventing a decrease in the steering stability when the vehicle 100 restarts and also preventing the driver from feeling uncomfortable.

[0039] The fourth condition is for determining whether the MCU 401 is in a state in which it can normally carry out intervention control. When an abnormality occurs in the steering device 305, the MCU 401 determines that the intervention condition is not satisfied, and stops outputting to the steering actuator 304 a control signal for bringing the actual yaw rate γa closer to the target yaw rate γtg. By setting the fourth condition as the execution condition for the intervention control, the MCU 401 can prevent unexpected steering control from being executed due to execution of the intervention control when the steering device 305 has an abnormality.

[0040] When the MCU 401 determines that the intervention condition is met and proceeds to step S505, it sets the yaw rate deviation γd calculated in step S503 as the yaw rate deviation γD to be used for vehicle behavior control (yaw rate deviation γD=yaw rate deviation γd). In this case, as will be described in detail later, the MCU 401 performs vehicle behavior control by outputting a control signal to the steering actuator 304 in a direction that cancels the yaw rate γ of the vehicle 100 so that the actual yaw rate γa approaches the target yaw rate γtg.

[0041] In other words, the MCU 401 performs vehicle behavior control to correct the steering angle σ in the direction opposite to the yaw direction of the vehicle 100 so that the yaw rate deviation γ D approaches zero. By carrying out such vehicle behavior control, the MCU 401 can prevent the vehicle 100 from turning against the driver's will even if a difference in braking force occurs between the left and right sides due to braking on a μ-split road surface.

[0042] On the other hand, when the MCU 401 determines that the intervention condition is not satisfied and proceeds to step S506, it sets the yaw rate deviation γD used in the vehicle behavior control to zero, that is, it assumes that the actual yaw rate γa coincides with the target yaw rate γtg in terms of control, thereby stopping intervention in the vehicle behavior control (in other words, it cancels the vehicle behavior control). In this case, as will be described in detail later, the MCU 401 performs normal control to control the steering angle σ according to the operating angle θ of the steering wheel 301, thereby setting the steering angle σ to a value that matches the operating angle θ of the steering wheel 301, thereby preventing the driver from feeling uncomfortable.

[0043] Incidentally, the braking state of the second condition in step S504 is a state in which the braking force is generated by the braking device 450, as described above. Here, the MCU 401 can determine whether the second condition is met based on information about the forward / rearward acceleration detected by the acceleration sensor 408.

[0044] In detail, when the acceleration sensor 408 detects a negative acceleration (in other words, a decelerating acceleration) that is an acceleration opposite to the direction of travel of the vehicle 100, and the absolute value of the negative acceleration is greater than or equal to a predetermined acceleration, the MCU 401 can determine that the second condition is satisfied, i.e., that the vehicle 100 is in a braking state. In other words, when acceleration is expressed as positive or negative, MCU 401 can determine that a braking state is occurring if the actual acceleration is below a predetermined negative acceleration, and can determine that a braking state is not occurring if the actual acceleration is equal to or greater than the predetermined negative acceleration. In this case, when the actual acceleration is equal to or greater than a predetermined negative acceleration, the MCU 401 determines that the intervention condition is not satisfied and stops outputting to the steering actuator 304 a control signal for bringing the actual yaw rate γa closer to the target yaw rate γtg.

[0045] In addition, the MCU 401 acquires an on / off signal of a brake switch that is on when the braking device 450 of the vehicle 100 is in operation and off when the braking device 450 is not in operation, and can determine that the second condition is met when the brake switch is on, i.e., the vehicle 100 is in a braking state. Furthermore, the MCU 401 acquires physical quantities related to the braking force, such as the brake fluid pressure in the braking device 450, and when the brake fluid pressure is equal to or greater than a predetermined value, it can determine that the second condition is satisfied, i.e., that the vehicle 100 is in a braking state.

[0046] The flowchart in FIG. 3 shows one embodiment of vehicle behavior control, which is control of the steering actuator 304 based on the yaw rate deviation γD. In the vehicle behavior control shown in the flowchart of FIG. 3, the MCU 401 determines a feedback operation amount FB for correcting a target steering angle σtg corresponding to an operation angle θ of the steering wheel 301, based on a yaw rate deviation γD.

[0047] Here, the feedback manipulated variable FB includes a proportional component P (in other words, a proportional manipulated variable) obtained by proportional action, and an integral component I (in other words, an integral manipulated variable) obtained by integral action. Then, the MCU 401 corrects the target steering angle σtg corresponding to the operation angle θ of the steering wheel 301 with the feedback operation amount FB, and sets the result as the final target steering angle σtgf, and controls the steering actuator 304 so that the actual steering angle σ approaches the target steering angle σtgf. In other words, the MCU 401 controls the steering actuator 304 in a direction to cancel the yaw rate γ of the vehicle 100 so that the actual yaw rate γa approaches the target yaw rate γtg (in other words, so that the yaw rate deviation γD approaches zero) through correction control of the target steering angle σtg based on the yaw rate deviation γD.

[0048] The processing at each step shown in the flowchart of FIG. 3 will be described in detail below. In step S601, the MCU 401 obtains the yaw rate deviation γ D obtained according to the process shown in the flowchart of FIG. Then, in step S602, the MCU 401 obtains a proportional component P based on a proportional operation that changes the amount of operation of the steering angle σ in proportion to the magnitude of the yaw rate deviation γD.

[0049] In addition, in parallel with the process of calculating the proportional component P in step S602, the MCU 401 performs a process of calculating the integral component I in steps S603 to S605. In step S603, the MCU 401 determines whether the vehicle 100 is in a braking state based on the detected longitudinal acceleration value, the on / off signal of the brake switch, the brake fluid pressure signal, and the like.

[0050] If the vehicle 100 is in a braking state, the MCU 401 proceeds to step S604. In step S604, the MCU 401 obtains an integral component I based on an integral operation that makes the rate of change in the operation amount of the steering angle σ proportional to the yaw rate deviation γD.

[0051] On the other hand, if the vehicle 100 is not in a braking state, the MCU 401 proceeds to step S605 and sets the integral component I to zero. For example, the yaw moment generated in vehicle 100 due to braking on a μ-split road surface tends to zero when braking ends, so MCU 401 sets integral component I to zero when braking ends and stops the integral operation after braking ends.

[0052] In step S606, the MCU 401 adds the proportional component P and the integral component I to obtain the feedback manipulated variable FB. Next, in step S607, the MCU 401 executes a process of gradually decreasing the feedback operation amount FB in response to a decrease in the vehicle speed V.

[0053] For example, the MCU 401 reduces the coefficient K for gradually decreasing the feedback control input FB from 100% as the vehicle speed V decreases from a predetermined speed, and sets the coefficient K to 0% when the vehicle speed V is 0 km / h. Then, the MCU 401 multiplies the feedback manipulated variable FB calculated in step S606 by the coefficient K, and sets the result as the feedback manipulated variable FBd after the gradual reduction process.

[0054] Next, in step S608, the MCU 401 adds the feedback operation amount FBb to the target steering angle σtg corresponding to the operation angle θ of the steering wheel 301 to obtain a final target steering angle σtgf. Then, the MCU 401 adjusts the control signal to be output to the steering actuator 304 so that the actual steering angle σ detected by the steering angle sensor 412 approaches the target steering angle σtgf.

[0055] The MCU 401 performs vehicle behavior control, which is control of the steering angle σ based on the above-mentioned yaw rate deviation γD, and thereby can prevent the vehicle 100 from turning against the driver's will due to, for example, a difference in braking force between the left and right sides on a μ-split road surface, and can realize vehicle behavior that matches the driver's will. In addition, when the vehicle 100 stops after intervention of the vehicle behavior control, the MCU 401 can maintain the steering angle σ corresponding to the operating angle θ of the steering wheel 301, thereby preventing a decrease in handling stability when the vehicle 100 restarts and preventing the driver from feeling uncomfortable.

[0056] Here, the MCU 401 can make the drive speed of the steering actuator 304 (in other words, the steering speed of the front wheels 101, 102) when returning the steering angle σ corresponding to the operating angle θ of the steering wheel 301 slower when the vehicle 100 is stopped than when the vehicle 100 is moving. When the vehicle 100 is stopped, the vehicle noise is smaller than when the vehicle is moving (in other words, while moving), so the operating sound of the steering actuator 304 is easily transmitted to the driver, and the operating sound of the steering actuator 304 for returning the steering angle σ corresponding to the operating angle θ of the steering wheel 301 may give the driver a sense of discomfort. Therefore, when the vehicle 100 is stopped, the MCU 401 slows down the drive speed of the steering actuator 304 when returning the steering angle σ corresponding to the operating angle θ of the steering wheel 301 compared to when the vehicle 100 is moving, thereby reducing the operating noise of the steering actuator 304 and preventing the operating noise of the steering actuator 304 from being transmitted to the driver.

[0057] In other words, the MCU 401 makes the drive speed of the steering actuator 304 when returning the steering angle σ corresponding to the operation angle θ of the steering wheel 301 faster when the vehicle 100 is in a traveling state than when the vehicle is stopped. As a result, when the yaw behavior associated with braking converges and vehicle behavior control is stopped while the vehicle 100 is running, the steering angle quickly returns to the steering angle σ corresponding to the operating angle θ of the steering wheel 301, ensuring steering operability by the driver.

[0058] In addition, the MCU 401 is configured to control the steering actuator 304 based on the target steering angle σtgf after processing the target steering angle σtgf with a first-order delay element, for example, and the drive speed can be made variable by changing the time constant of the first-order delay element. Furthermore, the MCU 401 can vary the drive speed by changing the gain in the calculation process of the control signal for the steering actuator 304 based on the difference between the target steering angle σtgf and the actual steering angle σ.

[0059] Furthermore, the MCU 401 can vary the drive speed when driving the steering actuator 304 in a direction that cancels the yaw rate γ of the vehicle 100, based on the deceleration caused by braking. When the deceleration acceleration due to braking is large, the yaw moment of the vehicle 100 increases rapidly, so if the response of the steering angle σ is slow, it may become difficult to sufficiently suppress the turning of the vehicle 100.

[0060] Therefore, the MCU 401 increases the drive speed of the steering actuator 304 when driving the steering actuator 304 in a direction that cancels the yaw rate γ of the vehicle 100 as the deceleration acceleration due to braking increases. This makes it possible to prevent the vehicle 100 from turning against the driver's will, even in the case of sudden braking.

[0061] The MCU 401 can determine the magnitude of the deceleration from the longitudinal acceleration detected by the acceleration sensor 408 or the brake fluid pressure (in other words, the amount of braking operation). That is, the MCU 401 can determine that the longitudinal acceleration detected by the acceleration sensor 408 is a negative acceleration and that the larger the absolute value is, the greater the deceleration acceleration is. Furthermore, the MCU 401 can determine that the higher the brake fluid pressure, the greater the deceleration acceleration.

[0062] "Second embodiment" The above-described first embodiment is a control assuming braking on a μ-split road surface. However, when driving force is generated by the drive unit 460 of the vehicle 100, for example, even when the vehicle 100 is accelerating at the start of a movement, there is a risk that the vehicle 100 will turn due to a difference in driving force between the left and right sides. Therefore, the MCU 401 can perform vehicle behavior control when driving force is generated by the drive unit 460 of the vehicle 100. The driving device 460 is an internal combustion engine, an electric motor, or the like. In the following, vehicle behavior control when a driving force is generated (in other words, during starting acceleration) will be described as a second embodiment.

[0063] The flowchart in FIG. 4 shows an example of a process for obtaining the yaw rate deviation γd in the second embodiment. Note that the flowchart in FIG. 4 differs from the flowchart in FIG. 2 only in the intervention condition determination process in step S554, and steps S551 to S553, step S555, and step S556 carry out processes similar to steps S501 to S503, step S505, and step S506 in the flowchart in FIG. 2.

[0064] Then, the MCU 401 performs the process of setting the target steering angle σtgf based on the yaw rate deviation γD obtained according to the flowchart of FIG. 4, according to the process shown in the flowchart of FIG. Therefore, only the intervention condition determination process in step S554 will be described in detail below.

[0065] In step S554, the MCU 401 determines whether or not the following first to fourth conditions are all satisfied. First condition: Yaw rate deviation γd is greater than or equal to a specified value Second condition: Driving force generation state Third condition: Vehicle speed V is equal to or greater than a certain speed Condition 4: Steering system is normal

[0066] Here, only the second condition among the four conditions in step S554 is different from the four conditions in step S504 of the flowchart in FIG. In other words, the first embodiment is vehicle behavior control assuming braking on a μ-split road surface, whereas the second embodiment is vehicle behavior control assuming starting acceleration on a μ-split road surface, and is vehicle behavior control for preventing the vehicle 100 from turning due to the difference in driving force between the left and right sides during starting acceleration.

[0067] The MCU 401 can detect the driving force generation state of the second condition as a state in which the longitudinal acceleration of the vehicle 100 is equal to or greater than a predetermined value (predetermined value>0). Furthermore, MCU 401 can detect the driving force generation state of the second condition as a state in which the depression amount or depression speed of the accelerator pedal operated by the driver is equal to or greater than a predetermined value. Furthermore, the MCU 401 can detect the driving force generation state of the second condition as a state in which the load of the driving device 460 is equal to or greater than a predetermined value.

[0068] When the vehicle 100 accelerates on a μ-split road surface, the vehicle 100 may turn to the side with the lower driving force due to the difference between the left and right driving forces. In such a case, in the second embodiment, the MCU 401 performs vehicle behavior control based on the satisfaction of the intervention condition, and controls the steering actuator 304 in a direction to cancel the yaw rate of the vehicle 100 so that the actual yaw rate γa approaches the target yaw rate γtg.

[0069] This makes it possible to prevent the vehicle 100 from turning against the driver's will when accelerating on a μ-split road surface, thereby improving the driving stability on the μ-split road surface. The MCU 401 can perform vehicle behavior control in both a braking state on a μ-split road surface and a driving force generation state on a μ-split road surface.

[0070] The technical ideas described in the above embodiments can be used in any suitable combination as long as no contradiction occurs. Furthermore, although the contents of the present invention have been specifically described with reference to preferred embodiments, it is obvious that a person skilled in the art can adopt various modified embodiments based on the basic technical concept and teachings of the present invention.

[0071] For example, the steer-by-wire steering device 300 may be a steering device equipped with a backup mechanism that mechanically couples the steering wheel 301 and the front wheels 101, 102 (in other words, the steering device 305) with a clutch or the like. Furthermore, the reaction force actuator 302 or the steering actuator 304 is not limited to an electric motor, but may be, for example, a steering device that uses a solenoid as an actuator.

[0072] Furthermore, the steering operation input member is not limited to the steering wheel 301, and the steering device may employ, for example, a joystick as the steering operation input member. In addition, the MCU 401 can change the predetermined value in the intervention condition (more specifically, the first condition) that the yaw rate deviation γd is equal to or greater than a predetermined value, based on the vehicle load, the degree of tire wear, the vehicle speed, the curvature of the curve, the driver's driving proficiency, etc. [Explanation of symbols]

[0073] 100...vehicle, 101, 102...front wheels (steered wheels), 200...steering system, 300...steering device (steer-by-wire), 301...steering wheel (steering operation input member), 303...steering member, 304...steering actuator, 305...steering device, 400...control device, 401...MCU (control unit), 407...yaw rate sensor, 411...operation angle sensor, 412...steering angle sensor

Claims

1. A steer-by-wire type steering device provided on a vehicle, the steer-by-wire type steering device having a steering operation input member and a steering actuator that applies a steering force to wheels of the vehicle, the steering operation input member and the steering device being mechanically separated, the steer-by-wire type steering device being provided on the vehicle and configured to be able to independently control the steering angle of the wheels in response to an operation amount of the steering operation input member, A control device for a steering device, comprising: a control unit having a vehicle behavior control that outputs a control signal to the steering actuator based on a physical quantity related to an operation amount of the steering operation input member, and corrects the steering angle with respect to the operation amount and outputs a control signal to the steering actuator, The control unit includes: Acquire a physical quantity related to a running state of the vehicle; acquiring a physical quantity related to a target yaw rate based on a physical quantity related to a running state of the vehicle and an operation amount of the steering operation input member; Calculating a yaw rate deviation (γd) by comparing an actual yaw rate based on a physical quantity related to a running state of the vehicle with the target yaw rate; When a predetermined intervention condition including the yaw rate deviation (γd) is satisfied in the vehicle behavior control, the yaw rate deviation (γd) is set as a yaw rate deviation (γD) to be used in the vehicle behavior control, and a control signal in a direction to cancel the yaw rate of the vehicle is output to the steering actuator so that the actual yaw rate approaches the target yaw rate. A control device for a steering device.

2. The steering device control device according to claim 1, The control unit includes: when a difference between the actual yaw rate and the target yaw rate becomes large, a control signal is output to the steering actuator in a direction to cancel the yaw rate of the vehicle so that the actual yaw rate approaches the target yaw rate. A control device for a steering device.

3. The control device for a steering device according to claim 2, The control unit includes: When a difference between the actual yaw rate and the target yaw rate falls within a predetermined range, a control signal is output to the steering actuator to set the steering angle of the wheels to a steering angle corresponding to an operation amount of the steering operation input member. A control device for a steering device.

4. The steering device control device according to claim 1, The control unit includes: outputting, to the steering actuator, a control signal in a direction to cancel the yaw rate of the vehicle so that the actual yaw rate approaches the target yaw rate when a braking force is generated by a braking device attached to the vehicle; A control device for a steering device.

5. The control device for a steering device according to claim 4, The control unit includes: When the vehicle stops, a control signal is output to the steering actuator to set the steering angle of the wheels to a steering angle corresponding to an operation amount of the steering operation input member. A control device for a steering device.

6. A steering device provided on a vehicle, the steering device having a steering operation input member and a steering actuator that applies a steering force to wheels of the vehicle, the steering device being configured to be able to independently control the steering angle of the wheels in response to an operation amount of the steering operation input member, A control device for a steering device, comprising: a control unit that outputs a control signal to the steering actuator based on a physical quantity related to an operation amount of the steering operation input member, The control unit includes: Acquire a physical quantity related to a running state of the vehicle; acquiring a physical quantity related to a target yaw rate based on a physical quantity related to a running state of the vehicle and an operation amount of the steering operation input member; comparing an actual yaw rate based on a physical quantity relating to a running state of the vehicle with the target yaw rate; outputting, to the steering actuator, a control signal in a direction to cancel the yaw rate of the vehicle so that the actual yaw rate approaches the target yaw rate when a braking force is generated by a braking device attached to the vehicle; outputting, to the steering actuator, a control signal for adjusting a steering angle of the wheels to a steering angle corresponding to an operation amount of the steering operation input member when the vehicle stops; a drive speed of the steering actuator when the steering angle of the wheels is set to a steering angle corresponding to the operation amount of the steering operation input member is made slower when the vehicle is stopped than when the vehicle is traveling; A control device for a steering device.

7. The steering device control device according to claim 4, The control unit includes: a driving speed when driving the steering actuator in a direction to cancel the yaw rate of the vehicle is varied based on the deceleration / acceleration of the vehicle; A control device for a steering device.

8. The steering device control device according to claim 4, The control unit includes: when braking by the braking device is completed, a control signal is output to the steering actuator to set the steering angle of the wheels to a steering angle corresponding to the operation amount of the steering operation input member. A control device for a steering device.

9. A steering device provided on a vehicle, the steering device having a steering operation input member and a steering actuator that applies a steering force to wheels of the vehicle, the steering device being configured to be able to independently control the steering angle of the wheels in response to an operation amount of the steering operation input member, A control device for a steering device, comprising: a control unit that outputs a control signal to the steering actuator based on a physical quantity related to an operation amount of the steering operation input member, The control unit includes: Acquire a physical quantity related to a running state of the vehicle; acquiring a physical quantity related to a target yaw rate based on a physical quantity related to a running state of the vehicle and an operation amount of the steering operation input member; comparing an actual yaw rate based on a physical quantity relating to a running state of the vehicle with the target yaw rate; outputting, to the steering actuator, a control signal in a direction to cancel the yaw rate of the vehicle so that the actual yaw rate approaches the target yaw rate when a braking force is generated by a braking device attached to the vehicle; when braking by the braking device is completed, outputting a control signal to the steering actuator to set the steering angle of the wheels to a steering angle corresponding to an operation amount of the steering operation input member; a drive speed of the steering actuator when the steering angle of the wheels is set to a steering angle corresponding to the operation amount of the steering operation input member is made faster while the vehicle is traveling than when the vehicle is stopped; A control device for a steering device.

10. The control device for a steering device according to claim 1, The control unit includes: outputting, to the steering actuator, a control signal in a direction that cancels the yaw rate of the vehicle so that the actual yaw rate approaches the target yaw rate when a driving force is generated by a driving device attached to the vehicle; A control device for a steering device.

11. The steering device control device according to claim 1, The control unit includes: when an abnormality occurs in the steering device, when the acceleration of the vehicle is equal to or greater than a predetermined value, or when the vehicle speed of the vehicle is less than a predetermined value, output of a control signal for bringing the actual yaw rate closer to the target yaw rate to the steering actuator is stopped. A control device for a steering device.

12. A control device for a steering device according to claim 1, The predetermined intervention conditions include the yaw rate deviation (γd), a braking state of a braking device attached to the vehicle or a driving state of a driving device attached to the vehicle, a speed of the vehicle, and a normal state of the steering device. A control device for a steering device.

13. A method for controlling a steering system, the method being executed by a control device provided in a vehicle equipped with a steer-by-wire type steering system, comprising: The steer-by-wire steering device is a steering device including a steering operation input member and a steering actuator that applies a steering force to wheels of the vehicle, the steering operation input member and the steering device being mechanically separated, and configured to be able to independently control the steering angle of the wheels in response to an operation amount of the steering operation input member; The method for controlling a steering device includes the steps of: a vehicle behavior control device that outputs a control signal to the steering actuator based on a physical quantity related to an operation amount of the steering operation input member, and corrects the steering angle with respect to the operation amount to output a control signal to the steering actuator, acquiring a physical quantity related to a running state of the vehicle; acquiring a physical quantity related to a target yaw rate based on a physical quantity related to a running state of the vehicle and an operation amount of the steering operation input member; A step of calculating a yaw rate deviation (γd) by comparing an actual yaw rate based on a physical quantity related to a running state of the vehicle with the target yaw rate; When a predetermined intervention condition including the yaw rate deviation (γd) is satisfied in the vehicle behavior control, the yaw rate deviation (γd) is set as a yaw rate deviation (γD) used in the vehicle behavior control, and a control signal in a direction to cancel the yaw rate of the vehicle is output to the steering actuator so that the actual yaw rate approaches the target yaw rate; Including, A method for controlling a steering device.

14. A steer-by-wire steering device provided in a vehicle, a steering device having a steering operation input member and a steering actuator that applies a steering force to wheels of the vehicle, the steering operation input member and the steering device being mechanically separated, and the steer-by-wire steering device being configured to be able to independently control the steering angle of the wheels in response to the operation amount of the steering operation input member; A control device, a control unit having a vehicle behavior control for outputting a control signal to the steering actuator based on a physical quantity related to an operation amount of the steering operation input member, and correcting the steering angle with respect to the operation amount and outputting a control signal to the steering actuator; The control unit includes: Acquire a physical quantity related to a running state of the vehicle; acquiring a physical quantity related to a target yaw rate based on a physical quantity related to a running state of the vehicle and an operation amount of the steering operation input member; Calculating a yaw rate deviation (γd) by comparing an actual yaw rate based on a physical quantity related to a running state of the vehicle with the target yaw rate; When a predetermined intervention condition including the yaw rate deviation (γd) is satisfied in the vehicle behavior control, the yaw rate deviation (γd) is set as a yaw rate deviation (γD) to be used in the vehicle behavior control, and a control signal in a direction to cancel the yaw rate of the vehicle is output to the steering actuator so that the actual yaw rate approaches the target yaw rate. The control device; A steering system having

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