JP4635661B2 - Vehicle steering system - Google Patents

Description

  The present invention relates to a steer-by-wire vehicle steering apparatus.

  In recent years, the steered wheel and the steering (steering wheel) are mechanically separated, and based on the detected steering angle (steering angle), the steering wheel (steering angle) of the steered wheel according to the steering operation is generated. In order to achieve this, a so-called steer-by-wire vehicle steering apparatus that controls the operation of the steering actuator has been proposed.

  By the way, in such a steer-by-wire vehicle steering apparatus, usually, the target turning angle is calculated based on the steering angle, and the operation of the turning actuator is controlled so that the actual turning angle follows the target turning angle. The However, since the steered wheels and the steering are separated, the road surface reaction force acting on the steered wheels due to the generation of the steered angle is not transmitted to the steering. Therefore, there is a problem that the driver cannot sense road surface information (road information) via the steering reaction force acting on the steering.

Therefore, conventionally, the steering torque applied to the steering and the road reaction force acting on the steered wheel are detected in order to reflect the road reaction force acting on the steered wheel as steering reaction force on the steering, and the steering torque and road reaction force are detected. Some control the operation of a reaction force actuator so as to apply a steering reaction force corresponding to the force to the steering (see, for example, Patent Document 1). Further, the integral effect of the feedback control is increased or decreased according to the driving state or the road surface state of the vehicle, and the steady deviation is changed. For example, when driving on rough roads with many irregularities, the integral effect is enhanced and smooth steering is performed. Some perform securing feelings (see, for example, Patent Document 2).
JP 2004-34923 A Japanese Patent Laid-Open No. 2004-210024

  By the way, when traveling on rough roads when the steered wheels pass through the unevenness on the road surface, a large road surface reaction force (reverse input stress) is instantaneously applied to the steered wheels at the time of entering and exiting. Here, in the case of a steering device in which a conventional steered wheel and a steering are mechanically coupled, the reverse input stress is transmitted to the steering through a mechanical coupling mechanism, and the stress is caused by the rotation of the steering. Is absorbed. However, the steer-by-wire vehicle steering system does not have a path for releasing the reverse input stress when passing through the unevenness, and is positioned so as to reduce the deviation between the target turning angle and the actual turning angle caused by the reverse input stress. By controlling, excessive stress is applied to the steering actuators constituting the steering mechanism and the connecting members (steering shafts, tie rods, knuckle arms, etc.) between the steered wheels. And this tendency becomes more remarkable by strengthening position control like the above-mentioned conventional example. For this reason, a higher strength than that of the conventional type is required for the connecting member or the ball screw that connects the connecting member and the steering actuator, and as a result, the weight increases to ensure the strength. There is a problem of end.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a vehicle steering apparatus that can relieve reverse input stress acting on a steering mechanism and ensure high durability. It is to provide.

  In order to solve the above problems, the invention according to claim 1 is to generate a steering mechanism having a steering mechanically separated from the steered wheels and a steered angle of the steered wheels according to a steering operation. A vehicle comprising a steering mechanism having a steered actuator to be controlled, and a control means for controlling the operation of the steered actuator, wherein the control means controls the position so that the actual turning angle follows the target turning angle. And a reverse input stress determining means for determining the magnitude of the reverse input stress acting on the steering mechanism, wherein the control means is a reverse input indicating the magnitude of the determined reverse input stress. The gist is to reduce the feedback gain of the position control when the stress judgment value exceeds a predetermined threshold.

  The invention according to claim 2 is provided with an axial force detecting means for detecting an axial force acting on a connecting member that connects the steered wheel and the steered actuator, and the reverse input stress determining means is the detected The gist is to determine the magnitude of the reverse input stress based on at least one of an axial force or a change rate of the axial force.

  The invention according to claim 3 is provided with a road surface reaction force detecting means for detecting a road surface reaction force acting on the steered wheel, and the reverse input stress determination means is configured to detect the detected road surface reaction force or the road surface reaction force. The gist is to determine the magnitude of the reverse input stress based on at least one of the change rates.

  According to a fourth aspect of the present invention, there is provided a steering angle detecting means for detecting a steering angle of the steering, an axial force detecting means for detecting an axial force acting on a connecting member that connects the steered wheel and the steered actuator. The control means calculates the target turning angle based on the detected steering angle, and the reverse input stress determination means detects the detected change in the axial force change rate. The gist is to determine the magnitude of the reverse input stress based on the ratio of the change speed of the steering angle.

  The invention according to claim 5 includes a steering angle detecting means for detecting a steering angle of the steering, and a road surface reaction force detecting means for detecting a road surface reaction force acting on the steered wheel, wherein the control means The target turning angle is calculated based on the detected steering angle, and the reverse input stress determination means is a ratio of the detected steering angle change speed to the detected road surface reaction force change speed. And determining the magnitude of the reverse input stress based on the above.

  The invention according to claim 6 is provided with a steering angle detecting means for detecting a steering angle of the steering, and the control means calculates the target turning angle based on the detected steering angle, The gist of the reverse input stress determination means is to determine the magnitude of the reverse input stress based on a ratio of the detected change speed of the steering angle to the change speed of the actual turning angle.

  The invention according to claim 7 comprises a reaction force actuator for applying a steering reaction force to the steering, and the control means applies the steering reaction force according to the detected road surface reaction force to the steering. Therefore, the gist is to control the operation of the reaction force actuator.

  The invention according to claim 8 comprises a reaction force actuator for applying a steering reaction force to the steering and a road surface reaction force detection means for detecting a road surface reaction force acting on the steered wheels, the control means comprising: The gist is to control the operation of the reaction force actuator so as to apply the steering reaction force according to the detected road surface reaction force to the steering.

  According to each of the above configurations, when a large reverse input stress acts on the steering mechanism, the followability of the actual turning angle with respect to the target turning angle is weakened, and thereby the reverse input acting on the turning mechanism. Stress can be effectively relieved. Accordingly, it is possible to prevent an excessive load from being applied to the connecting member between the steered actuator and the steered wheels constituting the steered mechanism, and to improve the durability thereof, and thus to reduce the weight of the entire steered mechanism. Can be achieved. Note that the determination of the magnitude of the reverse input stress, that is, the calculation of the reverse input stress determination value can be performed according to any one of claims 2 to 6, and in particular, the configuration according to claims 4 to 6. According to this, the reverse input stress acting on the steering mechanism can be determined with higher accuracy including the relaxation effect due to the rotation of the steering. Therefore, as in the configurations of the seventh and eighth aspects, the road surface reaction force applied to the steered wheels as a reverse input is reflected on the steering as the steering reaction force. Gain reduction can be made even more effective.

The gist of the invention described in claim 9 is that the control means decreases the feedback gain as the reverse input stress determination value greatly exceeds the threshold value.
According to the above configuration, as the reverse input stress acting on the steering mechanism is larger, the followability of the actual turning angle with respect to the target turning angle can be weakened, and the mitigation thereof can be achieved more effectively.

The gist of the invention described in claim 10 is that the control means holds the reduced feedback gain value until a predetermined time elapses.
According to the above configuration, the reverse input stress can be stably relieved even when the reverse input stress fluctuates intermittently, such as when the vehicle continuously passes through the unevenness when traveling on a rough road.

  The gist of the invention described in claim 11 is that, after the feedback gain is reduced, the control means gradually increases the reduced feedback gain over time.

  According to the above configuration, it is possible to prevent deterioration of the steering feeling due to a steep change in the followability of the actual turning angle with respect to the target turning angle.

  ADVANTAGE OF THE INVENTION According to this invention, the steering apparatus for vehicles which can relieve | moderate the reverse input stress which acts on a steering mechanism, and can ensure high durability can be provided.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment in which the present invention is embodied in a steer-by-wire vehicle steering device (steering device) will be described with reference to the drawings.
As shown in FIG. 1, in the steering device 1 of this embodiment, a steering mechanism 3 including a steering (handle) 2 and a steering mechanism 5 for changing the steering angle of the steered wheels 4 are mechanically disconnected. That is, this is a so-called steer-by-wire vehicle steering device in which the steering wheel 2 and the steered wheels 4 are mechanically separated.

  The steering mechanism 3 includes a steering shaft 6 to which the steering 2 is fixed, and a steering angle sensor 7 as a steering angle detection means for detecting the steering angle of the steering 2 accompanying the steering operation, that is, the steering angle θs. . The steering mechanism 5 includes a steering actuator 8 for generating a steering angle of the steered wheels 4 corresponding to the steering operation based on the steering angle θs detected by the steering angle sensor 7. In this embodiment, the steered mechanism 5 has a steered shaft 12 that connects the left and right steered wheels 4 via a tie rod 9 and a knuckle arm 10, and the steered actuator 8 is a motor 13 as a drive source. And a conversion mechanism 14 that converts the rotation of the motor 13 into the reciprocating motion of the steered shaft 12. The steered actuator 8 of this embodiment includes a brushless motor that is coaxially disposed with the steered shaft 12 and includes a ball screw mechanism as the conversion mechanism 14. Then, the reciprocating motion of the steered shaft 12 driven by the steered actuator 8 is transmitted to the steered wheels 4, so that the steered angle of the steered wheels 4, that is, the steered angle θt is changed. Yes.

  In the present embodiment, the steering mechanism 3 includes a torque sensor 16 as a steering torque detection means for detecting the steering torque τ applied to the steering wheel 2 by a steering operation, and the detected steering torque τ (and will be described later). And a reaction force actuator 17 for applying a steering reaction force corresponding to the road surface reaction force Fr) to the steering wheel 2. The reaction force actuator 17 includes a motor 18 as a drive source and a speed reduction mechanism 19 that decelerates the rotation of the motor 18 and transmits it to the steering shaft 6. In the present embodiment, a brushless motor is employed as the motor 18 of the reaction force actuator 17 in the same manner as the motor 13 of the steering actuator 8. The reaction force actuator 17 transmits a motor torque generated by the motor 18 to the steering shaft 6 via the speed reduction mechanism 19 to apply a steering reaction force to the steering 2.

  In the present embodiment, the operation of the steering actuator 8 and the reaction force actuator 17 is controlled by the control device 20. More specifically, the motor 13 of the steering actuator 8 and the motor 18 of the reaction force actuator 17 are connected to the control device 20, and each of the motors 13 and 18 has three phases (U, V) supplied from the control device 20. , W) based on the driving power. And the control apparatus 20 controls the action | operation of the steering actuator 8 and the reaction force actuator 17 by controlling rotation of each motor 13 and 18 through the supply of the drive electric power. Specifically, the control device 20 detects the steering angle θs, the steering torque τ, and the vehicle speed V based on the output signals from the steering angle sensor 7, the torque sensor 16, and the vehicle speed sensor 21. Further, the turning shaft 12 is provided with a displacement amount sensor 22, and the control device 20 determines the turning angle θt of the steered wheels 4 based on the output signal of the displacement amount sensor 22. Twelve axial displacement amounts X are detected. Then, the control device 20 controls the operation of the steered actuator 8 to change the steered angle θt of the steered wheels 4 based on the detected steering angle θs, vehicle speed V, and displacement X, and the steering torque τ Based on the vehicle speed V (and the road surface reaction force Fr), the operation of the reaction force actuator 17 is controlled to apply the steering reaction force.

Next, control modes of the steering actuator 8 and the reaction force actuator 17 by the control device 20 will be described.
FIG. 2 is a control block diagram of the steering device 1 of the present embodiment. As shown in the figure, the control device 20 includes a first ECU 23 for controlling the steering actuator 8 and a second ECU 24 for controlling the reaction force actuator 17. The first ECU 23 and the second ECU 24 supply microcomputers 25 and 26 that output motor control signals for controlling the motors 13 and 18, respectively, and supply driving power to the motors 13 and 18 based on the motor control signals. Drive circuits 27 and 28. Each control block in the microcomputers 25 and 26 shown below is realized by a computer program executed by the microcomputers 25 and 26.

  First, the configuration of the microcomputer 25 on the first ECU 23 side that controls the steering actuator 8 will be described. The microcomputer 25 generates a displacement amount command calculation unit 31 that generates a displacement amount command X * of the steered shaft 12 corresponding to the target turning angle of the steered wheels 4, and uses the displacement amount command X * and the detected displacement amount X. A position control calculation unit 32 that calculates a position control amount ε based on the position control amount ε and a motor control signal generation unit 33 that generates a motor control signal to be output to the drive circuit 27 based on the position control amount ε are provided.

  The steering angle θs and the vehicle speed V are input to the displacement amount command calculating unit 31, and the displacement amount command calculating unit 31 generates a displacement amount command X * based on the steering angle θs and the vehicle speed V, and the displacement amount command X * is output to the position control calculation unit 32. The displacement control unit 32 receives the displacement X detected by the displacement sensor 22 together with the displacement command X *. Then, the position control calculation unit 32 calculates the position control amount ε by feedback control based on the displacement amount command X * and the displacement amount X. Specifically, the position control calculation unit 32 includes an F / B calculation unit 34, and the F / B calculation unit 34 performs feedback based on a deviation ΔX between the displacement amount command X * and the displacement amount X. A control calculation (PI control) is executed. The position control calculation unit 32 outputs the output value of the F / B calculation unit 34 to the motor control signal generation unit 33 as the position control amount ε. The motor control signal generation unit 33 receives the actual current value detected by the current sensor 35 and the rotation angle of the motor 13 detected by the rotation angle sensor 36 along with the position control amount ε calculated by the position control calculation unit 32. Is done. The motor control signal generation unit 33 generates a motor control signal based on the position control amount ε, the actual current value, and the rotation angle, and outputs the motor control signal to the drive circuit 27. Then, when a drive current corresponding to the motor control signal is supplied to the motor 13, the rotation of the motor 13, that is, the turning of the turning actuator 8, to make the turning angle θt of the steered wheels 4 follow the target turning angle. Operation is controlled.

  On the other hand, the microcomputer 26 on the second ECU 24 side that controls the reaction force actuator 17 outputs the steering reaction force command Iq * as the control target amount of the steering reaction force applied to the steering 2, that is, the current command value of the drive current supplied to the motor 18. A steering reaction force command generation unit 41 for calculating and a motor control signal generation unit 42 for generating a motor control signal to be output to the drive circuit 28 based on the steering reaction force command Iq * are provided.

  In the present embodiment, the microcomputer 26 includes a road surface reaction force estimation calculation unit 43 that estimates the road surface reaction force Fr acting on the steered wheels 4, and the steering reaction force command generation unit 41 estimates the road surface reaction force. A steering reaction force command Iq * is calculated based on the road surface reaction force Fr estimated by the calculation unit 43. That is, in the present embodiment, the road surface reaction force estimation calculation unit 43 constitutes a road surface reaction force detection means. Then, drive power based on the steering reaction force command Iq * is supplied to the motor 18, that is, the operation of the reaction force actuator 17 is controlled, and the road reaction force Fr acting on the steered wheels 4 is controlled (road surface reaction force Fr). The steering reaction force is reflected on the steering 2.

  More specifically, in this embodiment, the road surface reaction force estimation calculation unit 43 is energized to the displacement X and the actual current value of the motor 13 detected by the current sensor 35, that is, the motor 13 on the steering actuator 8 side. The actual current value is input. Then, the road surface reaction force estimation calculation unit 43 calculates an axial force acting on the steered shaft 12 based on the displacement amount X and the actual current value, and the road surface reaction force Fr acting on the steered wheel 4 with the axial force. presume. A steering torque τ and a vehicle speed V are input to the steering reaction force command generation unit 41 together with the road surface reaction force Fr estimated by the road surface reaction force estimation calculation unit 43. The steering reaction force command generation unit 41 calculates a steering reaction force command Iq * based on the steering torque τ, the road surface reaction force Fr, and the vehicle speed V, and uses the steering reaction force command Iq * as a motor control signal generation unit. Output to 42. The motor control signal generator 42 is supplied with the steering reaction force command Iq * and the actual current value detected by the current sensor 44 and the rotation angle of the motor 18 detected by the rotation angle sensor 45. Then, the motor control signal generation unit 42 generates a motor control signal based on the steering reaction force command Iq *, the actual current value, and the rotation angle, and outputs the motor control signal to the drive circuit 28. A drive current having a current value corresponding to the motor control signal is supplied to the motor 18, whereby a steering reaction force corresponding to the steering torque τ, the road surface reaction force Fr, and the vehicle speed V is applied to the steering 2. It has become so.

(Variable feedback gain control when driving on rough roads)
Next, feedback gain variable control during rough road traveling in the present embodiment will be described. As described above, when the steered wheels pass through the irregularities on the road surface when traveling on rough roads, a large road surface reaction force (reverse input stress) is instantaneously applied to the steered wheels when entering and exiting. The And, by controlling the position so as to reduce the deviation between the target turning angle and the actual turning angle caused by the reverse input stress, excessive stress is applied to the connecting member between the turning actuator and the turning wheel. It will be.

  In view of this point, in the present embodiment, the control device 20 (the microcomputer 25 on the first ECU 23 side) includes the steered mechanism 5, more specifically, the steered actuator 8 (the ball screw, etc.) and the turning mechanism 5 constituting the steered mechanism 5. The magnitude of the reverse input stress acting on the connecting member (the steered shaft 12, the tie rod 9, the knuckle arm 10, etc.) between the steerable wheels 4 is determined. As shown in FIG. 3, when the magnitude of the determined reverse input stress, specifically, when the reverse input stress determination value δ indicating the magnitude exceeds a predetermined threshold value δ0, control of the turning actuator 8 is performed. That is, the feedback gain (F / B gain) Kfb in the position control of the turning angle θt is reduced. And the reverse input stress which acts on the steering mechanism 5 is relieve | moderated by weakening the followability of the actual turning angle with respect to a target turning angle.

  More specifically, as shown in FIG. 2, in this embodiment, the microcomputer 25 has an F / B gain variable calculation unit 50, and the F / B calculation unit 34 includes the F / B gain variable calculation unit. The feedback control calculation is executed based on the feedback gain Kfb output by 50. Then, the F / B gain variable calculation unit 50 varies the output feedback gain Kfb based on the magnitude of the reverse input stress acting on the steering mechanism 5.

  More specifically, in this embodiment, the F / B gain variable calculation unit 50 has a function as a reverse input stress determination unit that determines the magnitude of the reverse input stress acting on the steering mechanism 5. In the present embodiment, the F / B gain variable calculating unit 50 uses the differential value αFr (time) of the road surface reaction force Fr as the angular velocity ωs of the steering wheel 2 and the change speed of the estimated (detected) road surface reaction force Fr. The differential value) is input, and the F / B gain variable calculation unit 50 calculates the reverse input stress determination value δ based on the differential value αFr of the angular velocity ωs and the road surface reaction force Fr. Specifically, the reverse input stress is based on the ratio of the angular speed ωs (absolute value) to the differential value αFr (absolute value) of the road surface reaction force Fr, that is, the ratio of the change speed of the steering angle θs to the change speed of the road surface reaction force Fr. The judgment value δ is calculated (δ = | αFr | / | ωs |). When the reverse input stress determination value δ exceeds a predetermined threshold value δ0 (for example, 500 N / deg), the feedback gain Kfb output to the F / B calculation unit 34 is changed from the normal value Kfb0 to the normal value Kfb0. Variable to a low reduction value Kfb1.

  As shown in FIG. 4, in this embodiment, the F / B gain variable calculation unit 50 reduces the feedback gain Kfb and then reduces the value until a predetermined time t1 (for example, 100 milliseconds) elapses. This value is held at the reduced value Kfb1. After the elapse of the predetermined time t1, the feedback gain Kfb is gradually increased (gradually changed) from the reduced value Kfb1 to the normal value Kfb0 with time.

  Specifically, as shown in the flowchart of FIG. 5, the microcomputer 25 (the F / B gain variable calculation unit 50) first holds whether or not the feedback gain Kfb is already being reduced, that is, the reduction value Kfb1. It is determined whether or not (step 101). In the present embodiment, whether or not the reduction is being performed is determined based on whether or not a holding flag described later is set. And when it determines with not reducing (step 101: NO), the reverse input stress determination value (delta) is calculated (step 102).

  Next, the microcomputer 25 determines whether or not the reverse input stress determination value δ calculated in step 102 exceeds a predetermined threshold value δ0 (step 103). When it is determined that the reverse input stress determination value δ exceeds the predetermined threshold value δ0 (δ> δ0, step 103: YES), the timer is reset (t = 0, step 104), and the holding flag is set ( After step 105), the feedback gain Kfb is reduced from the normal value Kfb0 to the reduced value Kfb1 (step 106). If it is determined in step 101 that reduction has already been performed (step 101: YES), the microcomputer 25 does not execute the processing of steps 102 to 106, and the steps after step 108 shown below. Execute the process.

  When it is determined in step 103 that the reverse input stress determination value δ is equal to or smaller than the predetermined threshold value δ0 (δ ≦ δ0, step 103: NO), the microcomputer 25 continues to gradually change the feedback gain Kfb. It is determined whether or not (step 107). Whether or not this gradual change is in progress is determined by whether or not a gradual change flag described later is set. If it is determined that the gradual change is already being performed (step 107: YES), the microcomputer 25 executes the process after step 112 without executing the process after step 104 to step 111, and during the gradual change. If it is determined that this is not the case (step 107: NO), the processing from step 104 to step 106 and step 108 and thereafter is not executed.

  Next, when the feedback gain Kfb is reduced in the above step 106 or when it is determined that the feedback gain is already being reduced in the above step 101, the microcomputer 25 next increments the timer (t = t + 1, step 108). Subsequently, it is determined whether or not a predetermined time t1 has elapsed (step 109). If it is determined that the predetermined time t1 has elapsed (t ≧ t1, step 109: YES), the holding flag is reset (step 110) and the gradual change flag is set (step 111). When it is determined in step 109 that the predetermined time t1 has not yet elapsed (t <t1, step 109: NO), the above-described step 101 is performed for each scheduled interrupt until it is determined that the predetermined time t1 has elapsed. , Step 108 and Step 109 are executed.

  Next, if the gradual change flag is set in step 111 or if it is determined in step 107 that the gradual change is already in progress, the microcomputer 25 gradually increases the feedback gain Kfb from the reduced value Kfb1 to the normal value Kfb0. / B gain gradual change control is executed (step 112). Then, the microcomputer determines whether or not the feedback gain Kfb has recovered to the normal value Kfb0 by this F / B gain gradual change control (step 113). When it is determined that the feedback gain Kfb has recovered to the normal value Kfb0 (Kfb = Kfb0, step 113). : YES), the gradual change flag is reset and the series of feedback gain variable control is terminated (step 114).

As described above, according to the present embodiment, the following features can be obtained.
(1) The control device 20 (the microcomputer 25 on the first ECU 23 side) determines the magnitude of the reverse input stress acting on the steering mechanism 5. When the magnitude of the determined reverse input stress, specifically, the reverse input stress determination value δ indicating the magnitude exceeds a predetermined threshold value δ0, the steering actuator 8 is controlled, that is, the position of the turning angle θt. The feedback gain (F / B gain) Kfb in the control is reduced.

  With such a configuration, when it is determined that a large reverse input stress acts on the steering mechanism 5, the followability of the actual turning angle with respect to the target turning angle is weakened. 5 can effectively relieve the reverse input stress acting on 5. That is, it is the same principle that a carriage with a larger “wheel mounting backlash” is harder to break. Accordingly, an excessive load is applied to the steering actuator 8 (the ball screw thereof) and the connecting member (the steering shaft 12, the tie rod 9, the knuckle arm 10, etc.) between the steering actuator 8 and the steered wheels 4 constituting the steering mechanism 5. Can be prevented and the durability thereof can be improved, and the weight of the entire steering mechanism can be reduced.

  (2) The F / B gain variable calculation unit 50 has a ratio of the angular velocity ωs (absolute value) to the differential value αFr (absolute value) of the road surface reaction force Fr, that is, the change speed of the steering angle θs with respect to the change speed of the road surface reaction force Fr. Based on the ratio, the reverse input stress judgment value δ is calculated (δ = | αFr | / | ωs |).

  With such a configuration, the reverse input stress acting on the steering mechanism 5 can be determined with higher accuracy. That is, in this embodiment, since the steering reaction force according to the road surface reaction force Fr is applied to the steering 2, the road surface reaction force Fr applied to the steered wheels 4 as a reverse input is applied to the steering 2 as the steering reaction force. The steering 2 may rotate by being reflected. In such a case, the target turning angle approaches the actual turning angle as the steering angle θs varies, so that the reverse input stress acting on the turning mechanism 5 is relatively small, and the feedback gain Kfb. The need to reduce is reduced. In this respect, by adopting the above-described configuration, it is possible to accurately determine the reverse input stress including the relaxation effect due to the rotation of the steering wheel 2, and as a result, it is possible to further reduce the feedback gain Kfb. can do.

  (3) After the feedback gain Kfb is reduced, the F / B gain variable calculation unit 50 holds the reduced value, that is, the reduced value Kfb1 until a predetermined time t1 elapses. With such a configuration, even when the reverse input stress fluctuates intermittently, such as when the vehicle continuously passes through unevenness when traveling on a rough road, the reverse input stress can be relaxed stably. .

  (4) After the lapse of the predetermined time t1, the F / B gain variable calculation unit 50 gradually increases (gradually changes) the feedback gain Kfb from the reduced value Kfb1 to the normal value Kfb0 over time. With such a configuration, it is possible to prevent deterioration in steering feeling due to a steep change in the followability of the actual turning angle with respect to the target turning angle.

In addition, you may change each said embodiment as follows.
In the present embodiment, the control device 20 as the control means includes a first ECU 23 for controlling the steering actuator 8 and a second ECU 24 for controlling the reaction force actuator 17. However, the present invention is not limited to this, and the control means for controlling the steered actuator 8 and the reaction force actuator 17 may have a configuration in which components corresponding to the first ECU 23 and the second ECU 24 are provided separately.

  In the present embodiment, the control device 20 controls the operation of the steered actuator 8 to change the steered angle θt of the steered wheels 4 based on the detected steering angle θs, vehicle speed V, and displacement amount X. It was. However, the present invention is not limited to this, and the steered actuator 8 only needs to be controlled based on at least the steering angle θs. The control device 20 controls the operation of the reaction force actuator 17 to apply the steering reaction force based on the steering torque τ and the vehicle speed V (and the road surface reaction force Fr). The parameters other than the road surface reaction force Fr are not limited to the steering torque τ and the vehicle speed V as long as a corresponding steering reaction force can be applied.

  In the present embodiment, the road surface reaction force estimation calculation unit 43 applies the turning shaft 12 to the turning shaft 12 based on the displacement amount X detected by the displacement amount sensor 22 and the actual current value of the motor 13 that is the drive source of the turning actuator 8. The acting axial force is calculated, and the axial force is estimated as the road surface reaction force Fr acting on the steered wheels 4. However, the present invention is not limited to this, and the road surface reaction force Fr may be estimated using the position control amount ε calculated by the position control calculation unit 32.

  The control device 20 controls the operation of the reaction force actuator using the estimated road surface reaction force Fr. The road surface reaction force Fr is an axis on which the turning shaft 12 acts using a strain gauge or the like. It may be configured to directly detect the road surface reaction force Fr, such as detecting a force.

The displacement amount X is not necessarily detected by the displacement amount sensor 22 but may be estimated from the rotation angle of the motor 13 detected by the rotation angle sensor 36.
In the present embodiment, the F / B gain variable calculation unit 50 has a function as a reverse input stress determination unit. However, the present invention is not limited to this, and the F / B gain variable calculation unit 50 may have only a function as the F / B gain variable means, and the reverse input stress determination means may be provided separately. In this case, it is not limited to the microcomputer 25 but may be provided inside the control device 20 and further outside the control device 20.

  In this embodiment, the reverse input is based on the ratio of the angular velocity ωs (absolute value) to the differential value αFr (absolute value) of the road surface reaction force Fr, that is, the ratio of the change speed of the steering angle θs to the change speed of the road surface reaction force Fr. The stress judgment value δ is calculated (δ = | αFr | / | ωs |). However, the present invention is not limited to this, and the reverse input stress determination value δ may be calculated based on at least one of the road surface reaction force Fr or the change speed of the road surface reaction force Fr (differential value αFr), and the actual turning angle ( The reverse input stress determination value δ may be calculated based on the ratio of the change speed of the steering angle θs to the change speed of the turning angle θt). Further, instead of the estimated (detected) road surface reaction force Fr, an axial force acting on a connecting member constituting the steered mechanism 5 such as the steered shaft 12 may be used. In this case, the road surface reaction force estimation calculation unit 43 can be used as the axial force detection means. The reciprocal of the ratio may be used, that is, δ ′ = | ωs | / | αFr |. In this case, “exceeding the threshold” means that the threshold is below the threshold. Not too long.

  In the present embodiment, when the reverse input stress determination value δ exceeds the predetermined threshold value δ0, the feedback gain Kfb is changed from the normal value Kfb0 to the reduced value Kfb1 lower than the normal value Kfb0. However, the present invention is not limited to this, and the feedback gain Kfb may be made smaller as the reverse input stress determination value δ greatly exceeds the threshold value δ0. Thereby, as the reverse input stress acting on the steering mechanism 5 is larger, the followability of the actual turning angle with respect to the target turning angle can be weakened, and the mitigation thereof can be more effectively mitigated.

  In the present embodiment, the F / B calculation unit 34 executes PI control (proportional / integral control) as feedback control calculation, but may execute PID control (proportional / integral / derivative control). Good. In the feedback gain variable control, any of the proportional term gain, integral term gain, and derivative term gain may be varied as the feedback gain.

The schematic block diagram of a steering device. The control block diagram of a steering device. Explanatory drawing which shows the aspect of feedback gain variable control. Explanatory drawing which similarly shows the aspect of feedback gain variable control. The flowchart which shows the process sequence of feedback gain variable control.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Steering device, 2 ... Steering (handle), 3 ... Steering mechanism, 4 ... Steering wheel, 5 ... Steering mechanism, 6 ... Steering shaft, 7 ... Steering angle sensor, 8 ... Steering actuator, 12 ... Steering shaft , 17 ... Reaction force actuator, 20 ... Control device, 21 ... Vehicle speed sensor, 22 ... Displacement sensor, 23 ... 1ECU, 25 ... Microcomputer, 32 ... Position control calculation part, θs ... Steering angle, ωs ... Angular velocity, θt ... Steering angle, Fr ... Road surface reaction force, αFr ... Differential value, X ... Displacement amount, X * ... Displacement amount command, ΔX ... Deviation, Kfb ... Feedback gain (F / B gain), Kfb0 ... Normal value, Kfb1 ... Decrease Value, δ ... Reverse input stress judgment value, δ0 ... Threshold value.

Claims (11)

A steering mechanism having a steering mechanically separated from the steered wheels, a steered mechanism having a steered actuator controlled to generate a steered angle of the steered wheels according to a steering operation, and a steering actuator Control means for controlling the operation, and the control means is a vehicle steering device that controls the position so that the actual turning angle follows the target turning angle,
Comprising reverse input stress determination means for determining the magnitude of reverse input stress acting on the steering mechanism;
The control means reduces the feedback gain of the position control when the reverse input stress determination value indicating the magnitude of the determined reverse input stress exceeds a predetermined threshold;
A vehicle steering apparatus characterized by the above. The vehicle steering apparatus according to claim 1,
An axial force detecting means for detecting an axial force acting on a connecting member that connects the steered wheel and the steered actuator;
The vehicular steering apparatus, wherein the reverse input stress determination means determines the magnitude of the reverse input stress based on at least one of the detected axial force or a change rate of the axial force. The vehicle steering apparatus according to claim 1,
Road surface reaction force detecting means for detecting the road surface reaction force acting on the steered wheels,
The vehicular steering apparatus, wherein the reverse input stress determination means determines the magnitude of the reverse input stress based on at least one of the detected road surface reaction force or a change speed of the road surface reaction force. The vehicle steering apparatus according to claim 1,
Steering angle detection means for detecting the steering angle of the steering;
An axial force detecting means for detecting an axial force acting on a connecting member that connects the steered wheel and the steered actuator;
The control means calculates the target turning angle based on the detected steering angle,
The reverse input stress determination means determines the magnitude of the reverse input stress based on a ratio of the detected steering angle change speed to the detected axial force change speed;
A vehicle steering apparatus characterized by the above. The vehicle steering apparatus according to claim 1,
Steering angle detection means for detecting the steering angle of the steering;
Road surface reaction force detecting means for detecting a road surface reaction force acting on the steered wheel,
The control means calculates the target turning angle based on the detected steering angle,
The reverse input stress determining means determines the magnitude of the reverse input stress based on a ratio of the detected steering angle change speed to the detected road surface reaction force change speed;
A vehicle steering apparatus characterized by the above. The vehicle steering apparatus according to claim 1,
Steering angle detection means for detecting the steering angle of the steering,
The control means calculates the target turning angle based on the detected steering angle,
The reverse input stress determination means determines the magnitude of the reverse input stress based on a ratio of the detected steering angle change speed to the actual turning angle change speed;
A vehicle steering apparatus characterized by the above. The vehicle steering apparatus according to claim 5,
Equipped with a reaction force actuator for applying steering reaction force to the steering wheel,
The control means controls the operation of the reaction force actuator to apply the steering reaction force according to the detected road surface reaction force to the steering;
A vehicle steering apparatus characterized by the above. In the vehicle steering apparatus according to claim 4 or 6,
A reaction force actuator for applying a steering reaction force to the steering;
Road surface reaction force detecting means for detecting a road surface reaction force acting on the steered wheel,
The control means controls the operation of the reaction force actuator to apply the steering reaction force according to the detected road surface reaction force to the steering;
A vehicle steering apparatus characterized by the above. In the steering device for vehicles according to any one of claims 1 to 8,
The vehicle steering apparatus according to claim 1, wherein the control unit decreases the feedback gain as the reverse input stress determination value greatly exceeds the threshold value. In the vehicle steering device according to any one of claims 1 to 9,
The vehicle steering apparatus, wherein the control means holds the reduced feedback gain value until a predetermined time elapses. In the vehicle steering device according to any one of claims 1 to 10,
The vehicle steering apparatus, wherein after the feedback gain is reduced, the control means gradually increases the reduced feedback gain over time.

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