JP2010163091A - Steering device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering device for a vehicle, further improving responsiveness, and achieving better steering property. <P>SOLUTION: An ECU 9 (microcomputer 21) in the steering device for a vehicle calculates a torque differential instruction angle θdt* as a compensation component based on a differential value of a steering torque τ input to steering. The torque differential instruction angle θdt* as a second compensation component is superimposed on a gear ratio variable instruction angle θgr* as a basic component, together with a differential steering instruction angle θls* as a first compensation component. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vehicle steering apparatus including a transmission ratio variable device.

  Conventionally, by adding a second rudder angle (ACT angle) of a steered wheel based on motor drive to the first rudder angle of a steered wheel based on a steering operation, the steering angle of the steering wheel (steering angle) and the rudder of the steered wheel There is a vehicle steering apparatus including a transmission ratio variable device that varies a transmission ratio (gear ratio) between an angle (steering angle) (see, for example, Patent Document 1). Usually, the control of such a transmission ratio variable device, that is, the calculation of the target value (ACT command angle) of the ACT angle controlled by driving the motor is a basic component (gear ratio variable control variable) based on the steering angle and the vehicle speed. ) Is added with a compensation component (differential steer control amount) based on the steering speed.

  In other words, the gear ratio variable control amount that is the basic component reduces the burden on the driver by increasing the change amount of the steering angle with respect to the steering operation at low vehicle speeds as shown in FIG. The steering gear ratio is changed so as to ensure high steering stability with a small change amount. Then, by superimposing the differential steer control amount which is a compensation component based on the steering speed, it is possible to achieve high responsiveness as shown in FIG. 15 and improve the steering characteristics.

  FIG. 15 is a diagram showing the transition of the steering angle and the yaw rate generated by the steering operation at the time of lane change as an example. In FIG. 15, the curve L1 shown by the solid line is the locus when the differential steer compensation control is executed. , L2 indicated by a two-dot chain line indicates a locus when the differential steer compensation control is not executed.

JP 2007-331705 A

  However, if the steering characteristic is to be raised to a higher level, the response to the steering operation is not sufficient even when the differential steer compensation control is executed, that is, the tracking of the ACT angle is sufficiently fast. It is difficult to say the situation, and there was still room for improvement in this respect.

  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 capable of further improving responsiveness and realizing more excellent steering characteristics. There is.

  In order to solve the above problem, the invention according to claim 1 is provided in the middle of a steering transmission system between a steering wheel and a steered wheel, and a motor is provided at a first rudder angle of the steered wheel based on a steering operation. A transmission ratio variable device that varies a transmission ratio between the steering wheel and the steered wheel by adding a second steering angle of the steered wheel based on driving, and a control unit that controls the operation of the transmission ratio variable device The control means superimposes a compensation component based on a steering speed generated by the steering operation on a basic component based on a steering angle and a vehicle speed of the steering, thereby obtaining a control target value of the second steering angle. A vehicle steering apparatus for calculating, comprising a detection means for detecting a steering torque input to the steering, wherein the control means is a second auxiliary unit based on a differential value of the steering torque. It calculates the components, that together with the compensation component based compensation component of the second the steering speed superimposed on the basic components, and the gist.

  That is, when the steering torque generated by the steering operation and the steering angle are compared in the time dimension, the steering torque is faster. Therefore, as in the above configuration, by executing compensation control based on the differential value of the steering torque indicating the amount of change, the phase of the control target value (target angle) of the second steering angle based on the motor drive is advanced ( It can be issued quickly). As a result, the responsiveness to the steering operation can be improved, and thus more excellent steering characteristics can be realized.

  The invention according to claim 2 includes a determination unit that determines the state of the steering operation, and at least one of the steering torque detected by the detection unit, the differential value thereof, and the second compensation component. One is a low-pass filter process, and the control unit changes the cutoff frequency of the low-pass filter process according to the state of the steering operation determined by the determination unit, Is the gist.

  That is, as described above, by executing the torque differential compensation control based on the differential value of the steering torque, the control target value (target angle) of the second rudder angle based on the motor drive can be quickly determined. By using these early state quantities as a basis, the influence of the noise becomes stronger. Therefore, the noise is removed by each low-pass filter process, but such a low-pass filter process is inherently accompanied by a phase lag. This will also hinder the “early target angle”.

  However, according to the above-described configuration, when the steering state is required to have higher responsiveness, the cut-off frequency is increased to suppress the phase delay associated with the execution of the low-pass filter process, while the particularly high response is achieved. In a steering state in which performance is not required, the cutoff frequency can be lowered to reduce the influence of noise. As a result, it is possible to achieve a good steering feeling while suppressing the influence of noise while ensuring the required high responsiveness.

  According to a third aspect of the present invention, when the steering operation state is cut, the control means sets a cutoff frequency of the low-pass filter processing, and a value when the steering operation state is cut back. Further, the gist is to make the value higher than the value in the case of the steering retention.

  According to the above configuration, only at the time of “cutting” where higher responsiveness is required, the phase lag associated with the execution of the low-pass filter process can be suppressed to improve the responsiveness, and in other states, the influence of noise can be suppressed. it can. As a result, the responsiveness can be effectively improved.

The gist of the invention described in claim 4 is that the control means changes the second compensation component in accordance with the vehicle speed.
According to the above-described configuration, for example, when the vehicle speed is in the middle vehicle speed region, the second compensation component is set to a large value only in a vehicle speed region where there is a high probability that steering operation is frequently performed. it can. As a result, it is possible to avoid the occurrence of problems in steering feeling such as a decrease in so-called steering rigidity due to excessive responsiveness, and to realize better steering characteristics.

The gist of the invention described in claim 5 is that the control means corrects the second compensation component so as to limit the amount of change of the second compensation component to a predetermined limit value or less. .
That is, the differential value of the steering torque may change steeply due to the input of shocking stress from the steered wheels such as so-called end contact or curb collision caused by excessive steering operation exceeding the limit of movement of the steered wheels. Thus, the second compensation component based on the differential value also changes suddenly.

  However, according to the above configuration, the amount of change of the second compensation component is limited within a predetermined limit value. As a result, it is possible to enjoy the effect of improving the responsiveness by introducing the torque differential compensation control while ensuring high stability.

The gist of the invention described in claim 6 is that the control means reduces the limit value of the amount of change in accordance with the increase in the vehicle speed.
That is, as the vehicle speed increases, the influence of the sudden change of the second compensation component on the behavior of the vehicle also increases. However, according to the above configuration, the limit value can be reduced in accordance with the permissible level of the target value sudden change that decreases as the vehicle speed increases. As a result, it is possible to ensure higher stability while maximally enjoying the responsiveness improvement effect by introducing the torque differential compensation control.

  According to the present invention, it is possible to provide a vehicle steering apparatus capable of further improving the responsiveness and realizing more excellent steering characteristics.

The schematic block diagram of the steering apparatus for vehicles in 1st Embodiment. Action | operation explanatory drawing of transmission ratio variable control. The operation explanatory view of transmission ratio variable control similarly. The control block diagram of the steering device for vehicles in a 1st embodiment. The flowchart which shows the aspect of a dead zone process. Explanatory drawing which shows the relationship between a vehicle speed and a vehicle speed gain. Explanatory drawing which shows the aspect of a guard process. The control block diagram of the steering device for vehicles in a 2nd embodiment. The flowchart which shows the aspect of steering state determination. The flowchart which shows the aspect of the cutoff frequency change of a low-pass filter. The control block diagram of the steering device for vehicles in a 3rd embodiment. The block diagram which shows schematic structure of a variation | change_quantity guard process part. Explanatory drawing which shows the relationship between a vehicle speed and a variation | change_quantity guard value. The operation explanatory view of variable gear ratio control. The operation explanatory view of differential steer control.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, in the vehicle steering apparatus 1 of the present embodiment, a steering shaft 3 to which a steering wheel 2 is fixed is connected to a rack 5 via a rack and pinion mechanism 4. The rotation of the shaft 3 is converted into a reciprocating linear motion of the rack 5 by the rack and pinion mechanism 4. Then, the steering angle of the steered wheels 6, that is, the steered angle is varied by the reciprocating linear motion of the rack 5, so that the vehicle traveling direction is changed.

  The vehicle steering apparatus 1 of the present embodiment is configured as a so-called rack assist type electric power steering apparatus (EPS) in which a motor 7 as a driving source thereof is arranged coaxially with the rack 5. The motor torque is converted into an axial pressing force by a ball screw mechanism (not shown) and transmitted to the rack 5, whereby the assist force can be applied to the steering system.

  Further, the vehicle steering apparatus 1 of the present embodiment has a variable transmission ratio that varies the transmission ratio (gear ratio) between the steering angle (steering angle) of the steering 2 and the steering angle (steering angle) of the steered wheels 6. A device 8 and an ECU 9 as control means for controlling the operation of the transmission ratio variable device 8 are provided.

  More specifically, the steering shaft 3 includes a first shaft 10 connected to the steering 2 and a second shaft 11 connected to the rack and pinion mechanism 4, and the transmission ratio variable device 8 includes the first shaft 10 and the first shaft 10. A differential mechanism 12 for connecting the two shafts 11 and a motor 13 for driving the differential mechanism 12 are provided. The transmission ratio variable device 8 adds the rotation driven by the motor to the rotation of the first shaft 10 accompanying the steering operation and transmits it to the second shaft 11, thereby inputting the steering shaft to the rack and pinion mechanism 4. 3 rotations can be increased (or decelerated).

  That is, as shown in FIGS. 2 and 3, the transmission ratio variable device 8 uses the steering angle (ACT angle θta) of the steered wheels based on the motor drive to the steered angle (steer steered angle θts) of the steered wheels 6 based on the steering operation. ) Is added, the transmission ratio between the steering wheel 2 and the steered wheels 6, that is, the ratio between the steering angle θs and the steered angle θt is varied.

  In this case, “addition” is defined to include not only addition but also subtraction, and so on. In addition, when the “ratio between the steering angle θs and the turning angle θt” is expressed as an overall gear ratio (steering angle θs / steering angle θt), the ACT angle θta in the same direction as the steering angle θts must be added. Thus, the overall gear ratio becomes small (large turning angle θt, see FIG. 2). Then, the overall gear ratio is increased by adding the ACT angle θta in the reverse direction (small turning angle θt, see FIG. 3).

  In this embodiment, a brushless motor is employed as the motor 13 that is a drive source of the transmission ratio variable device 8, and the motor 13 is a three-phase (U, V, W) supplied from the ECU 9. Rotates based on drive power. The ECU 9 is configured to control the operation of the transmission ratio variable device 8, that is, the ACT angle θta by controlling the rotation of the motor 13 through the supply of the drive power (transmission ratio variable control).

Next, the electrical configuration and control mode of the vehicle steering apparatus of the present embodiment will be described.
As shown in FIG. 1, the steering angle θs and the steering speed ωs detected by the steering angle sensor 16 and the vehicle speed V detected by the vehicle speed sensor 17 are input to the ECU 9. The ECU 9 supplies electric power to the motor 13 that is the driving source in order to control the operation of the transmission ratio variable device 8 based on the steering angle θs, the steering speed ωs, and the vehicle speed V, thereby Such a transmission ratio variable control is executed.

  More specifically, as shown in FIG. 4, the ECU 9 includes a microcomputer 21 that outputs a motor control signal and a drive circuit 22 that supplies drive power to the motor 13 based on the motor control signal.

  Each control block shown below is realized by a computer program executed by the microcomputer 21. Then, the microcomputer 21 detects each state quantity at a predetermined sampling period, and generates a motor control signal by executing each arithmetic processing shown in the following control blocks every predetermined period.

  The microcomputer 21 is provided with a gear ratio variable control calculation unit 23 and a differential steer control calculation unit 24. A steering angle θs and a vehicle speed V are input to the gear ratio variable control calculation unit 23, and the gear ratio variable control calculation unit 23 determines a gear ratio (transmission ratio) according to the vehicle speed V based on this. Is calculated, that is, a gear ratio variable command angle θgr * which is a basic component of transmission ratio variable control (see FIG. 14). On the other hand, the vehicle speed V and the steering speed ωs are input to the differential steer control calculation unit 24, and the differential steer control calculation unit 24 improves the responsiveness of the vehicle according to the steering speed ωs. The differential steer command angle θls *, which is the control target component, that is, the compensation component is calculated (see FIG. 15). In the present embodiment, the steering speed ωs is also input to the gear ratio variable control calculation unit 23, whereby an optimum transmission ratio can be determined based on the steering speed ωs. It is possible.

  The gear ratio variable command angle θgr * and the differential steer command angle θls * calculated by the gear ratio variable control calculation unit 23 and the differential steer control calculation unit 24 are input to the adder 25 and added by the adder 25. The Then, the microcomputer 21 determines the second steering angle based on the motor drive based on the value obtained by superposing the differential steering command angle θls * that is the compensation component on the gear ratio variable command angle θgr * that is the basic component. The ACT command angle θta *, which is a control target value for the ACT angle θta, is calculated.

  The ACT command angle θta * calculated in this way is calculated along with ACTθta calculated based on the output value of the rotation angle sensor 26 provided in the motor 13 of the transmission ratio variable device 8 that is the control target. Input to the unit 27. Then, the motor control signal calculation unit 27 of the present embodiment executes feedback control so that the actual ACT angle θta follows the ACT command angle θta * that is the control target value, that is, the motor is obtained by executing the position control calculation. Generate a control signal.

  Then, the microcomputer 21 outputs the motor control signal to the drive circuit 22, and the drive circuit 22 executes the supply of drive power based on the motor control signal, whereby the rotation of the motor 13, that is, the operation of the transmission ratio variable device 8 is performed. Is configured to be controlled.

(Torque differential compensation control)
Next, torque differential compensation control executed by the ECU 9 (microcomputer 21) as control means in the vehicle steering apparatus 1 of the present embodiment will be described.

  As described above, when calculating the ACT command angle θta *, which is the control target value of the second rudder angle, the differential steer command angle θls * as a compensation component with respect to the gear ratio variable command angle θgr * which is the basic component. By superimposing, a quick response to the steering operation can be realized and a good steering characteristic can be obtained. However, it is also true that further improvement of the responsiveness is inevitable if the steering characteristics are to be raised to a higher level.

  Based on this point, the ECU 9 (microcomputer 21) of the present embodiment calculates a compensation component based on the differential value of the steering torque τ input to the steering 2, and positions the second compensation component as the first compensation component. Is superimposed on the gear ratio variable command angle θgr * which is a basic component together with the differential steering command angle θls *. And it is the structure which aims at the further improvement of responsiveness by execution of the series of torque differential compensation control.

  That is, when the steering torque τ generated by the steering operation and the steering angle θs are compared in the time dimension, the dimension of the steering torque τ is equal to the dimension when the steering angle θs is second-order differentiated. Therefore, as described above, the control target value of the ACT angle θta is obtained by executing the compensation control based on the change amount of the steering torque τ in the time dimension, that is, the differential value of the steering torque (steering torque differential value dτ). The phase of the ACT command angle θta *, which is the (target angle), can be advanced (advanced). As a result, the responsiveness to the steering operation can be further improved.

  More specifically, as shown in FIG. 1, the torque transmitted to the vehicle steering apparatus 1 of the present embodiment via the steering shaft 3 constituting the steering transmission system, that is, the steering torque input to the steering 2. A torque sensor 29 capable of detecting τ is provided. The ECU 9 calculates a differential value (steering torque differential value dτ) based on the steering torque τ detected by the torque sensor 29, and executes a torque differential compensation calculation based on the differential value.

  In this embodiment, the steering torque detected by the torque sensor 29 is also used as a basis for EPS control using the motor 7 as a drive source, that is, power assist control.

  As shown in FIG. 4, the microcomputer 21 calculates a torque differential value calculation unit 31 for calculating the steering torque differential value dτ, and a torque differential command angle θdt * as a second compensation component based on the steering torque differential value dτ. And a torque differential control calculation unit 32.

  In this embodiment, the torque differential command angle θdt * output from the torque differential control calculation unit 32 is input to the adder 25, and the gear ratio variable command angle θgr * which is a basic component together with the differential steer command angle θls *. ACT command angle θta *, which is a control target value of ACT angle θta, is calculated.

  More specifically, the torque differential value calculation unit 31 of the present embodiment is provided with a filter processing unit (LPF: low pass filter) 33, and the torque differential value calculation unit 31 includes the filter processing unit 33. Low-pass filter processing is executed for the input steering torque τ. Then, the steering torque differential value dτ is calculated by differentiating the steering torque τ after the low-pass filter processing.

  On the other hand, the torque differential control calculation unit 32 is provided with a dead zone control unit 34, and the steering torque differential value dτ input to the torque differential control calculation unit 32 is first input to the dead zone control unit 34.

  As shown in the flowchart of FIG. 5, the dead zone controller 34 determines whether or not the absolute value of the input steering torque differential value dτ is equal to or less than a predetermined threshold value α set in the vicinity of “0” ( Step 101) If the absolute value is equal to or less than the threshold value α (| dτ | ≦ α, Step 101: YES), the steering torque differential value dτ is corrected to “0” (Step 101). 102). When the absolute value of the steering torque differential value dτ exceeds the threshold value α (| dτ |> α, Step 101: NO), the correction is not performed (Step 103).

  That is, by setting the steering torque differential value dτ, which is the basis of the torque differential compensation calculation, to “0”, the subsequent processing in the torque differential compensation calculation is substantially not performed. And in this embodiment, it becomes the structure which avoids generation | occurrence | production of the problem resulting from the detection error of steering torque (tau) by this.

  Further, the torque differential control calculation unit 32 is provided with a vehicle speed gain calculation unit 35, and the vehicle speed gain calculation unit 35 calculates a vehicle speed gain Kv that changes in accordance with the input vehicle speed V. Specifically, the vehicle speed gain calculating unit 35 of the present embodiment calculates a vehicle speed gain Kv having a larger value when the detected vehicle speed V is in the middle vehicle speed region, that is, in the vehicle speed region where the steering operation is frequently performed. It is comprised so that it may calculate (refer FIG. 6). In the present embodiment, the multiplier 36 calculates the basic amount ε of the torque differential command angle θdt * by multiplying the vehicle torque gain Kv by the steering torque differential value dτ. That is, according to the vehicle speed V, the value of the torque differential command angle θdt * is changed.

  In the present embodiment, the basic quantity ε calculated in this way is input to the guard processing unit 37. Then, the guard processing unit 37 performs guard processing so that the absolute value does not exceed a predetermined limit value ε_lim.

  Specifically, as shown in the flowchart of FIG. 7, the guard processing unit 37 first determines whether or not the absolute value of the input basic quantity ε exceeds a predetermined limit value ε_lim (step 201). When the limit value ε_lim is exceeded (| ε |> ε_lim, step 201: YES), the sign of the input basic quantity ε is determined (step 202), and the sign is changed without changing the sign. The basic amount ε is corrected so that the absolute value becomes the limit value ε_lim (steps 203 and 204).

  That is, when the sign of the basic quantity ε before correction is positive (ε> 0, step 202: YES), the basic quantity ε is corrected to “ε_lim” (step 203), and the sign is negative. (Ε <0, step 202: NO), the basic amount ε “−ε_lim” is corrected (step 204). In step 201, when the absolute value of the input basic quantity ε is equal to or smaller than a predetermined limit value ε_lim, the processing in steps 202 to 204 is not executed (no correction, step 205).

  Further, the torque differential control calculation unit 32 of the present embodiment is provided with a filter processing unit (LPF: low-pass filter) 38 similar to the torque differential value calculation unit 31, and in the guard processing unit 37 as described above. The basic amount ε subjected to the guard process is input to the filter processing unit 38. Then, based on the value after the low-pass filter processing is performed in the filter processing unit 38, the torque differential control calculation unit 32 calculates the torque differential command angle θdt * as the second compensation component based on the steering torque differential value dτ. It is the composition which calculates.

As described above, according to the present embodiment, the following operations and effects can be obtained.
(1) The ECU 9 (microcomputer 21) calculates the torque differential command angle θdt * as a compensation component based on the differential value of the steering torque τ input to the steering 2. Then, the torque differential command angle θdt * as the second compensation component is superimposed on the gear ratio variable command angle θgr * as the basic component together with the differential steer command angle θls * as the first compensation component.

  That is, when the steering torque τ generated by the steering operation and the steering angle θs are compared in the time dimension, the steering torque τ is faster. Therefore, as described above, by executing compensation control based on the amount of change in the steering torque τ, that is, the differential value of the steering torque (steering torque differential value dτ), the control target value (target angle) of the ACT angle θta is obtained. ), The phase of the ACT command angle θta * can be advanced (advanced). As a result, the responsiveness to the steering operation can be improved, and thus more excellent steering characteristics can be realized.

  (2) The microcomputer 21 includes a torque differential value calculation unit 31 that calculates the steering torque differential value dτ and a torque differential control calculation unit 32 that calculates the torque differential command angle θdt *. Is provided with a vehicle speed gain calculator 35 for calculating a vehicle speed gain Kv corresponding to the vehicle speed V. Then, the torque differential control calculation unit 32 calculates the basic amount ε of the torque differential command angle θdt * by multiplying the steering torque differential value dτ by the vehicle speed gain Kv.

  According to the above configuration, the value of the torque differential command angle θdt * is changed according to the vehicle speed V. As a result, for example, when the vehicle speed V is in the middle vehicle speed region, the responsiveness can be improved by setting the torque differential command angle θdt * to a large value only in the vehicle speed region where the steering operation is frequently performed. . As a result, it is possible to avoid the occurrence of problems in steering feeling such as a decrease in so-called steering rigidity due to excessive responsiveness, and to realize better steering characteristics.

(Second Embodiment)
Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. For convenience of explanation, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 8, in the vehicle steering apparatus 40 of the present embodiment, the microcomputer 41 is provided with a steering state determination unit 42 as a determination unit that determines the state of the steering operation (steering state) by the driver. Yes. In this embodiment, the cutoff frequency of the low-pass filter processing by the filter processing units 43 and 48 provided in the torque differential value calculation unit 31 and the torque differential control calculation unit 32 is changed according to the steering state. It is the composition which becomes.

  Specifically, in the present embodiment, the steering state determination unit 42 is input with the steering angle θs and the steering speed ωs, and the steering state determination unit 42 receives the steering angle θs and the steering speed. Based on the above, it is determined whether the steering state is “cut-in” or other “switch-back” or “steering”. Based on the result of the steering state determination, the cutoff frequency of the low-pass filter processing in each filter processing unit 43, 48 is changed.

  More specifically, as shown in the flowchart of FIG. 9, the steering state determination unit 42 first determines whether the detected steering speed ωs is greater than a predetermined threshold value (positive threshold value) having a positive sign. It is determined whether or not it has a positive value whose absolute value is larger than the threshold value (step 301). Next, when the value of the steering speed ωs is larger than the positive threshold value in step 301 (ωs> positive threshold value, step 301: YES), the steering state determination unit 42 further determines whether the sign of the steering angle θs is positive. It is determined whether or not (step 302). If the sign is positive (θs> 0, step 302: YES), it is determined that the steering state is “cut” (step 303).

  On the other hand, when the steering speed ωs is equal to or less than the positive threshold value in step 301 (ωs ≦ positive threshold value, step 301: NO), or the sign of the steering angle θs is not positive (θs ≦ 0, step 302: NO). The steering state determination unit 42 determines whether or not the steering speed ωs is smaller than a predetermined threshold (negative threshold) having a negative sign. That is, it is determined whether or not the steering speed ωs has a negative value whose absolute value is larger than the negative threshold value (step 304).

  Next, in step 304, when the value of the steering speed ωs is smaller than the negative threshold (ωs <negative threshold, step 304: YES), the steering state determination unit 42 further determines whether the sign of the steering angle θs is negative. It is determined whether or not (step 305). Even when the sign is negative (θs <0, step 305: YES), it is determined in step 303 that the steering state is “cut”.

In step 304, when the steering speed ωs is equal to or higher than the negative threshold (ωs ≧ negative threshold, step 304: NO), or when the sign of the steering angle θs is not negative (that is, θs = 0, step 305: NO). ), It is determined that the steering state is “switchback” or “steering” (step 306).
That is, the steering state determination unit 42 of the present embodiment has a magnitude that exceeds a predetermined threshold that the absolute value of the steering speed ωs is estimated not to be in the steered state, and the sign (direction) is the steering angle. When equal to θs, it is determined that the steering state is “cut”. And when this determination condition is not satisfy | filled, it is comprised so that it may determine with "switchback" or "steering".

  The steering state determination unit 42 of the present embodiment outputs the result of such steering state determination to the filter processing units 43 and 48 as a steering state signal Sst. And each filter process part 43 and 48 becomes a structure which changes the cutoff frequency of the low-pass filter process based on the steering state shown by the steering state signal Sst.

  Specifically, as shown in the flowchart of FIG. 10, each of the filter processing units 43 and 48 determines whether or not the steering state indicated by the input steering state signal Sst is “cut” (step). 401). When the steering state is “cut” (step 401: YES), the cutoff frequency is set to a high value (step 402), and when it is “switch back” or “steering” (step 401: NO) is configured to switch the cut-off frequency to a lower value (step 403).

  In the present embodiment, the cut-off frequency of each of the filter processing units 43 and 48 is higher in the value at the “cut-in” than the value at the “cut-back” or “steering”. It is configured.

  That is, as described above, when the steering torque τ generated by the steering operation and the steering angle θs are compared in the time dimension, the steering torque τ is faster. Therefore, by executing the torque differential compensation control based on the steering torque differential value dτ that is the differential value, the ACT command angle θta * that is the control target value (target angle) of the ACT angle θta can be quickly obtained. The influence of the noise is also strengthened by using such a state quantity with a fast dimension as a basis. Therefore, the torque differential value calculation unit 31 and the torque differential control calculation unit 32 are provided with the filter processing units 43 and 48 in order to perform low-pass filter processing for removing the noise.

  However, since such low-pass filter processing is inherently accompanied by a phase delay, if it is devoted to noise removal, the “target command angle θta *, which is the target angle”, which is originally intended, can be obtained. Will also interfere.

  Therefore, in the present embodiment, at the time of “cutting” in which higher responsiveness is required, the value of the cutoff frequency of the low-pass filter processing by the filter processing units 43 and 48 is set at the time of “switching back” or “steering”. Change to be higher than the value. As a result, it is configured to achieve the required high responsiveness while suppressing an increase in the influence of noise caused by using the steering torque differential value dτ.

As described above, according to the present embodiment, the following operations and effects can be obtained.
(1) The microcomputer 41 is provided with a steering state determination unit 42 as determination means for determining a state of steering operation (steering state) by the driver. Then, according to the steering state, the cutoff frequency of the low-pass filter processing by the filter processing units 43 and 48 provided in the torque differential value calculation unit 31 and the torque differential control calculation unit 32 is changed.

  That is, by executing the torque differential compensation control based on the steering torque differential value dτ, the ACT command angle θta *, which is the control target value (target angle), can be quickly obtained. As a result, the influence of the noise also becomes strong. Therefore, the noise is removed by low-pass filter processing by the filter processing units 43 and 48. Since such low-pass filter processing is inherently accompanied by a phase delay, This also hinders the “target angle quick start” that is originally intended.

  However, according to the above-described configuration, when the steering state is required to have higher responsiveness, the cut-off frequency is increased to suppress the phase delay associated with the execution of the low-pass filter process, while the particularly high response is achieved. In a steering state in which performance is not required, the cutoff frequency can be lowered to reduce the influence of noise. As a result, it is possible to achieve a good steering feeling while suppressing the influence of noise while ensuring the required high responsiveness.

  (2) When the steering state signal Sst input from the steering state determination unit 42 indicates “cut” (step 401: YES), the filter processing units 43 and 48 increase the cutoff frequency (step 402). ) And “switch back” or “steering” (step 401: NO), the cutoff frequency is switched to a lower value (step 403).

  According to the above configuration, only at the time of “cutting” where higher responsiveness is required, the phase lag associated with the execution of the low-pass filter process can be suppressed to improve the responsiveness, and in other states, the influence of noise can be suppressed. it can. As a result, the responsiveness can be effectively improved.

(Third embodiment)
Hereinafter, a third embodiment of the present invention will be described with reference to the drawings. For convenience of explanation, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 11, in the vehicle steering apparatus 50 of the present embodiment, the torque differential control calculation unit 52 provided in the microcomputer 51 includes a torque differential command angle θdt calculated by the torque differential control calculation unit 52. A change amount guard processing unit 53 is provided to suppress a sudden change in *. In the present embodiment, the variation guard processing unit 53 is interposed between the guard processing unit 37 and the filter processing unit 38. Then, the basic amount ε2 after the change amount guard processing by the change amount guard processing unit 53 is input to the filter processing unit 38.

  That is, the steering torque differential value dτ changes sharply by the input of shocking stress from the steered wheel 6 such as so-called end contact or curb collision caused by excessive steering operation exceeding the movable limit of the steered wheel 6. As a result, the torque differential command angle θdt * based on the steering torque differential value dτ also suddenly changes.

  Therefore, in the present embodiment, the change amount guard processing unit 53 sets the change amount (absolute value) of the basic amount ε of the torque differential command angle θdt * calculated based on the steering torque differential value dτ as a predetermined value. The change amount guard process is performed to limit the value within the limit value (change amount guard value). And in this embodiment, it is the structure which suppresses the sudden change of the torque differential command angle | corner (theta) dt * which the torque differential control calculating part 52 outputs by this.

  More specifically, as shown in FIG. 12, the change amount guard processing unit 53 is provided with a previous value holding unit 54 that holds the value of the basic amount ε input in the previous calculation cycle. The basic amount ε input to the change amount guard processing unit 53 in the cycle is input to the subtractor 55 together with the previous value εb output from the previous value holding unit 54. Then, the subtractor 55 calculates a difference value dε indicating the change amount of the basic amount ε by obtaining these differences.

  Next, the difference value dε indicating the change amount of the basic amount ε is input to the guard calculation unit 56, and the absolute value of the difference value dε does not exceed the change amount guard value in the guard calculation unit 56. The change amount guard process is limited to the above. Then, the change amount guard processing unit 53 adds the difference value dε ′ after the change amount guard process is performed in the guard calculation unit 56 to the previous value εb, and adds the difference value dε ′ after the change amount guard process. The basic amount ε2 is output to the filter processing unit 38.

  It should be noted that the mode of change amount guard processing and the processing procedure in the guard calculation unit 56 are the same as the guard processing (see FIG. 7) in the guard processing unit 37, and thus detailed description thereof is omitted.

  Here, the vehicle speed V is input to the guard calculation unit 56 of the present embodiment together with the difference value dε. The guard calculation unit 56 is configured to change the guard value (change amount guard value) of the change amount guard process executed by the guard calculation unit 56 based on the input vehicle speed V.

  Specifically, as illustrated in FIG. 13, the variation guard processing unit 53 of the present embodiment is configured to reduce the variation guard value (absolute value thereof) as the vehicle speed V increases. That is, as the vehicle speed V increases, the influence of the sudden change of the torque differential command angle θdt *, which is the target value of the torque differential compensation control, on the behavior of the vehicle also increases. Based on this point, in the present embodiment, the change amount guard value is reduced in accordance with the permissible level of the target value sudden change that decreases as the vehicle speed V increases. As a result, the structure is designed to ensure higher stability while maximally enjoying the effect of improving the response by introducing the torque differential compensation control.

As described above, according to the present embodiment, the following operations and effects can be obtained.
(1) A sudden change in the torque differential command angle θdt * calculated in the torque differential control calculation unit 52 is caused in the torque differential control calculation unit 52, specifically between the guard processing unit 37 and the filter processing unit 38. A change amount guard processing unit 53 for suppression is provided.

  That is, the steering torque differential value dτ changes abruptly by the input of shocking stress from the steered wheel 6 such as so-called end contact or curb collision caused by excessive steering operation exceeding the movable limit of the steered wheel 6. As a result, the torque differential command angle θdt * based on the steering torque differential value dτ also suddenly changes.

  However, according to the above configuration, the change amount of the basic amount ε of the torque differential command angle θdt * is limited within a predetermined guard value (change amount guard value). As a result, it is possible to enjoy the effect of improving the responsiveness by introducing the torque differential compensation control while ensuring high stability.

  (2) The vehicle speed V is input to the change amount guard processing unit 53 (guard calculation unit 56). The change amount guard processing unit 53 changes the guard value (change amount guard value) of the change amount guard process executed by the guard calculation unit 56 based on the input vehicle speed V.

  That is, as the vehicle speed V increases, the influence of the sudden change in the torque differential command angle θdt * on the behavior of the vehicle also increases. However, according to the above configuration, it is possible to reduce the change amount guard value in accordance with the permissible level of the target value sudden change that decreases as the vehicle speed V increases. As a result, it is possible to ensure higher stability while maximally enjoying the responsiveness improvement effect by introducing the torque differential compensation control.

In addition, you may change each said embodiment as follows.
In each of the above embodiments, the filter processing unit 33 (43) performs low-pass filter processing for the steering torque τ, and the filter processing unit 38 (48) performs low-pass filter processing for the basic amount ε (ε2) of the torque differential command angle θdt *. It was decided to be arranged to execute. However, such low-pass filter processing may be executed at least once in any of the processes from the steering torque τ to the torque differential command angle θdt *. That is, for example, the low-pass filter process may be performed at the stage of the steering torque differential value dτ, or may be executed a plurality of times in combination with other stages. In such a case, the change of the cut-off frequency in the second embodiment may be performed for at least one of the low-pass filter processes.

  In each of the above embodiments, the torque differential control calculation unit 32 (52) calculates the basic amount ε of the torque differential command angle θdt * by multiplying the steering torque differential value dτ by the vehicle speed gain Kv. However, the present invention is not limited to this, and the basic amount ε may be calculated by multiplying the vehicle speed gain Kv by a predetermined coefficient or a gain whose value changes depending on other state quantities. In the first embodiment, the vehicle speed gain Kv is set to be large when the vehicle speed V is in the medium vehicle speed region. However, when a gain that depends on other state quantities is used. Needless to say, the gain characteristic may be optimized as appropriate in accordance with the vehicle state quantity.

  In the third embodiment, the variation guard processing unit 53 is provided in the torque differentiation control calculation unit 52, specifically, between the guard processing unit 37 and the filter processing unit 38. However, the present invention is not limited to this. For example, the change amount guard processing unit 53 may be provided in a stage before the guard processing unit 37 in the torque differential control calculation unit 52 or a stage after the filter processing unit 38. Further, the configuration may be such that the sudden change in the torque differential command angle θdt * is more directly suppressed independent of the torque differential control calculation unit 52.

  In each of the above embodiments, although not particularly mentioned, the torque sensor 29 as the detection means may be a dedicated product of the transmission ratio variable device 8 or may be provided for EPS. Good.

  DESCRIPTION OF SYMBOLS 1,40,50 ... Vehicle steering device, 2 ... Steering, 3 ... Steering shaft, ... Rack, 6 ... Steering wheel, 8 ... Transmission ratio variable device, 9 ... ECU, 13 ... Motor, 16 ... Steering angle sensor, 17 DESCRIPTION OF SYMBOLS ... Vehicle speed sensor, 21, 41, 51 ... Microcomputer, 22 ... Drive circuit, 23 ... Gear ratio variable control calculation part, 23 ... Differential steer control calculation part, 25 ... Adder, 26 ... Rotation angle sensor, 27 ... Motor control signal Calculation unit, 29 ... torque sensor, 31 ... torque differential value calculation unit, 32, 52 ... torque differentiation control calculation unit, 33, 38, 43, 48 ... filter processing unit, 35 ... vehicle speed gain calculation unit, 36 ... multiplier 42 ... steering state determination unit, 53 ... change amount guard processing unit, 54 ... previous value holding unit, 55 ... subtractor, 56 ... guard calculation unit, θs ... steering angle, ωs ... steering speed, V ... vehicle speed, θt ... turn Rudder angle, θts ... Steer turning Angle, θta: ACT angle, θta *: ACT command angle, θgr *: Gear ratio variable command angle, θls *: Differential steer command angle, θdt *: Torque differential command angle, τ: Steering torque, dτ: Steering torque differential value , Kv: vehicle speed gain, ε, ε2: basic amount, εb: previous value, dε: difference value, Sst: steering state signal.

Claims (6)

By adding a second rudder angle of the steered wheel based on motor drive to a first rudder angle of the steered wheel that is provided in the middle of the steering transmission system between the steering wheel and the steered wheel based on a steering operation A transmission ratio variable device that varies a transmission ratio between a steering wheel and the steered wheels; and a control unit that controls an operation of the transmission ratio variable device, the control unit being based on a steering angle and a vehicle speed of the steering. A vehicle steering apparatus that calculates a control target value of the second steering angle by superimposing a compensation component based on a steering speed generated by the steering operation on a basic component,
Detecting means for detecting a steering torque input to the steering;
The control means calculates a second compensation component based on a differential value of the steering torque, and superimposes the second compensation component on the basic component together with a compensation component based on a steering speed;
A vehicle steering apparatus characterized by the above. The vehicle steering apparatus according to claim 1,
A determination unit for determining a state of the steering operation;
At least one of the steering torque detected by the detection means, the differential value thereof, and the second compensation component is subjected to low-pass filter processing,
The control means changes a cutoff frequency of the low-pass filter process according to the state of the steering operation determined by the determination means,
A vehicle steering apparatus characterized by the above. The vehicle steering apparatus according to claim 2,
When the steering operation state is incision, the control means determines the cutoff frequency of the low-pass filter processing from a value when the steering operation state is return and a value when the steering operation is maintained. Is a high value, a vehicle steering apparatus. In the steering device for vehicles according to any one of claims 1 to 3,
The control means changes the second compensation component according to the vehicle speed;
A vehicle steering apparatus characterized by the above. In the vehicle steering device according to any one of claims 1 to 4,
The vehicle steering apparatus, wherein the control means corrects the second compensation component so as to limit the amount of change of the second compensation component to a predetermined limit value or less. The vehicle steering apparatus according to claim 5,
The control means reduces the limit value of the amount of change according to an increase in the vehicle speed;
A vehicle steering apparatus characterized by the above.

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