JP2008254522A - Steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering device capable of attaining early detection of wheel unbalance and avoiding deterioration of steering feeling caused by the wheel unbalance. <P>SOLUTION: A micro-computer 41 is provided with a specific frequency extraction part 51 for extracting a specific frequency component corresponding to wheel unbalance generated on respective turned wheel from steering torque τ input as a signal indicating the state of the steering system; and a wheel unbalance determination part 52 for determining generation of the wheel unbalance when power spectrum Sp, i.e., an actual value of the specific frequency component is a predetermined threshold value Sth or higher at non-braking. Further, when generation of the wheel unbalance is determined in the wheel unbalance determination part 52, ECU 23 lights-on a warning lamp 55 for warning generation of the wheel unbalance provided in a cabin (not shown). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a steering device.

Conventionally, in a steering apparatus for a vehicle, suppression of vibration generated in the steering system has been the most important issue. That is, the steering feeling is greatly impaired by the driver feeling the vibration of the steering system or the noise generated by the vibration. For this reason, in many steering devices, for example, an electric power steering device (EPS) using a motor as a drive source, a vibration-proof structure is provided so that vibration generated by the motor is not transmitted to the steering system (for example, Patent Document 1) Or various countermeasures, such as reducing motor vibration itself by suppressing generation | occurrence | production of a torque ripple (for example, patent document 2), are taken.
JP 2006-27537 A JP 2006-131179 A JP 2004-224129 A

  However, the vibrations generated in the steering system are not only generated in the steering system and the configuration for applying the assist force to the steering system, but also in the configuration on the steered wheels connected to the steering system. There can be. Specifically, when an error occurs in the wheel balance of the steered wheels, that is, when wheel unbalance occurs, vibrations generated thereby are transmitted from the steering system to the steering. And a driver | operator will sense this vibration, and there exists a possibility that a steering feeling may deteriorate.

  For example, in EPS, the vibration caused by such a configuration on the steered wheel side is suppressed to some extent by strengthening so-called torque inertia compensation control (see, for example, Patent Document 3) based on the differential value of the steering torque. Is possible. However, the strengthening of the torque inertia compensation control (increase in the torque differential control amount) results in an excessive rise of the assist torque, and accordingly, the steering feeling during normal operation deteriorates (so-called “disengagement feeling at the start of turning”). Or there is an adverse effect of causing instability of control (vibration). For this reason, there is a limit to the vibration suppression measures by such control, and the fundamental solution is that the passenger feels the vibration transmitted from the steering as a deterioration of the steering feeling, and the cause of this is the wheel unbalance. The actual situation is that there is nothing but to adjust the foil balance.

  The present invention has been made in order to solve the above-described problems, and its purpose is to detect wheel unbalance early and to avoid deterioration of steering feeling due to the wheel unbalance. The object is to provide a steering device.

  In order to solve the above-mentioned problems, the invention according to claim 1 is characterized in that a detection means for generating a signal indicating the state of the steering system and a wheel unbalance generated in the steered wheels from the signal indicating the state of the steering system. The specific frequency extraction means capable of extracting a specific frequency component corresponding to, and the foil unbalance occurs when the effective value of the extracted specific frequency component is not less than a predetermined threshold value during non-braking. And a warning means for warning the wheel unbalance.

  According to the said structure, before the vibration resulting from wheel unbalance becomes obvious as deterioration of steering feeling, the said wheel unbalance can be detected at an early stage and it can notify a passenger. Then, by prompting the wheel balance to be adjusted promptly, it is possible to avoid the deterioration of the steering feeling due to the wheel unbalance.

  According to a second aspect of the present invention, the determination means determines that the wheel unbalance has occurred when an effective value of the specific frequency component is equal to or greater than a predetermined threshold value and is in a straight traveling state. Is the gist.

  That is, in a state where the steering angle is generated, vibrations due to factors other than wheel unbalance occur. Therefore, by adding that the vehicle is in a straight traveling state to the determination condition as in the above configuration, it is possible to detect the foil unbalance with higher accuracy.

  According to a third aspect of the present invention, the determination means determines that the wheel unbalance has occurred when an effective value of the specific frequency component is equal to or greater than a predetermined threshold and is in a predetermined vehicle speed range. The gist is to do.

  That is, the amplitude of vibration generated in the steering system depends on the vibration characteristics of the suspension that supports the steered wheels, and is amplified in a specific vehicle speed region where resonance occurs in the suspension. Therefore, by setting a predetermined vehicle speed region so as to correspond to this specific vehicle speed region, particularly a region where vibration due to wheel unbalance increases, and adding to the determination condition whether or not it is within the vehicle speed region, More accurate foil unbalance detection can be performed.

  According to a fourth aspect of the present invention, there is provided a steering force assisting device capable of applying an assist force for assisting a steering operation to a steering system using a motor as a drive source, and motor control based on a signal indicating a state of the steering system. Control means for controlling the operation of the steering force assisting device, wherein the motor control includes compensation control based on a differential value of steering torque which is a signal indicating a state of the steering system, and the control means includes The gist is to enhance the compensation control based on the differential value of the steering torque when it is determined that a balance has occurred.

  According to the above configuration, until the wheel balance is adjusted and the wheel unbalance is eliminated, the vibration caused by the wheel unbalance is suppressed by the compensation control (torque inertia compensation control), and a good steering fee is achieved. The ring can be maintained. And by enhancing torque inertia compensation only when wheel unbalance has occurred, the steering feeling deteriorates during normal operation due to excessive rise of the assist torque (so-called “disengagement feeling” at the start of turning). ) Or instability (vibration) of the control can be suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, the steering apparatus which can aim at the early detection of wheel unbalance and can avoid the deterioration of the steering feeling resulting from the said wheel unbalance can be provided.

Hereinafter, an embodiment in which the present invention is embodied in a column type electric power steering apparatus (EPS) will be described with reference to the drawings.
As shown in FIG. 1, in the electric power steering apparatus (EPS) 1 of the present embodiment, a steering shaft 3 to which a steering 2 is fixed is connected to a rack shaft 5 via a rack and pinion mechanism 4. The rotation of the steering shaft 3 accompanying the operation is converted into a reciprocating linear motion of the rack shaft 5 by the rack and pinion mechanism 4. Specifically, the steering shaft 3 of the present embodiment is formed by connecting a column shaft 8, an intermediate shaft 9, and a pinion shaft 10 via universal joints 7a and 7b, and the rack and pinion mechanism 4 includes: The pinion teeth 10a formed at one end of the pinion shaft 10 are engaged with the rack teeth 5a on the rack shaft 5 side. Then, the reciprocating linear motion of the rack shaft 5 accompanying the rotation of the steering shaft 3 is transmitted to a knuckle (not shown) via tie rods 11 connected to both ends of the rack shaft 5, so that the steering angle of the steered wheels 12 is increased. That is, the traveling direction of the vehicle is changed.

  The EPS 1 according to the present embodiment controls the operation of the EPS actuator 22 by providing an assist force for assisting the steering operation to the steering system by rotating the steering shaft 3 using the motor 21 as a drive source. ECU23 which performs.

  More specifically, the EPS actuator 22 of the present embodiment is configured as a so-called column-type EPS actuator that applies assist force to the column shaft 8, and the motor 21 that is a drive source is connected to the column shaft via the speed reduction mechanism 24. 8 is drive-coupled. In this embodiment, the speed reduction mechanism 24 is configured by meshing a reduction gear 25 provided so as not to rotate relative to the column shaft 8 and a motor gear 26 provided so as not to rotate relative to the motor shaft 21a. Has been. In the present embodiment, a so-called worm and wheel is employed for the speed reduction mechanism 24. The EPS actuator 22 as a steering force assisting device decelerates the rotation of the motor 21 that is a driving source by the speed reduction mechanism 24 and transmits it to the column shaft 8, thereby giving the motor torque as an assist force to the steering system. It is configured as follows.

  On the other hand, the ECU 23 as control means supplies driving power to the motor 21 that is a driving source of the EPS actuator 22. And it is comprised so that rotation of the motor 21, ie, the action | operation of the EPS actuator 22, may be controlled through the supply of the drive electric power.

  More specifically, the ECU 23 is connected to a torque sensor 31 provided on the column shaft 8. In this embodiment, the column shaft 8 is formed by connecting a first shaft 8 a on the steering 2 side and a second shaft 8 b on the intermediate shaft 9 (pinion shaft 10) side via a torsion bar 33. Yes. The torque sensor 31 includes a torsion bar 33 and a pair of angle sensors 34a and 34b (resolvers) provided at both ends of the torsion bar 33 (the end of the first shaft 8a and the end of the second shaft 8b). It is configured.

  That is, the torque sensor 31 of the present embodiment is configured as a twin resolver type torque sensor, and the ECU 23 detects the rotation angle (steering angle θs) of the first shaft 8a by the first angle sensor 34a. The rotation angle (pinion angle θp) of the second shaft 8b is detected by the second angle sensor 34b. Then, the steering torque τ is detected based on the difference between the rotation angles detected by the both angle sensors 34a and 34b, that is, the twist angle of the torsion bar 33.

  In the present embodiment, the ECU 23 receives the vehicle speed V detected by the vehicle speed sensor 35 and a brake signal Sbk indicating whether or not a brake operation is performed. Then, the ECU 23 determines a target assist force to be applied to the steering system based on the vehicle state quantities detected by these sensors, and drives the motor 21 to generate the target assist force in the EPS actuator 22. Execute power supply.

Next, an aspect of assist control in the EPS of the present embodiment will be described.
As shown in FIG. 2, the ECU 23 includes a microcomputer 41 that outputs a motor control signal, and a drive circuit 42 that supplies drive power to the motor 21 that is a drive source of the EPS actuator 22 based on the motor control signal. Configured.

  In the present embodiment, the ECU 23 is connected with a current sensor 43 for detecting the actual current value I supplied to the motor 21 and a rotation angle sensor 44 (see FIG. 1) for detecting the motor rotation angle θm. ing. Then, the microcomputer 41 controls the drive circuit 42 based on each vehicle state quantity and the actual current value I of the motor 21 and the motor rotation angle θm detected based on the output signals of the current sensor 43 and the rotation angle sensor 44. A motor control signal to be output is generated.

  More specifically, the microcomputer 41 is calculated by a current command value calculation unit 45 that calculates a target value of assist force to be applied to the steering system, that is, a current command value Iq * corresponding to the target assist force, and a current command value calculation unit 45. And a motor control signal output unit 46 for outputting a motor control signal based on the current command value Iq *.

  The current command value calculation unit 45 of this embodiment includes a basic assist control unit 47 that calculates a basic assist control amount Ias *, which is a basic control component of the target assist force, and a differential value ( And a torque inertia compensation control unit 48 for calculating a torque inertia compensation amount Iti * based on the steering torque differential value dτ).

  In this embodiment, the steering torque τ and the vehicle speed V are input to the basic assist control unit 47. Then, based on the steering torque τ and the vehicle speed V, the basic assist control unit 47 calculates a larger basic assist control amount Ias * as the steering torque τ increases and the vehicle speed V decreases.

  On the other hand, in addition to the steering torque differential value dτ, the vehicle speed V is input to the torque inertia compensation control unit 48 of the present embodiment. The torque inertia compensation control unit 48 executes torque inertia compensation control based on these state quantities. “Torque inertia compensation control” is control that compensates for the effects of EPS inertia, such as motors and actuators, that is, “feeling of catching (following delay)” at the time of “start of cutting” and “end of cutting” in steering operation. This is control for suppressing the “flow feeling (overshoot)”. The torque inertia compensation control has an effect of suppressing vibration generated in the steering system.

  Specifically, as shown in FIG. 3, the torque inertia compensation control unit 48 of the present embodiment includes a map 48a in which the steering torque differential value dτ and the basic compensation amount εti are associated, the vehicle speed V, the interpolation coefficient A, and the like. Is associated with a map 48b. In the map 48a, the basic compensation amount εti is a value that increases the basic assist control amount Ias * (absolute value) calculated by the basic assist control unit 47 as the absolute value of the input steering torque differential value dτ increases. It is set to become. Further, in the map 48b, the interpolation coefficient A is set so as to increase as the vehicle speed V increases in the low vehicle speed region, and to decrease as the vehicle speed increases in the high vehicle speed region. Then, the torque inertia compensation controller 48 calculates the torque inertia compensation amount Iti * by multiplying the basic compensation amount εti and the interpolation coefficient A obtained by referring to these maps 48a and 48b.

  As shown in FIG. 2, the basic assist control amount Ias * calculated in the basic assist control unit 47 and the torque inertia compensation amount Iti * calculated in the torque inertia compensation control unit 48 are input to the adder 49. The current command value calculation unit 45 calculates the current command value Iq * as the target assist force by superimposing the torque inertia compensation amount Iti * on the basic assist control amount Ias * in the adder 49.

  The current command value Iq * output from the current command value calculation unit 45 is output to the motor control signal output unit 46 together with the actual current value I detected by the current sensor 43 and the motor rotation angle θm detected by the rotation angle sensor 44. Entered. The motor control signal output unit 46 calculates a motor control signal by executing feedback control so that the actual current value I follows the current command value Iq * corresponding to the target assist force.

  Specifically, in the present embodiment, a brushless motor that rotates by supplying three-phase (U, V, W) driving power is used as the motor 21. Then, the motor control signal output unit 46 converts the phase current values (Iu, Iv, Iw) of the motor 21 detected as the actual current value I into d, q axis current values in the d / q coordinate system (d / q The current feedback control is performed by performing conversion.

  That is, the current command value Iq * is input to the motor control signal output unit 46 as a q-axis current command value, and the motor control signal output unit 46 outputs the phase current based on the motor rotation angle θm detected by the rotation angle sensor 44. The value (Iu, Iv, Iw) is d / q converted. Further, the motor control signal output unit 46 calculates the d and q axis voltage command values based on the d and q axis current values and the q axis current command value. Then, the phase voltage command values (Vu *, Vv *, Vw *) are calculated by performing d / q inverse conversion on the d and q axis voltage command values, and a motor control signal is generated based on the phase voltage command values. To do.

  In the ECU 23 of the present embodiment, the microcomputer 41 outputs the motor control signal generated as described above to the drive circuit 42, and the drive circuit 42 supplies the three-phase drive power based on the motor control signal to the motor 21. Is configured to control the operation of the EPS actuator 22.

(Foil unbalance detection)
Next, the foil unbalance detection function which EPS of this embodiment has is demonstrated.
As shown in FIG. 2, in the present embodiment, the microcomputer 41 configuring the ECU 23 is provided with a specific frequency extraction unit 51 that can extract a specific frequency component from an input signal. In the present embodiment, the specific frequency extraction unit 51 is input with a steering torque τ as a signal indicating the state of the steering system, and the specific frequency extraction unit 51 receives the input steering torque. A specific frequency component corresponding to the vibration generated in the steering system is extracted from τ. Specifically, the specific frequency extraction unit 51 extracts, from the input steering torque τ, a frequency component corresponding to the vibration caused by the wheel balance imbalance occurring in each steered wheel 12, that is, the wheel unbalance. The effective value is output as the power spectrum Sp.

  More specifically, as shown in the flowchart of FIG. 4, the specific frequency extraction unit 51 first performs a band pass filter process on the input steering torque τ (step 101), and specifies the wheel unbalance. A frequency component of 14 to 16 Hz is extracted as a frequency component (step 102). Next, the specific frequency extraction unit 51 obtains an effective value of the frequency component extracted in step 102 by RMS (Root Means square) calculation (step 103). Then, low-pass filter processing is executed (step 104), and the value after the low-pass filter processing is output as a power spectrum Sp (step 105).

  Further, as shown in FIG. 2, the microcomputer 41 of the present embodiment is provided with a wheel unbalance determining unit 52, and the power spectrum Sp output from the specific frequency extracting unit 51 is the brake sensor 53 (FIG. 1). And the brake signal Sbk output by the reference) is input to the wheel unbalance determination unit 52. Then, the wheel unbalance determining unit 52, when not braking, has a wheel unbalance in the steered wheels 12 when the power spectrum Sp, which is the effective value of the specific frequency component, is equal to or greater than a predetermined threshold value Sth. Is determined.

  Further, in the present embodiment, a warning lamp 55 is provided in the passenger compartment (not shown) for warning the vehicle occupant that wheel unbalance has occurred. The ECU 23 is provided with a drive circuit 56 for lighting the warning lamp 55, and the microcomputer 41 outputs the wheel unbalance determining unit 52 when the wheel unbalance is detected as described above. A signal indicating that the wheel unbalance is detected, that is, a detection signal Str is output to the drive circuit 56. The drive circuit 56 is configured to supply drive power to turn on the warning lamp 55 based on the input of the detection signal Str.

Next, the process procedure of the wheel unbalance detection in the wheel unbalance determination unit will be described.
As shown in the flowchart of FIG. 5, the wheel unbalance determination unit 52 first determines whether or not the brake signal Sbk that is input is “off” (step 201). If the brake signal Sbk is “off” (step 201: YES), it is determined whether or not the input power spectrum Sp is equal to or greater than a predetermined threshold value Sth (step 202).

  Here, in the present embodiment, the steering angle θs is input to the wheel unbalance determination unit 52, and when it is determined in step 202 that the power spectrum Sp is equal to or greater than a predetermined threshold value Sth ( Sp ≧ Sth, Step 202: YES), the wheel unbalance determination unit 52 determines whether or not the absolute value of the steering angle θs is equal to or smaller than a predetermined threshold θth (Step 203). In this case, the steering angle in the vicinity of the steering neutral is set as the threshold value θth. That is, the wheel unbalance determining unit 52 of the present embodiment determines whether or not the vehicle is in a straight traveling state in step 203. When the absolute value of the steering angle θs is equal to or smaller than the predetermined threshold θth (| θs | ≧ θth, step 203: YES), it is determined that a wheel unbalance has occurred (step 204) and is output. The warning lamp 55 is turned on based on the detection signal Str.

  If any of the determination conditions of steps 201 to 203 is not satisfied (step 201: NO, step 202: NO, or step 203: NO), the wheel unbalance determination unit 52 performs the process of step 204. Do not execute.

As described above, according to the present embodiment, the following operations and effects can be obtained.
(1) The microcomputer 41 extracts a specific frequency component corresponding to the wheel unbalance generated in each steered wheel 12 from the steering torque τ input as a signal indicating the state of the steering system, A wheel unbalance determining unit 52 that determines that a wheel unbalance has occurred when the power spectrum Sp, which is the effective value of the specific frequency component, is greater than or equal to a predetermined threshold value Sth during non-braking. When the wheel unbalance determining unit 52 determines that the wheel unbalance has occurred, the ECU 23 warns that the wheel unbalance provided in the passenger compartment (not shown) has occurred. The warning lamp 55 is turned on.

  According to the above configuration, the occurrence of the wheel unbalance can be detected and notified to the passenger at an early stage before the vibration caused by the wheel unbalance becomes apparent as the deterioration of the steering feeling. Then, by prompting the wheel balance to be adjusted promptly, it is possible to avoid the deterioration of the steering feeling due to the wheel unbalance.

  (2) When the wheel unbalance determining unit 52 determines that the power spectrum Sp is equal to or greater than the predetermined threshold value Sth (Sp ≧ Sth, Step 202: YES), the absolute value of the steering angle θs is subsequently determined as steering. It is determined whether or not it is equal to or less than a predetermined threshold value θth in the vicinity of neutrality (step 203). That is, it is determined whether or not the vehicle is traveling straight. When the absolute value of the steering angle θs is equal to or smaller than the predetermined threshold θth (| θs | ≧ θth, Step 203: YES), it is determined that a wheel unbalance has occurred (Step 204).

  That is, in a state where the steering angle is generated, vibrations due to factors other than wheel unbalance occur. Therefore, by adding that the vehicle is in a straight traveling state to the determination condition as in the above configuration, it is possible to detect the foil unbalance with higher accuracy.

In addition, you may change this embodiment as follows.
In the present embodiment, the present invention is embodied in a so-called column type EPS 1, but applied to a so-called rack type that applies assist force to the rack shaft 5, or a so-called pinion type EPS that applies assist force to the pinion shaft 10. May be.

  In the present embodiment, the specific frequency extraction unit 51 as the specific frequency extraction unit and the wheel unbalance determination unit 52 as the determination unit are provided in the ECU 23 (the microcomputer 41). However, the configuration is not limited to this, and the specific frequency extraction unit and the determination unit may be provided separately from the ECU 23.

  In the present embodiment, the warning lamp 55 is provided in the passenger compartment (not shown) as warning means. However, the warning means includes warning sounds and voices in addition to those notified through the passenger's vision. Etc., that is, a notification made through the auditory sense of the passenger may be used.

  In this embodiment, the steering torque τ detected by the torque sensor 31 is used as a signal indicating the state of the steering system. However, the present invention is not limited to this, and a pinion indicating the rotation angle of the pinion shaft 10 constituting the steering system. You may use angle (theta) p and steering angle (theta) s (steering wheel angle) which is a rotation angle by the side of the steering wheel 2. Needless to say, the position of the pinion angle θp, the steering angle θs, and the steering torque τ in the frequency analysis is not an instantaneous value but a continuous signal.

  In the present embodiment, the present invention is embodied in EPS. However, the present invention is not limited to this, and the present invention is not limited to this, as long as it has a detection means that can generate a signal indicating the state of the steering system (steering torque, steering angle, etc.) such as a torque sensor or a steering angle sensor. The power steering device may be embodied as a non-assist type steering device that does not have a steering force assisting device for applying assist force to the steering system.

  In the present embodiment, the wheel unbalance occurs when the power spectrum Sp, which is the effective value of the specific frequency component, is equal to or greater than the predetermined threshold value Sth and the vehicle is traveling straight (see FIG. 5, step 203: YES). (See FIG. 5). However, the present invention is not limited to this, and the straight traveling condition (step 203) may be abolished.

  In the present embodiment, the brake determination (see FIG. 5, step 201) is performed based on the brake signal Sbk, but may be performed based on acceleration (deceleration) in the vehicle deceleration direction.

  In the present embodiment, the straight-running state determination (see FIG. 5, step 203) is performed based on whether or not the absolute value of the steering angle θs is equal to or less than a predetermined threshold θth. However, the present invention is not limited to this, and other state quantities such as a steering torque τ, a steering speed, or a yaw rate may be used instead of the steering angle θs for the straight traveling state determination.

  Furthermore, as shown in the flowchart of FIG. 6, a condition determination (step 304) is added as to whether or not the vehicle speed V at the time of wheel unbalance determination is within a predetermined vehicle speed region (V1 ≦ V ≦ V2), When the vehicle speed V is within the specific vehicle speed range (step 304), it may be determined that a wheel unbalance has occurred (step 305). Note that the processing in steps 301 to 303 in the flowchart of FIG. 6 is the same as the processing in steps 201 to 203 in the flowchart of FIG.

  That is, the amplitude of vibration generated in the steering system depends on the vibration characteristics of the suspension that supports the steered wheels, and is amplified in a specific vehicle speed region where resonance occurs in the suspension. Accordingly, the predetermined vehicle speed region (V1 ≦ V ≦ V2) is set in this specific vehicle speed region, particularly in a region where vibration due to wheel unbalance increases, and it is determined whether or not the vehicle is within the vehicle speed region. By doing so, it becomes possible to detect foil unbalance with higher accuracy.

  In the present embodiment, the present invention is embodied in EPS 1 that performs compensation control (torque inertia compensation control) based on the differential value of steering torque τ (steering torque differential value dτ). You may apply to what does not perform the compensation control based on the derivative value of torque (tau).

  In addition, as in the EPS 1 of the present embodiment, in the motor control, in the case where the compensation control (torque inertia compensation control) based on the differential value of the steering torque τ is executed, it is determined that the wheel unbalance has occurred. In this case, the compensation control may be strengthened.

  For example, as shown in FIG. 7, a correction coefficient α for increasing the torque inertia compensation amount Iti * is output to the current command value calculation unit 65 based on the input of the detection signal Str indicating that the wheel unbalance has been detected. A correction coefficient calculation unit 70 is provided. The current command value calculation unit 65 calculates the current command value Iq * based on the torque inertia compensation amount Iti ** corrected by the correction coefficient α (Iti ** = Iti * × α). do it.

  In this case, the correction coefficient α is preferably set to a value that increases the torque inertia compensation amount Iti * as the power spectrum Sp that is the effective value of the specific frequency component increases. Specifically, the power spectrum Sp output from the specific frequency extraction unit 51 is input to the correction coefficient calculation unit 70, and the power spectrum Sp and the correction coefficient α are associated with the correction coefficient calculation unit 70. A map 70a is provided (see FIG. 8). In the map 70a, the correction coefficient α is set so as to increase as the power spectrum Sp increases. Then, the correction coefficient calculation unit 70 may calculate the correction coefficient α by referring to the input power spectrum Sp to this map 70a.

  According to the above configuration, until the wheel balance is adjusted and the wheel unbalance is eliminated, the vibration caused by the wheel unbalance is suppressed by the torque inertia compensation to maintain a good steering feeling. Can do. Further, by strengthening the torque inertia compensation only when the wheel unbalance occurs, it is possible to suppress the occurrence of the adverse effects of the torque inertia compensation as described above.

The schematic block diagram of an electric power steering device (EPS). The control block diagram of EPS. The control block diagram of a torque inertia compensation control part. The flowchart which shows the process sequence of a specific frequency extraction part. The flowchart which shows the process sequence of foil unbalance detection. The flowchart which shows the process sequence of the wheel unbalance detection of another example. The control block diagram of another example EPS. A map that associates the power spectrum with correction factors.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Electric power steering device (EPS), 2 ... Steering, 3 ... Steering shaft, 8 ... Column shaft, 9 ... Intermediate shaft, 10 ... Pinion shaft, 12 ... Steering wheel, 21 ... Motor, 22 ... EPS actuator, 23 ... ECU, 31 ... Torque sensor, 35 ... Vehicle speed sensor, 41 ... Microcomputer, 42 ... Drive circuit, 45, 65 ... Current command value calculation unit, 46 ... Motor control signal output unit, 47 ... Basic assist control unit, 48 ... Torque Inertia compensation control unit, 51 ... specific frequency extraction unit, 52 ... wheel unbalance determination unit, 53 ... brake sensor, 55 ... warning lamp, Iq * ... current command value, Ias * ... basic assist control amount, Iti *, Iti * *: Torque inertia compensation amount, θp: Pinion angle, θs: Steering angle, θth: Threshold value, τ: Steering torque, dτ: Steering torque derivative , V ... vehicle speed, Sp ... power spectrum, Sth ... threshold, Sbk ... brake signal.

Claims (4)

Detecting means for generating a signal indicating the state of the steering system;
Specific frequency extraction means capable of extracting a specific frequency component corresponding to the wheel unbalance generated in the steered wheels from the signal indicating the state of the steering system;
A determination means for determining that the wheel unbalance has occurred when an effective value of the extracted specific frequency component is equal to or greater than a predetermined threshold value during non-braking;
And a warning means for warning the wheel unbalance. The steering apparatus according to claim 1, wherein
The determination means determines that the wheel unbalance has occurred when an effective value of the specific frequency component is equal to or greater than a predetermined threshold and is in a straight traveling state;
A steering apparatus characterized by the above. In the steering device according to claim 1 or 2,
The determination means determines that the wheel unbalance has occurred when an effective value of the specific frequency component is equal to or greater than a predetermined threshold and is in a predetermined vehicle speed range;
A steering apparatus characterized by the above. In the steering device according to any one of claims 1 to 3,
The operation of the steering force assisting device is controlled by a steering force assisting device capable of applying an assisting force for assisting a steering operation to the steering system using a motor as a drive source, and motor control based on a signal indicating the state of the steering system Control means,
The motor control includes compensation control based on a differential value of steering torque, which is a signal indicating the state of the steering system,
The steering device according to claim 1, wherein when it is determined that the wheel unbalance has occurred, the control unit enhances compensation control based on a differential value of the steering torque.

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