JP6598709B2 - Power steering device - Google Patents

Description

  The present invention relates to a power steering apparatus that applies a steering assist force to a steering mechanism of a vehicle using an electric motor as a drive source.

  Conventionally, in a power steering apparatus, in order to suppress excessive assist near the steering neutral position, when the steering torque is within a predetermined range, there is a so-called dead zone in which the basic assist control amount is zero regardless of the value of the steering torque. Is provided.

  Here, there is JP 2009-208671 A (Patent Document 1) as a background art related to the problem of steering performance due to the dead zone. Patent Document 1 shows the following problems. That is, there are many cases where an actual vehicle travel path is inclined in the width direction for reasons such as improved drainage. When traveling on such a cant road, it is necessary to continue to give a small steering angle to the steering in order to suppress vehicle deflection due to the cant even when traveling straight ahead. However, the steering torque required for this is often very small, corresponding to the dead zone. For this reason, the driver must continue the minute steering operation in a state where the benefits of the power assist control cannot be obtained, and the burden is particularly great when traveling on a cant road for a long time. There is a problem of becoming something. Therefore, in patent document 1, it aims at providing the electric power steering device which can assist the steering operation for a long time effectively, and assists steering operation to a steering system by using a motor as a drive source. A steering force assisting device for applying an assist force; and a control means for controlling the operation of the steering force assisting device, wherein the control means is a basic component of the assist force applied to the steering system based on a detected steering torque. Electric power steering that corrects the steering torque used to calculate the basic component so as to increase the assist force applied to the steering system when the determined steering operation state is steering The control means calculates an accumulated time of the steering holding state, and increases the amount of correction of the steering torque as the accumulated time increases. Configuration is disclosed to be.

JP 2009-208671 A

  In Patent Document 1, when steering is performed on a cant road surface or the like in an assist dead zone, a compensation amount for increasing the assist torque is calculated based on the integrated steering torque value.

  However, Patent Document 1 does not take into consideration that the setting of the assist torque dead zone deteriorates the steering characteristics in the fine steering area. For example, when the driver shifts from steering in the left direction to steering in the right direction across the steering torque 0, if the motor command signal is 0 in the predetermined range including the steering torque 0 due to the assist torque dead zone, Even if the person continuously steers, the steering assist torque decreases in a predetermined range, and there is a possibility that a sense of incongruity may occur.

  An object of the present invention is to solve the above-described problems, improve the steering characteristics of the fine steering area due to the assist torque dead zone, and suppress the steering discomfort.

  In order to solve the above-described problems, the present invention is, as an example, a power steering device that steers a steered wheel in response to a steering operation of a steering wheel, and applies a steering force to the steering mechanism. And a control device that controls the driving of the electric motor. The control device is configured to drive the steering torque signal in a first predetermined range including a steering torque signal that is 0, which is a steering torque signal generated in the steering mechanism. The motor command signal for the steering torque signal is in a first characteristic having a characteristic that a motor command signal that is a command signal to the motor is 0, and in a second predetermined range that includes 0 and is smaller than the first predetermined range. A motor command signal calculation unit for calculating a motor command signal based on a second characteristic having a characteristic of 0, and the first characteristic or the A characteristic selecting section for selecting the second characteristic, a structure and a driving signal output unit that outputs a motor drive signal for driving and controlling the electric motor based on the motor command signal.

  ADVANTAGE OF THE INVENTION According to this invention, the power steering apparatus which improves the steering characteristic of the fine steering area by an assist torque dead zone, and suppresses a steering discomfort and its control apparatus can be provided.

It is a schematic block diagram of the power steering apparatus in an Example. It is a block diagram of the configuration of the control device in the embodiment. It is an example of basic assist MAP in an Example. It is a dead zone zero MAP example in an Example. It is an example of an assist characteristic change by dead zone zeroization MAP in an Example. It is a dead zone zeroization MAP application flowchart in an Example.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a power steering apparatus according to the present embodiment. In FIG. 1, the power steering apparatus constitutes a basic steering mechanism by a steering wheel 1, a steering shaft 2, a pinion shaft 3, and a rack shaft 4. In this steering mechanism, when the steering wheel 1 is rotated by the driver, the rotation of the steering wheel 1 is transmitted to the pinion shaft 3 via the steering shaft 2 and the rotational motion of the pinion shaft 3 is transmitted to the rack shaft. The left and right steered wheels 5 that are converted into four linear motions and connected to both ends of the rack shaft 4 are steered. That is, the rack shaft 4 is formed with rack teeth (not shown) with which the pinion shaft 3 meshes, and the rotation of the steering shaft 2 is converted into a turning operation by meshing the rack teeth with the pinion shaft 3. It consists of a mechanism.

  The steering shaft 2 is provided with a torque sensor 6 for detecting the rotation angle of the steering shaft 2 and a steering angle sensor 10. The torque sensor 6 is a sensor using a torsion bar. The control device (hereinafter also referred to as ECU) 8 is a torsion bar torque that is an output voltage of the torque sensor 6, a steering angle sensor output signal of the steering angle sensor 10, a motor rotation sensor signal of the electric motor 9, and Based on the vehicle speed obtained from the vehicle speed sensor 7, a motor command signal, which is a command signal to the electric motor 9, is calculated to control the current of the electric motor 9, and the steering assist force is applied from the electric motor 9 to the pinion shaft 3. An assist torque is applied.

  In this embodiment, an assist torque dead zone is provided in order to suppress excessive assist in the vicinity of the steering neutral in a scene that deteriorates the rudder's seat during straight traveling, etc. And That is, for example, when shifting from steering in the left direction to steering in the right direction across the steering torque 0, if the motor command signal is 0 in a so-called dead zone that is a predetermined range including the steering torque 0, the driver However, there is a possibility that the steering assist torque is reduced in a predetermined range even though the steering operation is continuously performed, and that a feeling of steering discomfort occurs. Therefore, the steering discomfort is suppressed by applying the steering assist force based on the characteristic that the dead zone is small or the dead zone is extremely close to 0 depending on the traveling situation such as whether the vehicle is traveling straight ahead or turning back.

  FIG. 2 is a configuration block diagram of the control device 8 in the present embodiment. In FIG. 2, reference numeral 21 denotes a basic assist torque calculation unit, which is based on the basic assist MAP indicating the relationship between the torsion bar torque, which is the output voltage of the torque sensor 6, and the assist torque as shown in FIG. The assist command value corresponding to is output.

  Further, reference numeral 22 denotes a dead zone zero torque calculation unit, which is shown in FIG. 4 and is based on the dead zone zero map MAP indicating the relationship between the torsional bar torque and the assist torque as the output voltage of the torque sensor 6. The assist command value corresponding to the torque is output.

  Reference numeral 23 denotes a steering torque signal obtained from the torsional torque which is an output voltage of the torque sensor 6, a vehicle speed obtained from the vehicle speed sensor 7, and a vibration of the motor rotational speed obtained from the motor rotation sensor signal of the electric motor 9. It is a vibration frequency detector for detecting the frequency.

  A dead zone variable gain calculator 25 receives the output of the vibration frequency detector 23, calculates a gain for weighting the dead zone zero torque calculated by the dead zone zero torque calculator 22, and an integrator 26 By accumulating, the dead zone zeroing torque is weighted.

  The basic assist torque from the basic assist torque calculation unit 21 and the output of the integrator 26 are added by an adder 27, and an assist command value corresponding to the assist torque as shown in FIG. 5 is output. In FIG. 5, (1) shows a case where the dead zone zeroization torque weighting is increased, and for example, the gain is set to 1.0. Further, (2) shows a case where the dead zone zeroing torque weighting is reduced, for example, an example in which the gain is set to 0.5. Further, (3) is a case where the dead zone is not zeroed, and corresponds to a case where the gain is set to zero.

  Reference numeral 24 denotes a disturbance suppression control torque calculation unit that performs disturbance suppression control that reduces the assist torque in accordance with the influence of the input from the road surface on the steering torque signal. In addition, it is desirable not to implement the dead zone zero during the disturbance suppression control. The reason is that during the disturbance suppression control, there is a possibility of being influenced by the disturbance, so that the steering stability is improved by not reacting sensitively to the disturbance input.

  As described above, in this embodiment, in order to positively implement the dead zone zero setting that is effective in improving the steering characteristics in the fine steering area, an assist torque dead zone is provided in a scene that deteriorates the rudder's seating during straight traveling. In normal reverse steering, the assist torque dead zone is set to zero. Specifically, the basic assist torque is calculated by the following formula (1).

Basic assist torque = Basic assist MAP (with dead zone) +
Zero dead zone MAP * gain (1)
As a result, when the steering torque fluctuation is a high frequency, the gain is decreased to reduce the contribution ratio of the dead zone zeroization MAP, thereby suppressing the occurrence of sensitive assistance.

  The dead zone variable gain calculation unit 25 calculates the gain by receiving the output of the vibration frequency detection unit 23. However, the gain may be calculated according to the steering torque signal or the driving situation obtained from the vehicle speed, regardless of the vibration. good.

  FIG. 6 shows a flow chart of dead zone zeroization MAP application in this embodiment. In FIG. 6, it is determined whether or not the dead zone is zeroed in step S10. If not, the dead zone is not zeroed in S13 and the process is terminated. If so, it is determined in S11 whether disturbance suppression control is being performed. If the disturbance suppression control is being performed, the dead zone is not zeroed in S13 and the process is terminated. If the disturbance suppression control is not being performed, it is determined in S12 whether the vehicle speed is equal to or less than a specified value. The process ends. If the vehicle speed is less than or equal to the specified value, the dead zone zeroing MAP is applied in S14, the dead zone zeroing MAP is weighted in S15, and a gradual change process is performed in which the weighting is gradually changed in S16. Thereby, the uncomfortable feeling of steering accompanying sudden change of the operation assist characteristic can be suppressed.

  In FIG. 2, the characteristic having the dead band and the characteristic having no dead band as shown in FIG. 5 are realized by adding the gain obtained by adding the basic assist torque and the dead band zeroing torque to the gain. However, the present invention is not limited to this. Needless to say, the respective characteristics may be simply switched. For example, in the first predetermined range including the steering torque signal of 0, the first characteristic (for example, the characteristic of (3) in FIG. 5) having the characteristic that the motor command signal for the steering torque signal is 0, and the steering torque signal are In a second characteristic (for example, the characteristic (1) or (2) in FIG. 5) having a characteristic that the motor command signal for the steering torque signal becomes zero in a second predetermined range that includes 0 and is narrower than the first predetermined range. A motor command signal calculation unit that calculates a motor command signal based on the motor command signal, a characteristic selection unit that is provided in the motor command signal calculation unit, and that selects the first characteristic or the second characteristic according to the traveling state of the vehicle; And a drive signal output unit that outputs a motor drive signal for driving and controlling the electric motor based on the above. Note that the characteristic selection unit may use only one or both of the first characteristic and the second characteristic.

  As a result, in a scene where the rudder's seat is deteriorated during straight running, etc., the assist torque characteristic is provided with a dead zone, and when the driver performs a steering operation continuously, the dead zone is steered based on a characteristic that is almost zero. By applying the assist force, it is possible to suppress a sense of discomfort in steering.

  The characteristic selecting unit may select the first characteristic and the second characteristic based on the steering torque signal. This is because the steering torque is directly connected to the steering state of the driver, so that it is suitable for characteristic selection and an appropriate steering assist force can be applied.

  The characteristic selection unit does not select the second characteristic when the frequency of the steering torque signal is equal to or higher than a predetermined frequency. This is because when the frequency of the steering torque signal is high, there is a high possibility that there is a disturbance input from the road surface. Therefore, the steering stability can be improved by not selecting the second characteristic so as not to react sensitively to the disturbance input. Can be improved.

  The characteristic selection unit selects the second characteristic when the steering torque signal is equal to or lower than the predetermined frequency and the vehicle speed is lower than the predetermined vehicle speed. Thereby, the influence of the disturbance from the road surface is small, and the uncomfortable steering feeling in the dead zone when not traveling at high speed can be suppressed.

  In addition, when the steering operation direction remains the same, for example, when the steering wheel is turned from right to left, after the steering torque signal decreases, the characteristic selection unit passes the zero state and then increases again. Select the characteristics of As a result, it is possible to suppress a sense of incongruity caused by a decrease in the steering assist amount in the dead zone when continuously steering.

  The characteristic selection unit does not select the second characteristic when the frequency of the rotational speed of the electric motor is equal to or higher than a predetermined frequency. As a result, when the frequency of the rotation speed of the electric motor is high, there is a possibility that there is a disturbance input from the road surface, so that the steering stability is not achieved by not selecting the second characteristic so that it does not react sensitively to this disturbance input. Can be improved.

  In addition, the characteristic selection unit does not select the second characteristic when the frequency of the angular velocity of the steering angle that is the rotation angle of the steering wheel is equal to or higher than a predetermined frequency. Thereby, when the frequency of the angular velocity of the steering angle is high, there is a possibility that there is a disturbance input from the road surface. Therefore, by not selecting the second characteristic so as not to react sensitively to this disturbance input, steering stability can be obtained. Can be improved.

  Further, the first characteristic and the second characteristic have a characteristic that the motor command signal matches when the steering torque signal is equal to or greater than a predetermined torque. This is because, if the steering assist characteristics are different in a region where the steering torque is relatively large, there is a possibility that it may lead to a sense of incongruity in steering, and this feeling of incongruity can be suppressed by matching both characteristics.

  Further, the first characteristic and the second characteristic have a characteristic that the motor command signal corresponding to both the steering torque signals gradually approaches as the steering torque signal increases. Thereby, it can suppress that the characteristic of the motor command signal with respect to a steering torque changes suddenly.

  In addition, the characteristic selection unit selects both the first characteristic and the second characteristic in a predetermined traveling situation. Thereby, the steering assist characteristic suitable for the driving | running | working condition can be obtained.

  Further, the characteristic selection unit changes the weighting of the first characteristic and the second characteristic in accordance with the traveling state of the vehicle. Thereby, appropriate steering assistance can be given according to various running conditions which change continuously by changing both weighting.

  The characteristic selection unit gradually changes the weighting of the first characteristic and the second characteristic in accordance with the traveling state of the vehicle. Thereby, the uncomfortable feeling of steering accompanying sudden change of the operation assist characteristic can be suppressed.

  The characteristic selection unit changes the weighting of the first characteristic and the second characteristic by changing the gain of the second characteristic. Thus, by not changing the gain of the first characteristic, which is a basic characteristic, it is possible to suppress the driver from feeling a large change in the steering assist characteristic.

  Further, the characteristic selection unit does not select the second characteristic when the vehicle speed is equal to or higher than the predetermined vehicle speed. Thereby, the steering stability during high-speed traveling can be improved.

  Needless to say, the characteristic selection unit can be read as adding the gain obtained by adding the gain to the basic assist torque and the dead zone zeroing torque as shown in FIG.

  As described above, the present embodiment is a power steering apparatus, which includes a steering mechanism that steers steered wheels in response to a steering operation of a steering wheel, an electric motor that applies a steering force to the steering mechanism, and an electric motor. A control device that controls the drive, and the control device is a motor command that is a command signal to the electric motor in response to the steering torque signal in a first predetermined range in which the steering torque signal that is a signal of the steering torque generated in the steering mechanism includes zero. A first characteristic having a characteristic that the signal is 0, and a second characteristic having a characteristic that the motor command signal for the steering torque signal is 0 in a second predetermined range that includes 0 and is narrower than the first predetermined range. A motor command signal calculation unit that calculates a motor command signal based on the characteristics, and a characteristic selection unit that selects the first characteristic or the second characteristic according to the traveling state of the vehicle; A structure having a driving signal output unit that outputs a motor drive signal for driving and controlling the electric motor based on the motor command signal.

  Further, the power steering apparatus includes a steering mechanism that steers the steered wheels in accordance with a steering operation of the steering wheel, an electric motor that applies a steering force to the steering mechanism, and a control device that controls driving of the electric motor. The control device has a characteristic that a motor command signal that is a command signal to the electric motor with respect to the steering torque signal is zero in a first predetermined range in which the steering torque signal that is a steering torque signal generated in the steering mechanism includes zero. A basic assist torque calculation unit that calculates a first motor command signal based on a characteristic of 1, and a second characteristic that the motor command signal for the steering torque signal is a value other than 0 when the steering torque signal is in a first predetermined range. A dead zone zeroing torque calculating unit that calculates the second motor command signal based on the characteristics, and a dead zone zeroing torque calculating unit according to the traveling state of the vehicle A dead zone variable gain calculation unit that calculates a gain to be multiplied by the second motor command signal; a multiplication unit that multiplies the second motor command signal from the dead zone zeroization torque calculation unit by a gain from the dead zone variable gain calculation unit; An addition unit that adds the first motor command signal from the basic assist torque calculation unit and the second motor command signal multiplied by the gain in the multiplication unit and outputs the sum as a motor command signal. Based on this, the electric motor is driven and controlled.

  Thereby, in the reverse steering where the steering torque signal crosses zero, the assist torque is smoothly connected by setting the dead zone to zero, and the fluctuation of the steering torque can be suppressed. In addition, in a state where the steering torque signal fluctuates near zero due to the influence of disturbance or the like during straight traveling or the like and the rudder's seat is deteriorated, it is possible to suppress the generation of sensitive assistance by providing a dead zone.

  Although the embodiments have been described above, the present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described.

  1: steering wheel, 2: steering shaft, 3: pinion shaft, 4: rack shaft, 5: steered wheel, 6: torque sensor, 7: vehicle speed sensor, 8: control device, 9: electric motor, 10: steering angle sensor , 21: Basic assist torque calculation unit, 22: Dead band zeroization torque calculation unit, 23: Vibration frequency detection unit, 24: Disturbance suppression control torque calculation unit, 25: Dead band variable gain calculation unit, 26: Accumulator, 27, 28 : Adder

Claims (2)

A steering mechanism for turning the steered wheels in accordance with the steering operation of the steering wheel;
An electric motor for applying a steering force to the steering mechanism;
A control device for driving and controlling the electric motor;
The control device has a characteristic that a motor command signal that is a command signal to the electric motor with respect to the steering torque signal is zero in a first predetermined range in which a steering torque signal that is a steering torque signal generated in the steering mechanism includes zero. And a second characteristic having a characteristic that the motor command signal for the steering torque signal is zero in a second predetermined range that includes 0 and is narrower than the first predetermined range. A motor command signal calculation unit for calculating the motor command signal based on
A characteristic selection unit that selects the first characteristic or the second characteristic according to a traveling state of the vehicle;
A drive signal output unit for outputting a motor drive signal for driving and controlling the electric motor based on the motor command signal;
I have a,
The power selection device, wherein the characteristic selection unit does not select the second characteristic when the frequency of the steering torque signal is equal to or higher than a predetermined frequency . A steering mechanism for turning the steered wheels in accordance with the steering operation of the steering wheel;
An electric motor for applying a steering force to the steering mechanism;
A control device for driving and controlling the electric motor;
The control device has a characteristic that a motor command signal that is a command signal to the electric motor with respect to the steering torque signal is zero in a first predetermined range in which a steering torque signal that is a steering torque signal generated in the steering mechanism includes zero. And a second characteristic having a characteristic that the motor command signal for the steering torque signal is zero in a second predetermined range that includes 0 and is narrower than the first predetermined range. A motor command signal calculation unit for calculating the motor command signal based on
A characteristic selection unit that selects the first characteristic or the second characteristic according to a traveling state of the vehicle;
A drive signal output unit for outputting a motor drive signal for driving and controlling the electric motor based on the motor command signal;
Have
The power selection device, wherein the characteristic selection unit selects the second characteristic when the steering torque signal is equal to or lower than a predetermined frequency and the vehicle speed is lower than a predetermined vehicle speed .

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