JP2013032086A - Electric power steering control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric power steering device easily achieving a natural feeling.SOLUTION: An assistance determination part 120 that determines an assist torque includes: a handle side assistance determination part 121 that determines the handle side assist torque based on a handle torque estimated value Th; and a road surface side assistance determination part 122 that determines a road surface side assist torque based on the road surface reaction force torque estimated value Tl, wherein the handle side assistance determination part 121 is assumed to be a filter, and the road surface side assistance determination part 122 is assumed to be an amplifier that multiplies the road surface reaction torque estimated value Tl by the constant.

Description

  The present invention relates to an electric power steering apparatus, and more particularly to a technique for determining an assist torque.

  The electric power steering apparatus includes a motor, and assist torque is generated by operating the motor. In order to determine the assist torque, a steering torque and a road surface reaction torque are estimated, and a command value for the assist torque is determined from the handle torque and the road surface reaction torque (for example, Patent Document 1). ).

  More specifically, in Patent Document 1, a driver's input (handle torque) is estimated by a Kalman filter having a steering torque (torsion torque) and a motor rotation angular velocity as inputs, while the estimated handle torque and the torque detected by the steering torque sensor are estimated. The difference is estimated as road reaction torque. Then, the auxiliary torque Taff is determined by multiplying the handle torque by a predetermined gain. Further, an addition value of the multiplication result obtained by multiplying the road surface reaction force torque by a predetermined gain and the multiplication result obtained by multiplying the motor rotation speed by the predetermined gain is defined as the auxiliary torque Tafb. Then, the auxiliary torque Taff and the auxiliary torque Tafb are added to obtain the final auxiliary torque Ta (target signal).

  This is based on the technical idea that the auxiliary torque corresponding to the steering (handle torque) of the driver and the auxiliary torque for suppressing the road surface reaction torque should be set independently (Patent Document 1). Paragraph 0009).

JP 2002-154450 A

  However, in Patent Document 1, since the auxiliary torque corresponding to the steering wheel torque and the auxiliary torque for suppressing the road surface reaction force torque are simply calculated by multiplying by a predetermined gain, It is not possible to generate assist torque only for a part of the information, or to convey only a part of the information from the road surface to the driver. In addition, the magnitude of the handle torque and the magnitude of the road surface reaction force torque Accordingly, the assist torque corresponding to the input torque on the side opposite to the torque cannot be adjusted. Therefore, it is not always easy to realize a natural feeling.

  The present invention has been made based on this situation, and an object of the present invention is to provide an electric power steering apparatus that can easily realize a natural feeling.

  In order to achieve the object, an invention according to claim 1 is an invention of an electric power steering apparatus having a motor that generates assist torque and an assist determination unit that determines the assist torque. The assist torque is determined based on the estimated value of the steering wheel torque estimated from the torque input from the road and the estimated road surface reaction torque estimated from the road surface. More specifically, the assist determination unit includes a steering wheel side assist determination unit that determines a steering wheel side assist torque based on the steering wheel torque estimation value, and a road surface side assist torque that determines the road surface side assist torque based on the road surface reaction force torque estimation value. An assist command value that is a command value of the assist torque based on the steering wheel side assist torque and the road surface side assist torque, and at least of the steering wheel side assist determination unit and the road surface side assist determination unit Either one includes a filter that allows some frequency components of the input torque estimation value to pass therethrough.

  Thus, in the present invention, the steering wheel side assist torque and the road surface side assist torque are independently determined based on the steering wheel torque estimated value and the road surface reaction force torque estimated value. In addition, since at least one of the steering wheel side assist determining unit and the road surface side assist determining unit includes a filter, an assist torque is generated with respect to some frequency components, or conversely, some frequency components. Therefore, it is possible to adjust so that the assist torque is not generated, so that a natural feeling can be easily realized.

  Specifically, for example, the configurations of claims 2 to 8 are conceivable. In the invention according to claim 2, the steering wheel side assist determining section includes a filter. More specifically, for example, if the filter of the steering wheel side assist determination unit is a low-pass filter that is set so as to remove a high frequency that is not intended for the driver, the driver's estimated torque value from the steering wheel torque is calculated. Since unintended high frequency components can be removed, the generated assist torque becomes smooth and smooth steering can be realized. Further, as in claim 6, a high frequency input to the handle is allowed to pass during a transition period in which the driver starts turning off the handle, while a frequency lower than the transition period input after the transition period is removed. If the high-pass filter is set to, assist based on the estimated value of the handle torque is performed only for transients such as the start of cutting, and assist delay can be suppressed. Therefore, a natural feeling can be easily realized.

  In a third aspect of the invention, the road surface side assist determining unit includes a filter. More specifically, for example, as in claim 7, the high-pass filter is set so that the high-frequency vibration from the road surface is allowed to pass through the filter of the road-side assist determining unit while the low-frequency vibration from the road surface is removed. Then, since the road surface side assist torque is determined based on the high frequency vibration from the road surface, the high frequency vibration of the road surface is canceled by the assist torque. As a result, it is possible to prevent the handle from being taken suddenly even when step-like input is made from the road surface, for example, when passing through a step. Further, if the band-pass filter is set so as to pass the vibration frequency of the road surface and the vehicle body desired by the driver as in claim 8 and to remove the low frequency and the high frequency from the frequency band, Unnecessary vibrations can be canceled while transmitting desired road surface and vehicle body vibrations. Therefore, a natural feeling can be easily realized.

  In the invention according to claim 4, the steering wheel side assist determining unit and the road surface side assist determining unit both include a filter. As described above, if any assist determination unit includes a filter, both the effects of the invention of claim 2 and the effects of the invention of claim 3 can be obtained.

  The invention according to claim 9 is also an invention of an electric power steering apparatus having a motor that generates assist torque and an assist determination unit that determines the assist torque, and the assist determination unit estimates torque input from the steering wheel. The assist torque is determined based on the estimated steering wheel torque value and the estimated road surface reaction force torque value obtained by estimating the torque input to the tire from the road surface. The assist determination unit includes a steering wheel side assist determination unit that determines the steering wheel side assist torque based on the steering wheel torque estimation value, and a road surface side assist determination unit that determines the road surface side assist torque based on the road surface reaction force torque estimation value. And an assist command value is output based on the steering wheel side assist torque and the road surface side assist torque. At least one of the steering wheel side assist determination unit and the road surface side assist determination unit includes a variable amplifier, and the amplification factor of the variable amplifier is determined based on the other estimated torque value.

  Thus, also in the present invention, the steering wheel side assist torque and the road surface side assistance torque are independently determined based on the steering wheel torque estimation value and the road surface reaction force torque estimation value. In addition, at least one of the steering wheel side assist determining unit and the road surface side assist determining unit includes a variable amplifier, and the variable amplifier determines an amplification factor based on the torque estimation value of the other side. The other assist torque is adjusted based on the value. Therefore, it becomes easy to generate assist torque in accordance with the situation, so that a natural feeling can be easily realized.

  Specifically, for example, the configurations of claims 10 to 14 are conceivable. In a tenth aspect of the present invention, the road surface side assist determining unit includes a variable amplifier, and the gain of the variable amplifier is determined based on the estimated value of the handle torque. If comprised in this way, the ratio of the road surface reaction torque transmitted to a driver will change according to a driver's input. For example, if the amplification factor is reduced as the estimated value of the steering wheel torque is increased as in the thirteenth aspect, the road surface reaction force torque is transmitted to the driver without being canceled during steering when the steering wheel torque is large, while the steering torque is small. Since the road surface reaction torque is canceled, the convergence is improved.

  In the invention described in claim 11, the steering wheel side assist determining unit includes a variable amplifier, and the variable amplifier determines the amplification factor based on the estimated road surface reaction torque. If comprised in this way, the ratio which assists driver input will change according to the input from a road surface. For example, if the amplification factor is increased as the estimated value of the road surface reaction force torque is smaller as in the fourteenth aspect, the responsiveness at the initial stage of steering when the input from the road surface is small increases, and the steering wheel returns when the input from the road surface is large. Since the ratio of the assist based on the road surface reaction torque is relatively large, the assist when the steering wheel returns is also natural.

  In the invention according to claim 12, both the steering wheel side assist determining unit and the road surface side assist determining unit include a variable amplifier, and the variable amplifier of the steering wheel side assist determining unit has an amplification factor determined based on the estimated value of the road surface reaction force torque. The variable amplifier of the road surface side assist determining unit determines the amplification factor based on the estimated handle torque value. Thus, if any assist determination unit includes a variable amplifier, and the amplification factor of these variable amplifiers is determined based on the assist value input to the other assist determination unit, the invention according to claim 10. Both the effect and the effect of the invention of claim 11 can be obtained.

1 is a schematic diagram showing an overall configuration of an electric power steering apparatus to which the present invention is applied. It is a figure which shows the detailed structure of the control apparatus 1 of FIG. It is a block diagram of the assist determination part 120 of 1st Embodiment. It is a flowchart which shows the process which the assist determination part 120 of 1st Embodiment performs. It is a block diagram of the assist determination part 120a of 2nd Embodiment. It is a block diagram of the assist determination part 120b of 3rd Embodiment. It is a block diagram of the assist determination part 120c of 4th Embodiment. It is a block diagram of the assist determination part 120d of 5th Embodiment. It is a block diagram of the assist determination part 120e of 6th Embodiment. It is a figure which shows the control apparatus 1 provided with the torque estimator 113 which estimates both steering wheel estimated value Th and road surface reaction force torque estimated value Tl.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a schematic diagram showing an overall configuration of an electric power steering apparatus to which the present invention is applied. As shown in FIG. 1, a steering shaft 3 is connected to a steering wheel (hereinafter referred to as a handle) 2, and the steering shaft 3 rotates integrally with the handle 2. A speed reduction mechanism 5 is attached to the steering shaft 3. The speed reduction mechanism 5 decelerates the rotation of the motor 6 and transmits it to the intermediate shaft 7. The motor 6 generates steering assist torque (hereinafter referred to as assist torque) that assists the driver's steering force, and is connected to the steering shaft 3 via the speed reduction mechanism 5.

  The torque sensor 4 includes a torsion bar (not shown), and the steering shaft 3 and the intermediate shaft 7 are connected by the torsion bar. When the steering shaft 3 rotates with respect to the intermediate shaft 7, the torsion bar is twisted according to the rotation. The torque sensor 4 is provided with a sensor that detects the twist, and sequentially supplies the detected twist to the control device 1.

  The end of the intermediate shaft 7 opposite to the steering shaft 3 is connected to a pinion shaft 9 of a rack and pinion gear device 8. The gear device 8 is constituted by the pinion shaft 9 and the rack shaft 10. A pair of tires 11 as left and right steered wheels are connected to both ends of the rack shaft 10 via tie rods and knuckle arms (not shown). Accordingly, when the rotational motion of the pinion shaft 9 is converted into the linear motion of the rack shaft 10, the left and right tires 11 are steered by an angle corresponding to the linear motion displacement of the rack shaft 10.

  The rotational angular velocity sensor 13 and the motor current sensor 14 sequentially detect the rotational angular velocity dThc of the motor 6 and the current Cur flowing through the motor 6, respectively, and sequentially output signals indicating the detected rotational angular velocity dThc and the motor current value Cur to the control device 1. Supply. Further, a signal indicating torque (hereinafter referred to as steering torque) Ts detected by the torque sensor 4 is also input to the control device 1. The steering torque Ts, the rotational angular speed dThc of the motor 6, and the motor current value Cur all change in detection value according to the handle torque Th and the road surface reaction torque Tl.

  Next, the configuration of the control device 1 will be described with reference to FIG. As shown in FIG. 2, the control device 1 includes a handle torque estimator 111, a road surface reaction force torque estimator 112, an assist determination unit 120, a current command value converter 130, and a current control unit 140. The steering torque estimated value 111 and the road surface reaction force torque estimator 112 all receive the steering torque Ts, the rotational angular velocity dThc of the motor 6, and the motor current value Cur from the torque sensor 4, the rotational angular velocity sensor 13, and the motor current sensor 14, respectively. Each is entered. Then, using these three input values, the handle torque estimator 111 determines the estimated value of the handle torque Th, and the road surface reaction force torque estimator 112 determines the estimated value of the road surface reaction force torque estimated value Tl. The estimation of the handle torque Th in the handle torque estimator 111 and the estimation of the road surface reaction force torque estimated value Tl in the road surface reaction force torque estimator 112 are, for example, the above three input values (steering torque Ts, rotation of the motor 6). This is performed using a relational expression in which the steering wheel torque Th or the road surface reaction force torque estimated value Tl is obtained from the angular velocity dThc and the motor current value Cur). Alternatively, a map in which the handle torque Th or the road surface reaction force torque estimated value Tl is determined from the above three input values may be used. These estimators 111 and 112 preferably have a response that quickly follows an input of a value to be estimated, and preferably has a separability that does not respond to an input other than the value to be estimated. In the following description, the estimated value of the handle torque Th and the estimated value of the road surface reaction force torque Tl are described as the handle torque estimated value Th and the road surface reaction force torque estimated value Tl.

The assist determination unit 120 calculates an assist torque command value (hereinafter referred to as an assist command value) from the handle torque estimated value Th estimated by the handle torque estimator 111 and the road surface reaction force torque estimated value Tl estimated by the road surface reaction force torque estimator 112. ) Determine Ta ^* . The detailed configuration of the assist determination unit 120 will be described later.

The current command value converter 130 converts the assist command value Ta ^* into a current command value based on a map or relational expression stored in advance. The current control unit 140 includes a known motor drive circuit such as a bridge circuit composed of four MOSFETs, for example, and the motor current value detected by the motor current sensor 14 is supplied from the current command value converter 130. Feedback control of the motor drive circuit is performed so that the current command value is obtained. The motor current sensor 14 detects the current flowing through the motor 6 by detecting the voltage across the current detection resistor provided between the motor drive circuit and the ground line.

  Next, the assist determination unit 120 will be described with reference to FIG. The assist determination unit 120 includes a steering wheel side assist determination unit 121 that determines a steering wheel side assist torque based on the steering wheel torque estimation value Th, and a road surface side assistance determination unit that determines the road surface side assist torque based on the road surface reaction force torque estimation value Tl. 122 and an adder 123 are provided.

As shown in FIG. 3, in the first embodiment, the assist command value Ta ^* is determined based on both the steering wheel torque estimated value Th and the road surface reaction force torque estimated value Tl. Here, if the assist command value Ta ^* is determined based only on the steering wheel torque estimated value Th, the assist is lost in a situation where the driver stops input (for example, when the steering wheel is returned), and as a result, the road surface The handle suddenly returns due to the reaction force. In addition, if the assist command value Ta ^* is determined based only on the road surface reaction force torque estimated value Tl, there is a time difference due to machine play until the road surface reaction force torque estimated value Tl rises after the steering wheel is turned off. As a result, the assist is delayed and a sense of viscosity is felt.

On the other hand, in the first embodiment, the assist command value Ta ^* is determined based on both the handle torque estimated value Th and the road surface reaction force torque estimated value Tl, and the steering wheel side assist torque and the road surface side assist are determined. The torque can be adjusted separately. With this configuration, various tunings can be easily performed as will be described in detail in the first embodiment and other embodiments.

  The steering wheel side assist determining unit 121 of the first embodiment is a filter, and by multiplying the steering wheel torque estimated value Th by a filter coefficient Wh determined according to the frequency, among the steering torque estimated values Th that are continuously input, Pass the component of the set frequency band. The value after passing through this filter is the steering assist torque. The steering wheel side assist torque is input to the adder 123.

On the other hand, the road surface side assist determining unit 122 of the first embodiment is an amplifier, and multiplies a road surface reaction force torque estimated value Tl by a preset constant (gain Kl) and outputs it to the adder 123. This output value is the road reaction force side assist torque. The adder 123 adds the steering wheel side assist torque and the road surface side assist torque and outputs an assist command value Ta ^* .

  Although a schematic shape of the high-pass filter is shown in the steering wheel side assist determination unit 121 in FIG. 3, the filter used here is not limited to the high-pass filter, and may be a low-pass filter or a band-pass filter. If a low-pass filter is used and its characteristic is set so as to pass the frequency of torque input to the steering wheel by the driver while removing a high frequency unintended for the driver, the high-frequency component unintended by the driver from the steering torque estimate Th. Since the generated assist torque becomes smooth, smooth steering can be realized. On the other hand, a high-pass filter is used to pass the high frequency input to the handle during the transient period when the driver starts turning the handle, while removing the frequency lower than the transient period that is input after the transient period. If set so, only a transition such as the start of cutting is assisted according to the handle torque estimated value Th, and other than the transient is assisted according to the road surface reaction force torque estimated value Tl. Therefore, it is possible to suppress the assist delay (the above-mentioned viscosity feeling) that occurs when assisting only with the road surface reaction force torque estimated value Tl. In addition, it is not restricted to a high pass filter or a low pass filter, A band pass filter or a band elimination filter can also be used. The setting of the filter pass frequency band is related to the characteristics of the driver and the vehicle, the driver's preference, and the like. Therefore, the pass frequency band of the filter is finally set based on experiments.

FIG. 4 is a flowchart illustrating processing executed by the assist determination unit 120 according to the first embodiment. First, in step S <b> 1, the steering torque Ts is read from the torque sensor 4, the rotational angular velocity dThc of the motor 6 is read from the rotational angular velocity sensor 13, and the motor current value Cur is read from the motor current sensor 14. In the subsequent step S2, the steering wheel torque estimated value Th and the road surface reaction force torque estimated value Tl are calculated using the values (Ts, dThc, Cur) read by the steering S1. The processing in these steps S1 and S2 is performed by the handle torque estimator 111 and the road surface reaction force torque estimator 112. In the subsequent step S3, an assist command value Ta ^* is calculated using the steering wheel torque estimated value Th and the road surface reaction force torque estimated value Tl obtained in step S2.

  As described above, according to the first embodiment described above, the steering wheel torque estimation value Th and the road surface reaction force torque estimation value Tl are estimated separately, and the steering wheel torque estimation value Th and the road surface reaction force torque estimation value Tl, The assist torque (the steering wheel side assist torque, the road surface side assist torque) is determined independently based on each of them. As described above, since the steering wheel side assist torque and the road surface side assist torque are determined separately, the function of assisting the driver's steering and the function of partially canceling the road surface reaction force are adjusted separately. Can be adjusted easily.

  The handle side assist determining unit 121 that determines the handle side assist torque is configured to include a filter. With this configuration, as described above, for example, a smooth steering can be realized if the filter of the steering wheel side assist determining unit 121 is a low-pass filter, and a natural feeling such as an assist delay can be suppressed if a high-pass filter is used. It can be easily realized.

(Second Embodiment)
Next, a second embodiment will be described. The second embodiment is different from the first embodiment only in the assist determination unit 120a. FIG. 5 is a configuration diagram of the assist determination unit 120a of the second embodiment. The assist determination unit 120a determines a steering wheel side assist torque based on the steering wheel torque estimated value Th, and determines a road surface side assist torque based on the road surface reaction force torque estimation value Tl. 122a and an adder 123 are provided.

  In the first embodiment described above, the steering wheel side assist determining unit 121 is a filter, while the road surface side assist determining unit 122 is an amplifier. In the second embodiment, contrary to the first embodiment, the steering wheel side assist determining unit 121 is a filter. The side assist determining unit 121a is an amplifier, and the road surface assist determining unit 122a is a filter.

  The road surface assist determination unit 122a in FIG. 5 shows a schematic shape of a high-pass filter, but the filter used here is not limited to a high-pass filter, and may be a low-pass filter, a band-pass filter, or a band elimination filter. .

  For example, if this filter is a high-pass filter and its characteristics are set to pass high-frequency vibrations from the road surface while removing low-frequency vibrations from the road surface, the road-side assist torque is increased based on the high-frequency vibrations from the road surface. Therefore, the high frequency vibration of the road surface is canceled by the assist torque, and only the low frequency vibration of the road surface is transmitted to the steering wheel. Therefore, for example, even when a step-like input such as when passing a step is from the road surface, it is possible to prevent the handle from being taken suddenly.

  In addition, if bandpass fill is used and the characteristics are set so that the frequency of vibrations of the road surface and the vehicle body desired by the driver are passed and low and high frequencies are removed from the frequency band, the characteristics of the road surface desired by the driver and Unnecessary vibration can be canceled while transmitting the vibration of the vehicle body. For example, the yaw or roll resonance frequency (for example, around 1 Hz) of the vehicle body can be set to be transmitted to the steering wheel. In this case, the movement of the vehicle body can be well understood through the steering wheel, so that steering is easy. Further, even if it is set so as to transmit the resonance frequency (for example, around 10 Hz) of the steering mechanism, the movement of the steering mechanism can be understood well, and the steering becomes easy. Further, when the tire resonance frequency (for example, around 18 Hz) is transmitted to the steering wheel, the state of the tire (cut angle and grip feeling) can be well understood during steering.

  As described above, also in the second embodiment described above, the assist torque (handle-side assist torque, road-side assist torque) is independently determined based on the handle torque estimated value Th and the road surface reaction force torque estimated value Tl. The steering wheel assist determination unit 121a that determines the assist torque is an amplifier that multiplies the steering wheel torque estimated value Th by a constant, while the road surface assist determination unit 122a that determines the road surface assist torque is a filter. With this configuration, as described above, for example, if the filter of the road surface side assist determining unit 122a is a high-pass filter, it is possible to prevent the handle from being taken suddenly. Further, if the band-pass filter is used, it is possible to easily realize a natural feeling such as unnecessary vibrations can be canceled while transmitting vibrations of the road surface and the vehicle body desired by the driver.

(Third embodiment)
Next, a third embodiment will be described. The third embodiment is different from the first and second embodiments only in the assist determination unit 120b. FIG. 6 is a configuration diagram of the assist determination unit 120b of the third embodiment. The assist determination unit 120b includes the same steering wheel side assist determination unit 121 as in the first embodiment, the same road surface side assist determination unit 122a as in the second embodiment, and an adder 123. That is, in the third embodiment, both the steering wheel side assist determining unit 121 and the road surface side assist determining unit 122a are filters. If the handle-side assist determining unit 121 has a constant gain regardless of the frequency, it is equivalent to the second embodiment, and if the road surface-side assist determining unit 122a has a constant gain regardless of the frequency, the first implementation is performed. Equivalent to form. Therefore, in the third embodiment, the effects of both the first and second embodiments can be obtained.

(Fourth embodiment)
Next, a fourth embodiment will be described. Also in the fourth embodiment, only the assist determination unit 120c is different from the first to third embodiments described so far. FIG. 7 is a configuration diagram of the assist determination unit 120c of the fourth embodiment. The assist determination unit 120c includes a steering wheel side assist determination unit 121a, a road surface side assist determination unit 122b, and an adder 123. Among these, the steering wheel side assist determining unit 121a and the adder 123 are the same as those in the first embodiment. On the other hand, the road surface side assist determination unit 122b is a variable amplifier, and the amplification factor Kl changes based on the estimated steering torque Th. Then, the road surface side reaction torque is output by amplifying the road surface reaction force torque estimation value Tl by the amplification factor Kl determined by the steering wheel torque estimation value Th.

  The amplification factor Kl may be increased or decreased in accordance with the handle torque estimated value Th. For example, assuming that the amplification factor Kl decreases as the steering wheel torque estimated value Th increases, the following effects can be obtained. That is, when the estimated handle torque value Th is large, the amplification factor Kl is small, so that the road surface reaction torque is not largely canceled by the road surface assist torque. Accordingly, the road surface reaction force torque is easily transmitted to the handle, so that the driver who holds the handle can easily understand the road surface information. Further, when the estimated steering wheel torque Th is small (for example, when the hand is released from the steering wheel or when the steering wheel is returned), the amplification factor Kl increases, so that the ratio of the road surface reaction torque Tl that is canceled by the assist torque is Increases and improves convergence.

  The degree of amplification can be variously set. For example, the output value (road surface side assist torque) is set to change with a linear function or a quadratic function with respect to the input value (road surface reaction force torque estimated value). May be. Moreover, it may be set so as to change logarithmically, and if it is changed by natural logarithm, a particularly natural feeling is obtained. Further, a map may be used instead of a function.

  As described above, according to the fourth embodiment described above, the steering wheel side assist torque is determined from the steering wheel torque estimation value Th, and the road surface side assist torque is estimated from the road surface reaction force torque estimation value Tl. Thus, since the steering wheel side assist torque and the road surface side assist torque are determined separately, it is possible to separately adjust the function of assisting the driver's steering and the function of partially canceling the road surface reaction force. This makes it easy to adjust. Further, for the road surface side assist torque, since the variable amplifier whose amplification factor Kl is determined based on the estimated steering torque Th is used, the ratio of the road surface reaction force torque transmitted to the driver changes according to the driver input. . Therefore, as described above, the road surface information is transmitted to the driver during steering, and the convergence is improved.

(Fifth embodiment)
Next, a fifth embodiment will be described. The fifth embodiment is different from the fourth embodiment only in the assist determination unit 120d. FIG. 8 is a configuration diagram of the assist determination unit 120d of the fifth embodiment. The assist determination unit 120d includes a steering wheel side assist determination unit 121b, a road surface side assist determination unit 122, and an adder 123. Among these, the road surface side assist determination part 122 and the adder 123 are the same as those of the first embodiment.

  On the other hand, the steering wheel side assist determining unit 121b is a variable amplifier, and the amplification factor Kh changes based on the road surface reaction force torque estimated value Tl. Then, the steering wheel torque estimation value Th is amplified by the amplification factor Kh determined by the road surface reaction force torque estimation value Tl, and the steering wheel side assist torque is output.

  The amplification factor Kh may be increased or decreased in accordance with the road surface reaction torque estimation value Tl. For example, it is assumed that the amplification factor Kh increases as the road surface reaction torque estimation value Tl decreases. When the road surface reaction force torque estimated value Tl is small, the amplification factor Kh is large, so that the initial steering response with a small road surface reaction torque is high. On the other hand, since the road surface reaction torque is large when the steering wheel is returned, the amplification factor Kh is small. As a result, the ratio of the road surface side assist torque in the final assist torque becomes relatively large. That is, since the assist torque when the steering wheel returns is a torque that well reflects the road surface reaction force torque, natural assist is realized.

  As described above, also in the fifth embodiment described above, the steering wheel side assist torque is determined from the steering wheel torque estimation value Th, and the road surface side assist torque is estimated from the road surface reaction force torque estimation value Tl. That is, since the steering wheel side assist torque and the road surface side assist torque are determined separately, the function of assisting the driver's steering and the function of partially canceling the road surface reaction force can be adjusted separately. Adjustment becomes easy. As for the steering wheel side assist torque, since the variable amplifier whose amplification factor Kh is determined based on the road surface reaction force torque estimated value Tl is used, the ratio of assisting the driver input changes according to the input from the road surface. Therefore, as described above, the responsiveness at the initial stage of steering becomes high, and the assist when the steering wheel returns is natural.

(Sixth embodiment)
Next, a sixth embodiment will be described. The sixth embodiment is different from the fourth and fifth embodiments only in the assist determination unit 120e. FIG. 9 is a configuration diagram of the assist determination unit 120e of the sixth embodiment. The assist determining unit 120e includes the same steering wheel side assist determining unit 121b as in the fifth embodiment, the same road surface side assist determining unit 122b as in the fourth embodiment, and an adder 123. That is, in the sixth embodiment, both the steering wheel side assist determining unit 121b and the road surface side assist determining unit 122b are variable amplifiers. Similarly to the fourth and fifth embodiments, the variable amplifier which is the steering wheel side assist determining unit 121b has an amplification factor Kh determined based on the road surface reaction force torque estimation value Tl, and the variable amplifier which is the road surface side assist determining unit 122b is An amplification factor Kl is determined based on the handle torque estimated value Th.

  Here, if the gain Kl of the steering wheel side assist determination unit 121b is set to a constant gain regardless of the road surface reaction force torque estimated value Tl, it becomes equivalent to the fourth embodiment, and the gain Kh of the road surface side assist determination unit 122b is set to the road surface reaction If a constant gain is used regardless of the estimated force torque value Tl, this is equivalent to the fifth embodiment. Therefore, in the sixth embodiment, the effects of both the fourth and fifth embodiments can be obtained.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the above-mentioned embodiment, The following embodiment is also contained in the technical scope of this invention, and also the summary other than the following is also included. Various modifications can be made without departing from the scope.

  For example, a variable amplifier having a filter function may be used as the variable amplifier in the fourth to sixth embodiments. In other words, a filter with a variable gain may be used as the variable amplifier in the fourth to sixth embodiments. In the above-described embodiment, the gain may be further changed according to the vehicle speed.

  In any of the above-described embodiments, the steering torque estimated value and the road surface reaction force torque estimated value are estimated by the separate estimators 111 and 112 in any of the embodiments. However, the present invention is not limited to this, and the two estimated values Th and Tl may be estimated by one estimator. FIG. 10 is an estimator that estimates both the handle torque estimated value Th and the road surface reaction force torque estimated value Tl with one torque estimator 113. The torque estimator 113 outputs a handle torque estimated value Th corresponding to the input handle torque when only the handle torque is input to the electric power steering apparatus and no other torque such as road reaction torque is input. In the state where only the road surface reaction force torque is inputted to the vehicle and no other torque is inputted, the road surface reaction force torque estimated value Tl corresponding to the inputted road surface reaction force torque is outputted.

1: Control device, 2: Steering wheel (handle), 3: Steering shaft, 4: Torque sensor, 5: Reduction mechanism, 6: Motor, 7: Intermediate shaft, 8: Gear device, 9: Pinion shaft, 10: Rack shaft, 11: tire, 13: rotational angular velocity sensor, 14: motor current sensor, 111: steering wheel torque estimator, 112: road surface reaction force torque estimator, 120: assist determining unit, 121: steering wheel side assist determining unit, 122 : Road surface side assist determination unit, 123: adder, 130: current command value converter, 140: current control unit

Claims (14)

A motor that generates assist torque;
Electric power having an assist determination unit that determines the assist torque based on a handle torque estimation value that estimates the torque input from the steering wheel and a road surface reaction force torque estimation value that estimates the torque input to the tire from the road surface A steering device,
The assist determination unit
A steering wheel side assist determining section for determining a steering wheel side assist torque based on the estimated steering wheel torque value; and a road surface side assist determining section for determining a road surface side assist torque based on the road surface reaction force torque estimation value. An assist command value that is a command value of the assist torque is output based on the torque and the road surface side assist torque,
At least one of the steering wheel side assist determining unit and the road surface side assist determining unit includes a filter that allows a part of frequency components of the input torque estimation value to pass therethrough. In claim 1,
The electric power steering apparatus, wherein the steering wheel side assist determining unit includes the filter. In claim 1,
The electric power steering apparatus, wherein the road surface side assist determining unit includes the filter. In claim 1,
Each of the steering wheel side assist determining unit and the road surface side assist determining unit includes the filter. In claim 2 or 4,
The electric power steering apparatus according to claim 1, wherein the filter provided in the steering wheel side assist determining unit is a low-pass filter set to remove a high frequency unintended for the driver. In claim 2 or 4,
The filter included in the steering wheel side assist determination unit passes high frequencies input to the handle during a transition period when the driver starts turning the handle, while removing frequencies lower than the transition period input after the transition period. An electric power steering device characterized by being a high-pass filter set to do. In claim 3 or 4,
The electric power steering device, wherein the filter provided in the road surface side assist determination unit is a high-pass filter set so as to pass high frequency vibrations from the road surface and remove low frequency vibrations from the road surface. In claim 3 or 4,
The filter included in the road surface side assist determination unit is a bandpass filter that is set to pass the frequency of the vibration of the road surface and the vehicle body desired by the driver and to remove lower and higher frequencies than the frequency band. An electric power steering device. A motor that generates assist torque;
Electric power having an assist determination unit that determines the assist torque based on a handle torque estimation value that estimates the torque input from the steering wheel and a road surface reaction force torque estimation value that estimates the torque input to the tire from the road surface A steering device,
The assist determination unit
A steering wheel side assist determining section for determining a steering wheel side assist torque based on the estimated steering wheel torque value; and a road surface side assist determining section for determining a road surface side assist torque based on the road surface reaction force torque estimation value. An assist command value is output based on the torque and the road surface side assist torque,
At least one of the steering wheel side assist determining unit and the road surface side assist determining unit includes a variable amplifier, and the variable amplifier has an amplification factor determined based on the estimated torque value of the other. Steering device. In claim 9,
The electric power steering apparatus according to claim 1, wherein the road surface assist determining unit includes the variable amplifier, and the variable amplifier has an amplification factor determined based on the estimated steering torque value. In claim 9,
The electric power steering apparatus according to claim 1, wherein the steering wheel side assist determination unit includes the variable amplifier, and an amplification factor is determined based on the road surface reaction force torque estimated value. In claim 9,
Both the steering wheel side assist determination unit and the road surface side assist determination unit include the variable amplifier,
The variable amplifier of the steering wheel side assist determining unit determines the amplification factor based on the road surface reaction force torque estimated value,
An electric power steering apparatus characterized in that an amplification factor of a variable amplifier of a road surface side assist determination unit is determined based on the estimated steering torque value. In claim 10 or 12,
The electric power steering apparatus according to claim 1, wherein the variable amplifier included in the road surface assist determining unit is a variable amplifier having a smaller amplification factor as the estimated value of the handle torque is larger. In claim 11 or 12,
The electric power steering apparatus characterized in that the variable amplifier provided in the steering wheel side assist determining unit is a variable amplifier in which the amplification factor increases as the estimated road reaction force torque value decreases.

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