JP2007253751A - Road surface reaction force estimation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a road surface reaction force estimation device having a disturbance observer concerning a steered wheel, and improving conventional estimation precision of road surface reaction force. <P>SOLUTION: A difference D(=d<SB>rE</SB>'(k)-f<SB>0</SB>) between a disturbance estimated value d<SB>rE</SB>' after pulse removing process and a functional value f<SB>0</SB>in step 250. A sign of a product of current speed v<SB>r</SB>(k) of a steering shaft and a parameter D is determined in step 270, and a process is moved to step 290 when it is positive and is moved to step 280 if not. Thereafter, current classification of friction force is stored in the step 280 and the step 290. For example, zero is stored in an element parameter M(k) of No. k of arrangement M as the friction force at the current point of time is static friction force in the step 280. A value of a previous road surface reaction force estimated value F<SB>rE</SB>(k-1) is adopted as a value of a current road surface reaction force estimated value F<SB>rE</SB>(k) in the following step 285. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a road surface reaction force estimation device that estimates a road surface reaction force in a steering device that steers a steered wheel of a vehicle using a motor.
This method is useful for a vehicle steering apparatus such as a power steering apparatus or a steer-by-wire system.

If a disturbance observer is used in the above road surface reaction force estimation device, the sum of the road surface reaction force F _r transmitted to the steered motor, the pulsation F _rip such as the torque ripple of the steer motor, and the friction force F _fric received by the steer motor. as the estimated value d _rE of the disturbance d _r acting on the steering motor can be obtained, thus, the estimated value F _rE desired road surface reaction force, as follows by using the estimated value d _rE of the disturbance Can be represented.
F _rE = d _rE −F _rip −F _fric (1)

For example, Non-Patent Document 1 below, a pulse F _rip due to the current detection error from the estimated value d _rE of the disturbance d _r acting on the motor, and the minute vibration suppression control techniques to remove using a torque ripple observer is disclosed Yes. In this prior art, the disturbance (d _r ) is divided into an alternating current component and a direct current component, and the alternating current component and the direct current component of the disturbance are estimated independently. According to this prior art, the disturbance is estimated. By setting the frequency of the AC component of the disturbance to a constant multiple of the electrical angular velocity of the motor, it is possible to estimate the value of the disturbance that does not include pulsations due to current detection errors.

Further, as a conventional technique for estimating the road surface reaction force F _r with high accuracy by removing the frictional force F _fric received by the motor from a reduction gear or the like from the estimated disturbance value _{dr E} , for example, the following Patent Document 1 and Patent Document There is a conventional technique described in 2. In these prior art, based on the history of the estimated disturbance value (d _rE), road surface reaction force estimated value in the previous control cycle (F _rE) estimated disturbance value in the current control cycle from (d _rE), the current control An estimation processing method that uniquely determines a road surface reaction force estimated value (F _rE ) in a cycle is adopted.
Hanamoto, 3 others, "Small vibration suppression control of brushless DC motor with periodic disturbance", 1997 IEEJ Proceedings D, Vol. 117, No. 3, p.335-341 JP-A-10-264057 JP 2003-127888 A

  When performing an estimation process using an observer, generally, if the followability of an estimated value with respect to an actual value to be estimated is set high, the estimation accuracy at that time may be lowered. For example, if the motor pulsation changes drastically, the estimated pulsation will follow the actual value sufficiently if the speed of convergence of the estimation error is not sufficiently greater than the speed of the pulsation change. Can not be made. However, if the speed of convergence of the estimation error is very large, the influence of noise on the estimated value cannot be ignored. That is, in the estimation process using the observer, there may be a trade-off relationship between the followability of the estimated value and the estimation accuracy.

  In the prior art described in Non-Patent Document 1, in order to ensure the followability of the observer that estimates pulsation, when the electrical angular velocity of the brushless DC motor is large, the real part of the eigenvalue of the observer is also set large. This is because the speed of change of pulsation is proportional to the electrical angular velocity, but according to such an observer setting, even if the followability of the observer can be ensured high, In particular, when the electrical angular velocity is large, the estimated value of pulsation is easily affected by noise. Therefore, with the above-described conventional technology, it is not always possible to remove pulsation with high accuracy.

Further, according to the prior art described in Patent Document 1 and Patent Document 2, the frictional force received from the speed reducer or the like is removed from the estimated disturbance value based only on the estimated disturbance history, so that the road surface reaction force (= disturbance) (Estimated value−friction force) may not be accurately estimated. Such a problem is that, for example, changes in the frictional force applied to the steered motor from a mechanical system such as a reduction gear actually show complex hysteresis characteristics. It occurs because it cannot be obtained.
For this reason, according to the prior arts described in Patent Document 1 and Patent Document 2, the estimated error that has been generated continues to be maintained thereafter, resulting in a large zero error (offset) in the estimated value of the road surface reaction force. there were.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to increase the estimation accuracy of the road surface reaction force in the road surface reaction force estimation device having the disturbance observer related to the steered wheels. That is.

In order to solve the above problems, the following means are effective.
That is, the first means of the present invention is a road surface reaction force estimation device that estimates a road surface reaction force in a steering device that steers a steered wheel of a vehicle using a steering motor. Based on the current, the disturbance observer has a disturbance observer that estimates the disturbance acting on the steered motor, and the notch filter uses a notch filter with a frequency that is a natural number multiple of the rotational frequency of the electrical angle of the steered motor. Pulsation removing means for removing pulsation.

However, as the angular velocity-related value, any variable parameter can be used as long as it has a numerical value that is a constant multiple of the angular velocity of the steering motor. For example, a slide of the steering shaft that drives and controls the direction of the steered wheels Speed (operation speed) or the like may be used.
The number of stages of the notch filter may be arbitrary, and the natural number may take an arbitrary value of 1 or more.
Further, the number of phases of the steering motor may be arbitrary.
In the following, 2π [radian] times the above notch frequency may be referred to as a notch angular velocity.

The second means of the present invention is to provide a lower limit value for the notch frequency of the notch filter in the first means.
However, as this lower limit value, an appropriately large value may be set within a range in which no particular problem occurs with respect to the pulsation removal processing action.

  According to a third aspect of the present invention, there is provided a road surface reaction force estimation device that estimates a road surface reaction force in a steering device that steers a steered wheel of a vehicle using a steering motor. Disturbance observer for estimating disturbance acting on the steering motor based on the current, and offset removing means for removing the zero point error of the estimated value of the disturbance based on the history of the estimated value of the disturbance and the angular velocity related value of the steering motor It is to provide.

However, the above-mentioned angular velocity-related value is a numerical value that is a constant multiple of the angular velocity of the steered motor. For example, the slide speed (operation speed) of the steered shaft that drives and controls the direction of the steered wheels is applied. Also good.
Further, the number of phases of the steering motor may be arbitrary.

  According to a fourth means of the present invention, in the first or second means described above, the zero point error of the estimated value of the disturbance is based on the estimated value of the disturbance and the history of the angular velocity related values of the steered motor. It is to provide an offset removing means for removing.

According to a fifth means of the present invention, in the offset removing means of the third or fourth means, the frictional force received by the steering motor from the mechanical system related to the steering motor is a static frictional force or a dynamic frictional force. Determination means for determining whether or not the force is a force, and should be used based on the determination result of the determination means from among a plurality of arithmetic expressions for calculating the estimated value of the disturbance from which the zero error has been removed It is to select an optimal arithmetic expression alternatively.
However, the mechanical system referred to here is, for example, a speed reducer that exerts a mechanical frictional force on the steered motor.

According to a sixth means of the present invention, in the offset removing means of the fifth means, when the conditions a, b, and d among the following five conditions a to e are simultaneously satisfied, or When a, c, and e are simultaneously established, it is determined that the frictional force has changed from a static frictional force to a dynamic frictional force.
(Condition a) It was determined that the friction force was a static friction force in the previous control cycle.
(Condition b) The estimated disturbance value in the current control cycle is larger than the sum of the estimated disturbance value and the dynamic friction force from which the zero point error in the previous control cycle has been removed.
(Condition c) The disturbance estimated value in the current control cycle is smaller than the sum of the disturbance estimated value in which the zero point error is removed in the previous control cycle and the dynamic friction force.
(Condition d) The angular velocity related value in the current control cycle is larger than a predetermined threshold value ε1 (≧ 0).
(Condition e) The angular velocity related value in the current control cycle is smaller than a predetermined threshold value ε2 (≦ 0).

However, the value of the above dynamic friction force can be determined empirically in a suitable or optimal form through experiments using actual devices such as steered wheels, steered shafts, steered motors, and reducers. it can.
The threshold value ε1 and the threshold value ε2 are safety constants that approach 0 when the measurement error of the angular velocity related value approaches 0, and may theoretically be 0. In particular, when the threshold ε1 is set to 0, the condition d is inevitably satisfied if the condition b is satisfied. In this case, if the determination process for the condition b is executed, the determination process for the condition d is performed. Can be omitted. Similarly, when the threshold value ε2 is set to 0, the condition e is inevitably satisfied if the condition c is satisfied. In this case, if the determination process for the condition c is executed, the determination process for the condition e is performed. Can be omitted.

Further, the seventh means of the present invention is the above-described fifth or sixth means for removing the offset, wherein the zero point error is removed during the period in which the friction force is determined to be a static friction force. As the value, it is to continuously adopt the estimated disturbance value from which the zero point error is removed, which is calculated in the control cycle in which the friction force is finally determined as the dynamic friction force.
By the above means of the present invention, the above-mentioned problem can be effectively or rationally solved.

According to the first means of the present invention, since the pulsation caused by the current detection error is removed by the notch filter, it is not necessary to estimate or remove the pulsation in the disturbance observer. For this reason, the disturbance observer according to the present invention can employ a configuration that is hardly affected by noise regardless of the electrical angular velocity of the steered motor. That is, it is not necessary to increase the speed of convergence of the disturbance estimation error in accordance with the increase in the electrical angular velocity of the steered motor.
Therefore, according to the first means of the present invention, the estimated value of the disturbance can be made less susceptible to noise, and the pulsation term is also effectively removed, so the road surface reaction force is estimated with high accuracy. can do.

Further, according to the second means of the present invention, the notch frequency does not fall below a predetermined threshold value, so that the pulsation removal processing performance when the angular speed of the steering motor is large is sufficiently ensured, and The deterioration phenomenon of the transient response of the filtering process when the angular velocity is small can be effectively and prevented beforehand.
That is, if the notch frequency is too low, when the angular speed of the steered motor is small, the transient response deterioration phenomenon of the filtering process is caused. However, according to the second means of the present invention, the steering is performed by the above threshold setting. When the angular velocity of the motor is small, the filtering process is substantially omitted, and thus the possibility of such a transient response deterioration phenomenon occurring is inevitably eliminated. In such a case, since the influence of pulsation is small, it can be practically ignored, and thus the filtering process can be omitted.

  Further, according to the third or fourth means of the present invention, the history of the angular velocity related value of the steered motor can be used in the frictional force removing process, and thereby the estimation according to the hysteresis characteristic is performed. Since the processing can be realized, it is possible to configure a road surface reaction force estimation device with a small offset error caused by the frictional force received from the mechanical system.

  More specifically, for example, according to the fifth means of the present invention, the optimum arithmetic expression to be used is alternatively selected based on the determination result of the determination means, so that each friction state By preparing a plurality of appropriate arithmetic expressions according to each, the zero point error can be accurately removed. Therefore, according to the fifth means of the present invention, it is possible to effectively prevent the zero point error of the road surface reaction force estimated value from expanding due to the change of the frictional force.

  According to the sixth means of the present invention, the timing at which the frictional force changes from the static frictional force to the dynamic frictional force can be determined more accurately than before by using the angular velocity related value of the steering motor. Therefore, it is possible to effectively suppress an increase in the offset error of the estimated road surface reaction force due to the change in the frictional force.

  Further, the static friction force is not uniquely determined only by the rotation direction of the steering motor and the estimated disturbance value. However, if the seventh means of the present invention is used, the static friction force immediately before and immediately after the static friction force starts to act. It is assumed that the road surface reaction force does not change, and the estimation process is continued as it is. For this reason, according to the 7th means of this invention, it can suppress effectively that the offset error of a road surface reaction force estimated value expands.

  In carrying out the present invention, it is more desirable to estimate the road surface reaction force by using both the offset removing means and the pulsation removing means, but in that case, it was obtained from a disturbance observer. It is more desirable that the pulsation removing means is applied to the estimated disturbance value before the offset removing means. In this case, since the offset removal means can process the estimated value of the disturbance from which the pulsation has been effectively removed, it is possible to more reliably eliminate the possibility that a determination error will occur during the offset removal processing. .

In the above-described offset removing means, a desired offset removing process may be configured according to the following design guidelines (1) to (5).
(1) The frictional force is removed based on the history of the angular velocity related value and disturbance estimated value of the steered motor.
(2) When static friction is acting, the estimated disturbance value from which the offset at the previous time (previous control cycle) is removed is maintained as it is.
(3) When dynamic friction is acting, the frictional force is removed based on the sign of the angular velocity related value at the current time and the estimated disturbance value at the current time.
(4) Whether the frictional force acting on the steered motor has changed from static friction to kinetic friction depends on the sign of the angular velocity related value at the current time, the estimated disturbance value at the current time, and the estimated disturbance value from which the offset at the previous time has been removed. Judgment based on.
(5) Whether the frictional force acting on the steered motor has changed from dynamic friction to static friction is determined based on the sign change of the angular velocity related value.

Hereinafter, the present invention will be described based on specific examples.
However, the embodiments of the present invention are not limited to the following examples.

  FIG. 1 shows a logical configuration diagram of the steer-by-wire system according to the first embodiment. This steer-by-wire system electrically realizes a steering mechanism (1-7) having a handle 1 operated by a driver, a steering mechanism (8-13) for turning the steered wheels 13, and an interlocking operation thereof. The control device 1000 and the like are configured.

More specifically, the torque sensor 2 of the steering mechanism to detect the steering torque T _h the driver on the steering wheel 1, the rotation angle sensor 5 detects the rotational angle theta _h of the reaction force motor 4, the current sensor 6 A current I _h fed from the motor drive circuit 7 to the reaction force motor 4 is detected. However, the reaction force motor 4 and the handle 1 are interlocked by the speed reducer 3, so that the rotation angle Θ _h of the reaction force motor 4 is proportional to the rotation angle of the handle 1. These detected values are input to a control device 1000 having an A / D conversion device.

On the other hand, the steering motor 10 of the steering mechanism is a three-phase brushless DC motor, and its rotation angle Θ _r is detected by a rotation angle sensor 11. The phase currents I _v and I _u fed from the motor drive circuit 8 to the steered motor 10 are detected by the current sensor 9, and these detected values are also sent to the control device 1000 including the A / D converter. Entered.

FIG. 2 shows a control block diagram of the control apparatus 1000 described above.
The steered motor 10 is physically three-phase controlled by detecting the U-phase current I _u and the V-phase current I _v with the current sensor 9, but the UVW / dq conversion processing unit 1800, current control Using the unit 1600 and the dq / UVW conversion processing unit 1900, the current is logically controlled in the dq coordinate space.
The road surface reaction force estimation unit 100 is a part corresponding to the road surface reaction force estimation device of the present invention, and the sliding speed in the axial direction of the turning shaft 12 input from the turning speed calculation unit (hereinafter referred to as the turning speed). v _r ) and a q-axis current I _q output from the UVW / dq conversion processing unit 1800, a desired road surface reaction force estimated value F _rE is calculated.

FIG. 3 shows a control block diagram of the road surface reaction force estimation unit 100. The road surface reaction force estimating unit 100 includes a disturbance estimating unit (disturbance observer 110), a pulsation removing unit 120, and an offset removing unit 130.
Hereinafter, the configuration and operation of each of these units will be described in order.

First, the disturbance observer 110 in FIG. 4 (disturbance estimating means), for example as shown in the figure 4 and the above formula (1), disturbance d _r a road surface reaction force F _r acting on the steering motor 10 And the pulsating force F _rip caused by the current detection error and the frictional force F _fric due to the friction of the speed reducer, and the estimated disturbance value _{dr E} which is the estimated value _based on the rack speed v _r and the q-axis current I _q Calculated.
Here, s is a complex frequency, K _tr is a torque constant of the steered motor 10, G _r is its gain, and M _r is an inertia coefficient of the steered motor 10. The filter characteristics of the low-pass filter 111 can be optimally determined by tuning the parameter ω _or and the parameter ξ _or .

Further, the estimated disturbance value _drE 'in FIG. 3 is a value obtained by subjecting the estimated disturbance value _drE , which is the output value of the disturbance observer 110, to the following filtering process. That is, the pulsation removing unit 120 in FIG. 3 removes the pulsating power F _rip from the estimated disturbance value _{dr E} using the notch filter F _n (s, ω _n ) whose transfer function is defined by the following equation (Equation 1). To do. Here, s is a complex frequency, and ξ ₁ and ξ ₂ are positive parameters that determine the filter characteristics.

For example, by using this notch filter F _n (s, ω _n ) in two stages, the following series two-stage notch filter can be configured.
(First stage)
_{ω n = Ω1 = max (C} , ω e) (C is a predetermined constant)
(Second stage)
ω _n = Ω 2 = max (C, 2ω _e )

Here, ω _e (≡αv _r ; α is a proportional constant) and 2ω _e (= 2αv _r ) are used in a normal brushless DC motor as described in Non-Patent Document 1 described above. This is because pulsations of 1 and 2 times the electrical angular velocity ω _e are often dominant.
The above-mentioned max function is a function for selecting the not smaller among the two arguments, of providing such a lower limit value C with respect to the notch angular velocity omega _n is the notch frequency omega _n is too small This is because the transient response of the filter output d _rE ′ becomes slow, which is not preferable. Conversely, when the electrical angular velocity ω _e is small, the pulse power F _rip generated in the motor is also small, and in this case, it can be said that there is no need to perform filtering.

The above filtering processing (pulsation removing unit 120) eliminates the pulsation term F _{rip in} the above equation (1), and thus the disturbance estimated value (filter output d _rE ′) is expressed by the following equation (2). In addition, it can be represented by the sum of the estimated value F _rE of the road surface reaction force and the frictional force F _fric acting on the steered motor 10.
(Disturbance estimate d _rE ′)
d _rE ′ = F _rE + F _fric (2)

FIG. 4 illustrates a control block diagram of the disturbance observer 110. The offset removing unit 130 in FIG. 4 removes the frictional force F _fric acting on the steered motor 10 from the estimated disturbance value _drE ′ output from the pulsation removing unit 120, _{thereby obtaining} the equation (2). To obtain the desired road surface reaction force estimated value F _rE . In this frictional force removal process, the relationship between the road surface reaction force estimated value _FrE and the disturbance estimated value _drE 'that appears when dynamic frictional force is acting on the steered motor 10 (the graph of FIG. 5). ).

( _Relationship between F _rE and d _rE ′)
That is, when dynamic friction is acting,
If v _r > 0, then d _rE ′ = f ₁ (F _rE ),
If v _r <0, then d _rE ′ = f ₂ (F _rE ) (3)

For example, the function f ₁ in the graph of FIG. 5 has a _form of d _rE ′ = F _rE + d ₀ (d ₀ is a positive constant) when F _rE ≧ 0, and d when F _rE <0. _rE ′ = aF _rE + d ₀ (0 <a <1). The function f ₂ has a point-symmetric shape obtained by rotating the function f ₁ around the origin by 180 °.

FIG. 6 illustrates a control processing procedure for realizing the offset removing unit 130 with software using this graph. In the control processing procedure of the offset removing unit 130, as an initial state of the processing, the initial value of the control variable k is 0, M (0) = 0 (: during static friction action), v _r (0) = 0, and F _{Assume rE} (0) = 0. Here, the control variable k indicates the time discretized in the width of the control cycle of this process.

First, in the first step 205 of this procedure, the value of the control variable k is incremented by one. In the next step 210, the sign of the speed v _r (k) of the steered shaft at the current time (current control cycle) is determined. As a result, if v _r (k)> 0, the process proceeds to step 220; otherwise, the process proceeds to step 230.

Next, in step 220 and step 230, as shown in the following equation (4), the road surface reaction force of this time is obtained by using the inverse functions f ₁ ^-1 and f ₂ ^-1 of the functions f ₁ and f ₂ in FIG. The value of the estimated F _rE (k) is provisionally.
(Provision of F _rE (k))
F _rE (k) = f ₁ ⁻¹ (d _rE ′ (k)) (step 220),
F _rE (k) = f ₂ ⁻¹ (d _rE ′ (k)) (Step 230) (4)

Next, in step 225 and step 235, as shown in the following equation (5), the functions f ₁ and f ₂ of FIG. 5 are used and the static friction force is applied in the previous control cycle. As a preparation for power subsequent processing (step 250), a function value f ₀ of the road surface reaction force estimation F _rE (k−1) is obtained. As can be seen from the following equation (5), FIG. 5 and the like, this function value f ₀ is the “estimated disturbance value from which the zero point error in the previous control cycle has been removed” in the above (condition b) and (condition c). It has a numerical value equivalent to "the sum of dynamic friction forces".
(Function value f ₀ )
f ₀ = f ₁ (F _rE (k−1)) (step 225),
f ₀ = f ₂ (F _rE (k−1)) (Step 235), (5)

Next, in step 240, the type of friction force in the previous control cycle is determined. If M (k-1) = 0 (: static friction), the process proceeds to step 250, where M (k-1) = 1 ( : Dynamic friction), the process proceeds to step 260.
Next, in step 250, it obtains the disturbance estimate d _rE 'difference between the function value _{f 0 D (= d rE'} (k) -f 0). On the other hand, at step 260, instead of this, the previous speed V _r (k−1) of the steered shaft is substituted for this variable D.

Next, in step 270, the sign of the product of the speed v _r (k) of the current turning shaft and the variable D is determined. If it is positive, the process proceeds to step 290, and if not, the process proceeds to step 280. . However, here, it is sufficient that only the sign of the product v _r (k) · D can be determined, and therefore it is not always necessary to obtain the value of the product v _r (k) · D. Here, since it is assumed that the above-described threshold values ε1 and ε2 are both 0, the magnitude determination with respect to the threshold values ε1 and ε2 of the absolute value of the angular velocity related value v _r (k) of the steered motor 10 is as follows. not going.

Next, in step 280 and step 290, the type of the friction force at this time is stored. For example, in step 280, since the friction force at the current time is a static friction force, 0 is stored in the k-th element variable M (k) of the array M. In the next step 285, the previous road surface reaction force estimated value F _rE (k−1) is adopted as the current road surface reaction force estimated value F _rE (k).

And if the above processing procedure is followed, the following processing results can be obtained.
(1) When static friction is acting at the previous time k-1 (when M (k-1) = 0)
a) When d _rE ′ (k)> f ₁ (F _rE (k−1)) and v _r (k)> 0, the friction force acting on the steered motor is changed from static friction force to dynamic friction force in step 270. It is determined that it has changed, and an output result of the following expression is obtained.
F _rE (k) = f ₁ ⁻¹ (d _rE ′ (k))

b) When d _rE ′ (k) <f ₂ (F _rE (k−1)) and v _r (k) <0, the friction force acting on the steered motor is changed from static friction force to dynamic friction force in step 270. It is determined that it has changed, and an output result of the following expression is obtained.
F _rE (k) = f ₂ ⁻¹ (d _rE ′ (k))

c) Other cases It is determined in step 270 that static friction is acting on the steered motor, and the output result of the following equation is obtained by the action of step 285.
F _rE (k) = F _rE (k−1)

(2) When dynamic friction is acting at the previous time k-1 (when M (k-1) = 1)
a) When v _r (k−1)> 0 and v _r (k)> 0 It is determined in step 270 that dynamic friction is acting on the steered motor, and an output result of the following equation is obtained.
F _rE (k) = f ₁ ⁻¹ (d _rE ′ (k))

b) When v _r (k−1) <0 and v _r (k) <0, it is determined in step 270 that dynamic friction is acting on the steered motor, and an output result of the following equation is obtained.
F _rE (k) = f ₂ ⁻¹ (d _rE ′ (k))

c) Other cases It is determined in step 270 that the frictional force acting on the steered motor has changed from dynamic frictional force to static frictional force, and the output result of the following equation is obtained by the action of step 285.
F _rE (k) = F _rE (k−1)

  By estimating the road surface reaction force as described above, it is possible to calculate a road surface reaction force estimation value with a small pulsation due to the current detection error, and a road surface reaction force with a small offset error due to the friction of the reducer. An estimate can be obtained.

In FIG. 7, the control block diagram of the reaction force motor control part of the control apparatus 1000 is illustrated. The target torque calculating section 1100, based on the calculated road surface reaction force estimated value F _rE as described above, to determine a target value T _h ^* of the steering torque, for example, using the table information such as a map.
Torque control section 1200, based on the detected steering torque T _h and the target value T _h ^*, calculates the target value u _h ^* of the torque reaction force motor to be output. This target value u _h ^* can be obtained by, for example, proportional control as illustrated in FIG.
The current control unit 1300 calculates a target voltage V _h ^* to be output by the motor drive circuit 7 by proportional-integral control using the current I _h supplied to the reaction force motor and the target value u _h ^*. To do.
The road surface reaction force estimated value F _rE can be effectively used when the output of the reaction motor is optimally controlled according to the road surface reaction force, for example.

  The steering motor 10 is logically controlled in the dq coordinate space as described above. This current control is also performed using, for example, well-known PDI control or PI control in FIGS. 2 and 8. It can be configured as illustrated.

[Other variations]
The embodiment of the present invention is not limited to the above-described embodiment, and other modifications as exemplified below may be made. Even with such modifications and applications, the effects of the present invention can be obtained based on the functions of the present invention.
(Modification 1)
For example, in the first embodiment, a three-phase brushless DC motor is used as the steering motor 10, but the apparatus 100 does not include the pulsation removing unit (for example, the pulsation removing unit 120 in FIG. 3) of the present invention. For this reason, the steered motor 10 is not necessarily a brushless DC motor. That is, even when a brushed DC motor or the like is used as the steering motor, an offset removal effect similar to the above is obtained by the action of the offset removal means (eg, the offset removal unit 130 in FIG. 6) of the present invention. be able to.

  In the above embodiment, the present invention is applied to the steer-by-wire system. However, the present invention is not limited to the steer-by-wire system. It can also be used.

1 is a logical configuration diagram of a steer-by-wire system according to Embodiment 1. FIG. The control block diagram of the control apparatus 1000. The control block diagram of the road surface reaction force estimation part 100. FIG. Control block diagram of disturbance observer 110. The graph which shows the relationship between road surface reaction force estimated value _FrE and disturbance estimated value _drE '. 5 is a flowchart illustrating a control processing procedure for realizing an offset removal unit 130. The control block diagram of the reaction force motor control part of the control apparatus 1000. The control block diagram of the steering motor control part of the control apparatus 1000.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10: Steering motor 100: Road surface reaction force estimation apparatus 110: Disturbance observer 120: Pulsation removal part 130: Offset removal part 1000: Control apparatus

Claims (7)

In a road surface reaction force estimation device that estimates a road surface reaction force in a steering device that steers a steered wheel of a vehicle using a steering motor,
A disturbance observer that estimates a disturbance acting on the steering motor based on the angular velocity related value and the phase current of the steering motor;
A road surface comprising pulsation removing means for removing pulsation of the estimated value of the disturbance using a notch filter having a notch frequency of a frequency that is a natural number multiple of the rotational frequency of the electrical angle of the steering motor. Reaction force estimation device. The notch filter is
The road surface reaction force estimation apparatus according to claim 1, wherein the road surface reaction force estimation apparatus has a lower limit value related to the notch frequency. In a road surface reaction force estimation device that estimates a road surface reaction force in a steering device that steers a steered wheel of a vehicle using a steering motor,
Based on the angular velocity related value and phase current of the steering motor,
A disturbance observer for estimating a disturbance acting on the steering motor;
Based on the estimated value of the disturbance and the history of angular velocity related values of the steering motor,
A road surface reaction force estimation apparatus, comprising: offset removal means for removing a zero error included in the estimated value of the disturbance. Based on the estimated value of the disturbance and the history of angular velocity related values of the steering motor,
The road surface reaction force estimation apparatus according to claim 1, further comprising an offset removing unit that removes a zero point error included in the estimated value of the disturbance. The offset removing means includes
Determination means for determining whether the frictional force received by the steering motor from the mechanical system related to the steering motor is a static frictional force or a dynamic frictional force;
Alternatively selecting an optimum arithmetic expression to be used from a plurality of arithmetic expressions for calculating the estimated value of the disturbance from which the zero point error has been removed, based on a determination result of the determination means. The road surface reaction force estimation device according to claim 3 or 4, characterized by the above. When it is determined that the frictional force is a static frictional force in the previous control cycle,
The offset removing means includes
If the estimated value of the disturbance in the current control cycle is larger than the sum of the estimated disturbance value from which the zero point error has been removed in the previous control cycle and the dynamic friction force, and the angular velocity related value in the current control cycle Is greater than a predetermined threshold ε1 (≧ 0), or
If the estimated value of the disturbance in the current control cycle is smaller than the sum of the estimated disturbance value from which the zero point error has been removed and the dynamic friction force in the previous control cycle, and the angular velocity related value in the current control cycle Is smaller than a predetermined threshold ε2 (≦ 0),
The road surface reaction force estimation device according to claim 5, wherein the frictional force is determined to have changed from a static frictional force to a dynamic frictional force. The offset removing means includes
During the period when the frictional force is determined to be a static frictional force, as a disturbance estimated value from which the zero point error has been removed, it was calculated in a control cycle in which the frictional force was finally determined as a dynamic frictional force. The road surface reaction force estimation apparatus according to claim 5 or 6, wherein the disturbance estimated value from which the zero point error has been removed is continuously employed.

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