JP2004284569A - Operation reaction force generation controlling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an operation reaction force generation controlling device capable of transmitting road surface state and other necessary information to a driver with small torque, and of improving steering feeling without friction feeling in an operation system by rationally estimating and eliminating friction generated when an operation input means is operated. <P>SOLUTION: The operation reaction force generation controlling device is provided with a torque sensor 6 for detecting driver steering torque Ts of a driver on a steering wheel 1, and a rotary encoder 4 for detecting a steering shaft rotation angle α caused by the operation of the driver. A steering reaction force controller 8 has a friction estimating section for estimating the friction of the actuator section based on the detected driver steering torque Ts, the detected steering shaft rotation angle α and the applied control input, and a friction compensating section for changing the control input to eliminate the estimated friction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention belongs to the technical field of an operation reaction force generation control device that generates a steering reaction force transmitted to a driver by steer-by-wire, electric power steering, or the like.
[0002]
[Prior art]
Conventionally, there has been proposed an electric power steering system in which a range in which the steering angular velocity is small is determined to be stationary, and dither is added to a control current to convert static friction into dynamic friction, thereby causing vibration ( For example, see Patent Document 1). Further, the steering torque is differentiated, and it is determined that the driver has started steering based on the magnitude of the differentiated value (edge), and the static friction force is estimated from the magnitude and compensated (for example, see Patent Reference 2). In addition, in order to reduce the Coulomb friction, it is customary to add an offset current corresponding to friction removal in advance by looking at the direction of the steering speed.
[0003]
[Patent Document 1]
JP-A-2002-46632
[Patent Document 2]
JP-A-2000-103349
[0004]
[Problems to be solved by the invention]
However, in the prior art, the friction torque is not rationally estimated and removed by feedback, but is determined in a feed-forward manner based on the conditions of the vehicle (steering speed and direction), and the influence of the friction is determined. I was trying to remove it.
[0005]
For this reason, there is a problem that the driver will feel uncomfortable if the rules are not followed. For example, if measures are taken to add dither where the steering angular velocity is small, dither must be applied in most of the driving conditions, and it is feared that the vibration will be transmitted to the driver. There is a problem that it is not preferable from the viewpoint of this.
[0006]
In addition, even if the edge of the steering torque is extracted, friction compensation is likely to be performed because the torque is differentiated. There was a problem of being late.
[0007]
Furthermore, when the offset current is switched in the direction of the steering speed, the friction torque frequently changes the sign during a minute steering operation, and the hunting of the friction compensation current is transmitted to the driver. There was also.
[0008]
All of the above problems have been caused by trying to compensate for friction in a feed-forward manner based on uncertain detection information.
[0009]
The present invention has been made in view of the above problems, and rationally estimates and removes friction when operating the operation input means, so that the driver can use a small amount of torque to reduce road surface conditions and other necessary conditions. It is an object of the present invention to provide an operation reaction force generation control device that can transmit information and that can improve steering feeling without friction in an operation system.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention,
An operation input means for the driver to input a command value for changing the direction of the vehicle, an actuator for adjusting an operation reaction force applied to the operation input means, and a control means for controlling a generated force of the actuator. In the operation reaction force generation control device,
Operating force detecting means for detecting an operating force on the driver's operation input means,
Operation state amount detection means for detecting displacement or speed of the operation input means caused by the operation of the driver,
The control means,
Based on the detected operation force, the detected displacement or speed of the operation input unit, and the applied control input, a friction estimation unit that estimates the friction of the actuator unit,
A friction compensator that changes the control input so as to remove the estimated friction,
It is characterized by having.
[0011]
Here, the `` friction estimating unit '' has, for example, a model driven by a control input and a driver's operation force, and when an operation state amount by displacement or speed of the operation input means is passed through the inverse characteristic of the model. Based on the difference between the estimated value of the sum of the control input and the operation input that is obtained and the total value of the actual control input and the operation input, the force input as the disturbance is used as the estimated friction value.
[0012]
【The invention's effect】
Therefore, in the operation reaction force generation control device of the present invention, the friction at the time of operating the operation input means is rationally estimated and removed, so that the driver can use a small amount of torque to give the road surface condition and other necessary information. The effect of being able to convey is created. In addition, the effect of improving the steering feeling of the vehicle can be expected by eliminating the frictional feeling of the operation system.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment for realizing the operation reaction force generation control device of the present invention will be described based on first to fourth examples shown in the drawings.
[0014]
(First embodiment)
First, the configuration will be described.
The first embodiment describes a case where the operation reaction force generation control device of the present invention is applied to a steering reaction force generation unit of a steer-by-wire.
[0015]
FIG. 1 is an overall system diagram showing the operation reaction force generation control device of the first embodiment. In FIG. 1, 1 is a steering wheel (operation input means), 2 is a reduction gear, 3 is a motor (actuator), 4 is a rotary encoder (operation state quantity detection means), 5 is a steering shaft, and 6 is a torque sensor (operation force). Detecting means), 7 is a vehicle speed sensor (vehicle speed detecting means), and 8 is a steering reaction force controller (control means).
[0016]
The steering wheel 1 is an operation input unit for a driver to input a command value for changing the direction of the vehicle. The operation input means may be a lever such as a joystick.
[0017]
The reduction gear 2 is a reduction mechanism that reduces the rotation of the motor 3 and provides the rotation to the steering shaft 5. Although the reduction gear 2 is a spur gear in FIG. 1, it may be constituted by a worm or the like if toothing noise or the like is a concern.
[0018]
The motor 3 is an actuator that adjusts an operation reaction force of the steering wheel 1. As the motor 3, a DC servo motor or a brushless motor may be used. If sufficient torque can be obtained, the motor shaft may be directly used as the shaft of the steering wheel 1 without having the reduction gear 2.
[0019]
The rotary encoder 4 is an operation state amount detection unit that indirectly detects a displacement of the steering wheel 1 caused by a driver's operation based on a rotation angle of a motor shaft. Note that the rotary encoder 4 can determine the rotation angle, but a tachogenerator may be attached instead of the rotary encoder 4 to detect the rotation speed. Furthermore, although the rotation of the motor shaft is detected, a rotary encoder may be similarly attached to the position of the steering shaft 5. However, since the rotation of the motor shaft is detected, the angle can be detected more finely by detecting the rotation of the motor shaft in terms of angular resolution. Therefore, the position where the rotation of the motor shaft is detected is more preferable.
[0020]
The torque sensor 6 is provided at the position of the steering shaft 5 and detects an operation force (driver steering torque) on the steering wheel 1 of the driver. Note that the torque sensor 6 may have a general configuration used for electric power steering.
[0021]
The steering reaction force controller 8 inputs rotation angle information from the rotary encoder 4, driver steering torque information from the torque sensor 6, and vehicle speed information from the vehicle speed sensor 7, and outputs a signal to the motor 3 based on these information. The applied current is calculated, and the motor 3 is driven by the applied current. It is assumed that a motor drive circuit (not shown) of the steering reaction force controller 7 can supply current stably. For example, it is assumed that the current is servo-controlled so as to be hardly affected by the back electromotive force.
[0022]
Next, the operation will be described.
[Effect of friction estimation at angle detection]
FIG. 2 is a block diagram of the operation reaction force generation control of the first embodiment for estimating the friction torque based on the steering shaft rotation angle α.
The signal of the torque sensor 6 is used as the driver steering torque Ts (known disturbance).
Friction torque Tf (unknown disturbance)
Motor inertia moment Js (However, this is converted into a steering shaft and includes the inertia moment of the steering wheel 1)
Motor torque constant Kt (However, converted to steering shaft)
Motor generated torque Tm = Kt · i (However, converted to steering shaft)
Motor applied current i
Steering shaft rotation angle α
Steering shaft rotation angular acceleration α ''
Then, the equation of motion is as follows.
Js · α ″ = Ts + Tm + Tf (1)
In the state where disturbances Ts and Tf are not added to the plant,
Js · α ″ = Kt · i (2)
Therefore, when expressed by a transfer function, s is expressed as a Laplace operator as follows.
α / i = Kt / (Js · s ² ) = P (s) (3)
The frequency band of disturbance elimination is defined as fc (Hz), and ωc = 2πfc (rad / s).
A low-pass filter for disturbance rejection,
H (s) = ωc ² / (S + ωc) ² … (4)
And In this state, if a controller is configured around the control target (plant) as shown in FIG. 2, the friction torque estimated from the portion A in FIG. 2 can be obtained by converting it into a current value. Feedback to input current. Thus, friction is removed.
[0023]
A current limiter is provided in the feedback path. For example, when the friction to be compensated is at most 1 Nm, the limiter may be set at a current value = 1 / Kt (A) corresponding to 1 Nm. .
[0024]
The reason for providing the limiter also includes the following effects. For example, when ωc = 2πfc (rad / s) is set high, the friction torque may be excessively estimated as high-frequency noise due to noise on the control system. As a result, the actuator is driven by the friction compensation current, and a jerky feeling is transmitted to the driver. However, saturation of the current by inserting a limiter also has an effect of preventing such a feeling of strangeness.
[0025]
[Operation reaction force generation control action]
Conventionally, feedforward has been actively used as a method for removing friction. However, the following problem occurs in the friction removal by the feed forward.
[0026]
For example, suppose that there is 1 Nm of friction in the plant, and a current of 1 A is applied to compensate for it. However, when the friction is actually only 0.2 Nm, the torque of 0.8 Nm is transmitted to the driver, which leads to a feeling of steering discomfort. As described above, there is a problem that it is not possible to flexibly cope with the case where the characteristics of the assumed target (plant) and the actual plant are different.
[0027]
Then, it is natural to think that it is sufficient to add feedback for controlling while exploring the state of the plant. However, there is no invention that eliminates friction by feedback. The problem with friction is static friction. The friction when the driver is steering is so-called dynamic friction, which may be rather preferable because it also contributes to damping of the steering system. However, when the steering is started from the steering-holding state, static friction occurs. If the friction is large, the driver feels that the vehicle is just "jammed". That is, friction at an extremely low frequency (steady state) must be removed.
[0028]
What can be considered at this time is integral control which is generally used to eliminate a steady-state error in control. Since the integral control works so that the integral value of the error becomes zero, it should be effective for removing friction in a steady state. As described above, since the integral control can remove the steady-state deviation, in the case of position control or the like, if a steady-state deviation is to occur, a force is gradually applied in a direction to remove the deviation. Here, the term “slowly” is used because the dynamic characteristics of the entire closed-loop system are generally reduced when the integral control is greatly effective, and divergence occurs in extreme cases. Therefore, generally, the integration constant is not set so large. That is, the steady-state deviation is generally gradually removed and gradually approaches the target value. Therefore, in such a method, it is impossible to remove the friction at the same time as the start of the steering operation, and the feeling of being stuck at the start of the steering operation is kept as it is, and while the steering wheel is being turned, the lightness gradually decreases. As described above, since the expected effect cannot be obtained by the method of simply adding the feedback of the integration, the friction removal by the feedback has not been performed until now.
[0029]
The disturbance observer of the present invention is one integral control. However, the difference from the general integration is that the frequency domain in which disturbance is removed can be set by the filter H (s). The point of the present invention is to set the cutoff frequency of the filter H (s) high. By doing so, it is theoretically possible to estimate and remove not only the steady-state deviation but also the high-frequency disturbance.
The fact that "theoretically" is written is that it is generally difficult to estimate a high-frequency disturbance because it is necessary to correctly understand the characteristics of a plant up to a high frequency. In other words, when estimation is made up to the high-frequency disturbance, an erroneous disturbance estimation value of a high frequency is obtained, and if the friction is removed based on the estimated value, the steering system rattles at a high frequency, resulting in a steering system that is strangely jerky to the driver. Therefore, in the present invention, a method is used in which a limiter is provided for the disturbance estimation value so that the above-mentioned jerky feeling is not felt while estimating the high-frequency disturbance, and the disturbance estimation value is saturated at a constant value. By doing so, the disturbance estimation value rises at the same time as the start of steering and saturates at a certain value.
[0030]
Next, effects will be described.
In the operation reaction force generation control device of the first embodiment, the following effects can be obtained.
[0031]
(1) A steering wheel 1 for the driver to input a command value for changing the direction of the vehicle, a motor 3 for adjusting the operation reaction force applied to the steering wheel 1, and a steering reaction for controlling the generated force of the motor 3 In the operation reaction force generation control device including the force controller 8, a torque sensor 6 for detecting a driver steering torque Ts of the driver with respect to the steering wheel 1, and a steering shaft rotation angle α generated by the operation of the driver are detected. A rotary encoder 4 is provided, and the steering reaction force controller 8 controls the motor 3 and the reduction gear 2 based on the detected driver steering torque Ts, the detected steering shaft rotation angle α, and the added control input. A friction estimator that estimates the friction of the actuator section and removes the estimated friction And a friction compensation unit that changes the control input so that the friction caused when the operation input means is operated is rationally estimated and removed, so that the driver can use a small torque to reduce the road surface condition and other necessary conditions. Information can be transmitted, and the steering system can be improved without a frictional feeling in the operation system.
[0032]
That is, the friction when the operation input means represented by the steering wheel 1 is operated is rationally estimated and eliminated, so that the road surface condition and other necessary information can be transmitted to the driver with a small torque. The effect is born. For example, if such a mechanism is not attached to the reaction force generating portion of the steer-by-wire, a large torque must be generated to return the steering wheel (steering wheel 1) to the neutral position. For this reason, even during normal steering, those torques may become an obstacle, and there is a possibility that the restoring torque with respect to the steering wheel operation may increase. In general, the absence of a frictional feeling in the operation system results in a "clean" feeling, which is preferable. Therefore, an effect of improving the steering feeling of the vehicle can be expected.
[0033]
(2) The friction estimation unit has a model P (s) driven by a control input and a driver's operation force, and is obtained when the steering shaft rotation angle α is passed through the inverse characteristic of the model P (s). Given the difference between the estimated value of the sum of the control input and the operation input and the sum of the actual control input and the operation input, the force input as the disturbance is used as the estimated friction value, so that a reasonable friction estimation configuration is provided. Can be.
[0034]
In other words, instead of the conventional feed-forward control such as "it will be this", "the driver is actually steering with the detected torque, and the detected energy is applied to the actuator. Therefore, the handle should move this much according to the model, if not, because the movement of the actuator is constrained by disturbances such as friction. " By constructing the diagram (FIG. 2) and estimating the disturbance by feedback, necessary and sufficient friction estimation is performed. Therefore, it is possible to remove the friction torque without causing strange strangeness such as different timing.
[0035]
(3) The friction compensating unit sets an upper limit (current limiter) for the current corresponding to the estimated friction value, and removes the friction below the current limiter. That is, the friction compensating unit determines the upper limit value of the friction and sets the upper limit of the friction. Even if the estimated value is obtained, the friction estimated value is saturated, so that the jerky feeling can be prevented.
[0036]
That is, when estimating friction, if there is a model error or a signal has noise, it is erroneously estimated as friction, and the friction compensation control becomes oscillatory or gives a strange jerky feeling to the driver. there is a possibility.
[0037]
(4) The friction estimating unit applies the low-pass filter H (s) having the inverse characteristic of the model P (s) to specify the frequency band of the friction elimination. It is possible to prevent the occurrence of the jerky feeling as described in the effect.
[0038]
(5) The vehicle speed sensor 7 for detecting the vehicle speed is provided, and the friction compensator performs the compensation by removing the friction only when the detected vehicle speed is equal to or less than the predetermined vehicle speed. Therefore, when the self-aligning torque is removed together with the friction. , The effect on vehicle performance can be reduced.
[0039]
That is, at low speeds, there is no problem, but at high speeds, the reaction force near neutral becomes weak. Therefore, it is desirable to execute the control of the present invention only at low speeds. In addition, at low speed, there is an advantage that the restorability of the steering wheel is greatly improved.
[0040]
(Second embodiment)
In the first embodiment, the friction torque is estimated using the steering shaft rotation angle α, whereas in the second embodiment, the friction torque is estimated using the steering angular velocity η. Since the system configuration is the same as that of the first embodiment shown in FIG. 1, illustration and description are omitted.
[0041]
Next, the operation will be described.
[Effect of friction estimation when detecting angular velocity]
FIG. 3 is an operation reaction force generation control block diagram of the second embodiment for estimating the friction torque based on the steering angular velocity η. To obtain the steering angular velocity η, it is desirable to use the signal of the tachometer. However, it is also possible to obtain α (angle) from the encoder and obtain the steering angular velocity η from the difference. However, in this case, care should be taken so that the resolution of the steering angular velocity η can be sufficiently obtained.
[0042]
As described above, in a state where disturbances Ts and Tf are not applied to the plant,
Js · η ′ = Kt · i (5)
Therefore, when expressed by a transfer function, s is expressed as a Laplace operator as follows.
η / i = Kt / (Js · s) = Q (s) (6)
The frequency band of disturbance elimination is defined as fc (Hz), and ωc = 2πfc (rad / s).
A low-pass filter for disturbance rejection,
G (s) = ωc / (s + ωc) (7)
And
In this state, if a controller is configured around the control target (plant) as shown in FIG. 3, the friction torque estimated from the portion A in FIG. 3 is obtained by converting it into a current value, as in FIG. Is fed back to the input current as shown in FIG. Thus, friction is removed.
[0043]
Next, effects will be described.
In the operation reaction force generation control device of the second embodiment, the effects (1) to (5) of the first embodiment can be obtained. However, the effects (1) and (2) of the first embodiment are expressed as the following (1 ′) and (2 ′).
[0044]
(1 ′) A steering wheel 1 for a driver to input a command value for a change in direction of a vehicle, a motor 3 for adjusting an operation reaction force applied to the steering wheel 1, and a steering for controlling a generated force of the motor 3 An operation reaction force generation control device including a reaction force controller 8; a torque sensor 6 for detecting a driver steering torque Ts of the driver with respect to the steering wheel 1; and a rotary sensor for detecting a steering angular velocity η generated by the operation of the driver. An encoder 4 or a tachogenerator is provided, and the steering reaction force controller 8 controls the motor 3 and the reduction gear 2 based on the detected driver steering torque Ts, the detected steering angular velocity η, and the added control input. A friction estimating unit for estimating the friction of the actuator unit, and a method for removing the estimated friction. And a friction compensator that changes the control input, so that the friction at the time of operating the operation input means is rationally estimated and removed, so that the driver can obtain the road surface condition and other necessary information with a small torque. In addition to being able to convey, it is possible to hope for an improved steering feeling without friction in the operation system.
[0045]
(2 ′) The friction estimating unit has a model Q (s) driven by the control input and the driver's operation force, and controls the steering angular velocity η when the steering angular velocity η is passed through the inverse characteristic of the model Q (s). From the difference between the estimated value of the sum of the input and the operation input and the total value of the actual control input and the operation input, the force input as the disturbance is used as the friction estimation value, so that a reasonable friction estimation configuration can be provided. it can.
[0046]
(Third embodiment)
First, the configuration will be described.
The third embodiment describes a case where the operation reaction force generation control device of the present invention is applied to a steering reaction force generation unit of an electric power steering.
[0047]
FIG. 4 is a block diagram of a vehicle steering system according to a third embodiment of the present invention. A torque sensor 6 for detecting a steering torque applied to the steering wheel 1 and a motor 3 for assisting steering are arranged on a steering shaft 5 that connects the steering wheel 1 and a steering mechanism 9 that performs a steering operation.
[0048]
The steering wheel 1 is rotatably provided around an axis in a vehicle interior (not shown) so as to face a driver. The steering mechanism 9 is configured by a rack and pinion type steering device including a pinion 10 integrally formed at a lower end of the steering shaft 5 and a rack shaft 11 that meshes with the pinion 10.
[0049]
The rack shaft 11 is fixed to a front portion of a vehicle (not shown) so as to be slidable in the left and right direction. Both ends of the rack shaft 11 are connected to steering wheels 14 and 15 via left and right tie rods 12 and 13. Are linked. The motor 3 for assisting the steering is connected to the steering shaft 5 via a reduction gear 2 that converts the torque generated by the motor 3 into the rotation torque of the steering shaft 5.
[0050]
Next, a control system according to a third embodiment will be described with reference to a control block diagram shown in FIG.
When the driver operates the steering wheel 1, the wheels 14, 15 are steered by mechanical connection. The torque sensor 6 detects the torsion steering torque by the load at this time. The output of the torque sensor 6 is supplied to a steering reaction force controller 8 that controls and drives the steering assist motor 3.
[0051]
The steering reaction force controller 8 is further input with a rotation angle output from a rotary encoder 4 or a tachometer for measuring the rotation angle and rotation speed of the motor 3. Also, signals from a vehicle speed sensor 7 and the like for detecting the traveling speed of the vehicle are provided.
[0052]
The output of the steering reaction force controller 8 is given to the motor 3, and calculates the drive current of the motor 3 using the steering torque, the rotation angle, the rotation speed, the vehicle speed, and the like of the motor. The motor 3 is controlled and driven while referring to the motor current by the built-in motor current sensor. Power supplied to the motor is provided by a battery 16.
[0053]
[Effect of friction estimation at angle detection]
FIG. 6 is an operation reaction force generation control block diagram of the third embodiment that performs static friction estimation based on the motor angle α and compensates for dynamic friction based on the motor rotation speed.
Driver steering torque: Ts (disturbance known)
Friction torque and road input torque: Tf (unknown disturbance)
Moment of inertia of steering system (including motor): Js
Motor torque constant: Kt
Motor generated torque: Tm
Motor applied current: i
Rotation angle of steering shaft: α = θ / reduction ratio
Then, the equation of motion is as follows.
Js · α ″ = Ts + Tm + Tf (1)
In the state where disturbances Ts and Tf are not added to the plant,
Js · α ″ = Kt · i (2)
Therefore, when expressed by a transfer function, s is expressed as a Laplace operator as follows.
α / i = Kt / (Js · s ² ) = P (s) (3)
The frequency band of disturbance elimination is defined as fc (Hz), and ωc = 2πfc (rad / s).
A low-pass filter for disturbance rejection,
H (s) = ωc ² / (S + ωc) ² … (4)
And In this state, when a controller is configured around the control target as shown in FIG. 6, the unknown disturbance torque estimated from the part A in FIG. 6 is calculated.
[0054]
In the electric power steering, the relationship between the disturbance (the friction torque and the input torque from the road surface) with respect to α is as shown in FIG. 7 (disturbance torque = friction torque + tire restoration torque), and the estimated unknown disturbance torque is represented by B By differentiating (high-pass filter) in the section, it is possible to estimate the equivalent of static friction at the time of minute steering.
[0055]
In addition to the static friction, a previously known dynamic friction is calculated from the part C, and both are added to be a friction. By converting it into a current value and feeding it back to the input current as shown in FIG. 5, friction is removed.
[0056]
Next, effects will be described.
In the operation reaction force generation control device of the third embodiment, the following effects can be obtained.
[0057]
(3) A steering wheel 1 for the driver to input a command value for changing the direction of the vehicle, a motor 3 for adjusting the operation reaction force applied to the steering wheel 1, and a steering reaction for controlling the generated force of the motor 3 A torque sensor 6 for detecting a driver's operating force on the steering wheel 1 and a rotary encoder for detecting a steering shaft rotation angle α generated by the driver's operation. The steering reaction force controller 8 controls the actuator unit by the motor 3 and the reduction gear 2 based on the detected driver steering torque Ts, the detected steering shaft rotation angle α, and the added control input. A friction estimating unit (part B) for estimating static friction and a steering shaft rotational angular velocity α ' A friction storage unit (C unit) storing the dynamic friction of the actuator unit, a friction compensating unit for changing a control input based on the estimated static friction and the stored dynamic friction so as to remove both frictions, , It is possible to compensate for both static friction and dynamic friction, and the effect of eliminating the frictional feeling of the operation system and improving the steering feeling of the vehicle can be expected. In addition, necessary information such as road surface conditions transmitted via tires can be transmitted.
[0058]
(4) The friction compensator changes the control input according to the value obtained by applying a high-pass filter to the output of the friction estimator (B) and the value output from the friction storage (C). It is possible to estimate the equivalent of static friction at the time of minute turning, and it is possible to improve the steering feeling at the time of minute turning.
[0059]
(Fourth embodiment)
Since the system configuration is the same as that of FIG. 4 of the third embodiment, illustration and description are omitted.
[0060]
Next, the operation will be described.
[Effect of friction estimation at angle detection]
FIG. 8 is an operation reaction force generation control block diagram of the fourth embodiment. Since the process of calculating the unknown disturbance torque is the same as that of the third embodiment, the description is omitted.
[0061]
In the fourth embodiment, the estimated value of the disturbance torque is provided with a limiter equivalent to dynamic friction (D part). Thereafter, a first friction compensation value (E part) multiplied by a first gain G1 of 1 or less is calculated. In addition, the dynamic friction that is known in advance is calculated from the steering shaft rotation angular velocity α ′, and then a second friction compensation value (F section) is calculated by multiplying the gain by a gain of 2 or less. Then, the two are added to obtain a friction compensation value.
[0062]
Further, by setting the sum of the first gain G1 and the second gain G2 to 1 or less, the friction calculated by adding the two becomes closer to the actual friction value, thereby realizing a more natural steering feeling. it can.
[0063]
Also, as the vehicle speed increases, the steering speed generally decreases, and the steering wheel stops, minute operation, and stop are repeated. In such a case, a change from static friction to dynamic friction tends to occur. Therefore, when the vehicle speed is high, the first gain G1 is increased and the second gain G2 is reduced, thereby eliminating the frictional feeling at a high vehicle speed. Can be.
[0064]
In the case of electric power steering, the steering force near the steering center is low. When the steering force is low, a slight torque fluctuation is easily felt. Therefore, when the steering angle is small, the first gain G1 is increased and the second gain G2 is decreased, so that the feeling of friction at the time of minute steering can be eliminated. .
[0065]
Furthermore, when the steering speed is high, only dynamic friction is involved. Therefore, when the steering speed is high, the first gain G1 is reduced and the second gain G2 is increased, so that the feeling of friction can be eliminated.
[0066]
Next, effects will be described.
In the operation reaction force generation control device of the fourth embodiment, the following effects can be obtained.
[0067]
(5) The friction compensating unit is configured to multiply the output of the friction estimating unit (D unit) by a first gain G1 of 1 or less and a second friction compensation value of 1 or less to the output of the friction storage unit (C unit). The sum of the gain G2 and the second friction compensation value is used as the friction compensation value, and the sum of the first gain G1 and the second gain G2 is set to 1 or less. , And a more natural steering feeling can be realized.
[0068]
(6) A vehicle speed sensor 7 for detecting the vehicle speed is provided. The first friction compensator (E) increases the first gain G1 at a high vehicle speed, and the second friction compensator (F) Since the two gains G2 are reduced, the feeling of friction at high vehicle speed can be eliminated and the steering feeling can be improved.
[0069]
(7) When the steering angle is small, the first friction compensator (E) increases the first gain G1, and the second friction compensator (F) decreases the second gain G2. Therefore, it is possible to improve the steering feeling by suppressing the torque fluctuation at the time of minute turning.
[0070]
(8) When the steering speed is high, the first friction compensator (E) lowers the first gain G1, and the second friction compensator (F) increases the second gain G2. Therefore, it is possible to eliminate the feeling of friction when the steering speed is high.
[0071]
As described above, the operation reaction force generation control device of the present invention has been described based on the first to fourth embodiments. However, the specific configuration is not limited to these embodiments, and claims Changes and additions of the design are permitted without departing from the gist of the invention according to each of the claims.
[0072]
For example, in the first embodiment and the second embodiment, the steer-by-wire reaction force actuator has been described, but the friction can be similarly removed by the electric power steering.
However, in the electric power steering, not only the friction but also the self-aligning torque generated in the tire is removed. Therefore, a limiter is indispensable for feeding back the friction compensation current shown in FIGS.
[0073]
In the first to fourth embodiments, the motor is used for driving the actuator. However, it is needless to say that the friction can be removed from the actuator by configuring the hydraulic system and performing the same control. .
[Brief description of the drawings]
FIG. 1 is an overall system diagram showing an operation reaction force generation control device according to a first embodiment.
FIG. 2 is an operation reaction force generation control block diagram for estimating a friction torque based on a steering shaft rotation angle in the device of the first embodiment.
FIG. 3 is an operation reaction force generation control block diagram for estimating a friction torque based on a steering angular velocity in the device of the second embodiment.
FIG. 4 is an overall system diagram showing an operation reaction force generation control device according to a third embodiment.
FIG. 5 is a block diagram illustrating a control system according to a third embodiment.
FIG. 6 is an operation reaction force generation control block diagram for estimating a friction torque based on a steering shaft rotation angle in the device of the third embodiment.
FIG. 7 is an operation characteristic diagram of the third embodiment.
FIG. 8 is an operation reaction force generation control block diagram for estimating a friction torque based on a steering shaft rotation angle in the device of the fourth embodiment.
FIG. 9 is an operation characteristic diagram of the fourth embodiment.
[Explanation of symbols]
1 Steering wheel (operation input means)
2 Reduction gear
3 Motor (actuator)
4 rotary encoder (operation state quantity detection means)
5 Steering shaft
6. Torque sensor (operating force detecting means)
7 Vehicle speed sensor (vehicle speed detection means)
8. Steering reaction force controller (control means)
9 Steering mechanism
10 pinions
11 Rack axis
12 Tie rod
13 Tie rod
14 wheels
15 wheels
16 Battery

Claims (10)

An operation input means for the driver to input a command value for changing the direction of the vehicle, an actuator for adjusting an operation reaction force applied to the operation input means, and a control means for controlling a generated force of the actuator. In the operation reaction force generation control device,
Operating force detecting means for detecting an operating force on the driver's operation input means,
Operation state amount detection means for detecting displacement or speed of the operation input means caused by the operation of the driver,
The control means,
Based on the detected operation force, the detected displacement or speed of the operation input unit, and the applied control input, a friction estimation unit that estimates the friction of the actuator unit,
A friction compensator that changes the control input so as to remove the estimated friction,
An operation reaction force generation control device, comprising: The operation reaction force generation control device according to claim 1,
The friction estimation unit has a model driven by a control input and a driver's operation force, and a control input obtained when an operation state amount by displacement or speed of the operation input unit is passed through the inverse characteristic of the model. An operation reaction force generation control device, wherein a force input as a disturbance is used as a friction estimated value based on a difference between an estimated value of a total of operation inputs and a total value of an actual control input and an operation input. The operation reaction force generation control device according to claim 1 or 2,
The operation reaction force generation control device, wherein the friction compensating unit sets an upper limit on the estimated friction value, and removes a friction that is equal to or less than the upper limit value. The operation reaction force generation control device according to claim 2,
The operation reaction force generation control device, wherein the friction estimating unit applies a low-pass filter having an inverse characteristic of the model to specify a frequency band for removing friction. The operation reaction force generation control device according to any one of claims 1 to 4,
Providing vehicle speed detection means for detecting vehicle speed,
The operation reaction force generation control device, wherein the friction compensating unit performs compensation by removing the friction only when the detected vehicle speed is equal to or lower than a predetermined vehicle speed. An operation input means for the driver to input a command value for changing the direction of the vehicle, an actuator for adjusting an operation reaction force applied to the operation input means, and a control means for controlling a generated force of the actuator. In the operation reaction force generation control device,
Operating force detecting means for detecting an operating force on the driver's operation input means,
Operation state amount detection means for detecting displacement or speed of the operation input means caused by the operation of the driver,
The control means,
Based on the detected operation force and the detected displacement or speed of the operation input unit, based on the applied control input, a friction estimation unit that estimates the friction of the actuator unit,
A friction storage unit that stores the friction of the actuator unit according to the speed of the operation input unit,
A friction compensator that changes a control input so as to remove both frictions based on the estimated friction and the stored friction;
An operation reaction force generation control device, comprising: The operation reaction force generation control device according to claim 6,
The operation reaction force generation control device, wherein the friction compensator changes a control input according to a value obtained by applying a high-pass filter to an output of the friction estimator and a value output from a friction memory. The operation reaction force generation control device according to claim 6 or 7,
The friction compensator outputs a control output according to a sum of a value obtained by multiplying the output of the friction estimator by a first gain of 1 or less and a value obtained by multiplying the output of the friction storage by a second gain of 1 or less. change,
An operation reaction force generation control device, wherein an added value of the first gain and the second gain is set to 1 or less. The operation reaction force generation control device according to claim 7,
Providing vehicle speed detection means for detecting vehicle speed,
The control device according to claim 1, wherein the friction compensator changes at least one of the first gain and the second gain according to the detected vehicle speed. The operation reaction force generation control device according to claim 8,
The operation reaction force generation control device, wherein the friction compensator changes at least one of the first gain and the second gain in accordance with the detected displacement or speed of the operation input means.

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