JP5141059B2 - Control device for electric power steering device - Google Patents

Description

  The present invention relates to a control device for an electric power steering apparatus in which a steering assist force by a motor is applied to the steering of a vehicle. The present invention relates to a control device for an electric power steering apparatus that calculates a correction value so that a set ratio is obtained, corrects an assist amount (assist torque) with the calculated correction value, and appropriately adjusts a steering torque.

  An electric power steering device for energizing a vehicle steering device with an auxiliary load by a rotational force of a motor energizes an auxiliary load to a steering shaft or a rack shaft by a transmission mechanism such as a gear or a belt via a speed reducer. It is supposed to be. Such a conventional electric power steering apparatus performs feedback control of motor current in order to accurately generate assist torque (steering assist force). In the feedback control, the motor applied voltage is adjusted so that the difference between the current command value and the motor current detection value becomes small. Generally, the adjustment of the motor applied voltage is a duty of PWM (pulse width modulation) control. This is done by adjusting the tee ratio.

  Here, the general configuration of the electric power steering apparatus will be described with reference to FIG. 18. The column shaft 2 of the handle 1 is connected to a tie rod 6 of a steered wheel via a reduction gear 3, universal joints 4 a and 4 b, and a pinion rack mechanism 5. It is connected to. The column shaft 2 is provided with a torque sensor 10 that detects the steering torque of the handle 1, and a motor 20 that assists the steering force of the handle 1 is connected to the column shaft 2 via the reduction gear 3. A power is supplied from the battery 14 to the control unit 30 that controls the power steering device, and an ignition signal is input through the ignition key 11. The control unit 30 detects the steering torque Th detected by the torque sensor 10 and the vehicle speed. An assist command steering assist command value I is calculated based on the vehicle speed V detected by the sensor 12, and a current supplied to the motor 20 is controlled based on the calculated steering assist command value I.

  The control unit 30 is mainly composed of a CPU (including MPU and MCU). FIG. 19 shows general functions executed by a program inside the CPU.

  The function and operation of the control unit 30 will be described with reference to FIG. 19. The steering torque Th detected by the torque sensor 10 is input to the steering assist command value calculation unit 32, and the vehicle speed V detected by the vehicle speed sensor 12 is also steered. This is input to the auxiliary command value calculation unit 32. The steering assist command value calculation unit 32 refers to the assist map stored in the memory 33 based on the input steering torque Th and the vehicle speed V, and the steering assist command is a control target value of the current supplied to the motor 20. Determine the value I. The steering assist command value I is input to the subtraction unit 30A and is also input to the feedforward differential compensation unit 34 for increasing the response speed, and the deviation (Ii) of the subtraction unit 30A is input to the proportional calculation unit 35. At the same time, it is input to the integral calculation unit 36 for improving the characteristics of the feedback system, and its proportional output is input to the addition unit 30B. The outputs of the differential compensator 34 and the integral compensator 36 are also added to the adder 30B, and the current control value E, which is the addition result of the adder 30B, is input to the motor drive circuit 37 as a motor drive signal. Electric power is supplied from the battery 14 to the motor drive circuit 37, the motor current value i of the motor 20 is detected by the motor current detector 38, and the motor current value i is input to the subtractor 30A and fed back.

  In such an electric power steering device, a vehicle in a straight traveling state causes a side slip angle and a lateral force when the steered wheels are steered by steering the steering wheel 1 from the driver, and a lateral force is generated. When a rotational moment is generated, it changes to a turning state. Thereafter, a side slip angle is also generated in the rear wheel, and a steady turning state is obtained by a balance between the lateral force generated in the front wheel and the rear wheel and the rotational moment of the center of gravity of the vehicle. Thus, the lateral force generated in the front wheel is transmitted to the handle 1 as a rotational reaction force around the kingpin axis, that is, as a self-aligning torque (hereinafter referred to as “SAT”). Further, when the steering wheel 1 is steered, the change in the side slip angle generated in the front wheel becomes a further change in the SAT, and the change is transmitted from the front wheel to the steering wheel 1 and the driver.

SAT is a force for returning the steering wheel to the original position, and as shown in FIG. 20, a steering torque Th is generated when the driver steers the steering wheel, and the motor M generates an assist torque Tm according to the steering torque Th. To do. As a result, the front wheels are steered and SAT is generated as a reaction force. At that time, a torque that becomes a steering steering resistance is generated by the equivalent inertia J that combines the inertia of the motor M and the inertia of the steering mechanism portion and the friction torque Fr, and considering the balance of these forces, Is obtained. Note that ω is an angular velocity and ω ^* is an angular acceleration.

また、図２１は、横力の着力点が前輪Ｗｆの中心線ＣＬ１よりもニューマチックトレールξｎ分だけ後方にある様子を示し、ハンドルの戻りを良くするためのキャスタ角によるキャスタトレールξｃが、前輪Ｗｆの中心線ＣＬ１より前方にあることを示している。ここで、前輪Ｗｆの片輪にかかるＳＡＴは横力とトレールの積（横力×トレール）であり、つまり、トレールをξ、横すべり角をβｆ、前輪ＷｆのコーナリングパワーをＫｆとすると、ＳＡＴは下記数２で求めることができる。なお、横すべり角βｆとコーナリングパワーＫｆの乗算値を横力、ニューマチックトレールξｎとキャスタトレールξｃの加算値をトレールξとする。横すべり角βｆが小さい場合は、横すべり角βｆと横力は線形と見なして良いからである。

FIG. 21 shows a state in which the point of application of the lateral force is behind the center line CL1 of the front wheel Wf by the pneumatic trail ξn. The caster trail ξc based on the caster angle for improving the return of the steering wheel is It shows that it is ahead of the center line CL1 of Wf. Here, the SAT applied to one wheel of the front wheel Wf is the product of lateral force and trail (lateral force x trail), that is, assuming that the trail is ξ, the side slip angle is βf, and the cornering power of the front wheel Wf is Kf, It can be obtained by the following formula 2. Note that the product of the side slip angle βf and the cornering power Kf is the lateral force, and the sum of the pneumatic trail ξn and the caster trail ξc is the trail ξ. This is because when the side slip angle βf is small, the side slip angle βf and the side force may be regarded as linear.

図２２は、横すべり角βｆに対するＳＡＴ及び横力の変化を示す特性図であり、横すべり角βｆが増加するに従って横力及びＳＡＴも増加し、横力が飽和するとＳＡＴが徐々に減少し始め、グリップを失っていく様子を示している。

FIG. 22 is a characteristic diagram showing changes in the SAT and the lateral force with respect to the side slip angle βf. As the side slip angle βf increases, the side force and the SAT also increase. When the side force is saturated, the SAT begins to gradually decrease, and the grip It shows a state of losing.

  Next, the manner in which the front wheels roll while sliding will be described with reference to FIGS. 23, 24 and 25. FIG.

  FIG. 23 is a diagram showing the lateral force generated on the entire ground contact surface of the tire. The tire is deformed in the lateral direction of the tread portion (shaded portion) by the lateral force, and the SAT acts in a direction to reduce the lateral slip angle βf. Is shown. FIG. 24 is a diagram showing in detail the shaded area in FIG. 23, and shows the point of application of lateral force (the center of gravity of the shaded area), the adhesion area, the contact length, and the slip area.

  FIG. 25 shows the change in the adhesive area in the shaded area in FIG. 24 as a triangle, and shows the change in the pneumatic trail ξn. As the side slip angle βf increases, the triangle ABC1 changes from the triangle ABC2 to the triangle ABC3, and changes in the force points corresponding to the change in the triangle are indicated by P1, P2, and P3, respectively. Further, the change of the pneumatic trail ξn accompanying the change of the side slip angle βf is shown corresponding to the applied points P1 to P3 of the resultant force of the triangles ABC1 to ABC3. That is, when the side slip angle βf increases, the resultant force to the triangles ABC1 to ABC2 increases, but the pneumatic trail ξn does not change, and when it changes to the triangles ABC2 to ABC3, the resultant force does not change, and a change appears in the pneumatic trail ξn. It shows a state. If the friction coefficient μ of the front wheels is the same, the force at which the front wheels begin to slide is not changed.

  In such an electric power steering apparatus, for example, when the driver tries to correct the behavior of the vehicle during cornering, the driver feels SAT and steers to correct the behavior of the vehicle. However, if the timing and magnitude of receiving the lateral acceleration and the yaw rate accompanying the change in the behavior of the vehicle change, the driver cannot always feel a substantially constant steering feeling depending on the change situation.

  As an apparatus for solving such a problem, for example, there is an apparatus disclosed in Japanese Patent Laid-Open No. 2003-285754 (Patent Document 1). In the apparatus disclosed in Patent Document 1, the driver always feels that the steering feeling is almost constant even when the behavior of the vehicle changes. That is, an electric power steering apparatus for an automobile that assists steering of a steering wheel by a motor, a torque sensor that detects a steering torque, and a first control unit that sets a control amount of the motor so as to reduce the value of the torque sensor A second control unit that sets a control amount of the motor so that the relationship between the steering force felt by the driver and the behavior of the vehicle felt by the driver is a preset relationship, and the first control unit and the second control unit And a motor control unit that controls the motor with a control amount obtained by adding the respective control amounts.

Further, in the apparatus disclosed in Japanese Patent Application Laid-Open No. 2006-131064 (Patent Document 2), the lateral force acting on the wheel is specified by directly detecting the lateral force acting on the front wheel and the rear wheel, and the assist is detected. Torque response and control accuracy are improved. Further, the assist torque is corrected so as to suppress the change in the yaw rate during cornering, thereby prompting the driver to make a correction steering. That is, in the steering device, each of the front wheels and the rear wheels is detected, and a detection unit that directly detects the lateral force acting on the wheel, and a steering system that transmits the operation amount of the handle operated by the driver to the wheel. And a processing unit for correcting the assist torque applied to the steering system based on the lateral force acting on the front wheel and the lateral force acting on the rear wheel. And a controller for controlling the actuator based on the assist torque.
JP 2003-285754 A JP 2006-131064 A

  However, the apparatus of Patent Document 1 uses a target steering characteristic model to calculate and output a steering feeling that is substantially constant, so that the driver cannot accurately determine the SAT. is there. That is, it may be difficult for the driver to grasp the behavior of the vehicle. Further, in the device of Patent Document 2, the lateral force of the front wheels and the rear wheels is detected and the target steering torque is calculated and corrected, but various detection sensors for detecting the behavior of the vehicle are required. Since a CPU having a high function and a high processing capacity is required, there is a problem that costs increase.

  The present invention has been made under the circumstances described above, and an object of the present invention is to obtain an appropriate steering reaction force (steering torque) in accordance with the behavior of the vehicle, that is, with respect to the magnitude and change amount of the SAT. This makes it easier for the driver to predict the behavior of the vehicle, makes it easier to detect the start of slipping during steering, and prevents the steering wheel from being increased, making it relatively inexpensive and highly reliable. An object of the present invention is to provide a control device for an electric power steering device.

The present invention relates to a control device for an electric power steering apparatus that drives and controls a motor that applies assist torque to a steering system based on a current command value calculated based on the steering torque and the vehicle speed, and the object of the present invention is to estimate SAT. a SAT estimating means for, the assist gain calculator for calculating the assist gain is the ratio of the assist torque and the steering torque, and F adjusting means for setting the ratio of the change amount of the steering torque with respect to a change amount of the SAT provided, wherein said assist gain obtained by the assist gain computation unit, on the basis of the ratio set in the F adjusting means obtains the SA T gain, based on the SA T gains obtained, the SAT adjust the SAT estimation value obtained by the estimating means, the adjustment has been estimated SAT value and SAT feedback compensating value, the SAT It is achieved by correcting the assist torque by the fed back compensation value.

Further, the object of the present invention is that the ratio is set according to the vehicle speed, or the ratio is set according to the angular speed of the motor, the column angular speed or the rack speed. Or the ratio is set according to the SAT estimated value and the angular velocity of the motor, or the column angular velocity or the rack speed, or the ratio is the SAT estimated value. And the ratio is set in accordance with the determination signal for the increase / return of the steering wheel, or the ratio is the angular velocity of the motor or the column angular velocity or the rack speed, the vehicle speed, the SAT estimated value, and the steering wheel. It is set according to the decision signal for the increase / decrease of the signal, or the decision signal is increased , The absolute value decreases the SAT estimated value, and when the absolute value of the change amount of the SA T is smaller than a predetermined value, so that the amount of change in the steering torque is the amount of change and the positive correlation of the SAT, When the ratio is set or when the determination signal is increased, the absolute value of the SAT estimated value is decreased, and the absolute value of the change amount of the SAT is a predetermined value or more. such that said amount of change steering torque is the amount of change and the negative correlation of the SAT, by being adapted to set the ratio, or the predetermined value the speed or the motor angular velocity or column velocity, or by adapted to vary the vehicle speed and the motor angular velocity or column velocity, or the assist gain calculator includes a current command value to calculate the amount of change in the current command value variance A reduction amount calculating means, by dividing the amount of change in the current command value with variation of the steering torque, by being constituted by a divider for calculating the assist gain, or a subsequent stage of the SAT estimating means, Or, by providing a phase compensation means at the subsequent stage of the assist gain computing unit, or by means of the phase compensation means for computing a future compensation value based on the current value and the past value, Alternatively, this can be achieved more effectively by providing a high-frequency noise removal filter in the subsequent stage or the previous stage of the assist gain calculation section.

  According to the control device for the electric power steering apparatus of the present invention, the SAT feedback gain is adjusted so that the change amount of the SAT that changes depending on the state of the vehicle and the change amount of the steering torque from the driver become a preset ratio. Since the assist amount (assist torque) is corrected, it becomes easy to feel a change in SAT that appears as a change in the behavior of the vehicle as a change in the steering torque, and the driver can appropriately recognize the steering situation. Since it becomes easy to predict the behavior, driving becomes easy.

  Further, since the steering torque is adjusted based on the amount of change in SAT, it is possible to detect the start of slipping during the steering of the vehicle and to correct the steering torque so as to suppress the steering wheel from being increased.

  The control device for an electric power steering apparatus according to the present invention includes F adjustment means for setting a ratio of change in SAT and change in steering torque, and assist gain and F adjustment means that are a ratio of assist torque and steering torque. Thus, the SAT feedback gain is obtained, the SAT is adjusted based on the SAT feedback gain, and the assist torque is corrected by the adjusted SAT feedback compensation value. It becomes easier to steer in a safe direction.

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

  First, a basic control system as a premise of the present invention will be described with reference to FIG. The configuration of FIG. 1 is configured based on Equation 1 above.

The steering torque Th detected by the torque sensor is input to the assist map 59, the differentiator 51 and the adding unit 45B in the SAT estimating means 40, and the basic assist torque Tha calculated by the assist gain Km in the assist map 59 is added / subtracted unit 50A. The steering torque differentiated by the differentiator 51 for differential compensation is multiplied by the gain Kd in the gain unit 52, and the compensated differential compensation torque Thb is added to the addition / subtraction unit 50A. The SAT estimated value SAT ^* estimated by the SAT estimating means 40 is gain-calculated by the gain unit 43, the SAT feedback compensation value SAT ^* _f from the gain unit 43 is subtracted and input to the adder / subtractor 50A, and the adder / subtractor 50A The processed current command value I is input to the transfer function unit 53 and the transfer function unit 44. Each of the transfer function units 53 and 44 has a transfer function Kt · G (Kt is a motor torque constant, G is a reduction gear ratio), and the transfer function unit 53 is an assist torque actually generated by the motor and the reduction gear. The transfer function unit 44 is a block indicating that conversion is performed using estimated logic (software).

  The assist torque TA multiplied by the transfer function Kt · G in the transfer function unit 53 is input to the subtracting unit 50B in the block A, and the assist (assist) by the motor multiplied by the transfer function Kt · G in the transfer function unit 44 is performed. ) Torque Tm (= I · Kt · G) is input to the adder 45B, and the torque signal Th + Tm added to the steering torque Th by the adder 45B is input to the subtractor 45C.

Block A is a transfer function block in which the mechanism is simply modeled, J is inertia (= equivalent inertia combining motor inertia and inertia of the steering mechanism), and Fr is friction torque. Further, the actual SAT from the vehicle is subtracted and input to the subtracting unit 50B in the block A, and the angular velocity (column shaft angular velocity) ω _A from the block 58 is subtracted by the Fr · sign (ω _A ) via the friction calculating unit 54. The acceleration torque TC, which is the result of the subtraction processing by the subtraction unit 50B, is fed back to the block 58. The angular velocity ω _A from the block 58 is integrated by the integrator 57 to become an angle θ. The angle θ is input to an angle detection unit such as a resolver (not shown), the detected angle θ is input to the angular velocity calculation unit 56, and the angular velocity ω calculated by the angular velocity calculation unit 56 is the angular acceleration calculation unit 55 and the SAT estimation unit 40. The angular acceleration ω ^* is calculated by the angular acceleration calculating unit 55. The angular acceleration ω ^* is input to the inertia calculation unit 47 in the SAT estimation unit 40.

Incidentally, the block 57 is intended to indicate a transfer function of an angle theta from the column shaft angular velocity omega _A, rather than measuring the column shaft angular velocity omega _A direct angle of the motor obtained through a reduction gear of the speed reduction ratio G theta Is obtained to obtain the angular velocity ω and the motor angular velocity / reduction ratio is obtained, which becomes the column shaft angular velocity, but substantially ω _A = ω.

On the other hand, the angular velocity ω calculated by the angular velocity calculating unit 56 is input to the adding unit 45A as Fr · sign (ω) via the friction calculating unit 41 in the SAT estimating means 40, and the angular acceleration from the angular acceleration calculating unit 55 is input. ω ^* is input to the inertia calculation unit 47, J · ω ^*, which is the output of the inertia calculation unit 47, is input to the addition unit 45A, and the calculation value h (= J · ω ^* + Fr · sign (ω)) is subtracted and input to the subtracting unit 45C. In the subtraction unit 45C, the calculation value h is subtracted from the torque signal Th + Tm, and the subtraction result is input to the Q filter 42 for feeding back only information necessary and sufficient to improve the steering feeling of the driver. 42 SAT estimation value SAT ^* which is the output of, is input to the gain unit 43 having a SAT gain Ks are set so that the steering torque matches the behavior of the vehicle driver, SAT feedback compensation from the gain unit 43 The value SAT ^* _f is subtracted and input to the addition / subtraction unit 50A.

  The SAT estimation means 40 includes a friction calculation unit 41, a Q filter 42, a transfer function unit 44, an inertia calculation unit 47, and the like.

In the basic control system of FIG. 1 as the premise of the present invention, the SAT feedback compensation value SAT ^* _f calculated by the SAT estimation means 40 and the gain unit 43 is input to the addition / subtraction unit 50A, and the basic steering torque Tha and the differential are calculated. The current command value I, that is, the assist torque TA is corrected by subtracting from the added value of the compensation torque Thb. Then, the SAT gain Ks of the gain unit 43 is adjusted so that the ratio of the change amount of the SAT and the change amount of the steering torque Th becomes the ratio F. The principle of correcting the assist amount by adjusting the SAT gain Ks will be described below. To do.

  First, when the force balance equation at the time point k is expressed based on the above equation 1, the following equation 3 is obtained.

ここで、Ｋｍはアシストマップ５９のアシストゲイン、Ｋｄはゲイン部５２に設定されているゲインである。

Here, Km is an assist gain of the assist map 59, and Kd is a gain set in the gain unit 52.

  And the balance of the force at the time point (k + 1) is the following formula 4.

ここで、静的状態においては、ω^＊（ｋ＋１）＝ω^＊（ｋ）＝０、ω（ｋ＋１）＝ω（ｋ）＝０、ｄＴｈ／ｄｔ（ｋ＋１）＝ｄＴｈ／ｄｔ（ｋ）＝０であり、上記数４と数３の差を求めると、下記数５及び数６になる。

Here, in the static state, ω ^* (k + 1) = ω ^* (k) = 0, ω (k + 1) = ω (k) = 0, dTh / dt (k + 1) = dTh / dt (k) = 0 When the difference between the above equations 4 and 3 is obtained, the following equations 5 and 6 are obtained.

ここで、ＳＡＴの変化量ΔＳＡＴ＝ＳＡＴ（ｋ＋１）−ＳＡＴ（ｋ）、ＳＡＴ推定値ＳＡＴ^＊の変化量ΔＳＡＴ^＊＝ＳＡＴ^＊（ｋ＋１）−ＳＡＴ^＊（ｋ）、操舵トルクＴｈの変化量ΔＴｈ＝Ｔｈ（ｋ＋１）−Ｔｈ（ｋ）である。

Here, SAT change amount ΔSAT = SAT (k + 1) −SAT (k), SAT estimated value SAT ^* change amount ΔSAT ^* = SAT ^* (k + 1) −SAT ^* (k), steering torque Th change amount ΔTh = Th (k + 1) -Th (k).

Then, when ΔSAT = ΔSAT ^* and a ratio F such that ΔTh = F · ΔSAT is defined, the following Expression 7 is obtained.

更に、両辺をＳＡＴの変化量ΔＳＡＴで除算することにより、下記数８が得られる。

Further, the following equation 8 is obtained by dividing both sides by the SAT variation ΔSAT.

そして、上記数８は、下記数９に整理することができる。

The above formula 8 can be rearranged into the following formula 9.

数９をＳＡＴゲインＫｓについて解くと、下記数１０になる。

Solving Equation 9 for the SAT gain Ks yields Equation 10 below.

上記数１０から、ＳＡＴの変化量ΔＳＡＴと操舵トルクＴｈの変化量ΔＴｈの比率Ｆが設定されると、既知のアシストゲインＫｍ、減速ギア比Ｇ及びトルク定数Ｋｔを入力することによりＳＡＴゲインＫｓを得ることができることが分かる。即ち、ＳＡＴの変化量ΔＳＡＴに対する操舵トルクＴｈの変化量ΔＴｈの比率Ｆに基づいて、ゲイン部４３のＳＡＴゲインＫｓを調整することができる。なお、アシストゲインＫｍはアシストマップ５９により事前に求めることができるが、操舵トルクＴｈの変化量ΔＴｈに対する電流指令値Ｉの変化量から求めても良い。

When the ratio F of the change amount ΔSAT of the SAT and the change amount ΔTh of the steering torque Th is set from the above equation 10, the SAT gain Ks is set by inputting the known assist gain Km, the reduction gear ratio G, and the torque constant Kt. It can be seen that it can be obtained. That is, the SAT gain Ks of the gain unit 43 can be adjusted based on the ratio F of the change amount ΔTh of the steering torque Th to the change amount ΔSAT of the SAT. The assist gain Km can be obtained in advance from the assist map 59, but may be obtained from the change amount of the current command value I with respect to the change amount ΔTh of the steering torque Th.

  FIG. 2 shows a characteristic example of the ratio F (= ΔTh / ΔSAT) in the case where the assist gain Km changes with the SAT gain Ks being constant according to the following equation 11, the ratio F is not constant, and the assist gain Km is The ratio F gradually decreases as the ratio increases.

このように、車両の状態を表すＳＡＴの変化量ΔＳＡＴと操舵トルクＴｈの変化量ΔＴｈが特定の比率Ｆになるように設定し、比率Ｆに基づいてゲイン部４３のＳＡＴゲインＫｓを調整し、ＳＡＴゲインＫｓに基づいてＳＡＴ推定値ＳＡＴ^＊を補正し、その補正された補正値をＳＡＴフィードバック補償値ＳＡＴ^＊ _ｆとする。つまり、補正されたＳＡＴフィードバック補償ＳＡＴ^＊ _ｆをアシストトルクに付加（減算）することで、ドライバに操舵状況及び車両の挙動を、より感じさせるように操舵トルクＴｈを補正すると共に、適切な比率Ｆに基づいてアシストトルクを補正するので、安全な舵角方向への操舵を容易にさせることが可能となる。

Thus, the SAT change amount ΔSAT representing the vehicle state and the steering torque Th change amount ΔTh are set to a specific ratio F, and the SAT gain Ks of the gain unit 43 is adjusted based on the ratio F. The SAT estimated value SAT ^* is corrected based on the SAT gain Ks, and the corrected value is set as the SAT feedback compensation value SAT ^* _f . That is, by adding (subtracting) the corrected SAT feedback compensation SAT ^* _f to the assist torque, the steering torque Th is corrected so as to make the driver feel the steering situation and the behavior of the vehicle, and an appropriate ratio F Since the assist torque is corrected based on the above, it is possible to easily perform steering in a safe steering angle direction.

  Based on the principle described above, a first embodiment of the present invention will be described with reference to FIG. 3 corresponds to the basic control system shown in FIG. 1, and the same members are denoted by the same reference numerals and description thereof is omitted.

  The steering torque Th detected by the torque sensor is input to the assist gain calculation unit 61, and the assist gain Km (inclination of the assist map 59) calculated in advance corresponding to the steering torque Th is a transfer function unit (= Kt · G). 64, the transfer function unit 64 performs an operation “Km · Kt · G” and inputs the result to the adder 67B, and “1” of the constant unit 65A is input to the adder 67B and added by the adder 67B. The processed signal “1 + Km · Kt · G” is input to the F adjusting means 60.

In the F adjusting means 60, a ratio F (= ΔTh / ΔSAT) of the steering torque change amount ΔTh to the SAT change amount ΔSAT is set in advance, and is multiplied by the signal “1 + Km · Kt · G” from the adder 67B. The multiplication processing result “F (1 + Km · Kt · G)” is added to the subtraction unit 67A, “1” from the constant unit 65B is subtracted, and the subtraction result “F (1 + Km · Kt · G) − 1 ″ is input to the multiplier 70. Then, the multiplication unit 70 multiplies the SAT estimation value SAT ^* from the SAT estimation means 40, and the multiplication result “SAT ^* · F (1 + Km · Kt · G) −1” is transferred to the transfer function part (= 1 / (Kt · G)) 66 is input and multiplied, and the multiplication result “SAT ^* · {F (1 + Km · Kt · G) −1} / (Kt · G) (= SAT · Ks)” is the SAT feedback compensation value SAT ^*. Subtraction input to the adder / subtractor 50A is performed as _f .

  According to this embodiment, the ratio F of the steering torque change amount ΔTh to the SAT change amount ΔSAT is set in advance, and the assist torque is corrected so as to be the ratio F.

  Next, a second embodiment of the present invention will be described with reference to FIG. 4 corresponding to FIG. 3 (first embodiment).

  In this embodiment, the vehicle speed V detected by the vehicle speed sensor is input to the F adjusting means 60, and the ratio F between the SAT change amount ΔSAT and the steering torque change amount ΔTh is set according to the vehicle speed V. It is like that. That is, the assist torque is corrected using the ratio F set according to the vehicle speed V.

  FIG. 5 shows an example in which the magnitude and change of the steering torque Th according to the vehicle speed V can be achieved by setting the ratio F according to the vehicle speed V as described above. For example, when the steering torque Th is small (the steering wheel is light), the driver cannot feel a sufficient SAT depending on the value of the vehicle speed V, and the vehicle does not give a sense of security because the vehicle fluctuates with a little steering. In the example, the ratio F is set so as to increase the magnitude and change of the steering torque Th so that the steering feeling according to V is sufficiently obtained, and the SAT gain Ks is adjusted. That is, the steering angle θ and the SAT are in a substantially constant relationship when the steering angle θ is small, and the relationship between the SAT and the steering torque Th is the same as in FIG. 5, and the inclination is different. Means different.

  FIG. 6 shows a third embodiment of the present invention corresponding to FIG. 4, and the input to the F adjusting means 60 is changed to the angular velocity ω instead of the vehicle speed V. That is, the angular velocity ω calculated by the angular velocity calculating unit 56 is input to the F adjusting means 60, and the ratio F between the SAT variation ΔSAT and the steering torque Th variation ΔTh is set according to the angular velocity ω. Yes. According to the present embodiment, the assist torque is corrected using the ratio F set according to the angular velocity ω. In this example, the angular velocity ω is calculated by inputting the steering angle θ to the angular velocity calculation unit 56, but may be detected using an angular velocity detection sensor.

  FIG. 7 shows an example in which the magnitude and change of the steering torque Th according to the angular velocity ω can be achieved by setting the ratio F according to the angular velocity ω as described above. For example, when the steering torque Th is small (feels light) with respect to the angular velocity ω, depending on the magnitude of the angular velocity ω, there is a risk of giving the driver a sense of grip. That is, it is necessary to adjust the SAT gain Ks by setting the ratio F so as to increase the change in the steering torque Th as the angular velocity ω increases.

  Further, a fourth embodiment of the present invention will be described with reference to FIG.

In the fourth embodiment, the SAT estimated value SAT ^* and the angular velocity ω estimated by the SAT estimating unit 40 are input to the F adjusting unit 60, and the ratio F is set according to the SAT estimated value SAT ^* and the angular velocity ω. It is like that. That is, in the fourth embodiment, the assist torque is corrected using the ratio F set according to the SAT estimated value SAT ^* and the angular velocity ω.

FIG. 9 is a characteristic example showing the change in the SAT and the rate of change in the SAT with respect to the side slip angle βf. The change in the SAT increases almost linearly when the side slip angle βf is small, but the slope increases as the side slip angle βf increases. It becomes loose, gradually decreases after passing the peak, and further decreases almost linearly. On the other hand, the rate of change of the SAT with respect to the side slip angle βf is constant in the linear increase region and the linear decrease region of the SAT, and exhibits a characteristic of linear slope from positive to negative in the peak region of the SAT. Here, FIG. 10 shows a ratio in which the change in the SAT is made easier to feel by changing the ratio F according to the size of the SAT based on the characteristics of the SAT shown in FIG. 9 in the fourth embodiment of FIG. An example of setting F is shown. For example, in order to allow the driver to easily recognize a change in SAT, in a region where the steering angle θ is small, the rising of the steering torque Th is smoothed and the ratio F is increased gradually. It may be constant as shown by a broken line in the figure. In the region of the steering angle θ where the SAT is increasing linearly, in order to make the change in the steering torque Th linear with the change in the SAT, the region where the ratio F is substantially constant and the steering angle θ is large where the SAT decreases. Then, in order to make it easy to understand the decrease in SAT, the ratio F is increased to make it easier for the driver to understand the phenomenon of vehicle behavior. At this time, the angular velocity information may be used to determine whether the steering angle θ is increased and the SAT is decreased, or whether the steering angle θ is decreased and the SAT is decreased. When the SAT estimated value SAT ^* and the angular velocity ω have the same sign, the ratio F is increased.

  Further, a fifth embodiment of the present invention will be described with reference to FIG.

In this embodiment, an increase / return determination unit 80 and an F setting unit 62 are newly added, and the increase / return determination unit 80 determines increase / return of the handle and outputs a determination signal DS. To do. Then, the determination signal DS is input to the F setting unit 62, the SAT estimated value SAT ^* estimated by the SAT estimation unit 40 is input to the F setting unit 62, and the setting value Ad set by the F setting unit 62 is obtained. This is input to the F adjusting means 60. For example, as shown in Japanese Patent Application Laid-Open No. 2006-248252, the increase / return determination means 80 determines “addition” when the signs of the steering angle θ and the angular velocity ω are the same, and the steering angle θ and the angular velocity. When ω is a different sign, it is determined as “switchback” and a binary (addition / switchback) determination signal DS is output. Further, as disclosed in Japanese Patent Laid-Open No. 2003-170856, when the sign of the steering torque Th and the sign of the steering torque change rate are the same and the absolute value of the steering torque change rate is equal to or greater than a predetermined value, ”, And when the sign of the steering torque Th and the sign of the steering torque change rate are different signs, and the absolute value of the steering torque change rate is equal to or greater than a predetermined value, it may be determined as“ return ”. .

  Next, an operation example of the fifth embodiment of FIG. 11 will be described with reference to the flowchart of FIG.

First, the determination signal DS from the increase / failback determination means 80 and the SAT estimated value SAT ^* from the SAT estimation means 40 are input to the F setting section 62, and the F setting section 62 has the handle set to "addition". It is determined whether or not (step S10), and if “addition” is not determined, a return is returned. On the other hand, if “increase” is determined in step S10, it is determined whether or not the absolute value of the SAT estimated value SAT ^* is decreased (step S11), and the absolute value of the SAT estimated value SAT ^* is decreased. If not, return. If it is determined in step S11 that the absolute value of the SAT estimated value SAT ^* is decreased, the absolute value | ΔSAT | of the change amount ΔSAT of SAT is compared with the magnitude of the predetermined value α (step S12), and the absolute value | When ΔSAT | is smaller than the predetermined value α, the set value Ad is set so as to have a positive correlation (for example, when SAT is decreased, the torque is also decreased) (step S13). If the absolute value | ΔSAT | is equal to or greater than the predetermined value α, the set value Ad is set so as to have a negative correlation (for example, when the SAT decreases, the torque is increased) (step S14). .

As described above, when the absolute value of the SAT estimated value SAT ^* increases when the steering wheel is increased, the assist torque is corrected so that the change amount ΔTh of the steering torque Th is positively correlated with the change amount ΔSAT of the SAT. When the absolute value of the estimated SAT value SAT ^* decreases when the steering wheel is turned back, the assist torque is corrected so that the change amount ΔTh of the steering torque Th is positively correlated with the change amount ΔSAT of the SAT.

Here, the F setting unit 62 determines the set value Ad based on the input SAT estimated value SAT ^* and the determination signal DS for the increment / decrease, and the F adjustment unit 60 sets the set value Ad from the F setting unit 62 to the set value Ad. The ratio F is set accordingly. Hereinafter, a setting example of the ratio F based on the setting value Ad of the F setting unit 62 will be described with reference to FIG. As an example, FIG. 13 shows a case where SAT increases in the positive direction when turning right (the angle θ increases in the positive direction), and left cutting (angle θ increases in the negative direction). ) At 180 degrees around the origin of FIG.

The slope of each line in FIG. 13A is a set value Ad, and for example, when there is a relationship as shown in FIGS. 13B and 13C, that is, the SAT increases linearly with respect to the steering angle θ, Further, when the steering angle θ changes from time t to increase → peak value → decrease, when the steering angle θ is input as a sin wave that rises gently, the SAT also changes to a sin wave shape as shown in FIG. As shown, there is a relationship between the change amount ΔSAT and the change amount ΔTh. If the estimated SAT value SAT ^* increases when the angular velocity ω> 0 is increased, the assist torque is corrected so that the change amount ΔTh of the steering torque Th is positively correlated with the change amount ΔSAT of the SAT estimated value SAT ^* . When the estimated SAT value SAT ^* decreases when the angular velocity ω <0 is switched back, the assist torque is corrected so that the change amount ΔTh of the steering torque Th is positively correlated with the change amount ΔSAT of the SAT estimated value SAT ^* . For example, the characteristics (a) and (d) are 0 → a1 → 0 → d1 → 0.

  Further, the set value Ad is changed according to the vehicle speed V. When the vehicle speed V is increased, the set value Ad is changed as (a) → (b) → (c), and when the vehicle is returned, the vehicle speed V is increased. (D) → (e) → (f). The reason for (a) → (b) → (c) is as described in the second embodiment. Also, the reason why the slopes of (a) and (d) are different is that there is a return force due to an external force (SAT) at the time of return, so that the feeling of return is increased when the torque change is increased and the driver is difficult to steer. This is because the inclination needs to be reduced in order to reduce the driver's feeling of return.

  On the other hand, when the steering wheel is increased and the detected absolute value | ΔSAT | of the change amount ΔSAT is decreasing, that is, in the state of starting to slip, the absolute value | ΔSAT | of the SAT change amount ΔSAT and the magnitude of the predetermined value α When the absolute value | ΔSAT | is smaller than the predetermined value α, the ratio F is set by the set value Ad so as to have a positive correlation. Further, when the absolute value | ΔSAT | is equal to or greater than the predetermined value α, as shown in FIG. 13A, a negative correlation is established according to the angular velocity ω (g) → (h) → (i ) To set the ratio F by the set value Ad. The range of the predetermined value α is to make the steering torque feel lighter as the driver increases the steering wheel. When the SAT is greatly decreased beyond the predetermined value α, the grip of the tire returns to the steering torque. The steering torque is increased so as to urge the direction, that is, the direction of return.

  Thus, according to the present embodiment, before the vehicle becomes uncontrollable, the ratio F is set based on the set value Ad, the SAT gain Ks is adjusted, and the steering torque Th is corrected.

  Further, a sixth embodiment of the present invention will be described with reference to FIG. 14 corresponding to FIG.

In the F setting unit 62 of the present embodiment, the SAT estimation unit 40 supplies the SAT estimated value SAT ^* , the increase / return determination unit 80 determines the steering wheel increase / return determination signal DS, and the angular velocity calculation unit 56 determines the angular velocity ω. The vehicle speed V is input from the vehicle speed sensor, and the set value Ad is set and set by the F setting unit 62 based on the SAT estimated value SAT ^* , the determination signal DS for the increase / return, the angular speed ω, and the vehicle speed V. The set value Ad is input to the F adjustment unit 60, and the ratio F is set by the F adjustment unit 60. Hereinafter, an example in which the ratio F of the F adjusting unit 60 is set by the set value Ad of the F setting unit 62 will be described with reference to FIG.

13 in the sixth embodiment of FIG. 14, SAT estimated value SAT ^* and steer / steer-back determination signal DS, by setting the ratio F according to the vehicle speed V and the angular velocity omega, SAT estimated value SAT ^* and It shows that the ratio F can be obtained so as to increase the magnitude and change of the steering torque Th according to the determination signal DS, the vehicle speed V, and the angular speed ω. For example, as shown in FIG. 13, the ratio F is set by adjusting the set value Ad (inclination) corresponding to the angular velocity ω so that (g) → (h) → (i). The predetermined value α may be increased when the input vehicle speed V is low, and the predetermined value α may be decreased when the vehicle speed V is high. This is because the danger level increases as the vehicle speed V increases, so it is desirable to suppress the increase in speed and lead to a stable direction. Similarly, the greater the angular velocity ω, the higher the degree of danger. Therefore, it is desirable to change the predetermined value α according to the angular velocity ω in order to suppress the increase in speed and lead to a stable direction.

  Here, as shown in FIG. 22 described above, the SAT starts to decrease before the lateral force reaches the peak, and further reducing the SAT by further increasing the handle makes it unstable (course out). That is, as shown in FIG. 13, the range of the predetermined value α (deviation from SAT = 0) is a range for making it easier for the driver to recognize the decrease in SAT. Further, the range of the predetermined value α is set such that the steering torque is felt lighter as the driver increases the steering wheel. Further, when the SAT greatly decreases beyond the predetermined value α, the steering torque is increased so as to urge the steering torque in the direction in which the tire grip returns, that is, in the direction of return.

  By setting the predetermined value α in this way, it is possible to limit the driver's steering wheel increase operation when the vehicle starts to slip, so that the vehicle can be prevented from becoming unstable, and the driver can Can be recognized easily, so that accurate steering of the steering wheel can be promoted.

  Furthermore, a seventh embodiment of the present invention will be described with reference to FIG.

  In the present embodiment, the current command value change amount calculation means is replaced with the assisted gain calculation unit 61 in the first embodiment of FIG. 3, the second embodiment of FIG. 4, the third embodiment of FIG. 6, and the fourth embodiment of FIG. 63 and an example of a division unit 71. The current command value I from the addition / subtraction unit 50A is input to the current command value change amount calculation unit 63, and the change amount ΔI of the current command value I calculated by the current command value change amount calculation unit 63 is input to the division unit 71. The change amount ΔTh of the steering torque Th calculated by the steering torque change amount calculation means 68 is input to the division unit 71, and the division result (= ΔI / ΔTh) in the division unit 71 is transferred to the transfer function unit (= Kt · G) 64. To the adder 67B. The division result of the change amount ΔI of the current command value I and the change amount ΔTh of the steering torque Th is obtained as a result of the first embodiment shown in FIG. 3, the second embodiment shown in FIG. 4, the third embodiment shown in FIG. Since it is configured as the calculation result Km of the assist gain calculation unit 61 in the embodiment, the same effect as in each of the embodiments can be obtained.

  Also, as shown in FIG. 16, the phase compensation means 81 is provided after the SAT estimation means 40, the phase compensation means 80 is provided after the transfer function part 66, or the phase compensation means 83 is provided as an assist gain calculation part. It is preferable to compensate for the phase difference caused by the SAT estimation means 40 in the subsequent stage of 61. This is because even if a steered wheel rotates and a lateral slip angle occurs in the steered wheel, there is a delay in generating a lateral force or SAT. This is to make it easier to predict the behavior. In addition, as shown in FIG. 17, the phase compensation means 80, 81, or 83 may predict and output the future value from the past value and the current value as phase advance compensation.

  Furthermore, a filter 82 for removing disturbance noise (for example, high frequency components from the road surface, noise of more than a dozen Hz) is provided in the previous stage of the assist gain calculation unit 61, or the filter 83 is provided in the subsequent stage of the assist gain calculation unit 61. By providing it on the surface, disturbance noise from the road surface can be reduced, and a more stable steering feeling can be obtained.

In addition, although it has shown linearly in the characteristic of FIG. 13, you may change like a quadratic curve. 3 may be provided before the SAT gain Ks is input to the multiplier 70 according to Equation 10, and the SAT estimated value SAT ^* from the STA estimating means 40 can be multiplied by the SAT gain Ks. It only has to be a result. In each of the above-described embodiments, the motor angular speed ω has been described. However, instead of the motor angular speed ω, a column shaft angular speed ω _A or a rack speed may be used.

It is a block diagram which shows the basic control system used as the premise of this invention. It is a characteristic view which shows the relationship between an assist gain and a ratio. It is a block diagram which shows 1st Example of this invention. It is a block diagram which shows 2nd Example of this invention. It is a characteristic view set according to a vehicle speed. It is a block diagram which shows 3rd Example of this invention. It is a characteristic view set according to angular velocity. It is a block diagram which shows 4th Example of this invention. It is a characteristic view which shows the change of SAT and the change rate of SAT. It is a characteristic view which sets steering torque based on SAT. It is a block diagram which shows 5th Example of this invention. It is a flowchart which shows the operation example of this invention (5th Example). It is a figure which shows the characteristic which adjusts a steering torque based on the variation | change_quantity of SAT and the variation | change_quantity of steering torque. It is a block diagram which shows 6th Example of this invention. It is a block diagram which shows 7th Example of this invention. It is a block diagram further explaining the structural example concerning this invention. It is a characteristic view which shows the example which performs the phase lag compensation which concerns on this invention. It is a figure which shows the structural example of the conventional steering device. It is a block diagram which shows the structural example of the control unit of the conventional steering apparatus. It is a schematic diagram which shows the mode of the torque generate | occur | produced from a road surface to a steering. It is a figure for demonstrating SAT generate | occur | produced on a front wheel. It is a characteristic view which shows the relationship between a slip angle, SAT, and lateral force. It is a figure which shows the slip area | region which generate | occur | produces in the direction of a tire, and a slip angle. It is a figure which shows the relationship between lateral force, a trail, and an adhesion area | region. It is a figure for demonstrating the change of an adhesion area | region using a triangular figure.

Explanation of symbols

1 Handle 2 Column shaft 10 Torque sensor 12 Vehicle speed sensor 20 Motor 30 Control unit 40 SAT estimation means 41, 54 Friction calculation unit 42 Q filter 43, 52 Gain units 44, 53, 64 Transfer function unit 55 Angular acceleration calculation unit 56 Angular velocity calculation Units 59 and 61 Assist map 60 F adjustment unit 62 F setting unit 63 Current command value change amount calculation unit 65A, 65B Constant unit 68 Steering torque change amount calculation unit 80 Increase / return determination unit

Claims (13)

In a control device for an electric power steering device that drives and controls a motor that applies assist torque to a steering system based on a current command value calculated based on steering torque and vehicle speed,
SAT estimation means for estimating SAT;
An assist gain calculator that calculates an assist gain that is a ratio of the assist torque and the steering torque;
; And a F adjusting means for setting the ratio of the change amount of the steering torque with respect to the amount of change in the SAT,
Wherein said assist gain obtained by the assist gain computation unit, on the basis of the ratio set in the F adjusting means obtains the SA T gain,
Based on the SA T gains obtained, wherein adjusting the SAT estimation value obtained by the SAT estimating means, the adjustment has been estimated SAT value and SAT feedback compensating value,
Control device for an electric power steering apparatus characterized by correcting the assist torque by the SAT feedback compensating value.   The control device for an electric power steering apparatus according to claim 1, wherein the ratio is set according to the vehicle speed.   2. The control device for an electric power steering apparatus according to claim 1, wherein the ratio is set in accordance with an angular velocity of the motor, a column angular velocity or a rack velocity.   2. The control device for an electric power steering apparatus according to claim 1, wherein the ratio is set in accordance with the estimated SAT value and the angular velocity of the motor, or the column angular velocity or the rack speed.   2. The control device for an electric power steering apparatus according to claim 1, wherein the ratio is set in accordance with the estimated SAT value and a determination signal for increasing / returning a steering wheel.   2. The ratio according to claim 1, wherein the ratio is set according to an angular velocity or a column angular velocity or a rack speed of the motor, the vehicle speed, the SAT estimated value, and a steering wheel increase / return determination signal. Control device for electric power steering device. The determination signal is at additional turning, the absolute value decreases the SAT estimated value, and when the absolute value of the change amount of the SA T is smaller than the predetermined value, the amount of change in the steering torque and the amount of change in the SAT The control device for an electric power steering apparatus according to claim 5 or 6 , wherein the ratio is set so as to have a positive correlation. The determination signal is at additional turning, the absolute value decreases the SAT estimated value, and when the absolute value of the change amount of the SA T is a predetermined value or more, the amount of change in the steering torque and the amount of change in the SAT The control device for an electric power steering apparatus according to claim 5 or 6 , wherein the ratio is set so as to have a negative correlation.   The control device for an electric power steering apparatus according to claim 7 or 8, wherein the predetermined value is changed by the vehicle speed, the motor angular velocity or the column angular velocity, or the vehicle speed and the motor angular velocity or the column angular velocity. The assist gain calculator is
Current command value change amount calculating means for calculating a change amount of the current command value;
By dividing the amount of change in the current command value with variation of the steering torque, control of the electric power steering device according to any one of claims 1 to 9 is constituted by a divider for calculating the assist gain apparatus.   The control device for an electric power steering apparatus according to any one of claims 1 to 10, wherein phase compensation means is provided at a stage subsequent to the SAT estimation means or a stage subsequent to the assist gain calculation unit.   12. The control device for an electric power steering apparatus according to claim 11, wherein the phase compensation means is phase advance compensation means for calculating a future compensation value based on a current value and a past value.   The control device for an electric power steering apparatus according to any one of claims 1 to 12, wherein a filter for removing high-frequency noise is provided at a subsequent stage or an upstream stage of the assist gain calculation unit.

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