JP2748428B2 - Vehicle steering force control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle steering force control device, and more particularly to an improvement of a vehicle steering force control device that finely controls a steering assist force according to a traveling state.

(Prior Art) Generally, if the steering force of an automobile is low at low speeds, the handling effort of the vehicle can be saved, and on the other hand, when the vehicle is running at high speeds, a somewhat heavy steering force is preferable in terms of running stability.

The so-called power steering device, in which a steering assist force generating mechanism is added to the steering device, is effective in reducing the former low-speed steering force, but tends to reduce the steering force even at a high speed, and there is a problem in terms of compatibility. . Therefore, the steering assist force is controlled according to the traveling state.

As a conventional steering force control device for a vehicle of this type, for example, there is a device described in Japanese Patent Application Laid-Open No. 62-149558.
In this apparatus, a first travel index indicating a road condition such as whether a vehicle is traveling on a mountain road or an urban area is calculated from a variation in a steering wheel steering angle signal, and at the same time, a driver is impatient from the frequency of acceleration / deceleration. A second running index indicating a driving situation of the driver, such as whether the vehicle is driving or a gentle driving, is calculated, and control is applied to the steering assist force control means from the first and second running indexes. The current is determined to obtain a steering assist force according to the road condition and the driving condition.

 Specifically, the first travel index Kθ is obtained according to the following equation: Kθ = D / i where D: the frequency of occurrence of a predetermined steering tendency i: the number of samplings The second travel index Kv is calculated according to the following equation: I'm asking.

However, Dn: D ₁ to D Incidentally buffer register data for storing vehicle speed data to _L, as documents describing the thing similar, JP 59
JP-A-118575 and JP-A-61-257365.

(Problems to be Solved by the Invention) However, in such a conventional vehicle steering force control device, specific signals among various parameter signals indicating a running state, that is, a steering wheel steering angle signal and a vehicle speed signal are used. Is used to execute a preset arithmetic expression (formula) and detect a road condition and a driving condition from the processing result. However, there has been a problem that both the driver and the driver who prefer gentle driving cannot be given a satisfactory steering feeling.

That is, it is not easy to observe the driver's steering tendency at any time of travel and to determine unambiguously whether the driver's preference is sports-oriented or gentle driving. A driver who likes the vehicle does not always travel like that. Therefore, even if the road condition and driving condition are detected based on little information such as steering tendency and vehicle speed, it is only a representative one, so it is not possible to obtain a steering feeling that matches each driver. It is very difficult.

(Object of the Invention) Therefore, an object of the present invention is to obtain a steering feeling that is matched to each driver by applying the associatron to sequentially grow and change the control characteristics.

(Means for Solving the Problem) In order to achieve the above object, a vehicle steering force control apparatus according to the present invention has a basic conceptual diagram as shown in FIG. Detecting means a, input means b for inputting a characteristic signal indicating a steering characteristic desired by the driver by the driver, and each being assigned to each of the parameters and characteristic signals, and the contents of each parameter and characteristic signal A large number of nerve cell elements c whose states can be changed according to the above, and a connection between each pair of nerve cell elements c, transmitting the state of one nerve cell element c to the other nerve cell element c, Changing the state of each nerve cell element c according to a transmission element d that changes a coupling coefficient according to the state, and an output of the parameter detection means a and an output of the input means b; A patterning means e for patterning and memorizing various parameters and characteristic signals representing a traveling state at an arbitrary time point, and when at least a part of the parameter signals are inputted, a pattern including the characteristic signal is referred to by referring to the pattern. Recall means f to be reproduced
Calculating means g for calculating a control value of a steering assist force such that the steering characteristic desired by the driver is obtained in accordance with the pattern reproduced by the recall means f; and an assist force of the steering device according to a signal from the calculating means g. Operating means h for operating the generating mechanism.

(Action) In the present invention, by changing the state of a large number of neuronal elements,
An information pattern corresponding to a driving state including a characteristic signal of a steering characteristic desired by the driver is created, and then the information pattern is referred to according to various parameters during actual driving. When the actual traveling state matches the information pattern including the characteristic signal, it is determined that the vehicle is under the traveling state of the steering characteristic desired by the driver, and the assist force generation mechanism of the steering device is operated.

The creation of the information pattern described above is performed as a so-called “memorizing” operation in the associatron, and the determination is also performed as a “recall” operation in the associatron. Here, an overview of associatron
Associatron is an associative memory model (modeling the neural circuit of the brain) proposed by Assistant Professor Nakano of the University of Tokyo. Conceptually, as shown in Fig. 2, many neurons (neurons) Xi And a nerve fiber and a synapse (hereinafter, a joint Mij) connecting these neurons. Each neuron Xi can take three states (1, 0, -1) by an external input, and the connected body Mij transmits the state of each neuron Xi to another connected neuron Xi. FIG. 3 shows an equivalent circuit of an associatron having such a structure.
That is, in FIG. 3, nodes N _{1 to} N ₄ are neurons.
Corresponds to Xi, the resistor R ₁ to R ₆ corresponds to conjugate Mij. The potential E generated at _one node (for example, N ₁ )
The other node N ₂ is connected via _three resistors R _{1 to} R ₃ connected to N _1.
To to N _3, the predetermined transmission coefficient (corresponding to the size of the R ₁ to R ₃₎
, And one tendency appears in the potential patterns of all the nodes N _{1 to} N ₄ . Now, consider a 5 × 5 neuron structure as shown in FIG. Each neuron grant code to X ₁ to X _25. By giving an input to this neuron structure, an excitation pattern of "1" pattern as shown in FIG. 5 (a), an excitation pattern of "4" pattern as shown in FIG.
An excitement pattern having a “T” pattern as shown in FIG. When a partially missing pattern as shown in FIG. 6 is given as a recollection input, the neuron structure becomes the closest one of the previously stored FIGS. 5 (a) to 5 (c) from this pattern. Is recalled by association. That is,
In this case, X ₁₂ , X ₁₈ , and X ₂₄ are inverted to black, and a correct “4” pattern is recalled. Therefore, if, in correspondence with to X ₁ to X ₂₀ in various parameters representing the running state of the vehicle, also,
The X ₂₄ specific steering characteristic (e.g., reduced to a steering assist force) when made to correspond to, when the combination of X ₁ to X _20, for example, "4" near the pattern is, X ₂₄ is is inverted in black,
That is, it is determined that the state of X ₂₄ to the running state to be changed to a specific steering characteristic. Moreover, such a recall is performed, for example, accurately even when the parameter corresponding to X ₁₂ is missing, the accuracy of the determination, even if there is a disturbance in the parameter due to noise or the like is not lost.

Hereinafter, the present invention will be described with reference to the drawings.

7 to 11 are views showing one embodiment of a vehicle steering force control device according to the present invention.

First, the configuration will be described. 7, reference numeral 1 denotes a sensor group. The sensor group 1 includes a steering angle sensor 2 for detecting a steering angle St of a steering wheel, an engine speed sensor 3 for detecting an engine speed N, and a throttle pedal. And a vehicle speed sensor 5 for detecting a vehicle speed V.

Reference numeral 6 denotes a fine / integral operation circuit group. The fine / integral operation circuit group 6 has one integral operation unit 7 and four differential operation units 8 to 11, and the integral operation unit 7 is provided for each unit time T. Cumulative value S of St
t ", and the differential calculators 8 to 11 are respectively St, N,
First order difference value S corresponding to the amount of change in θ and V per unit time T
Find t ', N', θ ', V'. The sensor group 1 and the calculus / integration operation circuit group 6 include various parameters indicating the running state of the vehicle (that is, in this embodiment, St, St ', St ",
N, N ', θ, θ', V, V '). Note that the various parameters are not limited to the above examples, and may include, for example, wiper operation information and road surface friction coefficient information in order to know that the vehicle is traveling on rainy weather. This is because it is preferable that the steering force is higher on a wet road surface or a snowy road from the viewpoint of safety. Reference numeral 12 denotes a timer for outputting a signal indicating a unit time T every predetermined time, and 13 denotes a switch (input means) arbitrarily operated by a driver. The switch 13 is provided near the driver's seat. The dedicated one used is used. The switch 13 can be switched by the driver to, for example, two positions. When the switch 13 is in one of the two positions, "SPORT"
When it is at the other position, it outputs two command signals CMD "TOWN". For example, such a switch 13 is set to “SPORT” when a heavy steering force (that is, a small assist force) is desired by the driver, and is set to “TOWN” when other or a light steering force is desired. To be.

Reference numeral 14 denotes a control unit. The control unit 14 includes a section divider 14a and an associatron unit 14b, and has functions as a storage unit, a nerve cell element, a transmission element, a recall unit, and a calculation unit.
The associatron unit 14b is composed of, for example, a microcomputer, and the microcomputer includes a storage device such as a RAM and a ROM and a CPU. The ROM stores a program described below for performing the memorizing process and the recalling process. Predetermined array variables [array variables X (I) for storing running state parameters, array variables M (I, J) for storing coupling coefficients] are secured in the RAM as the above program is executed by the CPU. ing.

That is, each cell of X (I) corresponds to one of the neurons of the associatron, and the value stored in M (I, J) corresponds to the coupling coefficient Mij between Xi and Xj. . In addition,
i is each cell number. When the nerve cell is an N × N matrix, the maximum value of i is N ² . In addition, j represents i of the connection destination. When the CMD from the switch 13 is “SPORT”, the associatron unit 14b transmits the parameter “SPORT” and each parameter S divided by the section divider 14a.
t, St ′, St ″, N, N ′, θ, θ ′, V, V ′
X (I), and the "SPORT" and the coupling coefficient between each X (I) cell corresponding to the state of each parameter are stored in M (I, J), and the so-called "memorization" is stored. Do. Note that the memorization is also performed when the CMD is “TOWN”.
As a result of the memorization process, the parameter patterns corresponding to the various driving states are repeatedly recorded, and the coupling coefficient is also updated.

On the other hand, after the memorizing process, the process proceeds to the recalling process, and the above-described memorized pattern is recalled associatively in accordance with various parameters representing the driving state. In this recall process,
Even if some parameters are missing, it is recalled that the missing part is reproduced from the pattern of the other parameters. For example, even when the CMD is not “SPORT”, if the status of various parameters is similar to the case where the memorization was first performed in association with “SPORT”, a response is made as if “SPORT” was input. In other words, if the driving condition that requires “SPORT” is stored in a pattern in the memorization process and then stored, then a response of “SPORT” can be obtained associatively simply by inputting the relevant recall pattern. There is no need for the driver to operate the switch 13. For this reason, for example, a switch
If 13 is designated as SPORT → "large steering force (small assist)", it is determined that the steering characteristics need to be increased each time the corresponding pattern is input. The associatron unit 14b makes such a determination, calculates a control value that changes the steering characteristics according to this determination, and outputs an operation command signal Ss. Reference numeral 15 denotes an electronic control power steering (EPS) controller (hereinafter, EPS controller). The EPS controller 15 has a function as an operation means, and drives a PS solenoid valve (described later) of the steering device according to the operation command signal Ss. Generates and outputs a drive signal Sv.

FIG. 8 is a main part configuration diagram showing an example of the steering device. In FIG. 8, the rack shaft 21 is displaced in the vehicle width direction by the rotation of the pinion shaft 20 in response to the operation of the steering handle. At this time, the road surface reaction force from the steered wheels is changed in the direction in which the rack shaft 21 Is input to Then, the lever 22 attached to the pinion shaft 20 is tilted by the road surface reaction force to move the spool valve 24 in the control valve 23, and the movement of the spool valve 24 causes the high pressure oil circuit connected to the oil pump 25. 26 is the left and right cylinder circuit
27 and 28, and the other is connected to a drain side circuit 29. That is, when the spool valve 24 moves due to the road surface reaction force, a high oil pressure acts on one end surface of the power piston 30 fixed to the rack shaft 21, and a force (steering assist force) in a direction to cancel the road surface reaction force is generated. The magnitude of this steering assist force is determined by the amount of movement (valve stroke) of the spool valve 24,
The greater the road surface reaction force acting on 21, the greater the steering assist force.

On the other hand, to the reaction chambers 31 and 32 on the left and right sides of the spool valve 24, a hydraulic pressure Pa whose pressure has been reduced is guided via a fixed throttle 33, and the magnitude of the hydraulic pressure Pa and the reaction Due to the spring forces of the force springs 34 and 35, a force for pushing the spool valve 24 back to the neutral position is generated. The magnitude of Pa changes according to the valve opening of the variable throttle valve 36, and the valve opening of the variable throttle valve 36 is changed to a fully closed state or a fully opened state by a PS solenoid valve 37. That is, if the Sv from the EPS controller 15 corresponds to, for example, “SPORT”, the opening degree of the variable throttle valve 36 is fully closed by the PS solenoid valve 37, and Pa is supplied to the reaction force chambers 31 and 32. As a result, the force against the movement of the spool valve 24 is the sum of Pa and the spring force of the reaction force springs 34 and 35, and the valve stroke of the spool valve 24 is relatively small, so that the steering assist force is controlled to be small. You. That is, in this case, the steering force increases, and the driver can experience the road surface reaction force. Alternatively, if Sv corresponds to “TOWN”, the variable throttle valve 36 is fully opened, Pa is drained, and the valve stroke of the spool valve 24 increases,
The steering assist force is also increased, the steering force is lightened, and a light steering feeling can be obtained.

FIG. 9 is a flowchart showing a judgment processing program executed by the associatron unit 14b. Less than,
The processing operation will be described according to this flowchart. First, step (hereinafter, abbreviated as P) at P _1, CMD from the switch 13 to determine whether "SPORT" or "TOWN". For example, in the case of "SPORT", it is a case where the driver wishes to experience the road surface reaction force as a result of comprehensively judging the driving environment and the like, and in the case of "TOWN", he wants light handling. It is. That is, in the case of "SPORT", the driver desires a heavy steering force according to the road surface reaction force, and the traveling state at the time of the request is determined by various parameters (St, St ', S
t ", N, N ', θ, θ', V, in .P ₂ is correctly represented by V '), performs the memorization process by various parameters and SPORT at that time.

The memorization process is performed, for example, as shown in FIG.
For the array variable X (I). That is, each row of the array variable X (I) includes each parameter (V, V ′, θ,
θ ′, N, N ′, St, St ′, St ″), and each column corresponds to the value of each parameter. Here, each column directly corresponds to each value of the parameter. rather than, 11th membership as shown in FIG function (however, this figure is that. shown as a representative one corresponding to the vehicle speed V) is associated with the magnitude of the parameter on the horizontal axis of the L ₁ ~L ₇ The membership values Fk on the vertical axis are associated with each column because the parameters are directly associated with each column of the array, which requires a large number of arrays. There are problems such as an increase in the scale and hardware scale, and also a reduction in processing speed. By interposing a membership function between them, the above-mentioned problems do not occur, and simplification of the system and Improved processing speed can be achieved . Incidentally, L ₁ ~L ₇ each "very small in Figure 11, small, slightly small, usually,
A little big, big, very big ".

Note that a predetermined row of the variable array X (I) (for example,
The bottom line in the figure) is allocated for CMD, and 1
“SPORT” is assigned to one cell and “TOWN” is assigned to another cell. That is, in the case of “SPORT”, the membership value obtained from the value of each parameter at that time is stored in the cell of each row, and predetermined information (hereinafter, operation information HD) is assigned to the cell to which “SPORT” is assigned. Is stored. At the same time, in the associatron, an array M (I, J) for a coupling coefficient indicating the strength of connection between cells in the array X (I) is separately prepared.
J) stores each coupling coefficient in the case of “SPORT”. Then, when inputting the “SPORT” from the next time on, the X
The contents of (I) and M (I, J) are updated, and as a result, a memorized pattern of a running state that requires a heavy steering characteristic is constructed while gradually increasing the reliability. When such memorization process is performed once, then memorization counter CUNT e.g. +1 counts up at P ₃ (UP), P ₄
Then, the CUNT value is compared with the predetermined value L to determine whether or not the memorization process needs to be repeated thereafter. That is, since the reliability of the information pattern constructed by memorization depends on the magnitude of each accumulated coupling coefficient, the pattern performed based on actual vehicle information when a heavy steering characteristic is desired. The formation (that is, the memorization process) needs to be repeated at least until the coupling coefficient becomes a sufficient value. For this reason, a memorization counter is provided, and the counter value is set to a predetermined value L.
In the following, recall processing described later is not performed because of insufficient reliability. Therefore, not equal CUNT> L, i.e., when the lack reliability, so that again performs memorization process by repeating the P ₁ to P _6.

In the case where "TOWN" is judged in P _1, since the driver wishes to airy steering characteristic proceeds to P _5, and inspect the timer TMR which emits an ON signal every constant time, this TMR is ON
When, performing the memorization process in the case of light steering characteristics P _6. The memorization process at this time is also the same as the array variable X in FIG.
This is performed for (I), and the array variable M (I, J) for the coupling coefficient is also updated at the same time. In this case,
Since CMD is “TOWN”, “TOWN” at the bottom line of X (I)
Is stored in the cell assigned to... Which instructs to increase the steering assist force.

Here, a specific example of the storage process will be described. Array variable X
Assuming that the number of cells in (I) is n,
Put a C _1, C ₂ ...... Cn and number. Also, Ci (where i =
The state of 1, 2,... N is Xi, and Ci and Cj (where j =
1, 2,..., N), that is, the coupling coefficient is Mij. When nothing is stored in the cell, Mij
= 0. Now, a predetermined pattern X = (X ₁ , X ₂ ... Xn)
Is entered and Xi is 1 or-
Assuming that the value of 1 can be taken, the value of Mij is increased by 1 if Xi and Xj have the same sign, and decremented by 1 if Xi and Xj are different signs. If this is expressed by a mathematical expression, the following expression is obtained, which is a slightly modified expression of the so-called “Hebb's synapse strengthening rule”.

Mij ← Mij + Xi · Xj Hebb's law of synapse reinforcement is based on two cells (X (I)
Cells are excited at the same time, the connection between them is strengthened,
That is why it is widely accepted in the field of neurocomputing. In other words, the memorization process uses various parameters representing the driving state as an input pattern and strengthens the coupling coefficient according to the input pattern. If a pattern having the same tendency continues, the coupling coefficient is also strengthened with the same tendency. It is something to be done.

On the other hand, when CUNT> L is established by repeating the memorizing process and the pattern information worthy of reliability is constructed, the following recalling process is performed. First, various parameters in P ₇ St, St ', S
t ", N, N monitor ', theta, V, V' and, at P _8, performs a recall process was recalled enter these various parameters.
In the recall processing, for example, assuming that a recall input is X, a recall output y = (y ₁ , y ₂ ... Yn) for the recall input is obtained according to the following equation.

yi = φ (Mi ₁ · X ₁ + Mi ₂ · X ₂ + ... Mij · Xj + ... + Min · Xn) Here, φ (Z) is SGN of BASIC (basic) language.
As in the (sine) function, 1 is given to yi if the value of Z is positive, 0 if it is 0, and -1 if it is negative. That is,
The ith cell out of n is a coupling coefficient (Mi ₁ , Mi ₂ ... Min) between itself and all the other cells (X _{1 to} Xn) connected thereto.
Will reflect that state and change that state,
In other words, when a predetermined recollection input is given, an operation is performed so as to associatively reproduce the past recall pattern from the recall input and the previously stored coupling coefficient. As a result, for example, even if a recall input with some patterns missing is given,
A correct pattern can be reproduced from the missing pattern. Therefore, either (a) a recall input in which the bottom row of the array variable X (I) is missing, or (b) a recall input in which a part of the parameter representing the driving state is also missing in addition to (b). However, it is possible to recall a memorized pattern relating to heavy or light steering characteristics by supplementing the missing part. In the case of (a), if the state of various parameters representing the driving state corresponds to a heavy steering characteristic,
HD can be taken from the bottom line of X (I), and Ss can be output in accordance with the HD to instruct to reduce the steering assist force.

Also, in the case of (b), the steering characteristics corresponding to the running state can be determined in the same manner as described above, and some parameters are abnormal (for example, some parameter signals fail due to sensor failure or disconnection, etc.). ), The above determination operation can be performed without any trouble.

It is rarely considered that the steering characteristics determined in the recall process do not prompt the actual running state. As a method for coping with such a rare situation, for example, a cancel switch is provided in the driver's seat, and when the above-described rare situation occurs, when the cancel switch is operated, the recall process is stopped to force the recall process. The process may be shifted to the memorization process. More specifically, after the P ₈ in FIG. 9, put steps P ₉ to check the signals from the cancel switch, when the determination of P ₉ YES of (rare circumstances occurs), with P ₁₀
The CUNT greatly brought down, prompting determination NO of P _4, again P ₁
~P ₄ and may be repeated. In this way, new memorization is performed with various parameters in a rare situation, and the reliability of the recall processing can be restored.

Note that in P _9, when the cancel switch is not operated, since those results recall process matches the intention of the driver, and UP the CUNT at P _11, again repeat the subsequent P _7.

As described above, in the present embodiment, the memorization processing is executed in accordance with the actual driving state using the associatron, and the recall processing is executed to execute the specific driving state, that is, according to the road surface reaction force. The running state where the heavy steering characteristic is preferable and the running state where the light steering characteristic is preferable are automatically recognized. Therefore, the result of the automatic recognition matches the driver's preference, and a steering characteristic suitable for each driver's preference can be obtained.

In the above embodiment, the steering characteristics are set to "SPORT" and "TO
Although an example of switching to two stages of "WN" has been shown, the present invention is not limited to this. For example, it may be a multistage including "SPORT" and "TOWN", or may be changed continuously. Specifically, Sv applied to the PS solenoid valve 37
Is controlled in multiple stages or continuously, the opening of the variable throttle valve 36 can be set to a desired opening. Therefore, the magnitude of Pa supplied to the reaction force chambers 31 and 32 is changed in multiple stages or continuously, and the steering assist force can be set to a desired magnitude. In this case, it is needless to say that the switch 13 must be capable of extracting a multi-step or continuous signal.

Further, in the above embodiment, the steering assist force is controlled by changing the Pa supplied to the reaction force chambers 31 and 32.
As another function, for example, a bypass circuit may be provided between the high-pressure oil circuit 26 and the drain side circuit 29, and the flow passage area of the bypass circuit may be changed.

(Effects) According to the present invention, it is possible to perform variable control of the steering assist force according to the driving conditions while reflecting the driver's preference, and to obtain a steering characteristic suitable for each driver's preference. it can.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of the present invention, FIGS. 2 to 6 are diagrams for explaining an associatron, FIG. 2 is a structural conceptual diagram, FIG. 3 is an equivalent electric circuit diagram, and FIG. 5 (a), 5 (b) and 5 (c) are state diagrams each showing the memorized state, and FIG. 6 is a state diagram showing a state where an input for recall is given. . 7 to 11 are views showing an embodiment of a steering force control device for a vehicle according to the present invention. FIG. 7 is an overall configuration diagram, FIG. 8 is a configuration diagram of a main part of the steering device, FIG. 9 is a flowchart of the processing program, FIG. 10 is a conceptual diagram showing the arrangement state of the array variables, and FIG. 11 is a diagram showing the membership function. 1 ... sensor group (parameter detection means) 6 ... fine / integral operation circuit group (parameter detection means) 13 ... switch (input means) 14 ... control unit (neural cell element, transmission element, memorization) Means, recalling means, calculating means), 15 EPS controller (operating means).

Claims (1)

(57) [Claims] 1. a) parameter detecting means for detecting various parameters indicating a running state of a vehicle; b) input means for inputting a characteristic signal indicating a steering characteristic desired by the driver by the driver; c) A number of neural cell elements, each assigned to the respective parameter and characteristic signal, the state of which can be changed according to the content of each parameter and characteristic signal; d) coupling between each pair of neural cell elements And transmit the state of one neuron element to the other neuron element,
A transmission element that changes a coupling coefficient according to the state; and e) various parameters representing a running state at an arbitrary time point by changing a state of each nerve cell element according to an output of the parameter detection unit and an output of the input unit. And a patterning means for patterning and recording characteristic signals; and f) when at least some parameter signals are input,
Recall means for reproducing a pattern including a characteristic signal with reference to the pattern; and g) an operation for calculating a control value of a steering assist force to obtain a steering characteristic desired by the driver according to the pattern reproduced by the recall means. And h) operating means for operating the assist force generating mechanism of the steering device in accordance with a signal from the calculating means.