JPH0797028B2 - Steering angle detector - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a steering angle detection device that detects a steering angle in a steering mechanism of a vehicle.

[Conventional technology]

As a conventional steering angle detecting device, there is, for example, a device previously filed by the applicant and described in JP-A-60-176804.

The steering angle detector outputs steering angle information according to the steering angle of the steering mechanism of the vehicle, and averaging processing means for averaging the steering angle information of the steering angle detector to calculate neutral position information. And a difference value calculation means for calculating a difference value between the neutral position information of the averaging processing means and the steering angle information of the steering angle detector. By calculating the neutral position information by averaging and detecting the steering angle based on the difference between the neutral position information and the current steering angle information, the mounting position of the steering angle detector to the steering mechanism can be freely selected. I have to.

[Problems to be solved by the invention]

However, in such a conventional steering angle detecting device, all the steering angle information including the steering angle information output from the steering angle detector by the averaging processing means when the steering wheel is turned is averaged. Since the right curve and the left curve do not always have the same frequency on the actual road surface and the turning radii are different, the steering angle information when turning the vehicle is averaged. In this case, for example, when the vehicle travels on a road where there are more right curves than left curves, the steering angle information on the right turn side increases, and the steering neutral position calculated by averaging these is the actual steering neutral position. There is a problem that accurate neutral position information cannot be obtained due to a large deviation from the position to the right turning side.

The present invention has been made by paying attention to such inadequate points of the related art, and determines whether or not the vehicle is in a turning state based on the steering torque information, so that the vehicle is in a straight running state where the steering wheel is not turned. An object of the present invention is to provide a steering angle detection device that obtains accurate neutral position information by executing an averaging process based on only steering angle information and calculating an average value of steering angles.

[Means for solving problems]

In order to solve the above-mentioned inadequate points, the present invention relates to a steering angle detection device for detecting a steering angle in a steering mechanism of a vehicle, as shown in the basic configuration diagram shown in FIG. A steering angle detector for outputting steering angle information, a steering torque detector for outputting steering torque information according to a steering torque applied to the steering mechanism, and a steering torque information within a predetermined range for a predetermined time. Stable state detecting means for detecting a continuous stable state; and averaging processing means for averaging steering angle information to calculate neutral position information when the stable state detecting means detects a stable state. A steering angle calculation means for calculating a difference value between the neutral position information of the averaging processing means and the steering angle information of the steering angle detector is provided.

[Action]

Thus, in the present invention, the steering angle of the steering mechanism is detected by the steering angle detector and the steering torque is detected by the steering torque detector, and the steering torque information continues within a predetermined range for a predetermined time. When a stable state is detected by the stable state detection means, the averaging processing means averages the steering angle detection values to calculate neutral position information, and the difference value between the neutral position information and the current steering angle information. By calculating the steering angle by the steering angle calculation means based on the above, the detection accuracy of the steering angle neutral position is improved.

〔Example〕

 Hereinafter, the present invention will be described based on illustrated embodiments.

2 to 9 are views showing an embodiment of the present invention.

First, the structure will be described. 1 shown in FIG. 2 is a steering shaft, a steering wheel 2 is attached to the upper end thereof, and a universal joint 3 is attached to the lower end thereof.
The pinion shaft 4 is connected via the pinion shaft 4. The pinion provided at the lower end of the pinion shaft 4 meshes with the rack of the rack shaft 6 inside the steering gear box 5. Further, tie rods 7,7 are provided on both ends of the rack shaft 6.
Are swingably connected to each other, and each tie rod 7,
Knuckles 9 that rotatably support front wheels 8 that are steered wheels are swingably connected to the outer ends of 7, respectively.

The steering wheel 2, the steering shaft 1, the universal joint 3, the pinion shaft 4, the rack shaft 6, the tie rods 7 and the knuckle 9 constitute a steering mechanism.

The pinion shaft 4 is connected to the rotating shaft of the electric motor 10 via a worm gear reduction mechanism. Electric motor
Reference numeral 10 is composed of, for example, a DC servo motor, and its rotational force is transmitted to the steering mechanism via the worm gear mechanism, whereby a steering assist force corresponding to the steering force is applied to the steering mechanism.

Further, the steering shaft 1 is associated with a steering angle detector 11 that detects a steering angle and outputs steering angle detection signals D1 and D2 as steering angle information according to the detected steering angle. An example of the steering angle detector 11 is, as shown in FIG. 3, fitted to the steering shaft 1 to rotate integrally with the steering shaft 1 and to form a plurality of slits at equal angular intervals on the outer peripheral portion.
It is composed of a slit disk 12 having 12a and a photo interrupter 13 facing each other across the slit disk 12. Here, the photo interrupter 13 is the slit.
There are two sets of light-emitting elements 14 and 15 and a light-receiving element (not shown in the figure) that face each other with 12a in between, and these are pitch P between slits 12a.
1/4 or an integral multiple thereof, and therefore, as shown in FIG.
The steering angle detection signals D1 and D2 which are out of phase with each other by 1/4 of the pitch P therebetween are output.

In this case, the steering direction of the steering mechanism can be detected by the phase shift direction of the steering angle detection signals D1 and D2. That is, the detection signal D1 changes from "0" (OFF) to "1" (O
When the detection signal D2 is “0” at the time of rising to N),
Alternatively, when the detection signal D2 is "1" at the time when the detection signal D1 falls from "1" to "0", it is determined to be right-turned, and in the opposite case, it is left-turned. It is decided.

Reference numeral 16 is a steering torque detector that is installed in association with the steering shaft 1 and detects a steering torque input to the steering shaft 1 and outputs a steering torque detection signal DT as steering torque information according to the detected steering torque. . The steering torque detector 16 is composed of, for example, a strain gauge fixed to the steering shaft 1. The steering torque detector 16 detects a twist generated in the steering shaft 1 when a driver steers the steering wheel 2, and determines the magnitude of the twist. The steering torque detection signal DT having the corresponding analog voltage is output.

Reference numeral 17 denotes a vehicle speed detector that detects the vehicle speed, for example, detects the rotation speed of the output shaft of the transmission and outputs a vehicle speed detection signal DV as vehicle speed information that is a pulse signal with a cycle corresponding to this.

The vehicle speed detection signal DV, the steering angle detection signals D1 and D2, and the steering torque detection signal DT are supplied to the control device 20, and the control device 20 executes arithmetic processing based on these input signals.

A drive circuit 18 and a power source 19 such as a battery are connected to the control device 20, and the main part thereof is as shown in FIG.
For example, it is configured by the microcomputer 21.
This microcomputer 21 has an interface circuit 2
2, the arithmetic processing unit 23 and a storage device 24 such as RAM, ROM, etc., and the steering angle detector 11, the interface circuit 22,
The steering torque detector 16 and the vehicle speed detector 17 are connected, and the electric motor 10 is connected via a drive circuit 18.

Further, the arithmetic processing unit 23 reads the steering angle detection signals D1 and D2, the steering torque detection signal DT and the vehicle speed detection signal DV via the interface circuit 22, and executes the arithmetic processing described later based on these. Further, the storage device 24 is an arithmetic processing unit.
A predetermined program required to execute the arithmetic processing of 23 is stored, and the arithmetic result of the arithmetic processing device 23 and the like are stored. The microcomputer 21, specifically, as shown in FIG. 6, also serves as the steering angle detecting section 25 and the assisting force calculating means 30 which is the drive control section of the electric motor 10.

The steering angle detector 25 receives the steering angle detection signal D from the steering angle detector 11.
Steering direction determining means 26 for determining the steering direction based on 1, D2
And a counting means 27 that counts up / down based on the determination result of the steering direction determining means 26, based on the count information of the counting means 27 and the steering torque detection signal DT that is the steering torque information of the steering torque detector 16. Therefore, when the detected steering torque value is less than a certain value, the count information, that is, the steering angle information θ ₀ is averaged every predetermined time, and the neutral position information θ indicating the neutral position of the steering mechanism when the vehicle travels in a straight traveling state is obtained. and averaging means 28 to calculate the _C, steering to calculate the steering angle information theta ₀ calculates the difference value by the steering angle detection information and theta neutral position information theta _C and counting means 27 of the averaging means 28 And angle calculation means 29.

In this case, the averaging processing means 28 sequentially averages the steering angle information θ ₀ of the counting means 27 to calculate an average value θ _N , which is used as neutral position information θ _C which represents the neutral position of the steering mechanism in a pseudo manner. The data is stored in a predetermined storage area of the storage device. Here, as a method of calculating the average value θ _N , for example, the following equation can be applied.

θ _N = α · θ _N-1 + β · θ _N (1) However, α + β = 1.

Further, since the steering angle calculation means 29 calculates the difference value between the neutral position information θ _C calculated by the averaging processing means 28 and the steering angle information θ ₀ of the counting means 27, the calculation result is the steering of the steering mechanism. The steering angle detection information θ represents the actual steering state considering the direction.

Further, the assisting force calculating means 30, the steering angle detection information θ from the steering angle detection unit 25, the steering torque information DT from the steering torque detector 16, and the vehicle speed information DV from the vehicle speed detector 17, When the steering torque information T is equal to or less than a preset predetermined steering torque reference value A and the vehicle speed information V is equal to or less than a preset predetermined vehicle speed reference value, that is, the steering operation is completed and the steering wheel is moved from the steering wheel. When returning to the straight traveling state by releasing the control signal, for example, a control signal CS having a logical value "1" for rotationally driving the electric motor 10 so as to return the steering mechanism to the neutral position where the steering angle θ becomes 0 is supplied to the interface circuit 22. And to the electric motor 10 via the drive circuit 18.

Next, the processing procedure of the microcomputer 21 will be described as follows.
It will be described with reference to FIGS.

That is, the microcomputer 21 normally executes another main program, and when the steering angle detection signals D1 and D2 of the steering angle detector 11 are input to the interface circuit 22, for example, at the time of rising of them, the main The program is interrupted to execute the steering direction determination interrupt processing shown in FIG.

In this interrupt process, the steering angle detection signal D
1 and D2 are read, and in the next step, it is determined whether or not the detection signal D1 is "1". As a result of the determination, when the detection signal D1 is "1", the process proceeds to step and it is determined whether the steering angle detection signal D2 is "0". As a result of the determination, when the detection signal D2 is “0”, the process proceeds to step and the counting means 27 is counted up by “1”, while when the detection signal D2 is “1”, After shifting to the step and counting down the counting means 27 by "1", each returns to the main program.

If the result of the determination in step is that the detection signal D1 is “0”, the process moves to step and it is determined whether or not the detection signal D2 is “1” and the detection signal D2 is “1”. If the detection signal D2 is "0", the process is returned to the main program.

Here, the steering direction determination means 26 is configured by the processing of steps and and and the counting means 27 is configured by the processing of steps and.

Next, when the steering angle calculation interrupt processing shown in FIG. 8 is executed at intervals of a predetermined time (for example, 100 msec) with respect to a predetermined main program set in advance, first, the steering torque detection signal is output in step. DT is read, and in the next step, it is determined whether or not the absolute value | T | of the steering torque detection value T is less than or equal to a preset steering torque reference value A. As a result of the determination, when the absolute value | T | is larger than the reference value A, it is determined that steering is in progress, the process proceeds to step, and a preset constant time for performing the average calculation of the steering angle information is set. The timer to be managed is reset, and the timer interrupt processing is ended by this, and the main program is restored.

On the other hand, if the determination result of the step is | T | ≦ A, the process proceeds to step, and it is determined whether or not the timer is set. If not, the process proceeds to step and the timer After setting, move to step, while if already set, move directly to step. In this step, the timer value, which is the content of the timer, is set to a predetermined reference time B set in advance.
It is determined whether or not the above. As a result of the determination, when the timer value is less than the reference time B, the timer interrupt processing is ended by this and the main program is restored, while when the timer value is the reference time B or more, the process proceeds to step.

In this step, the steering angle averaging process described below is executed, and in the next step, the steering angle calculation process described below is similarly executed, and then the process proceeds to step to reset the timer and then the main Return to the program.
Here, the processing of steps S11 to S15 corresponds to the stable state detecting means.

In the averaging process of the above steps and the steering angle calculating process of the steps, as shown in FIG. 9, first, in step A, the neutral position information θ _C represented by the average value which is the calculation result of the averaging processing means 28 is obtained. reading, then in step B by calculating _{(θ-θ 0/100)} , temporarily stored in a predetermined storage area of the storage device the operation result as theta _C. Then control proceeds to step C, reads the count value theta ₀ of counting means 27, then, calculates in step D the (θ _0/100) in a predetermined storage area of the storage device the operation result as theta _N Store temporarily.

Then, the process proceeds to step E, where θ _C and θ _N stored in steps B and D are read and added, and the result is taken as θ _C. Next, the process proceeds to step F, and the calculation result of step E is stored in a predetermined storage area of the storage device as new neutral position information θ _C.

Next, the process proceeds to step A, the neutral position information θ _C stored in step F and the count value θ ₀ of the counting means 27 are read out, (θ _C −θ ₀ ) is calculated, and the calculation result is steered. The angle detection information θ is stored in a predetermined storage area of the storage device and then the main program is restored.

Here, the processing of steps A to F constitutes the averaging processing means, and the processing of steps A and B constitutes the steering angle calculation means.

Next, the operation will be described.

Now, assuming that the vehicle is in a turning traveling state and the steering mechanism is being steered or is being held at a certain steering angle, the steering force T or the steering force is equal to or greater than a reference value A. , The averaging process is not performed as shown in FIG. Therefore, the averaging processing means 28 does not read the steering angle information θ ₀ of the counting circuit 27 and maintains the neutral position information θ _C that is the previous average value. Therefore, in this state, the steering direction determination means 26 and the counting means 27 are operated,
The steering angle information θ ₀ of the counting means 27 is the steering wheel 2
However, since the neutral position information θ _C is not updated, the neutral position information θ _C does not inadvertently deviate from the actual position of the steering wheel 2.

When the driver returns the steering wheel 2 to the straight traveling state by finishing the turning from these states and the steering torque information T thereof falls below the reference value A, the averaging processing means 28 is operated and the eighth, The average value calculation interrupt process shown in Fig. 9 will be executed. As a result, the equation (1) is calculated, and the average value at that time is stored in the storage device as the neutral position information θ _C. Neutral position information θ in this case
_{Since C} is an average of the steering angles when the steering wheel is not turned, it has a value that substantially coincides with the neutral position of the steering mechanism when the vehicle actually travels straight.

Thus, in this embodiment, the steering torque value is used to determine whether the steering wheel is turned, and the steering angle detection values when the steering wheel is not turned are averaged to detect the steering angle. The neutral position can be detected with high accuracy by reducing the number, and for example, even if the size and frequency of the right curve and the left curve are different, the problem that the neutral position is displaced can be eliminated.

10 to 12 are flowcharts showing other examples of the steering angle calculation processing by the calculation processing device 23, respectively.

The flow chart shown in FIG. 10 is obtained by removing steps from the flow chart shown in FIG. 8. In this case, the average number of times increases, so that the detection accuracy of the neutral position can be further improved.

The flowchart shown in FIG. 11 is such that the state where the hand is released from the steering wheel 2 is also corrected during the steering operation. Therefore, while the steps in the flowchart of FIG. After that, steps are provided. That is, the step determines whether or not the detected torque absolute value | T | of the steering torque information T is a value close to 0, and when the determination result of this step is | T | ≈0, the process proceeds to the step. Then, after setting the timer, the process proceeds to step, while the judgment result of the step is | T |
When ≠ 0, the process directly goes to the step to determine whether the value of the timer is the second reference time C or more.

In the case of this embodiment, since the steering angle information when the steering wheel is released during steering for a short time is also ignored, the steering angle detection error can be made smaller even if the steering wheel is released.

Further, the flowchart shown in FIG. 12 is such that when the interrupt processing is started, the averaging operation is executed immediately after that, and in this case, since the number of processing steps is small, this steering angle The ratio of the operating time of the microcomputer 21 occupied by the arithmetic processing can be reduced, and other calculations can be performed correspondingly. Therefore, the microcomputer 21 can have a margin.

In the above embodiment, the averaging processing means 28 performs averaging based on the equation (1) every time the steering angle information θ ₀ of the counting means 27 is read, but the invention is not limited to this. Instead, the steering angle information θ ₀ of the counting means 27 is stored in the storage device 24 while being sequentially updated by a predetermined number, and each steering angle information stored in the storage device 24 is simply averaged to calculate an average value. Good.

Further, in the above embodiment, the case where the photo interrupter 13 is applied as the steering angle detector 11 has been described, but not limited to this, a steering angle detector that generates a voltage or other analog detection signal according to the steering angle of the potentiometer or the like. Alternatively, the detection signal may be A / D converted and supplied to the microcomputer 21, and the digital detection data may be averaged. In this case, the steering direction determination means 26 and the counting means 27 can be omitted.

〔The invention's effect〕

As described above, according to the present invention, the steering angle detector, the steering torque detector, and the stable state in which the steering torque information is in the stable state in which the steering torque information continues within the preset predetermined range for the predetermined time Detecting means, averaging processing means for averaging the steering angle information to detect neutral position information when the stable state detecting means detects a stable state; and a difference value between the neutral position information and the steering angle information. Since the steering angle detector is configured to include the steering angle calculation means for calculating, the neutral position information is calculated only when the steering torque information is in a stable state that continues within a predetermined range for a predetermined time. Therefore, the steering neutral position can be detected with high accuracy without being affected by steering assembly error, left-right wheel difference in toe-in amount, tire unicity, price tear, and the like. The effect is obtained that there is no possibility that even the neutral position is displaced If you have made a case and slalom runs that differ in size and frequency of the curve and left curve.

[Brief description of drawings]

FIG. 1 is a block diagram showing the basic configuration of the present invention, FIG. 2 is a schematic configuration diagram showing an embodiment of the present invention, FIG. 3 is a plan view showing an example of a steering angle detector, and FIG. FIG. 5 is a signal waveform diagram showing a detection signal, FIG. 5 is a block diagram showing a control device according to the present invention, FIG. 6 is a block diagram showing a concrete configuration of the same microcomputer, and FIGS. It is a flow chart which shows a processing procedure, respectively. 1 ... Steering shaft, 2 ... Steering wheel, 10 ... Electric motor, 11 ... Steering angle detector, 16 ... Steering torque detector, 20 ... Control device, 21 ... Microcomputer, 22 ... Interface circuit , 23 ... arithmetic processing device, 24 ... storage device, 25 ... steering angle detecting section, 26 ... steering direction determining means, 27 ... counting means, 28 ... averaging processing means, 29 ... steering angle calculation means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yutaka Aoyama, 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. 72) Inventor Satoshi Norinori Nissan Motor Co., Ltd. 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa (56) Reference JP-A-61-28811 (JP, A)

Claims (1)

[Claims] 1. A steering angle detecting device for detecting a steering angle in a steering mechanism of a vehicle, and a steering angle detector for outputting steering angle information according to a steering angle of the steering mechanism, and steering provided to the steering mechanism. A steering torque detector that outputs steering torque information according to torque, a stable state detection unit that detects that the steering torque information is in a stable state that continues within a preset predetermined range for a predetermined time, and the stable state detection unit And averaging means for calculating the neutral position information by averaging the steering angle information when it is detected that the steering angle information is stable, and the neutral position information of the averaging means and the steering angle information of the steering angle detector. And a steering angle calculation means for calculating a difference value between the steering angle detection device and the steering angle detection device.