JP2850328B2 - Vehicle steering angle detection device - Google Patents

Abstract

PURPOSE:To correctly identify a neutral position by a method wherein if change in a steering angle is lower than the specified value for a specified period or longer while a vehicle is identified to be traveling straight, the steering angle is identified to be at the neutral position. CONSTITUTION:On the basis of the results detected by a steering status detecting device M1, a steering angle calculating device M2 calculates a steering angle and inputs it to a steering neutral position identifying device M5. On the other hand, on the basis of the results detected by a travel status detecting device M3, a straight travel detecting device M4 identifies a status of straight travel and inputs to the steering neutral position identifying device M5. Said identifying device M5 identifies the vehicle to be at the steering angle neutral position if change in the steering angle is lower than the specified value for a specified period or longer within the time while the vehicle is traveling straight. Since the steering angle specified from the detected steering status is compensated according to the change in the steering angle while the vehicle is continuously traveling straight, identification that the steering angle is at the steering neutral position can be correctly attained.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle steering angle detection device effective for detecting that a vehicle steering angle is at a steering neutral position.

2. Description of the Related Art A technique for accurately detecting a steering angle of a vehicle when performing a posture control, a braking control, or the like of the vehicle is conventionally known. As such a device, for example, a "vehicle steering angle detecting device" (Japanese Patent Laid-Open No. 60-176804) has been proposed. That is, the neutral position information is calculated by averaging the relative change amount of the steering angle detector that detects the steering of the steering mechanism, and the steering angle is detected based on the difference value between the neutral position information and the current steering angle information. Technology.

[Problems to be Solved by the Invention] In the related art, steering angle information is obtained from a steering direction and a steering amount based on a detection signal of a steering angle detector, and the steering angle information is obtained for each predetermined traveling distance of the vehicle. A configuration was adopted in which the neutral position of the steering angle was calculated by sampling and averaging. However, for example, when the vehicle is in a steady circular turning state over a predetermined traveling distance, the calculated neutral position of the steering angle asymptotically approaches the steering angle during the steady circular turning, and the accurate neutral position is determined. There was a problem that detection was not possible and an erroneous determination was caused.

Further, if a function of generating a steering neutral position identification signal corresponding to the neutral position of the steering angle is added to the steering angle detector, the configuration of the device becomes complicated, and the accuracy of mechanical attachment to the steering mechanism needs to be increased. Therefore, it is necessary to add a functional part dedicated to the neutral position detection, and there is a problem that reliability is reduced.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a vehicle steering angle detection device capable of accurately identifying a steering neutral position with a simple configuration without adding a function of generating a neutral position identification signal to a steering angle detector. .

Means for Solving the Problems According to the present invention, which has been made to achieve the above object, as shown in FIG. 1, a steering state detecting means M1 for detecting a steering state of a vehicle, and the steering state detecting means Steering angle calculating means M2 for calculating the steering angle of the vehicle based on the detection result of M1, and running state detecting means M3 for detecting the running state of the vehicle
A straight traveling state determining means M4 for determining whether or not the vehicle is in a straight traveling state based on the detection result of the traveling state detecting means M3; and a straight traveling state of the vehicle by the straight traveling state determining means M4. During the period in which the steering angle is determined to be in the state, continuously for a predetermined time or more, and when the change in the steering angle calculated by the steering angle calculation means M2 is equal to or less than a predetermined value, it is determined that the steering angle is in the steering neutral position. And a steering neutral position identification device M5 for identifying the vehicle.

[Operation] In the vehicle steering angle detecting device of the present invention, as illustrated in FIG. 1, the steering angle calculating means M2 calculates the steering angle of the vehicle based on the steering state of the vehicle detected by the steering state detecting means M1. calculate. Further, based on the running state of the vehicle detected by the running state detecting means M3, the straight running state determining means M4 determines whether or not the vehicle is in a straight running state. Here, during a period in which the vehicle is determined to be in the straight traveling state by the straight traveling state determination means M4, the change in the steering angle calculated by the steering angle calculation means M2 is continued for a predetermined time or more, and is not more than a predetermined value. In some cases, the steering neutral position identification means M5 serves to identify that the steering angle is at the steering neutral position.

That is, based on the running state of the vehicle, during a period in which it is determined that the vehicle is in the straight running state, when the change in the steering angle obtained from the detected steering state continues for a predetermined time or more and is equal to or less than a predetermined value, the vehicle Therefore, the vehicle steering angle detecting device of the present invention determines the steering angle determined from the detected steering state according to the change in the steering angle during the straight running state. And works to accurately identify the steering neutral position.

[Embodiment] Next, a preferred embodiment of the present invention will be described in detail with reference to the drawings. FIG. 2 shows a system configuration of a brake control device having a steering neutral position detecting function according to an embodiment of the present invention.

As shown in the figure, a braking control device 1 includes a steering angle sensor 2 that detects a steering angle of a vehicle and outputs a detection signal, a steering signal processing device 3 that calculates a steering angle from the detection signal of the steering angle sensor 2, Wheel speed sensors 4, 5, 6, 7 that detect the rotation speed of each wheel 4a, 5a, 6a, 7a of the vehicle and output wheel speed signals, and an electronic control unit (hereinafter simply referred to as ECU) for centrally controlling these wheel speed sensors 8).

The brake control device 1 also includes a master cylinder 9 that generates a hydraulic pressure according to the amount of depression of the brake pedal 9a, a brake hydraulic actuator 10 that adjusts the hydraulic pressure of the master cylinder 9 under the control of the ECU 8, Each wheel by the supply and discharge of
Wheel cylinders 4b, 5b, 6b, 7b for applying a braking force by 4a, 5a, 6a, 7a are provided.

Further, the brake control device 1 includes, as detectors, a brake switch 11 for detecting operation of a brake pedal 11, a vehicle speed sensor 12 for detecting a vehicle speed, a lateral acceleration sensor 13 for detecting a lateral acceleration acting on the vehicle, and a yaw rate acting on the vehicle. Is provided.

As shown in FIG. 3, the steering angle sensor 2 is press-fitted into the steering shaft 21, and is disposed at a position sandwiching the slit plate 23 having slits 22 formed at equal intervals over the entire circumference. It comprises two sets of photointerrupters 2a and 2b. Both photo interrupters 2a and 2b include light emitting diodes 24a and 25a and phototransistors 24b and 25b. When the slit plate 23 blocks and transmits the optical path of the photo interrupters 2a and 2b with the rotation of the steering shaft 21, the steering angle sensor detects a phase shift by a phase difference determined according to the arrangement position of the photo interrupters 2a and 2b. A signal is output. Therefore, as shown in FIG. 4, the operation angle sensor first detection signal SS1 and the steering angle sensor second detection signal SS2
, The steering direction and the steering amount can be detected.

The steering angle sensor first detection signal SS1 and the steering angle sensor second detection signal SS2 are input to the steering signal processing device 3 shown in FIG. The steering signal processing device 3 includes a CPU 3a, a ROM 3b, a RA
It is configured as a logic operation circuit around M3c,
It is connected to the input unit 3e and the input / output unit 3f via d, and performs input / output with the outside. The steering angle sensor first detection signal SS1 and the steering angle sensor second detection signal SS2 output from the steering angle sensor 2 are input via an input unit 3e, while transmission signals from the ECU 8 are input / output units.
Each is input to the CPU 3a via 3f. On the other hand, the CPU 3a
The transmission signal is output to the ECU 8 via the input / output unit 3f.

Further, the transmission signal of the steering signal processing device 3 and the detection signals of the respective sensors and switches are input to the ECU 8. ECU8, CPU8
a, a ROM 8b, a RAM 8c, and a backup RAM 8d as a logical operation circuit, and the input / output unit 8 via a common bus 8e.
f, connected to the output unit 8g for input / output with the outside. The wheel speed signals detected by the wheel speed sensors 4, 5, 6, 7 are transmitted to the steering signal processor 3 via the waveform shaping circuit 8h and the input / output unit 8f.
The transmission signal of the vehicle, the detection signals of the vehicle speed sensor 12, the lateral acceleration sensor 13, and the yaw rate sensor 14 are transmitted via the input / output unit 8f to the respective CPs.
Input to U8a. On the other hand, the CPU 8a transmits a transmission signal to the steering signal processing device 3 via the input / output unit 8f, and outputs the transmission signal to the output unit 8g and the driving circuit.
A control signal is output to the brake hydraulic actuator 10 via 8i.

Next, the steering angle detection processing executed by the steering signal processing device 3 will be described with reference to the flowchart shown in FIG. The present steering angle detection process is executed when the steering signal processing device 3 is started. First, in step 100, initialization processing such as resetting a counter C for calculating a steering angle to a value of 0 is performed. In the following step 105, the steering angle sensor first detection signal SS1 (n-1) in the previous processing, the steering angle sensor second detection signal SS2 (n-1) in the previous processing, and the steering angle sensor first signal in the current processing. A process is performed to reset all the detection signal SS (n) and the steering angle sensor second detection signal SS (n) at the time of this process to the value 0. Next, the routine proceeds to step 110, where a process of reading the steering angle neutral position signal SC transmitted from the ECU 8 is performed as described later. In the following step 115, it is determined whether or not the steering neutral position signal SC has a value of 1. If an affirmative determination is made, the process proceeds to step 120;
Then, go to each. Here, the steering neutral position signal SC is set to a value of 1 when the steering angle is at the steering neutral position, and is set to another value when the steering angle is not at the steering neutral position. Step 120 executed when the steering angle is in the steering neutral position
Then, after performing the process of resetting the counter C to 0, the process proceeds to step 125. In step 125, a process of reading the steering angle sensor first detection signal SS1 (n) in the current processing and the steering angle sensor second detection signal SS2 (n) in the current processing is performed. In the following step 130, the stored steering angle sensor first detection signal SS1 (n-
1), the steering angle sensor second detection signal SS2 (n
-1) According to the steering angle sensor first detection signal SS1 (n) at the time of the current processing read in step 125 and the steering angle sensor second detection signal SS2 (n) at the time of the current processing, it is stored in the ROM 3b in advance. A process for calculating an added value CI of the counter tail C is performed according to the map shown in FIG. The value of the added value CI indicates the steering amount, and the positive and negative signs indicate the steering direction, respectively. Next, the routine proceeds to step 135, where the count value of the counter C is set to step 1
A process of adding the addition value CI calculated in 30 and updating the count value of the counter C is performed. In the following step 140, a guard process for preventing overflow and underflow of the count value of the counter C is performed. Next, proceeding to step 145, it is determined whether or not the count value of the counter C is normal,
If the determination is affirmative, the process proceeds to step 150, and if the determination is negative, the process proceeds to step 155. In step 150 executed when the count value of the counter C is normal, after performing a process of setting the count value of the counter C to the steering angle δH,
Proceed to step 160. On the other hand, in step 155 executed when the count value of the counter C is not normal, the steering angle δH
After performing the process of setting the data ERR indicating the abnormality in (1), the process proceeds to step 160. In step 160, a process of outputting the value of the steering angle δH to the ECU 8 is performed. Next step 165
Then, in preparation for the next process, the steering angle sensor first detection signal SS1 (n) in the current process is replaced by the steering angle sensor first detection signal SS1 (n-1) in the previous process, and the steering angle in the current process. After setting the sensor second detection signal SS2 (n) to the steering angle sensor second detection signal SS2 (n-1) in the previous processing, the process returns to step 110 again. Thereafter, the present steering angle detecting process is repeatedly executed by repeating steps 110 to 165.

Next, the steering angle correction processing executed by the ECU 8 will be described with reference to the flowchart of FIG. This steering angle correction process is executed when the ECU 8 is started. First step 200
Then, initialization processing such as resetting a correction counter CH for counting a correction condition satisfaction time described later to a value of 0 is performed.
Next, the routine proceeds to step 203, where a process of resetting the correction completion flag FH, which indicates whether or not the steering neutral position signal output process after the correction condition described later is satisfied, to 0, is performed. In the following step 205, since the steering neutral position signal output processing after the correction condition is satisfied has not been completed normally, processing for outputting the steering neutral position signal SC (value 1) to the steering signal processing device 3 is performed. Next, the routine proceeds to step 210, where a process of reading the wheel speed signals of the respective wheels detected by the wheel speed sensors 4, 5, 6, 7 is performed. In the following step 215, the wheel speed Vωi (i = FL, FR, RL, RR) and the wheel acceleration ω of each wheel are obtained from each wheel speed signal read in step 210.
Processing for calculating i (i = FL, FR, RL, RR) is performed. Next, the routine proceeds to step 220, where a process of reading the steering angle δH transmitted from the steering signal processing device 3 is performed. In the subsequent step 225, it is determined whether or not the value of the steering angle δH read in step 220 is data ERR indicating abnormality, or whether or not the correction completion flag FH has been reset to 0.
If an affirmative determination is made, the value of the steering angle δH is abnormal, or the steering neutral position signal output processing after the correction condition is satisfied has not been completed normally. A process for outputting the steering neutral position signal SC (value 1) is performed, and further, the process proceeds to step 233 to reset the correction completion flag FH to a value 0, and then returns to step 210, while a negative determination is made. And step 235
Proceed to. In step 235 executed when the steering angle δH is normal, it is determined whether or not the correction condition is satisfied. When the determination is affirmative, the process proceeds to step 245, and when the determination is negative, the process proceeds to step 240. . Here, the correction condition is
That is, the vehicle is in a straight running state, and the following equations (1) to (6) are satisfied. That is, since it is easy to make an erroneous determination during low-speed running, as shown in the following equation (1),
4-wheel wheel speed Vωi that all of the reference speed Vomega _TH1 or more.

_{Vωi ≧ Vω TH1 ... (1)} 4 -wheel wheel speed ωi is, not more than all the reference speed omega _TH, that the vehicle is not in acceleration or deceleration state.

ωi ≦ ω _TH (2) The speed difference between the left and right front wheels is equal to or lower than the front wheel reference speed Vω _TH2 , and the vehicle is not in a turning traveling state.

| Vω _FR −Vω _FL | ≦ Vω _TH2 ... (3) The speed difference between the left and right rear wheels is less than or equal to the rear wheel reference speed difference Vω _TH3 , and the vehicle is not turning.

| Vω _RR −Vω _RL | ≦ Vω _TH3 (4) The speed difference between the front and rear diagonal wheels is the two reference speed differences Vω _TH4 and V
ω _TH5 or less, and that the straight running state is not misjudged due to the tire diameter difference between the left and right wheels.

| Vω _FR −Vω _RL | ≦ Vω _TH4 … (5) | Vω _FL −Vω _RR | ≦ Vω _TH5 (6) When any one of these equations (1) to (6) is not satisfied, that is, In step 240 executed when the correction condition is not satisfied, the count value of the correction counter CH is set to the value 0.
Then, the process returns to step 210.
On the other hand, when all of the equations (1) to (6) are satisfied, that is, when the correction condition is satisfied, step 24 is executed.
At 5, a process of adding the value 1 to the count value of the correction counter CH is performed. In the following step 250, the steering angle maximum value δHMAX and the steering angle minimum value δMIN are read from the steering angle δH read in step 220 and stored during the time when the correction condition is satisfied.
Is calculated. Then go to step 255,
It is determined whether or not the count value of the correction counter CH has exceeded a reference count value N corresponding to the reference duration time. If a negative determination is made, it is determined that the correction condition fulfillment state has not continued for the reference duration time or more, and step 210 On the other hand, if an affirmative determination is made, the process proceeds to step 260 assuming that the correction condition fulfillment state has continued for the reference continuation time or longer. Step 26 executed when the correction condition fulfillment state continues for the reference continuation time or longer
At 0, it is determined whether or not the difference between the maximum steering angle value δHMAX calculated at step 250 and the minimum steering angle value δHMIN is smaller than or equal to the small angle ε, and if the determination is negative, the steering angle is not at the steering neutral position. As a return to step 210 via step 240,
On the other hand, if a positive determination is made, the process proceeds to step 265. Step 2
In 65, a process of transmitting the steering neutral position signal SC (value 1) to the steering signal processing device 3 is performed assuming that the steering angle is at the steering neutral position. In the following step 270, a process of setting a correction completion flag FH, which indicates that the steering neutral position signal output process after the correction condition is satisfied normally, to a value of 1, is performed, and then the process returns to step 210. After that, the steering angle correction process
Steps 210 to 270 are repeatedly executed.

In this embodiment, the steering angle sensor 2 corresponds to the steering state detecting means M1, and the steering signal processing device 3 and the processing executed by the steering signal processing device 3 (steps 125 to 16)
5) functions as the steering angle calculation means M2. Further, the wheel speed sensors 4, 5, 6, 7 correspond to the traveling state detecting means M3, and the ECU 8
And the processing executed by the ECU 8 (steps 210, 215, 235) is performed by the straight traveling state determination means M4 (steps 220, 245-2).
65) function as the steering neutral position identification means M5.

As described above, according to the present embodiment, the steering angle δH determined from the steering angle sensor first detection signal SS1 and the steering angle sensor second detection signal SS2 output from the steering angle sensor 2 is output to the wheel speed sensors 4, 5, and The change of the steering angle δH during the continuation time of the correction condition in which it is determined that the vehicle is in the straight running state based on the wheel speed Vωi and the wheel acceleration ωi obtained from the wheel speed signals detected by the wheel speed detection signals 6, 7 In the following cases, it is assumed that the steering is in the neutral position and the counter C for determining the steering angle δH is used.
Is reset to the value 0, so that regardless of the running state of the vehicle,
The erroneous determination of the steering neutral position can be prevented, and the steering neutral position can always be accurately determined.

In addition, since the steering angle sensor 2 does not need to have the origin signal generating function corresponding to the steering neutral position and the steering signal processing device 3 does not need to have the steering neutral position determining function, the highly reliable steering neutral position can be realized with a simple device configuration. It can demonstrate detection performance.

Furthermore, since the steering angle sensor 2 does not require the origin signal generating function, a very high accuracy is not required when the steering angle sensor 2 is mechanically mounted.

In the present embodiment, in the steering angle correction process, it was determined whether or not the correction condition that the vehicle is in the straight running state is satisfied based on the wheel speed signals detected by the wheel speed sensors 4, 5, 6, 7. . However, for example, when the lateral acceleration or the yaw rate of the vehicle detected by the lateral acceleration sensor 13, the yaw rate sensor 14, or the like is equal to or less than a predetermined reference value set, the vehicle is assumed to be in a straight running state, and the correction conditions The same effect can be obtained even if it is configured to determine that

[Effects of the Invention] As described above in detail, the vehicle steering angle detection device of the present invention is obtained from the detected steering state during the period in which it is determined that the vehicle is in the straight traveling state based on the traveling state of the vehicle. When the change in the steering angle is equal to or less than a predetermined value continuously for a predetermined time or more, it is configured that the steering angle of the vehicle is identified as being in a steering neutral position. For this reason, the steering angle determined from the detected steering state is corrected according to the change in the steering angle while the straight traveling state is continuing, so that an excellent effect that the steering angle can be accurately identified as being in the steering neutral position can be obtained. Play.

Further, since it is not necessary to provide the steering state detecting means or the steering angle calculating means with a function for generating or determining the steering neutral position identification signal, the device configuration is simplified and the reliability is improved.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram conceptually illustrating the present invention, and FIG.
FIG. 3 is a system configuration diagram of one embodiment of the present invention, FIG. 3 is a perspective view of the steering angle sensor, FIG. 4 is a timing chart of the steering angle sensor detection signal, and FIG. FIG. 6 is a graph showing the control map, and FIG. 7 is a flowchart showing the control. M1 ... steering state detection means, M2 ... steering angle calculation means, M3 ...
… Running state detecting means, M4… straight running state determining means, M5
... Steering neutral position discriminating means 1... Brake control device 2... Steering angle sensor 3... Steering signal processing device 4, 5, 6, 7. ), 3a, 8a …… CPU

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ identification code FI B62D 137: 00 (58) Investigated field (Int.Cl. ⁶ , DB name) B62D 6/00 B60G 17/00 G01B 21/22

Claims (4)

(57) [Claims] 1. A steering state detecting means for detecting a steering state of a vehicle, a steering angle calculating means for calculating a steering angle of the vehicle based on a detection result of the steering state detecting means, and detecting a running state of the vehicle. Running state detecting means, a straight running state determining means for determining whether or not the vehicle is in a straight running state based on a detection result of the running state detecting means, If the change in the steering angle calculated by the steering angle calculation means is equal to or less than a predetermined value during a period in which it is determined that the vehicle is running straight, the steering angle is at the steering neutral position. And a steering neutral position identifying means for identifying the vehicle steering angle. 2. The vehicle according to claim 1, wherein said traveling state detecting means includes lateral movement state detecting means for detecting a lateral movement state of said vehicle, and judges a traveling state of said vehicle based on said lateral movement state. 2. The vehicle steering angle detecting device according to claim 1. 3. The vehicle steering angle detecting device according to claim 2, wherein said lateral motion state detecting means is constituted by a lateral acceleration sensor for detecting an acceleration applied in a lateral direction of the vehicle. 4. The vehicle steering angle detecting device according to claim 2, wherein said lateral motion state detecting means is constituted by a yaw rate sensor for detecting a yaw rate.