JP3341345B2 - Steering neutral arithmetic unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arithmetic unit for obtaining steering neutrality.

[0002]

2. Description of the Related Art Conventionally, there has been known a method of obtaining steering neutrality from an average value of steering angles sampled at every fixed traveling distance.

[0003]

Here, if the number of samplings of the steering angle increases, the average value can be regarded as being equal to the neutral steering angle in the straight traveling state of the vehicle. However, when the sampling number of the steering angle is small, the influence of the abnormal value is large, and there is a concern that the average value deviates from the steering neutral steering angle in the straight traveling state of the vehicle. Therefore, the steering neutral is determined, and the control based on the left and right steering angles from the steering neutral (for example,
There is a problem that a predetermined sampling number is required to enter the steering angle-sensitive power steering control), and the control start timing is delayed by that amount.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to provide an accurate steering-neutral calculating device that requires less time to determine steering neutrality. It is to be.

[0005]

A first feature of the invention for solving the above-mentioned problems is that a relative rotation angle and a rotation direction of a steering shaft accompanying rotation of a steering wheel of a vehicle are detected. A steering neutral calculating device having a steering sensor and calculating steering neutral based on a signal from the sensor, a steering angle calculating means for calculating a steering angle of the steering shaft based on a transition state of a signal detected by the sensor If, medium steering angle steering angle calculated the most frequently often to emerge at a predetermined sampling interval by該舵angle calculating means
Intermediate and neutral calculating means for calculating as a stand, a sampling number calculated neutral by the neutral operation means, and the average of the steering angle and the steering angle of the average or the most frequent steering angle in accordance with the running distance or time elapsed And neutral transition means for transitioning to.

[0006]

According to the above means, the steering angle of the steering shaft is calculated based on the transition state of the signal of the steering sensor. The steering angle at which the steering angle appears most frequently at a predetermined sampling interval is calculated as neutral . Neutral obtained by this frequency is shifted to neutral obtained by averaging according to the number of samples, traveling distance or elapsed time up to that point, or intermediate between the above frequency and the above average. In this way, the steering neutrality is quickly determined based on the frequency at the beginning of traveling, and the predetermined sampling number,
After the mileage or elapsed time, it is shifted to the average or the middle between them to make it more accurate.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to specific embodiments. FIG. 1 shows a mechanical configuration of a steering sensor constituting a steering neutral operation device according to the present invention, and FIG. 2 is an explanatory diagram showing an output signal from the sensor.
FIG. 3 is a block diagram showing an electrical configuration of the apparatus of the embodiment. Vehicle steering wheel 10
A slit disk 25 is concentrically fixed to a rotating shaft 13 that connects the steering shaft 11 on which is fixed to an input shaft 15 on the side of a power steering device (not shown). Two sets of photo-interrupters 21 having a U-shape are provided on the fixed side member so as to sandwich the slit disk 25, and the steering sensor 20 is configured. A large number of the same-shaped slit portions 25a are formed at equal angular intervals over the entire circumferential range of the slit disk 25.

When the steering wheel 10 is steered, the steering sensor 20 outputs two output signals as shown in FIG. Detector 2 composed of slit 25a and two sets of photo interrupters
1 and two types of on / off signals (S
S1 signal and SS2 signal) are output. Since the output states of the SS1 signal and the SS2 signal differ depending on the left-right rotation direction, the rotation angle and the rotation direction of the steering shaft 11 are detected. That is, when the SS2 signal is at the H (High) level at the rising time of the SS1 signal, the clockwise rotation is performed. When the SS2 signal is at the L (Low) level at the rising time of the SS1 signal, the clockwise rotation is performed. It can be understood that the angle is a predetermined angle up to the rise. The change from the rising of the SS1 signal to the next rising (corresponding to the unit angle at which the steering shaft 11 is rotated) is incremented or decremented as a counter C value in a counter C area 331 of a RAM 33 in the ECU 30 described later. It is memorized.

FIG. 3 is a block diagram showing an electric configuration of the SS1 signal and the SS2 signal output from the steering sensor 20 and an ECU (Electronic Control Unit) 30 to which those signals are input. is there. The ECU 30 includes a CPU 31, a ROM 32 storing a control program, and a RAM 33 storing various data.
And an interface 34. The RAM 33 has a counter C area 331 for storing a counter C value for calculating the current angle of the steering shaft 11 and a frequency counter area 332 for storing each frequency incremented each time the counter C value appears. Have been.

Next, a description will be given of a processing procedure of the CPU 31 used in the apparatus of this embodiment with reference to a flowchart for achieving the steering angle calculating means of FIG. This program is for obtaining an angle associated with the rotation of the steering shaft 11 and its rotation direction, and is an interruption process by the rising of the SS1 signal. When the SS1 signal rises, the process proceeds to step 102 after reading the SS2 signal in step 100. Step 102
Then, it is determined whether the SS2 signal read in step 100 is at the H level. When the SS2 signal is at the H level, the process proceeds to step 104, and as described above, the steering shaft 11 is clockwise, the counter C indicating the rotation angle of the steering shaft 11 is incremented by (C + 1), and the program ends. . The counter C has been initialized (C = 0) in advance by a program shown in FIG. Here, the above step 10
In step 2, when the SS2 signal is at the L level, the process proceeds to step 106, where the steering shaft 11 is rotated leftward as described above, and the counter C is decremented to (C-1).

Next, a description will be given of a processing procedure of the CPU 31 used in the apparatus according to the embodiment with reference to a flowchart for achieving the neutral operation means in FIG. This program is repeatedly executed every predetermined traveling distance of the vehicle from the time when the ignition switch is turned on. First, in step 200, a counter C representing the current angle of the steering shaft 11 is set to 0 as initialization. The counter C is an integer counter, and a change in the value from 0 to 1 indicates that an angle change of one pitch of the SS1 signal has occurred with the right rotation of the steering shaft 11.
Next, the process proceeds to step 202, where the value of the counter C at that time is read, and the process proceeds to step 204. Step 2
In 04, the frequency counter corresponding to the C value read in step 202 is incremented. Next, the routine proceeds to step 206, where the first highest frequency counter is calculated. Next, the process proceeds to step 208, where the frequency 2
The next highest frequency counter is calculated. Then step 2
Moving to 10, the difference between the first and second frequencies is calculated. Then, in step 212, the above-described step 210 is performed.
When the difference calculated in step S2 becomes equal to or _larger than the threshold value HC for determining the steering neutrality, the process proceeds to step 214. In step 214, the value obtained by subtracting the C value corresponding to the frequency counter having the highest frequency from the value of the counter C is set as the current value of the counter C, and then the present program is terminated. still,
If it is determined in step 212 that the difference is less than the threshold value H _C , the processing in steps 202 to 212 described above is repeated at a predetermined timing.

According to the above processing, when the steering is actually at the neutral point, the value of the counter C becomes 0 (determination of the steering neutrality by the frequency). That is, the origin calibration of the counter C based on the frequency is performed. This allows
The control is shifted from neutral steering to control based on the value of the counter C (a value proportional to the left and right steering angles) (for example, steering angle sensitive power steering control). In the early stage of the running, the control based on the above-described frequency is performed, so that the influence of the abnormal value is unlikely to appear, so that the number of samplings is small and the time for determining the steering neutrality is reduced.

Further, the CPU 31 executes processing based on a flowchart for achieving the neutral shift means in FIG.
Note that this program is repeatedly executed for each predetermined traveling distance after the end of the program of FIG. Step 300
Then, it is determined whether or not steering neutrality based on frequency has already been determined. If determined, the process proceeds to step 302, and if not determined, the processing of this program is terminated. In step 302, an average steering neutrality is calculated based on the counter C (steering angle) and the frequency (frequency) of the frequency counter. Next, proceed to step 304,
The deviation between the steering neutrality based on the frequency (the value of the counter C is 0) and the average steering neutrality calculated in step 302 is calculated. Next, the routine proceeds to step 306, where the steering neutral transition ratio based on the traveling distance is calculated from the map shown in FIG. The map in FIG. 7 shows the ratio of the shift from the steering neutrality based on frequency to the steering neutrality based on the average, and indicates that as the traveled distance increases, the steering shifts toward the neutral steering based on the average. Next, the routine proceeds to step 308, where the deviation calculated in step 304 and the transition ratio calculated in step 306 are multiplied to calculate a steering neutral transition value. It should be noted that this transition value is set to an integer by rounding, for example, that is, it matches the minimum resolution of the steering angle. Then, the process proceeds to step 310, and after the value obtained by subtracting the value of the counter C by the transition value calculated in step 308 is set as the current value of the counter C, the program ends. By the above processing, when the steering is actually at the neutral point, the value of the counter C becomes 0 (determination of the steering neutrality between the frequency and the average). That is, the origin calibration of the counter C based on the frequency and the average is performed.

As described above, as the traveling distance (the number of samplings) increases, as shown in FIG. 8, the processing is shifted from the steering neutrality based on the frequency to the steering neutrality based on the average or the middle thereof. By shifting to the average or the middle thereof, a more accurate steering neutrality can be recognized. Further, in the above-described steering-neutral transition process, a process of increasing the sampling interval according to the number of samples, the traveling distance, or the traveling time is performed. As a result, there is an effect that the driver does not feel uncomfortable in steering because the transition of the steering neutral state does not become too sharp.

Here, the following conditions can be assumed as the steering angle sampling conditions. During rotational steering, the vehicle speed is hard to be higher than a certain value. When the vehicle is traveling substantially straight, the steering speed of the steering wheel does not increase. Therefore, the steering angle is sampled only when the steering speed is equal to or less than a certain value. Further, it is also possible to interpolate and control between the steering angle sensitivity and other vehicle speed sensitivity according to the number of samples or the traveling distance, instead of the complete steering angle sensitivity from the beginning.

[0016]

As described above, in the apparatus of the present invention,
At the beginning of traveling, the steering neutrality is set based on the frequency, and thereafter, the steering neutrality is set to an average or an intermediate value between the frequency and the average. For this reason, the steering neutrality has an effect that a quick determination can be made at the beginning of traveling and accuracy can be obtained thereafter.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a mechanical configuration of a steering sensor included in a steering neutral operation device according to a specific embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an output signal from a steering sensor.

FIG. 3 is a block diagram showing an electrical configuration of the apparatus of the embodiment.

FIG. 4 is a flowchart showing a processing procedure of a CPU used in the apparatus of the embodiment.

FIG. 5 is a flowchart showing a processing procedure of a CPU used in the apparatus of the embodiment.

FIG. 6 is a flowchart showing a processing procedure of a CPU used in the apparatus of the embodiment.

FIG. 7 is a map showing a transition ratio of steering neutrality with respect to a traveling distance used in the apparatus of the embodiment.

FIG. 8 is an explanatory diagram showing a transition of steering neutrality according to the device of the embodiment.

[Explanation of symbols]

 10: Steering wheel 11: Steering shaft 20: Steering sensor 25: Slit disk

Continuation of the front page (56) References JP-A-61-28811 (JP, A) JP-A-62-157510 (JP, A) JP-A-2-216411 (JP, A) JP-A-4-201680 (JP) JP-A-4-252912 (JP, A) JP-A-4-369417 (JP, A) JP-A-5-85392 (JP, A) JP-A-5-147548 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B62D 5/00 B62D 6/00

Claims (1)

(57) [Claims] 1. A steering neutral operation which has a steering sensor for detecting a relative rotation angle and a rotation direction of a steering shaft accompanying rotation of a steering wheel of a vehicle, and obtains steering neutral based on a signal from the sensor. A steering angle calculating means for calculating a steering angle of the steering shaft based on a transition state of a signal detected by the sensor; and a steering angle calculated by the steering angle calculating means at a predetermined sampling interval. Neutral steering angle that is most frequently issued
A neutral calculating means for calculating as a neutral calculated by the neutral operation means sampling number, in the middle of the steering angle of the average or the most frequent steering angle in accordance with the running distance or elapsed time and the average of the steering angle And a neutral shift means for shifting.