JPH0643188B2 - Steering sensor zero point correction method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for correcting the zero point position of a steering sensor that detects a steering angle of a vehicle.

(Prior Art and Problems Thereof) Since a steering angle of a vehicle is detected and required electronic control such as power steering is performed, a steering sensor may be conventionally provided in the vehicle. This steering sensor is first installed in the vehicle by aligning its zero point with the neutral position of the steering wheel (steering angle = 0 °), but it may contain some errors due to variations in adjustment, and In some cases, the position of the zero point adjusted at the time of assembling is slightly deviated with the passage of time, and an error occurs in the detection output subsequently. In such a case, if readjustment is performed, an accurate detection output can be obtained again, but it is necessary to regularly check whether the 0-point position is displaced, and when the 0-point position is displaced, This is very troublesome because the readjustment work must be performed manually.

(Object of the Invention) An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a steering sensor zero point correction method capable of automatically correcting the steering sensor zero point position.

(Means for Achieving the Object) In order to achieve the above object, in the steering sensor zero-point correction method according to the present invention, the steering data output from the steering sensor is sampled while the vehicle is traveling, and the distribution of the sampling data is calculated. By obtaining a representative value, a 0-point correction value of the steering sensor is obtained, and the steering data is corrected by the correction value.

(Embodiment) FIG. 1 is a block diagram showing an embodiment of a 0-point correction method for a steering sensor according to the present invention. The output signal of the steering sensor 1 for detecting the steering angle (voltage value signal corresponding to the steering angle) is A /
An analog signal is converted into a digital signal by the D converter 2 and is taken into the central control unit (CPU) 3.
On the other hand, the output signal of the vehicle speed sensor 4 for detecting the vehicle speed (pulse signal having a repetition frequency corresponding to the vehicle speed) is F / V.
The converter 5 performs frequency-voltage conversion, the A / D converter 2 further converts an analog signal into a digital signal, and the converted signal is taken into the CPU 3. CPU 6 has memory 6
Also, a display 7 is connected, and the CPU 3 uses the memory 6 to perform arithmetic processing for 0-point correction as described in detail below based on the above-mentioned captured signal.
Then, the processing result is displayed on the display 7 and is output to a required place.

FIG. 2 is a flowchart showing in detail an example of the processing procedure of the 0-point correction processing in the CPU 3 of FIG. When the process is started, initialization such as clearing of the memory contents is first performed in step S1, and subsequently, x and v at the present time are input in step S2. Here, x is steering data from the steering sensor 1, and v is the vehicle speed sensor 4.
It is the vehicle speed data from.

Next, in step S3, the input steering data x at the present time is corrected by the zero point correction value c (described later) at the present time, and x-c is output as the corrected steering data. Subsequently, in step S4, it is determined whether or not v ≠ 0, that is, whether or not the current vehicle speed is 0 (in other words, whether or not the vehicle is traveling), and further in step S5, the preset sampling time T
It is determined whether _s has elapsed. When the determinations in steps S4 and S5 are both "Yes",
That is, the process proceeds to the next step S6 only when the vehicle is traveling and the sampling time T _s has elapsed, and otherwise returns to step S2 to repeat the above-described process again.

In step S6, it is determined whether or not m> n. Here, m means the number of times of sampling at the present time (that is, equivalent to the number of data sampled up to the present time), and n means the number of sampling data set in advance (for example, n = 2).
56 may be set). Since m <n within the fixed time after the processing is started, the determination in step S6 is “No”, and at this time, the processing is performed in step S
Proceed to 7. In step S7, the steering data x and the vehicle speed data v input in step S2 are stored in the memory 6 as sampling data in association with each other. Then, the process returns to step S2 again to repeat the above-described process, and the sampling data is accumulated in the memory 6.

When the number of times of sampling m exceeds the set value n after a while, the determination in step S6 becomes "Yes", and the process proceeds from step S6 to step S8. Step S
In 8, the sampling data when the vehicle speed is the lowest (that is, the vehicle speed data v is the lowest) among the sampling data accumulated in the memory 6 is erased. Then, in step S9, instead of the erased sampling data, the current (that is, input in the immediately preceding step S2)
The steering data x and the vehicle speed data v are stored in the memory 6 in association with each other as sampling data.

By the way, generally, the frequency of the steering angle of the running vehicle has a normal distribution or a distribution close to a normal distribution as shown by the solid line in FIG. In Fig. 3, the vertical axis represents frequency,
The horizontal axis represents the steering angle (°), and the center is the neutral position of the steering wheel (steering angle =
0 °). Assuming that there is no error in the steering sensor 1, the actual steering angle and the detected angle of the steering sensor 1 match, so the set of steering data x obtained by sampling the output of the steering sensor 1 is actually Similarly to the steering angle, the normal distribution is obtained as shown by the solid line in FIG. However, when there is an error in the steering sensor 1, the actual steering angle and the detected angle of the steering sensor 1 are always deviated by an error. Therefore, the set of steering data x obtained by sampling the output of the steering sensor 1 is As shown by the dotted line in FIG. 3, the central portion of the distribution is shifted by an error amount to form a normal distribution. That is, the error of the steering sensor 1 can be known by obtaining the central portion of the distribution (in other words, the representative value of the set).

The representative value of the set includes the average value, median value, mode value, etc. (These values are all the same in the normal distribution)
However, in this embodiment, the central portion of the distribution is obtained by the average value. In step S10, the average value of the set of steering data x stored in the memory 6 as described above is calculated for this purpose. Then, in the following step S11, this is registered as the 0-point correction value c. Then, the process returns to step S2, and after inputting the current steering data x and vehicle speed data v, step S2 is executed.
3, the steering data x just input is corrected by the 0-point correction value c registered in step S11,
Obtain steering data without error.

In the above embodiment, after the sampling data stored in the memory 6 reaches the predetermined number n, the sampling data having the lowest vehicle speed is sequentially erased in step S8. Sampling data will remain. In general, the steering angle is small during high-speed running, and therefore, the data remaining in the memory 6 becomes closer to the center of the normal distribution as time passes. The state of the distribution at this time is shown in FIG. In this way, as the time elapses, the variation between the steering data, which is the basis of error detection, becomes smaller, so that the error can be detected more accurately.

(Effects of the Invention) As described above, according to the present invention, it is possible to realize a steering sensor zero point correction method capable of automatically correcting the steering sensor zero point position.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a flow chart showing a processing procedure according to the present invention, and FIGS. 3 and 4 are diagrams showing data distribution. 1 ... Steering sensor 3 ... CPU 4 ... Vehicle speed sensor

Claims (3)

[Claims] 1. A method for correcting a zero point position of a steering sensor for detecting a steering angle of a vehicle, wherein steering data output from the steering sensor is sampled while the vehicle is traveling, and a distribution of the sampling data is sampled. Is obtained to obtain a 0-point correction value of the steering sensor, and the steering data is corrected by the correction value. 2. The method for correcting a zero point of a steering sensor according to claim 1, wherein the value representative of the distribution of sampling data is an average value. 3. The zero-point correction method for a steering sensor according to claim 2, wherein the steering data used in the averaging is a predetermined number in order from the vehicle speed at the time of sampling.