JPH04252912A - Steering position detector for automobile - Google Patents

Abstract

PURPOSE:To obtain a steering position detector for automobiles which can stably detect a correct steering neutral position. CONSTITUTION:A steering position detector for automobiles comprises optical sensors 5,6 for detecting steering angles due to rotation of a steering wheel, a neutral range detecting unit for outputting a neutral range signal when the steering position belongs to a predetermined steering range including a steering neutral position, a speed sensor 12 for detecting travel speed of an automobile, a frequency count value creating unit which counts a number multiplied by a weighted coefficient according to speed every time the automobile has traveled by a predetermined distance while the steering angle detected when the neutral range signal is output is maintained with respect to a counter set correspondingly to the steering angle, and a neutral position calculation processing unit which calculates the steering neutral position from the maximum counted value of the counter specified for each steering angle.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering position detection device for a vehicle, and is suitable for use in a steering control device or a suspension control device.

0002

2. Description of the Related Art A conventional vehicle steering position detection device is disclosed in, for example, Japanese Patent Laid-Open No. 61-28811. In this conventional device, a rotating disk is attached to the steering shaft, and this rotating disk is provided with a hole for detecting the steering angle and a hole for detecting the neutral zone of the steering position. By arranging optical sensors corresponding to these hole positions, it is possible to detect the steering position neutral zone and the steering angle. In such a configuration, the average value of the steering angles when the steering position neutral zone is detected is calculated, and this calculated value is detected as the steering neutral position.

[0003] In the above conventional device, it is stated that a vehicle speed sensor is added to the configuration and the above calculation is performed when the vehicle speed is equal to or higher than a predetermined vehicle speed. This is because when driving at high speeds, the steering wheel is rarely rotated more than 360 degrees, and it is impossible for the steering position neutral zone to be detected when the steering position has been rotated more than 1 turn. This is to make the zone a true neutral zone.

0004

[Problems to be Solved by the Invention] Here, when a vehicle turns in a gentle arc on a highway or when a lane change is performed, a state in which the vehicle is steered continues for a relatively long period of time. In such a case, since the traveling speed of the vehicle is high, the steering angle belongs to the steering position neutral zone. Therefore, in the conventional device, the above-mentioned steering angle is taken in as data for determining the neutral steering position even though the vehicle is in the steering state, and as a result, an incorrect neutral steering position is detected.

Furthermore, even when it is necessary to operate the steering wheel in small steps, such as on a road in a mountainous area, the steering angle is not concentrated at the neutral steering position when the steering position neutral zone is detected; A similar problem arises. The present invention has been made in view of the above points, and an object of the present invention is to provide a vehicle steering position detection device that can stably detect an accurate neutral steering position.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the vehicle steering position detection device according to the present invention, as shown in FIG. a neutral range detection means for outputting a neutral range signal when a steering position belongs to a predetermined steering range including a steering neutral position; a speed detection means for detecting a traveling speed of the vehicle; weighting means for weighting the steering angle according to the vehicle speed at that time each time the vehicle travels a predetermined distance while maintaining the detected steering angle; and statistical processing of the weighted steering angle. Accordingly, a neutral position calculating means for calculating a steering neutral position is provided.

[0007]

[Operation] According to the above configuration, when a neutral range signal indicating that the steering position belongs to a predetermined steering range including the neutral steering position is output, the detected steering angle is maintained for a predetermined distance. Each time the vehicle travels, this steering angle is weighted according to the vehicle speed at that time.

[0008] Generally, when a vehicle turns, its speed decreases, and when it is running at high speed, it often travels straight. Furthermore, when driving at extremely high speeds, such as when driving on a highway, the direction of the vehicle can be changed with a slight turn of the steering wheel. Therefore, by detecting the steering angle in consideration of such vehicle speed information and calculating the neutral steering position based on the detected steering angle, it becomes possible to detect the neutral steering position more accurately.

Therefore, in the present invention, each time the vehicle travels a predetermined distance while the steering angle is maintained, the steering angle is used as data for calculating the neutral steering position. For this reason, the more data the vehicle is traveling at, the more data is output, and we are trying to utilize vehicle speed information in this respect. Furthermore, in the present invention, by weighting the steering angle in accordance with the vehicle speed at that time, it is possible to calculate the steering neutral position in consideration of vehicle speed information.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 2, a rotating disk 2 is concentrically arranged and fixed to a steering shaft or a shaft member 1 that rotates integrally with the steering shaft. This rotary disk 2 has a plurality of holes 3 (for example, 20 holes per rotation) for detecting the steering angle, and a hole 4 for detecting the neutral range of the steering position.
is formed. The detection holes 3 are formed at equal angular pitches. For example, in the case of 20 detection holes per rotation, holes with a width of 9 degrees are provided at intervals of 9 degrees. Further, the detection hole 4 has a predetermined angle range (for example, 5
4 degrees), and even if we take into account all factors that affect straight running, such as the accuracy of vehicle assembly and the unevenness of the passenger arrangement, the angle range is such that the steering neutral position always falls. It is set.

Optical sensors 5, 6 and 7 are provided for these detection holes 3 and 4, respectively. These optical sensors 5, 6, and 7 are composed of, for example, a photointerrupter, that is, a light emitting diode and a phototransistor, which are placed facing each other, and the presence or absence of a detection hole therebetween is converted into ON/OFF of an electric signal. Note that the optical sensors 5 and 6 are
It is arranged so that ON and OFF signals depending on the presence or absence of the detection hole 3 are outputted with a phase shift of 90 degrees.

Further, 12 is a vehicle speed sensor, which outputs a signal corresponding to the traveling speed of the vehicle. In this embodiment, a steering angle calculation is performed in which a steering neutral position is detected based on signals output from these optical sensors 5, 6, and 7 and the vehicle speed sensor 12, and a steering angle is calculated from a relative angle with respect to this steering neutral position. A processing section 10 is provided. This steering angle calculation processing section 10 will be explained using FIGS. 2 and 3.

In FIG. 2, the steering angle calculation processing section 10 has a steering angle detection section 8, which inputs the output signals of the optical sensors 5 and 6 and outputs the output signals from the optical sensors 5 and 6 to a neutral position detection section 9, which will be described later. The steering angle and steering direction are calculated using the steering neutral position 8 as a reference. Specifically, a steering angle detection counter is provided, and the steering angle count value S is counted each time a signal change of output signals SS1 and SS2 is detected, for example, with right steering as + and left steering as -.

The neutral position detection section 9 detects the steering neutral position based on the neutral range signal SSC of the optical sensor 7, the vehicle speed V detected by the vehicle speed sensor 12, and the steering angle count value S output from the steering angle calculation processing section 8. Detects the position and outputs a neutral signal Z. A detailed block diagram of the neutral position detection section 9 is shown in FIG. The neutral range detection unit 91 detects a neutral range signal S that appears many times because the steering wheel rotates many times.
The true neutral range signal is determined from among the SCs. Further, the neutral position calculation unit 92 detects the steering neutral position from within the neutral range. Furthermore, the neutral position correction processing section 93 is for correcting the neutral position when it changes due to a change in the number of occupants or the like.

Next, the functions of each processing section will be specifically explained. First, the steering angle detection section 8 will be explained. The output signals SS1 and SS2 of the optical sensors 5 and 6 are arranged so that ON and OFF waveforms depending on the presence or absence of the detection hole 3 are output with a phase shift of 90 degrees. Therefore, the output signals SS1 and SS are different when the shaft member 1 rotates clockwise (right steering) and when it rotates counterclockwise (left steering).
2 have different phase relationships. The situation is shown in FIGS. 4 and 5. Further, the relationship between FIGS. 4 and 5 is summarized as shown in FIG. 6. Therefore, right steering and left steering are determined according to FIG. 6 every time the output signals SS1 and SS2 change in logic, and the steering angle detection counter, which takes the steering neutral position as zero, is set to
1 count, and when steering to the left, -1 count is performed on the current count value. As a result, the count value corresponds to the steering angle. For example, if the rotary disk 2 is provided with 20 detection holes 3 per rotation, one count corresponds to 4 or 5 degrees, and the detection hole is 2.2 if there are 40 pieces.
Corresponds to the fifth degree.

Next, the neutral range determining section 9 of the neutral position detecting section 9
1 will be explained. First, the neutral range determination unit 91 determines the true neutral zone from among the neutral range signals SSC that appear many times because the steering wheel rotates many times. Therefore, consider this problem as follows. In other words, a driving condition that generates a large lateral acceleration (a condition in which the vehicle is making a sharp turn such that it is in the limit driving range) does not continue for a long time. Therefore, in a state where a vehicle speed equal to or higher than a predetermined threshold vehicle speed VZ is detected, the neutral range signal SS
When C is continuously detected for a predetermined period of time TZ, that range is considered to be the true neutral range. In fact, in consideration of special driving conditions and the like, if any one of the following three conditions is satisfied, that range is determined to be a true neutral range. Note that these determination conditions are determined by the first to third determination units 91a to 91c, respectively.

(1) First determining section 91a

[0018]

[Math 1] (2) Second determination unit 91b

[0019]

[Math 2] (3) Third determination unit 91c

[0020]

[Equation 3] Regarding a certain neutral range, FIG. 7 shows the relationship between the steering positions in the above determination within a range of an angle QZ (for example, 54 degrees) from both ends of the neutral range into and out of the neutral range.

Another method for determining the true neutral range is to measure the steering amplitude in advance when the steering wheel is steered lock-to-lock, and to make a determination based on that value. An example of this method is as follows. Now, consider the case where the lock-to-lock steering amplitude is ±600 degrees and the width of the neutral range signal is 54 degrees.
The neutral range signal appears three times for lock-to-lock steering. Therefore, it is sufficient to monitor the movement of the steering amplitude, detect three neutral range signals, and set the middle of the three neutral range signals as the neutral range.

[0022] Also, in the case of this steering angle condition, even if the maximum condition is considered for the apparent neutral range other than the true neutral range, it is impossible to steer the vehicle by more than 240 degrees on both sides of the neutral range. It is. Using this fact in reverse, when the vehicle can be steered by 240 degrees or more on both sides of a certain neutral range, that neutral range can be defined as a true neutral range. This method can be said to be the most reliable method when the steering amplitude is determined to be within ±650 degrees, but when the steering amplitude becomes large and four or more neutral range signals appear, Judgment becomes complicated. Furthermore, the magnitude of the steering amplitude generally changes with the displacement of the vehicle's suspension. Therefore, depending on the vehicle model, even if the vehicle is the same, there is a possibility that the steering amplitude will be such that four or more neutral range signals appear, or the steering amplitude will be less than three, so this concept should be applied to all vehicle models. It is difficult to do so.

Next, the neutral position calculating section 92 will be explained. The neutral position calculating section 92 determines the steering neutral position from the frequency distribution of steering positions within the neutral range determined by the neutral position determining section 91. Here, it is assumed that the vehicle basically travels in a straight line, and the neutral position is considered to be the position where the steering position is most frequent. First, we will explain how to obtain the distribution of steering position frequencies.

When the steering angle count value S output from the aforementioned steering angle detection section 8 is within the neutral range obtained by the neutral range determination section 91, the frequency count value creation section 92
b is a constant distance (
For example, every time the vehicle travels (4 m), the frequency distribution counter of the steering position corresponding to the steering angle count value S is counted while weighting the vehicle speed. This frequency distribution counter is set for each angular range that divides a predetermined range centered on the neutral range. Weighting based on vehicle speed is stored in advance in the storage unit 92a, and an example thereof is shown in FIG. That is, the weighting coefficient is set to be larger as the vehicle speed is higher, taking advantage of the fact that the higher the vehicle speed is, the more the vehicle is traveling straight or a state close to it. However, if the weighting coefficient is simply set to increase as the speed increases, an incorrect steering neutral position may be determined for the reasons described below, so conversely, the weighting is reduced in the high speed range.

In other words, in a high speed range, the steering angle itself is inherently small, and the steering speed itself is slow. Therefore, if the weighting is increased, the steering position may be kept within the neutral range even though the vehicle is being steered for turning. For this reason, the frequency count to that steering position increases significantly, and the neutral position is incorrectly determined in the determination process described later. This is the reason for reducing the weighting in the high speed range. In addition, Figure 8
The vehicle speed range shown in is just an example, and can be determined according to the characteristics of the target vehicle (for example, mainly high-speed driving or mainly medium-low speed driving). However, for the reasons mentioned above, it is necessary to maintain the concept of increasing the weighting in stages as the vehicle speed increases, and reducing the weighting again when the maximum speed is reached.

As described above, the frequency for each steering position is counted, and the total sum of the count values is a predetermined value (
For example, when the frequency count reaches 256 or more), the frequency count is stopped and the analysis of the frequency distribution is started. According to the count described above, the frequency distribution has a shape similar to a normal distribution centered around the neutral position, except in special cases where slalom-like running is performed. Therefore, the normal distribution determining unit 92c determines whether or not the frequency distribution is in the shape of a normal distribution, and only when the frequency distribution is in the shape of a normal distribution, the neutral position determining unit 92d responds to the peak of the normal portion. Outputs the steering position as the neutral position.

Here, the determination of whether or not the distribution is normal by the normal distribution determining section 92c can be performed as follows. That is, basically, if the steering position having the maximum value in the frequency distribution and the steering position having the second largest value are adjacent to each other, it is determined that the distribution is normal. However, even if the two are far apart, if the difference between the count values of the two is greater than or equal to the determination threshold value Cth (for example, 10), it is determined that the distribution is normal (see Figure 9(a)). If it is less than the threshold Cth, it is determined that the distribution is not normal. In addition, if there are two steering positions with the maximum value and they are adjacent to each other, it is determined that the distribution is normal, with the steering position closest to the counter with the larger count value among the frequency counters on both sides being the neutral position. (See FIG. 9(b)). Furthermore, if there are three steering positions with the maximum value and they are consecutive, it is determined that the distribution is normal (see Fig. 9(c)),
If there is even one difference, it is determined that the distribution is not normal.

[0028] If it is determined that the distribution is normal in this manner, a neutral position is determined, and if not, the count result is discarded. Thereafter, the count values of all frequency counters are initialized to zero for the next frequency distribution counting process. Here, it is determined whether the distribution is normal or not, but in order to simplify the procedure, the maximum value may be simply determined to be the neutral position, regardless of the distribution shape.

The steering neutral position obtained by the above procedure reflects the steering condition for several tens of seconds to several minutes, and therefore a fairly reliable value can be obtained. However, under special driving conditions such as on mountainous passages, an incorrect position may be determined to be the neutral steering position. Therefore, a neutral position correction processing section 93 is provided to reduce the influence of such noise-like erroneous determination data.

The neutral position calculating section 92 described above repeatedly executes the procedure of determining the neutral position every time the frequency count corresponding to the steering position is completed, initializing the frequency counter, and executing the frequency count again. , the determination result of the steering neutral position is repeatedly output. Therefore, the neutral position correction processing section 93 performs filtering processing to remove noise components in each of the above-mentioned determination results to obtain a more stable and reliable neutral position.

Therefore, the correction counter calculation unit 93b compares the current steering neutral position Z(h-1) and the current neutral judgment position C(n), and when the two values are the same (Z(
h-1)=C(n)), 1 is added to the count value of the correction counter. However, the maximum count value of the correction counter is limited to a predetermined value m (for example, 5). On the other hand, when the two values are different (Z(h-1)≠C(n)), the deviation (ER=|Z(n-1)-C(n)|) is subtracted from the count value of the correction counter. . At this time, it is better to limit the value of the deviation ER to about 2 to 3. Further, it is necessary to distinguish between the magnitude relationship between the current steering neutral position Z(n-1) and the neutral judgment position C(n), that is, the left and right sides of the deviation of the neutral position between the current value and the judgment value. Therefore, if the correction counter is already negative before the deviation ER is subtracted, and the judgment value has shifted to the right, for example, and the deviation ER is subtracted and the judgment value becomes negative, then this time the judgment value is to the right. If it is off, you can simply subtract it. However, if it is shifted to the left this time, the count value is obtained by calculating -|count value+ER|. Note that the current neutral steering position Z(n-1) is stored in the storage section 93a, and is updated every time a new neutral steering position is output from a neutral position correction section, which will be described later.

While repeating the above procedure, when the count value reaches a predetermined value -m, it is determined that the current steering neutral position Z(n-1) has deviated from the true neutral position,
The current neutral judgment position C(n) is the steering neutral position candidate Z'(
Request correction as n). Using such a method,
When the previous steering neutral position Z(n-1) is found to be incorrect, the neutral position correction unit 93c changes the previous steering neutral position Z(n-1) in the direction of the steering neutral position candidate Z'(n). The steering wheel is moved to a new neutral steering position Z(n). Next, this correction procedure will be explained.

The steering neutral position Z(n) is a value that has extremely important meaning for suspension control and steering control that use this value. For this reason, even if it is found that it has deviated from the true neutral position,
Corrections cannot be made carelessly. This is because changing the neutral position may suddenly change the control amount or control direction, which may cause a great discomfort to the driver or cause unstable vehicle behavior. be. The easiest way to solve this problem is to make corrections while the vehicle is stopped or running at very low speeds, which does not directly affect the control system. However, this method has a problem in that it is not possible to make appropriate corrections under driving conditions where there are few opportunities for conditions where correction is possible, such as when driving on a highway.

Therefore, the neutral position correction section 93c performs correction according to the following procedure. For example, the current steering neutral position Z(n
-1) is shifted to the right with respect to the neutral position candidate Z'(n). In this case, the steering angle count value S
The movement of the vehicle is monitored, and when the vehicle is steered to the left, one count of the left steering is not subtracted from the count value S and ignored. Instead, shift the current neutral steering position Z(n-1) to the left by one count to create a new neutral steering position Z(n).
shall be. Also, if Z(n-1) is shifted to the left,
Similar processing is performed at the timing of right steering. In this way, the neutral position can be corrected without giving the driver a sense of discomfort and without causing unstable behavior of the vehicle due to careless movement of the control system. Further, in addition to the above-mentioned filtering process, a stable and reliable neutral position can also be obtained by removing noise components by the following method. That is, the n-th judgment position within the neutral range is expressed as C(n) with the steering angle position corresponding to the left end of the neutral range as a reference.

[0035]

The steering neutral position candidate Z'(n) is calculated using the following equation. Also

[0036]

The steering neutral position candidate Z'(n) may be calculated using the following equation. Here, k is a numerical value predetermined by the vehicle, for example, a value such as 4 or 8. In this way, a stable steering neutral position candidate Z'(n) can be obtained by taking the average with past determination values.

The functions described above can be realized by combining logic circuits, but they can be realized relatively easily by processing using a microcomputer. Next, the flowchart in FIG. 10 shows the processing procedure when a microcomputer is used. The process shown in the flowchart of FIG.
c) is executed repeatedly. First, in step 100, a process of counting the steering angle value S is executed. Here, similarly to the steering angle detection section 8, the output signals SS of the optical sensors 5 and 6 are
1. Each time a logical change in SS2 is detected, the steering angle detection counter is set to ±1. The logic change is obtained by comparing the logic states of the output signals SS1 and SS2 between the previous calculation cycle and the current calculation cycle, respectively.

[0038] Generally speaking, the process of monitoring the logic changes of the output signals SS1 and SS2 is repeated at a faster cycle (for example, every 0.5 m) than the calculation process of the neutral position described below.
sec) is more desirable in terms of preventing failure to detect logical changes. Therefore, the counting process in step 100 may be separated and executed at a faster cycle.

Next, the process proceeds to step 110, where it is determined whether or not a true neutral range has already been detected in the iterative process up to this point. If the neutral range has already been detected, the process moves to the steering position counting process from step 140 onwards. On the other hand, if the neutral range has not yet been obtained,
Proceeding to step 120, the neutral range determination section 91 similarly determines the neutral range.

Note that this judgment requires the measurement of a predetermined time TZ, but this is done by taking advantage of the fact that this routine is executed at equal time intervals, so long as the judgment conditions such as vehicle speed are continuous. During the process, time can be measured by continuing to add +1 to a predetermined counter and determining that the count value has reached a predetermined value. Furthermore, in step 130, it is determined whether a neutral range has been detected in the current process of step 120. If it is not detected, this process is terminated, and the determination process in step 120 is repeated from next time onwards until the neutral range is obtained.

Next, if the neutral range is detected, the process moves to the steering neutral position calculation process starting from step 140. In this process, as in the neutral position calculating section 92, first, in step 140, a frequency count is performed to obtain a steering position frequency distribution. This means that when it is determined that the steering angle is within the neutral range, a predetermined count value is added to the frequency counter set for each steering position after driving a certain distance while keeping the steering at that steering position. It is processing.

[0042] Here, a means for determining whether a certain distance has been traveled is required, and this is done by utilizing the fact that the vehicle speed value for each calculation cycle represents the distance traveled during one calculation cycle. It is possible to determine whether the vehicle has traveled a certain distance by adding the distance traveled during the period in which the steering wheel is held at the same steering angle, and whether or not the result reaches a predetermined value. In step 150, in the frequency counting performed in step 140, it is determined whether or not the sum of the count values of all counters has reached a predetermined value. If it is determined that the processing has not been completed, the main processing for the current cycle is completed, and continues until the frequency count is completed from the next time onwards. On the other hand, if the frequency count has been completed, the process proceeds to step 160 to find the steering position at which the frequency is maximum, that is, the neutral position. Then, proceed to step 170 to initialize the frequency counter,
Prepare for next neutral position determination.

Further, the process proceeds to step 180, in which a steering neutral position correction process is executed in the same manner as in the neutral position correction processing section 93 described above. Note that in this correction process, the process of performing a correction operation on the steering angle count value S is not actually performed in this step 180, but is limited to setting a flag requesting correction to the count value S, and is performed in step 180. It is best to perform correction when counting by 100. This is because the signal processing of SS1 and SS2 only needs to be performed once every calculation cycle. This is particularly suitable under conditions where if the process of step 100 is not repeated at a rapid cycle, a logical change will be missed.

After the processing has proceeded up to this point, the steering angle calculation processing is ended. Then, when the next calculation timing comes, the execution from step 100 is repeated again.

[0045]

[Effects of the Invention] As explained above, according to the present invention, the steering angle is detected in consideration of vehicle speed information, and the steering neutral position is calculated based on the detected steering angle. It becomes possible to stably detect the steering neutral position.

[Brief explanation of the drawing]

FIG. 1 is a diagram corresponding to claims of the present invention.

FIG. 2 is a configuration diagram showing the configuration of an embodiment of the present invention.

FIG. 3 is a block diagram showing the configuration of a neutral position detection section shown in FIG. 2;

FIG. 4 is an explanatory diagram illustrating the function of a steering angle detection section.

FIG. 5 is an explanatory diagram illustrating the function of a steering angle detection section.

FIG. 6 is an explanatory diagram illustrating the function of a steering angle detection section.

FIG. 7 is an explanatory diagram illustrating the function of a neutral range determination section.

FIG. 8 is a characteristic diagram showing an example of weighting coefficients based on vehicle speed.

FIG. 9 is an explanatory diagram illustrating the function of a normal distribution determining section.

FIG. 10 is a flowchart showing a control procedure when this embodiment is implemented using a microcomputer.

[Explanation of symbols]

1 Shaft member 2 Disk member 3 Steering angle detection hole 4 Neutral range detection hole 5 Optical sensor 6 Optical sensor 7 Optical sensor 10 Steering angle calculation processing unit 12 Vehicle speed sensor

Claims (2)

[Claims] 1. Steering angle detection means for detecting a steering angle due to a rotational operation of a steering wheel; neutral range detection means for outputting a neutral range signal when a steering position falls within a predetermined steering range including a neutral steering position; a speed detection means for detecting a traveling speed of the vehicle; and a speed detecting means for detecting a vehicle speed at that time with respect to the steering angle, each time the vehicle travels a predetermined distance at the steering angle detected when the neutral range signal is output. A steering position detection device for a vehicle, comprising: weighting means for weighting; and neutral position calculation means for calculating a neutral steering position by statistically processing the weighted steering angle. 2. The vehicle according to claim 1, wherein the weighting means increases the weighting coefficient as the vehicle speed increases from low to high, and decreases the weighting coefficient when the vehicle speed reaches a predetermined vehicle speed or higher. Steering position detection device.