JPH0322328B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic transmission control system that uses linear interpolation to obtain an approximate value of a curve.

Recently, with remarkable progress in semiconductor technology, microcomputers have been introduced into the automobile industry, and the development of automatic transmissions controlled by microcomputers, for example, is being promoted.

This microcomputer-controlled automatic transmission is based on the following control technology.

First, Figure 4 shows the relationship between the accelerator opening and vehicle speed of a car, approximated by the above-mentioned polygonal line, where the vertical axis is the vehicle speed, the horizontal axis is the accelerator opening, and is 1.
The speed region indicates the second speed region, and the symbol indicates the third speed region, indicating that there is an optimal gear selection for each speed region.

Therefore, when the driver depresses the accelerator and reaches a certain speed, when the vehicle speed yp for the accelerator opening xp at that time reaches point P in Fig. 4, the point P becomes 2.
By identifying that the vehicle is in the speed range and automatically changing the gear position from the first speed range at the start to the second speed range, this control mechanism functions as an automatic transmission.

If this control is performed by a microcomputer,
It is necessary to determine the position of the above point P using a microprocessor. Specifically, the position of the point P is
It can be seen that it is sufficient to determine whether it is on the side of straight lines γ and δ among γ and δ.

Now, the coordinates (x1, y1) of the origin γ of the straight lines γ and δ are
Assuming that the slope of the straight lines γ and δ is a, the value yp' of the straight lines γ and δ with respect to the Arcel opening xp corresponding to the point P can be determined as yp'=a(xp-x1)+y1.

Comparing the vehicle speed yp with respect to the point P and the above yp', yp'>yp, so it can be determined that the point P is on the side.

In order to effectively carry out such automatic gear change control, the microcomputer uses the microcomputer to draw straight lines in each section of the polygonal lines α, β, γ, and δ, which approximate the curve representing the "accelerator opening - vehicle speed" characteristic. Therefore, it is necessary to find it quickly.

On the other hand, when performing calculations on the microcomputer described above, since few microcomputers with a data width of about 8 bits are equipped with a division instruction, a division routine is created in software, and the division routine is used to perform each of the above intervals. The slope a of the straight line [i.e.
(y2−y1)/(x2−x1)],
There was a problem that the processing time and memory amount increased to perform linear interpolation.

One way to easily perform the above division is to select the accelerator opening degree xi in the above example so that the above division (X2 - X1) is a power of 2.
There will be restrictions on how to take it.

Therefore, when obtaining an approximate value of a curve by linear interpolation using a microcomputer, there is a need for a method that reduces the amount of memory, shortens processing time, and does not impose restrictions on how to obtain xi.

[Conventional technology]

Traditionally, as a method for finding approximate values of curves,
Linear interpolation is often used.

Figure 3A shows the method of linear interpolation in conventional automatic shift control, in which the curve m is approximated by polygonal lines α, β, γ, etc., and the respective origin coordinates (x1, y1), ( The data of x2, y2), ..., (xn, yn) are arranged as a table in the storage device as shown in Figure 3 (b).

Then, when performing linear interpolation in the intervals α and β, for the X-axis value x of the intervals α and β, y=(y2-y1)(x-x1)/(x2-x1)+y1... The interpolated value y for the above x was calculated using the interpolation formula shown in (1).

[Problem that the invention seeks to solve]

Therefore, when calculating the above linear interpolation formula (1) with a microcomputer, it is necessary to perform the division shown as (y2 − y1) / (x2 − x1), but as mentioned above, the division is 8
In a microcomputer with a bit size,
Since few devices are equipped with a division instruction, it is necessary to create a division routine using a program and use the division routine to perform the above division.

Therefore, there are problems in that the processing time and number of program steps required by the division are large.

Also, as mentioned above, as a method to simplify the division, for example, select the values of x1, x2, ... so that (x2 - x1) in equation (1) becomes a power of 2, and perform a shift operation. It is often used to divide by,
This method has a constraint that x1, x2, ..., xn must be set at intervals that are powers of 2, which makes it difficult to accurately approximate the curve with a straight line.

SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks of the conventional technology, it is an object of the present invention to provide a method for performing automatic shift control without using division.

[Means for solving problems]

The purpose of this is "accelerator opening x - vehicle speed y characteristics"
In an automatic transmission control system that determines the gear position according to =1, 2, 3,...]
is recorded in advance as a table in the storage device, the value (xi) of the accelerator opening sensor is read, and xi
a step of identifying <xp<xi+1; a step of reading yi and a slope ai for xi from the storage device; a step of calculating yp'=ai(xp-xi)+yi;
This is achieved by an automatic shift control system characterized by including a step of reading the value (yp) of the vehicle speed sensor and comparing yp' and yp, and a step of changing the gear position based on the comparison result.

[Effect]

That is, according to the present invention, in a section (x1, y1), (x2, y2) with a polygonal line approximating a curve, it is expressed as y=(y2-y1)(x-x1)/(x2-x1)+y1. Since the linear interpolation formula for Since there are no restrictions on how straight sections are taken, it is possible to perform automatic gear shift control with high precision.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.
Figure 1 is a diagram explaining the concept of the present invention, and Figure 2 is a diagram explaining the concept of the present invention.
The figure shows an example in which the present invention is applied to an automatic transmission for an automobile.

In FIG. 1, A is a diagram illustrating the method of obtaining the approximate value of the curve explained in FIG.
yn) are the origin coordinates of each section of the same polygonal line as explained in Fig. 3, and a1, a2, ..., an are data indicating the slope of each section necessary to implement the present invention. .

In the present invention, the coordinates of the above (x1, y1), (x2, y2), ..., (xn, yn) and the slopes a1, a2, ... of the straight lines passing through the coordinate points are stored on the storage device. ,
An is placed in the storage mechanism in the microcomputer as shown in Figure 1B, and the microprocessor identifies which section of input data x is in. For example, when it is identified that the origin coordinates are in an interval (x1, y1), the slope a1 of the straight line in the interval and the origin coordinates (x1, y1) are read from the storage device, and y=a1(x −x1)+y1 is performed to obtain the interpolated value y.

As is clear from the above equation, the automatic shift control of the present invention does not use division, so the processing speed for determining the interpolated value is fast, the number of processing steps is small, and there are no restrictions on how the data table can be created. There is a characteristic called .

Next, the present invention will be explained with reference to FIG.

FIG. 2(a) shows the control structure of the automatic transmission in a block diagram, and FIG. 2(b) shows its operation in a flowchart.

1 is the microprocessor (MPU), 2 is the read-only memory (ROM), and 3 is the microprocessor (MPU).
4 is a random access memory (RAM), 4 is a sensor necessary for automatic gear shift control, 41 is an accelerator opening sensor (xp), 42 is a vehicle speed sensor (yp),
5 is a gear selection actuator (GS).

The automatic shift control method according to the present invention will be described below with reference to the block diagram in A and the flowchart in B.

Step 10: Microprocessor (MPU) 1
Accordingly, the read-only memory (ROM) 2 is accessed and accelerator opening data xi (i=1, 2, 3, . . . ) is read from the data table.

Step 11: Microprocessor (MPU) 1
, read the value of the accelerator opening sensor (xp) and identify xi<XP<XI+1.

If xi<xp<xi+1, step
Skip to step 12, but if xi<xp<xi+1, move to the next step 13.

Step 12: Read-only memory (ROM) 2
Next accelerator opening data xi (i=1, 2, 3,
…) and return to step 11.

Step 13: Microprocessor (MPU) 1
Then, the read-only memory (ROM) 2 is accessed to read the interpolated value yi and the slope ai corresponding to the arcel opening data xi, and the process moves to the next step.

Step 14: Microprocessor (MPU) 1
In, random access memory (RAM) 3
Using this, calculate yp' = ai (xp - xi) + yi, and move on to the next step 15.

Step 15: Microprocessor (MPU) 1
reads the value of the vehicle speed sensor (yp) 42, identifies yp'>yp, and if yp'>yp, controls the gear selection actuator (GS) to shift the gear from the 1st gear region to the 2nd gear region. However, if yp'>yp, the gear is kept in the 1st speed range.

In this manner, according to the present invention, the operation of step 14 in the microprocessor (MPU) 1 is processed at high speed, so that the driver can press the accelerator according to the "accelerator opening - vehicle speed" characteristic of the automobile. A speed range suitable for the speed at which the pedal is stepped on is determined quickly and with a small amount of memory, and desired automatic speed change control can be performed smoothly.

〔Effect of the invention〕

As explained above in detail, the automatic shift control method of the present invention can obtain interpolated values without using division, so processing speed is faster, the amount of memory is small, and straight-line section handling is possible. Since there is no restriction in direction, there is an effect that highly accurate automatic gear change control can be performed.

Therefore, when this high-speed linear interpolation is applied to automatic shift control of an automobile, it is possible to perform high-speed, economical, and highly accurate automatic shift control.

[Brief explanation of drawings]

Fig. 1 is a diagram explaining the concept of the present invention, Fig. 2 is a diagram showing a block diagram and operation flowchart of an automatic transmission to which the present invention is applied, and Fig. 3 is a diagram illustrating a conventional automatic transmission control method. FIG. 4 is a diagram illustrating the field of application of the present invention. In the drawing, 1 is a microprocessor (MPU), 2 is a read-only memory (ROM), and 3 is a microprocessor (MPU).
4 is a random access memory (RAM), 4 is a sensor necessary to perform automatic shift control, 10 to 15 are each step of automatic shift operation, ~ is each speed range in the transmission, x is the accelerator opening, y is the vehicle speed ,
P indicates the speed range when the driver steps on the accelerator.

Claims (1)

[Claims] 1. In an automatic transmission control system that determines the gear position according to the accelerator opening x-vehicle speed y characteristic, the characteristic curve is approximated by a polygonal line, and each section of the polygonal line is represented by a straight line. The inclination ai and the origin coordinates (xi, yi) [i = 1, 2, 3, ...] of the straight line are recorded in advance as a table in the storage device, and the value (xi) of the accelerator opening sensor is read. a step of identifying xi<xp<xi+1; and a step of identifying xi<xp<xi+1;
yi and a step of reading out the slope ai, a step of calculating yp′=ai(xp−xi)+yi,
An automatic shift control method comprising: a step of reading a value (yp) of a vehicle speed sensor and comparing yp' and yp; and a step of changing a gear position based on the comparison result.