JPH0743566B2 - Angle calculator - Google Patents

Description

DETAILED DESCRIPTION [Outline] An object of the present invention is to simplify the angle calculation process in a calculation device that handles angle data.

The value of the angle is a binary number with a finite bit length, and the minimum value and the maximum value that can be expressed are entered in the binary number of the expression format corresponding to the entire circumference of the angle, and overflow is ignored in normal binary operation. Calculate.

[Industrial application field]

The present invention relates to an angle calculation device that performs calculations such as four arithmetic operations on angle data.

This type of calculation is frequently performed in a navigation system that detects the moving direction of a moving body such as an automobile and adds the detected moving direction and integrates the moving distance to indicate the current position of the moving body.

[Conventional technology]

FIG. 3 is a diagram showing an example of the configuration of this navigation system. The angle signal indicating the traveling direction of the automobile is obtained by converting the output signal of the angle sensor 100 such as a geomagnetic sensor into the A / D converter 10
In step 2, it is converted into a digital signal and taken into the computer 110. The data indicating the traveling distance of the automobile is captured as a value obtained by counting the output pulses of the vehicle speed pulse sensor 104 by the counter 106. The computer 110 knows the current value by adding up the traveling distance of the automobile in consideration of the moving direction, and displays the current value on the map stored in the CD-ROM 108 and displays it on the display device 112.

Incidentally, as is well known, the traveling direction detected by the angle sensor includes some error, so that if integrated as it is, a large deviation occurs in the integrated value, which is not practical. Therefore, various methods are used to correct the current value and perform integration. For example, according to the map matching method, data indicating the direction of the road is stored together with the map data stored in the CD-ROM 108, and if the traveling direction of the vehicle matches the direction of the road within a certain range. The current value is corrected as if it were on the road.

As described above, in the navigation system, the four arithmetic operations of the angle data and the comparison operation are frequently performed, and the arithmetic operations are required to be achieved at high speed.

FIG. 4 is a flow chart showing the process of the conventional angle calculation, the (a) column shows the process of fetching data from the angle sensor 100, and the (b) column shows a typical example of the calculation. It represents a process of calculating an angle (an included angle) formed by angle data representing the directions of two straight lines.

In the calculation for handling the angle data, it is general to perform arithmetic operations such as four arithmetic operations by expressing the angle by a frequency in which the entire circumference is divided into 360 units, or a radian in which the entire circumference is 2π. Therefore, the voltage value taken in from the angle sensor (step a) is subjected to offset calculation (step b), and then multiplied by a value of (180 ° / voltage full scale) to obtain a value of −180 ° to 180 °. Converted to a value (step c).

However, since the angle has periodicity, as shown in steps (d) and (e) of column (b), -180 ° to 180 ° before and after the calculation.
Normalized in the range of ゜ (in the frequency expression) or in the range of −π to π (in the case of radian expression), or in the range of 0 to 360 ° (in the case of frequency expression) or 0 to 2π (in the case of radian expression) Otherwise, the actual estimation of the angle (judgment of coincidence, judgment of size, etc.) will be erroneous.

[Problems to be Solved by the Invention]

As described above, conventionally, since it is necessary to perform normalization before and after the calculation, there is a problem that the number of program steps increases and the calculation time also increases.

Therefore, it is an object of the present invention to provide an angle calculation device that does not require such an angle normalization process.

[Means for Solving the Problems]

FIG. 1 is a block diagram showing the principle of the present invention. In the figure, the angle calculation device of the present invention is an angle value represented by a numerical value by the scaled number system of finite digits, and represents the minimum value to the maximum value that can be represented by the scaled number system of finite digits. The angle input means 10 for inputting an angle value expressed in an expression form relatively corresponding to the entire circumference of the angle, and at least one of the data in the expression form input by the angle input means 10 as the input An angle calculating means 20 is provided for performing an operation ignoring carry from a digit and outputting an angle value in the expression format.

The angle value is a binary number represented by 2's complement, and the minimum value that can be expressed corresponds to an angle of -180 ° and the maximum value is an angle of 1.
A structure corresponding to 80 ° is preferable.

Further, the angle value is an unsigned binary number, the minimum possible surface value corresponds to an angle of 0 °, and the maximum value is an angle of 360 °.
It is also preferable to adopt a configuration that substantially corresponds to °.

[Work]

By using the expression form of the angle value that proportionally corresponds to the entire circumference of the angle from the minimum value that can be expressed with a finite digit to the minimum value, by performing the operation ignoring the carry (overflow) from the finite digit. , The angle is automatically normalized,
The angle calculation process is significantly simplified.

〔Example〕

An example in which the present invention is applied to the navigation system described in FIG. 3 will be described below.

Similar to FIG. 4, FIG. 2A shows a process of fetching data from the angle sensor 100, and FIG. 2B shows a process of calculating an included angle of two straight lines as a typical example of calculation. ing.

The difference from FIG. 4 in the data acquisition process shown in the column (a) is that the conversion is performed by multiplying the value of (2 ¹⁵ / voltage full scale). By doing this, when the angle from the reference direction is (180-180 / 32768) °, the 16-bit binary number in 2's complement representation is the maximum value that can be represented.
16 converted when converted to 32767 (2 ¹⁵ -1) and -180 °
The binary number of the two's complement representation of the bit is converted into −32768 (= −2 ¹⁵ ) which is the minimum representable value. Similarly, CD-ROM1
All angle data stored in 08 (Fig. 3) is also stored at this scale.

Then, in the subsequent calculation, when the calculation result is an angle value, it is always represented by a 16-bit two's complement expression, and carry of 16 bits or more is ignored.

By doing so, as shown in FIG. 2 (b),
The normalization process (steps d and e) required in the column (a) of FIG. 4 is unnecessary.

The method of expressing the angle of -180 ° to 180 ° by the two's complement expression of -2 ^n-1 to 2 ^n-1 -1 has been described above.
It is also possible to represent 0 ° by an unsigned binary number (0 to 2 ⁿ -1), and the same effect can be obtained.

〔The invention's effect〕

As described above, according to the present invention, since it is not necessary to perform normalization before and after calculation, the following effects can be obtained in addition to the effect of reducing the number of program steps and increasing the processing speed.

Since it is a fixed decimal point type integer operation, the operation routine is simple and the processing is fast.

When expressing the angle data in 2 directions of N, S, 4 directions of N, E, S, W, or 8 directions of N, NE, ..., simply use 1, 2 or 3 bits from the highest position of the angle data. Just take it.

[Brief description of drawings]

 FIG. 1 is a diagram showing the principle configuration of the present invention, FIG. 2 is a flow chart showing an embodiment of the present invention, FIG. 3 is a diagram showing an example of a navigation system, and FIG. 4 is a conventional angle calculation process. In the flow chart and figure, 10 ... Angle input means, 20 ... Angle calculation means.

Claims (3)

[Claims] 1. An angle value expressed as a numerical value by a finite digit scale notation method, wherein a minimum value and a maximum value that can be expressed by the finite digit scale notation method are proportional to the entire circumference of the angle. Angle input means (10) for inputting an angle value expressed in a corresponding expression format, and at least one of the data of the expression format input by the angle input means (10) as an input And an angle calculation means (20) for outputting an angle value in the expression format by performing an operation ignoring the carry of the angle calculation device. 2. The angle value is a binary number in a two's complement representation, the minimum representable value of which corresponds to an angle of -180 °, and the maximum value of which corresponds to an angle of 180 °. Angle calculator. 3. The angle calculation device according to claim 1, wherein the angle value is an unsigned binary number, the minimum value that can be expressed corresponds to an angle of 0 °, and the maximum value thereof corresponds to an angle of 360 °.