JPH02249001A - Arithmetic unit for digital manipulated variable - Google Patents

Abstract

PURPOSE:To obtain highly precise control performance even by means of the digital/analog converter of low cost by storing numbers which are to be raised or cut off as they are made into integers in a latch register and executing addition and correction at the time of calculating a digital code value next time. CONSTITUTION:An arithmetic processing part 10 and the latch register 11 calculate the digital code value 18 outputted to the digital/analog converter 12 by a real number, set the integer part of a numeric obtained by rounding a decimal part as an output value, store the numbers which are to be raised or cut off as they are made into the integers in the latch register 11, execute addition and correction at the time of calculating the digital code value next time. Thus, an intermediate value can virtually be outputted and highly precise control performance can be obtained even by the digital/analog converter of low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for performing before digital operation of various controllers incorporating a digital-to-analog converter.

[Conventional technology]

In recent years, with the spread of microprocessors, the number of controllers that control various machines via digital-to-analog converters has rapidly increased. The resolution of the digital-to-analog converter is determined by the control precision required, but from a cost standpoint, it is desirable to use a converter with a resolution as low as 1r. Recently, machine tools have become significantly faster and more precise.
Sir of robots etc? There is also a strong demand for a lower-cost 12-bit converter than the commercially priced 16-bit converter for yarn.

However, digital-to-analog converters naturally have a discrete value corresponding to the resolution (
It can only be set at discrete values, and there is no other way than to force the value of the middle IB between adjacent codes to match one of them. Therefore, this deviation from the true value causes problems such as deterioration of control accuracy or residual offset.

[Problem to be solved by the invention]

Conventional methods do not have a suitable means for achieving high precision control performance while using a low resolution digital-to-analog converter.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a digitally manipulated variable calculator that allows a low-resolution digital-to-analog converter to output an intermediate value virtually higher than the resolution.

[Means to solve the problem]

The digital manipulated variable arithmetic device according to the present invention is a manipulated variable arithmetic device for a controller that includes a digital-to-analog converter.
And Digital Fist Analog Hentai Machine 12 and Sir?・Ann f1
3, a motor 14, a pulse encoder 15, and a position counter 16, the arithmetic processing unit 10 and latch register 11 calculate the digital code value to be output to the digital-to-analog converter as a real number, and convert the decimal part to 4. The integer part of the number obtained by rounding down to the nearest 5 is used as the output value, and any fractions that are rounded up or rounded down due to integerization are stored in the latch register 11 and added and corrected the next time the digital code value is calculated. It is characterized by applying .

[Effect]

The arithmetic processing unit and the two registers calculate the digital code value to be output to the digital-to-analog converter as a real value, round the decimal part to the nearest 4, and set the integer part of the obtained value as the actual output value. Fractions that are rounded up or truncated due to integer conversion are corrected by adding them when calculating the next digital code value, thereby virtually making the output of the intermediate value a reasonable HQ. do.

〔Example〕

Examples of the present invention are shown in FIGS. 1 to 3.

FIG. 1 is a block diagram of an embodiment of the present invention. In FIG. 1, numeral 2 and numeral 10 are an arithmetic processing section consisting of a microprocessor, I is a digital code latch register, numeral 12 is a digital-to-analog converter (hereinafter referred to as a D/A converter), and numeral 13 is a sensor? Amplifier.

14 is a motor, 15 is a pulse encoder, 16 is a position counter, 17 is a digital operation lid, 18 is the same signal after register latch, 19 is an analog operation amount which is the output of a digital-to-analog converter, and 20 is an analog operation amount. 2 is a motor drive signal, 2 is a coupling mechanism that connects the motor shaft and the pulse encoder shaft, 22 is a rotation angle detection signal, and 23 is a motor position signal. Figure 1 shows an example of a servo system,
The present invention relates only to the digital-to-analog converter, and the configuration of other parts may be any different from that shown in the drawings.

Next, the operation of the embodiment of the present invention will be explained based on the block diagram of FIG. The arithmetic processing unit IQ performs the arithmetic operations shown in FIG. 2, outputs a digital operation amount 17, and stores a digital code in the latch register 11. digital·
The analog converter IZ converts this digital value into an analog operation t19 and outputs the signal from the server? - Inform amplifier 13. The servo·
The output signal 20 of the amplifier 13 rotates the motor 14, which in turn rotates the pulse encoder 15'f.

The signal is fed back to the arithmetic processing unit 10 as a motor position signal 23 via the rotation ID position counter 16 of the Noculus encoder.

The calculation in the calculation processing section 10 calculates the manipulated variable by calculating the deviation from the target value and this feedback value.

The specific contents are shown in Figure 2. The key point is to calculate the digital code value given to the D/A converter as a real value, and
The integer part is output to the /A converter, but the error (fraction after the decimal point) caused by rounding down to 5 must be memorized and corrected by addition when obtaining a new digital code value in the next control cycle. Make it. In FIG. 2, the calculation means of the operation lid OT converts the positioning command value shown in FIG. 1 into Pi and motor position signal 2.
3 as Pp, and K for the servo system loop.

When, OT=Kp(Pl-Pj).

Regarding the conversion coefficient TK, if the output of the D/A converter is ±10 Valt, which corresponds to a speed of ±10 m/min, then if it is a 12-bit D/A converter, the digital code is ±2048. , corresponding to this speed, TK can be calculated from TK x (±10 m/min) = ±2048.

FIG. 3 shows the relationship between the discrete values determined by the resolution of the digital-to-analog converter and the intermediate values (continuous values indicated by Δ) determined by the arithmetic unit. R, (negative value) is added to the next digital code value in order to cancel the error that will be generated this time. Therefore, if the control cycle is fast enough, the above correction work will be performed without interruption, and virtually continuous values can be output.

〔Effect of the invention〕

Since the present invention is configured as described above, it is possible to virtually output a continuous value higher than the resolution of the digital-to-analog converter, and even a low-cost digital-to-analog converter can achieve accurate control performance. It becomes possible to realize it, and it has a miserable and excellent effect.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a diagram showing the procedure of the arithmetic processing section of the device of the present invention, and FIG. 3 is a diagram showing the relationship between digital code values and true values. 10... Arithmetic processing unit, 1... Launch register, 1
2...Digital-to-analog converter, 13...Surge/amplifier, 14...Motor, 15...N7 pulse/
Encoder, 16... Flag counter Appearance agent Patent attorney Takehiko Suzue Diagram

Claims (1)

[Claims] In a controller operation amount arithmetic device with a built-in digital-to-analog converter, an arithmetic processing unit (10), a latch register (11), and a digital-to-analog converter (12) are used.
), a servo amplifier (13), a motor (14), a pulse encoder (15), and a position counter (16). The digital code value to be output is calculated as a real number, the decimal part is rounded down to the nearest 40, and the integer part of the obtained value is the output value. (11) A digital operation amount arithmetic device characterized in that the digital code value is stored and corrected by adding it when calculating the next digital code value.