JP2002112566A - Motor controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor controller, capable of setting a basic resolution freely and precisely without increasing the number of digits of a numerator and a denominator of frequency dividing multiplication device, even if a position detector becomes an extremely high resolution, in consideration of a problem in a conventional art that an extremely large number of digits of the numerator and the denominator of the dividing multiplication device is needed, when the resolution of the position detector becomes high. SOLUTION: This motor controller is provided with a means of performing resolution conversion to an arbitrary basic traveling distance, by multiplying position data which are detected by the position detector 7 with a factor for the frequency dividing multiplication device. Noting that the position detector is resolved highly with a resolution expressed by the power of 2, the term of the power of 2 is applied to the numerator and the denominator of the factor of the dividing multiplication device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting the position of a motor and controlling the motor in accordance with a given position command.

[0002]

2. Description of the Related Art In recent years, the resolution of a position detector of a motor control device such as a servomotor has been increasingly improved, and a high-resolution position detector having a resolution of 10,000 to 130,000 per rotation for general-purpose applications. Is used. If higher precision is required, those exceeding one million resolution have been put to practical use. As described above, since the high-resolution position detector can effectively use the memory because the position data is processed by the microcomputer, and the high-resolution method inside the position detector can easily obtain the resolution of the power of 2, it is 10 times higher. Generally, a resolution having a power of 2 instead of a multiple is provided. Normally, when performing position control using a motor having a position detector, the basic resolution for positioning the target to be position-controlled, that is, the basic moving distance, is determined in consideration of the required positioning accuracy of the position control device. From the viewpoint of the simplicity of the operation calculation, it is desired that the basic movement distance be 5 μm or a rotation angle of 30 minutes or an integer that is easy to understand intuitively. Here, FIG. 2 shows an example of the position control device configuration.
Is shown. A motor 11 having a position detector 12 with a resolution of 10000 [resolution / rev] drives a 10 [mm / rev] ball screw 15 via a gear 13 with 4 teeth and a gear 14 with 11 teeth, This is a configuration for positioning 16. In this case, the resolution of the position detector is equivalent to about 0.37 μm as the moving distance of the table 16. In the case shown in FIG. 2, if the basic movement distance for positioning the table 16 is set to 5 μm, 5 μm
m is equivalent to 13.75 resolution of the position detector, and is a decimal number that cannot be expressed by the resolution of the detector.
Of course, the resolution of the position detector is 5 μm in the table moving distance.
It is possible to set the reduction ratio of the drive system on the assumption that it is adjusted to the speed, but in the first place the maximum speed, maximum and rated torque of the motor are effectively used to realize the movement speed of the drive system and the required torque. Therefore, it is difficult to make the resolution of the position detector compatible with the condition set so as to represent a good moving distance of the table.

Here, suppose that 5 μm is the position detector 13.
Equivalent to 75 resolutions, but if the basic movement distance of 5 μm is set as 14 resolutions of the position detector after rounding off to the decimal point and the position data detected by the position detector is converted into the basic movement distance, one basic movement distance That is, about 0.
An error of 091 μm occurs, and when the moving distance is increased, the errors accumulate, so that accurate positioning cannot be performed. As an example, the accumulated error when this drive system is moved by 10 mm reaches about 182 μm. The following method is often used to convert the position data detected by the position detector into the basic moving distance so that such accumulated errors do not occur. The position detected by the position detector is multiplied by a certain numerator, divided by a certain denominator, fractional calculation is performed, and if there is a remainder generated by the calculation, it is stored. Is a method for preventing the occurrence of an accumulated error by adding the remainder to the next calculation. With this configuration, the accumulated error does not occur, and the surplus generated at that time represents the steady-state error.
It can be seen that the resolution is always lower than the resolution of the position detector. The setting of the coefficient of the frequency divider / multiplier is obtained by obtaining the numerator and denominator from the reduction ratio of the driving system, the resolution of the position detector and the set basic resolution as shown in (Equation 1), and dividing the numerator and the denominator. .

[0004]

(Equation 1)

The case where the data of the position detector is divided and multiplied has been described so far. However, the position command side can be similarly configured by dividing and multiplying the data of the commanded position. That is, if the basic movement distance is 5 μm under the conditions of FIG. 2 according to the above-described example, the reciprocal of the result of (Equation 1) is divided in order to make one position command data correspond to 13.75 resolution of the position detector. Fractional calculation is performed by multiplying the position command data by the coefficient as a coefficient of the frequency multiplier, and if there is a remainder generated by the calculation, it is stored, and the remainder is added to the next calculation. Thus, the resolution conversion of the position command data to the basic movement distance can be performed without an accumulated error.

[0006]

However, in such a conventional technique, when the resolution of the position detector is increased, the number of digits of the numerator and denominator of the frequency divider / multiplier must be very large. There is. For example 2 of 17
When the basic moving distance is similarly set to 5 μm under the condition of the mechanism system of FIG. 2 in the position detector having the power of 131,072 resolution, when the coefficient of the frequency divider / multiplier is calculated according to (Equation 1), the value of the denominator Is a large value such as 22528. In consideration of processing by the microcomputer, when the resolution of the position detector is 10000 as shown in (Equation 1), this is a value that can be expressed by 6 bits of 55, whereas the position of 131,072 resolution In the case of the detector, a memory of 22528 of 15 bits is required. Further, considering the case where the resolution of the position detector is 2 to the 20th power, that is, 1,048,576, the denominator is calculated in the same manner to be 180224, which requires 18 bits of memory. Such a calculation with a large number of bits imposes a heavy load on the operation of the microcomputer, and is not practical. The present invention has been made in view of the above problems, and even if the position detector has a very high resolution, the denominator and the denominator
It is an object of the present invention to provide a motor control device capable of freely and accurately setting a basic resolution without increasing the number of digits of a numerator.

[0007]

According to the present invention, there is provided a position detector having two positions.
It is noted that the resolution is increased by exponentiation, and the configuration is such that the numerator and denominator of the frequency divider / multiplier have a power of 2 term as shown in (Equation 2).

[0008]

(Equation 2)

With such a configuration, even if the resolution of the position detector becomes very large at the power of two, the power term d on the denominator side in (Equation 2) can be set (Equation 1).
Since the resolution of the position detector which is a component of the denominator can be simply and accurately expressed, it is possible to express a fraction without increasing the number of digits of the integer term c. Also 2
The exponentiation operation can be easily realized in the microcomputer by shifting the bits, and at the same time, since the number of digits of the integer term c can be set small, the frequency division / multiplication processing can be realized by the operation with a small number of bits. This means that the computing power of the microcomputer can be effectively used for realizing other functions without using much of the computing power of the microcomputer for the frequency division / multiplication processing. Further, as an additional effect, when a setting device is provided so that the user can freely change the frequency division / multiplication function, the number of display digits of the numerator / denominator setting device of the frequency division / multiplication device can be reduced and freely. It is possible to set with high accuracy. Also, when dividing and multiplying by the position command side, since the coefficient of the frequency divider and multiplier is the reciprocal of the coefficient on the position detecting side as described above, the numerator is composed of the resolution of the position detector this time. The same effect can be obtained by setting a power-of-two term b in (Equation 2). Further, when it is appropriate that the resolution of the position detector is represented by a power of X, a similar effect can be obtained by representing the coefficient of the frequency divider / multiplier by a power of X.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention comprises a position detector for detecting a position with a power of 2 resolution, and converts the detected position data by multiplying the detected position data by a dividing / multiplying coefficient composed of a denominator and a numerator. The motor control device includes means, and the denominator / numerator has a power-of-two term as shown in (Equation 2). Further, the present invention includes a position detector for performing position detection at a power of 2 resolution, and a means for converting the resolution of the command position data by multiplying the command position data by a frequency division multiplication coefficient composed of a denominator and a numerator. The frequency multiplication coefficient is a motor control device in which the denominator / numerator has a power of 2 as shown in (Equation 3).

[0011]

[Equation 3]

Further, the present invention comprises a position detector for performing position detection at a power of 2 resolution, and multiplies the detected position data by a frequency division / multiplication coefficient composed of a denominator and a numerator to convert the resolution. Resolution conversion means, and the frequency division multiplication coefficient is 2 in the denominator / numerator as shown in (Equation 2).
At the same time as multiplying the command position data by a dividing / multiplying factor composed of a denominator and a numerator, thereby providing second resolution converting means for converting the resolution. The dividing / multiplying factor is ( As shown in Equation 3), the denominator
This is a motor control device in which the numerator has a power of two term.
Further, the present invention includes a position detector that performs position detection at a resolution of a power of a natural number X, and includes a unit that performs resolution conversion by multiplying the detected position data by a frequency division multiplication coefficient configured by a denominator and a numerator. The frequency division multiplication coefficient is (Equation 4)
As shown in (1), this is a motor control device in which the denominator / numerator has a power term of a natural number X.

[0013]

(Equation 4)

The present invention further comprises a position detector for performing position detection at a resolution of a power of a natural number X, and means for converting the resolution of the commanded position data by multiplying the data of the commanded position by a frequency division and multiplication coefficient composed of a denominator and a numerator. And the dividing / multiplying coefficient is a power controller of a natural number X in a denominator / numerator as shown in (Equation 5).

[0015]

(Equation 5)

Further, the present invention includes a position detector for performing position detection at a resolution of a power of a natural number X, and performs resolution conversion by multiplying the detected position data by a frequency division multiplication coefficient composed of a denominator and a numerator. A resolution conversion means, and the frequency division multiplication coefficient is represented by
A second resolution conversion means for converting the resolution by multiplying the data of the commanded position by a frequency division multiplication coefficient composed of a denominator and a numerator, while providing the numerator with a power term of a natural number X; The multiplication coefficient is a motor control device in which the denominator / numerator has a power term of a natural number X as shown in (Equation 5).

[0017]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of the configuration of a motor control device that performs position control. In this example, the position command side and the position detection side have a frequency division / multiplication function. When a position command is given, a numerator / denominator coefficient set in the frequency divider / multiplier A1 is calculated. Even if a surplus occurs, this surplus is stored here. The position of the motor is detected by the position detector 7, which is similarly calculated by the frequency divider / multiplier B5. A difference is obtained from these results by the adder 2, and the difference is calculated by the position controller 3 to calculate a voltage or current value to be given to the motor. These are applied to the motor by the power converter 4, and the motor operates according to the given position command. Here, if the resolution of the position detector 7 is represented by a power of 2, these frequency dividers A and B have power of 2 terms expressed by (Equation 2) and (Equation 3). No matter how large the resolution of the position detector 7 is in the power of two, the power-of-two term b,
If d, f, and h are set only to represent the resolution of the position detector 7 as necessary, accurate resolution conversion can be performed without increasing the integer terms a, c, e, and g.

When the resolution of the position detector 7 is expressed by a power of X, the frequency multiplier is provided with a power term of X as shown in (Equation 4) and (Equation 5). The effect of can be obtained.

[0019]

As described above, the present invention reduces the number of digits of the numerator and denominator of the frequency divider / multiplier even if the resolution of the position detector becomes very large by the power of 2 or the power of the natural number X. In addition, resolution conversion can be performed with high accuracy.

[Brief description of the drawings]

FIG. 1 shows a control device of the present invention.

FIG. 2 shows a positioning device.

[Explanation of symbols]

 1 frequency divider A 2 adder 3 position controller 4 power converter 5 frequency divider B 6 motor 7 position detector 8 load 10 motor controller 11 motor 12 position detector 13 gear 14 gear 15 ball screw 16 table

Claims (6)

[Claims] 1. A configuration comprising a position detector for detecting a rotational position of a motor with a power-of-two resolution, and multiplying the detected position data by a division / multiplication coefficient composed of a denominator and a numerator to convert the resolution. A motor control device comprising a motor controller having a power-of-two term in a denominator / numerator of a frequency division multiplication coefficient. 2. A position detector for detecting a rotational position of a motor at a power-of-two resolution, wherein a resolution is converted by multiplying the position command data by a frequency division multiplication coefficient composed of a denominator and a numerator. A motor control device, wherein the denominator / numerator of the frequency division multiplication coefficient has a power-of-two term. 3. A motor control device having the configuration according to claim 1 and 2. 4. A position detector for detecting the rotational position of the motor at a resolution of a power of a certain natural number X, and the detected position data is subjected to resolution conversion by multiplication by a frequency division multiplication coefficient composed of a denominator and a numerator. A motor control device having a configuration, wherein a denominator and a numerator of a division / multiplication coefficient have a power term of a natural number X. 5. A configuration comprising a position detector for detecting a rotational position of a motor at a resolution of a power of a certain natural number X, and performing resolution conversion by multiplying the position command data by a frequency division multiplication coefficient composed of a denominator and a numerator. A motor control device comprising a motor controller having a power term of a natural number X in a denominator and a numerator of a frequency division multiplication coefficient. 6. A motor control device having the configuration of claim 4 and claim 5.