JPH02105015A - Detector for absolute position of rotary body - Google Patents

Abstract

PURPOSE:To measure in high accuracy and resolution with a simple constitution by deciding absolute position signals from digital position signals through each of two-pole and multi-pole resolvers directly connected with resolving shafts. CONSTITUTION:The two-pole resolver 1A is connected to the revolving shaft 2A and the multi-pole resolver 1B is connected to the revolving shaft 2B which is coaxial with the shaft 2A, and from corresponding resolver/digital converters 4A, 4B, rotating position signals with 4 bits, etc., which are the signals in high accuracy and resolution for every section made by equally dividing one revolution of the resolver 1B in accordance with the number of pole, are outputted. Then, by a decision circuit 5, +1 or -1 to be added to the upper 2 bits of the output from the converter 4A is decided for the figure adjustment in accordance with data from the converter 4A for the 2nd bit from the lower and an input of the signal for the upper 2 bits from the converter 4B. The measurement is made by the signal indicating a section number forwarded from the converter 4A and the signal for rotating position within the section forwarded from the converter 4B.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an absolute position detection device for a rotating body that uses a resolver to detect the absolute position of a rotating body.

(Prior Art) As a conventional absolute position detecting device, a configuration as shown in FIG. 4 is known. In FIG. 2 is the rotating shaft of the resolver 1 which is directly connected to the rotating shaft of the rotating body (not shown) which is the object to be detected. 3 is the excitation of the resolver 1. An excitation circuit for passing an excitation current through the winding, 4 is a resolver/digital converter (hereinafter referred to as an R/D converter), which converts the output signal (analog signal) of the resolver 1 into a digital signal. . Note that since the R/D converter 4 is also well known, detailed explanation thereof will be omitted.

In such a device, when the rotating shaft 2 rotates, an angular amount proportional to the rotation angle θ of the rotating shaft 2 is obtained from the output terminal of the R/D converter 4 as a digital signal. Therefore,
From the output of the R/D converter 4, the absolute position of the rotating body directly connected to the rotating shaft 2 (the angular amount indicating how far it has rotated from the reference point) can be determined.

(Problems to be Solved by the Invention) In the absolute position detection device having the configuration shown in FIG. 4, in order to obtain the absolute position M (angle) of the rotating body with high precision and high resolution, it is necessary to The R/D converter 4 needs to have high accuracy that meets this requirement, and high resolution that meets that requirement.

However, increasing the accuracy of the output signal of the resolver 1 and the resolution of the R/D converter 4 beyond a certain value not only leads to a significant increase in costs, but also is subject to constraints due to manufacturing limitations, and becomes difficult. Therefore, in the past, there was a problem that it was not possible to obtain an absolute position detection device with high accuracy and high resolution due to various restrictions.

The present invention was proposed to solve the above problems, and
The objective is to provide a high-precision, high-resolution absolute position detection device that is low cost and free from manufacturing constraints.

(Means for Solving the Problems) In order to achieve the above object, the present invention includes a first resolver directly connected to the rotating shaft of a rotating body, and a first resolver that converts the output signal of the first resolver into a digital signal. a first R/D converter that converts the position signal into a position signal, and a second R/D converter that is directly connected to the rotation axis of the first resolver and has more poles than the first resolver.
resolver.

a second R/D converter that converts the output signal of the second resolver into a second position signal as a digital signal, and calculates the absolute position of the rotating body from the first and second position signals. The third position signal shown in FIG.

(Function) In general, if the number of magnetic poles of the resolver is increased, the R/D converter will receive (360 degrees) during one rotation (360 degrees) of the rotating body.
It is possible to obtain a digital angle signal corresponding to the Xn) variation (here, n=number of magnetic poles/2). Therefore, R/
Even without increasing the resolution of the D converter, it is possible to obtain an angle signal with approximately n times higher precision and resolution by making the resolver multipolar.

However, in this case, the output signal of the R/D converter outputs an angle signal corresponding to n rotations during one rotation of the rotating body, so
In view of the fact that it is currently impossible to know the absolute position (angle) of a rotating body unless it is possible to determine which rotation the angle signal is, the present invention uses a multipolar resolver as a second resolver. The current rotation number of the output signal (second position signal) of the second R/D converter connected to By determining from the output signal (first position signal) of the /D converter (first R/D conversion Mh) and obtaining a third position signal indicating the absolute position of the rotating body, equivalently high precision can be achieved.・Enables high-resolution absolute position detection.

(Example) An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows the configuration of this embodiment, and in the figure,
IA is a two-pole resolver as a first resolver, IB is a multi-pole, 16-pole (n=8) resolver as a second resolver, and 2A is a resolver I directly connected to a rotating body (not shown).
A rotating shaft; 2B a rotating shaft of a resolver IB directly connected to the rotating shaft 2A; and 3' an excitation circuit for exciting the resolvers LA and IB.

4A is a first R/D converter that outputs a first position signal as a 4-bit digital signal, and 4B is a second R/D converter that has a 4-bit angular resolution and outputs a second position signal. /D converter 5 receives the second lowest bit of the output signal of the R/D converter 4A and the upper two bits of the output signal of the R/D converter 4B, and forms a truth table to be described later. Perform digital processing based on (Table 1) and R/D
+1 or -1 to the upper 2 bits of the output signal of converter 4A
6 is an R/D discriminator circuit that generates data for adding
The upper 2 bits of the output signal of the converter 4A excluding the lower 2 bits
This is an adder circuit into which the bit and the 2-bit output signal of the discriminator circuit 5 are input and these are added.

Here, the angular resolution of the R/D converter 4A will be explained. The multi-pole resolver IB on the input side of the R/D converter 4B is 1
Since it has 6 poles, the angular resolution of the R/D converter 4A is 36
It is 1/16 of 0 degrees, that is, 1/24 of 360 degrees. In this case, the angular resolution is referred to as 4 bits. The R/D converter 4B is a 4-bit R/D converter. In addition, R
The number of bits of the /D converter 4B is not necessarily the same as that of the R/D converter 4A.
There is no need to make it the same as that of .

Furthermore, in FIG. 1, the output signal of the R/D converter 4A will be referred to as an ABS signal, and the output signal of the R/D converter 4B will be referred to as an INC signal. To simplify the explanation, it is first assumed that both the ABS signal and the INC signal have zero error relative to their true values.

FIG. 2 shows each section O to 7 when the rotation angle (360 degrees) when the rotation axes 2A and 2B of the resolvers LA and IB make one rotation is divided into eight equal parts. In this case, the width of each section is 360/8 = 45 degrees.Figure 6 shows the waveform obtained by analog conversion of the ABS signal and INC signal (both digital signals) and the digital value of the ABS signal. , since the multipole resolver IB has 16 poles, I
One period of the NC signal is 45 degrees. Note that the INC signal also has a stepped waveform like the ABS signal (in this case, since the R/D converter 4B for the INC signal is 4 bits, one cycle or one section (45 degrees) has 16 steps). is shown as a straight line in FIG. 2 for convenience.

Next, the angle detection accuracy of the ABS signal is excellent (360/4n).
When there is an error within a predetermined range, such as in
=8) will be explained.

Figure 3 shows the vicinity of section 0 in Figure 2 when there is the above-mentioned error. The range (0-a)' that they can take is calculated from .

(o − b )' is shown. In addition, A in the figure
The angular range of the part B and B is one quarter of the true value of each interval.
It is.

In Fig. 3, if the true position is in section A of section 7, the section value of that point obtained from the ABS signal is section O.
There are two cases: one in section 7 and the other in section 7. If this continues, the true position will be in section O2 and section 7 based on the ABS signal value.
It is not possible to directly determine in which interval it is located.

However, if the true position is in part A, the following two
Two conditions are always met.

■If the section calculated from the ABS signal is section 0,
The data value of the ABS signal at that time is in the first half of the O interval (
0-a), that is, the least significant bit of the data value of the ABS signal is O.

■The data of the INC signal at this time is one cycle of the INC signal (
45 degrees) into four equal parts (33, 75 to 45
degree). That is, the upper two bits of the data value of the INC signal are "11".

Therefore, when the true position is in part A (the true interval is 7), even if the value obtained from the ABS signal indicates the 0 interval, it is possible to correct it correctly by using this relationship. becomes. Furthermore, the same can be considered in the case where the true position is in part B.

Table 1 shows an example of a truth table for implementing the discrimination method using the above relationship by the discrimination circuit 5.

(Hereinafter, blank spaces) Table 1 In Table 1 above, the '□' portion indicates that the ABS signal is output as is.

That is, the discrimination circuit 5 either outputs the ABS signal as is or adds +1 or - to the ABS signal based on the least significant bit of the ABS signal and the upper two bits of the INC signal.
Data for adding a data value of 1 is created and output to the adder circuit 6.・Then, a 7-bit high-resolution third position signal is generated by the 3-bit output signal from the adder circuit 6 and the 4-bit output signal from the R/D converter 4B, and the rotation is controlled by this position signal. The absolute position of the body will be detected. Note that since it is easy to implement the discriminating circuit 5 based on the truth table shown in Table 1, a detailed explanation of the configuration of the discriminating circuit 5 will be omitted.

In the explanation so far, the error A of the INC signal has been treated as zero. In general, the ABS signal:
Even though the precision of the resolver and the number of bits of the R/E conversion signal are the same, the error in the NC signal is 1/n (n = number of magnetic poles/2), so
In many cases, it can be ignored, but if it is necessary to consider the error in the INC signal, the AB
This can be dealt with by tightening the accuracy of the S signal C.

Further, in the above embodiment, the case where there are 161 multi-pole resolvers has been described as an example, but the same consideration can be given to cases where there are two resolvers with other number of poles.

(Effects of the Invention) As described above, according to the present invention, by matching the first and second C resolvers and their corresponding R/D converters, it is possible to use resolvers with the same angular accuracy as conventional ones. Also, the angular accuracy of the multi-pole resolver can be increased to about n times the magnetic pole angle divided by 2, and a high-precision and high-resolution C1 absolute position detection device can be realized at a relatively low cost. Also.

At that time, there are no various manufacturing restrictions1
There are other effects.

[Brief explanation of the drawing]

[Figure 1 is a configuration diagram of an embodiment of the present invention, Figures 2 and 3 are
The figure shows its operation, and FIG. 4 is a configuration diagram showing a conventional example. + IA, IB...Resolver 2A
, 2B... Rotating shaft 3'... Excitation circuit

Claims (1)

[Claims] A first resolver directly connected to the rotating shaft of the rotating body, and a first resolver that converts the output signal of the first resolver into a digital signal.
a first resolver/digital converter that converts the position signal into a position signal; a second resolver that is directly connected to the rotation axis of the first resolver and has more poles than the first resolver; The second output signal as a digital signal.
a second resolver/digital converter that converts the position signal into a position signal, and obtains a third position signal indicating the absolute position of the rotating body from the first and second position signals. Absolute position detection device.