JPH03183911A - Digital resolver - Google Patents

Abstract

PURPOSE:To improve the dynamic characteristics of control by providing a rotary encoder and a 1st and a 2nd read-only memory. CONSTITUTION:The rotary encoder 12 consists of a rotatable magnetic recording medium 1, sensors 4, 5a, and 5b which are arranged opposite the medium 1, and a signal processing circuit (magnetic pole counting circuit) 6 which outputs absolute angle data corresponding to the angle of rotation from the presence position of a sensor to the origin of the medium 1. Then the 1st read-only memory (ROM) 14 uses the absolute angle data outputted by the encoder 12 as an address to output sine data corresponding to the sine value of the corresponding absolute angle. Further, the 2nd read-only memory (ROM) 15 uses the absolute angle data outputted by the encoder 12 as an address to output cosine data corresponding to the cosine value of the corresponding absolute angle. Consequently, the resolver is used to detect, for example, the arm tip position of an industrial robot, thereby realizing fast, real-time continuous track control over the robot.

Description

Detailed Description of the Invention "Field of Industrial Application" This invention is applied to detecting the arm tip position of an industrial robot, etc., and is a digital device that outputs digital data corresponding to the sine and cosine values of the detected angle. It is related to resolvers.

``Prior Art'' As is well known, a conventional analog resolver has a pair of stator windings S , , S , which are wound around the stator orthogonally to each other, as shown in FIG. , a pair of rotor windings R+ wound on the rotor so as to be orthogonal to each other,
R2, and these stator windings S , , S ,
The rotation angle α is detected by utilizing the fact that the coupling between the rotor and the rotor winding R1R2 changes depending on the rotation angle α of the rotor with respect to the stator. In this case, stator windings S I and S 2 are used as primary windings, and an alternating current voltage e is applied to them.
When l + 82 is applied, the following equations (+) and (2) are obtained from the rotor windings R, and R2 according to the rotation angle α of the rotor.
The induced voltages E 2 , , E 2 shown in FIG.

E, = e1sina + e2-cosa - (1)
E2=e1cosα−e2・sinα=−−(2
) As can be seen from these equations, the resolver can be used not only as a simple angle detector, but also for coordinate transformation and trigonometric function calculations. Furthermore, in order to solve the problem of wear and tear on the slip rings and brushes used in the electrical connection parts of the rotor, a brushless structure has also been developed.

By the way, the output of the above-mentioned conventional resolver is an analog signal, and there is a limit to the detection accuracy of the resolver itself. There were problems in applying it to continuous trajectory control of industrial robots, etc.

Therefore, conventionally, as a means for detecting the arm tip position of an industrial robot, a rotary encoder that can obtain digital absolute angle data corresponding to the detected angle of a joint has been mainly used. In this case, for example, as shown in FIG. 6, a multi-rotation type rotary encoder 55 is connected to one end of the drive shaft 51 of the servo motor 50, and a reducer having a high reduction ratio is connected to the other end of the multi-rotation drive shaft 51. (for example,
harmonic gear, etc.) 52 are connected. and,
The rotation of the drive shaft 51 of the servo motor 50 is reduced by a reducer 52 and transmitted to the robot arm 54 via a load shaft 53.

"Problems to be Solved by the Invention" Generally, in industrial robots, when determining the coordinates of the tip of the robot arm 54 by digital calculation processing, the rotation angle of the joint that is the center of rotation of the robot arm 54, i.e. The sine and cosine values of the joint angles are required. Methods for calculating the sine and cosine values include: (1) calculating the sine and cosine values from the absolute angle data from the rotary encoder 55 by Taylor expansion; A method is used in which the sine and cosine values of several angles are stored in advance in a memory, and the sine and cosine values of the angle between each point are determined by interpolation.

However, the above method (2) has the problem that high-speed real-time control of the robot, such as high-speed positioning of the robot arm 54, cannot be realized because the arithmetic processing for performing the Taylor expansion requires a long time. In addition, although the above method (■) is currently widely used for controlling industrial robots, it requires considerable time for interpolation calculation processing, so when performing high-speed real-time control, it is difficult to improve the dynamic characteristics of control. The problem was that I couldn't do it.

Furthermore, as shown in FIG. 6, in the configuration in which a multi-rotation type rotary encoder 55 is connected to one end of the rotating shaft 51 of the servo motor 50, backlash of the reducer 52 and load shaft There has been a problem in that the position of the tip of the robot arm 54 cannot be accurately detected by the rotary encoder 55 due to factors such as twisting of the robot arm 53 .

This invention was made in view of the above-mentioned circumstances, and its purpose is to calculate the sine value of the absolute angle from the digital absolute angle data output from the rotary encoder without performing any negative calculation processing. An object of the present invention is to provide a digital resolver that can instantly obtain sine data corresponding to a cosine value and cosine data corresponding to a cosine value.

"Means for Solving the Problems" In order to solve the above-mentioned problems, the present invention provides a rotatable recording medium on which a pitch signal is recorded at a constant repetition period along a predetermined circular orbit, and a sensor that is arranged opposite to detect the pitch signal, and outputs absolute angle data corresponding to a rotation angle from the location of the sensor to the origin of the recording medium based on the pitch signal detected by the sensor. a rotary encoder comprising a signal processing circuit; a first read-only memory configured to output sine data corresponding to the sine value of the corresponding absolute angle using the absolute angle data output from the rotary encoder as an address; A second device that uses the absolute angle data output from the rotary encoder as an address and outputs cosine data corresponding to the cosine value of the corresponding absolute angle.
It is characterized by comprising a read-only memory.

"Operation" According to the above configuration, using absolute angle data as an address,
Since the first and second read-only memories are provided to output sine and cosine data corresponding to the sine and cosine values of the corresponding absolute angles, it is possible to read the -cut from the digital absolute angle data output from the rotary encoder. It is possible to immediately obtain sine data corresponding to the sine value and cosine data corresponding to the cosine value of the absolute angle without performing calculation processing.

Embodiment j An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram not showing the configuration of a digital resolver according to an embodiment of the present invention. In this figure, reference numeral 1 denotes an annular magnetic recording medium, which is rotatably supported along the circumferential direction (in the direction of arrow M shown in the figure) by a special bearing (not shown). An origin track 2 and a pitch signal track 3 are provided in parallel over the entire circumference of the outer peripheral surface of the magnetic recording medium l. And on this origin track 2,
Magnetic information is recorded as an origin signal only at one location on the magnetic recording medium 1, which is the origin 1a, and magnetic information with a constant wavelength λ is repeatedly recorded as a pitch signal on the pitch signal track 3. 4 and 5 a, 5
b is a magnetic sensor formed by forming a magnetoresistive element on a glass substrate. Here, the magnetoresistive element is made of an element material that produces a so-called magnetoresistive effect, a phenomenon in which the specific resistance changes depending on the strength of the magnetic field when placed in a magnetic field. Using this, the origin signal recorded on the origin track 2 and the pitch signal recorded on the pitch signal track 3 are read.

Further, the magnetic sensors 5a and 5b are arranged along the moving direction M of the magnetic information medium I (1/4 above m) λ (however, m
are spaced apart from each other by an integer), and are arranged opposite to the pitch signal track 3 with an appropriate gap therebetween.

The resistance value of the magnetoresistive element patterns of the magnetic sensors 5a and 5b changes depending on the magnetic field received from the pitch signal track 3, and as a result, the resistance value changes depending on the magnetic sensor positional relationship.
Novel signals are now available. That is,
The interval of the magnetic information I period on the pitch signal track 3 is θ−
When 0 to 2π, the magnetic sensor 5a generates a substantially sinusoidal waveform,
A substantially cosine wave-like level signal is obtained from the magnetic sensor 5b. When the pitch signal track 3 moves relative to the magnetic sensors 5a and 5b, two-phase pseudo-sine wave detection signals sin θ (A phase) and cos θ with a phase shift of 7r/2 are generated from the magnetic sensors 5a and 5b. (B
phase) is obtained.

6 is a magnetic pole counting circuit, and waveform shaping circuits 7, 8 and 9
, direction discrimination circuit 10 , and uptown counter 11
It consists of. In the waveform shaping circuits 7 and 8, the A-phase and B-phase detection signals are respectively shaped into stages and output. In this case, A
The phase pulse Pa and the B-phase pulse Pb have a phase of π.
It becomes a rectangular wave shifted by /2, and when the rotation direction of the magnetic recording medium 1 is in the positive direction, the A-phase pulse Pa advances, and when it is in the negative direction, the B-phase pulse I) b advances. . The direction determining circuit IO determines the direction, for example, depending on whether the level of the phase pulse Pb is H'' or L'' at the rising edge of the A-phase pulse Pa.

The output signal Sw of this direction discrimination circuit 10 is connected to the up/down direction discrimination signal input terminal U of the up/down counter 11.
/ Supplied to D. On the other hand, the A-phase pulse Pa output from the waveform shaping circuit 7 is introduced as a manual count signal of the up/down counter 11 (in this case, it may be the B-phase pulse signal Pb output from the waveform shaping circuit 8). . The counter 11 is configured to switch the count mode up or down by the signal SW.
A phase pulse Pa is counted. In this case, for example,
Up-counting is performed when the magnetic recording medium 1 is rotating in the positive direction, and down-counting is performed when it is rotating in the negative direction.

On the other hand, each time the origin 1a of the magnetic recording medium 1 passes the installation location of the magnetic sensor 4, the origin signal recorded at the origin is detected by the magnetic sensor 4, and this is transmitted to the origin via the waveform shaping circuit 9. becomes pulse Pz, counter 11
It is designed to be supplied to the reset terminal R of. As a result, the counter 11 indicates that the origin 1a of the magnetic recording medium 1 is
It is reset every time it reaches the installation location of the magnetic sensor 4.

Therefore, the count value N of the counter 11 is calculated from the time when the origin 1a of the magnetic recording medium 1 passes through the installation location of the magnetic sensor 4 up to the present time.
The number of magnetized sections of the pitch signal track 3 that have passed over b (
The value corresponds to the number of magnetic poles).

That is, the count value N is determined by the rotation of the magnetic recording medium 1,
If the origin 1a moves to Ia' as shown in the figure, the value indicates the rotation angle (absolute angle) α.

Then, the count value N of this counter 1.1 is output as absolute angle data.

As described above, the rotary encoder 12 that outputs absolute angle data corresponding to the rotation angle α of the magnetic recording medium 1 is configured. In this case, the wavelength λ of the pitch signal recorded on the pitch signal track 3 is determined according to the required resolution (number of angular divisions) of the rotary encoder 12, and the number of bits of the counter II and the count value N are determined accordingly.
The range of is determined. In this embodiment, the count value N becomes 0 as the magnetic recording medium 1 rotates 180 degrees.
~2n (where n is an integer), and the number of bits of the counter 11 is (n+1
) bit, and the wavelength λ is also determined accordingly.

Next, in FIG. 1, 14 uses the 2n+1 bits of absolute angle data (count value N) output from the rotary encoder I2 as an address, and outputs sine data SINα corresponding to the sine value of the corresponding absolute angle α. first data conversion ROM (read only memory), 15
is 2 n+1 output from the rotary encoder 12
This is a second data conversion ROM that uses bit absolute angle data (count value N) as an address and outputs cosine data CO8α corresponding to the cosine value of the corresponding absolute angle α.

These data conversion ROMI4 and 15? This is the second
As shown in figures (a) and (b), each address 0 to 2
For each n+1, the required data (2° in two's complement representation)
resolution) is stored. That is, as shown in FIG. 2(a), the first data conversion ROM+4 has the following formula (3) for each address in the range of addresses 0 to 2n.
The calculated numerical values are each written in signed n-bit representation using two's complement representation.

2 n-1・5in (180'・(address))...
... (3) Similarly, address (2"+1) ~ 2
For each address in the range n+1, a numerical value 2 calculated by the following equation (4) is written in two's complement representation (signed n bits).

Further, the second data conversion ROM 15 contains addresses O to 2n-1 and (2n
For each address in the range from -1.3+1) to 2n+1, a numerical value calculated by the following equation (5) is written in signed n-bit representation using two's complement representation.

Similarly, for each address in the range of addresses (2°-'10i) to (2n minus 3), the numerical value calculated by the following equation (6) is expressed in two's complement (signed n Each bit is written in a bit) representation.

As a result, as shown in FIG. 3, when the count value N (absolute angle data) changes in the range of 0 to 2n+1 in response to a change in the absolute angle α of the magnetic recording medium I, 4- correspondingly, 1st data conversion ROM+4
-1) Cosine data CO8α (+2''-'~2''-') is output from the second conversion ROM]
Ru.

According to ``2'', signed n-pi in two's complement notation)・
Sine data SINα and cosine data COS using the expression method
A digital resolver that outputs α is configured.

As described above, the first data conversion ROMI4 outputs the sine data SINα, and the second data conversion ROMI4 outputs the cosine data COSα.
The data conversion ROM 15 has been shown as an example in which each data is written in two's complement representation (signed II beep), but these are not limited to two's complement representation, and other methods may also be used. For example, by adding or demodulating the polarity code using an appropriate method such as offset binary or straight binary (in this case, the polarity code is added by another means), any binary representation can be obtained. It goes without saying that the method can be similarly applied.

According to the embodiment described above, the sine data SINα and the cosine data CO6α corresponding to the sine value and cosine value of the absolute angle α are obtained from the absolute angle data output from the rotary encoder 12 without performing the -cut calculation process. can be obtained instantly. Therefore, by using it to detect the arm end position of an industrial robot, etc., conventional digital calculation processing such as Taylor expansion and interpolation calculation is no longer necessary, and continuous trajectory control of the robot can be realized at high speed in real time. . As a result, by directly attaching the above-mentioned digital resolver to the load shaft 53 downstream of the reducer 52 of the industrial robot shown in FIG.
The position of the tip can be determined accurately.

Next, an application example of the digital resolver according to the above-described embodiment will be described. Such a digital resolver can be used not only for industrial robots but also for surveying equipment and the like. For example, as shown in FIG.
After determining the baseline length ■7 between and 8, at measurement point A,
The angle α from the measurement point B to the point to be measured C is measured using the surveying optical instrument equipped with the digital resolver described above, while at the measurement point B, the angle β from the measurement point A to the point to be measured C is measured as described above. By substituting the sine and cosine values of the detection angles α and β obtained from the digital resolver into the following equations (7) and (8), By simple calculation of addition, subtraction, multiplication, and division, the coordinates (x, y
) can be quickly determined.

...... (7) ...... (8) In the above-mentioned embodiments, a case where a magnetic recording medium and a sensor are used is explained as an example, but an optical method or other methods may also be used. Exactly the same effect can be obtained by applying.

"Effects of the Invention" 6 - As explained above, according to the present invention, the sine and cosine values of the absolute angle can be calculated from the absolute angle data output from the rotary encoder without performing any -cut calculation processing. It is possible to instantly obtain sine and cosine data corresponding to ,
Continuous trajectory control of the robot can be realized at high speed in real time.
The effect is that the dynamic characteristics of control can be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a digital resolver according to an embodiment of the present invention, FIG. 2 is a diagram for explaining the data contents stored in the data conversion ROM of the embodiment, and FIG. 3 is a diagram showing the same. A diagram for explaining sine data and cosine data output in the embodiment, FIG. 4 is a diagram for explaining the present invention in detail, FIG. 5 is a circuit diagram showing the configuration of a conventional analog resolver, FIG. 6 is a schematic configuration diagram for explaining an example of application of a rotary encoder to a conventional industrial robot. ■...Magnetic recording medium, 2...Origin track, 3 1,. 3-...Pitch signal track, 4
．． 5a, 5b, 5a+, 5b+, 5at, 5bz-magnetic sensor, 6...Magnetic pole counting circuit (signal processing circuit)
, 12.42...Rotary encoder, 14
. . . 1st data conversion ROM (first read-only memory), 15 . . . 2nd data conversion ROM (second read-only memory).

Claims (3)

[Claims] (1) A rotatable recording medium on which a pitch signal is recorded at a constant repetition period along a predetermined circular orbit, a sensor arranged opposite to the recording medium to detect the pitch signal, and a sensor that detects the pitch signal; a rotary encoder comprising a signal processing circuit that outputs absolute angle data corresponding to the rotation angle from the location of the sensor to the origin of the recording medium based on the pitch signal; and an absolute angle output from the rotary encoder. a first read-only memory that outputs sine data corresponding to a sine value of a corresponding absolute angle using data as an address; and a first read-only memory that outputs sine data corresponding to a sine value of a corresponding absolute angle using data as an address; A digital resolver comprising: a second read-only memory that outputs corresponding cosine data; (2) The digital resolver according to claim 1, wherein the recording medium is magnetic. (3) The digital resolver according to claim 1, wherein the recording medium is an optical type.