JPH0674787A - Absolute position detector - Google Patents

Abstract

PURPOSE:To obtain an absolute positional signal interpolated through an absolute position detector equipped with an incremental encoder. CONSTITUTION:An absolute positional signal outputted from an absolute position detector 1 equipped with an incremental encoder is multiplied by (n) through an absolute positional signal multiplying means 2 and then delivered to an operating means 5. An interpolation signal generating means 3 generates an interpolation pulse signal having period 1/n times that of an incremental signal in synchronism therewith and then generates an interpolation signal based on the interpolation pulse signal. The interpolation signal is delivered to an operating means 5 which also receives a moving direction signal of a mobile detected through a moving direction deciding means 4. The operating means 5 executes addition or subtraction on the interpolation signal and the multiplied absolute positional signal to produce an interpolated and multiplied absolute positional signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an absolute position detecting device for detecting the absolute position of a moving body.

[0002]

2. Description of the Related Art In a control device such as a numerically controlled machine tool or an industrial robot, an absolute position detecting device is used which outputs an absolute position signal indicating the absolute position of a moving body at each sampling cycle. The conventional absolute position detection device cannot obtain position data of a moving body between samplings. Still, if the moving speed of the moving body is high, there is no particular problem when it is used for the control device. However, when the moving speed of the moving body becomes slow, even if the sampling cycle is shortened within a possible range, the difference in the value of the position data output for each sampling cycle becomes small, and the control using the output of the absolute position detection device is performed. This adversely affects the control operation of the device. Therefore, like the absolute position detecting device disclosed in Japanese Patent Laid-Open No. 1-223310, an interpolation pulse signal is generated between absolute position signals output at each sampling cycle,
Interpolation signal (interpolation data) based on this interpolation pulse signal
And an absolute position detection device for obtaining position data of a moving body between the absolute position signals by using the absolute position signal and the interpolation signal. This absolute position detection device uses an oscillator that generates a clock pulse in order to generate an absolute position signal and an interpolation pulse signal, and also creates an A-phase incremental signal and a B-phase incremental signal based on this clock pulse. , C phase origin signal is made from absolute position signal.

[0003]

The absolute position detecting device disclosed in the above-mentioned publication simultaneously detects an absolute position and generates an incremental signal, and uses other complicated circuits including an oscillator. There is. However, recently, an absolute position detector equipped with an optical or magnetic incremental encoder and outputting an absolute position signal at each sampling cycle has become easily available. Therefore, it has been strongly desired to realize an absolute position detecting device that can easily interpolate an absolute position by using an absolute position detector equipped with this incremental encoder.

An object of the present invention is to provide an absolute position detecting device which can obtain an absolute position signal interpolated by using an absolute position detector having an incremental encoder.

[0005]

As shown in the block diagram of FIG. 1, an absolute position detecting device according to the invention of claim 1 includes an absolute position detector 1, an absolute position signal multiplying means 2 and an interpolation signal generating means. It is provided with means 3, moving direction determination means 4 and calculation means 5. The absolute position detector 1 used in the present invention has an incremental encoder that outputs at least incremental signals of A phase and B phase, and outputs an absolute position signal indicating the absolute position of a moving body by a digital value of A phase and B phase. Output according to the sampling signal synchronized with one of the incremental signals. The absolute position signal multiplying means 2 multiplies the absolute position signal by n and outputs the multiplied absolute position signal to the computing means 5. The interpolation signal generating means 3 generates an interpolation pulse signal having a cycle of 1 / n of the cycle of the incremental signal in synchronization with the A phase and B phase incremental signals, based on the incremental signal, and based on the interpolation pulse signal. And generates an interpolation signal of a digital value and outputs it to the calculating means 5. The moving direction judging means 4 detects the moving direction of the moving body and outputs it to the calculating means 5. The calculation means 5 adds and subtracts the interpolation signal and the multiplied absolute position signal to output an interpolated multiplied absolute position signal. The calculating means 5 may periodically output the interpolated multiplication absolute position signal in synchronization with the interpolated pulse signal, but may output the interpolated multiplication absolute position signal only when necessary.

In the invention of claim 2, n is 2 or 4.

According to the third aspect of the present invention, there is further provided means for stopping the operation of the interpolation signal generating means when the speed of the moving body exceeds the set speed.

[0008]

According to the present invention, the position data of the moving body between samplings that cannot be detected by the absolute position detector 1 is utilized by using the A-phase and B-phase incremental signals output from the incremental encoder. For the purpose of interpolation, an interpolation pulse signal which is synchronized with the incremental signal and has a cycle of 1 / n of the incremental signal is generated from the incremental signal, and the interpolation pulse signal is used to generate the interpolation signal. The interpolation pulse signal can be easily created by using the rising or falling of the A-phase and B-phase incremental signals as a trigger signal. For example, if n = 4,
When the interpolation pulse signal is generated at a period of 1/4 of the sampling period between each sampling, the number of interpolation pulse signals (for example, "3" is simply added to the position data (for example, "100" value) indicated by the absolute position signal. When the interpolation position data is created by adding and subtracting the value of "," the interpolation position data (for example, "103")
Or the value of "97" is the position data (for example, the value of "101" or "99") indicated by the next absolute position signal.
Larger or smaller value. Therefore, if the absolute position signal is multiplied by 4, if the moving direction of the moving body is constant and the speed is constant even if the interpolation signal is generated by the interpolation pulse signal generated during sampling, in principle, the actual absolute The discrepancy between the position data and the interpolated position data will not occur.

According to the first aspect of the present invention, the absolute position signal is multiplied by n to form a multiplied absolute position signal, and the interpolation pulse signal having a period of 1 / n of the period of the A-phase and B-phase incremental signals is used as the incremental signal. To generate an interpolation signal, and add / subtract the multiplication absolute position signal and the interpolation signal according to the moving direction of the moving body by the calculating means to easily use the incremental signal to interpolate the position data (interpolation multiplication absolute position signal). ) Can be obtained.

According to the third aspect of the present invention, since the means for stopping the operation of the interpolation signal generating means when the speed of the moving body becomes equal to or higher than the set speed is further provided, useless calculation in the high speed region can be prevented.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 2 is a block diagram showing the configuration of an embodiment in which the invention of claim 1 is used for controlling a servomotor. 11
Is an absolute position detector including an incremental encoder 12, an absolute position signal generation circuit 13, and a serial transmission circuit 14. Incremental encoder 12
Is fixed to a servomotor that drives a moving body (not shown), and is necessary for detecting the incremental signals of A phase and B phase, the origin signal of C phase (not shown), and other absolute positions as shown in FIG. Output a signal. The absolute position signal generation circuit 13 internally creates a sampling signal in synchronization with the rising edge of the encoder signal from the incremental encoder 12, for example, the A-phase incremental encoder signal A, and indicates the absolute position data as a digital value in accordance with this sampling signal. Generate absolute position signal ABS. The serial transmission circuit 14 receives the absolute position signal AB according to the transmission request signal RS output from the transmission request signal generation circuit 15 in the servo amplifier 16 in the control device arranged at a distant position.
S is transmitted to the serial receiving circuit 17. As the serial transmission circuit 14 and the serial reception circuit 17, those having a signal transfer performance that completes the transmission of the absolute position signal ABS before the rising of the B-phase incremental encoder B occurs.

The transmission request signal generation circuit 15 generates the transmission request signal RS based on a signal slightly delayed from the rising edge of the incremental signal A output from the interpolation pulse signal generation circuit 18 described later. The interpolation pulse signal generation circuit 18 generates an interpolation pulse signal PS for creating an interpolation signal by using the A-phase and B-phase incremental signals A and B received from the incremental encoder 12.
In this example, the multiplication number set by the multiplication number setting circuit 19 is 4, and the interpolation pulse signal generation circuit 18 generates the interpolation pulse signal PS synchronized with the rising and falling edges of the incremental signals A and B. as a result,
The interpolation pulse signal PS is synchronized with the sampling signal and has a cycle of ¼ of the sampling signal.

When the serial reception circuit 17 detects the completion of reception of one absolute position signal from the serial transmission circuit 14, it outputs a reception completion signal ES to the absolute position signal multiplication circuit 20. The absolute position signal multiplication circuit 20 has substantially the same configuration as the shift register, and after receiving the reception completion signal ES, the received absolute position signal ABS is multiplied by the multiplication number set by the multiplication number setting circuit 19. The signal is multiplied and the multiplied absolute position signal (n × ABS) is output to the calculating means 21. Figure 3
In the example of the waveform shown in (4), the absolute position signal ABS is multiplied by 4 to obtain a multiplied absolute position signal.

Reference numeral 22 denotes a switching signal generation circuit which determines whether the speed of the servo motor (not shown) is operating in a low speed range or in a high speed range and outputs a switching signal CS. When the servo motor is operated in a high speed region where interpolation is not necessary, the switching signal generation circuit 22 gives the switching signal CS for giving a count stop command to the counter 23.
Is output. When the switching signal CS is output, the counter 2
The value C of 3 is always 0, and the absolute position detection device outputs the signal obtained by multiplying the output of the absolute position detector 11 as it is.
When the switching signal generating circuit 22 determines whether it is in the high speed region or the low speed region, the incremental signal A or B or a detection signal from a known speed detector is used. Counter 2
3 up-counts or down-counts the interpolation pulse signal PS, and outputs the count value C to the calculation means 21. The counter 23 is automatically reset every time the transmission request signal generation circuit 15 outputs the transmission request signal RS.
Reference numeral 24 denotes a rotation direction determination circuit that detects the rotation direction of the servo motor, that is, the movement direction of the moving body (not shown) from the phase relationship between the incremental signals A and B, and the servo motor rotates in one direction (forward direction). While the servo motor is rotating in the other direction (reverse direction), the high signal or the low signal is continuously output while the high signal or the low signal is continuously output. The output from the rotation direction determination circuit 24 is input to the counter 23.
When the polarity of the signal output from the rotation direction determination circuit 24 changes (for example, changes from high to low), the counter is reset by the output of the transmission request signal RS that occurs first, and then the output of the counter 23 changes. The polarity changes (eg, changes from positive to negative).

The calculating means 21 is an absolute position signal multiplication circuit 2
The multiplication absolute position signal (n × ABS) input from 0 and the count value C of the counter 23, which is an interpolation signal, are added and subtracted and output as an interpolation multiplication absolute position signal CABS. For example, when the servo motor rotates in the positive direction, the absolute position signal ABS
When the data indicated by is increased and the counter 23 counts up, the calculation means 21 calculates n × ABS + C. Further, in this state, when the servo motor rotates in the opposite direction, the counter 23 is reset by the output of the first transmission request signal RS and thereafter the counter 23 has a negative count value (-
C) may be output to perform n × ABS-C calculation. When the servo motor rotates in the positive direction, the data indicated by the absolute position signal ABS decreases and the counter 23 counts up.
The calculation of C may be performed. If the servo motor rotates in the reverse direction in this state, n * ABS + C may be calculated.

In the above embodiment, the serial receiving circuit 17, the absolute position signal multiplication circuit 20, and the multiplication number setting circuit 1
Reference numeral 9 constitutes the absolute position signal multiplication means of FIG. 1, and the interpolation pulse signal generation circuit 18, the multiplication number setting circuit 19, the counter 23 and the switching signal generation circuit 22 constitute the interpolation signal generation means 3 for rotation. The direction determining circuit 24 constitutes the moving direction determining means 4.

In the above embodiment, since the interpolation pulse signal PS is generated by using the rising and falling edges of the incremental signals A and B, the multiplication number is limited to 2 or 4, but the interpolation pulse signal generating circuit 18 It is possible to further increase the multiplication number by providing a frequency dividing circuit inside. Further, when the application of the absolute position detecting device is limited to the use in the low speed region, the switching signal generating circuit 22 is unnecessary.

Although the embodiment shown in FIG. 2 is an example in which most of the present invention is implemented by hardware, the present invention can also be implemented by software by positively using a microcomputer. FIG. 4 is a flow chart showing an algorithm for implementing a part corresponding to the absolute position signal multiplying circuit 20, the switching signal generating circuit 22 and the calculating means 21 in the configuration of FIG. 2 using a microcomputer. In this example, step ST1 realizes the absolute value signal multiplying means, and step ST2 and step ST3 realize the calculating means.

In each of the above-mentioned embodiments, the components other than the absolute position detector 11 are provided inside the servo amplifier of the control device which is arranged at a remote position. However, when the present invention is carried out, all the components are arranged in one place. Of course, you can collect them at. In that case, the serial transmission circuit 14 and the serial reception circuit 17 become unnecessary.

In the above embodiment, the arithmetic means 21 periodically outputs the interpolation multiplied absolute position signal. However, the arithmetic means is operated only when necessary to output the interpolation multiplied absolute position signal only when necessary. Of course, it is okay.

[0021]

According to the first aspect of the present invention, the absolute position signal is multiplied by n to form a multiplied absolute position signal, and an interpolation pulse signal having a cycle of 1 / n of the cycle of the incremental signal is generated to generate the interpolation signal. By making and adding / subtracting the multiplied absolute position signal and the interpolation signal according to the moving direction of the moving body by the calculation means, the interpolation position data (interpolated multiplied absolute position signal) can be easily obtained using the incremental signal.

According to the third aspect of the present invention, since the means for stopping the operation of the interpolation signal generating means when the speed of the moving body becomes equal to or higher than the set speed is further provided, useless calculation in the high speed region can be prevented.

[Brief description of drawings]

FIG. 1 is a block diagram for explaining a configuration of the present invention.

FIG. 2 is a block diagram showing an embodiment of the present invention.

FIG. 3 is a waveform diagram for explaining the operation of the embodiment of FIG.

FIG. 4 is a flowchart of an algorithm when the embodiment of FIG. 2 is implemented using a micro computer.

[Explanation of symbols]

 1, 11 Absolute position detector 2 Absolute position signal multiplying means 3 Interpolation signal generating means 4 Moving direction judging means 5, 21 Computing means 12 Incremental encoder 13 Absolute position signal generating circuit 14 Serial transmitting circuit 15 Serial receiving circuit 16 Servo amplifier 17 Serial Reception circuit 18 Interpolation pulse signal generation circuit 19 Multiplication number setting circuit 20 Absolute position signal multiplication circuit 22 Switching signal generation circuit 23 Counter 24 Rotation direction determination circuit

Claims (3)

[Claims] 1. An incremental encoder for outputting at least A-phase and B-phase incremental signals, wherein an absolute position signal indicating a digital absolute position of a moving body is used as one of the A-phase and B-phase incremental signals. An absolute position detector that outputs a synchronized sampling signal; an absolute position signal multiplying unit that multiplies the absolute position signal by n (n is a positive even number) and outputs a multiplied absolute position signal; Interpolation for generating an interpolation pulse signal in synchronization with the phase incremental signal and having a cycle of 1 / n of the cycle of the incremental signal based on the incremental signal, and generating an interpolation signal of a digital value based on the interpolation pulse signal Signal generation means, movement direction determination means for detecting the movement direction of the moving body, and movement direction determination means Depending on the direction of movement, the interpolation signal and the multiplied absolute position signal and a by subtraction is formed by and a calculating means for outputting the interpolated multiplied absolute position signal absolute position detection device. 2. The absolute position detection device according to claim 1, wherein n is 2 or 4. 3. The absolute position detecting device according to claim 1, further comprising means for stopping the operation of the interpolation signal generating means when the speed of the moving body exceeds a set speed.