JPH0721505B2 - Angle error measuring device - Google Patents

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reduction gear angular error measuring device, and more particularly to a device for accurately measuring a reduction gear angular error used in various robots and the like. (Prior Art) Generally, the rotational driving force of a motor or the like is often used after being reduced to a desired rotational speed by various speed reducers. Fluids, gears, belts, etc. are used as the medium for deceleration, and widely used mechanical reducers include small diameter gears on the high-speed drive shaft and large diameter gears on the low-speed driven shaft. There is one that reduces the rotation speed due to the meshing. As described above, the rotational driving force of the motor or the like is reduced by the speed reducer and is used in various machine tools. Therefore, in order to improve the working accuracy of these machine tools, it is of course necessary to improve the accuracy of the speed reducer. Accuracy of the reducer (angle error)
Need to be measured accurately. Particularly, in recent years, extremely high accuracy has been required for robot positioning and the like, and the advent of a device that can detect an angle error more accurately and easily is awaited. Conventionally, as this kind of angle error measuring device, it is general to measure manually by using a gauge, for example, and in this case, is the output angle relative to the input angle output theoretically (for example, deceleration? When trying to measure the angular error of the speed reducer with the ratio i = 1/100, the angular error is detected by measuring with a gauge whether the output is 1 ° for an input of 100 °. (Problems to be Solved by the Invention) However, such a conventional angle error measuring device has the following problems because the angle error is manually measured by using a gauge or the like. It was (1) Since the measurement is performed with a gauge, etc., there is a limit to the accuracy of the measurement, and it is said that the accuracy (high resolution) is sufficient when measuring the angular error of a speed reducer used in a precision machine tool such as a robot. hard. (II) Since the work is done manually, the work cannot be made efficient, and it takes time and effort to make adjustments during measurement, resulting in high cost. Further, if there is a change in the type of the reduction gear or the reduction ratio, such troubles are further increased. (III) For the same reason, measurement cannot be automated, so
It is difficult to achieve automation of the entire system. As described above, the conventional example has problems in improving the measurement accuracy, easiness of measurement, and automation. Therefore, according to the present invention, a first counter for decreasing a first count value corresponding to a reduction ratio every predetermined pulse in synchronization with an input side rotation speed and a second counter value for every predetermined pulse. Is provided with a second counter that decreases in synchronization with the rotation speed on the output side, and indicates the angular error by the count value of the second counter when the count value of the first counter reaches a predetermined value. An object of the present invention is to provide a low-cost angle error measuring device capable of accurately and automatically measuring an angle error by detecting the angle error as a thing and easily measuring the angle error of various speed reducers. (Means for Solving Problems) In order to achieve the above object, the angle error measuring device according to the present invention is
An angular error between an input-side rotation speed input to a speed reducer that reduces the input-side rotation speed at a predetermined reduction ratio and transmits it to the output side, and an output-side rotation speed output from the speed reducer. An angle error measuring device for measuring the rotational speed of the input side as a predetermined pulse, a second rotational speed detection means for extracting the rotational speed of the output side as a predetermined pulse, and A first count value corresponding to the speed reduction ratio, and the first count value is decreased every predetermined pulse in synchronization with the rotation speed of the input side.
And a second counter that has a second count value different from the first count value and that decreases the second count value every predetermined pulse in synchronization with the rotation speed of the output side. Error detecting means for detecting the count value of the second counter when the count value of the first counter reaches a predetermined value as indicating the angular error. (Operation) In the present invention, the first counter that has the first count value corresponding to the reduction ratio and that decreases in synchronization with the rotation speed of the input side at every predetermined pulse is different from the first counter value. And a second counter that has a second count value and that decreases in synchronization with the rotation speed on the output side at every predetermined pulse,
The angle error is detected based on the count value of the second counter when the count value of the first counter reaches a predetermined value. Therefore, the angle error is accurately and automatically measured. (Example) Hereinafter, the present invention will be described with reference to the drawings. 1 to 8 show one embodiment of the present invention, and this embodiment is an example in which the present invention is applied to a speed reducer for decelerating an AC servomotor. First, the configuration will be described. In FIG. 1, 1 is a reduction ratio i
2 is an angle error measuring device. The speed reducer 1 is connected to the AC servo motor 4 via the input shaft 3,
The servomotor 4 rotates by the output of the AC servomotor drive amplifier 5 to drive the speed reducer 1. AC servo motor 4
An optical input encoder 6 is mounted to detect the rotation angle θin of the AC servo motor 4. The input encoder 6 converts the rotation speed of the AC servo motor 4 into a predetermined pulse and outputs the output pulse number Pin. Is output to the phase discriminating circuit 8 via the interface isolator 7 described later, and is also output to the AC servo motor drive amplifier 5. Therefore, the output pulse number Pin from the input encoder 6 is fed back to the AC servo motor drive amplifier 5, and the rotation speed of the AC servo motor 4 is feedback-controlled so as to be a predetermined constant value. In this embodiment, an AC servo motor is used as a motor for driving the speed reducer 1. However, the present invention is not limited to this, and for example, a DC servo motor or an induction motor may be used. Needless to say.
The output side of the reduction gear 1 is an optical output encoder (for example, NICON US
R) 11 is connected to the output shaft 9, and the output shaft 9 optically picks up the rotation speed decelerated by the speed reducer 1 and converts it into a predetermined pulse, which is divided by a divider (eg, NICON UC101) 12 and The output pulse number Pout is output to the phase determination circuit 14 via the interface isolator 13. The input encoder 6, the output encoder 11 and the divider 12 are pulse detection circuits (first rotation speed detection means,
The second rotation speed detecting means) 15 is configured. The interface isolators 7 and 13 are the input encoder 6
And an isolator for electrically protecting the internal circuit of the angle error measuring device when high voltage, high noise, etc. are superimposed on the pulse signal detected by the output encoder 11, or when an abnormality occurs in the encoder. There are pulse transformers and photocouplers, for example. As shown in FIG. 2, the optical encoders 6 and 11 for detecting the rotation angle output pulse waveforms of phase A and phase B having a phase of 90 ° with each other, and the rotation direction of the AC servomotor 4 or the output shaft 9 Fig. 3 shows the case of right rotation (CW rotation) and Fig. 4 shows the case of left rotation (CCW rotation). The rising edge of either phase A or phase B pulse comes first. Can be determined by. Therefore, as shown in FIG. 5, the rotation angle can be calculated by extracting the pulse signal in synchronization with the rising edges of the A-phase and B-phase pulses and counting the number of pulses of this pulse signal. However, the detection method shown in FIG. 5 causes problems in the following cases.
That is, even if the AC servomotor 4 or the output shaft 9 or the like makes a reciprocating rotation or a right / left rotation between the portions shown by the broken line in FIG. 6 for some reason, the output waveform as shown in FIG. 7 is obtained. Therefore, in this case, a pulse is output even if only left-right rotation is caused by vibration or the like, and it is considered that a certain rotation has been performed. Therefore, in this embodiment, in order to avoid the above problems, the rotation angle is calculated by discriminating all changes in the rising and falling edges of the A phase and the B phase. As a result, the A phase and the B phase are each multiplied by 4. In addition to the output of the A-phase and B-phase pulse waveforms from the input encoder 6, a pulse called a Z-phase is generated every time the input encoder 6 makes one rotation in order to show that the input encoder 6 has made one rotation. Output. The Z-phase pulse may be generated by forming a new slit in the input encoder 6, but one pulse having a pulse width different from the pulse widths of the A-phase and the B-phase is formed in advance. You may make it discriminate | determine Z phase by detecting the difference of a pulse width. Returning to FIG. 1 again, the phase discrimination circuits 8 and 14 discriminate the rotation direction from the A phase and B phase pulse signals input via the isolators 7 and 13, and the pulse signals as shown in FIG. The interface isolator 7, the phase discriminating circuit 8 and the interface isolator 13 constitute an encoder output signal processing circuit (first rotation speed detecting means, second rotation speed detecting means) 16 as a whole. ing. The input-side pulse signal extracted by the phase determination circuit 8 is input to the Pin counter 21, and the Pin counter 21 is composed of a down counter having a count value equal to the speed reduction ratio i of the speed reducer 1. Therefore, when the pin counter 21 receives the pulse signal from the phase determination circuit 8 in synchronization with the rotation of the AC servomotor 4,
As shown in FIG. 8 (a), the count value i is down-counted by one, and the Pin counter 2
The count value of 1

When [0] is reached, i is loaded again in the data. The reduction ratio i of the speed reducer 1 is 12
There are many things around 0. On the other hand, the pulse signal on the output side extracted by the phase determination circuit 14 is input to the Pout counter A22 and the Pout counter B23, respectively.
The Pout counter B23 is a down counter having the same count value (162 in this embodiment). That is, the count value 162 used for the Pout counter A22 and the Pout counter B corresponds to the pulse of the output-side out dot encoder 11 with respect to one pulse of the input encoder 6 attached to the input side.
The number of output pulses per [arcsec] is 8000 p / rev (in the present embodiment, in order to improve the measurement accuracy, A-phase and B-phase pulse signals with a 90 ° phase shift as described above are used. When the phase pulse signal is detected, for example, if the number is 2000p / rev, 2000p / rev is multiplied by 4 to obtain 8000
p / rev can be obtained and the resolution can be increased four times), and the output pulse number of the output encoder 11 is 1296000p / rev (similarly, 324000p / rev is multiplied by 4), The number of pulses on the output side for one pulse on the input side is 1296000/8000 = 162. When the pulse signal is input from the phase determination circuit 14 in synchronization with the output of the speed reducer 1, the Pout counter A22 and the Pout counter B23 count down one by one from the count value 162 as shown in FIGS. 8 (b) and 8 (c). For example Pout
The count value of counter A22 is

When it becomes [0], the count value 162 is loaded into the Pout count B23, and the Pout counter B2
3 starts counting down. At this time, the count value of Pout counter B23 of Pout counter A22

Counting is continued until it becomes [0], and the count value of Pout counter B23 is

When it becomes [0], the count value 162 is again displayed in the Pout counter A22.
Is loaded. In this way, the Pout counter on the output side is 2
They are used individually and counting Pout in parallel. Here, Pin counter 21, Puot counter A22, Pout counter B2
A start signal and a reset signal are input to the 3 as control signals from a system control unit 52, which will be described later, and each counter starts counting by the start signal or the reset signal. Pin counter 2 above
1, Pout counter A22 and Pout counter B23 form a rotation angle calculation unit 24. The count values from the Pout counter A22 and Pout counter B23 are input to the data selector 31, and the count signal from the Pin counter 21 is input to the data selector 31 by the delay circuit 3
It is input as a select signal via 2. In the data selector 31, the count value i of the Pin counter 21 is

Data is read alternately from the Pout counter A22 and the Pout counter B23 every time it becomes [0]. The count value of the Pout counter A22 or Pout counter B23 at this time is shown in FIG.
It is the angle transmission error θer shown in (c). Since θer is a cumulative error, two Pout counters are used in this embodiment,
Performs Pout counting in parallel. As a result, the count values of the Pout counter A22 and Pout counter B23 are reloaded at an appropriate count value, so that it is possible to use a general-purpose counter with a relatively small count number and reduce costs. Can be planned. Delay circuit 32
Is the count value of Pin counter 21

When it becomes [0], P
To ensure that the count value θer of the out counter A22 or Pout counter B23 is read by the data selector 31, a predetermined delay is provided before the end of reading the data. The θer value calculated by the data selector 31 is latched
It is input to 33 and the θer value is latched by using the count signal from the Pin counter 21 as a latch enable signal. The data selector 31, the delay circuit 32, and the latch 33 form a θer arithmetic circuit 34. The θer value of the latch 33 is input to the digital display 41 and the D / A converter 42. The digital display 41 is composed of, for example, a numerical display element, digitally displays the θer value, and also performs D / A conversion. The device 42 converts the θer value into an analog signal θer and outputs the analog signal θer to the fast Fourier transform (FFT) circuit 43.
The fast Fourier transform circuit 43 performs a fast Fourier transform on the waveform of θer input as an analog signal for each predetermined clock pulse from the sampling glock generation circuit 44 to perform frequency analysis, and outputs the result to the plotter 45. The digital display 41, the D / A converter 42, the fast Fourier transform circuit 43, the sampling clock generation circuit 44, and the plotter described above.
45 constitutes the θer value output unit 46. On the other hand, the Z-phase pulse detected by the Pin counter 21 is input to the motor rotation number determination circuit 51, and the motor rotation number can be detected by counting the Z-phase pulse. Here, if a predetermined number of pulses is set in advance, the angular error can be detected with proper rotation. When the detection of the angle error is completed, the system control unit
Detect reset signal at 52. The system control unit 52 receives the reset signal from the motor rotation number determination circuit 51, controls the angle error measuring device, and
A control command for driving the servo motor 4 is output to the AC servo motor drive amplifier 5. Next, the operation will be described. First, the input encoder 6 converts the rotation speed of the AC servo motor 4 into predetermined pulses Pin of A phase, B phase, and Z phase, and the phase determination circuit 8 uses the phase discrimination circuit 8 to determine the AC servo motor based on the A phase and B phase pulses. A pulse signal corresponding to the rotation angle of 4 is taken out. Further, as shown in FIG. 8 (a), the Pin counter 21 is loaded with a count value equal to the speed reduction ratio i of the speed reducer 1 as data in the initial state. Each pulse signal taken out is counted down. On the other hand, the rotation speed on the output side of the speed reducer 1 is converted into a predetermined pulse Pout of A phase and B phase by the output encoder 11, and the output side of the speed reducer 1 is output on the output side of the speed reducer 1 by the phase discrimination circuit 14 as in the case of the input side. The pulse signal corresponding to the rotation speed of is extracted. Furthermore, 162 is loaded as data to the count value of the Pout counter A22 in the initial state, and this count value 1
Down counting is performed for each pulse signal extracted by the phase determination circuit 14 from 62, and the count value is

When it becomes [0], 162 is loaded as data to the count value of the Pout counter B23 as shown in FIG. 8C (whether the Pout counter A22 is the count value of the Pout counter B23 or not).

Continue counting down until it reaches [0]). And this count value
The count value of the Pout counter B23 is decreased by counting down each pulse signal extracted by the phase determination circuit 14 from 162.

When it becomes [0], the data 162 is loaded again in the Pout counter A22. The above operation is repeated. Then, the count value of the Pin counter 21 is

When it becomes [0], the data selector 31 causes the Pout counter A22 or Pou
t Read the data of counter B23. This data becomes the angle transmission error θer. That is, assuming that the speed reducer 1 does not have the angle transmission error θer, if the down count is performed from the Pin counter 21 in synchronization with the input side rotation speed of the speed reducer 1, the count value counts the gear ratio i. By the way, the count values of Pout counter A22 and Pout counter B23, which are down-counting in synchronization with the rotation speed on the output side, are also

Should be [0],

If it does not become [0], the difference becomes θer. Therefore, in addition to making it possible to automate the measurement of θer, it is possible to dramatically improve the measurement accuracy and improve work efficiency. In particular,
It is suitable to apply the angle error measuring device of the present invention when measuring the angle error of a speed reducer used in a precision machine tool such as a robot. (Effect) According to the present invention, the first counter and the second count value that decrease the first count value corresponding to the reduction ratio in synchronization with the rotation speed of the input side every predetermined pulse and the second count value every predetermined pulse. A second counter that decreases in synchronization with the rotational speed on the output side, and indicates the angular error by the count value of the second counter when the count value of the first counter reaches a predetermined value Therefore, the angle error can be accurately and automatically measured, and the angle error of various speed reducers can be easily measured.

[Brief description of drawings]

1 to 8 are diagrams showing an embodiment of an angle error measuring apparatus according to the present invention, FIG. 1 is an overall configuration diagram thereof, FIG. 2 is a waveform diagram showing an output waveform of the encoder, and FIG. Is a waveform diagram showing the output waveform of the encoder when the rotation direction is right rotation, FIG. 4 is a waveform diagram showing the output waveform of the encoder when the rotation direction is left rotation, and FIG. 5 is the output waveform of the encoder 6 is a waveform diagram showing a pulse waveform in the case of reciprocating rotation, FIG. 7 is a waveform diagram showing an output waveform of the encoder in the case of reciprocating rotation, and FIG.
It is a figure which shows the count value of n counter, Pout counter A, and Pout counter B. 1 ... Reducer, 2 ... Angle error measuring device, 21 ... Pin counter (first counter), 22 ... Pout counter A (second counter), 23 ... Pout counter B (second counter) ), 15 ... Pulse detection circuit (first rotation speed detection means, second rotation speed detection means)
Rotational speed detection means), 16 ... Encoder output signal processing (first rotational speed detection means, second rotational speed detection means), 34 ... θer arithmetic circuit (error detection means).

Claims (1)

[Claims] 1. An input-side rotational speed input to a speed reducer that reduces the input-side rotational speed at a predetermined reduction ratio and transmits the output-side rotational speed, and an output-side rotational speed output from the speed reducer. In an angle error measuring device for measuring an angular error between the two, a first rotation speed detecting means for extracting the rotation speed on the input side as a predetermined pulse, and a second rotation speed for extracting the rotation speed on the output side as a predetermined pulse. A detecting means; a first counter having a first count value corresponding to the speed reduction ratio, which decreases the first count value at every predetermined pulse in synchronization with the rotation speed of the input side; A second counter having a second count value different from the count value of 1 and decreasing the second count value at every predetermined pulse in synchronization with the rotation speed of the output side; and the first counter. When the count value of Angle error measuring device comprising an error detecting means, further comprising a detecting the count value of the counter second as an indication of the angular error of.