JP5037437B2 - Encoder with internal information output function - Google Patents

Description

  The present invention relates to an encoder that detects the position and speed of a servo motor that drives a shaft of, for example, a machine tool or an industrial robot. More specifically, the encoder itself or a motor that detects the position or speed by the encoder has an abnormality. The present invention relates to an encoder that can provide information that contributes to an analysis of the cause of an abnormality when it occurs.

  Encoders for detecting the position and speed of servo motors that drive the axes of machine tools and industrial robots are widely used. Anomalies may occur in the encoder and the servo motor due to various internal factors or external factors. Therefore, self-diagnosis is performed inside the encoder for the presence or absence of these abnormalities, and when a self-diagnosis result indicating any abnormality is obtained, it is transmitted as alarm information to the numerical controller.

  As shown in FIG. 9, the numerical controller 1 that controls the servo motor 2 communicates with a (prior art) encoder 3 ′ built in the servo motor 2 via communication cables 8, 9, A servo loop is formed by speed feedback information, and the servo motor 2 is controlled. The encoder 3 ′ includes a plurality of abnormality detection circuits (not shown) therein, and notifies the numerical control device 1 as alarm information when the encoder 3 ′ itself detects an abnormality.

  FIG. 10 shows an example of a communication signal transmitted as serial data by the encoder 3 ′ in response to the data request signal from the numerical controller 1 in the configuration shown in FIG. 9. When the encoder 3 ′ detects an abnormality, the encoder 3 ′ transmits a portion indicating the content (a signal indicating the presence or absence of the abnormality) as H. As shown in FIG. 10, the data transmitted from the encoder 3 ′ to the numerical controller 1 is alarm information and position information.

  When the numerical controller 1 receives an alarm indicating an abnormality of the encoder 3 ′, the numerical controller 1 displays the content of the alarm. The operator confirms the contents, and usually the power is first turned off and then turned on to try to recover. If the recovery operation is successful, the operation of the machine is continued, and if the alarm is continuously generated or if the alarm reoccurs, measures such as replacement of the encoder 3 'are performed.

  As a technique for identifying an abnormality inside the encoder, Patent Document 1 discloses a technique for storing internal information at the time of occurrence of an alarm and reading it later by an external device to identify the cause of the occurrence of the alarm. .

JP 2005-221258 A

  In recent years, encoders have been improved in resolution and compatible with high-speed rotation, and the conventional A / B output method has been changed to a method of transferring data by serial communication independent of the resolution and the rotation speed. The data transferred by serial communication includes alarm information indicating an abnormality detected in the encoder in addition to the position or speed information. Compared to the conventional A / B phase output method, the information transmitted from the encoder The amount is increasing dramatically.

  The main information transmitted by the encoder is position information or speed information, and the communication cycle is limited to be short for the purpose of improving the controllability of the servo motor, and the amount of data transmitted in one communication is limited. In particular, since the amount of alarm information is limited to a necessary minimum, it may be difficult to determine whether there is an abnormality in the encoder or to specify where the abnormality is in the encoder only from the alarm information.

  In the technique disclosed in Patent Document 1 described in the background art, an alarmed encoder is replaced, and the cause of the alarm is investigated after the encoder is replaced. This technology is very effective in investigating the cause of an alarm after replacing the encoder. However, when the alarm occurs, the cause of the abnormality cannot be accurately identified, and it is applied in response to the alarm on the spot where the encoder is used. There is a problem that treatment cannot always be performed appropriately.

  The encoder detects an abnormality and sends an alarm to the control device. When receiving the alarm from the encoder, the control device stops the control of the machine to be controlled. The position information or speed information after the control is stopped is not necessarily related to the control (not necessarily used for the control).

  Therefore, the present invention detects the abnormality and sends out the alarm information, then switches the data content transmitted from the encoder, transmits the internal information necessary for specifying the abnormal part, and determines whether the encoder is abnormal. It is an object of the present invention to provide an encoder capable of accurately determining a judgment and specifying an abnormality in an encoder.

  The invention according to claim 1 of the present application is an encoder that is connected to a control device and detects and outputs at least one of position information and speed information of a motor controlled by the control device or a driving body driven by the motor. When an abnormality inside the encoder is detected, alarm information indicating the abnormality is transmitted, and instead of the position information or the speed information, the internal information of the encoder at the time point when the abnormality is detected and at least one time point before the predetermined time An encoder having an internal information output function characterized by switching and transmitting data.

  In the invention according to claim 2, in the internal information, the encoder detects (1) at least one of a time point at which a signal indicating the presence of the abnormality is generated and a time point a predetermined time before the time point. (2) Speed information detected by the encoder at at least one of a time point at which a signal indicating the presence of the abnormality is generated and a time point a predetermined time before the time point, and (3) the abnormality information Temperature information of the encoder at a time point at which a signal indicating the presence is generated and a time point a predetermined time before the time point; (4) a time point at which the signal indicating the presence of the abnormality is generated and a predetermined value from the time point The temperature information of the servo motor at at least one time point before the time, and (5) the time point when the signal indicating the presence of the abnormality is generated and the predetermined time from the time point In at least one time prior to the time, an encoder having an internal information output function according to claim 1, characterized in that it contains at least one of the grounds for determining that the abnormality information, the.

  The invention according to claim 3 includes abnormality signal generation means for generating a signal indicating the presence or absence of abnormality for each of a plurality of abnormality check items related to at least one of the encoder and the motor, and the internal information includes the plurality of the plurality of abnormality check items. Presence / absence of abnormality in each of the plurality of abnormality check items at the time when a signal indicating the presence of abnormality is generated by the abnormality signal generating means or at a predetermined time before the time for at least one of the abnormality check items The encoder having the internal information output function according to claim 1, wherein information of a signal representing the signal is included.

  According to a fourth aspect of the present invention, there is provided an integrated total movement amount calculating means for measuring an integrated total movement amount of the encoder, and the internal information includes a time point at which a signal indicating the presence of the abnormality is generated or a predetermined value from the time point 4. At least one of the information of the integrated total movement amount measured by the integrated total movement amount calculation means at a time point before time is included. This is an encoder having an internal information output function.

  The invention according to claim 5 is provided with an integrated operation time calculation means for measuring an integrated operation time of the encoder, and the internal information includes a time point at which a signal indicating the presence of the abnormality is generated or a predetermined time before the time point. The internal information output according to any one of claims 1 to 3, wherein at least one of the pieces of information on the accumulated operation time measured by the accumulated operation time calculation means at the time is included. This is an encoder having a function.

  The invention according to claim 6 is characterized in that switching to transmission of the internal information is performed based on a pattern of a data request signal from a control device. This is an encoder having an internal information output function.

  According to the present invention, the encoder detects an abnormality, transmits alarm information, switches the data content transmitted from the encoder, and transmits internal information (including internal information before the time when the abnormality occurs) necessary to identify the abnormal part. Thus, it is possible to provide an encoder having an internal information output function that allows an operator to easily determine whether there is an abnormality in the encoder and to specify where the abnormality is inside the encoder.

  Also, when an engineer investigates an encoder that has been alarmed and replaced, the failure location and cause of occurrence can be accurately estimated by internal information even if the items to be investigated in detail or narrowing down or the alarm is not reproduced It is possible.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram for explaining that an encoder having an internal information output function according to the present invention switches output information to internal information and transmits it. Components having the same or similar functions in FIGS. 1 and 9 are given the same reference numerals. The numerical controller 1 receives position information / velocity information feedback information from the encoder 3 and position information feedback information from a separate encoder (for example, a linear scale), and outputs a signal for controlling the drive of the servo motor 2 as power. Output to the servo motor 2 via the line 7.

  When the encoder 3 detects an abnormality, it notifies the numerical control device 1 as alarm information. When the numerical control device 1 receives an alarm indicating an abnormality of the encoder 3, the numerical control device 1 performs control to stop the operation of the table 4, which is a machine, and displays the contents of the alarm.

  The encoder 3 detects an abnormality and transmits alarm information to the numerical control device 1, and after a predetermined time, switches from position / velocity information to internal information and transmits it to the numerical control device 1. The numerical control device 1 reads the information and performs at least one of display (1b) and storage on the display device of the numerical control device 1. At this time, the table 4 is in a stopped state, and the data transmitted by the encoder 3 is not used for controlling the motor that drives the machine, so there is no particular limitation on the transmission time or the amount of data. It is possible to send internal information.

  Then, the operator determines the cause of the abnormality from the contents of the alarm and the internal information of the encoder. For example, when an overheat alarm occurs, it is determined whether or not the overheat alarm is normally detected from temperature information which is one of internal information, and whether there is no abnormality such as disconnection in the temperature detection signal line. Further, when the alarm reoccurs, the numerical control device 1 determines whether or not there is an abnormality by comparing it with the memory of the past occurrence. For example, if the position where the alarm is generated is the same as in the past, it is determined that there is an abnormality depending on the position, and a measure such as cleaning the portion corresponding to the position of the encoder 3 is performed.

  In this way, the encoder 3 is characterized by transmitting internal information for accurately identifying a failure location and handling when an abnormality is detected. Furthermore, since internal information can be used when engineers investigate encoders that have been alarmed and replaced, it is easy to narrow down detailed investigation items, and even if alarms are not reproduced, faults and abnormalities occur. The cause can be estimated.

  FIG. 2 is a diagram for explaining a first embodiment of an encoder having an internal information output function according to the present invention. The encoder 3 is attached to the servo motor 2 and changes with the rotation of the output shaft of the servo motor (not shown) (position signal, single rotation signal, magnetic pole signal), and the encoder temperature signal changes with the encoder temperature. Also, the motor temperature signal that changes depending on the temperature of the servo motor is detected.

  Internal signals (position signal, single rotation signal, magnetic pole signal, encoder temperature signal, motor temperature signal) of the encoder are processed by the signal processing unit, and position data, magnetic pole data, and temperature data are created. These data are converted into serial data by a serial data transmitter / receiver in accordance with a data request signal from the numerical controller, and transmitted to the numerical controller via the transceiver.

  The alarm detection unit monitors the voltage level (amplitude, offset) of the signal, the phase difference relationship between the signals, etc., and when an abnormal state is determined, at least one bit in the alarm information assigned in the serial data is The state is changed from “L” to “H” to notify the control device of the abnormality.

  Register 1, register 2, and register 3 constitute a shift register, which stores each data and alarm information as internal data, and simultaneously performs the next operation by a data update timing signal based on a clock. That is, the register 1 stores internal data, the register 2 stores data of the register 1, and the register 3 stores data of the register 2.

  In this configuration, by stopping the data update timing signal when an abnormality is detected by the alarm detection unit, internal information at the time when the abnormality is detected and a predetermined time before the abnormality detection is retained, and then the serial data transmission / reception control unit stores the data internally. Switch to information and send. In the example described above, the register has three stages of 1 to 3, but the predetermined time can be arbitrarily changed by increasing or decreasing the number of stages of the register.

  Therefore, the encoder 3 can transmit internal information from a past time point that is a predetermined time later than the time point when the abnormality is detected, an abnormality occurrence time point, and internal information after the abnormality occurrence point to the numerical control device 1. As described with reference to FIG. 1, the numerical control device 1 reads the internal information and performs at least one of display (1b) and storage on the display device.

  Here, the encoder internal signals (position signal, single rotation signal, magnetic pole signal, encoder temperature signal, motor temperature signal) are processed by the signal processing unit to supplement the creation of position data, magnetic pole data, and temperature data. I will explain.

  The position signal is generated by a circuit block (not shown) in which an AD converter or the like is combined with a position data encoder signal amplifier. The position signal generated by the block is a circuit configured as a position data calculation circuit in the signal processing unit, and is input to a circuit that calculates a position (rotational position or linear position) based on a known calculation process. To do. The position information calculated by the position data calculation circuit is sequentially input to the transceiver via the serial data transmission / reception unit, and is transmitted from there to the numerical controller 1.

  The numerical controller 1 performs feedback control based on position information and speed information. When speed information is required, the position data calculation circuit can be used as the “position data and speed data calculation circuit” to create speed data in the encoder, or based on the position data in the numerical controller 1. It can also be calculated.

  The encoder signal amplifier for position encoders amplifies signals of various phases (A phase, B phase, Z phase, etc.) generated according to the rotation of the optical code plate (in the case of a rotary encoder) or linear movement (in the case of a linear encoder) An analog signal circuit.

  In the case of a rotary encoder, one rotation signal is a reference signal (Z-phase signal) within one rotation, and the magnetic pole signal is a signal that indicates the position (electrical angle) of the servo motor shaft with respect to the magnetic pole. A signal representing the position of the motor shaft is input to the signal processing circuit, and the calculation result is transmitted to the numerical controller 1 via the serial data transmitting / receiving unit and the transceiver. The one rotation signal and the magnetic pole signal are used inside the encoder 3 for calculation of an integrated total movement amount such as an integrated total rotational speed described later.

  The encoder temperature signal is an output of an encoder temperature detection element that senses the temperature of the encoder, and the motor temperature signal is an output of a servo motor temperature detection element that senses the temperature of the servo motor 2. These temperature signals are input to a temperature detection circuit configured in the signal processing unit, the temperature of the encoder 3 and the temperature of the servo motor 2 are detected based on the input signal, and the detection result is input to the alarm detection unit. In addition to these temperature-related signals, the alarm detection unit receives the position detection circuit, a single rotation signal, and the output of the magnetic pole detection circuit.

  The alarm detection unit detects the presence / absence of an abnormality in one or more check items based on these input signals. Each check item corresponds to an alarm type (overheat alarm, position alarm, etc.), and the detection result of each check item is output as “1” (abnormal) and “0” (no abnormality).

  When “1” is output, an alarm corresponding to the check item is sent to the numerical controller 1. Whether the detection result of each check item is “1” or “0” is determined by the presence or absence of abnormality of the check factor related to the check item. Usually, there are two or more check factors related to one check item, and if any one of them is abnormal, the output of the check item is “1” (abnormal). Specifically, a logical sum of signals representing the determination results of the respective check factors is sent to the numerical controller 1 via the serial data transmission / reception unit and the transceiver. If this logical sum is "1", an alarm is output.

  On the other hand, various internal information of the encoder 3 is stored in the registers 1, 2, and 3 at the data update timing. When the alarm is generated, the data update timing signal is stopped to retain the internal information at the time when the alarm is detected and the predetermined time before the alarm is detected, and then the serial data transmission / reception control unit switches the data to the internal information and sends it out. To do.

  The information stored in the registers 1, 2 and 3 is an alarm signal (a signal indicating the occurrence of the alarm itself) and internal information indicating the current state of the encoder 3 or the servo motor 2 to be inspected by the encoder 3. Yes, it is information that has the property of changing at least when the servo motor is operating. The internal information includes, for example, temperature information (information indicating the temperature of the encoder and the temperature of the servo motor detected by the temperature detection circuit), position information or speed information (position information or speed information calculated by the position data calculation circuit). ), Abnormality determination basis information (information that is the basis for determining that an abnormality has occurred, and that represents the state of the encoder, servo motor, encoder temperature detection element, and servo motor temperature detection element in a more raw form). These alarm signals and internal information are information obtained by an encoder which is a conventional technique, and a technique for collecting such information is a known technique (for example, see Patent Document 1).

  Next, a second embodiment of the present invention will be described. FIG. 3 is a second embodiment of the present invention capable of outputting information related to the lifetime of the encoder 3 as internal information. In the embodiment shown in FIG. 3, a circuit block capable of counting the total accumulated number of rotations, which is the total accumulated movement amount, is further provided in the first embodiment of the present invention described in FIG. This circuit block is provided with integrated total revolution number storage means for storing the accumulated total revolution number. With this configuration, it is possible to store the total number of rotations of the encoder at the time of occurrence of an abnormality. When the encoder 3 detects an abnormality, the integrated total rotational speed stored in the integrated total rotational speed storage means is written in the register 1 as one of internal information in response to a command from the alarm detection unit.

  Also, instead of (or in addition to) the circuit block capable of counting the total number of revolutions, the total total operating time for storing the total total operating time since the start of use of the encoder as storage information when an abnormality occurs An integrated total operation time counting circuit having storage means is provided.

Note that the total accumulated revolutions and the accumulated total operating time stored in the accumulated total revolution number storage means and the accumulated total operating time storage means are the total accumulated revolutions and the accumulated total operating time at a predetermined time before the occurrence of the abnormality, It may be configured to include at least one of the total accumulated number of revolutions and the total accumulated operating time at the time of occurrence of the abnormality.
These embodiments can provide material that is useful in determining if an abnormality occurs is related to the life of the encoder.

Next, an example of transmission of internal information transmitted from the encoder 3 shown in FIG. 2 to the numerical controller 1 will be described.
FIG. 4 shows an example in which an encoder having an internal information output function according to the present invention transmits alarm information and automatically switches to output internal information after a predetermined time. When detecting an abnormality, the encoder 3 transmits the corresponding portion of the alarm information (in other words, a signal indicating the presence or absence of abnormality) to the numerical control apparatus 1 as H. Then, it automatically switches to outputting internal information after a certain time.

  FIG. 5 shows an example in which an encoder having an internal information output function according to the present invention transmits alarm information and automatically switches to output of internal information after a certain time and transmits a plurality of internal information at once. . When the encoder 3 detects an abnormality, the encoder 3 transmits the corresponding portion of the alarm information (a signal indicating the presence or absence of abnormality) to the numerical control apparatus 1 as H. And it switches so that internal information may be output automatically after a fixed time.

  FIG. 6 shows an example in which an encoder having an internal information output function according to the present invention transmits alarm information and automatically switches to output of internal information after a predetermined time and sequentially transmits a plurality of internal information. When the encoder 3 detects an abnormality, the encoder 3 transmits the corresponding portion of the alarm information (a signal indicating the presence or absence of abnormality) to the numerical control apparatus 1 as H. And it switches so that internal information may be output automatically after a fixed time.

FIG. 7 shows an example in which an encoder having an internal information output function according to the present invention transmits internal information according to a pattern of an internal information request signal from a numerical controller. In this embodiment, the pattern of the internal information request signal from the control device is changed to request that the encoder transmit the internal information corresponding to the pattern.
When detecting an abnormality, the encoder 3 transmits the corresponding portion of the alarm information (a signal indicating the presence or absence of abnormality) as H. When the numerical controller 1 recognizes the alarm, it changes the pattern of the data request signal and requests the encoder 3 to output internal information.

  FIG. 8 shows an example in which the encoder transmits alarm information and automatically switches to transmitting only internal information after a predetermined time. In the transmission example described above, the encoder continues to transmit alarm information together with internal information. Since the alarm information does not change, if an abnormality occurs and the alarm information is transmitted to the numerical control device for a certain period of time, the numerical control device can recognize that an abnormality has occurred in the encoder (however, the numerical control device Must have software or hardware that recognizes only internal information). Therefore, the alarm information need not be continuously transmitted to the numerical controller. In this way, more internal information can be transmitted to the numerical control device.

It is a figure explaining that the encoder which has the internal information output function which is this invention switches the information to output to internal information, and transmits. It is a figure explaining 1st Embodiment of the encoder which has an internal information output function which is this invention. It is a figure explaining 2nd Embodiment of the encoder which has an internal information output function which is this invention. This is an example in which an encoder having an internal information output function according to the present invention automatically switches to output internal information after transmitting alarm information for a certain time. This is an example in which an encoder having an internal information output function according to the present invention transmits alarm information and automatically switches to output of internal information after a predetermined time and transmits a plurality of internal information at once. The encoder having an internal information output function according to the present invention is an embodiment of the present invention in which a plurality of internal information is transmitted in order by automatically switching to output of internal information after a certain time after transmitting alarm information. . This is an example in which an encoder having an internal information output function according to the present invention transmits internal information according to a pattern of an internal information request signal from a numerical controller. This is an example in which an encoder having an internal information output function according to the present invention automatically transmits only alarm information after transmitting alarm information for a predetermined time. It is an example which notifies a numerical control apparatus as alarm information which is a prior art. This is an example in which a part indicating the presence or absence of abnormality is carried in alarm information, which is a conventional technique.

Explanation of symbols

1 Numerical controller
2 Servo motor 3 Encoder 3 '(Prior art) encoder 4 Table 5 Ball screw 6 Separate encoder 7 Power line 8 Speed feedback communication cable 9 Position feedback communication cable

Claims (6)

  In an encoder connected to a control device and detecting and outputting at least one of position information and speed information of a motor controlled by the control device or a driving body driven by the motor, when an abnormality inside the encoder is detected, The alarm information indicating the abnormality is transmitted, and the data is transmitted by switching to the internal information of the encoder at least one of the time point when the abnormality is detected and the time point before the predetermined time instead of the position information or the speed information. An encoder having an internal information output function. The internal information includes
(1) Position information detected by the encoder at a time point at which a signal indicating the presence of the abnormality is generated and a time point a predetermined time before the time point;
(2) Speed information detected by the encoder at a time point at which a signal indicating the presence of the abnormality is generated and a time point a predetermined time before the time point;
(3) Temperature information of the encoder at a time point at which a signal indicating the presence of the abnormality is generated and a time point a predetermined time before the time point;
(4) Temperature information of the servo motor at a time point at which a signal indicating the presence of the abnormality is generated and a time point a predetermined time before the time point; and
(5) At least one of the information that is the basis for determining that there is an abnormality at the time when the signal indicating the presence of the abnormality is generated and at least one time before the predetermined time is included. The encoder having the internal information output function according to claim 1. An abnormality signal generating means for generating a signal indicating the presence or absence of abnormality for each of a plurality of abnormality check items related to at least one of the encoder and the motor;
The internal information includes the plurality of abnormalities at a time when a signal indicating the presence of an abnormality for at least one of the plurality of abnormality check items is generated by the abnormal signal generation unit or a predetermined time before the time. The encoder having the internal information output function according to any one of claims 1 and 2, wherein each of the check items includes signal information indicating presence / absence of abnormality. An integrated total movement amount calculating means for measuring an integrated total movement amount of the encoder;
The internal information includes at least one of the information of the integrated total movement amount measured by the integrated total movement amount calculating means at the time when the signal indicating the presence of the abnormality is generated or at a predetermined time before the time point. The encoder having an internal information output function according to claim 1, wherein one encoder is included. An integrated operating time calculating means for measuring the integrated operating time of the encoder;
The internal information includes at least one of the information on the accumulated operation time measured by the accumulated operation time calculation unit at the time when the signal indicating the presence of the abnormality is generated or at a time before the time. The encoder having the internal information output function according to claim 1, wherein the encoder has an internal information output function.   6. The encoder having an internal information output function according to claim 1, wherein switching to transmission of the internal information is performed based on a pattern of a data request signal from a control device.

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