JPH10275006A - Industrial robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the industrial robot which can decrease the number of signal lines needed for data communication, improve the degree of freedom of laying of the signal lines, and prevent the reliability of data from decreasing. SOLUTION: The industrial robot having a three-axial servo system provided with 1st-axis to 3rd axis motor drivers 7-1 to 7-3 corresponding to 1st-axis to 3rd-axis position detectors 4-1 to 4-3 has all the position detectors and motor drivers connected in a daisy chain by a serial communication line 5 as a signal line of one system. Data are communicated between pairs of the position detectors and motor drivers with packeted request signals and position data signals including address specification bits of the position detectors to acquire position data and perform an error process, etc., while judging whether or not various errors occur.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an industrial robot for performing data communication on the operating state of a movable section by serial communication.

[0002]

2. Description of the Related Art In an industrial robot having a servo system including a servomotor, a position detector and a motor driver, there is known an industrial robot which transmits position data from the position detector to the motor driver by high-speed serial communication. I have. In such an industrial robot, the movable portion operates by the driving force of the servomotor, and the amount of operation (rotation angle position) is detected by the position detector as position data including analog data and pulse data. Then, the position data is converted into digital data and transmitted to the motor driver in the control device by dedicated high-speed serial communication.

In a conventional industrial robot, when transmitting position data by serial communication, it is necessary for a position detector and a motor driver to perform one-to-one communication. A signal line (serial communication line) for transmitting position data is provided in accordance with the number of sets of motor drivers and motor drivers. Then, each set of the position detector and the motor driver is operated asynchronously, and in each set, a position data acquisition request from the motor driver, a position data transmission from the position detector, etc. are performed via the respective signal lines. Had been

According to such position data transmission by serial communication, the number of signal lines can be reduced as compared with a case where position data is transmitted by analog communication or pulse data as parallel data, thereby simplifying wiring. Can be planned. This is also effective in improving data reliability.

[0005]

However, in the above-mentioned conventional industrial robot, it is necessary to provide signal lines according to the number of sets of position detectors and motor drivers, that is, the number of axes. For this reason, in a multi-axis control device such as an industrial robot, the number of signal lines increases in accordance with the number of axes, the degree of freedom of signal line routing decreases, and twisting, bending, and vibration of each signal line occur. In addition, there has been a problem that the reliability of data is reduced due to contact or the like.

Normally, the signal line is connected to a cable connecting the control device side and the robot side and a position detector in the robot, with emphasis on ease of use, ease of assembly, maintainability, portability, and the like. It is composed of an internal wiring cable for connecting to the connection part of the cable, and a connector provided at each connection part of these cables. Therefore, the increase in the number of signal lines as described above has also caused problems such as an increase in man-hours required for assembling and wiring the cables and connectors, and ensuring reliability in connector connection.

[0007] The present invention has been made in view of such circumstances, and it is possible to reduce the number of signal lines required for data communication in an industrial robot, and to improve the degree of freedom in routing signal lines. In addition to reducing the reliability of data due to twisting or bending of the signal line, the number of steps required to provide the signal line can be reduced, and the reliability of the connection portion can be easily reduced. It is an object of the present invention to provide an industrial robot that can be ensured in an industrial robot.

[0008]

According to the present invention, there is provided an industrial robot having a plurality of movable parts, wherein a control device instructs an operation of each of the plurality of movable parts. A single signal line provided between the plurality of movable units, a plurality of detection means provided corresponding to each of the plurality of movable units, for detecting the operating state of the movable unit, and the plurality of A plurality of drive control units are provided corresponding to each of the detection units and control the driving of the movable unit, and each of the plurality of the detection units receives an instruction signal from the control device via the signal line. Receiving, when the instruction signal specifies itself and requests a detection result, outputs a detection result signal with data specifying itself to the signal line,
The plurality of drive control units each output the instruction signal to which the data specifying the detection unit corresponding to the drive control unit to the signal line, receive the detection result signal via the signal line, and perform the detection. It is characterized in that the detection result signal is obtained by selecting the detection result signal from the detection means corresponding to itself according to the data attached to the result signal.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION

<Configuration> (1) Overall Configuration An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram schematically showing an overall configuration of an industrial robot according to one embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a robot main body, which has three axes (not shown) of a first axis, a second axis, and a third axis.
A movable part (not shown) corresponding to each axis operates to perform work on the workpiece. Here, for simplicity of explanation, an industrial robot equipped with a three-axis servo system in which the number of axes of the robot body 1 is three will be described as an example.

Reference numerals 2-1, 2-2, and 2-3 denote a first axis servo motor, a second axis servo motor, and a third axis servo motor corresponding to the first axis, the second axis, and the third axis, respectively. It is.
These servo motors are provided in the robot body 1, and the driving force generated at each output shaft is transmitted via a speed reducer, a belt, a link, a tool, and the like.
The movable part corresponding to each axis is operated. Motor power lines 3-1, 3-2, and 3-3 are connected to each servo motor, and power for generating a driving force is supplied through these connection lines.

Reference numerals 4-1, 4-2, and 4-3 denote a first axis servo motor 2-1, a second axis servo motor 2-2,
A first axis position detector, a second axis position detector, and a third axis position detector attached to the third axis servomotor 2-3.
These position detectors detect the rotation position and the number of rotations of the output shaft of the servomotor to which each is attached, and generate position data of each movable section based on the detection result. Then, the position data is output to the serial communication line 5 in the form of a serial signal and transmitted to the control device 6. The internal configuration of these position detectors will be described later in detail.

The serial communication line 5 is connected to the first axis position detector 4
-1, second axis position detector 4-2 and third axis position detector 4
-3, the first axis motor driver 7-1 in the control device 6,
This is a signal line connecting between the second axis motor driver 7-2 and the third axis motor driver 7-3. The serial communication line 5 connects the robot body 1 and the control device 6 with each other.
It is composed of two signal lines, and both ends are branched in the robot body 1 and the control device 6 and connected to each position detector and each motor driver. In this way, all the position detectors and the motor drivers are daisy-chain connected to the serial communication line 5, which is one signal line.

The control device 6 is a control device for controlling the operation of each movable portion of the robot body 1, and includes a first axis motor driver 7-1, a second axis motor driver 7-2, and a third axis motor driver 7- 3 and a control board (not shown) for performing a predetermined control operation. The control board in the control device 6 includes:
It receives position data from each position detector via each motor driver at regular time intervals Tt, and calculates and outputs an operation command signal to each servo motor based on this. Here, the fixed time Tt is a control sampling period in which the control device 6 digitally controls the robot body 1.

The first-axis motor driver 7-1, the second-axis motor driver 7-2, and the third-axis motor driver 7-3 are provided with first-axis, second-axis, and third-axis servo motors and position detection, respectively. It is a motor driver provided corresponding to the container. Each motor driver has a communication processing unit that performs communication processing with the position detector, and outputs a request signal for requesting acquisition of position data to the corresponding position detector at regular time intervals Ts. This request signal is transmitted to each position detector via the serial communication line 5. Also, the position data output by the corresponding position detector is transmitted to the serial communication line 5.
And supplies it to the control board in a predetermined signal format.

Here, the above-mentioned pairs of the motor drivers and the position detectors operate asynchronously, and during the above-mentioned control sampling period, the pairs of the motor drivers and the position detectors sequentially transmit the position data acquisition request and the position data. Data transmission or retry at the time of data error in addition to these is performed (details will be described later). For this reason, the fixed time Ts is set to a time sufficiently shorter than the control sampling period, and the communication speed of the transmitter, the receiver, the serial communication line 5 and the like provided in each device becomes sufficiently high. I have. For example, T
s is 250 μs, and the communication speed is about 5 Mbps.

Each motor driver has a motor power line (3-1, 3-1) connected to a corresponding servomotor.
3-2, 3-3) are also connected (not shown). Then, the operation command signal output from the control board is converted into a current for driving the servomotor in accordance with the operation command signal, and supplied to each servomotor via each motor power line.

(2) Internal Configuration of Position Detector Next, the internal configuration of the first axis position detector 4-1, the second axis position detector 4-2, and the third axis position detector 4-3 will be described in detail. Will be described. FIG. 2 is a block diagram showing the internal configuration of the position detector. It should be noted that there is no particular difference between the position detectors of the respective axes and that all of them have the same internal configuration. FIG. 2 shows only the internal configuration of one position detector.

In FIG. 1, a resolver 10 is a resolver for detecting a rotational position of a servomotor output shaft, and outputs the detected rotational position to an A / D conversion circuit 11 as an analog signal. The A / D conversion circuit 11 receives an analog signal from the resolver 10, converts the analog signal into digital data, and outputs the digital data. The A / D conversion circuit 11 includes a resolver 10
Is provided with a function of determining whether or not there is an abnormality in the detection result. If the received analog signal is abnormal, an error signal is output.

The rotation detecting circuit 12 is a circuit for detecting the rotation of the servo motor output shaft.
Each time it rotates, it outputs a pulse signal to the counter circuit 13. The counter circuit 13 receives the pulse signal from the rotation detection circuit 12, and counts and outputs the number of rotations of the output shaft of the servo motor. Also, this counter circuit 13
Has a function of determining whether there is an abnormality in the detection result of the rotation detection circuit 12, and outputs an error signal when the received pulse signal is abnormal.

The position detection circuit 14 includes an A / D conversion circuit 11
This is a circuit that receives the rotational position (digital data) output from the controller and the number of rotations output from the counter circuit 13, calculates the position of the movable part operated by the servomotor based on these, and generates position data. .

The A / D conversion circuit 11, counter circuit 13 and position detection circuit 14 are supplied with an operation clock by a timer 15. These circuits perform the above operation in synchronization with the operation clock.

The serial communication circuit 16 includes the position detection circuit 1
4 is a circuit that converts the position data generated in step 4 into a serial signal format and outputs it. This serial communication circuit 1
Numeral 6 converts the position data into a serial signal format every time the operation clock is supplied from the timer 12, and holds the converted position data signal as output position data. That is, every time the operation clock is supplied, the position data for output is updated. Then, upon receiving the request signal, it is determined whether or not the request signal is for itself, and if so, the position data signal held at that time is output to the serial communication line 5. . In order to perform such an operation, the operation clock of the timer 12 is sufficiently shorter than the predetermined time Ts, and the position detector and the motor driver operate asynchronously.

The serial communication circuit 16 also receives an error signal output by the A / D conversion circuit 11 and the counter circuit 13 (see "abnormal" in the figure). Then, if a request signal is received while an error signal is being input, data corresponding to the information to that effect is output. Further, the serial communication circuit 16 resets the A / D conversion circuit 11 and the counter circuit 13 as necessary, for example, when there is a request from the motor driver ("reset" in the figure).
reference).

(3) Mode of Data Communication Next, the mode of data communication in the industrial robot will be described. In this industrial robot, as described above, three position detectors and three motor drivers are one.
The system is daisy-chained to the serial communication line 5, and the serial communication line 5 is a common data communication signal line for all axes. For this reason, address information indicating the communication partner is added to the transmitted / received communication data. FIG. 3 shows an example of communication data according to the embodiment.

In FIG. 3, the upper part shows data included in a request signal from the motor driver to the position detector, and the lower part shows data included in the position data signal from the position detector to the motor driver. As shown in the figure, the communication data transmitted and received between the position detector and the motor driver has a 32-bit packet-like configuration, and the fourth bit (bit 3 in the figure) to the sixth bit (bit 3 in the figure). (Bit 5 in the figure, the same applies hereinafter) includes address information indicating the communication partner. Using such communication data, an address is set for each position detector and motor driver.

Here, each bit information of the communication data mode shown in FIG. 3 will be described with reference to FIG. FIG. 4 shows an example of communication data in the communication data mode shown in FIG.
1 is a request signal (upper stage) requesting the first axis position detector 4-1 to acquire position data, and in response to the request signal, the first axis position detector 4-1 operates the first axis motor driver 7- 1 corresponds to the position data signal (lower stage) to be transmitted.

First, the bit information included in the request signal will be described (see the upper part of FIGS. 3 and 4). First
Bits to third bits are start bits, which are values specific to the communication specifications, for example, "01" as shown in FIG.
0 ". The fourth to sixth bits are address designation bits, and the first to third axis position detectors 4-1 to 4-3.
Is a bit string corresponding to the address that designates In the example shown in the upper part of FIG. 4, it is “001”, which corresponds to the address of the first axis position detector 4-1. The 7th to 26th bits (D19 to D0 in the figure) are not used in the request signal.

The 27th bit and the 28th bit are control signal bits, and are a bit string indicating what kind of signal is included in the packet. In the example in the upper part of FIG. 4, it is “10”, which indicates that this is a request signal. The 29th to 31st bits are CRC signal bits, which are used as cyclic redundancy check codes for detecting data errors in packets. The 32nd bit is a stop bit, which is “1” in the example of FIG.

The request signal as described above is output from the motor driver, and the first
The signal is transmitted to all the position detectors of the axis to the third axis and two motor drivers other than the motor driver. Then, all the position detectors and the two motor drivers receive the request signal, and determine whether or not the signal is transmitted to itself based on the address designation bit.

At this time, the request signal is ignored by the position detector which determines that the signal is not a signal for itself. Further, in the two motor drivers, it is determined that neither signal is for itself, and the request signal is ignored.

On the other hand, the position detector which has determined that the request signal is for itself is stored in the position detector shown in FIG.
The position data signal shown in the lower part is transmitted to the serial communication line 5.
To all the motor drivers of the first to third axes and the position detectors other than the position detector.

In the example of FIG. 4, the request signal in the upper part of FIG. 4 is transmitted to all the position detectors of the first to third axes, the second-axis motor driver 7-2 and the third-axis motor driver 7-3. The second axis position detector 4-2 and the third axis position detector 4
-3, the second axis motor driver 7-2 and the third axis motor driver ignore the request signal. Then, only the first axis position detector 4-1 outputs the position data signal held at that time as shown in the lower part of FIG.
The signals are transmitted via the serial communication line 5 to all the motor drivers of the axis to the third axis, and to the second axis position detector 4-2 and the third axis position detector 4-3.

Next, the bit information of the position data signal transmitted from the position detector as described above will be described (see the lower part of FIGS. 3 and 4). In the position data signal, the first to third start bits, the 29th bit
The bit to the 31st CRC signal bit and the 32nd stop bit are the same as the request signal.

The fourth to sixth address designation bits are a bit string corresponding to the self address of the position detector on the transmitting side. Therefore, in the example of the lower part of FIG. 4, the address of the first axis position detector 4-1 is “001”.

The 7th to 26th bits are position data bits. The position data generated by the position detection circuit 14 and the like and converted into a 20-bit serial signal (D19 to D0) by the serial communication circuit 16 is included.

The 27th and 28th control signal bits are bit strings indicating that the signal included in the packet is a position data signal. In the example in the lower part of FIG. 4, the value is "00", which indicates that this is a position data signal.

The position data signal as described above is transmitted from the position detector to all the motor drivers of the first to third axes and two position detectors other than the position detector.
Then, the position data signal is fetched only by the motor driver determined to be a signal for itself, and is ignored by the other motor drivers and position detectors. The position data signal shown in the lower part of FIG. 4 is taken in only by the first axis motor driver 7-1, and the second axis position detector 4-2, the third axis position detector 4-3, the second axis motor driver It is ignored by the 7-2 and third axis motor drivers.

<Operation> Next, a communication processing operation for performing data communication in the industrial robot having the above configuration will be described. Since the operation mode of the communication processing in the pair of the corresponding position detector and motor driver is the same, the first axis position detector 4 will be described in the following description.
-1 and the first axis motor driver 7-1 will be described only for the communication processing operation, and the second axis position detector 4-
The description of the communication processing operation of the set of the second and second axis motor drivers 7-2 and the set of the third axis motor driver 4-3 and the third axis motor driver 7-3 is omitted. Here, the example shown in FIG. 4 is used as the form of the communication data.

(1) Communication processing operation on the motor driver side First, the communication processing operation on the motor driver side will be described with reference to the flowchart of FIG. FIG.
Indicates a process that is repeatedly performed by the control board, the communication processing unit, and the like on the motor driver side every fixed time Ts, and is started by a timer interrupt every fixed time Ts.

First, in STEP1, it is checked whether there is an error in the communication processing unit of the first axis motor driver 4-1.
If there is an error, predetermined error processing for the communication processing unit error is performed (STEP 2), and if there is no error, the process proceeds to STEP 3.

In STEP 3, the request signal as shown in the upper part of FIG. 4 is output by designating the address "001" of the first axis position detector, and is sent to each position detector via the serial communication line 5. Send a request signal.

After that, the first axis position detector 7-1 for a certain period of time.
Then, a response waiting process for waiting for a position data signal is performed (STEP 4 and STEP 5). The response waiting process first determines whether or not a response has been received in STEP 4, that is, whether or not any signal has been received. Is determined, and if the time has not elapsed, the procedure returns to STEP 4 and repeats the same processing. When the predetermined time, for example, the time of about 50 μs elapses without a response, the determination result in STEP 5 is “YE
The process proceeds to STEP 6 to perform predetermined error processing for a non-response error.

On the other hand, if there is a response within the predetermined time and some signal is received, the result of the determination in STEP 4 is “YES”, and the processing proceeds to STEP 7 and subsequent steps. Then, whether or not there is an error in the communication at this time, that is, in response to the request signal transmitted in STEP 3, a position data signal is transmitted from the first axis position detector, and the position data signal can be appropriately received. Judge whether or not.

In determining this communication content,
First, in STEP 7, it is determined whether the received signal is a reliable position data signal without error. This is performed by referring to the control signal bit of the received signal. If the control signal bit is “00”, “YE”
If the received signal is a reliable position data signal with no error, the control signal bit is set to "00". Therefore, the determination result in STEP 7 is “YES”, and the flow proceeds to STEP 8.

Then, in STEP 8, the received signal is
It is determined whether the data is transmitted from the shaft position detector 4-1. This is performed by referring to the address designation bit of the received signal. If the address designation bit is "001", it is determined to be "YES"; otherwise, it is determined to be "NO". . At this time, if the received signal is a position data signal transmitted from the first axis position detector 4-1, the address designation bit is "001".
, The result of the determination in STEP 8 is “YES”.
And proceed to STEP9.

In STEP 9, a process for taking in information included in the position data bits of the received signal as position data is performed. This processing is performed by converting the position data into a predetermined signal format in a communication processing unit and supplying the signal to a control board or the like. Thus, the first axis motor driver 7-1
The position data of the first axis position detector 4-1 is obtained on the side.

In step 8, the received signal is the first
If it is a position data signal transmitted from a position detector other than the axis position detector 4-1, the address designation bits are bit strings other than "001".
The judgment result of EP8 is "NO". In this case, the position data signal is ignored, and the process returns to STEP 4 to perform the response waiting process again.

On the other hand, if it is determined in STEP 7 that the control signal bit of the received signal is a bit string other than “00”, the determination result is “NO”, and
Proceed to 10. This is because an erroneous position data signal or a signal other than the position data signal is received, and STEP 3
This is a case where a communication error has occurred that an appropriate position data signal has not been received even though the request signal has been transmitted.

In STEP 10, similar to STEP 8 described above,
It is determined whether the received signal has been transmitted from the first axis position detector 4-1. At this time, if the received signal is a signal transmitted from other than the first axis position detector 4-1,
The address designation bits are bit strings other than “001”. As a result, the determination result in STEP 10 becomes “NO”, and the process returns to STEP 4 to perform the response waiting process again. That is, the first axis motor driver 7-1
When a communication error occurs as described above, if the communication error is caused by a response from a device other than the communication partner, the communication error is ignored and no error processing is performed.

However, if the communication error is due to a response from its own communication partner, that is, the received signal is a signal transmitted from the first axis position detector 4-1 and the result of determination in STEP10 is If "YES", error processing as described below is performed.

First, in STEP 11, it is determined whether or not the communication error is a communication data error generated during communication of a response from the first axis position detector 4-1 to the first axis motor driver 7-1. I do. Here, the communication data error includes bit omission of a packet during response communication and the like, and the determination is made based on a CRC signal bit in a received signal.

At this time, if no communication data error has occurred, the result of the determination in STEP 11 is “NO”, and the flow proceeds to STEP 12. This time, the communication error is a communication error response due to a drop in a packet bit or the like during the communication of the request signal from the first axis motor driver 7-1 to the first axis position detector 4-1. It is determined whether or not.

As described above, STEP11 and STEP1
In step 2, the process of identifying the form of the communication error is performed. If the communication error cannot be identified as any of the communication data error and the communication error response, the result of the determination in step 12 is "NO" and the process proceeds to step 13. Then, it is considered that some abnormality has occurred on the first axis position detector 4-1 side, and predetermined error processing is performed.

On the other hand, if the communication error is one of the communication data error and the communication error response, the processing after STEP 14 is performed. That is, if a communication data error has occurred, STEP 1
If the result of the determination in step 1 is "YES" and the operation proceeds to step 14, the communication error response is returned.
The result of the determination at 12 is "YES" and the operation proceeds to STEP14.

In STEP 14, it is determined whether the number of retransmissions of the request signal does not exceed a predetermined number of retry times. The number of retransmissions of the request signal referred to here means that the position data signal cannot be obtained even though the request signal has been transmitted once after the communication processing of FIG. 5 is started, and the transmission (retry) of the request signal is performed again. This is the number of times that communication has been performed, and is 0 at the beginning of the communication process. Also, the retry limit number is a preset upper limit of the number of retransmissions as a number of times that a request signal can be retransmitted.

Here, it is assumed that the communication processing operation of FIG. 5 is performed at every fixed time Ts, and is performed asynchronously by a set of the position detectors of the first to third axes and the motor driver. Therefore, the retry limit number includes the time T
Set the number of retransmissions that can be performed during s / 3 or less. still,
When changing the length of time for performing data communication for each axis as needed, the number of retries may be different for each axis.

In STEP 14, when the number of retransmissions of the request signal is smaller than the retry limit set in this way, the determination result is "NO". Then, the retry counter is incremented by one (STEP 1).
5) After returning to STEP 3, the request signal is retransmitted, and the processing after STEP 3 is performed again. In this manner, until the position data signal from the first axis position detector 4-1 is properly received, the determination of the error in the communication content, the identification of the error form, and the retransmission of the request signal are repeated.

If the number of retransmissions of the request signal exceeds the retry limit number, the result of determination in STEP 14 is "YES", and the flow advances to STEP 16 to perform predetermined error processing for a retry over error.

(2) Communication Processing Operation on the Position Detector Next, the communication processing operation on the position detector will be described with reference to the flowchart in FIG. FIG. 6 shows the first
In the axis position detector 4-1, the first axis motor driver 4
2 shows a communication processing operation started when a request signal from -1 is received.

First, if any signal is received by the first axis position detector 4-1, it is determined in STEP 21 whether the received signal is a signal for itself. This is performed by referring to the address designation bit of the received signal. If the address designation bit is "001", it is determined to be "YES"; otherwise, it is determined to be "NO". . Therefore, assuming that the received signal is not for the first axis position detector 4-1, the address designation bit is a bit string other than "001". Finish and ignore the received signal.

On the other hand, the received signal is transmitted to the first axis position detector 4-1.
Since the address designation bit is "001", the result of determination in STEP21 is "YES", and the flow proceeds to STEP22.

At STEP 22, it is determined whether or not there is an error in the communication contents at this time. That is, the above STE
It is determined whether the received signal determined to be for itself (the first axis position detector 4-1) in P21 is a reliable request signal without error. This is performed by referring to the control signal bit of the received signal. If the control signal bit is "10", the judgment is "YES"; otherwise, the judgment is "NO". .

Here, assuming that the received signal is a reliable request signal having no error, the control signal bit is "10", so that the determination result in STEP22 is "YES", and the process proceeds to STEP23.

In STEP 23, the position data signal is transmitted to the first
It is transmitted to the shaft motor driver 7-1. This is performed by the serial communication circuit 16 in the first axis position detector 4-1 outputting the position data signal held at that time to the serial communication line 5.

On the other hand, if the control signal bit of the received signal is a bit string other than "10", ST
The decision result in EP22 is "NO", and the routine proceeds to STEP24. This is a case where a communication error has occurred that a request signal from the first-axis motor driver 7-1 to the first-axis position detector 4-1 was not properly transmitted and received.

In STEP 24, the communication error is transmitted from the first axis motor driver 7-1 to the first axis position detector 4-1.
It is determined whether or not a communication data error has occurred during the communication of the request signal to. Here, similarly to the above, the communication data error includes dropped bits of the packet during the request communication, and the determination is made based on the CRC signal bit in the received signal.

At this time, if a communication data error has occurred, the result of determination in STEP 24 is “YES”, and the flow proceeds to STEP 25. Then, a response indicating that a communication data error has occurred is sent to the first axis motor driver 7-1.
And ends the processing.

On the other hand, if no communication data error has occurred and any other error has occurred, the STE
The determination result of P24 is "NO", and the flow proceeds to STEP26. This is a case where some abnormality has occurred on the first axis position detector 4-1 side, so a position detector error response notifying the fact is transmitted to the first axis motor driver 7-1, and the processing is performed. finish.

As described above, data communication is performed in the set of each position detector and the motor driver connected in a daisy chain by one system serial communication line 5. Here, if two or more motor drivers simultaneously transmit request signals, two or more servo motors simultaneously transmit position data signals, or
When the request signal of the axis motor driver 7-3 and the position data signal of the first axis position detector 4-1 are transmitted at the same time, the communication data battings in the serial communication line 5, and the data disappears or the data is relied on. This leads to a decrease in sex.

In this industrial robot, each set of the position detector and the motor driver operates asynchronously.
Such a situation may actually occur. Therefore,
In order to perform more reliable communication, for example, a signal may be transmitted to notify the other group that each group is performing communication. Specifically, a BUS connecting each pair
A Y signal line is provided, and while a certain group is communicating, "BU" indicating that the right to use the serial communication line 5 is acquired.
The SY ″ signal may be transmitted via the BUSY signal line, and the pair receiving the SY ″ signal may not perform communication.

In the above embodiment, for convenience, 3
Although the description has been given of an industrial robot having an axis servo system as an example, other industrial robots and machine tools having various servo systems such as 2-axis, 6-axis, and 8-axis,
In the chip mounter device or the like, the position detector and the motor driver may be daisy-chained by one serial communication line 5 to perform the data communication as described above. Further, for example, when the serial communication lines of the six-axis servo system cannot be formed into one system due to the wiring, two serial communication lines of three axes may be provided.

Further, since the position detectors are also connected to each other by one serial communication line, the position detectors mutually monitor errors and the like during a time period when there is no request signal from the motor driver. You can also. By doing so, the effect of improving the reliability with respect to the abnormality of the position detector is obtained.

In addition, in the position detector in the above embodiment, a resolver is used to detect the rotational position of the output shaft of the servomotor, but an optical encoder, a magnetic encoder, or the like may be used in addition to this. Good.

It should be noted that there are also position detectors which store multi-rotation information of the position detector in a counter and can detect an absolute position.
In a system equipped with such a position detector, a battery is mounted in order to store multi-rotation information in a counter, and this battery is often used when the power is turned off, that is, as a backup during system stop. In this case, a battery is usually prepared for each position detector. However, according to the present invention, since a single serial communication line is provided as described above, a battery for backup can be covered by a single battery by connecting a battery via this. It becomes possible.

[0076]

As described above, according to the present invention, a plurality of detecting means for detecting the operating state of each movable part, and a plurality of detecting means provided in the control device corresponding to each of the detecting means are provided. Since the communication with the drive control unit is performed by one signal line, twisting, bending, vibration,
The effect of minimizing a decrease in data reliability due to contact or the like and improving the degree of freedom of signal line routing can be obtained.

Further, since communication between the detecting means is also possible, it is possible to monitor an abnormality between the detecting means.
It is possible to improve the reliability with respect to the abnormality of the detection means. In addition, by using one signal line, the number of steps required to provide the signal line can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a configuration of an industrial robot according to one embodiment of the present invention.

FIG. 2 is a block diagram showing an internal configuration of a position detector according to the embodiment.

FIG. 3 is a diagram showing a communication data mode in the embodiment.

FIG. 4 is a diagram showing an example of communication data in the communication data mode shown in FIG.

FIG. 5 is a flowchart showing a communication processing operation on the motor driver side.

FIG. 6 is a flowchart showing a communication processing operation on the position detector side.

[Explanation of symbols]

 1 Robot main body 2-1 First axis servo motor 2-2 Second axis servo motor 2-3 Third axis servo motor 4-1 First axis position detector 4-2 Second axis position detector 4-3 Third Axis position detector 5 Serial communication line 6 Controller 7-1 First axis motor driver 7-2 Second axis motor driver 7-3 Third axis motor driver

Claims (1)

[Claims] 1. An industrial robot having a plurality of movable parts, wherein a control device instructs an operation of each of the plurality of movable parts, wherein one system provided between the plurality of movable parts and the control device. And a plurality of detection means provided corresponding to each of the plurality of movable parts, for detecting an operation state of the movable part, and in the control device, corresponding to each of the plurality of detection means. A plurality of drive control units for controlling the driving of the movable unit, wherein each of the plurality of detection units receives an instruction signal from the control device via the signal line, and the instruction signal is determined by itself. In the case of specifying and requesting a detection result, a detection result signal with data specifying itself is output to the signal line, and the plurality of drive control units each include a detection unit corresponding to itself. The instruction signal with the data to be specified is Output to the signal line, receive the detection result signal via the signal line, and select the detection result signal from the corresponding detecting means by the data attached to the detection result signal to determine the detection result. An industrial robot characterized by being obtained.