JP6607098B2 - Speed monitoring device and speed monitoring method - Google Patents

Description

  The present invention relates to a speed monitoring device and a speed monitoring method.

  The machine tool includes a numerical control device and a safety control device. The safety control device includes a speed monitoring unit. The speed monitoring unit monitors the operation speed of each axis of the machine tool, and even if the numerical control device outputs an incorrect speed command, the operation of the machine tool is stopped before the harm occurs. The speed monitoring unit (safety unit) of the servo system described in Patent Document 1 is abnormal if there is an unacceptable difference by comparing the position information feedback value from the encoder connected to the servo motor and the speed command value of the servo control unit. Is determined.

Japanese Patent No. 5367623

  The position information feedback value and the command value coincide with each other if there is a 1: 1 connection between the speed monitoring unit and the servo control unit. However, in the case of a connection such as a fieldbus having a plurality of connections and one or a plurality of communication between them, due to bugs in other servo control units and communication circuits, for example, to a motor that operates at the same speed The command value may be mistakenly transmitted to the speed monitoring unit. In this case, the speed monitoring unit may operate the machine tool without detecting any abnormality. The state in which the motor moves at the same speed may occur depending on the operation program, and always occurs in a machine tool configured so that the two axes move synchronously. Since the servo system described in Patent Document 1 cannot identify the connection partner, it cannot be said that the speed monitoring unit and the servo control unit are not safe unless they are connected 1: 1. Therefore, the servo system becomes an expensive system because the speed monitoring unit is required by the number of servo motors connected.

  An object of the present invention is to provide a speed monitoring apparatus and a speed monitoring method capable of monitoring the speeds of a plurality of servo motors with a single speed monitoring unit.

  A speed monitoring device according to claim 1 is provided corresponding to each of the plurality of servo motors, a control unit that outputs a command signal for driving and controlling each of the plurality of servo motors, and position information of the servo motors Are provided corresponding to each of the plurality of servo motors and connected to the control unit and the encoder so as to be able to communicate with each other, the command signal from the control unit, A plurality of servo control units for driving the servo motor so as to follow the speed command value by generating a speed command value of the servo motor using the position information from the encoder; The servo controller is communicably connected to obtain the speed command value generated by the servo controller for each servo motor, In a speed monitoring device comprising a speed monitoring unit that intercepts communication with an encoder to acquire the position information, and compares and monitors the acquired speed command value and the position information, the plurality of servo control units Each of them responds to the encoder by request information transmitting means for transmitting the request information for requesting the position information of the servo motor, and the encoder receiving the request information transmitted by the request information transmitting means in response. A speed command for transmitting the speed command value generated based on the position information receiving means for receiving the position information, the command signal, and the position information received by the position information receiving means to the speed monitoring unit. A plurality of value transmitting means and identification information providing means for assigning identification information for identifying the servo control unit to the request information and the speed command value, respectively. Each of the encoders, when receiving the request information transmitted by the request information transmitting means, adds the identification information given to the request information to the position information that is a response to the received request information. Position information is returned to the servo control unit, and the speed monitoring unit communicates the identification information given to the speed command value received from the speed command value transmitting means, and communication between the servo control unit and the encoder. When the identification information match determination means for determining whether or not the identification information given to the position information obtained by intercepting matches, and when the identification information match determination means determines that the identification information does not match, And a stop signal output means for outputting a stop signal for stopping the drive of the servo motor to the servo control unit. The speed monitoring device can detect a mismatch between communication partners of a plurality of servo controllers and encoders connected to each other by comparing and verifying the identification information given to the received speed command value and the intercepted position information. In the case of mismatch, the speed monitoring device outputs a stop signal, so that malfunction can be prevented. By determining the coincidence of the identification information, it is possible to quickly detect an abnormality with different communication partners, so that the speeds of a plurality of servo motors can be monitored with a single speed monitoring unit. Since only one speed monitoring unit is required for a plurality of servo control units, connection via a field bus or the like is possible. The speed monitoring device can reduce the cost as compared with a system in which speed control units are individually prepared for all servo control units. Note that the position information that the speed monitoring unit compares with the speed command value is the position information from the encoder per unit time, and thus is the current speed. Therefore, the speed monitoring unit can monitor by comparing the speed command value with the current speed.

  According to a second aspect of the present invention, in addition to the configuration of the first aspect of the invention, each of the plurality of servo control units includes timer information that can specify a communication time and the identification information. Timer information adding means for assigning the request information and the speed command value, respectively, each of the plurality of encoders receives the request information transmitted by the request information transmitting means, and responds to the received request information The position information to which the identification information given to the request information and the timer information are given to the position information is returned to the servo control unit, and the speed monitoring unit is received from the servo control unit. It is determined whether the timer information given to the speed command value matches the timer information given to the position information acquired by intercepting communication between the servo control unit and the encoder. Timer information coincidence determining means, and the stop signal output means further outputs the stop signal to the servo control unit when the timer information coincidence determination means determines that the timer information does not match. To do. The speed monitoring device compares and verifies the identification information given to each of the received speed command value and the intercepted position information, and compares and verifies the timer information given to each of the speed command value and the position information. It is also possible to detect inconsistencies in time.

  In addition to the configuration of the invention according to claim 2, the speed monitoring device according to claim 3 adds the error detection code to the control unit, the servo control unit, and the speed monitoring unit each time a packet is communicated with each other. An error detection code providing means for providing an error detection code to the request information and the speed command value provided by the identification information and the timer information. Each of the plurality of encoders, when receiving the request information transmitted by the request information transmitting means, added to the request information to the position information that is a response to the received request information The identification information, the timer information, and the position information provided with the error detection code are returned to the servo control unit, and the speed monitoring unit transmits the speed command value transmission unit. Whether or not the error detection code given to the speed command value received from the code and the error detection code given to the position information obtained by intercepting communication between the servo control unit and the encoder match. An error detection code match determination means for determining, and the stop signal output means further outputs the stop signal to the servo control unit when the error detection code match determination means determines that the error detection code does not match. It is characterized by that. The speed monitoring device can further detect an abnormality on the communication path by comparing and verifying the error detection code assigned to the received speed command value and the intercepted position information.

  According to a fourth aspect of the present invention, in addition to the configuration of the invention according to any one of the first to third aspects, the speed monitoring unit includes the speed command value received from the speed command value transmitting unit, and the servo. Speed determination for comparing a current speed value obtained by converting the position information acquired by intercepting communication between the control unit and the encoder into a speed value and determining whether or not a discrepancy exceeds a predetermined allowable value The stop signal output means further outputs the stop signal to the servo controller when the speed determination means determines that a mismatch has occurred exceeding the allowable value. And It is abnormal when the difference between the speed command value and the current speed value exceeds a predetermined range. In this case, since the speed monitoring device can stop the drive of the servo motor, safety can be improved.

  According to a fifth aspect of the present invention, in addition to the configuration of the invention according to any one of the first to fourth aspects, the speed monitoring unit includes the speed command value received from the speed command value transmitting unit, and the servo. Upper limit determination means for determining whether or not any of the current speed values obtained by converting the position information acquired by intercepting communication between the control unit and the encoder into speed values is equal to or less than a predetermined upper limit value. The stop signal output means further outputs the stop signal when the upper limit value determining means determines that at least one of the speed command value and the current speed exceeds the predetermined upper limit value. It outputs to a servo control part. When at least one of the speed command value and the current speed value exceeds a predetermined upper limit value, the servo motor is in an overspeed state. In this case, since the speed monitoring device can stop the drive of the servo motor, safety can be improved.

  According to a sixth aspect of the present invention, in addition to the configuration of the invention according to any one of the first to fifth aspects, the speed monitoring unit has determined that the identification information coincidence determining unit does not match the identification information. Time determining means for determining whether or not the state has continued for a certain time or more is provided, and the stop signal output means further includes a state in which the time determining means has determined that the identification information is inconsistent for the certain time or longer. When it is determined that the stop signal is being generated, the stop signal is output to the servo control unit. Therefore, the speed monitoring device can improve the identification accuracy of the communication partner.

  According to a seventh aspect of the present invention, in addition to the configuration of the invention according to any one of the first to fifth aspects, the speed monitoring unit determines that the identification information coincidence determining unit does not match the identification information. The stop signal output means further determines that the determination that the identification information is inconsistent continues for a specified number of times. In this case, the stop signal is output to the servo control unit. Therefore, the speed monitoring device can improve the identification accuracy of the communication partner.

  The speed monitoring method according to claim 8 is provided corresponding to each of the plurality of servo motors, a control unit that outputs a command signal for driving and controlling each of the plurality of servo motors, and position information of the servo motors Are provided corresponding to each of the plurality of servo motors and connected to the control unit and the encoder so as to be able to communicate with each other, the command signal from the control unit, A plurality of servo control units for driving the servo motor so as to follow the speed command value by generating a speed command value of the servo motor using the position information from the encoder; The servo controller is communicably connected to obtain the speed command value generated by the servo controller for each servo motor, In the speed monitoring method of a speed monitoring apparatus comprising: a speed monitoring unit that intercepts communication with an encoder to acquire the position information, and compares and monitors the acquired speed command value and the position information. Each of the servo control units includes a request information transmission step for transmitting request information for requesting the position information of the servo motor to the encoder, and the encoder that has received the request information transmitted in the request information transmission step. The speed command value generated on the basis of the position information receiving step for receiving the position information returned in response, the command signal, and the position information received in the position information receiving step is sent to the speed monitoring unit. A speed command value transmitting step for transmitting, and an identification information giving step for giving identification information for identifying the servo control unit to the request information and the speed command value, respectively. Each of the plurality of encoders, when receiving the request information transmitted in the request information transmitting step, adds the identification information added to the request information to the position information that is a response to the received request information. Is returned to the servo control unit, and the speed monitoring unit receives the speed command value transmitted in the speed command value transmitting step and receives the identification given to the received speed command value. An identification information match determination step for determining whether the information matches the identification information given to the position information acquired by intercepting communication between the servo control unit and the encoder; and the identification information match determination A stop signal output step of outputting a stop signal for stopping the drive of the servo motor to the servo control unit when the identification information is determined to be inconsistent in the step. The The speed monitoring apparatus can obtain the effect described in claim 1 by performing the above method.

  You may combine the one part structure of the said Claims 1-7 arbitrarily.

1 is a block diagram showing an electrical configuration of a servo system 1. FIG. FIG. 3 is a functional block diagram showing an internal configuration of a servo amplifier. The figure which gives CRC code (1) and (2) to data. The figure which gives CRC code (1a) and (2a) to the packet of a speed command. The figure which gives CRC code (1b) (2b) to the packet of request information. The figure of the packet of the position information which encoder 6 returns. The flowchart of a check process. The figure of the servo system 100 (modification). The flowchart of the 1st modification of a check process. The flowchart of the 2nd modification of a check process.

  Embodiments of the present invention will be described with reference to the drawings. The configuration, processing, and the like of the system described below are merely illustrative examples, and are not intended to be limited to only those unless otherwise specified. The drawings are used to explain technical features that can be adopted by the present invention.

  The configuration of the servo system 1 will be described with reference to FIG. The servo system 1 is a system for driving a machine tool (not shown), for example. For example, the machine tool performs cutting of a work material by relatively moving a tool and a work material (not shown) in three axial directions of X, Y, and Z that are orthogonal to each other. The servo system 1 includes a plurality of motor mechanism units U1 to Un, a numerical control device 2, and a safety control device 3. The motor mechanism units U1 to Un each include various servomotors 5 (hereinafter referred to as motors 5) for driving the machine tool. The various motors 5 are, for example, any of an X-axis motor, a Y-axis motor, a Z-axis motor, a main shaft motor, a magazine motor of a tool changer, etc. (not shown). The X-axis motor, the Y-axis motor, and the Z-axis motor move the main shaft and the work material relative to each other in three axis directions. The spindle motor is a motor that rotationally drives a spindle on which a tool is mounted.

  The numerical controller 2 controls the driving of the motor mechanism units U1 to Un based on the NC program. The NC program is composed of a plurality of lines including various control commands, and controls various operations including axis movement of the machine tool, tool change, etc. in line units. The safety control device 3 monitors the respective states of the motor mechanism units U1 to Un and urgently stops the operation of the machine tool when an abnormality is detected.

  The configuration of the motor mechanism unit U1 will be described with reference to FIG. The present embodiment includes n motor mechanism units U1 to Un, all of which have the same configuration. Therefore, this embodiment attaches | subjects the same code | symbol to these and demonstrates the motor mechanism part U1 as an example. The motor mechanism unit U1 includes a motor 5, an encoder 6, and a servo amplifier 7. The motor 5 is an AC servo motor, for example, and is a motor of the above-described machine tool. The encoder 6 is electrically connected to the motor 5 and detects the operation of the servo motor 5. The encoder 6 generates a feedback signal indicating the detected operation of the servo motor 5 and outputs it to the servo amplifier 7. The feedback signal includes, for example, position information on the rotational position (angle) of the rotation shaft of the servo motor 5, information on the rotation speed of the rotation shaft, and the like. As the encoder 6, a general incremental type encoder, an absolute type encoder, or the like can be applied.

  The servo amplifier 7 includes a servo controller 10, an STO circuit 11, and a power control element 12. The servo controller 10 is electrically connected to the encoder 6. The servo controller 10 is connected to the numerical controller 2 via a communication path (not shown) such as a field bus. The servo controller 10 generates a control waveform signal based on a control command (an example of a command signal of the present invention) from the numerical controller 2 and a feedback signal from the encoder 6. The internal processing of the servo controller 10 will be described later. The servo controller 10 outputs the generated control waveform signal to the power control element 12 via the STO circuit 11. The power control element 12 is connected between the motor 5 and the power supply 15. The power source 15 is, for example, an AC power source. The power control element 12 includes, for example, a converter and an inverter (not shown). The converter converts AC power into DC. The inverter converts direct current into a control current based on the control waveform signal and outputs it to the motor 5. Therefore, the motor 5 is driven based on the control of the servo controller 10. The STO circuit 11 has a safe torque-off function. When the STO circuit 11 receives an STO command for stopping operation from the safety control device 3, the STO circuit 11 forcibly turns off the drive signal of the power transistor in the circuit, thereby generating a control current output from the power control element 12 to the motor 5. Cut off. Therefore, the output torque of the motor 5 is turned off and the motor 5 stops. The STO circuit 11 is not limited to a power transistor, and may be, for example, an IGBT (insulated gate bipolar transistor) or a relay.

  The internal processing of the servo controller 10 will be described with reference to FIG. The servo controller 10 can communicate with the encoder 6 and the numerical controller 2. The servo controller 10 transmits request information to the encoder 6 so as to output the position information of the motor 5 (see arrow K1 in FIG. 2). The encoder 6 returns position information to the request information. The servo controller 10 receives the position information from the encoder 6 via the communication circuit 46 (see arrow K2 in FIG. 2). The servo controller 10 always communicates with the numerical controller 2 via the communication path. The numerical controller 2 generates, for example, an axis movement command based on the control command of the NC program, and outputs the generated movement command to the servo controller 10.

  The servo controller 10 includes a position controller 41, a speed controller 42, a current controller 43, a speed converter 44, communication circuits 45 and 46, and the like. The position control unit 41 receives a movement command from the numerical control device 2 via the communication circuit 45. The position control unit 41 calculates a position deviation between the target position of the movement command from the numerical controller 2 and the position information from the encoder 6, and calculates a speed command by multiplying the position deviation by a position proportional gain. The speed conversion unit 44 differentiates the position information from the encoder 6 and converts it into speed information that is actual speed information. The speed control unit 42 calculates a speed deviation between the value of the speed command calculated by the position control unit 41 and the speed information converted by the speed conversion unit 44. The speed control unit 42 integrates the speed deviation by multiplying the calculated speed deviation by the speed proportional gain and the current command (proportional) obtained by integrating the speed deviation and multiplying the integration result by the speed integral gain. Integration) is added to generate a torque command. The current control unit 43 outputs a control waveform signal to the power control element 12 via the STO circuit 11 based on the torque command generated by the speed control unit 42. Therefore, the motor 5 is driven so as to follow the speed command calculated by the position control unit 41. The speed command value corresponding to the speed command calculated by the position control unit 41 is an example of the speed command value of the present invention.

  The position control unit 41 transmits the calculated speed command to the safety control device 3 using a communication path with the numerical control device 2 (see arrow K3 in FIG. 2). The speed command packet is transmitted to the safety control device 3 via another relay such as a servo amplifier (not shown). The repeater only relays the speed command packet and does not change the contents.

  The configuration and operation of the safety control device 3 will be described with reference to FIG. The safety control device 3 includes a CPU 31, a ROM 32, a RAM 33, and the like. The CPU 31 controls the operation of the safety control device 3. The ROM 32 stores various programs. The RAM 33 temporarily stores various data. The safety control device 3 receives the speed command packet transmitted by the position controller 41 of the servo controller 10 and stores it in the RAM 33. The safety control device 3 intercepts communication between the servo controller 10 and the encoder 6, thereby acquiring a request information packet to the encoder 6 and a position information packet returned from the encoder 6, and stores them in the RAM 33.

  The safety control device 3 periodically acquires door opening / closing information from a door switch 25 provided on a door of a protective cover of a machine tool (not shown) in addition to a request information packet and a position information packet, and stores them in the RAM 33. . The protective cover surrounds the periphery of the machine tool to prevent the chips and cutting fluid from being scattered outside. By opening the door of the protective cover, the operator can exchange the work material fixed on the table installed inside the protective cover. By closing the door of the protective cover, the machining area and the outside are shut off, so that the workpiece can be safely cut. The door switch 25 detects opening / closing of the door. The door opening / closing information is information indicating the opening / closing of the door that the door switch 25 transmits to the safety control device 3.

  As described above, the RAM 33 of the safety control device 3 stores various data such as a speed command packet, a request information packet, a position information packet, and door opening / closing information. The safety control device 3 can individually detect abnormalities in the plurality of motor mechanism units U1 to Un by executing a check process (see FIG. 6) described later on these packets and the door opening / closing information at a predetermined cycle.

  The unique ID information and timer information that the servo controller 10 gives to the packet will be described with reference to FIGS. 2, 4, and 5. The position controller 41 of the servo controller 10 sets the unique ID information and timer information in the calculated speed command packet (see K4 and K5 in FIG. 2, see FIG. 4 (1)). The unique ID information is information for identifying the individual servo amplifier 7. The timer information is information indicating communication time. The position control unit 41 also sets unique ID information and timer information in the request information packet to be transmitted to the encoder 6 (see FIG. 5A). The encoder 6 sets the position information of the motor 5 as a response to the request information, the unique ID information set in the request information packet, and the timer information in a packet returned to the request information packet. To do. The safety control device 3 compares the unique ID information set in these packets with the timer information in a check process (see FIG. 7) described later. If the unique ID information coincides with the timer information, the safety control device 3 indicates that the request information, the position information from the encoder 6, and the speed command calculated by the servo controller 10 are the same servo amplifier 7, motor 5, encoder. It can be confirmed that these are passed from 6 systems (same motor mechanism part Un).

  The CRC error detection method employed by the communication system of the servo system 1 will be described with reference to FIGS. The communication system of the servo system 1 employs CRC (Cyclic Redundancy Code). CRC is one of well-known error detection methods, and detects errors using a remainder (surplus) obtained by dividing data by a certain constant. In the present embodiment, an inspection value is calculated before data transmission and recording, and one CRC code is added to the data itself. Recalculate the CRC code at the same location after reception and reading, and if it matches the CRC code added in advance, it turns out that there is no error, and if it does not match, it turns out that part of the data has been altered in the middle . Since the CRC code is a code for error detection, the error cannot be corrected.

  For example, as shown in FIG. 3 (1), the data transmission source attaches CRC (1) to the data itself, and transmits the data including CRC (1) as a single packet. When transmitting data, a header is added to the head of the data. As shown in FIG. 3 (2), when data is exchanged at the physical layer level, the physical layer gives CRC (2) to the outside of the packet. Therefore, even if the data change occurs at the relay point of the communication path and the CRC (2) is reassigned, the detection can be performed by the CRC (1). The physical layer defines a physical connection / transmission method of the network. In the present embodiment, the physical layer includes, for example, communication circuits 45 and 46, and relay points (not shown) of the communication path.

  FIG. 4 (1) shows an example of a speed command packet transmitted from the servo controller 10 to the safety control device 3. The position controller 41 of the servo controller 10 transmits the calculated speed command with a CRC (1a) as one packet for each data to which the unique ID information and the timer information are added (see K6 in FIG. 2). . The communication circuit 45 adds CRC (2a) to the outside of the packet in FIG. 4 (1) (see FIG. 4 (2)). The speed command packet is transmitted to the safety control device 3 via a communication path with the numerical control device 2. The safety control device 3 receives the speed command packet of FIG. Since the packet of the speed command passes through the communication path with the numerical control device 2, there is a possibility that the speed command that is a part of the data may be altered due to, for example, a bug in the application layer that controls communication in the numerical control device 2. is there. Even if the physical layer reassigns CRC (2a) after the speed command has been modified, the safety control device 3 can detect CRC (1a), so it is easy to check whether data has been altered during communication. it can.

  FIG. 5 (1) shows an example of a request information packet that the servo controller 10 transmits to the encoder 6. The position control unit 41 of the servo controller 10 transmits the request information with a CRC (1b) as one packet for each data to which the unique ID information and the timer information are added. The communication circuit 46 adds CRC (2b) to the outside of the packet shown in FIG. 5 (1) (see FIG. 5 (2)). The safety control device 3 acquires the request information packet shown in FIG. Even if the physical layer in the middle of communication reassigns the CRC (2b) to the request information packet acquired by interception, the safety control device 3 detects the CRC (1b), thereby modifying the data in the middle of the communication. It can be confirmed whether or not there was.

  The encoder 6 receives from the servo controller 10 the request information shown in FIG. The encoder 6 deletes the header and the CRC (2b), and the position of the motor 5 that is a response to the request information after the same unique ID information, timer information, request information, and CRC (1b) as the request information packet. Give information. Therefore, the encoder 6 returns the position information packet shown in FIG. 6 to the servo controller 10. The safety control device 3 acquires the position information packet by interception.

  With reference to FIG. 2, the check process which the safety control apparatus 3 performs is demonstrated. The CPU 31 (see FIG. 2) of the safety control device 3 receives the speed command packet transmitted from the position control unit 41 of the servo controller 10 and stores it in the RAM 33. The CPU 31 intercepts communication between the servo controller 10 and the encoder 6, so that the request information packet transmitted from the servo controller 10 to the encoder 6 and the position information packet returned from the encoder 6 to the servo controller 10 are transmitted. Acquired and stored in the RAM 33. The CPU 31 periodically acquires door opening / closing information from the door switch 25 provided on the door of the protective cover of the machine tool, and stores it in the RAM 33.

  When the servo system 1 is activated and the cutting of the work material based on the NC program by the numerical controller 2 is started, the CPU 31 reads the check program stored in the ROM 32 at a predetermined cycle and executes this process.

  The CPU 31 reads all the various packets and door opening / closing information stored in the RAM 33 (S11). The CPU 31 refers to the door opening / closing information and determines whether or not the door of the protective cover is closed (S12). When the door is open (S12: NO), since the door is open during the operation of the machine tool, the CPU 31 displays an error on a display unit provided on an operation panel (not shown) of the servo system 1 (S19). Then, the STO command for stopping the operation is output to the STO circuit 11 of any motor mechanism unit U1 to Un that is determined to be stopped (S20). The STO circuit 11 cuts off the control current that flows from the power control element 12 to the servo motor 5. Since the operation of the machine tool is urgently stopped, safety can be ensured. For example, because of the configuration of the machine tool, it is not necessary to stop a portion that is sufficiently away from the human work area, and thus the CPU 31 can continue the operation of the motor mechanism unit Un at a portion that does not need to be stopped. The CPU 31 ends this process. In the setting state of the machine tool, the CPU 31 may perform control to move at a low speed when the door is open.

  When the door is closed (S12: YES), the CPU 31 determines whether or not the CRC codes of the speed command packet, the request information packet, and the position information packet are normal (S13). For example, in the speed command packet shown in (2) of FIG. 4, one CRC (1a) is assigned to the unique ID information, the timer information, and the speed command data. If a CRC code that cannot be detected or is different from CRC (1a) is detected, the data or CRC (1a) has been rewritten, and therefore CRC is abnormal (S13: NO). In this case, since data may be rewritten during communication, the CPU 31 displays an error on the display unit provided on the operation panel (S19), and determines that the operation stop STO command is required to be stopped. It outputs to the STO circuit 11 of arbitrary motor mechanism parts U1-Un (S20). Since the operation of the machine tool is urgently stopped, safety can be ensured. The CPU 31 ends this process.

  When the CRC codes of the various packets are all normal (S13: YES), the CPU 31 determines whether or not the unique ID information of the speed command packet, the request information packet, and the position information packet matches each other. (S14). For example, if any one of the three packets does not match the unique ID information (S14: NO), there is a possibility that any packet is obtained from the servo controller 10 of another motor mechanism unit Un. Yes, the communication partner may be wrong. Therefore, the CPU 31 displays an error on the display unit provided on the operation panel (S19), and outputs an operation stop STO command to the STO circuit 11 of any motor mechanism unit U1 to Un that is determined to be stopped. (S20). Since the operation of the machine tool is urgently stopped, safety can be ensured. The CPU 31 ends this process.

  When all the unique ID information matches (S14: YES), the speed command packet, the request information packet, and the position information packet are the same servo amplifier 7, motor 5 and encoder 6 system (the same motor). It can be seen that it is passed from the mechanism unit Un). Therefore, the CPU 31 determines whether or not the timer information of the speed command packet matches the position information packet (S15). Note that the timer information match is not a perfect match, and may be regarded as a match if the time difference of the timer information is within the allowable time of the control cycle. If the timer information does not match (S15: NO), the communication time of the speed command packet and the communication time of the position information packet do not match, so the communication time is abnormal. Therefore, the CPU 31 displays an error on the display unit provided on the operation panel (S19), and outputs an operation stop STO command to the STO circuit 11 of any motor mechanism unit U1 to Un that is determined to be stopped. (S20). Since the operation of the machine tool is urgently stopped, safety can be ensured. The CPU 31 ends this process.

  If the timer information matches (S15: YES), the CPU 31 compares the command speed with the current speed and determines whether they match (S16). The command speed is a speed command value specified by the speed command. The current speed is obtained by converting position information per unit time from the encoder 6. If the difference between the command speed and the current speed exceeds the predetermined range, they do not coincide with each other (S16: NO), and thus the internal processing of the servo controller 10 is abnormal. Therefore, the CPU 31 displays an error on the display unit provided on the operation panel (S19), and outputs an STO command for stopping the operation to the STO circuit 11 of any motor mechanism unit U1 to Un that is determined to be stopped. (S20). Since the operation of the machine tool is urgently stopped, safety can be ensured. The CPU 31 ends this process.

  If the difference between the command speed and the current speed is within the predetermined range, they match each other (S16: YES), so the CPU 31 determines whether both the command speed and the current speed are less than or equal to the upper limit value (S17). If either the command speed or the current speed or both exceed the upper limit value (S17: NO), it is abnormal because the speed is exceeded. Therefore, the CPU 31 displays an error on the display unit provided on the operation panel (S19), and outputs an operation stop STO command to the STO circuit 11 of any motor mechanism unit U1 to Un that is determined to be stopped. (S20). Since the operation of the machine tool is urgently stopped, safety can be ensured. The CPU 31 ends this process.

  When both the command speed and the current speed are less than or equal to the upper limit value (S17: YES), the CPU 31 outputs an STO command for permitting operation to the STO circuit 11. Therefore, the machine tool can continue to operate. As described above, the servo system 1 can detect the abnormality of the communication partner, the abnormality of the communication time, and the abnormality of the communication by performing the verification of the unique ID information, the verification of the timer information, the verification of the CRC code, etc. Each abnormality of the parts U1 to Un can be determined individually. Therefore, the servo system 1 can monitor the speeds of the plurality of motors 5 with one safety control device 3. Since the servo system 1 does not need to prepare safety control devices for the number of motor mechanism units U1 to Un, the cost for the system can be reduced.

  In the above description, the servo system 1 shown in FIG. 1 is an example of the speed monitoring device of the present invention. The numerical control device 2 is an example of a control unit of the present invention. The servo amplifier 7 (servo controller 10) is an example of the servo controller of the present invention. The safety control device 3 is an example of a speed monitoring unit of the present invention. The servo controller 10 that executes the process of the arrow K1 shown in FIG. 2 is an example of the request information transmission means of the present invention. The servo controller 10 that executes the process of the arrow K2 is an example of the position information receiving means of the present invention. The servo controller 10 that executes the process of the arrow K3 is an example of a speed command value transmission unit of the present invention. The position controller 41 of the servo controller 10 that executes the process of assigning the unique ID information of K4 is an example of the identification information assigning means of the present invention. The position controller 41 of the servo controller 10 that executes the process of adding the timer information of K5 is an example of the timer information adding means of the present invention. The position controller 41 of the servo controller 10 that executes the process of assigning the K6 CRC code is an example of the error detection code assigning means of the present invention. The CPU 31 that executes the process of S14 in FIG. 7 is an example of the identification information match determination means of the present invention. The CPU 31 that executes the process of S15 is an example of a timer information coincidence determination unit of the present invention. The CPU 31 that executes the process of S16 is an example of the speed determination means of the present invention. The CPU 31 that executes the process of S17 is an example of the upper limit determination means of the present invention. The CPU 31 that executes the process of S20 is an example of a stop signal output unit of the present invention. The CRC code is an example of the error detection code of the present invention. The STO command output from the CPU 31 of the safety control device 3 to the STO circuit 11 is an example of a stop signal of the present invention.

  The process of the arrow K1 shown in FIG. 2 executed by the servo controller 10 is an example of the request information transmission process of the present invention. The process of the arrow K2 executed by the servo controller 10 is an example of the position information receiving process of the present invention. The process of the arrow K3 executed by the servo controller 10 is an example of a speed command value transmission process of the present invention. The process of providing the unique ID information of K4, which is executed by the position control unit 41 of the servo controller 10, is an example of the identification information adding process of the present invention. The process of S14 in FIG. 7 executed by the CPU 31 is an example of the identification information match determination process of the present invention. The process of S20 executed by the CPU 31 is an example of a stop signal output process of the present invention.

  As described above, the servo system 1 of the present embodiment includes the numerical control device 2, the plurality of motor mechanism units U <b> 1 to Un, and the safety control device 3. The motor mechanism unit U1 includes a motor 5, an encoder 6, and a servo amplifier 7. The numerical controller 2 outputs a control command for driving and controlling the motor 5. The encoder 6 is provided corresponding to the motor 5 and feeds back and outputs the position information of the motor 5. The servo controller 10 of the servo amplifier 7 is provided corresponding to the motor 5 and is connected to the numerical controller 2 and the encoder 6 so as to communicate with each other. The servo controller 10 generates a speed command for the motor 5 using the control command (movement command) from the numerical controller 2 and the position information from the encoder 6 so that the operation of the motor 5 follows the speed command. The motor 5 is driven. The safety control device 3 is communicably connected to each servo controller 10 of the plurality of motor mechanism units U to Un. The safety control device 3 acquires the speed command generated by the servo controller 10 and intercepts communication between the servo controller 10 and the encoder 6 to acquire the position information of the motor 5. Since the position information is position information from the encoder 6 per unit time, it is the current speed. Therefore, the safety control device 3 compares and monitors the acquired speed command and the current speed.

  The servo controller 10 transmits a request information packet requesting the position information of the motor 5 to the encoder 6. The servo controller 10 receives the position information packet returned from the encoder 6 in response to the request information. The servo controller 10 transmits a speed command generated based on the control command and the position information from the numerical control device 2 to the safety control device 3. The servo controller 10 adds unique ID information that can identify the servo amplifier 7 to the request information packet transmitted to the encoder 6 and the speed command packet transmitted to the safety control device 3.

  When the encoder 6 receives the request information packet transmitted from the servo controller 10, the encoder 6 adds the unique ID information added to the request information to the position information packet that is a response to the received request information. Is returned to the servo controller 10.

  The safety control device 3 includes the unique ID information given to the speed command packet received from the servo controller 10 and the unique ID information given to the position information packet obtained by intercepting the communication between the servo controller 10 and the encoder 6. Is determined to match. If it is determined that there is a mismatch, the safety control device 3 outputs an STO command for stopping the driving of the motor 5 to the STO circuit 11. Therefore, the servo system 1 can stop the machine tool in an emergency, and can prevent malfunction. Since the servo system 1 can detect the abnormality of the communication partner by verifying the unique ID information, the speed of the plurality of motors 5 can be monitored by one safety control device 3. Therefore, the servo system 1 does not need to prepare as many safety control devices as the number of the motor mechanism units U1 to Un, so that the cost for the system can be reduced.

  The servo controller 10 of the above embodiment assigns timer information capable of specifying the communication time to the request information packet and the speed command packet to which the unique ID information is assigned, respectively. The encoder 6 receives the request information transmitted by the servo controller 10 and adds the unique ID information and timer information added to the request information to the position information packet that is a response to the received request information. Is returned to the servo controller 10. The safety control device 3 includes timer information given to the speed command packet received from the servo controller 10, timer information given to the position information packet obtained by intercepting communication between the servo controller 10 and the encoder 6, and It is judged whether or not. When it is determined that there is a mismatch, the safety control device 3 outputs an STO command for stopping the operation to the STO circuit 11. Therefore, the servo system 1 can detect a temporal mismatch between the speed command packet and the position information packet. If they do not match, an STO command is output, so that the servo system 1 can more reliably prevent a malfunction caused by a communication abnormality.

  The servo system 1 of the above embodiment includes a communication system that assigns a CRC code to a packet every time the numerical controller 2, the servo controller 10, and the safety controller 3 communicate packets with each other. The servo controller 10 gives a CRC signal to the request information packet and the speed command packet given by the unique ID information and the timer information. When the encoder 6 receives the request information packet transmitted from the servo controller 10, the encoder 6 adds the unique ID information, timer information, and CRC code added to the request information to the position information that is a response to the received request information. The attached position information packet is returned to the servo controller 10. The safety control device 3 includes a CRC code added to the speed command packet received from the servo controller 10, and a CRC code added to the position information packet acquired by intercepting communication between the servo controller 10 and the encoder 6. It is judged whether or not. If it is determined that there is a mismatch, the safety control device 3 outputs an STO command for stopping the operation to the STO circuit 11. Therefore, the servo system 1 can detect an abnormality on the communication path and can prevent malfunction.

  Needless to say, the present invention is not limited to the above-described embodiment, and various modifications are possible. The servo system 1 of the present embodiment is a system for driving a machine tool, but may be a machine device other than a machine tool as long as it is a machine device driven by a plurality of servo motors.

  The servo controller 10 according to the present embodiment transmits a speed command packet to the safety control device 3 using a communication path with the numerical control device 2. However, the servo controller 10 directly transmits the speed command packet to the safety control device 3. Also good. For example, each servo controller 10 of the servo system 100 shown in FIG. 8 is electrically connected directly to the safety control device 3 (see the thick dotted line in FIG. 8), so that it can communicate directly with the safety control device 3. It has become. Since each servo controller 10 of the plurality of motor mechanism units U1 to Un can directly communicate with the safety control device 3, packets can be transmitted and received quickly. Further, since the speed command packet does not pass through the communication path of the numerical control device 2, it is possible to reduce the possibility that the packet data is altered due to, for example, a bug in the application layer that controls the communication of the numerical control device 2.

  In this embodiment, the speed command value in the servo controller 10 is compared with the speed information converted from the position information from the encoder 6. The speed is the amount of change in position per unit time. If the communication cycle for extracting the position information and the control cycle of the servo controller 10 are specified, the movement command received from the numerical controller 2 by the servo controller 10 is output to the safety controller 3. The position information from the encoder 6 may be compared.

  The process of detecting the opening / closing of the door (S12) in the check process (see FIG. 7) of the above embodiment may be omitted. Further, the verification order of the CRC code (S13), the unique ID information (S14), and the timer information (S15) may be other than this. Also, verification of CRC code and verification of timer information may be omitted.

  The error display (S19) of S19 of the check process of the above embodiment may be displayed so that the item in which the error is detected can be seen in each verification process (S12 to S17), for example. An alarm sound may be output together with the display. Further, the error display process may be omitted.

  In the check process (see FIG. 7) of the above embodiment, when the CPU 31 determines that the unique ID information does not match even once in the verification process of S14 (S14: NO), the CPU 31 outputs an STO command that cannot be operated ( In step S20, the arbitrary motor 5 determined to be stopped is stopped. For example, when it is determined that the unique ID information does not match for a certain period of time, an STO command indicating that the operation is disabled may be output.

  The first modification of the check process shown in FIG. 9 adds the determination process of S30 after the determination process of S14: NO to the check process shown in FIG. For example, when the CPU 31 determines that the unique ID information of the speed command packet, the request information packet, and the position information packet does not match (S14: NO), the CPU 31 determines whether or not they match for a predetermined time (S30). ). The certain time may be a time necessary for determining the mismatch of the unique ID information, for example. What is necessary is just to measure the time when unique ID information does not correspond, for example using a timer not shown. If the unique ID information does not match the predetermined time (S30: NO), there is a possibility that the unique ID information is erroneously detected. Therefore, the CPU 31 does not output the STO command for stopping the operation. Proceed to processing.

  If the unique ID information does not match for a certain time (S30: YES), the possibility of erroneous detection of the unique ID information is low, and the possibility that the communication partner is wrong is high. Therefore, the CPU 31 displays an error (S19) and outputs an STO command for stopping the operation (S20). Therefore, since the CPU 31 can stop the motor 5 only when the communication partner is surely wrong, the identification accuracy of the communication partner can be improved. The CPU 31 that executes the process of S30 in FIG. 9 is an example of a time determination unit of the present invention. Note that, in the first modified example, in the other verification processes (S12, S13, S15 to S17), similarly to the process of S30, when an abnormality is detected continuously for a predetermined time or longer, an STO command that cannot be operated is output. May be.

  In the check process of the above embodiment (see FIG. 7), when the CPU 31 detects a mismatch even once in the verification process of S14, the CPU 31 outputs an STO command indicating that the operation is impossible (S20) and determines that the stop is necessary. Although the arbitrary motor 5 is stopped, for example, when an abnormality is detected continuously for a predetermined number of times or more, an STO command that cannot be operated may be output.

  The second modification of the check process illustrated in FIG. 10 adds the process of S40 to the check process illustrated in FIG. 7 after the determination process of S14: NO. For example, if the CPU 31 determines that the unique ID information of the speed command packet, the request information packet, and the position information packet does not match (S14: NO), the CPU 31 determines whether or not the number of consecutive IDs does not match the specified number of times. (S40). For example, the specified number of times may be set to the number of times necessary to determine the unique ID information mismatch. What is necessary is just to count the frequency | count of the continuous mismatch of unique ID information, for example using a counter not shown. If the number of times that the unique ID information is continuously determined to be inconsistent is less than the specified number (S40: NO), there is a possibility that the unique ID information may be erroneously detected. Therefore, the CPU 31 does not output the operation stop STO command. The process proceeds to S15.

  When the number of times of discriminating consecutive mismatches is equal to or greater than the specified number (S40: YES), the possibility of erroneous detection of the unique ID information is low and the possibility that the communication partner is wrong is high. Therefore, the CPU 31 displays an error (S19) and outputs an STO command for stopping the operation (S20). Therefore, as in the first modification, the CPU 31 can stop the motor 5 only when the communication partner is surely wrong, so that the identification accuracy of the communication partner can be improved. The CPU 31 that executes the process of S40 in FIG. 10 is an example of the number determination means of the present invention. In the second modification, in the other verification processes (S12, S13, S15 to S17), as in the case of the process of S40, when an abnormality is detected continuously for a predetermined number of times or more, an STO command that cannot be operated is output. May be.

  In the check process of the above embodiment, the CPU 31 outputs an STO command indicating that operation is not possible and stops any motor 5 that is determined to be stopped if an abnormality is detected in each verification process (S12 to S17). However, all the motors 5 may be stopped.

DESCRIPTION OF SYMBOLS 1 Servo system 2 Numerical control device 3 Safety control device 5 Motor 6 Encoder 7 Servo amplifier 10 Servo controller 31 CPU
41 Position Control Unit 100 Servo System U1 to Un Motor Mechanism Unit

Claims (8)

A control unit that outputs a command signal for driving and controlling each of the plurality of servo motors;
A plurality of encoders that are provided corresponding to each of the plurality of servo motors and that feed back and output position information of the servo motors;
Provided corresponding to each of the plurality of servo motors, connected to the control unit and the encoder so as to communicate with each other, and using the command signal from the control unit and the position information from the encoder A plurality of servo control units for generating a speed command value of the servo motor and driving the servo motor so that the operation of the servo motor follows the speed command value;
Each of the servo control units is communicably connected, acquires the speed command value generated by the servo control unit for each servo motor, intercepts communication between the servo control unit and the encoder, and In a speed monitoring apparatus comprising a speed monitoring unit that acquires information and compares and monitors the acquired speed command value and the position information.
Each of the plurality of servo controllers is
Request information transmitting means for transmitting request information for requesting the position information of the servo motor to the encoder;
Position information receiving means for receiving the position information returned by the encoder in response to the request information transmitted by the request information transmitting means;
Speed command value transmitting means for transmitting the speed command value generated based on the command signal and the position information received by the position information receiving means to the speed monitoring unit;
Identification information that can identify the servo control unit includes identification information providing means for assigning the request information and the speed command value, respectively.
Each of the plurality of encoders is
When the request information transmitted by the request information transmitting means is received, the position information, which is the response to the received request information, is added with the identification information given to the request information. Reply to the servo controller,
The speed monitoring unit
The identification information given to the speed command value received from the speed command value transmitting means coincides with the identification information given to the position information obtained by intercepting communication between the servo control unit and the encoder. Identification information matching judgment means for judging whether or not,
And a stop signal output means for outputting a stop signal for stopping the drive of the servo motor to the servo controller when the identification information match determination means determines that the identification information does not match. Monitoring device. Each of the plurality of servo controllers is
Timer information giving means for giving timer information capable of specifying a communication time to the request information to which the identification information is given and the speed command value, respectively.
Each of the plurality of encoders is
The request information transmitted by the request information transmitting means is received, and the position information, which is the response to the received request information, is added with the identification information given to the request information and the position information given the timer information. , Reply to the servo controller,
The speed monitoring unit
Whether the timer information given to the speed command value received from the servo control unit matches the timer information given to the position information acquired by intercepting communication between the servo control unit and the encoder Timer information matching judgment means for judging whether or not,
The stop signal output means further includes
The speed monitoring apparatus according to claim 1, wherein the stop information is output to the servo control unit when the timer information coincidence judging unit judges that the timer information does not coincide. In the control unit, the servo control unit, and the speed monitoring unit, each time a packet is communicated with each other, a communication system that adds an error detection code to the packet is provided.
Each of the plurality of servo controllers is
An error detection code giving means for giving an error detection code to the request information and the speed command value given by the identification information and the timer information;
Each of the plurality of encoders is
When the request information transmitted by the request information transmitting means is received, the position information that is a response to the received request information, the identification information given to the request information, the timer information, and the error detection The position information given the code is returned to the servo control unit,
The speed monitoring unit
The error detection code given to the speed command value received from the speed command value transmission means, and the error detection code given to the position information acquired by intercepting communication between the servo control unit and the encoder. An error detection code match determination means for determining whether or not they match,
The stop signal output means further includes
3. The speed monitoring apparatus according to claim 2, wherein the stop signal is output to the servo control unit when the error detection code match determination unit determines that the error detection code does not match. 4. The speed monitoring unit
The speed command value received from the speed command value transmitting means is compared with a current speed value obtained by converting the position information acquired by intercepting communication between the servo control unit and the encoder into a speed value, and is determined in advance. It has a speed judgment means for judging whether or not a mismatch has occurred beyond the allowable value,
The stop signal output means further includes
4. The stop signal is output to the servo control unit when the speed determination unit determines that a mismatch has occurred exceeding the allowable value. Speed monitoring device. The speed monitoring unit
Both the speed command value received from the speed command value transmitting means and the current speed value obtained by converting the position information acquired by intercepting communication between the servo control unit and the encoder to a speed value are predetermined. An upper limit determination means for determining whether or not the upper limit value is less than or equal to
The stop signal output means further includes
The upper limit value determining means outputs the stop signal to the servo control unit when it is determined that at least one of the speed command value and the current speed exceeds the predetermined upper limit value. The speed monitoring apparatus according to any one of claims 1 to 4. The speed monitoring unit
A time determination means for determining whether or not the state in which the identification information match determination means has determined that the identification information does not match continues for a certain time or more;
The stop signal output means further includes
The stop signal is output to the servo control unit when the time determination unit determines that the state in which the identification information is inconsistent is continued for the predetermined time or more. The speed monitoring apparatus according to any one of 1 to 5. The speed monitoring unit
A number of times determination means for determining whether or not the determination that the identification information matches by the identification information match determination means has continued for a predetermined number of times,
The stop signal output means further includes
6. The stop signal is output to the servo control unit when the number determination unit determines that the determination that the identification information is inconsistent has continued for a predetermined number of times or more. The speed monitoring device according to any one of the above. A control unit that outputs a command signal for driving and controlling each of the plurality of servo motors;
A plurality of encoders that are provided corresponding to each of the plurality of servo motors and that feed back and output position information of the servo motors;
Provided corresponding to each of the plurality of servo motors, connected to the control unit and the encoder so as to communicate with each other, and using the command signal from the control unit and the position information from the encoder A plurality of servo control units for generating a speed command value of the servo motor and driving the servo motor so that the operation of the servo motor follows the speed command value;
Each of the servo control units is communicably connected, acquires the speed command value generated by the servo control unit for each servo motor, intercepts communication between the servo control unit and the encoder, and In a speed monitoring method of a speed monitoring device that includes information, and a speed monitoring unit that monitors and compares the acquired speed command value and the position information,
Each of the plurality of servo controllers is
A request information transmission step for transmitting request information for requesting the position information of the servo motor to the encoder;
A position information receiving step of receiving the position information returned by the encoder in response to the request information transmitted in the request information transmitting step;
A speed command value transmitting step of transmitting the speed command value generated based on the command signal and the position information received in the position information receiving step to the speed monitoring unit;
Identification information that can identify the servo control unit, and an identification information provision step for assigning the request information and the speed command value, respectively, each of the plurality of encoders,
When the request information transmitted in the request information transmission step is received, the position information to which the identification information given to the request information is added to the position information that is a response to the received request information, Reply to the servo controller,
The speed monitoring unit
The speed command value transmitted in the speed command value transmission step is received, the identification information given to the received speed command value, and the position information acquired by intercepting communication between the servo control unit and the encoder An identification information matching determination step for determining whether or not the identification information given to
And a stop signal output step of outputting a stop signal for stopping the drive of the servo motor to the servo controller when the identification information is determined to be inconsistent in the identification information match determination step. Method.